![Introduction 3
networks with mobile client devices communicating with each other directly
or through other nodes in multi-hop configuration (Fig. 1.1a). Here client
nodes may function as routing nodes for others that are not within each other’s
communication range. In immobile wireless mesh network, the access radio
nodes and gateway nodes are stationary, and the client devices connect to the
access node (Fig. 1.1b). MANET organization may vary in time—nodes are
being connected and disconnected, they replace their point of connection
(their neighborhood evolves), and dynamically adapt themselves to the topol-
ogy changes. As a matter of fact, nothing is fixed; in contrast to classical net-
working,a MANET node may disappear at anytime,causing serious disruptions
to the neighboring nodes. Furthermore, routing of the information must be
planned in a dynamic manner so as to be able to deal with the evolving
network topology (the route for the outgoing packet and the incoming packet
between a pair of nodes may be different, as the topology may change even
during the period of a single transmission).
When we speak about MANETs, we think about mesh networking. A
wireless* mesh network can be in general configured as a hierarchical network
made up of home area network (HAN), Neighborhood Area Network (NAN),
and wide area network (WAN), each utilizing the most suitable wireless tech-
nologies for their needs. For HAN, IEEE 802.11- and IEEE 802.15.4-based
ZigBee (ZigBee Alliance, 2012) are thought of as most suitable. In the major-
ity of cases, a single access point (AP) or ZigBee host is sufficient in the home
scenario. If the source and destination nodes do not reside within the same
NAN, the traffic from the various HANs is routed to one or more gateway
nodes that backhaul the traffic utilizing high speed mobile data technologies,
such as 3G,HSPA/HSPA+,LTE,LTE-A,orWiMax (3GPP Specifications,2012;
IEEE Wireless MAN [WiMax], 2012; WiMax Forum, 2012). The preferred
solution to cover a wide area (resulting in a NAN), such as a neighborhood,
a campus, or a city is to use IEEE 802.11x WLAN (aka WiFi) in mesh configu-
ration. Figure 1.2 shows a generic wireless mesh network depicting the various
scenarios. Figure 1.3 shows the use of lower frequency white spaces between
the TV channels (which is at much lower frequencies than 2.4 GHz) in the
ultra-high frequency (UHF) band (470–890 MHz) to create longer distance
Internet connections that easily penetrate through the physical obstructions.
These are still unlicensed and therefore their use is free and similar to WiFi
and Bluetooth. This type of networking technology is called “Super WiFi” by
the Federal Communications Commission (FCC) (Regulators, 2012; Segan,
2012). It should be noted that there is no similarity with the WiFi technology,
and the use of “Super WiFi” is confusing and controversial with the Wi-Fi
Alliance (WiFi, 2012; US regulators, 2012).
Traditionally, wireless network design is based on the centralized architec-
ture where the base stations control the operation of the wireless services
* To simplify the description, we consider wireless connections only.](https://image.slidesharecdn.com/2157029-250609175410-7552bc00/85/Wifi-Wimax-And-Lte-Multihop-Mesh-Networks-Basic-Communication-Protocols-And-Application-Areas-Hungyu-Wei-29-320.jpg)
![Anonymity versus Authorization and Authentication 13
nontrusted access devices of other users as intermediate nodes. Now, if we use
VPN-equivalent techniques, why should an intermediate node trust that the
network traffic is not going to violate common rules? And, vice-versa, if non-
encrypted information is sent to intermediate nodes to convince them that the
source node is obeying the rules, who will guarantee that the intermediate
nodes will not change or block the information? Moreover, how do we balance
a natural behavior of blocking others’ traffic, for example, to conserve the
battery power or to save on the bandwidth resources? A discussion on these
topics will be provided in the remainder of this chapter.
Let us next discuss the question: how many hops are sufficient or necessary?
The simplest case is that of one access point and two-hop networking—
everybody connects to such an access point in the ad-hoc manner, but the
access point itself is connected to the fixed network.There are several reasons
for such nondirect network utilization—some of them are purely technical
(limited signal, no required communication module, etc.), while some of them
are financial (high costs of direct networking, e.g., HSPA [high speed packet
access] [HSPA, 2012], when compared with ad-hoc networking, providing free
access).Another reason is practicality when most of our traffic is local and we
connect to the wide network at random,for example,to synchronize our e-mail
boxes. For example, all the passengers of a city bus may enjoy Internet con-
nection, performing ad-hoc communication with an onboard device that in
turn multiplexes the traffic to an outcoming WiMAX channel. Of course, the
passengers may communicate locally as well among themselves through their
access devices. A similar use case can be found with the passengers on an
airplane where the Internet connection is made via a satellite link.
If we consider short-range networking, it is soon discovered, however, that
the two-hop technique is not sufficient in many cases, and we have to extend
the networking range by using other devices as intermediate relays. However,
as already discussed, from the technical point of view, it is not advisable to
apply more than three to four hops for a single transmission, as the overhead
involved to compute the route and to find the return path to send a response
back is extremely huge. In addition, the field tests have shown that on average,
the throughput drops by about one-half with every additional hop. Therefore,
in this chapter, we limit our discussion to only two or three hops to access a
wide-area network gateway node, while reserving the discussion on more than
three hops to special scenarios, such as propagation of a security alert, and first
responders in natural emergency cases.
2.3. ANONYMITY VERSUS AUTHORIZATION
AND AUTHENTICATION
As previously discussed, ad-hoc activities are usually related with the anonym-
ity. Going back to the example of connecting with a random person for finding
directions, it would be a bad idea to start such an activity by asking the person](https://image.slidesharecdn.com/2157029-250609175410-7552bc00/85/Wifi-Wimax-And-Lte-Multihop-Mesh-Networks-Basic-Communication-Protocols-And-Application-Areas-Hungyu-Wei-39-320.jpg)
![Addressability 25
and globally used? The answer to the first question is “definitely not,” and
for the latter “not necessarily.” Therefore, the approaches to addressing in
classical networks are not directly applicable to multi-hop and ad-hoc
networks. However, there are heuristic solutions that are possible. First, we
may have to give up the idea of ad-hoc identification of any node, and
require that communication will be allowed only with well-addressable,
nonanonymous nodes. Here, one interlocutor, that is, a destination of a
communication link, is stable and well known, while the initiator at the other
end of the link may remain anonymous, except for low-level technical
information needed for return routing. This would be the case for public
service providers, such as restaurants, taxis, hotels, shops. Second, those who
want to be addressable may register their identifiers (usually pseudonyms or
even neural technical numbers, such as device MAC address or International
Mobile Equipment Identity [IMEI] [IMEI, 2010] number) somewhere in
the network in a public, centralized database. These identifiers must be
accompanied with some parameters useful for contextual selection of the
device among other devices. For example, these parameters may describe
some skills and capabilities of the device owner (e.g., “I am able to play
chess.”), and some dynamic values, such as the current geoposition of the
device. Third, we may assume that every anonymous message, that is, a
request for “anyone,” is broadcasted to everyone in the local neighborhood
(to any device capable of receiving such message). We assume that at any
time, the number of devices within the range is reasonably small. Usually, the
communication is one-way as the initiator does not expect that many users
would respond. This could also mean resending the message to devices
beyond the immediate neighborhood in a multi-hop mode. Some real-life
applications of such systems fall within the domain of public security (e.g.,
traffic alert system—“traffic jam behind” and “danger, escape quickly”).
In the first and the third examples earlier, the receiver is (somehow) well-
known and thus fully addressable to the sender. However, that is not the case
in the second example.To select a single device from a set of possible devices-
in-range, we may use only the set of description parameters stored in the
database. So, we have to provide a binding mechanism using a mapping pro-
cedure for a set of parameter values to an identifier (a pseudonym) of a single
device, which is “the best.” There are at least two problems in such a binding
approach. First, the set of actual parameter values may be incomplete, that is,
not all the parameters may be updated with current and correct values. For
example, we do not necessarily know the real name of the device owner.
Second, some descriptor values could be fuzzy and incomplete. For example,
we may want to address a device “in the neighborhood,” but the neighborhood
is not defined in terms of the exact distance in meters! Some of these fuzzy
searching problems have been already discussed in the area of geographic
systems and databases, as well navigation-support systems and personal
devices. However, not all choices can be quantified for all situations and for
everyone.](https://image.slidesharecdn.com/2157029-250609175410-7552bc00/85/Wifi-Wimax-And-Lte-Multihop-Mesh-Networks-Basic-Communication-Protocols-And-Application-Areas-Hungyu-Wei-51-320.jpg)
![Addressability 27
• A user (with certain privileges) may request the database for either:
s a detailed description of the current state of a device, on condition that
the unique identifier of this device is given as an input parameter, or
s a set of identifiers of the devices fulfilling certain criteria, to be verified
by means of the current values of the description parameters.
As for the first case, this is similar to the classical addressing mechanism, and
may be used for classical searching and accessing the well-known fixed network
nodes (cf. the previously presented application area with fixed services, such
as restaurants, ATM [automated teller machine]* locations, etc.).
The second case is much more interesting, but much more complex. Even
if some parameter values are quite stable (such as the name of a device owner,
a color and license plate number of his/her car, real address, etc.), there are
also some values that may vary (such as the geoposition of the access device).
Thus, classical addressing cannot be applied. Instead, we need a declarative
query language rather than fixed DNS addresses. A computed result of such
a query would have the same meaning as a DNS/IP address, or a set of
addresses for a multicast communication.
We propose the approach of eDNS query language,† which is a loose adap-
tation of the well-known SQL query language (SQL, 2012). We provide more
details of the eDNS in the following:
select driver from my_current_position + 1 mile where
licence plate like NY123*;
select license_plate from highway_51 where speed>55mph;
Note that the proposed query language must use a fixed set of parameters (not
necessarily domain names), which is similar to the original SQL language that
uses existing relational database. Thus, in order to compute the queries, one
must include in the description such parameters as current geoposition (both
of the query sender and all the other cars involved), current speed, license
plate numbers of the cars, highway identifiers, and so on.
Going further, we may propose a fuzzy query language, enabling a descrip-
tion of the destination device in the form of a semi-natural-language text, for
example (taking inspiration from the telematics context):
„To the yellow Ford Transit just passing me by”
„To Ferrari No NY1234”
„To the pretty girl in a funny car just after my car”
† Note that this is not a proposal for a new declarative language—this is rather an indication how
we could improve anonymous and fuzzy addressing in ad-hoc and multi-hop networks.
* A note for EU citizens: we also call these places a “cash machine” or a “dispenser.”](https://image.slidesharecdn.com/2157029-250609175410-7552bc00/85/Wifi-Wimax-And-Lte-Multihop-Mesh-Networks-Basic-Communication-Protocols-And-Application-Areas-Hungyu-Wei-53-320.jpg)
Wifi Wimax And Lte Multihop Mesh Networks Basic Communication Protocols And Application Areas Hungyu Wei
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- 5. WIFI, WIMAX, AND LTE MULTI-HOP MESH NETWORKS
- 6. WILEY SERIES ON INFORMATION AND COMMUNICATION TECHNOLOGY Series Editors: T. Russell Hsing and Vincent K. N. Lau The Information and Communication Technology (ICT) book series focuses on creating use- ful connections between advanced communication theories, practical designs, and end-user applications in various next generation networks and broadband access systems, including fiber, cable, satellite, and wireless. The ICT book series examines the difficulties of applying various advanced communication technologies to practical systems such as WiFi, WiMax, B3G, etc., and considers how technologies are designed in conjunction with stan- dards, theories, and applications. The ICT book series also addresses application-oriented topics such as service manage- ment and creation and end-user devices, as well as the coupling between end devices and infrastructure. T. Russell Hsing, PhD, is the Executive Director of Emerging Technologies and Services Research at Telcordia Technologies. He manages and leads the applied research and devel- opment of information and wireless sensor networking solutions for numerous applications and systems. Email: thsing@telcordia.com Vincent K.N. Lau, PhD, is Associate Professor in the Department of Electrical Engineering at the Hong Kong University of Science and Technology. His current research interest is on delay-sensitive cross-layer optimization with imperfect system state information. Email: eeknlau@ee.ust.hk Wireless Internet and Mobile Computing: Interoperability and Performance Yu-Kwong Ricky Kwok and Vincent K. N. Lau Digital Signal Processing Techniques and Applications in Radar Image Processing Bu-Chin Wang The Fabric of Mobile Services: Software Paradigms and Business Demands Shoshana Loeb, Benjamin Falchuk, and Euthimios Panagos Fundamentals of Wireless Communications Engineering Technologies K. Daniel Wong RF Circuit Design, Second Edition Richard Chi-Hsi Li Networks and Services: Carrier Ethernet, PBT, MPLS-TP, and VPLS Mehmet Toy Equitable Resource Allocation: Models, Algorithms, and Applications Hanan Luss Vehicle Safety Communications: Protocols, Security, and Privacy Luca Delgrossi and Tao Zhang WiFi, WiMAX, and LTE Multi-hop Mesh Networks: Basic Communication Protocols and Application Areas Hung-Yu Wei, Jarogniew Rykowski, and Sudhir Dixit
- 7. WIFI, WIMAX, AND LTE MULTI-HOP MESH NETWORKS Basic Communication Protocols and Application Areas Hung-Yu Wei National Taiwan University, Taiwan Jarogniew Rykowski Poznań University of Economics, Poland Sudhir Dixit Hewlett-Packard Laboratories, India
- 8. Copyright © 2013 by John Wiley & Sons, Inc. All rights reserved Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permissions. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com. Library of Congress Cataloging-in-Publication Data: Wei, Hung-Yu. WiFi, WiMAX, and LTE multi-hop mesh networks : basic communication protocols and application areas / Hung-Yu Wei, Jarogniew Rykowski, Sudhir Dixit. pages cm ISBN 978-0-470-48167-7 (pbk.) 1. Ad-hoc networks (Computer networks) 2. Wireless LANs. I. Title. TK5105.77.W45 2013 004.6'2—dc23 2012040269 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1
- 9. CONTENTS Foreword xi Preface xiii About the Authors xvii List of Figures xix List of Tables xxv 1 Introduction 1 2 Architectural Requirements for Multi-hop and Ad-Hoc Networking 9 2.1. When and Where Do We Need Ad-Hoc Networking? 9 2.2. When Do We Need Multi-hop? How Many Hops Are Sufficient/Necessary? 12 2.3. Anonymity versus Authorization and Authentication 13 2.4. Security and Privacy in Ad-Hoc Networks 17 2.5. Security and Privacy in Multi-hop Networks 18 2.6. Filtering the Traffic in Ad-Hoc Networking and Multi-hop Relaying 20 2.7. QoS 23 2.8. Addressability 24 2.9. Searchability 28 2.10. Ad-Hoc Contexts for Next-Generation Searching 29 2.11. Personalization Aspects in Ad-Hoc Information Access 31 2.12. Multi-hop Networking: Technical Aspects 32 2.13. Summary 34 2.13.1. Do We Really Need Ad-Hoc and Multi-hop Networking? If So, When and Where? 35 2.13.2. When and Where Do We Need Ad-Hoc Networking? 35 2.13.3. How Do We Effectively Combine Anonymity/ Privacy with Safety/Security? 36 2.13.4. How Do We Personalize Network Access, Including User-Oriented Information Filtering? 37 v
- 10. vi Contents 2.13.5. How Do We Access Places/Devices/Information in a Highly Dynamic Environment of an Ad-Hoc and Multi-hop Network Affecting Addressability, Searchability, and Accessibility of Data? 37 2.13.6. How Do We Support Frequently Dis- and Reconnected Users, Including Efficient Propagation of Important Information to Newcomers? 38 2.13.7. How Many Hops Are Allowed/Effective for a Typical Multi-hop Information Exchange? Is Relaying Affected with the Security/Privacy Issues? 38 3 Application Areas for Multi-hop and Ad-Hoc Networking 42 3.1. Telematics 42 3.1.1. Introduction to Telematics Applications 42 3.1.2. Ad-Hoc Enhanced Navigation Support 44 3.1.3. Traffic Lights Assistance 52 3.1.4. CB-Net Application 56 3.1.5. City-Transportation Integrated Support 62 3.2. E-Ticket Applications 67 3.3. Telemedicine 69 3.4. Environment Protection 71 3.5. Public Safety 73 3.5.1. Ad-Hoc Monitoring for Public Safety Applications 74 3.5.2. Broadcasting Public Safety Information 81 3.6. Groupware 84 3.7. Personal, Targeted, Contextual Marketing and Shopping Guidance 85 3.8. Intelligent Building 87 3.8.1. “Intelligent Hospital” Idea 90 3.8.2. “Interactive Museum” Idea 92 3.8.3. Intelligent Ad-Hoc Cooperation at a Workplace 93 3.9. Business Aspects of Multi-hop and Ad-Hoc Networking 94 3.9.1. Monetary Unit for Ad-Hoc and Multi-hop Services 94 3.9.2. Which Ad-Hoc and Multi-hop Functionality Should Be Paid For? 96 3.9.3. Quality-of-Service and Trustability 97 3.9.4. Pay-per-Access Mode and Subscriptions 98 3.9.5. Legal Regulations 100 3.9.6. Ad-Hoc and Multi-hop Networking versus Commercial Networks and Network Providers 100 3.10. Summary 102 4 Mesh Networking Using IEEE 802.11 Wireless Technologies 109 4.1. IEEE 802.11 110 4.1.1. WiFi and IEEE 802.11 Wireless LAN 111 4.1.2. IEEE 802.11 Mesh Network Architectures 113
- 11. Contents vii 4.2. IEEE 802.11s: Standard for WLAN Mesh Networking 116 4.2.1. Additional Functions in 802.11s 120 4.2.2. WiFi Certification and Deployments of IEEE 802.11s 120 4.3. Summary 121 5 Wireless Relay Networking Using IEEE 802.16 WiMAX Technologies 122 5.1. IEEE 802.16 Overview and Architecture 122 5.2. IEEE 802.16j Relay System Overview 123 5.2.1. Nontransparent Relay versus Transparent Relay 124 5.2.2. Connection Types 125 5.2.3. MAC PDU Transmission Mode 126 5.2.4. Relay MAC PDU 128 5.2.5. Subheaders in Relay MAC PDU 131 5.3. IEEE 802.16j Frame Structure 132 5.3.1. Frame Structure in Nontransparent Mode 135 5.3.2. Frame Structure in Transparent Mode 137 5.4. Path Management in 802.16j Relay 139 5.4.1. Explicit Path Management 140 5.4.2. Implicit Path Management 142 5.4.3. Contiguous Integer Block CID Assignment for Implicit Path Management 143 5.4.4. Bit Partition CID Assignment for Implicit Path Management 144 5.4.5. Path Selection and Metrics 146 5.5. Radio Resource Management 147 5.5.1. RRM with Distributed Scheduling 147 5.5.2. Bandwidth Request Mechanism in WiMAX 147 5.5.3. Downlink Flow Control 154 5.5.4. RRM with Centralized Scheduling 156 5.5.5. SS-Initiated Bandwidth Request in Centralized Scheduling 159 5.6. Interference Management 163 5.6.1. Interference Measurement 163 5.6.2. RS Neighborhood Discovery and Measurements 167 5.6.3. Relay Amble (R-Amble) Transmission 168 5.7. Initialization and Network Entry 170 5.7.1. Network Entry Overview 170 5.7.2. Network Entry for Relay Station 172 5.7.3. Fast Reentry 176 5.7.4. Network Entry for Subscriber Station (Through RS) 177 5.8. Mobility Management and Handoff 177 5.8.1. Design Issues: Mobility Management in Multi-hop Relay Network 177
- 12. viii Contents 5.8.2. Overview of Mobile Station Handoff Protocol Design in 802.16j 179 5.8.3. Neighborhood Network Topology Advertisement 180 5.8.4. Mobile Node Scanning 181 5.8.5. Association 183 5.8.6. Handoff Execution 185 5.8.7. Handoff Optimization with Context Transfer 186 5.8.8. Mobile Relay Station Handoff 187 5.9. Power Management 189 5.9.1. Sleep Mode 191 5.9.2. Idle Mode 193 5.10. HARQ and Reliable Transmission 195 5.10.1. Design Issues: HARQ in Multi-hop Relay Network 195 5.10.2. Overview of HARQ Design in 802.16j 196 5.10.3. HARQ in Centralized Scheduling 197 5.10.4. Downlink HARQ in Nontransparent Mode 198 5.10.5. Downlink HARQ in Transparent Mode: Hop-by-Hop HARQ Operation 202 5.10.6. Downlink HARQ in Transparent Mode: RS-assisted HARQ 204 5.10.7. Uplink HARQ in Nontransparent Mode 207 5.10.8. Uplink HARQ in Transparent Mode 209 5.10.9. HARQ in Distributed Scheduling 211 5.11. Multicast, Broadcast, and RS Grouping 211 5.11.1. Multicast and Broadcast 211 5.12. RS Grouping 215 5.13. Summary 220 6 Wireless Relay Networking with Long Term Evolution (LTE) 221 6.1. Overview of the LTE Relay System 221 6.1.1. LTE Relay Deployment Scenario 223 6.1.2. Overview of Resource Partitioning in In-Band Relay 224 6.2. Physical Layer for LTE Relay 226 6.2.1. Physical Layer Channels 226 6.2.2. Frame Structure in Physical Layer Channels 227 6.3. LTE Relay System Architecture 228 6.3.1. Protocol Stacks for Radio Interface 228 6.3.2. S1 Interface 231 6.3.3. RN Initialization and Startup Procedure 234 6.4. LTE Relay System Design Issues 237 6.4.1. Overview of Architecture and Design Issues 237 6.4.2. Design Issue: Downlink Flow Control 238 6.4.3. Design Issue: End-to-End QoS Configuration 238
- 13. Contents ix 6.4.4. Design Issue: Un Interface Configuration 239 6.4.5. Design Issue: Connection Establishment 240 6.4.6. Design Issue: Radio Link Failure and Connection Reestablishment 240 6.4.7. Design Issue: Other Design Options 241 6.5. Future Development in LTE Relay 242 6.5.1. Mobile Relay 242 6.5.2. Advanced Link Transmission 242 6.5.3. Other Deployment Scenarios and Architecture 243 6.6. Summary 244 7 Summary 245 References 247 Index 251
- 14. FOREWORD xi Increasing complexity of communication networks is a growing challenge for network designers, network operators, and network users. This raises the question of how this increased complexity can be reasonably managed without adding even more complexity,while also reducing or completely elimi- nating the cost of network operations and management. Therefore, the self- organizing characteristic of networks, whether in access, metro, core, or end-to-end, is being hailed as the next holy grail of (and a potentially disrup- tive technology in) networking and communication. Imagine wireless nodes (an internet of people, things, devices, and services) being able to connect with each other autonomously and self-organize based on their battery power, bandwidth needs,security requirements,and billing costs,among other require- ments, with or without an entity in control. Indeed, it is going to change the game by opening up lots of new possibilities both technologically and com- mercially. Wireless mesh networking (WMN) technology enables the wireless entities to connect autonomously and reconfigure in the face of changing radio environment. WMN is rapidly evolving and reaching the mainstream, made possible by several standards that have been developed, and vendors and service providers building to those standards. WMNs can range from mobile ad-hoc networks (MANETS) to infrastructure-based stationary networks and can even be multi-hop. The three predominant mesh technologies that have been standardized and deployed are IEEE WLAN (aka Wi-Fi), WiMAX, and LTE.From the commercial perspective,WMNs enable various business models, ranging from free to billable, depending on whether or not a service provider is involved. This book provides an excellent overview of wireless mesh networks in a manner that is easy for a nonexpert to understand, yet technical to the extent that the reader can appreciate the why, what, and how of mesh networking and the strengths and weaknesses of the dominant mesh networking standards: Wi-Fi, WiMAX, and LTE. What is unique about this book is that the authors take a very logical top-down approach. They first spend a good deal of time defining/explaining the topic, such as describing the compelling application areas driving the need for mesh networking, then they describe the various technical challenges emanating from those potential use cases, followed by a detailed technical overview of the various types of wireless mesh networks, their evolution to support IEEE WLAN to 4G technologies of WiMAX and LTE and beyond 4G (such as the LTE-Advanced). Since understanding the
- 15. xii FOREWORD technologies alone is not sufficient to develop a complete system, the authors also discuss the architectural and deployment issues of WMNs in great detail. This is the first book of its kind that has been written in a style best suited to those who wish to get a broad overview of WMNs, while avoiding the math- ematics, formulas, and deep technical details. I am glad to find that the authors have not hesitated to bring out the technical and business challenges that WMNs face, which open up new vistas to research. I have enjoyed reading the manuscript, and I am sure you will enjoy the book, too! Prith Banerjee Executive Vice President and Chief Technology Officer, ABB Ltd Formerly Senior Vice President of Research and Director, Hewlett-Packard Laboratories
- 16. PREFACE xiii Notwithstanding its infancy, wireless mesh networking (WMN) is a hot and growing field. Wireless mesh networks began in the military, but have since become of great interest for commercial use in the last decade, both in local area networks and metropolitan area networks. The attractiveness of mesh networks comes from their ability to interconnect either mobile or fixed devices with radio interfaces, to share information dynamically, or simply to extend range through multi-hopping. This enables easy use and reliability through alternate connectivity paths between source and destination nodes. Mesh networks are of immense interest throughout the world, and there is no reason to believe that this trend will diminish, as we live in a world where wireless continues to increase in popularity in all kinds of devices and access networks. This is primarily due to the need for devices to connect wirelessly in the immediate neighborhood and users wanting connectivity from any- where anytime, whether mobile or stationary. Furthermore, the vision of a hyperconnected world will certainly strengthen the importance of wireless mesh networks in the future. The trends in location- and context-based social networking, wireless content and service delivery, sensor networks, vehicle area networks, and enterprises going wireless and mobile will only boost the role of mesh networks in the future. In the early days of WMNs, there were indeed exaggerated claims about their capabilities and applicabilities to all types of scenarios, which are natural of any new technology going through the hype cycle; but recently, such networks are finding true applications when they are carefully designed and deployed for specific scenarios and use cases. While the consumers, solution developers, and networking engineers are typically not interested in the intricate details of technology, they are certainly interested in issues they might end up dealing with and the solutions to those issues. Nonetheless, in networking today, some knowledge of technology is essential to arriving at the correct networking architecture and choosing the correct equipment and software; otherwise, the goal of attaining the desired performance may remain unfulfilled. In this book, we provide broad coverage of wireless mesh networks in a manner that is easy to understand, yet techni- cal. The book is intended for those who wish to learn about mesh networking from a practical point of view,but feel intimidated by the deep technical details found in the standards documents and/or textbooks.We explain the motivation behind WMNs, their evolution from IEEE WLAN to WiMAX to long term evolution (LTE) and to LTE-Advanced, and what lies ahead in the future.
- 17. xiv PREFACE Throughout the book, we have kept the use of mathematics and formulas to a minimum, and wherever we have had to use them we have made sure that the equations are explained qualitatively and the flow of the material remains seamless.Wherever and whenever appropriate, we have given ample examples of user scenarios, deployable architectures, and real-world implementations using commercially available equipment. It is impossible to cover in detail a broad topic such as WMN in a single book. Therefore, rather than cover every topic in detail, we have presented the key concepts, architectures, and dominant wireless technologies, as well as discussed the performance issues in general and some of the real-world imple- mentations in more specific terms.The book is organized in seven independent parts to allow the reader to skip the parts with which he or she may already be familiar (Fig. P.1). The first chapter introduces the reader to the subject of mesh networking and describes the drivers behind this important technology. Figure P.1. Organization of the book. WiFi, WiMAX, and LTE Multi-hop Mesh Networks Introduction Architectural Requirements for Multi-hop and Ad-Hoc Networking Application Areas for Multi-hop and Ad-Hoc Networking Mesh Networking Using IEEE 802.11 Wireless Technologies Wireless Relay Networking Using IEEE 802.16 WiMAX Technologies Wireless Relay Networking with Long Term Evolution (LTE) Summary
- 18. PREFACE xv The second and third chapters address the architectural and business/econom- ics aspects of mesh networking. These chapters also cover some key applica- tion areas of mesh networking. Chapter 4 briefly describes the application of mesh concepts to IEEE 802.11 (WiFi) Wireless LAN, where it all began and is probably the most researched and written about. Chapter 5 covers the topic of mesh networking in IEEE 802.16 (WiMAX) radio access networks. Chapter 6 presents mesh and relay networking in LTE and LTE-Advanced radio access networks standardized by the International Telecommunication Union. Both IEEE 802.16 and LTE/LTE-A wireless standards have been defined and posi- tioned as 4G radio technologies. Finally, in Chapter 7, we summarize the book and discuss the future directions in wireless mesh networks. We thank Dr. Russell Hsing of Telcordia, ICT Book Series Editor, John Wiley and Sons, and Dr. Simone Taylor of John Wiley and Sons for their patience with us (with several missed deadlines) while we worked on the manuscript. Finally, we have made every attempt to be accurate and factual in the book, but it would be surprising if there were no errors, which would be solely ours. Please send any questions, comments, or corrections directly to us. Hung-Yu Wei Taiwan hywei@cc.ee.ntu.edu.tw Jarogniew Rykowski Poznań, Poland rykowski@kti.ue.poznan.pl Sudhir Dixit Palo Alto, CA, USA sudhir.dixit@ieee.org January 31, 2013
- 19. ABOUT THE AUTHORS xvii HUNG-YU WEI received a BS degree in Electrical Engineering from National Taiwan University in 1999. He received MS and PhD degrees in Electrical Engineering from Columbia University in 2001 and 2005, respectively. Dr.Wei was a summer intern at Telcordia Applied Research in 2000 and 2001. He was with NEC Labs America from 2003 to 2005. He joined the Department of Electrical Engineering at the National Taiwan University in July 2005 as an Assis- tant Professor, and he is currently Associate Professor in the Department of Electrical Engineering and Graduate Institute of Communication Engineering at National Taiwan University. He received the NTU Excellent Teaching Award in 2008 and the “Recruiting Outstanding Young Scholar Award” from the Foundation for the Advancement of Outstanding Scholarship in 2006. He was a consulting member of the Acts and Regulation Committee of the National Communica- tions Commission during 2008∼2009.He has been participating in IEEE 802.16 and 3GPP standardization activities. His research interests include wireless networking, game theoretic models for communications networks, and mobile computing. JAROGNIEW RYKOWSKI received an MSc degree in Computer Science from the Technical University of Poznań, Poland in 1986 and a PhD degree in Computer Science from the Technical University of Gdansk, Poland in 1995. In 2008, he received a habilitation degree from the Institute of Computer Science, Polish Academy of Science (Warsaw, Poland). From 1986 to 1992, he was with the Institute of Computing Science at theTechnical University of Poznań.From 1992 to 1995, he worked as an Assistant in the Franco-Polish School of New Information and Communication Technologies in Poznań. In 1995, he became an Associate Professor in the School. Since 1996, he has been with the Poznań University of Economics, working as an Assistant Professor in the Department
- 20. xviii ABOUT THE AUTHORS of Information Technology. He participated in several industrial projects concerning operating systems, networks, programming language compilers (assemblers and LISP), multimedia databases, and distributed systems for e-commerce. His research inter- ests include software agents, with special emphasis put on personalized access to WWW servers by means of mobile devices and telecommunication networks.His recent interests have gone toward applications of Internet of Things and calm-computing devices, including “intelligent buildings and workplaces,” semantic support for IoT systems, telematics, ad-hoc and multi-hop networking, and related systems. He is the author and coauthor of 3 books, over 45 papers in journals and conference proceedings, and 2 patents. SUDHIR DIXIT is the Director of Hewlett- Packard Laboratories, India. Prior to joining HP Labs in June 2009 in Palo Alto, Califor- nia, Dr. Dixit held a joint appointment as CTO at the Centre for Internet Excellence and Research Manager at the Centre for Wireless Communications, both at the Uni- versity of Oulu, Finland. From 1996 to 2008, he held various positions with Nokia: Senior Re search Manager, Research Fellow, Head of Nokia Research Center (Boston), and in the later years, as Head of Network Technol- ogy (USA) for Nokia Siemens Networks. He has also held the position of Senior Director at Research In Motion, and other senior management and technical positions at such companies as Verizon (previously NYNEX and GTE Labs), Motorola, Wang Labs, and Harris Corporation. Dr. Dixit received his PhD degree in Electronic Science and Telecommunications from the University of Strathclyde, Glasgow, UK, MBA degree from the Florida Institute of Technology, Melbourne, Florida, ME degree from the Birla Institute ofTechnology and Science,Pilani,India,and BE degree from Maulana Azad National Institute of Technology, Bhopal, India. He is an Adjunct Profes- sor of Computer Science at the University of California, Davis, and a Docent (Adjunct Professor) of Telecommunications at the University of Oulu. He has published over 200 papers, edited 5 books, and holds 20 patents. He is a Fellow of IEEE (USA), IET (UK), and IETE (India).
- 21. LIST OF FIGURES Figure P.1. Organization of the book. xiv Figure 1.1. Examples of (a) mobile ad-hoc (infrastructureless) mesh network and (b) immobile (infrastructure-based) mesh network. 2 Figure 1.2. Use of long range WLAN (Super WiFi) mesh to extend coverage to larger areas. 4 Figure 1.3. Use of long range WLAN (Super WiFi) mesh to extend coverage to larger areas. 4 Figure 1.4. Networking paradigms: (a) conventional wireless cellular network, (b) multi-hop wireless relay network, and (c) hybrid wireless network integrating cellular structure and multi-hop relay. 5 Figure 2.1. Mutual identification of users: (a) two users who trust each other just exchange their pseudonyms, (b) additional verification involving preregistration, and (c) inspection of a pseudonym by means of PKI infrastructure and trusted third party. 16 Figure 2.2. Evolution from classical to fuzzy and contextual addressing. 26 Figure 3.1. Possible usage scenarios of extended navigation support: (a) typical navigation support, (b) mutual exchange of vehicle positions, (c) additional information about other vehicle states (direction of movement and speed), (d) warnings about possible dangerous situations on the road, and (e) Highway Code violations. 49 Figure 3.2. Basic modes of operation for traffic lights assistance: (a) all-around centered transmission and (b) disjoined transmission separated for the road directions. 53 Figure 3.3. Screen look: (a) after simple filtering, (b) with extended filtering, and (c) LED based (no extended filtering). 54 Figure 3.4. Extended signaling: (a) moments of changing the lights and (b) warnings and alerts. 54 Figure 4.1. IEEE 802 standards related to 802.11 and 802.11s. 111 Figure 4.2. An illustration of an extended service set when multiple basic service sets are integrated with a distribution system, which can be wireline or wireless. 113 xix
- 22. xx LIST OF FIGURES Figure 4.3. Basic mesh network architecture (10–15 access points per gateway). 114 Figure 4.4. Flat mesh architecture using access points that support only single radio omnidirectional antennas. 114 Figure 4.5. Flat mesh architecture using access points that support omnidirectional multiple radios (more than one). Access to client devices is through 802.11b/g. 115 Figure 4.6. An illustration of a layered, multiradio omnidirectional and directional intramesh architecture. 116 Figure 4.7. 802.11s mesh header field introduced in the frame body. 118 Figure 4.8. The 802.11s mesh network architecture depicting connectivity with different types of network. 118 Figure 5.1. IEEE 802.16j network architecture. 123 Figure 5.2. Relay MAC PDU format. 129 Figure 5.3. Relay MAC header. 129 Figure 5.4. Frame structure for nontransparent mode. 133 Figure 5.5. Frame structure for transparent mode (uplink radio resource in time domain). 134 Figure 5.6. Frame structure for transparent mode (uplink radio resource in frequency domain). 134 Figure 5.7. Classification of path management schemes. 140 Figure 5.8. Example of contiguous integer block CID assignment for implicit path management. 144 Figure 5.9. Example of bit partition CID assignment for implicit path management (k = 2, n = 4). 145 Figure 5.10. Bandwidth request (using BW REQ header) in multi-hop relay 802.16j system. 149 Figure 5.11. Bandwidth request (using CDMA code) in multi-hop relay 802.16j system. 150 Figure 5.12. Bandwidth grant with RS-SCH(RS scheduling information) management message. 151 Figure 5.13. Bandwidth request RS polling. 152 Figure 5.14. Bandwidth request with RS-SCH and UL-MAP polling. 152 Figure 5.15. Classification of downlink flow control schemes. 155 Figure 5.16. Downlink flow control in distributed scheduling: localized control scheme. 156 Figure 5.17. Downlink flow control in distributed scheduling: centralized control scheme. 157 Figure 5.18. SS initiates bandwidth request with contention-based CDMA ranging in centralized scheduling relay system—RS transmits MR_RNG-REP with available uplink bandwidth. 160 Figure 5.19. SS initiates bandwidth request with contention-based CDMA ranging in centralized scheduling relay system—RS needs to request extra uplink bandwidth for signaling. 161
- 23. LIST OF FIGURES xxi Figure 5.20. Bandwidth request procedure—RS forwards bandwidth request when uplink bandwidth is available. 162 Figure 5.21. RS interference measure (RS1 and RS4 transmit sounding signals). 165 Figure 5.22. RS interference measure (RS2, RS3, and RS5 transmit sounding signals). 166 Figure 5.23. Intercell active interference measurement. 166 Figure 5.24. Example of repeated R-amble transmission (period = 4 frames, offset = 1 frame). 168 Figure 5.25. Example of one-time R-amble transmission (iteration = 2, active duration = 1 frame, interleaving interval = 3 frames). 168 Figure 5.26. Classification of R-amble transmission based on transmission pattern and usage cases. 169 Figure 5.27. Procedures of neighborhood measurement. 170 Figure 5.28. Access station selection in network entry process. (a) MR-BS serves as the access station. (b) RS serves as the access station. (c) Optional second stage access station selection. 171 Figure 5.29. Network entry procedures. 172 Figure 5.30. Intra-MR and inter-MR handoff scenarios. 178 Figure 5.31. Signaling flows for scanning configuration with distributed scheduling RS. 182 Figure 5.32. Signaling flows for scanning configuration with centralized scheduling. 183 Figure 5.33. Handoff signaling flow. 185 Figure 5.34. Optimized handoff with intracell context transfer (serving station initiated). 187 Figure 5.35. Optimized handoff with intercell context transfer (serving station initiated). 187 Figure 5.36. Optimized handoff with intracell context transfer (target station initiated). 188 Figure 5.37. Optimized handoff with intercell context transfer (target station initiated). 188 Figure 5.38. Mobile RS handoff procedures. 189 Figure 5.39. Classifications of HARQ operations in IEEE 802.16j. 197 Figure 5.40. Encoded feedback Cx to indicate where the packet error occurs; C0 implies data received without error; Cx implies data error is x-hop away from the MR-BS. 200 Figure 5.41. Downlink HARQ in nontransparent mode: encoded feedback in uplink acknowledge channel (UL ACKCH). 201 Figure 5.42. Topology for the downlink HARQ transmission example and UL ACKCH feedback (ACK/NAK). 201 Figure 5.43. Centralized scheduling downlink hop-by-hop HARQ in transparent mode: successful transmission. 203
- 24. xxii LIST OF FIGURES Figure 5.44. Centralized scheduling downlink hop-by-hop HARQ in transparent mode: error in relay link. 203 Figure 5.45. Centralized scheduling downlink hop-by-hop HARQ in transparent mode: error in access link. 204 Figure 5.46. Centralized scheduling downlink RS-assisted HARQ in transparent mode: successful transmission. 205 Figure 5.47. Centralized scheduling downlink RS-assisted HARQ in transparent mode: errors in both access link and relay link. 206 Figure 5.48. Centralized scheduling downlink RS-assisted HARQ in transparent mode: error in relay link but successful reception in monitoring RS. 206 Figure 5.49. Centralized scheduling uplink HARQ in nontransparent mode: successful transmission and ACK. 208 Figure 5.50. Centralized scheduling uplink HARQ in nontransparent mode: error and NAK. 209 Figure 5.51. Centralized scheduling uplink HARQ in transparent mode: the MR-BS receives forwarded data from the RS. 210 Figure 5.52. Centralized scheduling uplink HARQ in transparent mode: the MR-BS receives data directly from the SS. 210 Figure 5.53. Network topology and delay values in a multicast and broadcast service example; the waiting time in each hop depends on the network topology and latency values. 213 Figure 5.54. Example of synchronous multicast and broadcast transmission timing. 215 Figure 5.55. RS grouping in IEEE 802.16j system. 216 Figure 5.56. Macrodiversity transmission schemes and parallel transmission schemes in RS grouping (a) downlink macro diversity transmission; (b) uplink macro diversity transmission; (c) downlink parallel transmission; and (d) uplink parallel transmission. 218 Figure 6.1. LTE relay architecture and terminologies. 222 Figure 6.2. Example of resource partitioning in the FDD LTE relay system. 225 Figure 6.3. Example of resource partitioning in the TDD LTE relay system. 225 Figure 6.4. MBSFN subframe configuration in the access link (MBSFN subframes are the unused time gap to avoid interference). 226 Figure 6.5. Protocol stack for Un interface user plane. 229 Figure 6.6. Protocol stack for Un interface control plane. 230 Figure 6.7. Interfaces in LTE relay system architecture. 230 Figure 6.8. Protocol stack for S1 interface user plane (S1-U). 231 Figure 6.9. Protocol stack for S1 interface control plane (S1-MME). 232 Figure 6.10. Protocol stack for X2 interface user plane (X2-U). 233
- 25. LIST OF FIGURES xxiii Figure 6.11. Protocol stack for X2 interface control plane (X2-CP). 234 Figure 6.12. RN startup procedure Phase I. Relay node attaches as UE. 235 Figure 6.13. RN startup procedure Phase II. Relay node attaches as RN. 236
- 26. LIST OF TABLES Table 2.1. Comparative Summary of Issues and Solutions in Traditional and Ad-Hoc Multi-hop Networking 39 Table 4.1. IEEE 802.11 WLAN Major Releases and Features 112 Table 5.1. Signaling Messages for RS Neighborhood Discovery 171 Table 5.2. Signaling Messages Used in Handoff and Mobility Management 190 Table 5.3. Feedback Coding for Multi-hop HARQ Acknowledgment (ACK) and Negative Acknowledgment (NAK) 198 Table 5.4. Signaling Messages for Multicast and Broadcast 212 Table 5.5. Signaling Messages Used in RS Grouping 219 xxv
- 27. Introduction Nowadays, a global trend is to make our lives easier. To reach this goal, we freely apply new technologies to develop personal, organizational, and social solutions.We even create new technology domains and their applications, such as cellular telephony or Internet.And it looks like that this trend is only going to accelerate, as new technologies lead to new multidisciplinary innovations with a multiplier effect. The rapid change is akin to what Arthur C. Clarke described as “magic”—any sufficiently advanced technology is indistinguish- able from magic (Clarke, 1962). And humans, for the most part, have begun to believe in that magic such that with technology and innovation almost everything is possible. With the mass introduction of, first, the Internet, and, now, cellular tele- phony, a new need has arisen to be able to communicate with everybody (or everything), at anytime, from anywhere, including access to the Web.“Magical” mobile communication has been accepted as a norm around the world, and this nomadic lifestyle has prompted a serious look at the business and personal environment. However, the “magic” is unfortunately constrained by several technical and economic obstacles. Even if we do believe that unrestricted com- munication is a must, we are still faced with many challenges, for example, poor signal quality and range, and high calling costs. Satellite phones would probably work better to provide universal coverage (e.g., in rural and moun- tainous regions), but the cost will be prohibitively high. Similarly, a bigger battery would substantially reduce the need for frequent recharging, but it is going to severely impact portability. As we become aware of our continuously expanding needs and expecta- tions, we naturally tend to ignore the limitations. In general, two ways are possible: either we simply wait for an introduction of a new technical/ organizational/social solution, new infrastructure, device, and so on, or we try to adapt the existing solutions for new challenges, even if this is a temporary solution; alternatively, we apply a mixed approach—first we try to accomplish the best from the existing solutions, and later search for a new solution to better fulfill our needs. WiFi, WiMAX, and LTE Multi-hop Mesh Networks: Basic Communication Protocols and Application Areas, First Edition. Hung-Yu Wei, Jarogniew Rykowski, and Sudhir Dixit. © 2013 John Wiley & Sons, Inc. Published 2013 by John Wiley & Sons, Inc. 1 1
- 28. 2 Introduction This book is devoted to applying such mixed approaches to mobile com- munication and internet access with the main objective to significantly improve coverage and minimize cost. Recently, wireless computer networks, such as WiFi and WiMAX, on the one hand, and mobile communication, such as general packet radio service/enhanced data rate for global evolution (GPRS/ EDGE), high speed packet access (HSPA), and Long Term Evolution (LTE), on the other hand, have opened up new possibilities to meet the objectives. However, to build such a network, significant investment in the infrastructure is required, not to mention of the physical restrictions (such as the ability of the radio signals to penetrate through physical structures). From the organizational point of view, the connected equipment (mobile stations) must authorize itself prior to accessing the network, and there is a serious issue of potential denial of service attack between a “server” (i.e., network element serving the client devices) and a “client.” The advent of ad-hoc and multi-hop networking has only compounded the problem. A mobile ad-hoc network (MANET for short) is defined as a self-organized set of wireless, mobile nodes with no fixed topology of connections. In general, wireless mesh network can be of two types (Fig. 1.1): MANET and infrastructure-based immobile network. MANETs are typically peer-to-peer Figure 1.1. Examples of (a) mobile ad-hoc (infrastructureless) mesh network and (b) immobile (infrastructure-based) mesh network. WiFi AP (a) (b) WiFi AP Wireline or wireless backhaul to ISP Internet/Telecom infra Internet/Telecom infra
- 29. Introduction 3 networks with mobile client devices communicating with each other directly or through other nodes in multi-hop configuration (Fig. 1.1a). Here client nodes may function as routing nodes for others that are not within each other’s communication range. In immobile wireless mesh network, the access radio nodes and gateway nodes are stationary, and the client devices connect to the access node (Fig. 1.1b). MANET organization may vary in time—nodes are being connected and disconnected, they replace their point of connection (their neighborhood evolves), and dynamically adapt themselves to the topol- ogy changes. As a matter of fact, nothing is fixed; in contrast to classical net- working,a MANET node may disappear at anytime,causing serious disruptions to the neighboring nodes. Furthermore, routing of the information must be planned in a dynamic manner so as to be able to deal with the evolving network topology (the route for the outgoing packet and the incoming packet between a pair of nodes may be different, as the topology may change even during the period of a single transmission). When we speak about MANETs, we think about mesh networking. A wireless* mesh network can be in general configured as a hierarchical network made up of home area network (HAN), Neighborhood Area Network (NAN), and wide area network (WAN), each utilizing the most suitable wireless tech- nologies for their needs. For HAN, IEEE 802.11- and IEEE 802.15.4-based ZigBee (ZigBee Alliance, 2012) are thought of as most suitable. In the major- ity of cases, a single access point (AP) or ZigBee host is sufficient in the home scenario. If the source and destination nodes do not reside within the same NAN, the traffic from the various HANs is routed to one or more gateway nodes that backhaul the traffic utilizing high speed mobile data technologies, such as 3G,HSPA/HSPA+,LTE,LTE-A,orWiMax (3GPP Specifications,2012; IEEE Wireless MAN [WiMax], 2012; WiMax Forum, 2012). The preferred solution to cover a wide area (resulting in a NAN), such as a neighborhood, a campus, or a city is to use IEEE 802.11x WLAN (aka WiFi) in mesh configu- ration. Figure 1.2 shows a generic wireless mesh network depicting the various scenarios. Figure 1.3 shows the use of lower frequency white spaces between the TV channels (which is at much lower frequencies than 2.4 GHz) in the ultra-high frequency (UHF) band (470–890 MHz) to create longer distance Internet connections that easily penetrate through the physical obstructions. These are still unlicensed and therefore their use is free and similar to WiFi and Bluetooth. This type of networking technology is called “Super WiFi” by the Federal Communications Commission (FCC) (Regulators, 2012; Segan, 2012). It should be noted that there is no similarity with the WiFi technology, and the use of “Super WiFi” is confusing and controversial with the Wi-Fi Alliance (WiFi, 2012; US regulators, 2012). Traditionally, wireless network design is based on the centralized architec- ture where the base stations control the operation of the wireless services * To simplify the description, we consider wireless connections only.
- 30. 4 Introduction Figure 1.2. Use of long range WLAN (Super WiFi) mesh to extend coverage to larger areas. Neighborhood (i.e., mesh clouds) 0–5 are disjointed (nonoverlapping). Neighborhood 0 Neighborhood 2 Neighborhood 3 Neighborhood 5 Neighborhood 4 Internet Internet GSM access point with WiFi or WiMax/3G/4G Ackhaul with or without mesh networking (NH 5 has wireline termination and the customer chooses to directly connect to the internet.) Neighborhood 1 GSM link WiFi/ WiMax/ 3G/4G WiMax/3G/4G Tower WiFi router Wireline link Wireless link Nomadic/mobile user with WiMax radio Multiple overlapping WiFi Mesh clouds WiFi access gateway with or without WiMax/ 3G/4G Figure 1.3. Use of long range WLAN (Super WiFi) mesh to extend coverage to larger areas. Inter village/campus wireless link Village Node WLAN Mesh with fiber backhaul Headend Fiber backhaul 2- to 5-km links typically Village Node WLAN Mesh with WiMax/3G/4G backhaul WiMax/3G/4G Headend WiMax/3G/4G backhaul 2- to 5-km links typically
- 31. Introduction 5 delivered to subscriber stations. In the conventional wireless cellular architec- ture, a base station is the centralized controller of each cell, as shown in Figure 1.4a. The base station transmits and receives data packets and signaling mes- sages to and from subscriber stations through a one-hop direct wireless link. On the other hand, a multi-hop relay wireless paradigm has emerged in recent years. In multi-hop wireless relay networks, wireless nodes may transmit and forward packets through one or several wireless relay hops, as shown in Figure Figure 1.4. Networking paradigms: (a) conventional wireless cellular network, (b) multi-hop wireless relay network, and (c) hybrid wireless network integrating cel- lular structure and multi-hop relay. (a) (b) (c) Base station (BS) Base station (BS) Mobile station (MS) Relay station (RS) Mobile station (MS) Relay station (RS) Mobile station (MS)
- 32. 6 Introduction 1.4b. In this multi-hop relay network configuration, a distributed design approach may be applied to enable multi-hop relay signaling and data trans- port.A third wireless network paradigm integrates the previous two approaches as shown in Figure 1.4c. Both direct one-hop wireless connections and multi- hop wireless relays are present in this hybrid architecture.This hybrid wireless network architecture leverages the benefits of both the conventional cellular architecture and the multi-hop relay architecture to provide efficient central- ized wireless network control and flexibility of multi-hop relaying. As the hybrid architecture could take advantages of both the conventional centralized cellular architecture and the emerging relay architecture, there are several design benefits that could be exploited. Some of the key advantages of this hybrid wireless multi-hop relay architecture are as follows: • leveragedbenefitsofcellulararchitectureandmulti-hoprelayarchitecture • extended wireless network coverage at cell boundary • enhanced signal reception quality and throughput • improved load balancing • flexible deployment with fixed or mobile relay stations. A still-growing trend is to spend large sums of money on the development of ad-hoc and multi-hop technologies. However, it is worth noting that these ideas are not quite new.The very first research on these topics was undertaken in the late 1960s. Then, ALOHA protocol was proposed to control the access to telecommunication channels.Although it considered only stationary nodes, communicating in a single-hop mode, it was the first step toward spontaneous and unrestricted networking. In 1973, DARPA initiated the PRnet (Packet Radio Network) project based on multi-hop transmission. This proposal clearly showed that using multi-hops may substantially extend the network range, improve efficiency (especially by division and parallel transmission of signal parts), and reduce energy consumption. Nowadays, MANETs are capable of multi-hop information routing even when the network topology and traffic are dynamically changing, while employing narrow and temporal channels. Several companies now offer global solutions, prime examples being Intel, CISCO, Mitsubishi, BMW, Nokia, and Deutsche Telecom. Despite tech- nical, organizational, societal, and legislative issues (some of them discussed in this book), the global trend is clear. Using ordinary nodes as routers sub- stantially improves network range and efficiency. Each device already con- nected to the network may in turn become an access point for other devices, even those not operating directly in mesh topology. The replacement of “one- to-many” access mode by “many-to-many” opens up new connection and transmission possibilities. Local instead of long-distance communication reduces network traffic and improves coding and noise/error reduction while also eliminating interference among devices and improving radio bandwidth sharing. Local communication also protects the environment—less power is
- 33. Introduction 7 needed to transmit the signals at a short distance. These advantages compen- sate the necessity to use own energy for serving other network nodes. As in other modern technologies, the army was the first big client of mobile ad-hoc, multi-hop networking. A need for efficient local transmission among the soldiers at the battlefield seems to be the ideal case for testing networking mode needing no “central” and/or “server” node. Even if marked as “top secret” for obvious reasons, the technologies had to migrate, sooner or later, to the civilian world. Businessmen see themselves as “business soldiers,” and they have similar needs. And even ordinary users would welcome network efficiency and range. So why not adapt the army-related solutions to every- body? Linked with personal firewalls and ciphering (virtual private network- ing, VPN), ad-hoc and multi-hop access is a need in many situations at home and at work. In addition, the network operators may significantly improve customer satisfaction. The users themselves may also apply mesh networking to new application areas, including self-managed “community” networks outside the control of the network operators/administrators. Problems and questions emanating due to the success of ad-hoc and multi- hop networking create their own challenges. This book is intended to address both the technologies of mesh and ad-hoc networking and quality of service issues. The book adopts the following approach. First, potential application areas of ad-hoc and multi-hop networking are discussed, with emphasis on privacy, security, anonymity, trust management, traffic filtering, information searching and addressing,quality of services,personalization,and other aspects. We try to enumerate the biggest potential application areas, including telemat- ics, public transportation, telemedicine, environment protection, public safety, marketing and shopping guidance. Last but not least, in this part of the book, we discuss the most important economic aspects of multi-hop and ad-hoc networking, both from the point of view of the network provider/operator and the end user. Second, we describe several technical aspects of multi-hop networking while limiting the scope to three key networking technologies: WiFi (IEEE 802.11*), WiMAX (IEEE 802.16*), and LTE. Starting from the introduction of network architecture and basic terminology, we move on to discuss some important technical details, such as routing and node addressing, MANET multi-hop extensions, such as WiFi mesh networking 802.11s, enhancements to physical and media access control (MAC) layers for 802.16j protocol, and recent proposals toward efficient LTE relaying. The book is addressed to a wide audience, from students of computer science and related domains to engineers and system designers. The book introduces the emerging multi-hop relay wireless networking technology and its applications. An engineer, who works for a wireless network service provider, would benefit from the complete coverage of the wireless multi-hop mesh technologies. The book not just covers technology aspects, it also addresses applications, as well as some important architectural issues, such as searching for
- 34. 8 Introduction information in local ad-hoc networks, extended addressability for both the network nodes and the information published via/by these nodes, anonymous and ad-hoc access, and so on. In addition, the book covers several integration issues, such as integration with backhaul connection, and WiFi and WiMAX multi-hop relay integration. Several deployment scenarios and applications are also illustrated.Engineers and technical managers could realize the deploy- ment options and the trade-off between application scenarios and the technol- ogy to be chosen. The book covers a wide range of system architecture and protocol design issues in WiFi, WiMAX, and LTE multi-hop mesh networks. Readers would get a head start in the latest WiMAX multi-hop relay networking technology and be ready for the future research inWiMAX-based multi-hop relay research and development (including IEEE 802.16j and the multi-hop relay extension for the next-generation IEEE 802.16m). Engineers would find the various system architecture design trade-offs useful. To research and develop the future mesh multi-hop relay technologies, researchers and engineers would benefit by the design considerations of various system protocol components, such as mobility management, multi-hop relay path management, location management, paging protocol design, network entry process, power efficient design, medium access control protocol design, service flow QoS management, system auto-configuration, and so on.
- 35. Architectural Requirements for Multi-hop and Ad-Hoc Networking In the introduction, we briefly discussed several aspects of ad-hoc and multi- hop networking. The discussion was mainly devoted to possible implementa- tions of physical and logical connections in an ad-hoc network of devices. However, taking into account a wider point of view, there are many other important issues in ad-hoc networking. Let us assume a user is trying to get useful information from a network. Before anything else, there is one impor- tant task—that is, how to pick an access device. For example, a user may decide to use a smartphone, a tablet, or a notebook, and so on. However, in this book, we will not worry about the choice of a device, since there exists a wide spec- trum of devices to choose from. Instead, we are going to concentrate on other ad-hoc user activities, mainly: ad-hoc authorization or authentication mecha- nism, including a trade-off between the anonymity and the security, ad-hoc searching for an information/service, including fuzzy queries, and ad-hoc choosing and accessing the just-found information/service. In the remainder of this chapter, we are going to discuss these topics after a general discussion on the needs and expectations, on the one hand, and pos- sible restrictions and limitations, on the other hand, of ad-hoc and multi-hop networking. 2.1. WHEN AND WHERE DO WE NEED AD-HOC NETWORKING? Let us leave aside networking for a while and raise a more general question— when and where do we need ad-hoc activities? At home? Probably not— everyday activities are usually quite stable and repeatable.At work? For most jobs, probably not, because the work environment is pretty well provided. Aside from the earlier examples, we all have to travel everyday between home and work. We have to do incidental and weekly shopping. We have to visit local administration offices from time to time, we go places on holidays, and many more.Most of these activities are usually performed in an ad-hoc manner. While traveling, we also interact with other drivers, pedestrians, and road WiFi, WiMAX, and LTE Multi-hop Mesh Networks: Basic Communication Protocols and Application Areas, First Edition. Hung-Yu Wei, Jarogniew Rykowski, and Sudhir Dixit. © 2013 John Wiley & Sons, Inc. Published 2013 by John Wiley & Sons, Inc. 9 2
- 36. 10 Architectural Requirements infrastructure. What is common with all these activities? First of all, we use our senses, for example, sight, smell, and hearing. And we do it only locally, as our senses work only in a local environment. Second, usually, we do not have enough information how to proceed further, and we are continuously looking for more hints and instructions. Third, usually, we are overloaded with nones- sential information that must be filtered out to achieve better results on what matters most. Now, going back to networking, at home and work, we usually have access to a stable network connection, with classical login, user names, passwords, and so on, so ad-hoc networking is not a necessity. And what about the rest of our activities? It looks like there is a place for ad-hoc networking.After all, ad-hoc networking is a natural extension of ad-hoc activities mentioned earlier. For example, we would like to use our smartphone to take a look into a part of a road in front of us to discover the reason for a traffic jam ahead of us. Naturally, we use our sight; however, if it is too far and we are not able to leave our car, we would like to ask someone who is better informed, for example, a driver at the very beginning of the traffic jam. So, why not to ask this driver for a photo to be sent via a local (ad-hoc) network to our smartphone? Why not ask him by a Skype call? However, we neither know the phone number nor an IP address of this driver’s device. So, we are forced to establish an ad-hoc connection with the drivers in a local neighborhood to reach the driver of interest, hoping some of them are better informed. Thus, there is certainly a place for ad-hoc and multi-hop networking. Let us now try to answer the question raised in the title of this section: when do we apply ad-hoc networking? The answer is simple—for all our everyday ad-hoc activities, as much as we can: traveling, shopping, meeting with inciden- tal people, reacting in impromptu situations, and so on. The second question is: where? The answer is similar—everywhere we usually perform our ad-hoc activities. And even at home and at the workplace, we can apply ad-hoc net- working. For example, the “smart buildings” can provide sophisticated infra- structure to improve the way of interaction with humans. Ad-hoc networking may be used for dynamic adjustment of human possibilities, especially for incidental users—imagine a person being guided to an office via a personal handheld device, without having to ask anyone. Or simply imagine that you use your mobile as a TV pilot, working with all kinds of TV sets irrespective of where you are. Also, at work, especially in dynamic environments, for example, a hospital, ad-hoc networking may substantially improve access to the information. Where am I? Where is the nearest doctor to help me? How do I find quickly something of interest? If we exclude mobile broadband (e.g., 3G and 4G), the solution is ad-hoc networking because it is readily configured dynamically, for spontaneous situ- ations, interactions, mainly outside the traditional networking places such as home and workplace. What is also interesting to note is that the ad-hoc inter- locutors are usually anonymous, because they want to stay anonymous, or because we do not have technical and organizational means to authenticate
- 37. When and Where Do We Need Ad-Hoc Networking? 11 them.“Anonymous” means not only that we cannot authenticate a person, but it covers also end-user devices and their technical capabilities, connection type and bandwidth, and so on. Spontaneous place and time of access means dynamic binding to unknown devices of others. Thus, it is very important to collect some indirect information about the interlocutors—the device name and type (if broadcasted), geographical position (if available), connection bandwidth, and so on. Such identified context of interaction is very important and will be discussed in detail later in this chapter. In the rapidly changing socioeconomic environment, where the pace of information exchanged has accelerated, we would like to be “always con- nected.” For example, what happens if an important e-mail I have been waiting for arrives while I am driving a car? A mobile phone partially fulfills such a requirement, but only for human-related interactions. What about possible automatic interactions with the devices nearby or far away? For example, an important road sign may interact with our personal navigation device, to send a warning or even slow down our vehicle. A shop we are just passing by may send an advertisement about some goods we are looking for, or we may simply be reminded by the refrigerator that we have to buy bread and milk before reaching home. “Always connected” does not mean “always available” and “sharing every- thing.” Usually, people tend to protect their privacy with the fear of misuse by others. Thus, for ad-hoc activities, it is necessary to put in place effective veri- fication that the information is coming from a trusted source. Even if we do not know the nodes, we would like to share information with some of them, and we would like to trust this information. Similarly, when we ask someone at the street for assistance (e.g., direction to a destination), we somehow trust the person we have chosen to start the conversation. If, however, suddenly we discover that something is wrong (e.g., the questioned person is not pretty sure or we are not convinced that the pointed direction is correct), then we simply try to find another person. Likewise, in an ad-hoc network, we may ask several nodes for the information, compare the received information, and then choose the most probable or “best” answer.* The “always connected” mode of networking leads to so-called “nomadic” way of living. As nomads on the desert, we travel from place to place, while still staying connected with the network. And as nomads, we are a part of the society, even if we are far away from each other. As nomads have a common culture and language, the connected people also have a common way * Please note here one very important difference between real-world ad-hoc interactions and ad-hoc networking. In the real world, while asking someone for a way, we do not expect that the interlocutor is lying—the liar would not stay all the time just to meet us and tell us the wrong way. However, we may easily imagine a device waiting somewhere and cheating the ad-hoc interlocutors—a device “born to lie.” The only goal of such a liar-device would be to wait and cheat, that is, providing falsified local advertisement for “the best restaurant nearby.” Thus, we must be pretty aware while adopting some well-known examples of ad-hoc conversations to ad-hoc networking—these are two quite different environments.
- 38. 12 Architectural Requirements of communicating and interacting with each other. Nomadic communication is very close to ad-hoc networking, but should connect to a stable network through some type of authentication. Even if nomads interact with random people in an ad-hoc manner, nomadic nodes would probably also want to connect with stable, nonanonymous, persistent connections. The next question that needs to be answered is “How?”. There are several technical, social, and organizational problems to be solved while applying ad-hoc networking for ad-hoc everyday activities. First, how do we determine the detailed addresses of our interlocutors? To make the problem even more difficult,we do not know the interlocutors themselves—they are as anonymous for us just as a person on the street or a driver in a car nearby waiting for a green light. So, the challenge is how to solve the problem of anonymity and knowing the exact address. Second, we do not know what are the technical possibilities to provide an interaction, for example, type of network, available bandwidth, capabilities of the end-user device, and so on and so forth. Then, the next problem arises—how to send the needed information: exact format, access mode, restrictions, and so on. Third, we have to choose a single inter- locutor exactly in the same way we are going to choose a single person on the street to ask for help. Even if we start with broadcasting a request for an interaction, sooner or later, we have to choose one connection, hoping that it would be the best one. This raises another issue of how to filter out the best information sources. Fourth, our interlocutor may be not interested in sharing information with us. So, the next issue to address is how to establish a connec- tion and how to improve mutual trust in an environment where all the users (and their devices) are unidentifiable.All the challenges in ad-hoc networking will be discussed in detail later in the next several sections. 2.2. WHEN DO WE NEED MULTI-HOP? HOW MANY HOPS ARE SUFFICIENT/NECESSARY? There is one key technical issue we have not introduced so far—multi-hop connections. Sometimes, for example, at the boundary of a network, I cannot connect, but my neighbor probably can. So, why not use my neighbor’s device as a relaying node to the rest of the network? In short, multi-hop networking means using local connections in the neighborhood and cascading them to reach the destination node, which may otherwise not be reachable directly. Multi-hop means ad-hoc routing of information via several intermediate nodes in the network. This aspect of ad-hoc networking has been already discussed in the previous chapters. However, that is not enough, and issues of security and privacy must be addressed. In single-hop networking, the question of security and privacy is a matter between two corresponding hosts, assuming that the fixed network infrastructure is trusted. Even if we do not trust inter- mediate nodes, we can always use VPN (virtual private networking) (VPN, 2012) to assure privacy and security. However, in multi-hop, we try to use some
- 39. Anonymity versus Authorization and Authentication 13 nontrusted access devices of other users as intermediate nodes. Now, if we use VPN-equivalent techniques, why should an intermediate node trust that the network traffic is not going to violate common rules? And, vice-versa, if non- encrypted information is sent to intermediate nodes to convince them that the source node is obeying the rules, who will guarantee that the intermediate nodes will not change or block the information? Moreover, how do we balance a natural behavior of blocking others’ traffic, for example, to conserve the battery power or to save on the bandwidth resources? A discussion on these topics will be provided in the remainder of this chapter. Let us next discuss the question: how many hops are sufficient or necessary? The simplest case is that of one access point and two-hop networking— everybody connects to such an access point in the ad-hoc manner, but the access point itself is connected to the fixed network.There are several reasons for such nondirect network utilization—some of them are purely technical (limited signal, no required communication module, etc.), while some of them are financial (high costs of direct networking, e.g., HSPA [high speed packet access] [HSPA, 2012], when compared with ad-hoc networking, providing free access).Another reason is practicality when most of our traffic is local and we connect to the wide network at random,for example,to synchronize our e-mail boxes. For example, all the passengers of a city bus may enjoy Internet con- nection, performing ad-hoc communication with an onboard device that in turn multiplexes the traffic to an outcoming WiMAX channel. Of course, the passengers may communicate locally as well among themselves through their access devices. A similar use case can be found with the passengers on an airplane where the Internet connection is made via a satellite link. If we consider short-range networking, it is soon discovered, however, that the two-hop technique is not sufficient in many cases, and we have to extend the networking range by using other devices as intermediate relays. However, as already discussed, from the technical point of view, it is not advisable to apply more than three to four hops for a single transmission, as the overhead involved to compute the route and to find the return path to send a response back is extremely huge. In addition, the field tests have shown that on average, the throughput drops by about one-half with every additional hop. Therefore, in this chapter, we limit our discussion to only two or three hops to access a wide-area network gateway node, while reserving the discussion on more than three hops to special scenarios, such as propagation of a security alert, and first responders in natural emergency cases. 2.3. ANONYMITY VERSUS AUTHORIZATION AND AUTHENTICATION As previously discussed, ad-hoc activities are usually related with the anonym- ity. Going back to the example of connecting with a random person for finding directions, it would be a bad idea to start such an activity by asking the person
- 40. 14 Architectural Requirements for his/her name or other credentials. Moreover, we usually do not introduce ourselves when asking a question to a random person. Conversely, if we are going to visit (or call) an office, we start the conversation by introducing our- selves. This is not a requirement, but we do this simply as a common courtesy. Even if the other person provides his or her name, it is difficult to authenticate it. However, there are some situations we have to authenticate ourselves, for example, when paying by a credit card (authentication by photo/signature/PIN, etc.). The previous common behaviors tell us that we prefer to remain anony- mous as long as we can, providing our identity only when required. Such interaction behaviors in real life are not a problem. As everybody interacts locally, the identification is made with the help of our senses, mainly visually. However, it becomes a problem when we apply these approaches to ad-hoc networking. There are several reasons for this. First, in any network, if we would like to receive information, we (or rather our access devices) must be identified by a unique address. In the absence of the destination address, no information can be routed to it. However, propagating the address informa- tion means losing anonymity. Second, billing to an anonymous user for the use of the network resources is not possible. Another challenge is how to group users in catalogues and other address books so that they are searchable? Perhaps the most important question is how to trust an anonymous user. Finally, once introduced, how can we simplify the identification process when we interact with the same user for the second time (“Do we know each other? Have we met before?”)? We cannot overlook the problem of dealing with those anonymous users who do not behave well toward others in the network. Such phenomenon is well known in the Internet, for example, anonymous discussion sooner or later leads to insults aimed at discussion partners and anonymous comments in public portals, which are sometimes very unfair. Similarly, some WWW servers propagate information that is not correct and some people take it as the right information. There are no mechanisms to force authors of such incorrect information to change it. Even if someone introduced the corrected version of this information using a different server, this correction will be either not known to those who were deceived, or there will be no independent “judge” to declare which version is correct. Such problems in the scope of ad-hoc networking are even more serious, as the network configuration and the local- ization of the information sources may vary—the erroneous or falsified infor- mation may be propagated time and again from different places and in different forms, authorized under variable identities and without any control. Since the information flows through multiple nodes, the destination node has to learn about the fraudulent node going all the way to the source. Thus, even if the users wish to remain anonymous, there should be an iden- tification mechanism provided, shared by all the users.An open question is: to what extent do we have to violate the anonymity? Should full name, address, and so on, be stored somewhere and made accessible on request? Probably not. Maybe a user-chosen identifier, a pseudonym, is enough? Or a neutral
- 41. Anonymity versus Authorization and Authentication 15 identifier, such as a MAC address of the networking card or GSM phone number? Or a mixed approach—full authentication information is stored in a secret place, linked with a pseudonym? Such information is accessible under special conditions, for example, by police or medical personnel.This approach is similar to the process of registration of vehicles—each vehicle is equipped with a license plate, publicly accessible. However, a link between the license plate number and the user of the car is hidden in a government database, to be accessible at request after getting special permissions. It looks like the last approach is optimal, with some extension, involving a two-step authentication process. In the first step, an ad-hoc user, while con- necting to a local network, propagates his or her pseudonym. The pseudonym may be chosen ad-hoc, only for a single interaction, or permanently chosen with the option to change it later. One may expect that for most ad-hoc activi- ties, the pseudonyms would be stable, for example, as in the case of the e-mail addresses. However, as long as the user uses the same e-mail address, the address is stable, but once the address is changed, the user is treated as being new to the system, without any binding with the previous e-mail account. On the one hand, most people would trust this method of identification (an “opti- mistic approach”),but on the other hand,some users would change the account quite frequently (e.g., those distributing spam via e-mails). Under these cir- cumstances, it becomes the responsibility of the other user to detect such fraud and react accordingly. It should be noted that this phase does not require any centralized database for storing users’ pseudonyms. In the second step, when better authentication is needed, everyone is free to register his/her pseudonym in a common database, to be accessible by others. The access may be divided into provisional identification (“yes, such a user is registered, but you are not entitled to get any authentication infor mation”) and full identification (providing all the identification data at request). To improve trust in the service, PKI (public key infrastructure) encryption with electronic signature (a public key/PKI certificate potentially serving as a unique identifier/pseudonym) (C. Adams and S.L. Lloyd, 2002) may be applied. Note, however, that by introducing such PKI-based authorization center (Fig. 2.1), we somehow break the principle of ad-hoc networking, because such a center must be global, operated by a trusted third-party institution. The question that needs to be asked is: Could it be a local network operator or dedicated servers, such as for example, a DNS service (DNS, 2012) in the fixed network? Figure 2.1 presents two basic implementations of semi-anonymous identi- fication based on pseudonyms, with and without PKI support. In the first case (Fig. 2.1), users just exchange pseudonyms without any additional verification. All the users trust each other, with the expectation that no user would use a pseudonym of someone else. As proven by the history of Internet, such approach has worked surprisingly well for open-application environment, for example, the Usenet and the various discussion groups. However, one must note that this approach may not work well for ad-hoc communication.
- 42. 16 Architectural Requirements In the second case, to provide secured and trusted, yet anonymous identi- fication of user pseudonyms, PKI infrastructure is used based on digital cer- tificates issued by a trusted third party. The process of identification is split into two phases. During the first phase (Fig. 2.1b), each user generates a pair of PKI keys (private and public) to the third-party trusted authenticator (a trustee).The trustee sends back a certificate with both the pseudonym and the public key, encrypted by means of the private key of the trustee. Anytime the user is about to send a “trusted” message, he/she must encrypt his/her message (or just its digest) by means of his/her private key, and then send it together with the certificate (Fig. 2.1c). As the new message arrives, the receiver is able to decrypt the certificate (using public key of the trustee), decrypt the message (using public key from the certificate), and verify the pseudonym. Once the message is decrypted, the complete transmission and the sender are verified and thus treated as trusted. Note that the trustee does not have to be contacted directly when receiving the messages—the fact that it could correctly read the encrypted message is a proof by itself that the sender and the message have been authenticated. The earlier-proposed identification database may be extended to include the organizational and utilization aspects as well.To achieve the first objective of improving efficiency, rather than having a single system for the whole network, a hierarchical set of smaller services should be provided that are hierarchically connected similar to well-known DNS utility (domain name service) of the Internet. Consequently, the networking traffic linked with identification may be substantially closed in a local environment.Local caching (similar to DNS caching) of frequently used identifiers would significantly improve the efficiency as well. Taking a wider look for the potential use of the identification service, one may extend the identification information stored in the database by additional Figure 2.1. Mutual identification of users: (a) two users who trust each other just exchange their pseudonyms, (b) additional verification involving preregistration, and (c) inspection of a pseudonym by means of PKI infrastructure and trusted third party. (a) (c) (b) User A encrypted message certificate A User B User A pseudonym A Third-party trustee certificate A User B User A pseudonym A
- 43. Security and Privacy in Ad-Hoc Networks 17 dynamic parameters, such as the current geolocation of the access device and the current state (on/off, operational/not in operation, network bandwidth, etc.). One can include the user-chosen parameters as well, such as the color of the car, model and make of the car, usage information, and so on. The global center for identification may be turned into a global center of trust, including the rating of trustability for each user specified by such param- eters as his/her networking “credits,” others’ comments, warnings, and so on. In the next few sections, we will apply the earlier-described extended iden- tification database for contextual searching and other ad-hoc services. 2.4. SECURITY AND PRIVACY IN AD-HOC NETWORKS As is well known, the issue of trade-off between security and privacy is a complex one. For many reasons, we have to continuously choose between better security and overall system protection (from systems point of view), and improved privacy (from user’s point of view). More the system is secured, less private the information becomes. A totally secured system means that every- thing is known and inspected by the system, and thus there is no place for privacy protection. And, vice versa, if everything is confidential about users, nothing can be inspected by the system to improve security—total privacy means no security regulations at all. Thus, a balance is needed—the system should be as secured as possible, while still keeping the privacy at a reasonable level. Note, however, that what is “reasonable” for some users may not be acceptable to others. Trade-off between security and privacy is even more challenging in ad-hoc networking than in traditional networking. There are several system mecha- nisms and services to improve security, namely strong authentication and authorization (involving usernames, passwords, tokens, etc.), network activity monitoring, continuous logs for crucial data (e.g., times of network connec- tions, information changes inside a database, and file access). These mecha- nisms are widely applied at different levels of system organization—locally on a single computer (e.g., user accounts and file access log), for a local area network (e.g., server access logs and authorization log for roaming users), and globally for many computers (e.g., network configuration change log and Inter- net access log). Note, however, that all these mechanisms require either strong authorization of users, or unique identification of hardware, or software (usually network nodes), or both. This is not the case for ad-hoc networking, for many reasons. First, as already discussed in the previous section, ad-hoc users tend to remain anonymous. Thus, strong authentication is not possible or at least restricted (e.g., addressed only to those users who performed full registration). Second, it is quite hard to proactively monitor network traffic or store logs of networking activity, as there are no nodes specialized toward such actions. When every node is connected in an ad-hoc manner and the network configuration is unstable, no monitoring and logging is possible.
- 44. 18 Architectural Requirements Consequently, in ad-hoc networking, security is usually very limited. Thus, naturally, the privacy will take the front seat, allowing users to remain not only anonymous, but also practically inviolable. This theoretically leads to a situa- tion where every node is a separated island in the network, totally protected and inaccessible by other nodes. Moreover, as the potential interlocutors are not able to verify the trustworthiness of such a closed node, this node will never interact with the other nodes, making it well protected, but completely isolated. Thus, a node should allow some of its information to be publicly accessible, building its trust toward facilitating interaction with others. Such information may include user pseudonym, potentially registered and used as a global, stable identifier (cf. the discussion in the previous section), geoloca- tion of the access device, connection details (e.g., bandwidth, bytes transmitted, and price per byte). Note, however, that propagation of such information in an ad-hoc network is always optional, and all the personal data protection regulations must be met. In addition, the more we would like to interact with others, the more open we should be to other devices. This would mean lower- ing the bar on privacy, but increasing the trust toward potential interlocutors, and vice versa. Although the issue of privacy and security is a complex one, in the context of ad-hoc networking, security may generally not be a big issue because of the typical harmless nature of activities in ad-hoc networking, such as news, discus- sion groups, alerts (e.g., extended car navigation system described later in this chapter), and so on. As far as privacy is concerned, each user decides what information he/she wishes to share publicly. It should be noted that most of our ordinary, everyday ad-hoc activities meet such relaxed requirements of privacy and security quite well, such as shopping assistance (except for the payment, which must always be realized in full-authorization mode*), on-the- road assistance, including alerts, tourist information, and so on. There are also some closed environments as well, where security is implied by some other external mechanisms, such as limitations in the physical access to the network. Some examples of such closed environments include, but not limited to, staff at a workplace being not accessible to the public, access devices with dedicated or registered networking unit, total encryption with PKI cer- tificates provided by dedicated authorization service, public places, such as museums with read-only information, and so on. 2.5. SECURITY AND PRIVACY IN MULTI-HOP NETWORKS As discussed previously, the problem of trade-off between security and privacy in ad-hoc networks becomes quite complex in multi-hop environment. The * There are some exceptions, for example, using anonymous e-money based on PKI encryption and some mathematical procedures, such as proofing with zero knowledge, and double encryption. However, such procedures are not in public and commercial use so far.
- 45. Security and Privacy in Multi-hop Networks 19 first question is when and how to determine that the mode of networking is going to be multi-hop. If this is so, who is going to determine (and how) the implications of this, the main implication being privacy and security? Second, who is at most threat in case of privacy and security breakdown? Is it the sender? Probably not. It is most likely the destination node or the correspond- ing nodes mediating in the traffic? Third, who is going to perform the security inspection? Finally, should the type of information being requested and/or its intended use determine the level of security? The question arises: is it necessary for the nodes (including source and destination) to be aware of whether they are connected in multi-hop mode? The case of transparency of the connectivity mode is akin to the Internet where the physical and MAC layer details are not consequential. However, there is one very important difference. In the fixed network, such as any local area network (LAN or Internet), the networking devices are placed at certain locations for longer periods of time, usually under the local control of a trusted administrator. So, not only is the network architecture stable, it is under the control and watchful eye of someone, be it based on some log analytics or information. As a result, if something undesirable happens, there is a possibility that the reason for this “something” will be uncovered, sooner or later. This is, however, not the case with ad-hoc and multi-hop networking, for many reasons. First, the network “configuration” may dynamically vary for a given source–destination pair. Second, not all the intermediate nodes may be authenticated (see previous discussion). Third, there is no guarantee that the traffic is not altered (or simply stopped) by a misbehaving intermediate node. For the reasons mentioned, in multi- hop ad-hoc networks, it may not be possible to determine the source of the problem. Now, going back to the second problem: who is most adversely impacted in case a multi-hop ad-hoc network (or a node) misbehaves? From the security perspective, there are two possible scenarios: • the information sent may be dangerous for a relay node or nodes; • the information sent may be dangerous for the receiving node, whereby the relay nodes function as a fence. Let us discuss the first case a little deeper. Consider for a moment that a virus is spreading across the network. As each intermediate relay node accepts the incoming traffic, it is possible that the virus would be detected and quarantined by the node, but it is harder to do because the traffic is not initiated by the node itself. In addition, if it does, it would mean the unnecessary overhead of processing and latency in the node. From a legal perspective, it is difficult to find and prosecute the offending node unless each and every packet is tagged by the node it passes through. It would seem like a good preventive measure for each and every relay (intermediate) node to inspect the incoming traffic for any viruses or illegal tampering.
- 46. 20 Architectural Requirements Examining the information passing through a node raises an important issue of intrusion of privacy. The intervening node may listen to the commu- nication or introduce dangerous information. Applying the idea of VPN and completely encrypting the traffic seems to be the only good solution. Since there is no perfect solution to balancing privacy and security, it should be left to the sender and receiver to negotiate and agree what trade-off is acceptable to them. So, if on one hand, full inspection is the basic security requirement while, on the other hand, no inspection at all is the basic privacy requirement, how is reasonable trade-off provided? Unfortunately, there is no one single answer to this problem. The more the corresponding part secures itself, the less it is trusted by the relay nodes and thus there is a greater chance to reject a relay request. So, the trade-off should be the individual choice, depending on a sender, a receiver, and relay(s) security policy(ies)—no single approach exists, only negotiations are possible or the optimistic approach may be applied (let us try and see what happens). 2.6. FILTERING THE TRAFFIC IN AD-HOC NETWORKING AND MULTI-HOP RELAYING Being active in an ad-hoc or multi-hop network means accepting incoming messages, generating own traffic, or acting as a relay. All these activities are based on taking decisions what to accept (send or resend) and what to block. In short, filtering means doing something with the incoming, outcoming, and transiting* traffic. A question arises: is filtering really necessary? The answer is yes, for at least two reasons. First, proper filtering may substantially improve local security, for example, by blocking network messages infested with viruses or similar dangerous content. Second, networking activities always consume station resources—computational power, network bandwidth, and most importantly, in mobile stations, energy in batteries. Let us now discuss these two filtering reasons in more detail. First, consider filtering for local security protection. Dangerous traffic to be filtered out may be generated as (1) the traffic addressed to a particular station, and/or (2) the traffic broadcasted to everybody.Usually,in a stationary network, the traffic of the second type is used to detect some easy-to-attack network nodes, followed by an individual attack of the first type. Fortunately, in ad-hoc and especially multi-hop networking, a particular station is extremely hard to be addressed in a stable manner, due to continuous network re-configuration * Speaking more generally, the filtering is related not only with sending or stopping some mes- sages.A relay station may also delay some messages and change the contents, place of origin and/ or destination, and so on. However, to clarify the text, we assume that filtering is mostly related with a decision whether to accept or reject given network traffic.
- 47. Filtering the Traffic 21 and frequent changes of connections.* Therefore, we would rather discuss potential impact of the second type of dangerous traffic. Classical examples of such traffic include viruses and malware. To detect such damaging traffic, one should carefully inspect the contents of all incoming and transiting network messages. However, as it was discussed in the previous section, such inspection intrudes into privacy. On the other hand, if some traffic cannot be decrypted and analyzed by a relay node, such traffic is not a danger for this node. One may expect that majority of the users will relay uninspected traffic even if such traffic is a potential security and privacy threat. Thus, the security and privacy concerns will not be the primary reasons to block some network activities. Second, let us analyze the filtering related with local-resource consumption. We must realize that each network transmission, notwithstanding whether it is initiated locally or transited as a relay traffic, consumes some local resources: computational power of a processor, memory, network bandwidth, and, last but not the least, the energy needed for the node to function. Thus, the more a station is active in networking, the less are its resources available to perform other functions. In the extreme case of multi-hop networking, most of the resources are consumed in relaying traffic, and very little is left for its own functions. On the other hand, if a station blocks all the traffic, it would be disconnected from the other stations. Therefore, it is apparent that a proper balance is needed that is individualized to each node. So, what is the best strategy for achieving an optimum balance? If we would like to determine such a strategy, we must base the filtering decisions on some additional information about the incoming or transiting traffic. As it was said before, it is hard to assume that the message contents will be unencrypted and fully accessible for the relay nodes, mainly due to privacy protection reasons. Therefore, these decisions should be based on some additional information, such as the addresses of the origin and the destination nodes. For ad-hoc net- working involving two directly connected nodes, this is not a problem, unless anonymity/pseudonymity must be maintained. For multi-hop networking, however, this is much more complex. First, the knowledge of the origin and the destination of the given information depends on the routing strategy, although sometimes the address of the preceding and the following node is known but not the whole route. Thus, a decision to relay (or not to relay) a message is sometimes based on partial (i.e., incomplete) information. Second, the network configuration is sometimes so dynamic that different parts of a message are passed by different nodes on different routes. Third, not all network nodes are honest with each other. However, the previous history of * In the mobile networking environment, recently, some methods of attacks toward particular stations were identified even in highly reconfigurable networks, for example, “false base station” attack observed in GSM networks, or GPS (GPS, 2012) jammers (Jammers, 2012) based on ground imitations of navigational satellites. However, these problems are out of the scope of this book— for ad-hoc and multi-hop networking, we do not need stable and fully addressable network nodes to be attacked or falsified, such as the base stations and satellites.
- 48. 22 Architectural Requirements trust and honesty of the known nodes can be exploited by developing appro- priate techniques. There are many approaches to filtering traffic locally, whether incoming or transiting. • The relay node knows the complete route of the message, including the origin and the destination addresses. The node can decide on the extent of filtering based on the prior knowledge of the trustworthiness of the nodes. If it is above a certain predefined threshold, the message can simply be relayed. • The relay node has only the partial knowledge of the route of the message, (e.g., the address of the preceding and the following nodes). In such a scenario, the relay node can decide how deep the filtering should be done based on some additional information. The question of how to compute and store the trustworthiness of the nodes involved in the transmission remains to be addressed. One method is to rank the trustworthiness, but it is rather complex to do.There are many reasons for this. First, if one of the relay nodes is selfish, it can stop the whole traffic. Unfortunately, it is difficult to identify such a node because there is no way to differentiate if the nonarrival of the packets at the destination node is due to the blocking or some transmission error (e.g., congestion and poor quality of radio signal). One solution could be by requesting acknowledgment at every hop, but this would mean significant overhead (affecting radio layer effi- ciency), in addition to these other difficulties: (1) nonguarantee of the delivery of the acknowledge message, and (2) the fact that a selfish station may simply send an acknowledgement message but not relay the message itself.Therefore, if the transfer fails, the only approach may be to punish all the nodes involved in the transmission by lowering their trustworthiness. Second, sometimes, the origin node does not necessary know in advance the addresses of all the relay nodes. If a message transfer is somewhere broken, it is not possible to deter- mine the last node where the transmission stopped. Therefore, it becomes difficult to pinpoint which node to punish. Sometimes, the misbehaving node may continuously change its identifier, which would make it even more diffi- cult to identify the culprit node. Regarding where to store the information about trustworthiness, there are two possible solutions: (1) each node keeps a record of its own honesty, using own resources, and (2) a central repository (server) in the network maintains a record of trustworthiness of all the nodes and ranks them, making the data- base available to anyone as a global service. Let us discuss the first solution in more detail. In ad-hoc networking, the cooperation among nodes happens locally; however, the “local” neighborhood is usually highly dynamic. In extreme cases, a node is going to cooperate with a given node only once while relying on other nodes in the neighborhood to extend connectivity. As a result, from the perspective of this node, computing
- 49. QoS 23 trustworthiness for such incidental cooperation makes little sense. Moreover, the trustworthiness information is useful only in the future, but it is difficult to predict when it would actually be used. Regarding the second solution, a statistical trustworthiness ranking of every node in the network is an attractive solution. However, there are several dis- advantages in such an approach. First, a centralized service is needed, in addi- tion to previously mentioned identification and authentication service. Second, we risk a situation where each nomadic node would perhaps get punished because of its mobility, resulting in sometimes not being able to connect reli- ably. Third, as the ad-hoc network traffic is usually very fragile, transmission errors could make the nodes at network boundaries unreachable. Finally, it is very easy to cheat in such a service, for example, sending falsified rankings about nodes that one never cooperated with. While it would be hard to determine and to keep the trustfulness informa- tion about the nodes, one may expect that a majority of the users would risk the selfish behavior, counting on the fact that such behavior would be practi- cally undetectable by the others. However, if a critical mass of such users is reached,the network would become practically unusable—no multi-hop relay- ing would be possible, and no ad-hoc cooperation would be established. Please also note that fair nodes are somehow always punished, by fast con- sumption of their resources,mainly the battery energy.Thus,it may be expected that a fair node would hardly survive in ad-hoc network, again leading the whole network to a dead state. The previous discussion leads us to conclude that filtering, although attrac- tive, has problems of its own. 2.7. QoS In the previous sections, we discussed problems related with security, privacy, and trust management in ad-hoc and multi-hop networks,Another issue worth discussing is that of quality of service (QoS) (QoS, 1994/2008/2011). Can we trust the network, and if so, can we expect a certain level of quality in ad-hoc and multi-hop networking? The answer for both is, unfortunately, not. We already discussed the issue of trustability in the previous sections, so we will repeat it here. Regarding QoS, the overall configuration of the network may be very dynamic—there are frequent transmission errors due to frequent disconnections and reconnections, incidental routing, incidental interference in the information content, and so on. Interestingly, some applications do not call for a high degree of trustability and QoS, for example, looking for road information, timetable for a bus, and local support for everyday shopping.A well-known and widely applied ad-hoc approach “if something is wrong, try once again” may be quite successful— “once again” will probably mean “completely different environment and network neighborhood, maybe more friendly users.”
- 50. 24 Architectural Requirements 2.8. ADDRESSABILITY Networking means exchanging information with other users, that is, access devices of these users.And ad-hoc networking means exchanging information with devices selected in an ad-hoc manner.A question arises: how do we select a given device? How do we communicate with someone in ad-hoc manner? And what does choosing someone “ad-hoc” mean? Could it be any user/device within the range? Ideally speaking, the answer is yes. But, in practice, other constraints need to be satisfied, for example, trust, privacy, security, willingness to share, and energy consumption. Even if we are able to select “someone,” such ad-hoc “someone” tends to be anonymous, hiding his/her identification details. Maybe that is not the case for a service provider, for example, a restaurant, a taxi company, except for examples such as finding a player to play chess with and asking for help form an anonymous neighbor (e.g., “do you know any good restaurant nearby?”). Broadcasting only partially reduces this problem, but we rarely want to com- municate with everybody in the neighborhood, because in many instances “everybody” means “nobody.” In fact, for ad-hoc cooperation, we usually locate a specific person to be “someone.” For example, we do not stay on the road and shout “does anybody know the way to . . .”? Instead, we select a single person and ask him/her individually. Thus, in ad-hoc networking and ad-hoc cooperation with ad-hoc interlocutors, we must address the issue of “anonymous addressing.” Before finding a solution for this problem, let us first analyze how this problem has been solved in other networks. In a typical computer network, with stable nodes and network connections, the users are usually mapped to selected nodes. For example, if we would like to send an e-mail to someone, we have to know the (1) exact address of the node with mailbox of this “someone,” and the (2) exact name of “someone,” which is usually valid only locally within the just-addressed network node. We are not able to send an e-mail to “anyone” or “everybody,” even in the domain of a single computer or a local area network. Thus, in a classical network, we observe no anonymity in addressing. In a typical mobile telecommunication (cellular) network, the problem is somewhat easier to solve. Although a mobile user is not tied to a single network node, he/she is always tracked to find the node to which (i.e., a base station) he/she is connected at the moment. Let us ask the question: is anonymous addressing possible in such a network? Unfortunately not; instead, each user is deterministically and globally identified by a phone number, and this number (more precisely, a device linked with this number by a SIM card) is registered in each node before he/she can be called by others. Therefore, an address of a device is composed of a variable identifier of a network node that the device is currently connected to and its unique device number. How is then addressing handled in ad-hoc and multi-hop networks? Is the position of a node (i.e., an access device belonging to a user) stable, and is there a unique identifier for this node registered anywhere
- 51. Addressability 25 and globally used? The answer to the first question is “definitely not,” and for the latter “not necessarily.” Therefore, the approaches to addressing in classical networks are not directly applicable to multi-hop and ad-hoc networks. However, there are heuristic solutions that are possible. First, we may have to give up the idea of ad-hoc identification of any node, and require that communication will be allowed only with well-addressable, nonanonymous nodes. Here, one interlocutor, that is, a destination of a communication link, is stable and well known, while the initiator at the other end of the link may remain anonymous, except for low-level technical information needed for return routing. This would be the case for public service providers, such as restaurants, taxis, hotels, shops. Second, those who want to be addressable may register their identifiers (usually pseudonyms or even neural technical numbers, such as device MAC address or International Mobile Equipment Identity [IMEI] [IMEI, 2010] number) somewhere in the network in a public, centralized database. These identifiers must be accompanied with some parameters useful for contextual selection of the device among other devices. For example, these parameters may describe some skills and capabilities of the device owner (e.g., “I am able to play chess.”), and some dynamic values, such as the current geoposition of the device. Third, we may assume that every anonymous message, that is, a request for “anyone,” is broadcasted to everyone in the local neighborhood (to any device capable of receiving such message). We assume that at any time, the number of devices within the range is reasonably small. Usually, the communication is one-way as the initiator does not expect that many users would respond. This could also mean resending the message to devices beyond the immediate neighborhood in a multi-hop mode. Some real-life applications of such systems fall within the domain of public security (e.g., traffic alert system—“traffic jam behind” and “danger, escape quickly”). In the first and the third examples earlier, the receiver is (somehow) well- known and thus fully addressable to the sender. However, that is not the case in the second example.To select a single device from a set of possible devices- in-range, we may use only the set of description parameters stored in the database. So, we have to provide a binding mechanism using a mapping pro- cedure for a set of parameter values to an identifier (a pseudonym) of a single device, which is “the best.” There are at least two problems in such a binding approach. First, the set of actual parameter values may be incomplete, that is, not all the parameters may be updated with current and correct values. For example, we do not necessarily know the real name of the device owner. Second, some descriptor values could be fuzzy and incomplete. For example, we may want to address a device “in the neighborhood,” but the neighborhood is not defined in terms of the exact distance in meters! Some of these fuzzy searching problems have been already discussed in the area of geographic systems and databases, as well navigation-support systems and personal devices. However, not all choices can be quantified for all situations and for everyone.
- 52. 26 Architectural Requirements As discussed in the earlier examples, additional information about a device (and indirectly the device owner or device carrier),constituting a set of descrip- tion parameters, may be either: • fixed (e.g., car model, its color, license plate number, and user photo), or • dynamic (e.g., current geolocation, its state, and pending activity). The fixed part is usually declared once and then very rarely updated after- wards. In contrast to the fixed part, the dynamic part is updated periodically. The updates of the dynamic parameter values should be provided automati- cally if possible, while the fixed parameter values should be provided through human interaction or by means of stationary devices or traditional networking approaches. To be useful, the present-day addressing approaches need to be substan- tially extended. In multi-hop ad-hoc networks, the fuzzy addressing should use personalized mapping of descriptions of devices to their actual identifiers and addresses. Figure 2.2 presents a sample extension of addressing methods in the context of a classical Transmission Control Protocol/Internet Protocol (TCP/IP) network (TCP/IP, 2012). Nowadays, applications utilize DNS names of network nodes that are mapped by specialized DNS servers to physical node addresses (IP number). Users are neither aware nor need to use IP addresses to reach the destination. If a DNS server is down, it would mean, from the user’s perspective, that the whole network is down and nobody is reachable. Now imagine that there is an additional software layer called “Mapping” between the applications and the DNS service. Such “extended DNS” (eDNS for short) service would perform a selection based on actual values of a node description. A mode of typical usage of eDNS service is as follows: • A device is registered in a database, at device owner’s request. Such a database or a directory may be either public (and thus shared by every- body) or local (private), to serve for limited domain (e.g., a restricted geo-area such as a single city). For privacy protection, some access privi- leges may be granted, for example, regular class, premium class, emer- gency class (e.g., homeland security, fire, medical). Figure 2.2. Evolution from classical to fuzzy and contextual addressing.
- 53. Addressability 27 • A user (with certain privileges) may request the database for either: s a detailed description of the current state of a device, on condition that the unique identifier of this device is given as an input parameter, or s a set of identifiers of the devices fulfilling certain criteria, to be verified by means of the current values of the description parameters. As for the first case, this is similar to the classical addressing mechanism, and may be used for classical searching and accessing the well-known fixed network nodes (cf. the previously presented application area with fixed services, such as restaurants, ATM [automated teller machine]* locations, etc.). The second case is much more interesting, but much more complex. Even if some parameter values are quite stable (such as the name of a device owner, a color and license plate number of his/her car, real address, etc.), there are also some values that may vary (such as the geoposition of the access device). Thus, classical addressing cannot be applied. Instead, we need a declarative query language rather than fixed DNS addresses. A computed result of such a query would have the same meaning as a DNS/IP address, or a set of addresses for a multicast communication. We propose the approach of eDNS query language,† which is a loose adap- tation of the well-known SQL query language (SQL, 2012). We provide more details of the eDNS in the following: select driver from my_current_position + 1 mile where licence plate like NY123*; select license_plate from highway_51 where speed>55mph; Note that the proposed query language must use a fixed set of parameters (not necessarily domain names), which is similar to the original SQL language that uses existing relational database. Thus, in order to compute the queries, one must include in the description such parameters as current geoposition (both of the query sender and all the other cars involved), current speed, license plate numbers of the cars, highway identifiers, and so on. Going further, we may propose a fuzzy query language, enabling a descrip- tion of the destination device in the form of a semi-natural-language text, for example (taking inspiration from the telematics context): „To the yellow Ford Transit just passing me by” „To Ferrari No NY1234” „To the pretty girl in a funny car just after my car” † Note that this is not a proposal for a new declarative language—this is rather an indication how we could improve anonymous and fuzzy addressing in ad-hoc and multi-hop networks. * A note for EU citizens: we also call these places a “cash machine” or a “dispenser.”
- 54. 28 Architectural Requirements As it may be seen, with such a fuzzy query language, we perform a mapping from fuzzy user-defined description of a target to a dynamic location of this target (its current address, not necessarily stable). Going still further, we may propose fuzzy and group addressing instead of a single receiving device. Such addressing may be used for local multicasting and even broadcasting, in two basic modes: • To all devices fulfilling certain criteria (usually expecting no answer).This mode may be used, for example, for broadcasting local security alert. • To any device from a set of devices fulfilling certain criteria (expecting at least one answer). Some (self-explained) examples of the fuzzy group addressing are provided: „An accident crossing 3rd East and 45th North, road closed, traffic jam” „Does anyone know a location of a good restaurant nearby?” 2.9. SEARCHABILITY The fuzzy and group addressing described in the previous section leads to a generic searching mechanism, where we provide a searching query, specifying some criteria to select a set of addresses of given devices that are ad-hoc con- nected with the network. Note that such searching may be based on a descrip- tion of the device capabilities, current state, user (i.e., device owner) or device carrier characteristics, and so on. So, a question arises if a classical searching scenario, such as Google-like queries based on keywords (Google, 2012), is enough. To answer this question, we have to analyze more deeply the main purpose of ad-hoc searching. First, are we looking for some information, or maybe information change? In Google search, obviously we are looking for some information. If we would like to detect a change in the given information, we have to periodically monitor this information and compare its value with the previous one. We also should analyze the real meaning of this change, as some changes are meaningful (i.e., dynamic advertisement on a monitored web page) and some are not. In contrast, while we try to detect changes in information in the ad-hoc mode, possibly in multi-hop networking, we find that periodic comparison of information is very hard to achieve. This is for several reasons. First, the infor- mation source is probably also connected in ad-hoc mode, resulting in frequent changes not only in information, but also the way the information is to be accessed. Second, multi-hop networking may introduce several distortions to the monitoring process, as the behavior of such networks is unpredictable.And
- 55. Another Random Document on Scribd Without Any Related Topics
- 56. 12.3. Re. 2.3; to labour under disease, be sick, Ja. 5.15. 73: Κἀμοί, (καὶ ἐμοί) see κἀγώ. 74: Κάμπτω, f. ψω, a.1. ἔκαμψα, trans. to bend, inflect, the knee, Ro. 11.4. Ep. 3.14; intrans. to bend, bow, Ro. 14.11. Phi. 2.10. 75: Κἄν, (by crasis καὶ ἐάν) and if, Mar. 16.18; also if, Mat. 21.21; even if, if even, although, Jno. 10.38; if so much as, He. 12.20; also in N.T., simply equivalent to καί as a particle of emphasis, by a pleonasm of ἄν, at least, at all events, Mar. 6.56. Ac. 5.15. 2 Co. 11.16. 76: Κανανίτης, ου, ὁ, (Aram. קנאן, fr. Heb. קנא, to be zealous) Canaanite, i.q. ζηλωτής, zealot, Mat. 10.4. Mar. 3.18; coll. Lu. 6.15, & Ac. 1.13. 77: Κανών, ονος, ὁ, (κάννα v. κάνη, a cane) a measure, rule; in N.T., prescribed range of action or duty, 2 Co. 10.13, 15, 16; met. rule of conduct or doctrine, Ga. 6.16. Phil. 3.16. 78: Καπηλεύω, f. εύσω, (pr. to be κάπηλος, a retailer, huckster; and, as these persons had the reputation of increasing their profits by adulteration, hence,) in N.T., to corrupt, adulterate, 2 Co. 2.17. 79: Καπνός, οῦ, ὁ, smoke, Ac. 2.19. Re. 8.4, et al. 80: Καρδία, ας, ἡ, (κέαρ, idem)
- 57. 93 the heart; the heart, regarded as the seat of feelings, impulse, affection, desire, Mat. 6.21; 22.37. Phil. 1.7, et al.; the heart, as the seat of intellect, Mat. 13.15. Ro. 1.21, et al.; the heart, as the inner and mental frame, Mat. 5.8. Lu. 16.15. 1 Pe. 3.4, et al.; the conscience, 1 Jno. 3.20, 21; the heart, the inner part, middle, centre, Mat. 12.40, et al. 81: Καρδιογνώστης, ου, ὁ, (καρδία & γινώσκω) heart-knower, searcher of hearts, Ac. 1.24; 15.8. N.T. 82: Καρπός, οῦ, ὁ, fruit, Mat. 3.10; 21.19, 34; fr. the Heb. καρπὸς κοιλίας, fruit of the womb, offspring, Lu. 1.42; καρπὸς ὀσφύος, fruit of the loins, offspring, posterity, Ac. 2.30; καρπὸς χειλέων, fruit of the lips, praise, He. 13.15; met. conduct, actions, Mat. 3.8; 7.16. Ro. 6.22; benefit, profit, emolument, Ro. 1.13; 6.21; reward, Phi. 4.17, et al. 83: Καρποφορέω, ῶ, (καρπός & φορέω, fr. φέρω f. ήσω, a.1. ἐκαρποφόρησα, to bear fruit, yield, Mar. 4.28; met. to bring forth or exhibit actions or conduct, Mat. 13.23. Ro. 7.5; mid. to expand by fruitfulness, to develop itself by success, Col. 1.6. 84: Καρποφόρος, ου, ὁ, ἡ, (fr. same) fruitful, adapted to bring forth fruit, Ac. 14.17. 85: Καρτερέω, ῶ, (καρτερός, by metath. fr. κράτος) f. ήσω, a.1. ἐκαρτέρησα, to be stout; to endure patiently, bear up with fortitude, He. 11.27. 86: Κάρφος, εος, τό, (κάρφω, to shrivel)
- 58. any small dry thing, as chaff, stubble, splinter, mote, &c.; Mat. 7.3, 4.5. Lu. 6.41, 42. 87: Κατά, prep., with a genitive, down from, adown, Mat. 8.32; down upon, upon, Mar. 14.3. Ac. 27.14; down into; κατὰ βάθους, profound, deepest, 2 Co. 8.2; down over, throughout a space, Lu. 4.14; 23.5; concerning, in cases of pointed allegation, 1 Co. 15.15; against, Mat. 12.30, et al.; by, in oaths, Mat. 26.63, at al.; with an accusative, of place, in the quarter of; about, near, at, Lu. 10.32. Ac. 2.10; throughout, Lu. 8.39; in, Ro. 16.5; among, Ac. 21.21; in the presence of, Lu. 2.31; in the direction of, towards, Ac. 8.26. Phi. 3.14; of time, within the range of; during, in the course of, at, about, Ac. 21.1; 27.27; distributively, κατ' οἶκον, by houses, from house to house, Ac. 2.46; κατὰ δύο, two and two, 1 Co. 14.27; καθ' ἡμέραν, daily, Mat. 26.55, et al.; trop., according to, conformably to, in proportion to, Mat. 9.29; 25.15; after the fashion or likeness of, He. 5.6; in virtue of, Mat. 19.3; as respects, Ro. 1.3. Ac. 25.14. He. 9.9. 88: καταβαίνω, (κατά & βαίνω) f. βήσομαι, a.2. κατέβην, imperat. κατάβηθι, & κατάβα, p. καταβέβηκα, to come or go down, descend, Mat. 8.1; 17.9; to lead down, Ac. 8.26; to come down, fall, Mat. 7.25, 27, et al.; to be let down, Ac. 10.11; 11.5. 89: Καταβάλλω, (κατά & βάλλω) f. βαλῶ,
- 59. to cast down, Re. 12.10; to prostrate, 2 Co. 4.9; mid. to lay down, lay as foundation, He. 6.1. 90: Καταβαρέω, ῶ, (κατά & βαρέω) f. ήσω, pr. to weigh down; met. to burden, be burdensome to, 2 Co. 12.16. L.G. 91: Καταβαρύνω, (κατά & βαρύνω) f. υνῶ, to weigh down, oppress; pass. to be weighted down by sleep, by drowsy, v.r. Mar. 14.40. 92: Κατάβᾰσις, εως, ἡ, (καταβαίνω) the act of descending; a way down, descent, Lu. 19.37. 93: Καταβιβάζω, (κατά & βιβάζω) f. άσω, to cause to descend, bring or thrust down, Mat. 11.23. Lu. 10.15. 94: Καταβολή, ῆς, ἡ, (καταβάλλω) pr. a casting down; laying the foundation, foundation; beginning, commencement, Mat. 13.35; 25.34, et al.; conception in the womb, He. 11.11. 95: Καταβραβεύω, (κατά & βραβεύω) f. εύσω, pr. to give an unfavourable decision as respects a prize, to disappoint of the palm; hence, to beguile of, cause to miss, Col. 2.18. 96: Καταγγελεύς, έως, ὁ, one who announces any thing, a proclaimer, publisher, Ac. 17.18: equivalent to κατάγγελος. N.T. 97: Καταγγέλλω, (κατά & ἀγγέλλω) f. γελῶ, a.2. κατηγγέλην,
- 60. 94 to announce, proclaim, Ac. 13.38; in N.T., to laud, celebrate, Ro. 1.8. 1 Co. 11.26; to set forth, teach, inculcate, preach, Ac. 4.2; 13.5, et al. 98: Καταγελάω, ῶ, (κατά & γελάω) f. άσω, άσομαι, to deride, jeer, Mat. 9.24. Mar. 5.40. Lu. 8.53. 99: Καταγινώσκω, (κατά & γινώσκω) f. γνώσομαι, to determine against, condemn, blame, reprehend, Ga. 2.11. 1 Jno. 3.20, 21. 100: Κατάγνυμι, v. -ύω, (κατά & ἄγνυμι, to break) f. κατάξω, & κατεάξω, a.1. κατέαξα, a.2. pass. κατεάγην (ᾱ), subj. κατεαγῶ, to break in pieces, crush, break in two, Mat. 12.20. Jno. 19.31, 32, 33. 101: Κατάγω, (κατά & ἄγω) f. ξω, a.2. κατήγαγον, to lead, bring, or conduct down, Ac. 9.30; 22.30; 23.15, 20, 28; to bring a ship to land; pass. κατάγομαι, a.1. κατήχθην, to come to land, land, touch, Lu. 5.11, et al. 102: Καταγωνίζομαι, (κατά & ἀγωνίζομαι) f. ίσομαι a.1 κατηγωνισάμην, to subdue, vanquish, conquer, He. 11.33. L.G. 103: Καταδέω, (κατά & δέω) f. ήσω, to bind down; to bandage a wound, Lu. 10.34. 104: Κατάδηλος, ου, ὁ, ἡ, τό, -ον, (κατά & δῆλος) quite manifest or evident, He. 7.15. 105: Καταδικάζω, (κατά & δικάζω) f. άσω, to give judgement against, condemn, Mat. 12.7, 37. Lu. 6.37. Ja. 5.6.
- 61. 106: Καταδίκη, ης, ἡ, (κατά & δίκη) condemnation, sentence of condemnation, v.r. Ac. 25.15. 107: Καταδιώκω, (κατά & διώκω) f. ξω, to follow hard upon; to track, follow perseveringly, Mar. 1.36. 108: Καταδουλόω, ῶ (κατά & δουλόω) f. ώσω, to reduce to absolute servitude, make a slave of, 2 Co. 11.20. 109: Καταδυναστεύω, (κατά & δυναστεύω, to rule, reign) f. εύσω, to tyrannise over, oppress, Ac. 10.38. Ja. 2.6. 110: Κατάθεμα, ατος, τό, (κατατίθημι) an execration, curse, by meton. what is worthy of execration, i.q. κατανάθεμα, v.r. Re. 22.3: (N.T.) whence 111: Καταθεματίζω, f. ίσω, to curse, v.r. Mat. 26.74. N.T. 112: Καταισχύνω, (κατά & αἰσχύνω) f. υνῶ, to shame, put to shame, put to the blush, 1 Co. 1.27; pass. to be ashamed, be put to the blush, Lu. 13.17; to dishonour, disgrace, 1 Co. 11.4, 5; fr. the Heb. to frustrate, disappoint, Ro. 5.5; 9.33. 113: Κατακαίω, (κατά & καίω) f. καύσω, a.2. pass. κατεκάην, to burn up, consume with fire, Mat. 3.12; 13.30, 40, et al. 114: Κατακαλύπτομαι, (mid of κατακαλύπτω, to veil, fr. κατά & καλύπτω)
- 62. to veil one's self, to be veiled or covered, 1 Co. 11.6, 7.) 115: Κατακαυχάομαι, ῶμαι,(κατά & καυχάομαι) f. ήσομαι, to vaunt one's self against, to glory over, to assume superiority over, Ro. 11.18. Ja. 2.13; 3.14. S. 116: Κατάκειμαι, (κατά & κεῖμαι) f. είσομαι, to lie, be in a recumbent posture, be laid down, Mar. 1.30; 2.4; to recline at table, Mar. 2.15; 14.3, et al. 117: Κατακλάω, ῶ, (κατά & κλάω) f. άσω, a.1. κατέκλᾰσα, to break, break in pieces, Mar. 6.41. Lu. 9.16. 118: Κατακλείω, (κατά & κλείω) f. είσω, to close, shut fast; to shut up, confine, Lu. 3.20. Ac. 26.10. 119: Κατακληροδοτέω, ῶ, (κατά, κλῆρος, & δίδωμι f. ήσω, to divide out by lot, distribute by lot, Ac. 13.19. S. 120: Κατακληρονομέω, ῶ, (κατά, κλῆρος, & νέμω, to distribute) same a preceding, for which it is a v.r. 121: Κατακλίνω, (ῑ), (κατά & κλίνω) f. ινῶ, a.1. κατέκλῑνα, a.1. pass. κατεκλίθην (ῐ), to cause to lie down, cause to recline at table, Lu. 9.14; mid. to lie down, recline, Lu. 14.8; 24.30. 122: Κατακλύζω, (κατά & κλύζω, to lave, wash) f. ύσω, a.1. pass. κατεκλύσθην, to inundate, deluge, 2 Pe. 3.6: whence 123: Κατακλυσμός, οῦ, ὁ,
- 63. 95 an inundation, deluge, Mat. 24.38, 39, et al. 124: Κατακολουθέω, ῶ (κατά & ἀκολουθέω) f. ήσω, to follow closely or earnestly, Lu. 23.55. Ac. 16.17 125: Κατακόπτω, (κατά & κόπτω) f. ψω, to cut or dash in pieces; to mangle, wound, Mar. 5.5. 126: Κατακρημνίζω, (κατά & κρημνός, a precipice) f. ίσω, to cast down headlong, precipitate, Lu. 4.29. 127: Κατάκρῐμα, ατος, τό, condemnation, condemnatory sentence, Ro. 5.16, 18; 8.1: (L.G.) from 128: Κατακρίνω, (ῑ), (κατά & κρίνω) f. ινῶ, a.1. κατέκρῑνα, p. pass. κατακέκρῐμαι, a.1. pass. κατεκρίθην (ῐ), to give judgment against, condemn, Mat. 27.3 Jno. 8.10, 11, et al.; to condemn, to place in a guilty light by contrast, Mat. 12.41, 42. Lu. 11.31, 32. He. 11.7: whence 129: Κατάκρῐσις, εως, ἡ, condemnation, 2 Co. 3.9; censure, 2 Co. 7.3. S. 130: Κατακυριεύω, (κατά & κυριεύω) f. εύσω, to get into one's power; in N.T., to bring under, master, overcome, Ac. 19.16; to domineer over, Mat. 20.25, et al. L.G. 131: Καταλᾰλέω, ῶ, (κατά & λαλέω) f. ήσω, to blab out; to speak against, calumniate, Ja. 4.11. 1 Pe. 2.12; 3.16: whence 132: Καταλαλία, ας, ἡ
- 64. evil-speaking, detraction, backbiting, calumny, 2 Co. 12.20. 1 Pe. 2.1. S. 133: Κατάλᾰλος, ου, ὁ, ἡ, slanderous, a detractor, calumniator, Ro. 1.30. N.T. 134: Καταλαμβάνω, (κατά & λαμβάνω) f. λύψομαι, a.2. κατέλᾰβον, to lay hold of, grasp; to obtain, attain, Ro. 9.30. 1 Co. 9.24; to seize, take possesssion of, Mar. 9.18; to come suddenly upon, overtake, surprise, Jno. 12.35; to deprehend, detect in the act, seize, Jno. 8.3, 4; met. to comprehend, apprehend, Jno. 1.5; mid. to understand, perceive, Ac. 4.13; 10.34, et al. 135: Καταλέγω, (κατά & λέγω) f. ξω, to select; to reckon in a number, enter in a list or catalogue, enrol. 1 Ti. 5.9. 136: Κατάλειμμα, ατος, τό, a remnant, a small residue, Ro. 9.27: (L.G.)from 137: Καταλείπω, (κατά & λείπω) f. ψω, a.2 κατέλῐπον, to leave behind; to leave behind at death, Mar. 12.19; to relinquish, let remain, Mar. 14.52; to quit, depart from, forsake, Mat. 4.13; 16.4; to neglect, Ac. 6.2; to leave alone, or without assistance, Lu. 10.40; to reserve, Ro. 11.4. 138: Καταλιθάζω, (κατά & λιθάζω) f. άσω, to stone, kill by stoning, Lu. 20.6. S. 139: Καταλλᾰγή, ῆς, ἡ, pr. an exchange; reconciliation, restoration to favour, Ro. 5.11; 11.15. 2 Co. 5.18, 19: from 140: Καταλλάσσω, (κατά & ἀλλάσσω)
- 65. f. άξω, a.2. pass. κατηλλάγην (ᾰ), to change, exchange; to reconcile; pass. to be reconciled, Ro. 5.10. 1 Co. 7.11. 2 Co. 5.18-20. 141: Κατάλοιπος, ου, ὁ, ἡ, (καταλείπω) remaining; οἱ κατάλοιποι, the rest, Ac. 15.17. 142: Κατάλῠμα, ατος, τό, a lodging, inn, khan, Lu. 2.7; a guest- chamber, cœnaculum, Mar. 14.14. Lu. 22.11: (L.G.) from 143: Καταλύω (ῡ), (κατά & λύω) f. ύσω, a.1. pass. κατελύθην (ῠ), to dissolve; to destroy, demolish, overthrow, throw down, Mat. 24.2; 26.61; met. to nullify, abrogate, Mat. 5.17. Ac. 5.38, 39, et al.; intrans. to unloose harness, &c., to halt, to stop for the night, lodge, Lu. 9.12. 144: Καταμανθάνω, (κατά & μανθάνω) f. μαθήσομαι, a.2. κατέμᾰθον, to learn or observe thoroughly; to consider accurately and diligently, contemplate, mark, Mat. 6.28. 145: Καταμαρτῠρέω, ῶ, (κατά & μαρτυρέω) f. ήσω, to witness or testify against, Mat. 26.62; 27.13, et al. 146: Καταμένω, (κατά & μένω) f. ενῶ, to remain; to abide, dwell, Ac. 1.13. 147: Καταμόνας, (κατά & μόνος) alone, apart, in private, Mar. 4.10. Lu. 9.18. 148: Κατανάθεμα, ατος, τό, (κατά & ἀνάθεμα) a curse, execration; meton. one accursed, execrable, Re. 22.3: (N.T.) whence 149: Καταναθεματίζω, f. ίσω,
- 66. 96 to curse, Mat. 26.74. N.T. 150: Κατανᾱλίσκω, (κατά & ἀναλίσκω) f. λώσω, to consume, as fire, He. 12.29. 151: Καταναρκάω, ῶ,(κατά & ναρκάω, to grow torpid) f. ήσω, in N.T., to be torpid to the disadvantage of any one, to be a dead weight upon; by impl. to be troublesome, burdensome to, in respect of maintenance, 2 Co. 11.9; 12.13, 14. 152: Κατανεύω, (κατά & νεύω) f. εύσομαι, pr. to nod, signify assent by a nod; genr. to make signs, beckon, Lu. 5.7. 153: Κατανοέω, ῶ (κατά & νοέω) f. ήσω, to perceive, understand, apprehend, Lu. 20.23; to observe, mark, contemplate, Lu. 12.24, 27; to discern, descry, Mat. 7.3; to have regard to, make account of, Ro. 4.19. 154: Καταντάω, ῶ, (κατά & ἀντάω) f. ήσω, to come to, arrive at, Ac. 16.1; 20.15; of an epoch, to come upon, 1 Co. 10.11; met. to reach, attain to, Ac. 26.7, et al. L.G. 155: Κατάνυξις, εως, ἡ, in N.T., deep sleep, stupor, dulness, Ro. 11.8. S. 156: Κατανύσσω, (κατά & νύσσω) f. ξω, a.2. pass. κατενύγην, to pierce through; to pierce with compunction and pain of heart, Ac. 2.37. 157: Καταξιόω, ῶ (κατά & ἀξιόω) f. ώσω,
- 67. to account worthy of, Lu. 20.35; 21.36. Ac. 5.41. 2 Th. 1.5. 158: Καταπᾰτέω, ῶ, (κατά & πατέω) f. ήσω, to trample upon, tread down or under feet, Mat. 5.13; 7.6 Lu. 8.5; 12.1; met. to treat with contumely, spurn, He. 10.29. 159: Κατάπαυσις, εως, ἡ, pr. the act of giving rest; a state of settled cessation or rest, He. 3.11, 18; 4.3, 11, et al.; a place of rest, place of abode, dwelling, habitation, Ac. 7.49: from 160: Καταπαύω, (κατά & παύω) f. αύσω, to cause to cease, restrain, Ac. 14.18; to cause to rest, give rest to, introduce into a permanent settlement, He. 4.8; intrans. to rest, desist from, He. 4.4, 10. 161: Καταπέτασμα, ατος, τό, (καταπετάννυμι, to expand) a veil, curtain, Mat. 27.51. Mar. 15.38. Lu. 23.45. He. 6.19; 10.20. S. 162: Καταπίνω, (κατά & πίνω) f. πίομαι, a.2. κατέπῐον, a.1. pass. κατεπόθην, to drink, swallow, gulp down, Mat. 23.24; to swallow up, absorb, Re. 12.16. 2 Co. 5.4; to ingulf, submerge, overwhelm, He. 11.29; to swallow greedily, devour, 1 Pe. 5.8; to distroy, annihilate, 1 Co. 15.54. 2 Co. 2.7. 163: Καταπίπτω, (κατά & πίπτω) f. πεσοῦμαι, a.2. κατέπεσον, p. πέπτωκα, to fall down, fall prostrate, Ac. 26.14; 28.6. 164: Καταπλέω, (κατά & πλέω) f. εύσομαι, a.1. κατέπλευσα, to sail towards land, to come to land, Lu. 8.26.
- 68. 165: Καταπονέω, ῶ, (κατά & πονέω) f. ήσω, to exhaust by labour or suffering; to weary out, 2 Pe. 2.7; to overpower, oppress, Ac. 7.24. 166: Καταποντίζω, (κατά & ποντίζω, to sink, fr. πόντος) f. ίσω, to sink in the sea; pass. to sink, Mat. 14.30; to be plunged, submerged, Mat. 18.6 167: Κατάρα, ας, ἡ, (κατά & ἀρά) a cursing, execration, imprecation, Ja. 3.10. fr. the Heb. condemnation, doom, Ga. 3.10, 13. 2 Pe. 2.14; meton. a doomed one, one on whom condemation falls, Ga. 3.13: (ᾰρ)whence 168: Καταράομαι, ῶμαι, f. άσομαι, a.1. κατηρᾱσάμην, in N.T., p. pass. part. κατηραμένος, to curse, to wish evil to, imprecate evil upon, Mat. 5.44. Mar. 11.21, et al.; in N.T., pass. to be doomed, Mat. 25.41. 169: Καταργέω, ῶ, (κατά & ἀργός) f. ήσω, p. κατήργηκα, a.1. κατήργησα, p. pass. κατήργημαι, a.1. pass. κατηργήθην, to render useless or unproductive, occupy unprofitably, Lu. 13.7; to render powerless, Ro. 6.6; to make empty and unmeaning, Ro. 4.14; to render null, to abrogate, cancel, Ro. 3.3, 31. Eph 2.15, et al.; to bring to an end, 1 Co. 2.6; 13.8; 15.24, 26. 2 Co. 3.7, et al.; to destroy, annihilate, 2 Th. 2.8. He. 2.14; to free from, diserver from, Ro. 7.2, 6. Ga. 5.4. 170: Καταριθμέω, ῶ, (κατά & ἀριθμέω) f. ήσω,
- 69. 97 to enumerate, number with, count with, Ac. 1.17. 171: Καταρτίζω, (κατά & ἀρτίζω) f. ίσω, a.1. κατήρτισα, to adjust thoroughly; to knit together, unite completely, 1 Co. 1.10; to frame, He. 11.3; to prepare, provide, Mat. 21.16. He. 10.5; to qualify fully, to elevate to a complete standard, Lu. 6.40. He. 13.21. 1 Pe. 5.10; p. pass. κατηρτισμένος, fit, ripe, Ro. 9.22; to repair, refit, Mat. 4.21. Mar. 1.19; to supply, make good, 1 Th. 3.10; to restore to a forfeited condition, to reinstate, Ga. 6.1: whence 172: Κατάρτῐσις, εως, ἡ pr. a complete adjustment; a state of completeness, perfection, 2 Co. 13.9. L.G. 173: Καταρτισμός, οῦ, ὁ, completeness of qualification, a perfecting, Ep. 4.12. L.G. 174: Κατασείω, (κατά & σείω) f. σείσω, to shake down or violently; τὴω χεῖρε or τῇ χειρί, to wave the hand, beckon; to sign silence by waving the hand, Ac. 12.17, et al. 175: Κατασκάπτω, (κατά & σκάπτω) f. ψω, pr. to dig down under, undermine; by impl. to overthrow, demolish, raze, Ro. 11.3; τὰ κατεσκαμμένα, ruins, Ac. 15.16. 176: Κατασκευάζω, (κατά & σκευάζω, fr. σκεῦος) f. άσω, to prepare, put in readiness, Mat. 11.10. Mar. 1.2. Lu. 1.17; 7.27; to construct, form, build, He. 3.3, 4; 9.2, 6; 11.7. 1 Pe. 3.20. 177: Κατασκηνόω, ῶ, (κατά & σκηνόω, fr. σκηνή)
- 70. f. ώσω, to pitch one's tent; in N.T., to rest in a place, settle, abide, Ac. 2.26; to haunt, roost, Mat. 13.32. Mar. 4.32. Lu. 13.19: whence 178: Κατασκήνωσις, εως, ἡ, pr. the pitching a tent; a tent; in N.T., a dwelling-place; a haunt, roost, Mat. 8.20. Lu. 9.58. L.G. 179: Κατασκιάζω, (κατά & σκιάζω, idem) f. άσω, to overshadow, He. 9.5. 180: Κατασκοπέω, ῶ, (κατά & σκοπέω) f. κατασκέψομαι, in N.T., a.1. inf. κατασκοπῆσαι, to view closely and accurately; to spy out, Ga. 2.4. 181: Κατασκοπός, οῦ, ὁ, a scout, spy, He. 11.31. 182: Κατασοφίζομαι, (κατά & σοφίζω) f. ίσομαι, to exercise cleverness to the detriment of any one, to outwit; to make a victim of subtlety, to practise on by insidious dealing, Ac. 7.19. L.G. 183: Καταστέλλω, (κατά & στενός) f. στελῶ, a.1. κατέστειλα, p. pass. κατέσταλμαι, to arrange, dispose in regular order; to appease, quiet, pacify, Ac. 19.35, 36. 184: Κατάστημα, ατος, τό (καθίστημι) determinate state, condition; personal appearance, mien, deportment, Tit. 2.3. L.G. 185: Καταστολή, ῆς, ἡ, (καταστέλλω) pr. an arranging in order; adjustment of dress; in N.T., apparel, dress. 1 Ti. 2.9. 186: Καταστρέφω, (κατά & στρέφω)
- 71. f. ψω, to invert; to overturn, overthrow, throw down, Mat. 21.12. Mar. 11.15 187: Καταστρηνιάω, (κατά & στρηνιάω, to be headstrong, wanton, fr. στρηνίσ, v. στρηνός, hard, harsh) f. άσω, to be headstrong or wanton towards, 1 Ti. 5.11. N.T. 188: Καταστροφή, ῆς, ἡ, (καταστρέφω) an overthrow, destruction, 2 Pe. 2.6; met. overthrow of right principle or faith, utter detriment, perversion, 2 Ti. 2.14. 189: Καταστρώννυμι v. νύω, (κατά & στρώννυμι,— νύω) f. καταστρώσω, a.1. pass. κατεστρώθην, to strew down, lay flat; pass. to be strewn, laid prostrate in death, 1 Co. 10.5. 190: Κατασύρω, (κατά & σύρω) to drag down; to drag away, Lu. 12.58. (ῡ). 191: Κατασφάζω, v. σφάττω, (κατά & σφάζω v. σφάττω) f. σφάξω, to slaughter, slay, Lu. 19.27. 192: Κατασφρᾱγίζω, (κατά & σφραγίζω) f. ίσω, p. pass. κατεσφράγισμαι, to seal up, Re. 5.1 193: Κατάσχεσις, εως, ἡ, (κατέχω) a possession, thing possessed, A. 7.5. S. 194: Κατατίθημι, (κατά & τίθημι) f. θήσω, a.1. κατέθηκα, to lay down, deposit, Mar. 15.46; mid. to deposit or lay up for one's self; χάριν, v. χάριτας, to lay up a store of favour for one's self, earn a title to favour at the hands of a person, to curry favour with, Ac. 24.27; 25.9.
- 72. 98 195: Κατατομή, ῆς, ἡ, (κατατέμνω, to cut up, fr. κατά & τέμνω) concision, mutilation, Phi. 3.2. 196: Κατατοξεύω, (κατά & τοξεύω, to shoot with a bow) f. εύσω, to shoot down with arrows; to transfix with an arrow or dart, to transfix with an arrow or dart, He. 12.20. 197: Κατατρέχω, (κατά & τρέχω) f. δραμοῦμαι, a.2. έδρᾰμον, to run down, Ac. 21.32. 198: Καταφέρω, (κατά & φέρω) f. κατοίσω, a.1. pass. κατηνέχθην, to bear down; to overpower, as sleep, Ac. 20.9; καταφέρειν ψῆφον, to give a vote or verdict, Ac. 26.10. 199: Καταφεύγω, (κατά & φεύγω) f. ξομαι, a.2. κατέφῠγον, to flee to for refuge, Ac. 14.6. He. 6.18. 200: Καταφθείρω, (κατά & φθείρω) f. φθερῶ, f. pass. καταφθαρήσομαι,) to destroy, cause to perish, 2 Pe. 2.12; to corrupt, deprave, 2 Ti. 3.8. 201: Καταφῐλέω, ῶ, (κατά & φιλέω) f. ήσω, to kiss affectionately or with a semblance of affection, to kiss with earnest gesture, Mat. 26.49. Lu. 7.38. Ac. 20.37, et al. 202: Καταφρονέω, ῶ, (κατά & φρονέω) f. ήσω, pr. to think in disparagement of; to contemn, scorn, despise, Mat. 18.10. Ro. 2.4; to slight, Mat. 6.24. Lu. 16.13. 1 Co. 11.22. 1 Ti. 4.12; 6.2. 2 Pe. 2.10; to disregard, He. 12.2: whence
- 73. 203: Καταφρονητής, οῦ, ὁ, a contemner, despiser, scorner, Ac. 13.41. L.G. 204: Καταχέω, (κατά & χέω) f. εύσω, to pour down upon, Mat. 26.7. Mar. 14.3 205: Καταχθόνιος, ίου, ὁ, ἡ, (κατά & χθών, the earth) under the earth, subterranean, infernal, Phi. 2.10. 206: Καταχράομαι, ῶμαι, (κατά & χράομαι) f. ήσομαι, to use downright; to use up, consume; to make an unrestrained use of, use eagerly, 1 Co. 7.31; to use to the full, stretch to the utmost, 1 Co. 9.18. 207: Καταψύχω, (κατά & ψύχω) f. ξω, to cool, refresh, Lu. 16.24. (ῡ). 208: Κατείδωλος, ου, ὁ, ἡ, (κατά & εἴδωλον) rife with idols, sunk in idolatry, grossly idolatrous, Ac. 17.16. N.T. 209: Κατέναντι, (κατά & ἔναντι) adv. over against, opposite to, Mar. 11.2; 12.41; 13.3; ὁ, ἡ, τὸ κατέναντι, opposite, Lu. 19.30; before, in the presence of, in the sight, Ro. 4.17. S. 210: Κατενώπιον, (κατά & ἐνώπιον) adv. v. prep. in the presence of, in the sight of, 2 Co. 2.17; 12.19. Ep. 1.4. S. 211: Κατεξουσιάζω, (κατά & ἐξουσιάζω) f. άσω, to exercise lordship over, domineer over, Mat. 20.25. Mar. 10.42. N.T. 212: Κατεργάζομαι, (κατά & ἐργάζομαι) f. άσομαι,
- 74. to work out; to effect, produce, bring out as a result, Ro. 4.15; 5.3; 7.13. 2 Co. 4.17; 7.10. Phi. 2.12. 1 Pe. 4.3. Ja. 1.3; to work, practise, realise in practice, Ro. 1.27; 2.9, et al.; to work or mould into fitness, 2 Co. 5.5; to dispatch, subdue, Eph. 6.13. 213: Κατέρχομαι, (κατά & ἔρχομαι) f. ελεύσομαι, a.2. κατῆλθον, to come or go down, Lu. 4.31; 9.37; Ac. 8.5; 9.32, et al.; to land at, touch at, Ac. 18.22; 27.5. 214: Κατεσθίω, (κατά & ἐσθίω) f. καθέδομαι, a.2. κατέφᾰγον, to eat up, devour, Mat. 13.4, et al.; to consume, Re. 11.5; to expend, squander, Lu. 15.30; met. to make a prey of, plunder, Mat. 23.13. Mar. 12.40. Lu. 20. 47. 2 Co. 11.20; to vex, injure, Ga. 5.15. 215: Κατευθύνω, (κατά & εὐθύνω, fr. εὐθύς, straight) f. ῠνῶ, a.1. ῡηα, to make straight; to direct, guide aright, Lu. 1.79. 1 Th. 3.11. 2 Th. 3.5. 216: Κατέφαγον, a.2. of κατεσθίω. 217: Κατεφίστημι, (κατά & ἐφίστημι) intrans. a.2. κατεπέστην, to come upon suddenly, rush upon, assault, Ac. 18.12. N.T. 218: Κατέχω, (κατά & ἔχω) f. καθέξω, & κατασχήσω, imperf. κατεῖχον, a.2. κατέσχον, to hold down; to detain, retain, Lu. 4.42. Philem. 13; to hinder, restrain, 2 Th. 2.6, 7; to hold downright, hold in a firm grasp, to have in full and secure possession, 1 Co.
- 75. 99 7.30. 2 Co. 6.10; to come into full possession of, seize upon, Mat. 21.38; to keep, retain, 1 Th. 5.21; to occupy, Lu. 14.9; met. to hold fast mentally, retain, Lu. 8.15. 1 Co. 11.2; 15.2; to maintain, He. 3.6, 14; 10.23; intrans., a nautical term, to land, touch, Ac. 27.40; pass. to be in the grasp of, to be bound by, Ro. 7.6; to be afflicted with, Jno. 5.4. 219: Κατηγορέω, ῶ, (κατά & ἀγορεύω, to harangue) f. ήσω, to speak against, accuse, Mat. 12.10; 27.12. Jno. 5.45, et al.: whence 220: Κατηγορία, ας, ἡ, an accusation, crimination, Lu. 6.7, et al. 221: Κατήγορος, ου, ὁ an accuser, Jno. 8.10. Ac. 23.30, 35; 24.8, et al. 222: Κατήγωρ, ορος, ὁ an accuser, v.r. Re. 12.10, a barbarous form for κατήγορος. 223: Κατήφεια, ας, ἡ, (κατηφης, having a downcast look κατά & φάος) dejection, sorrow, Ja. 4.9. 224: Κατηχέω, ῶ (κατά & ἠχέω) f. ήσω, pr. to sound in the ears, make the ears ring; to instruct orally, inform by teaching, Lu. 1.4. 1 Co. 14.19, et al.; pass. to be made acquainted with, be informed of, learn by report, Ac. 21.21, 24. L.G. 225: Κατῑόω, ῶ, (κατά & ἰός) f. ώσω, p. pass. κατίωμαι, to cover with rust; pass. to rust, become rusty or tarnished, Ja. 5.3. L.G.
- 76. 226: Κατισχύω, (κατά & ἰσχύω) f. ύσω, to overpower, Mat. 16.18; intrans. to predominate, get the upper hand, Lu. 23.23. (ῡ). 227: Κατοικέω, ῶ, (κατά & οἰκέω) f. ήσω, trans. to inhabit, Ac. 1.19, et al.; intrans. to have an abode, dwell, Lu. 13.4, Ac. 11.29, et al.; to take up or find an abode, Ac. 7.2, et al.; to indwell, Eph. 3.17. Ja. 4.5, et al.: whence 228: Κατοίκησις, εως, ἡ, an abode, dwelling, habitation, Mar. 5.3. 229: Κατοικητήριον, ίου, τό, the same, Ep. 2.22. Re. 18.2. 230: Κατοικία, ας, ἡ, habitation, i.q. κατοίκησις, Ac. 17.26. L.G. 231: Κατοπτρίζω, (κάτοπτρον, a mirror) f. ίσω, to show in a mirror; to present a clear and correct image of a thing; mid. to have presented in a mirror, to have a clear image presented, or, perhaps, to reflect, 2 Co. 3.18. L.G. 232: Κατορθώμα, ατος, τό, (κατορθόω, to setup upright, accomplish happily, fr. κατά & ὀρθόω, to make straight) any thing happily and successfully accomplished; a beneficial and worthy deed, Ac. 24.3. L.G. 233: Κάτω, (κατά) adv. & pre. down, downwards. Mat. 4.6. Lu. 4.9; beneath, below, under, Mat. 27.51. Mar. 14.66, et al.; ὁ, ἡ, τὸ, κάτω, what is below, earthly, Jno. 8.23.
- 77. 234: Κατώτερος, α, ον, (comparat. fr. κάτω) lower, Ep. 4.9. 235: Κατωτέρω, (compar. of κάτω) adv. lower, further down; of time, under, Mat. 2.16. 236: Καῦμα, ατος, τό, (καίω) heat, scorching or burning heat, Re. 7.16; 16.9: whence 237: Καυματίζω, f. ίσω, to scrorch, burn, Mat. 13.6. Mar. 4.6. Re. 16.8, 9. L.G. 238: Καῦσις, εως, ἡ, (καίω) burning, being burned, He. 6.8: whence 239: Καυσόομαι, οῦμαι, to be on fire, burn intensely, 2 Pe. 3.10, 12. L.G. 240: Καύσων, ωνος, ὁ fervent scorching heat; the scorching of the sun, Mat. 20.12; hot weather, a hot time, Lu. 12.55; the scorching wind of the East, Eurus, Ja. 1.11. 241: Καυτηριάζω, (καυτήριον, an instrument for branding, fr. καίω) f. άσω, p. pass. κεκαυτηρίασμαι, to cauterise, brand; pass. met. to be branded with marks of guilt, or, to be seared into insensibility, 1 Ti. 4.2. 242: Καυχάομαι, ῶμαι, f. ήσομαι, a.1. ἐκαυχησάμνη, p. κεκαύχημαι, to glory, boast, Ro. 2.17, 23; ὑπέρ τινος, to boast of a person or thing, undertake a laudatory testimony to, 2 Co. 12.5; to rejoice, exult, Ro. 5.2, 3, 11, et al.: whence 243: Καύχημα, ατος, τό
- 78. 100 a glorying, boasting, 1 Co. 5.6; ground or matter of glorying or boasting, Ro. 4.2; joy, exultation, Phi. 1.26; laudatory testimony, 1 Co. 9.15, 16. 2 Co. 9.3, et al. 244: Καύχησις, εως, ἡ, a later equivalent to καυχημα, Ro. 3.27. 2 Co. 7.4, 14; 11.10, et al. 245: Κέδρος, ου, ἡ, a cedar, Jno. 18.1, where κέδρων is a false reading for the proper name Κεδρών. 246: Κεῖμαι, f. κείσομαι, to lie, to be laid; to recline, to be lying, to have been laid down, Mat. 28.6. Lu 2.12, el al.; to have been laid, placed, set, Mat. 3.10. Lu. 3.9. Jno. 2.6, et al.; to be situated as a city, Mat. 5.14. Re. 21.16; to be in store, Lu. 12.19; met. to be specially set, solemnly appointed, destined, Lu. 2.34. Phi. 1.17. 1 Th. 3.3; to lie under an influence, to be involved in, 1 Jno. 5.19. 247: Κειρία, ας, ἡ, a bandage, swath, roller; in N.T., pl. grave- clothes, Jno. 11.44. 248: Κείρω, f. κερῶ, a.1. mid. ἐκειράμην, to cut off the hair, shear, shave, Ac. 8.32; 18.18. 1 Co. 11.6, bis. 249: Κέλευσμα, ατος, τό, a word of command; a mutual cheer; hence, in N.T., a loud shout, an arousing outcry, 1 Th. 4.16: from 250: Κελεύω, (κέλω, κέλομαι, idem) f. εύσω, a.1 ἐκέλευσα, to order, command, direct, bid, Mat. 8.18; 14.19, 28, et al.
- 79. 251: Κενοδοξία, ας, ἡ emply conceit, vain glory, Phi. 2.3: from 252: Κενόδοξος, ου, ὁ, ἡ, (κενός & δόξα) vain-glorious, desirous of vain glory, Ga. 5.26. 253: Κενός, ή, όν, empty; having nothing, empty-handed, Mar. 12.3; met. vain, fruitless, void of effect, Ac. 4.25. 1 Co. 15.10; εἰς κενόν, in vain, to no purpose, 2 Co. 6.1, et al.; hollow, fallacious, false, Ep. 5.6. Col. 2.8; inconsiderate, foolish, Ja. 2.20. 254: Κενοφωνία, ας, ἡ, (κενός & φωνή) vain, empty babbling, vain disputation, fruitless discussion, 1 Ti. 6.20. 2 Ti. 2.16. N.T. 255: Κενόω, ῶ, (κενός) f. ώσω, a.1. ἐκένωσα, to empty, evacuate; ἑαυτόν, to divest one's self, of one's prorogatives, abase one's self, Phi. 2.7; to deprive a thing of its proper functions, Ro. 4.14. 1 Co. 1.17; to show to be without foundation, falsify, 1 Co. 9.15. 2 Co. 9.3. 256: Κέντρον, ου, τό, (κεντέω, to prick) a sharp point; a sting, Re. 9.10; a prick, stimulus, goad, Ac. 9.5; 26.14. met., of death, destructive power, deadly venom, 1 Co. 15.55, 56. 257: Κεντυρίων, ωνος, ὁ (Lat. centurio, fr. centum, a hundred) in its original signification, a commander of a hundred foot-soldiers, a centurion, Mar. 15.39, 44, 45. 258: Κενῶς (κενός)
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