Ch4

Mobile Computing

Chapter 4
Emerging Technologies
Asoke K Talukder
Hasan Ahmed
© Tata McGraw Hill

Emerging Technologies
 Bluetooth
 Radio Frequency Identification (RFID)
 WiMAX
 Mobile IP
 IPv6
 Java Card

Bluetooth
 Name comes from nickname of Danish king Harald Blåtand
 Allows users to make ad hoc wireless connections between
devices like mobile phones, desktop or notebook computers
wirelessly
 Data transfer at a speed of about 720 Kbps within 50 meters
(150 feet) of range or beyond through walls, clothing and even
luggage bags
 Built into a small microchip
 Operates in a globally available frequency band ensuring
worldwide interoperability
 Managed and maintained by Bluetooth Special Interest Group

Bluetooth Protocol

 Uses the unlicensed 2.4 GHz ISM (Industrial Scientific and
Medical) frequency band
 79 available channels spaced 1 MHz apart from 2.402 GHz to
2.480 GHz
 Allows power levels starting from 1mW (covering 10
centimetres) to 100mW (covering upto 100 meters) suitable for
short device zone to personal area networks within a home
 Supports both unicast (point-to-point) and multicast (point-to-
multipoint) connections
 Bluetooth protocols are a collection of many inter-related
protocols

Bluetooth Protocol

 Uses the master and slave relationship
 Master and slaves together form a Piconet when master allows
slaves to talk
 Up to seven ‘slave’ devices can be set to communicate with a
‘master’ in a Piconet
 Scatternet is formed when several of piconets are linked
together to form a larger network in an ad hoc manner

Bluetooth Protocol
 Scatternet is a topology where a device from one piconet also
acts as a member of another piconet wherein a device being a
master in one piconet can simultaneously be a slave in the other
one

Bluetooth Protocol

 Bluetooth Core protocols plus Bluetooth radio protocols are
required by most of Bluetooth devices
 Uses spread spectrum technologies at the Physical Layer while
using both direct sequence and frequency hopping spread
spectrum technologies
 Uses connectionless (ACL–Asynchronous Connectionless
Link) and connection-oriented (SCO–Synchronous Connection-
oriented Link) links
 Cable Replacement layer, Telephony Control layer and
Adopted protocol layer form application-oriented protocols

Bluetooth Protocol Stack

OBEX – Object Exchange Protocol TCS BIN – Telephony Control Specification Binary
WAE – Wireless Application Environment SDP – Service Discovery Protocol
WAP – Wireless Application Protocol RFCOMM – Radio Frequency Communication
LMP – Link Manager Protocol L2CAP – Logical Link Control and Adaptation Protocol

Bluetooth Protocol Stack

1. Bluetooth Core Protocols
2. Cable Replacement Protocol
3. Telephony Control Protocols
4. Adopted Protocols

Bluetooth Core Protocols

 Baseband – enables physical RF link
 Link Manager Protocol (LMP) – manages devices in
range, power modes, connections, duty cycles, etc.
 Logical Link Control and Adaptation Protocol (L2CAP) –
segmentation and re-assembly of fragmented packets with their
multiplexing
 Service Discovery Protocol (SDP) – Enables a device to join a
piconet

Cable Replacement Protocol

 Radio Frequency Communication (RFCOMM) - emulates RS-
232 control and data signals over Bluetooth baseband protocol

Telephony Control Protocols

 Telephony Control Specification Binary (TCS BIN) - defines
the call control signaling protocol and handles mobility
management for groups of Bluetooth TCS devices
 Attention (AT) Commands - defines a set of commands by
which a mobile phone can be used and controlled as a modem for
fax and data transfers

Adopted Protocols

 Point-to-Point Protocol (PPP) - means of taking IP packets
to/from the PPP layer and placing them onto the LAN
 Transmission Control Protocol/Internet Protocol (TCP/IP) -
used for communication across the Internet
 Object Exchange (OBEX) Protocol - session protocol to
exchange objects and used to browse the contents of folders on
remote devices
 Content Formats - used to exchange messages and notes and
synchronize data amongst various devices

Bluetooth Security

 Offers security infrastructure starting from authentication, key
exchange to encryption
 Uses the publicly available cipher algorithm known as
SAFER+ to authenticate a device’s identity

Bluetooth Application Models

Each application model in Bluetooth is realized through a Profile.
Profiles define the protocols and protocol features supporting a
particular usage model. Some common profiles are:

 File Transfer
 Internet Bridge
 LAN Access
 Synchronization
 Headset

RFID

 Radio Frequency Identification
 Radio transponder (known as RFID tags) carrying an ID
(Identification) can be read through radio frequency (RF)
interfaces
 Tag is attached to the object and data within the tag provides
identification for the object
 Object could be an entity in a manufacturing shop, goods in
transit, item in a retail store, a vehicle in a parking lot, a pet, or a
book in a library

RFID System

Comprises of different functional areas like:
 Means of reading or interrogating the
 Mechanism to filter some of the data
 Means to communicate the data in the tag with a host computer
 Means for updating or entering customized data into the tag

RFID Tags

Three basic criteria for categorisation:
 Frequency
 Application
 Power levels

RFID tags based on frequency

 Works on six frequencies of 132.4 KHz, 13.56 MHz, 433
MHz, 918 MHz, 2.4 GHz and 5.8 GHz
 Low frequency range tags are slow in data transfer and suitable
for slow moving objects, security access, asset tracking and
animal identification applications
 High frequency range tags offer long reading ranges and high
data transfer speed and are used for fast moving objects like
railway wagon tracking and identification of vehicles on freeways
for automated toll collection
 Higher the frequency, higher the data transfer rates

RFID tags based on applications

 Speed of the object and distance to be read determines the type
of tag to be used
 RFID systems follow contact-less and non line-of-sight nature
of the technology
 Tags can be read at high speeds
 RFID tag contains two segments of memory - one segment is a
factory set and used to uniquely identify a tag while the other one
is used by the application
 Read/write capability of a RFID system is an advantage in
interactive applications such as work-in-process or maintenance
tracking

RFID tags based on power levels

 Two types - Active and Passive tags
 Passive tags are generally in low frequency range
 Tags at higher frequency range can be either active or passive

Active Tags

 Powered by an internal battery and are typically read/write
 Memory can vary from a few bytes to 1MB
 Battery supplied power of an active tag generally gives it a
longer read range
 Greater the size, greater the cost and a limited operational life

Passive Tags

 Operate without own power source
 Obtains operating power from the reader’s antenna
 Data within a passive tag is read only and generally cannot be
changed during operation
 Lighter, less expensive and offer a virtually unlimited
operational life
 Have shorter read ranges than active tags and require a high
powered reader
 Data is usually 32 to 128 bits long

Components of an RFID system

 A transponder programmed with unique information (RFID
tag)
 A transceiver with decoder (a reader)
 An antenna or coil
Close proximity passive tags rely on electromagnetic or inductive
coupling techniques whereas active tags are based upon
propagating electromagnetic waves techniques

Coupling in Passive and Active RFID tags

(a) Passive RFID tags (b) Active RFID tags

Application areas for RFID
 Transportation and Logistics
 Manufacturing and Processing
 Security
 Animal tagging
 Retail store and enterprise stores
 Community library
 Time and attendance
 Postal tracking
 Airline baggage reconciliation
 Road toll management

Wireless Broadband

 Also known as Wireless Metropolitan Area Network (Wireless
MAN) and Wireless Microwave Access (WiMAX)
 IEEE 802.16 standard released in April 2002
 Offers an alternative to high bandwidth wired access networks
like fiber optic, cable modems and DSL
 Provides network access to buildings through exterior antennas
communicating with radio base stations
 Networks can be created in just weeks by deploying a small
number of base stations on buildings or poles to create high
capacity wireless access systems

Sub-standards of IEEE 802.16

 IEEE 802.16.1 - Air interface for 10 to 66 GHz
 IEEE 802.16.2 - Coexistence of broadband wireless access
systems
 IEEE 802.16.3 - Air interface for licensed frequencies, 2 to 11
GHz

Basics of IEEE 802.16

IEEE 802.16 standards are concerned with the air interface
between a subscriber’s transceiver station and a base transceiver
station
 The Physical Layer
 MAC Layer
 Convergence Layer

Physical Layer

 Specifies the frequency band, the modulation scheme, error-
correction techniques, synchronization between transmitter and
receiver, data rate and the multiplexing structure
 Both TDD and FDD alternatives support adaptive burst profiles
in which modulation and coding options may be dynamically
assigned on a burst-by-burst basis
 Three physical layer for services: Wireless MAN-
SC2, Wireless MAN-OFDM and Wireless MAN-OFDMA

Medium Access Control Layer

 Designed for point-to-multipoint broadband wireless access
 Addresses the need for very high bit rates, both uplink (to the
base station) and downlink (from the base station)
 Services like multimedia and voice can run as 802.16 MAC is
equipped to accommodate both continuous and bursty traffic

Convergence Layer

 Provides functions specific to the service being provided
 Bearer services include digital audio/video multicast, digital
telephony, ATM, Internet access, wireless trunks in telephone
networks and frame relay

Mobile IP
 ‘Mobile IP’ signifies that, while a user is connected to
applications across the Internet and the user’s point of attachment
changes dynamically, all connections are maintained despite the
change in underlying network properties
 Similar to the handoff/roaming situation in cellular network
 Mobile IP allows the mobile node to use two IP addresses
called home address and care of address
 The home address is static and known to everybody as the
identity of the host
 The care of address changes at each new point of attachment
and can be thought of as the mobile node’s location specific
address

Working of Mobile IP
Let’s take the case of mobile node (A) and another host (server X).
The following steps take place:
 Server X wants to transmit an IP datagram to node A. The home
address of A is advertised and known to X. X does not know
whether A is in the home network or somewhere else. Therefore, X
sends the packet to A with A’s home address as the destination IP
address in the IP header. The IP datagram is routed to A’s home
network.


 At the A’s home network, the incoming IP datagram is
intercepted by the home agent. The home agent discovers that A is
in a foreign network. A care of address has been allocated to A by
this foreign network and available with the home agent. The home
agent encapsulates the entire datagram inside a new IP
datagram, with A’s care of address in the IP header. This new
datagram with the care of address as the destination address is
retransmitted by the home agent.
 At the foreign network, the incoming IP datagram is intercepted
by the foreign agent. The foreign agent is the counterpart of the
home agent in the foreign network. The foreign agent strips off
the outer IP header, and delivers the original datagram to A.


 A intends to respond to this message and sends traffic to X. In
this example, X is not mobile; therefore X has a fixed IP address.
For routing A’s IP datagram to X, each datagram is sent to some
router in the foreign network. Typically, this router is the foreign
agent. A uses X’s IP static address as the destination address in the
IP header.
 The IP datagram from A to X travels directly across the
network, using X’s IP address as the destination address.


 Discovery - A mobile node uses a discovery procedure to
identify prospective home agents and foreign agents.
 Registration - A mobile node uses a registration procedure to
inform its home agent of its care-of address.
 Tunneling - Tunneling procedure is used to forward IP
datagrams from a home address to a care of address.

Cellular IP

None of the nodes know the exact location of a mobile host.
Packets addressed to a mobile host are routed to its current base
station on a hop-by-hop basis where each node only needs to
know on which of its outgoing ports to forward packets. This
limited routing information (referred as mapping) is local to the
node and does not assume that nodes have any knowledge of the
wireless network topology. Mappings are created and updated
based on the packets transmitted by mobile hosts.

Cellular IP

 Uses two parallel structures of mappings through Paging
Caches (PC) and Routing Caches (RC)
 PCs maintain mappings for stationary and idle (not in data
communication state) hosts
 RC maintains mappings for mobile hosts
 Mapping entries in PC have a large timeout interval, in the
order of seconds or minutes. RCs maintain mappings for mobile
hosts currently receiving data or expecting to receive data

Relationship between Mobile IP and Cellular
IP

Internet Protocol version 6

 Successor to today’s IP version 4 protocol (IPv4)
 Internet Engineering Task Force (IETF) has produced a
comprehensive set of specifications (RFC
1287, 1752, 1886, 1971, 1993, 2292, 2373, 2460, 2473, etc.) that
define the next-generation IP protocol originally known as ‘IPNg’
 Uses 128 bit addresses for each packet creating a virtually
infinite number of IP addresses (approximately 3.4*10**38 IP
addresses) as opposed to 3758096384 IPv4 addresses

IPv6

 There are global addresses and local addresses
 Global addresses are used for routing of global Internet
 Link local addresses are available within a subnet
 IPv6 uses hierarchical addressing with three level of addresses
 Includes a Public Topology (the 48 bit external routing prefix)
 Site Topology (typically a 16 bit subnet number)
 Interface Identifier (typically an automatically generated 64 bit
number unique on the local LAN segment)

Hierarchical addressing of IPv6

IPv6 Security

 Comes native with a security protocol called IP Security
(IPSec)
 IPSec protocol is a standards-based method of providing
privacy, integrity and authenticity to information transferred
across IP networks

Features of IPSec
 Diffie-Hellman key exchange mechanism for deriving key
between peers on a public network
 Public key cryptography to guarantee the identity of the two
parties and avoid man-in-the-middle attacks
 Bulk encryption algorithms, such as 3DES, for encrypting the
data
 Keyed hash algorithms, such as HMAC, combined with
traditional hash algorithms such as MD5 or SHA for providing
packet authentication
 Digital certificates signed by a certificate authority to act as
digital ID cards
 IPSec provides IP network layer encryption

Migrating from IPv4 to IPv6

 Migration of the network components to be able to support
IPv6 packets. Using IP tunneling, IPv6 packets can propagate over
an IPv4 envelope. Existing routers can support IP tunneling.
 Migration of the computing nodes in the network. This will
need the operating system upgrades so that they support IPv6
along with IPv4. Upgraded systems will have both IPv4 and IPv6
stacks.
 Migration of networking applications in both client and server
systems. This requires porting of the applications from IPv4 to
IPv6 environment.

Interconnecting IPv6 networks

 Tunneling is one of the key deployment strategies for both
service providers as well as enterprises during the period of IPv4
and IPv6 coexistence.
 Tunneling service providers can offer an end-to-end IPv6
service without major upgrades to the infrastructure and without
impacting current IPv4 services.

Tunneling Mechanisms

 Manually created tunnels such as IPv6 manually configured
tunnels (RFC 2893)
 IPv6 over IPv4 tunnels
 Semiautomatic tunnel mechanisms such as that employed by
tunnel broker services
 Fully automatic tunnel mechanisms such as IPv4 compatible

Mobile IP with IPv6
 IPv6 with hierarchical addressing scheme can manage IP
mobility much efficiently.
 IPv6 also attempts to simplify the process of renumbering
which could be critical to the future routing of the Internet traffic.
 Mobility Support in IPv6, as proposed by the Mobile IP
working group, follows the design for Mobile IPv4. It retains the
ideas of a home network, home agent and the use of encapsulation
to deliver packets from the home network to the mobile node’s
current point of attachment.
 While discovery of a care of address is still required, a mobile
node can configure its a care of address by using Stateless
Address Auto-configuration and Neighbor Discovery. Thus,
foreign agents are not required to support mobility in IPv6.

Java Card

 Smart card with Java framework
 Smart card is a plastic card with intelligence and memory
 A smart card is embedded with either (i) a microprocessor and
a memory chip or (ii) only a memory chip with non-
programmable logic
 A microprocessor card can have an intelligent program resident
within the card which can add, delete, and otherwise manipulate
information on the card
 A memory card can store some information for some pre-
defined operation

Java Card

 Java was chosen as the vehicle for interoperability
 All the microprocessor based smart cards now offer Java API
framework on the smart card
 Java Card technology preserves many of the benefits of the
Java programming languages such as
productivity, security, robustness, tools, and portability
 For Java card, the Java Virtual Machine ( JVM), the language
definition, and the core packages have been made more compact
to bring Java technology to the resource constrained smart cards

Functioning of Java Card

 Java card technology supports OTA (Over The Air) downloads
 Applications written for the Java Card platform are referred to
as applets
 Challenge of Java Card technology on smart card is to fit Java
system software in a resource constraint smart card while
conserving enough space for applications
 The Java Card virtual machine on a smart card is split into two
parts; one that runs off-card and the other that runs on-card

 Many processing tasks that are not constrained to execute at
run time, such as class loading, bytecode verification, resolution
and linking, and optimization, are dedicated to the virtual machine
that is running off-card where resources are usually not a concern
 The on-card components of Java Card include components like
the Java card virtual machine ( JCVM), the Java card runtime
environment ( JCRE), and the Java API
 Task of the compiler is to convert a Java source into Java class
files
 The converter will convert class files into a format
downloadable into the smart card while ensuring the byte code
validity


The converter checks the classes off-card for
 Well formedness
 Java Card subset violations
 Static variable initialization
 Reference resolution
 Byte code optimization
 Storage Allocation.
 The java card interpreter
 Executes the applets
 Controls run-time resources
 Enforces runtime security

 Following conversion by the off-card VM into CAP (Converted
APlet) format, the applet is transferred into the card using the
installer
 Applet is selected for execution by the JCRE
 JCRE is made up of the on-card virtual machine and the Java
Card API classes and performs additional runtime security checks
through applet firewall
 Applet firewall partitions the objects stored into separate
protected object spaces, called contexts and controls the access to
shareable interfaces of these objects
 It is then executed on JVCM which is scaled down version of
standard JVM ( Java Virtual Machine)

Next Chapter

Global System for Mobile Communications (GSM)

Thanks

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