MODERN WIRELESS NETWORKS

DINESH SURESH BHADANE
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Chapter-5
Modern Wireless Networks

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 5.1 Third Generation (3G)
Wireless Networks. [10]
 3G W-CDMA (UMTS) (Universal
mobile Telecommunication system.)
 3G CDMA 2000
 3G- TD-SCDMA (synchronous)
 Wireless local loop and LMDS (local
multipoint distribution)
 5.2 Wireless Local Area Networks
[10]
 Features of Bluetooth and Personal
Area Networks(PANS)
 Concept of Ad voc mobile
communication for 4G and 4.5G.
 4G wireless architecture and
capabilities, characteristics,
 MANET applications.
 Concept of Blockage, voice-channel
Blockage, call drops, voice quality,
word error rate.

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 Also known as ITU IMT-2000 Project.
 Started in- 1980.
 Goal: To have one world-wide standard and a common frequency band for
mobile networking.
 Mobility: quasi-stationary to high-speed platforms
 Global roaming: ubiquitous, seamless coverage
 Support data-intensive applications
 Increased data rates- 384 kbps while moving & 2 Mbps when stationary at
specific locations
 Increased capacity (more spectrally efficient)

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 Symmetrical and asymmetrical data transmission
 Circuit-switched and packet-switched-based services
 Speech quality comparable to wire-line quality
 Seamless incorporation of second-generation cellular system
 Several simultaneous services to end users for multimedia services
 Open architecture for the rapid introduction of new services and technology
 Multi-megabit internet access.
 Voice activated cells.
 Unparalleled network capacity.
 Ubiquitous “ always on” access.

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 Flexible support of multiple services
 Voice
 Messaging – email, fax, etc.
 Medium-rate multimedia – Internet access, educational
 High-rate multimedia – file transfer, video
 High-rate interactive multimedia – video teleconferencing,
telemedicine, etc.
 Communications using Voice Over Internet Protocol

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 High input fees for the 3G service licenses
 Inefficient to meet needs of future high-performance
 Multiple standards for 3G
 Lack of coverage because it is still new service
 Expensive fees for 3G Licenses Services
 It was challenge to build the infrastructure for 3G
 High Bandwidth Requirement
 Large Cell Phones

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Personal
Content
Communication
Productivity
Business

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3G STANDARDS
W-CDMA
(UMTS)
CDMA
2000
TD-
SCDMA
IMT 2000

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 Stands for Wideband CDMA.
 UMTS -The Universal Mobile Telecommunications System.
 UMTS is a visionary air interface standard.
 UMTS has developed since late 1996 by the ETSI.
 Backward compatibility- GSM, IS-136, PDC TDMA, 2.5G TDMA technologies.
 The network structure and bit level packaging of GSM data is retained by W-CDMA,
with additional capacity and bandwidth provided by a new CDMA air interface.
 The 3GPP standards body is developing W-CDMA for both wide area mobile cellular
coverage (using FDD) as well as indoor cordless type applications (using TDD).
 The W-CDMA air interface standard had been designed for “always-on” packet-based
wireless service, so that computers, entertainment devices, and telephones may all share
the same wireless network and be connected to the Internet, anytime, anywhere.

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 Support packet data rates up to 2.048 Mbps per stationary user
 Allows high quality data, multimedia, streaming audio, streaming video, and broadcast-type services
to consumers.
 Future versions of W-CDMA will support stationary user data rates in excess of 8 Mbps.
 Provides public and private network features, as well as videoconferencing and virtual home
entertainment (VHE).
 W-CDMA designers consider that broadcasting, mobile commerce, games, interactive video, and
virtual private networking will be possible throughout the world.
 Requires a minimum spectrum allocation of 5 MHz
 Wider air interface bandwidth of W-CDMA requires a complete change out of the RF equipment at
each base station.
 Each channel will be able to support between 100 and 350 simultaneous voice calls at once,
depending on antenna sectoring, propagation conditions, user velocity, and antenna polarizations.
 W-CDMA will provide at least a 6 times increase in spectral efficiency over GSM.

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State any four specifications of UMTS.(3G-
WCDMA)

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 It has a common world-wide spectrum band.
 More robust for multipath delays.
 Provides higher immunity towards frequency selective fading.
 Very high packet data rates of 2.048Mbps.
 Very high channel bandwidth of 5 MHz
 Backward compatibility- GSM systems.
 High frame structure of 16 slots per frame.
 It gives signals of higher voice and data quality and also small bit-error rates.
 Operate in multiple radio environments such as cellular, cordless, satellite, LAN etc.
 Wide range of telecommunication services such as voice, data, multimedia, internet.
 Global seamless (Smooth) connectivity (roaming).

16Channel Bandwidth 5 MHz
Duplex Mode FDD and TDD
Downlink RF Channel Structure Direct Spread (DS)
Chip Rate 3.84 Mcps
Frame Length 10 ms
Spreading Modulation Balanced QPSK (downlink), Dual-channel QPSK (uplink)
Complex spreading circuit
Data Modulation QPSK (downlink), BPSK (uplink)
Channel Coding Convolutional and turbo codes
Coherent detection User dedicated time multiplexed pilot (downlink and uplink) common pilot in downlink
Channel Multiplexing in
Downlink
Data and control channel are multiplexed
Channel Multiplexing in Uplink • Control and pilot channel time multiplexed
• I&Q multiplexing for data and control channel
Multirate Variable spreading and multicode
Spreading Factors 4-256 (uplink), 4-512 (downlink)
Power Control Open and fast closed loop (1.6 kHz)
Spreading (downlink) OVSF sequences for channel separation. Gold sequences 218-1 for cell and user
separation (truncated cycle 10 ms)
Spreading (uplink) OVSF sequences. Gold sequence 241 for user separation (different time shifts in I and Q

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1. State any four specifications of 3 G CDMA - 2000.
2. State the features of 3GCDMA-2000
3. Compare 3G WCDMA (UMTS) and 3G CDMA 2000
with respect to carrier spacing, chip rate, power control
frequency and coding.

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 Developed by- Working Group 45 of the Telecommunication Industry
Association (TIA) in US + participation of 3GPP2 working group.
 Up gradation of the existing 2G &2.5G CDMA Technology.
 Support much higher data rates as compared to 2G &2.5G CDMA Technology.
 The first 3G CDMA air interface, cdma2000 1xRTT, implies that a single 1.25
MHz radio channel is used (e.g. 1x simply implies one times the original CDMA-
One channel bandwidth, or, put another way, a multicarrier mode with only one
carrier).
 Within the ITU IMT-2000 body, cdma2000 1xRTT is also known as G3G-MC-
CDMA-1x. (MC Multicarrier, RTT Radio Transmission Technology)
 But it simply refer to the standard as CDMA-2000 1x.

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 CDMA-1x supports data rate of up to 307 kbps for a user in packet mode,
 Typical throughput rates of up to 144 kbps per user, depending on the number of
user, the velocity of a user, and the propagation conditions.
 CDMA-1x can also support up to twice as many voice users as the 2G CDMA
standard.
 Provides the subscriber unit with up to 2 times the standby time for longer lasting
battery life.
 CDMA-2000 is being developed for both FDD (mobile radio) and TDD (in-
building cordless) applications.
 To upgrade from 2G CDMA to CDMA-2000-1x, a wireless carrier merely needs to
purchase new backbone software and new channel cards at the base station, without
having to change out RF system components at the base station.

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 CDMA-2000 1xEV is an evolutionary advancement for CDMA originally developed
by Qualcomm as a proprietary high data rate (HDR) packet standard to be overlaid
upon existing IS-95, IS-95B, and CDMA-2000 networks.
 Qualcomm later modified its HDR standard to be compatible with W-CDMA as well,
and in August 2001, ITU recognized cdma2000 1xEV as part of IMT-2000.
 CDMA-2000 1xEV provides CDMA carriers with the option of installing radio
channels with data only (cdma2000 1xEV-DO) or with data and voice (cdma2000
1xEV-DV).
 With CDMA-2000 1xEV, individual 1.25 MHz channels may be installed in CDMA
base stations to provide specific high speed packet data access within selected cells.
 If CDMA-2000 1xEV -DO option is used , then data rates greater than 2.4 Mbps also
can be supported.

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 CDMA-2000 1xEV –DV supports both voice and data users, and can offer usable data rates up to 144
kbps with about twice as many voice channels as IS-95B.
 The best 3G solution for CDMA is called as CDMA2000 3xRTT standard uses three adjacent 1.25 MHz
radio channels that are used together to provide instantaneous packet data throughput speeds in excess of
2 Mbps per user, although actual throughput depends upon cell loading, vehicle speed, and propagation
conditions.
 Three non-adjacent radio channels may be operated simultaneously and in parallel as individual 1.25 MHz
channels (in which case no new RF hardware is required at the base station), or adjacent channels may be
combined into a single 3.75 MHz super channel (in which case new RF hardware is required at the base
station).
 With peak user data rates in excess of 2 Mbps, it is clear that cdma2000 3x has a very similar user data rate
throughput goal when compared to W-CDMA (UMTS).
 Advocates of cdma2000 claim their standard gives a wireless service provider a much more seamless and
less expensive upgrade path when compared to W-CDMA, since cdma2000 allows the same spectrum,
bandwidth, RF equipment, and air interface framework to be used at each base station as the 3G upgrades
are introduced over time.

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Parameter W-CDMA cdma2000
Carrier spacing 5 MHz 3.75 MHz
Chip rate 4.096 MHz 3.6864 MHz
Data modulation BPSK FW – QPSK; RV - BPSK
Spreading Complex (OQPSK) Complex (OQPSK)
Power control frequency 1500 Hz 800 Hz
Variable data rate implement. Variable SF; multicode Repet., puncturing, multicode
Frame duration 10 ms 20 ms (also 5, 30, 40)
Coding Turbo and convolutional Turbo and convolutional
Base stations synchronized? Asynchronous Synchronous
Base station acquisition/detect 3 step; slot, frame, code Time shifted PN correlation
Forward link pilot TDM dedicated pilot CDM common pilot
Antenna beam forming TDM dedicated pilot Auxiliary pilot

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Q- List the following parameters of 3G-TD-SCDMA system. (any four). (i) Bandwidth
(ii) Data Rate (iii) Multiple Access (iv) Backward Compatibility (v) Developed by
Ans:- (1) Bandwidth: 1.6MHZ
(2) Data Rate: Up to 384kbps of packet data rate,
(3) Multiple Access: Time division synchronous code division multiple access
technology.
(4) Backward Compatibility: GSM
(5) Developed by: China academy at telecomm (CATT) and Siemens corporation
jointly developed.

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 The most popular wireless air interface standard in China is GSM.
 The growth in number of wireless subscribers in China is tremendous as compared to rest of
the world.
 The China is willing to design its own wireless standard.
 The China Academy of Telecommunications Technology (CATT) and Siemens
Corporation jointly submitted an IMT-2000 3G standard proposal in 1998, based on Time
Division-Synchronous Code Division Multiple Access (TD-SCDMA).
 This proposal was adopted by ITU as one of the 3G options in late 1999.
 TD-SCDMA is based on the existing core GSM infrastructure and allows a 3G network to
evolve through the addition of high data rate equipment at each GSM base station.

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 TD-SCDMA combines TDMA and TDD techniques to provide a data-only overlay in an existing GSM
network.
 Packet Data Rate- Up to 384 kbps.
 Bandwidth- 1.6 MHz
 The radio channels are in and based on smart antennas, spatial filtering, and joint detection techniques.
 It has several times more spectrum efficiency than GSM.
 Frame Duration- 5 ms
 Frame is subdivided into seven time slots assigned flexibly to either a single high data rate user or
several slower users.
 By using TDD, different time slots within a single frame on a single carrier frequency are used to
provide both forward and reverse channel transmissions.
 In case of asynchronous traffic demand, e.g. downloading of a file, the forward link will require more
bandwidth than the reverse link, and thus more time slots will be dedicated to providing forward link
traffic than for providing reverse link traffic.

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It allows the 3G standard to be added to the existing GSM system very easily
and inexpensively because of TDD technique used in it.

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1. Sketch architecture of WLL system and list its advantages. (Any
two)
2. Draw neat figure of wireless local loop and state its importance.

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 Particularly in developing nations where there is inadequate telecommunications backbone infrastructure,
there is a tremendous need for inexpensive, reliable, rapidly deployable broadband connectivity that can
bring individuals and enterprises into the information age.
 Fixed wireless equipment is extremely well suited for rapidly deploying a broadband connection in many
instances, and this approach is steadily becoming more popular for providing “last mile” broadband
local loop access, as well as for emergency or redundant point-to-point or point-to-multipoint private
networks.
 Unlike mobile cellular telephone systems, fixed wireless communication systems are able to take
advantage of the very well-defined, time-invariant nature of the propagation channel between the fixed
transmitter and fixed receiver.
 Modern fixed wireless systems are usually assigned microwave or millimetre radio frequencies in the 28
GHz band and higher, which is >10 times the carrier frequency of 3G terrestrial cellular telephone

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 At these higher frequencies, the wavelengths are extremely small, which in turn allows very high gain
directional antennas to be fabricated in small physical form factors.
 At higher frequencies, too, more bandwidth can be easily used.
 Fixed wireless networks at very high microwave frequencies are only viable where there are no
obstructions, such as in a relatively flat suburban or rural setting.
 A vast array of new services and applications have been proposed and are in the early stages of
commercialization.
 These services include the concept of Local Multipoint Distribution Service (LMDS), which
provides broadband telecommunications access in the local exchange.
 In 1998, 1300 MHz of unused spectrum in the 27-31 GHz band was auctioned by the US
government to support LMDS. Similar auctions have been held in other countries around the world.

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 WLL stands for Wireless Local Loop.
 Microwave wireless links can be used to create a WLL.
 Local Loop is a network that exist between the central office (CO) and the individual
homes and business in adjacent to the central office (CO)
 In most developed countries, copper or optical fiber cable already has been
installed to residence and business.
 One more advantage of WLL is that we have to pay only once for that wireless
equipment, after there is no additional costs involved.
 System WLL is based on Cellular, satellite, microcellular technology.
 The WLL can greatly improve the telecommunication facilities and services in an
inexpensive way.

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Fast Development
Low Construction Cost
Low Operation and Maintenance Cost
Costumer Connection Cost
High Bandwidth Services Provision
Lower Network Extension Costs
High System Capacity

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 WLL is a new wireless option and comes under
the Fixed wireless as opposed to mobile.
Fixed here, refers to fixed location. It means
though the data transmission is wireless, the
stations are fixed, unlike in mobile where the
stations could be moving (assuming a station is
a subscriber).
 It is a broadband wireless point to multipoint
communication system
 Provides reliable digital two-way voice, data
and Internet services.
 "Local“ signals range limit.
"Multipoint“ broadcast signal from the
subscribers, "distribution“ wide range of
 data that can be transmitted, data ranging
anywhere from voice, or video to Internet and
video traffic.
 It provides high capacity.
 Spectrum Efficient.
 Promises to allow for a very high quality
communication services
 It transmits milliwave signals within small
cells.
 Designed for wireless digital television
transmission
 LMDS operates at frequencies >10Ghz range.
 Bandwidth- 1300MHz

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 Very small entry and setup costs.
 Systems can be setup with great ease and speed.
 All equipment can be carried and installed with great ease.
 Equipment can be setup only after a customer signs up.
 Thus the build out becomes "Demand Based" which is a major advantage when compared
to wired architectures.
 Less up-gradation cost.
 Less overhead of changing the transmission equipment
 No damage in transmission equipment.
 Once the basic infrastructure is handled, quality of service can be achieved.
 Bandwidth reuse is very high because of the cell structure used.
 Network management , maintenance and operation costs can be very less.

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Relatively high data rates
Capable of providing video, telephony, and data
Relatively low cost in comparison with cable alternatives

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It’s a new technology hence needs to prove itself.
The equipment's required for LMDS are millimetre
wave equipment's which are costly.
Line of sight problem, needs to see the antenna for
transmission.
Rain, snow and hail can create large changes in the
channel gain between the transmitter and receiver.

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1. LMDS is suitable for local exchange carrier application.
Justify and sketch its network diagram.
2. Describe operation of LMDS with suitable diagram

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LEC –Local Exchange Carrier
 In this network LEC uses a very wide BW ATM (Asynchronous Transfer
Mode) or a SONET(Synchronous Optical Network) backbone switch.
 This switch can connect very high speed data traffic to the internet, PSTN or
to its own private network.
 LMDS thus provides wireless broadband connectivity to the customers
without using the cables.

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Also known as WLAN in short or Wi-Fi.
Local area data network
Without wires
Mobile users can access information and network resources
through WLAN as they attends meetings, collaborate with other
users or move to other locations in the premises.
WLAN is not the a replacement for the wired infrastructure.
It is implemented as an extension to a wired LAN within a building
or campus.

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 Mobility-Productivity increases when people have access to data and information from any
location.
 Low implementation costs-WLAN are easy to set-up, relocate, change and manage.
 Installation speed and simplicity- WLAN is very fast and easy.
 Network expansion- It reaches where wires cannot reach.
 Reduced Cost-of-Ownership- Overall installation expenses and life cycle costs is expected to
be significantly lowered.
 Higher user to install base Radio- Wireless environment offers a higher user to capacity ratio.
 Reliability- WLAN is resistant to different types of cable failures.
 Scalability-WLAN can be configured in various topologies to meet the needs of specific
applications and installations.
 Usage of ISM band-No need of govt. license to use WLAN. It operates in India in 2.4GHz
band.

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 Office/Campus Environment- Such as in big buildings contains many floors
and rooms indoors and outdoors.
 Factory shop floor- Like in factory shop floor, warehouse, exhibition sites, retail
shops, labs etc.
 Homes- Convergence applications like different home devices like phones,
computers and appliances.
 Workgroup Environment- e.g.-Civil Construction sites
 Heritage Buildings- In very old national heritage if it is needed to set up Virtual
reality show then WLAN is useful.
 Public places- e.g.- Airports, Railway stations etc.
 War/Defence Sites

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802.11
HyperLAN
HomeRF
Bluetooth
MANET

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 Named after King Harald Bluetooth, the 10th century Viking who united Denmark and Norway, the Bluetooth
standard aims to unify the connectivity chores of appliances within the personal workspace of an individual.
 It is an open standard
 It provides an ad-hoc approach.
 Operating Range- nominal 10 meter range.
 Bluetooth operates in the 2.4 GHz ISM Band
 Uses a frequency hopping TDD scheme for each radio channel.
 Bandwidth- 1 MHz
 Hops at a rate of approximately 1600 hops/s.
 Transmissions are performed in 625 microsecond slots with a single packet transmitted over a single slot.
 For long data transmissions, particular users may occupy multiple slots using the same transmission frequency, thus
slowing the instantaneous hopping rate to below 1600 hops/second.
 Modulation -GFSK.
 Support operation in very high interference levels and relies on a number of forward error control (FEC) coding and
automatic repeat request (ARQ) schemes to support a raw channel bit error rate (BER) of about 10^-3 .

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1. State any four features of Bluetooth and PAN.
2. State any four features of Bluetooth.
3. State any four specifications of Personal Area
Network (PAN).

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 PAN is a networking feature of Bluetooth-enabled devices.
 Each Bluetooth device has the capability of sharing all of its features
with other Bluetooth devices in the surrounding area.
 Bluetooth phone can share information with a Bluetooth-enabled
computer or printer, just like one Bluetooth-enabled computer can link to
another.
 Bluetooth-enabled computer, sharing all the features, such as the Internet.
 Bluetooth devices can communicate at ranges of up to 10 meters.
 Bluetooth devices do not need to be in direct sight of each other.

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 Physical Layer- FHSS
 Frequency Band- 2.402-2.480 GHz
unlicensed ISM band
 Hop Frequency- 1600hops/s
 Data Rate- 1Mbps
 Operating Range- 10m
 Throughput- Around 720kbps
 Data and Network Security- Three
level of security, two levels of device
trust and three levels of service
security
 Transmit power- 1mW - 100mW
 No.of Channels- 79
 Supported Stations- 8
 Modulation- GFSK
 Duplexing-TDD

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 File transfer
 Internet Bridge
 LAN Access
 Synchronization
 Headset
 Vending Machine
 Smart Home systems
 Office and conference rooms with wireless devices
 Banking and other electronic payment systems

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Speed- 720 kbps
Frequency range- 2.4 GHz ISM band
Duplexing method- TDD
Modulation Technique- GFSK
Channel B.W- 1 MHz

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 In MANET, each node act as both host and router. (autonomous behaviour.)
 Multi-hop radio relaying- When a source node and destination node for a message is out of the radio
range, the MANETs are capable of multi-hop routing.
 Distributed nature of operation for security, routing and host configuration. A centralized firewall is
absent here.
 The nodes can join or leave the network anytime, making the network topology dynamic in nature.
 Mobile nodes are characterized with less memory, power and light weight features.
 The reliability, efficiency, stability and capacity of wireless links are often inferior when compared
with wired links.
 Mobile and spontaneous behaviour which demands minimum human intervention to configure the
network.
 All nodes have identical features with similar responsibilities and capabilities and hence it forms a
completely symmetric environment.
 High user density and large level of user mobility.
 Nodal connectivity is intermittent.(Stopping and starting at irregular intervals)

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 Mobile Adhoc Network (MANET) is an autonomous collection of mobile devices such as
laptops, smart phone etc. over wireless link and cooperate in a distributed manner to provide
necessary network functionality in the absence of a fixed infrastructure.
 This type of network operating as a standalone network or multiple point of attachment to
the cellular networks paves the way for numerous new and exciting applications
 MANET can be categorized into first, second and third generation.
 It has evolved to be a robust, reliable, operational experimental network.
 MANET allows users to access and exchange information regardless of their geographic
position or proximity to infrastructure.
 All modes in MANET are mobile and their connections are dynamic.
 It offers an advantageous decentralized character to the network.

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 An autonomous system of nodes (Mobile Hosts: MHs) connected by wireless
links
 Same channel used by all nodes
 Lack of fixed infrastructure (Infrastructure less)
 Absence of centralized authority
 Peer-to-peer connectivity
 Multi-hop forwarding to ensure network connectivity
 Topology may change dynamically
 Random Multi-hop Graph
 Energy-constrained
 Bandwidth-constrained, variable capacity links

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 Personal Area Networking
 Nodes could be attached to someone’s cell
phone, pulse watch, belt, etc.
 Bluetooth, printers, cell phones, PDAs, laptop
computers, headsets, etc.
 Military environments
 soldiers, tanks, planes
 Civilian environments
 taxi cab network
 meeting rooms
 sports stadiums
 boats, small aircraft
 Emergency operations
 search-and-rescue
 policing and fire fighting
 Crisis-management Applications
 Natural disasters with entire communications
infrastructure in disarray
 Restoring communications quickly is essential
 Infrastructure could be set up in hours instead
of days/weeks
 Collaborative Work
Collaborative computing might be important outside
office environments
 Telemedicine
 Tele geoprocessing Applications
 Virtual Navigation
 Education through Internet

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1. Write the concept of Ad-hoc mobile
communication for 4 G.
2. Draw architecture of 4G wireless system.
3. Draw 4G wireless architecture and state any four
features of 4G standard.

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 Started from late 2000s.
 One of the basic term used to describe 4G
is MAGIC.
 M-Mobile Multimedia
 A-Anytime Anywhere
 G-Global Mobility Support
 I-Integrated Wireless Solution
 C-Customized Personal Services
 Low Cost Per-bit
 Also known as Mobile Broadband
Everywhere
 Fully IP-based wireless internet.
 End-to-end QoS (Quality of service).
 High security.
 Always Be Connected (ABC).
 Faster and more reliable.
 High Capacity
 Terminal Heterogeneity
 Network Heterogeneity
 Wide Bandwidth
 Completely Packet Switched Networks
 Global Mobility and Service Portability
 Supports Bluetooth, Wi-Fi Wired and
Wireless Ad-Hoc Networking.

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 Higher bandwidth
 Better response time.
 Works at 2.6 GHz Frequency
 Less time to build 4G
 It use the same tower and fiber cables as
3Gs - they only have to upgrade the
towers with 4G components.
 IP + WPAN + WLAN + WMAN +
WWAN = 4G
 4g (LTE) Is Quicker Than 3g
 Less Buffering
 Better Audio Quality
 Improved Gaming Experience
 Streaming Services With Reduced Lag.
 Our 4g Plus Network Uses The 1800 &
2300 MHz Frequency Bands
 Our 3G Plus Network Uses The 900 &
2100 MHz Frequency Bands

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Expensive
Need more battery
Difficult to implement
Complex hardware design
It is impossible to make our current equipment to be
compatible with 4G.

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Mobiles
Tablets
4G Car
 Virtual Navigation
 Crisis Management
 Cameras in Traffic Light
 Tele-geoprocessiong applications
 First responder route selection
 Tele-medicine and Education
 Traffic Control during
Disasters
 Multimedia- Video Services
 Sensors in public vehicle
 Virtual Presence

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Specifications 3G 4G
Frequency Band 1.6 - 2.5 GHz 2 – 8 GHz
Bandwidth 5-20 MHz ≥100 MHz
Data rate Up to 2Mbps Upto 1Gbps
Access WCDMA or
CDMA-2000
Multi-carrier – CDMA or
OFDM(TDMA)
FEC Turbo-codes Concatenated codes
Switching Circuit/Packet Packet

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1. Define the term blockage, call drops, word error rate and voice
quality.
2. State the concept of following terms. (i) Voice channel blockage (ii)
Call drops (iii) Voice quality (iv) Ward error rate

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Voice Channel
Blockage
Setup Channel
Blockage
Blockage

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 The mobile unit finds the busy/ ideal bit in the forward set-up channel to set up a call.
 If the busy bit does not modify after 10 attempts in a period of 1 sec a busy tone will be
generated and no transmissions will takes place from the mobile.
 However if the ideal bit is seen mobile transmissions occurs.
 To a mobile number many calls can inter collide simultaneously.
 If this number exceeds 10 then the mobile call is said to be blocked.
 This blockage is called as Set-up Channel blockage.
 It can be detected by the mobile phone users only.
 This blockage should be less than half of the blockage indicated by the mobile cellular system.

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 Simultaneously when many calls come in ,some calls are rejected because
there are no voice channels available and this blockage is called as voice
channel blockage.
 This blockage can be found at the cell location.

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 Call drop is also known as Lost Calls.
 It is defined as the calls that are dropped(lost) because of factors after
the voice channel is allocated to a mobile because of weak signals.
 It depends on hand off traffic model and signal coverage.

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 WER is a common metric of the performance of a speech
recognition or machine translation system
 It is given as
WER= (S+D+I)/N
 Where, S= no. of substitutes;
D= no of deletions;
I= no of insertions;
N= no of words in the reference.

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It is nothing but signal to noise plus distortion ratio
(SINAD).
Usually expressed in dB
It is quoted alongside the receiver RF sensitivity, to give a
quantitative evaluation of the receiver sensitivity.
Performance of a system is evaluated to compute the voice
quality over a service area.

THANK YOU !
79
End of Presentation

MODERN WIRELESS NETWORKS

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MODERN WIRELESS NETWORKS