2017104419250_Chapter-1 Introduction.pdf

EC 6515
MOBILE COMMUNICATIONS
3 credits [3-0-0]

Course Contents
• Introduction to Wireless Communication Systems- Evolution, Mobile Systems around the World,
Example of the mobile radio systems, recent trends, 1G, 2G, 3G, 4G and 5G Cellular networks
• The Cellular Concept - Frequency reuse, Channel assignment, Hand off process, Interference.
• Mobile Radio Propagation - Path loss, Radio wave propagation, Reflection, Diffraction,
Scattering, link budget; Outdoor and indoor propagation models;
• Principle of multi path propagation - Impulse response model of channels, parameters for
mobile multi path channels, concept of fading, Rayleigh and Ricean fading; simulation of fading
channels.
• Modulations techniques for mobile communication:- Linear Modulation techniques, constant
envelop modulation, QPSK, MSK, GMSK, spread spectrum modulation techniques.
• Equalization, Diversity and Channel coding:- Fundamentals, General adaptive equalizer, Linear
and non-linear equalizers, diversity techniques, RAKE receivers. Basic concept of coding.
• Multiple access techniques: - Introduction, FDMA, TDMA, CDMA, SDMA, capacity of cellular
systems.
• Introduction to OFDM and wireless LAN.
18-08-2022 Poonam Singh EC Dept, NIT Rourkela 2

Books
Essential Reading:
• T.S. Rappaport, Wireless Communications – Principles and Practice, Prentice Hall of
India/ Pearson Education India, 2002.
• W C Y Lee; Mobile Communication Engineering, Tata McGraw Hill, India, 2008
Supplementary Reading:
• W.C.Y. Lee, Digital Cellular Systems, Mc Graw Hill, 2000.
• G. Stuber; Principles of Mobile Communication, 2001, Springer

Chapter 1: Introduction to Wireless
Communication Systems

Introduction to Wireless Communication Systems
• Communication is an essential need of human being, e.g., conversation, letter
• “Wireless” used to be the only (limited and unreliable) way to communicate in
ancient times
• Modern wireless communications are based on the electromagnetic field theory
(Maxwell’s equations, Marconi’s invention)
Wireless is often prior to its wired counterpart and has become an important
supplement:
• Marconi’s Wireless Telegraph  Wired Telegraph & Telephone  Cordless, Cellular
Telephone, and Wireless Local Loop
• Broadcast TV  Cable TV  Satellite TV
• Aloha Network  Ethernet  Wireless LAN

Characteristics of Wireless Communication
• Convenience and reduced cost
– Service can be deployed faster than fixed service
– No cost of cable plant
– Service is mobile, deployed almost anywhere
• Unreliable channel (attenuation, fading, shadowing, interference)
• Complicated design and management
• Device limitations (power supply, LCD)
• Limited bandwidth and expensive service

Applications
• Mobile workers
– access to customer files and company documents stored in a central location
– collaborative work environments
– access to email and voice messages
• Replacement of fixed networks
– remote sensors, e.g. weather, environment, road conditions
– flexible work spaces
– LANs in legacy buildings
• Entertainment, education, ...
– outdoor Internet access
– intelligent travel guide with up-to-date location dependent information
– ad-hoc networks for multi user games

Applications
• Vehicles
– transmission of news, road conditions, weather
– personal communication using cellular
– position identification via GPS
– inter vehicle communications for accident prevention
– vehicle and road inter communications for traffic control, signaling, data gathering
– ambulances, police, etc.: early transmission of patient data to the hospital, situation reporting
– entertainment: music, video

Evolution of Wireless Systems
• Guglielmo Marconi invented the wireless telegraph in 1896
• First public mobile (car-based) telephone system (MTS) introduced in 1946
– Analog frequency modulation
– High power BS tower to cover 50 miles radius
– Inefficient (120K spectrum for a voice connection)
• Improved mobile telephone system (IMTS) developed in 1960
– Full duplex services and direct-dialing
– 23 FM channels with BW reduced to 25-30 KHz
• Cellular concept
– Exploits the attenuation of radio signal with distance to achieve frequency reuse.
– originally proposed by D. H. Ring in 1947
– Bell Labs began work on cellular telephone system in the late 1960s.

Evolution of Wireless Sys. (1G)
• 1G Cellular System
– Designed in 1970s, deployed in early 1980s
– Analog, 42 control channels, 790 voice channels
– Data Rate 2.4 to 14.4 kbps
– Handoff performed at BS based on received power
– AMPS in US; TACS in part of Europe; NTT in Japan; C450 in West German, and
NMT in some countries.
– Became highly popular

• 2G Systems
– Digital cellular telephony
– Modest data support, incompatible
– Data Rate 14.4 to 64 kbps
– GSM: a common TDMA technology for Europe; claim about 3/4 of subscribers
worldwide.
– IS-54 and IS-136: TDMA technology in US; compatible with AMPS;
– IS-95: CDMA; standardized in 1993; South Korea and Hong Kong deployed it in
1995; US in 1996.

Evolution of Wireless Sys. (2.5G)
• 2G telephony is highly successful
• Data Rates 144-384 kbps
• Enhancement to 2G on data service
– GSM: HSCSD, EDGE and GPRS
– IS-95: IS-95b
– IS-136: D-AMPS+ and CDPD
• The improved data rate is still too low to support multimedia traffic
• ITU initiated 3G standardization effort in 1992, the outcome is IMT-2000.

IMT-2000 comprises several 3G standards:
• EDGE, data rate up to 473Kbps, backward compatible with GSM/IS-136
• cdma2000 (Qualcomm), data rate up to 2Mbps, backward compatible
with IS-95
• WCDMA (Europe), introduces a new 5MHz channel structure; data rate
up to 2Mbps;
• TD-SCDMA (China), CDMA in TDD fashion
• Data Rates 144 kbps to 2 Mbps

Evolution of Mobile Radio Communications
AMPS
Voice
Service
Track
CDMA
IS-95
CDMA
2000
4G
ETACS GSM
WCDMA
1st Generation
Analog
2nd Generation
Digital
3rd Generation
Wideband
Fixed
Computer
Network
WLAN
PDMA
North
America
Europe
Data
Service
Track
Voice & Data
Service
Track
4th Generation
Wideband All-IP
Notes:
IP: Internet Protocol
TCP: Transmission Control Protocol
AMPS: Advanced Mobile Phone Services
ETACS: European Total Access Communication System
PDMA: Packet Division Multiple Access (Hanwang, China)
Circuit Switching
Packet Switching
Circuit and Packet Switching
evolving to Packet Switching
TD-
SCDMA
China

Paradigm From 1G to Beyond 3G
First Generation
• Analogue
• Circuit switched
• Basic voice telephony
• Low capacity
• Limited local and
regional coverage
Second Generation
• Digital
• Circuit switched
• Voice plus basic data
applications
• Low data speed
• Enhancements towards
• packet switching
• higher data rates
• Trans-national and global
roaming
• Digital
• Packet and circuit
switched
• Advanced data
(multimedia) applications
• Fast data access
• Global coverage
• Global roaming
Third Generation
Beyond Third
Generation
• Digital
• Packet switched
• All IP based (IPv6)
• More advanced
multimedia applications
• User in control
• Flexible platform of
complementary access
systems
• High speed data
• Improved QoS
• Global coverage
• Global roaming

Mobile Radio Transmission
Mobile Radio Transmission can be of 3 types:
• Simplex - Communication in one direction only e.g. paging, TV, Radio
• Half Duplex – Two way communication, but uses the same radio channel
for both transmission and reception, a user can only transmit or receive
at a time e.g. walkie-talkie
• Full Duplex – Two way simultaneous communication e.g. Telephone

Duplexing
• Frequency Division Duplexing (FDD)
– A pair of simplex channels with a fixed and known frequency separation used for
uplink and downlink
– A duplexer is used to enable the same antenna to be used for simultaneous
transmission and reception
• Time Division Duplexing (TDD)
– Single radio channel is used for uplink and downlink in different time slots
– Used with digital transmission formats

Spectrum allocation for US Cellular

Paging System

Paging Systems
• Sends brief messages to a subscriber
• Typically used to notify a subscriber
– News headlines
– Promotional messages, offers
• Issued message is called a page
• Provide reliable communication to subscribes wherever they are
• Require large transmitter powers (kilowatts) and low data rates (1-2
kbps) for maximum coverage from each base station

Paging
• Simple paging systems are simple and inexpensive - may cover limited
area of 2-5 km.
• Wide area paging can provide worldwide coverage
• Consist of a number of telephone lines, many base station transmitters and large
radio towers which simultaneously broadcast a page – Simulcasting
• Simulcast transmitters may be located within same service area or different cities
or countries

Cordless Telephone Systems
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Cordless Telephone Systems
• Full Duplex Communication system
• Provide limited range and mobility
• A portable handset is connected to a dedicated base station, which
is connected to a dedicated telephone line with a specific number
on PSTN
• Earlier cordless systems can communicate up to a few tens of
meters
• Second generation handsets can be used at outdoor locations, up
to a few hundred meters
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Cellular Telephone Systems

• Provides wireless connection to mobile phone or PSTN
• Accommodates a large number of users within a limited frequency
spectrum
• Provides high quality service compared to landline
• A large geographical area is divided into a number of smaller area
called cell
• Same frequency channels are reused in far off cells
• Handoff enables calls to proceed uninterrupted when user moves
from one cell to another

Cellular system consists of
• A mobile switching centre (MSC)
– responsible for connecting all mobiles to PSTN
• A number of base stations (BS)
– Consists of several transmitters and receivers
– Towers to support transmit and receive antennas
• A large number of mobile stations (MS)
– Contains a transceiver, an antenna and control circuit

• Base station serves as a bridge between all mobile users in the
cell and also between mobile users and the MSC
• MSC coordinates the activities of all the base stations and
connects the entire cellular system to the PSTN
• A typical MSC handles 100,000 subscribers and 5000
simultaneous conversations
• MSC does all billing and system maintenance functions

Common air interface (CAI) of mobile communication specifies four
different channels:
• Forward voice channels (FVC)
– Used for voice transmission from base station to mobile
• Reverse voice channels (RVC)
– Used for voice transmission from mobile to base station
• Forward control channels (FCC)
– Used for control signal transmission from base station to mobile
• Reverse control channels (RCC)
– Used for control signal transmission from mobile to base station

• Voice Channels
– used for voice and data traffic
– Are 95 % of total number of available channels
• Control channels
– Are used to set up a call and moving it to an unused voice channel
– Carry call initiation and service requests
– Monitored by mobiles when they don’t have a call in progress
– Broadcast all the traffic requests for all mobiles in the system
– Are 5 % of total number of channels

How a call is made from landline to mobile
• When a mobile is turned on, it scans the group of forward control
channels to determine the one with strongest signal
• Monitors that control channel until the signal drops below a usable
level, then again scans the control channels
• When a call is made from landline, MCS sends request to all base
stations
• MIN is broadcast over all the FCC as a paging message
• MS responds by identifying itself over RCC
• BS informs the MSC of the handshake

• MSC instructs the BS to move the call to unused voice channel
• BS signals MS to change frequencies to an unused forward and
reverse voice channel pair
• BS instructs MS to ring
• Once the call is in progress, MSC adjusts the transmitted power
of the mobile and changes the channel of mobile and BS to
maintain call quality as the user moves in and out of range of
each base station (handoff)

Timing diagram illustrating how a call to a mobile
user initiated by a landline subscriber is established.
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How a call is made from mobile
• When a mobile originates a call, a call initiation request is sent
on RCC by MS
• MS transmits MIN, ESN, SCM and telephone number of called
party
• BS sends this data to MSC
• MSC validates the request and makes connection to called
party through PSTN, instructs BS and MS to move to an unused
forward and reverse voice channel pair
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Timing diagram illustrating how a call initiated by a
mobile is established.
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Roaming
• Roaming allows subscribers to operate in service areas other than
the one from which service is subscribed
• When a mobile enters different city or state, it is registered as a
roamer in new service area (over FCC)
• MS reports its MIN and ESN to MSC over RCC
• MSC uses this data to request billing status from home location
register (HLR) for each roaming mobile
• Once registered, roaming mobiles are allowed to receive and place
calls from that area and billing is routed to home service provider
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Evolution of Wireless Communication
Systems

Growth of cellular telephone subscribers
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First Generation (1G) Cellular Networks
Advanced Mobile Phone Services (AMPS) and European Total Access
Communication System (ETACS)
• Based on analog technology, FM Modulation and FDD, FDMA
• Provide speech and inefficient low rate data transmission
• System control resides in MSC, which maintains all mobile related information
and controls handoff, call handling and processing, billing and fraud detection
• MSC is inter-connected with PSTN via landline trunked lines
• MSCs are connected with other MSCs for exchange of location, validation and
call signalling information

AMPS
• Uses two 25 MHz cellular bands, 824-849 MHz for reverse link and 869-894 MHz for
forward link, with 45 MHz separation between forward and reverse channels
• Each radio channel consists of two 30 kHz simplex channels separated by 45 MHZ
• Data rate 10 kbps
• Number of channels is 832
• Use large cells and omni-directional antennas
• Uses 7-cell reuse pattern with provision of sectoring and cell splitting to increase the
capacity when needed

ETACS
Similar to AMPS except
forward link
• Each radio channel consists of two 25 kHz simplex channels separated by 45 MHZ
• Data rate 8 kbps
• Number of channels is 1000
• Format of Telephone numbers are different

Second Generation (2G) Cellular Networks
• Introduced in 1990s, evolved from 1st generation
• Standards started using digital modulation and digital signal processing in the
handset and base station
• Designed and deployed for conventional mobile telephone service with higher
capacity
• Supported limited internet browsing and short message service (SMS)
• Spectrum efficiency was 3 times higher than 1G increasing the overall system
capacity

Second Generation (2G) Cellular Networks
• Global System Mobile (GSM)
– Supports 8 time slotted users in 200 kHz channels, most popular
• Interim Standard 136 (IS-136) or North American Digital Cellular (NADC)
– Supports 3 time slotted users for each 30 kHz radio channel
• Pacific Digital Cellular (PDC)
– Japanese TDMA standard
• Interim standard 95 (IS-95)
– Supports up to 64 users using CDMA on each 1.25 MHz channel

Global System Mobile (GSM)
forward link
• Uses FDD for duplexing
• uses a combination of FDMA and TDMA
• 25 MHz bands are divided into 200 kHz channels, forward and reverse channels are
separated by 45 MHz
• each channel is time shared by 8 subscribers using TDMA
• Channel data rate of 270.833 kbps using GMSK modulation
• With GSM overhead, user data rate is 24.7 kbps

GSM
• Total number of channels in 25 MHz is 125 (200 kHz channels)
• Each channel has 8 time slots, so total 1000 traffic channels
• Practically a guard band of 100 kHz is provided, so only 124 channels are
implemented
• Each time frame is of 4.615 ms, each time slot has 156.25 channel bits, 8.25 bits of
guard time, 6 start and stop bits, , each time slot of 576.92 µs

CDMA Digital Cellular Standard (IS-95)
• CDMA offers many advantages over FDMA and TDMA
• Compatible with AMPS
• Each user can use the same channel, users in adjacent cells also use the same radio
channel
• No need of frequency planning
• Each channel occupies 1.25 MHz spectrum
• User data rate changes in real time, depending on voice activity and requirements in
the network

IS-95
• Uses different modulation and spreading for forward and reverse links
• On forward link, base station simultaneously transmits the user data for all users in
the cell by using a different spreading code
• A pilot code is also transmitted simultaneously at a higher power level, allowing all
the mobiles to use coherent carrier detection
• On the reverse link, all mobiles respond in an asynchronous fashion and have a
constant signal level due to power control

IS-95
forward link
• Forward and reverse channel pair is separated by 45 MHz
• Maximum user data rate is 9.6 kbps, chip rate is 1.2288 Mcps (a spreading factor of
128)
• Spreading process is different on forward and reverse links
• 64 orthogonal walsh codes are used

Worldwide subscriber base as a function of cellular
technology in late 2001
.
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Poonam Singh EC Dept, NIT Rourkela
Key specifications for 2G
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Various upgrade paths for 2G technologies.
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2.5G Cellular Networks
• High Speed Circuit Switched Data (HSCSD)
• General Packet Radio Service (GPRS)
• Enhanced Data Rates for GSM Evolution (EDGE)

High Speed Circuit Switched Data (HSCSD)
• HSCSD is a circuit switched technique, allows each user to use consecutive time slots
to get higher data rates
• Relaxes error control coding algorithms and increases data rates from 9.6 to 14.4
kbps, by using up to 4 consecutive time slots, data rate may be 57.6 kbps for
individual users
• Ideal for internet access or real time interactive web sessions
• Only required the service provider to implement a software change at existing GSM
base stations

General Packet Radio Service (GPRS)
• Packet based data network
• Well suited for non real time internet usage e.g mails, fax, asymmetric web browsing
• Supports multi user network sharing of radio channels and time slots unlike HSCSD
where dedicated channels and time slots are used
• GPRS can support many more users than HSCSD, but in a bursty manner
• Provides a packet network on dedicated GSM or IS-136 channels
• Retains the original modulation formats, but uses a redefined air interface to handle
packet data access

Enhanced Data Rates for GSM Evolution (EDGE)
• More advanced upgrade to GSM standard
• Requires addition of new hardware and software at existing base station
• New digital modulation format, 8-PSK is used in addition to GMSK modulation
• Supports multiple modulation and coding schemes (MCS), with nine different
air interface formats
• Each user connection adaptively determines the best MCS setting for
particular radio propagation conditions and user data access requirements

IS-95B
• Provides high speed packet and circuit switched data access on a common CDMA
radio channel by dedicating multiple orthogonal user channels for specific users
• In IS-95, each radio channel supports up to 64 different user channels at a data rate
of 9.6 kbps, was improved to 14.4 kbps in IS-95A
• IS-95B supports user access of 8 different Walsh codes simultaneously providing a
data rate of 115.2 kbps per user
• However, practically only 64 kbps data rate is available to a single user
• IS-95B uses hard hand-off, whereas IS-95 used soft hand-off

3rd Generation Wireless Networks
New Features
• Multi-megabit internet access
• Communication using voice over internet protocol (VoIP)
• Voice activated calls
• Improved network capacity
• Ubiquitous “always-ON” access
• Supports live music, interactive web sessions, simultaneous voice and data access
with multiple users using single mobile

3rd Generation Wireless Networks
International Telecommunications Union (ITU) formulated a plan to implement a
global frequency band in 2000 MHz range that would support a single
ubiquitous wireless communication standard for all countries of the world.
This plan called International Mobile Telephone 2000 (IMT-2000) resulted in 3
different standards:
• Wideband CDMA (W-CDMA) or Universal Mobile Telecommunication Service
(UMTS)
• cdma2000
• TD-SCDMA

Wideband CDMA (W-CDMA) or UMTS
• Backward compatible with GSM, IS-136, PDC and all 2.5G TDMA technologies
• Packet based wireless service
• Supports packet data rates up to 2.048 Mbps
• Supports high quality data, multimedia, streaming audio and video and broadcast
type services
• Provides public and private network features, video conferencing and virtual home
entertainment (VHE)

cdma2000
• Provides a seamless high data rate upgrade path for 2G and 2.5G CDMA technology
• Uses channel bandwidth of 1.25 MHz per radio channel, which is same as IS-95, IS-
95A or IS-95B (2G and 2.5G standards)
• No additional RF equipment is needed to enhance performance, changes are made
in software or in baseband hardware
• Three variations of the standard are proposed:
– cdma2000 1 x RTT (Radio Transmission Technology)
– cdma2000 1 x EV
– cdma2000 3 x RTT

cdma2000 1 x RTT
• cdma2000 1 x RTT (Radio Transmission Technology)
– Implies that a single 1.25 MHz channel is used
– supports data rates up to 144 kbps per user
– Supports twice as many voice users as 2G CDMA standard
– Longer lasting battery life
– Supports both TDD (cordless) and FDD (mobile radio) applications
– Uses rapidly adaptable baseband signalling rates and chipping rates for each user
and multi-level keying

cdma2000 1 x EV
• Evolutionary advancement for CDMA originally developed by Qualcomm
• High data rate (HDR) packet standard to be overlaid upon existing IS-95, IS-95B and
cdma2000 networks
• Was modified to be compatible with W-CDMA also
• Provides option of installing radio channels with data only (cdma2000 1xEV-DO) or
with data and voice (1xEV-DV)
• Uses 1.25 MHz channels to provide high speed packet data access (greater than 2.4
Mbps for cdma2000 1xEV-DO)
• cdma2000 1xEV-DV can offer data rates up to 144 kbps with twice as many voice
channels as IS-95B

cdma2000 3 x RTT
• Uses 3 adjacent 1.25 MHz radio channels together for increased bandwidth to
provide high data rates
• Can be used as 3 individual 1.25 MHz channels (no new hardware required) or a
single 3.75 MHz channel (new hardware is required at base station)
• Much more seamless and less expensive upgrade path as compared to W-CDMA

Time Division - Synchronous CDMA (TD-SCDMA)
• A time division duplex (TDD) version of UMTS – developed and used in China
• was adopted by 3GPP and included in the 3GPP standards
• TD-SCDMA offers the advantages of a TDD system, and many new
technologies including joint detection, adaptive antennas, and dynamic
channel allocation.
• TD-SCDMA was never deployed outside China
• It promoted the advantages of TDD systems and enabled 4G LTE push
forwards the TDD versions of 4G LTE.

Advantages
• Balances between uplink and downlink to accommodate the different levels
of data transfer.
• Uses unpaired spectrum, spectrum efficiency is more
• It does not require expensive duplexers in the handsets to enable
simultaneous transmission on the uplink and downlink
• Transmit / receive switching times must be accommodated and can reduce
the efficiency of the system.
• TD-SCDMA uses the same RAN as that used for UMTS, thereby simplifying
multi-system designs.
• It has been adopted as the low chip rate (LCR) version of the 3GPP TDD
standard.

TD-SCDMA SPECIFICATION SUMMARY
TD-SCDMA CHARACTERISTIC FIGURE
Bandwidth 1.6 MHz
Chip rate per carrier 1.28 Mcps
Frame Rate 10ms
Spectrum spreading mode DS SF=1/2/4/8/16
Modulation QPSK / 8PSK / 16QAM
Channel coding Convolutional codes: R=1/2,1/3 Turbo
implemented
Interleaving 10/20/40/80 ms
Frame structure Super frame 720ms,Radio frame 10ms
Subframe 5 ms
Uplink synchronisation 1/2 chip
Number of voice channels per carrier 48
Spectrum Efficiency 25 Erl./MHz
Total transmission rate provided by
each carrier
1.971Mbps

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Fourth Generation (4G) Wireless Networks
• Fourth Generation (4G) mobile phones provide broadband cellular network services
• It provides an all IP packet switched network for transmission of voice, data, signals
and multimedia.
• It aims to provide high quality uninterrupted services to any location at any time.
• 4G networks should have peak data rates of 100 Mbps for highly mobile stations and
1 Gbps for low mobility stations.
• They provide smooth handoffs across heterogeneous network areas.

4G
4G comes in two main categories
• Long – Term Evolution (LTE)− is an extension of the 3G technology, also called 3GPP
LTE (3rd Generation Parternship Project Long Term Evolution)
• Worldwide Interoperability for Microwave Access (WIMAX) is a mobile wireless
broadband access (MWBA) standard

Long – Term Evolution (LTE)
• Long – term evolution or LTE is an extension of the 3G technology.
• It is a standard for high-speed mobile communication, based upon GSM/EDGE
and UMTS/HSPA technologies.
• The peak data rate for download is 100 Mbps and upload is 50 Mbps.
• The LTE Advanced meets the specifications of IMT-Advanced standard for 4G
technology.
• Its peak data rates are 1000 Mbps for downlink and 500 Mbps for uplink.

Worldwide Interoperability for Microwave Access
(WIMAX)
• Worldwide Interoperability for Microwave Access (WIMAX) is a mobile wireless
broadband access (MWBA) standard
• It offers peak data rates of 128 Mbps for downlink and 56 Mbps for uplink over 20
MHz wide channels.
• The latest version of WIMAX is not compatible to the earlier versions and instead is
compatible with LTE.

Key features of 4G system
• Much higher data rate up to 1Gbps
• Enhanced security and mobility
• Reduced latency for mission critical applications
• High definition video streaming and gaming
• Voice over LTE network VoLTE (use IP packets for voice)
Disadvantages
• Expensive hardware and infrastructure
• Costly spectrum (most countries, frequency bands are too expensive)
• High end mobile devices compatible with 4G technology required, which is costly
• Wide deployment and upgrade is time consuming

5G Communications
• Next major phase of mobile telecommunication & wireless system
• More capacity, more faster & reliable than 4G
• High-quality streaming media many hours per day on the mobile
devices, also when out of reach of wi-fi hotspots
• Improved support of machine to machine communication, also
known as the Internet of things (IoT)
• Lower cost, lower battery consumption, and lower latency than
previous generations
• Far better levels of connectivity and coverage.
18-08-2022 Prof. Poonam Singh EC Dept. NIT Rourkela 81

5G requirements
PARAMETER SUGGESTED PERFORMANCE
Peak data rate At least 20 Gbps downlink and 10 Gbps uplink per mobile
base station. This represents a 20 fold increase on the
downlink over LTE.
5G connection density At least 1 million connected devices per square kilometre
(to enable IoT support).
5G mobility 0 km/h to "500 km/h high speed vehicular" access.
5G energy efficiency The 5G spec calls for radio interfaces that are energy
efficient when under load, but also drop into a low energy
mode quickly when not in use.
5G spectral efficiency 30 bits/Hz downlink and 15 bits/Hz uplink. This assumes
8x4 MIMO (8 spatial layers down, 4 spatial layers up).
5G real-world data rate The spec "only" calls for a per-user download speed of
100 Mbps and upload speed of 50 Mbps.
5G latency 5G networks should offer users a maximum latency of just
4 ms (compared to 20 ms for LTE).

5G Technologies
New technologies and techniques to enable 5G to provide more
flexible and dynamic services:
• Millimetre-Wave communications
• New Waveforms
• Multiple Access Schemes
• Massive MIMO with beamsteering
• Dense networks
These are a few of the main techniques being developed and
discussed for use within 5G.

Advantages of 5G
• Data rate of 1 Gbps or higher
• Globally accessible
• Dynamic information access
• Low cost
• High resolution and bi-directional large bandwidth shaping.
• More effective and efficient.
• A huge broadcasting data (in Gigabit), which will support more than 60,000
connections.
• Easily manageable with the previous generations.
• Support heterogeneous services, all networks on one platform.
• Provide uniform, uninterrupted, and consistent connectivity across the world.

Disadvantages
• Technology is still under process and research on its viability is going on.
• The speed, this technology is claiming seems difficult to achieve (in future,
it might be) because of the incompetent technological support in most
parts of the world.
• Many of the old devices would not be competent to 5G, hence, all of
them need to be replaced with new one — expensive deal.
• Developing infrastructure needs high cost.
• Security and privacy issue yet to be solved.

Applications of 5G
• It will make unified global standard for all.
• Network availability will be everywhere and will facilitate people to use
their computer and such kind of mobile devices anywhere anytime.
• Because of the IPv6 technology, visiting care of mobile IP address will be
assigned as per the connected network and geographical position.
• Its application will make world real Wi Fi zone.
• Its cognitive radio technology will facilitate different version of radio
technologies to share the same spectrum efficiently.
• Its application will facilitate people to avail radio signal at higher altitude
as well.

Comparison of 1G to 5G technology
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6G Communications
• 6G networks are expected to exhibit even more heterogeneity and are likely
to support applications beyond current mobile use scenarios, such
as virtual and augmented reality (VR/AR), ubiquitous instant communications,
pervasive intelligence and the Internet of Things (IoT).
• The mobile network operators will adopt flexible decentralized business
models for 6G, with local spectrum licensing, spectrum sharing, infrastructure
sharing, and intelligent automated management underpinned by mobile edge
computing, artificial intelligence (AI), short-packet communication
and blockchain technologies.

Features of 6G
• Much Higher Data Rate.
• Much Lower Latency.
• Network Reliability and Accuracy.
• Emphasis on Energy-Efficiency.
• Machines as Primary Users.
• AI-Driven Wireless Communication Tools.
• Personalized Network Experience.

Features and challenges of 6G
• AI is included in many of 6G applications
• Human-centric mobile communications will be most important application of 6G.
• High security, secrecy and privacy should be key features of 6G and should be given
particular attention by the wireless research community.
• Frequencies from 100 GHz to 3 THz are promising bands for the next generation of
wireless communication systems because of the wide range of unused and
unexplored spectrum.
• One of the biggest challenges in supporting the required high transmission speeds
will be the limitation of energy/power consumption and associated heat
development in the electronic circuits to acceptable proportions.

WIRELESS LOCAL AREA NETWORK (WLAN)
• A wireless LAN (WLAN) is a wireless computer network that links two or more
devices using wireless communication to form a local area network (LAN) within a
limited area such as a home, school, computer laboratory, campus, or office
building.
• Also known as Wireless Fidelity (Wi-Fi)
• WLANs use radio, infrared and microwave transmission to transmit data from one
point to another without cables.
• Therefore WLAN offers way to build a Local Area Network without cables.
• WLAN can then be attached to an already existing larger network, the internet for
example.

WLAN
• WLAN includes an access point (AP) which is used to connect to the
internet.
• AP sends and receives radio frequency signal to the connected devices.
• In 1990 WLAN installation was expensive and was only deployed where the
wired connection was not possible.
• In the late 1990s, cost to implement WLAN decreased because of using
IEEE 802.11 standard.
• It works with a bandwidth of 2.4 GHZ (802.11b) or 5 GHZ (802.11 a).
• The devices which WLAN connects are also called clients.

WLAN
• WLAN gives a high data transfer rate.
• It uses star topology in which all nodes send/receive data through access
points.
• It works better in homes and offices, especially in offices no extra cables are
required and arranging a meeting is also easy.
• It has a data transfer rate of 1-10 Mbps.
• Wireless LAN uses security which includes WEP (Wired Equivalent Privacy) or
WPA (Wireless Protected Access).
• It also uses infrared technology if required.

WLAN Standards
• IEEE 802.11 is a working group of the Institute of Electrical and Electronics Engineers IEEE
802 standards committee which specifies wireless network standards.
• Wireless LAN is a set of low tier, terrestrial, network technologies for data communication.
• It specifies the set of media access control (MAC) and physical layer (PHY) protocols for
implementing WLAN communication.
• The WLAN standards operates on the 2.4 GHz and 5 GHz Industrial, Science and Medical
(ISM) frequency bands.
• It is specified by the IEEE 802.11 standard and it comes in many different variations like IEEE
802.11 a/b/g/n.
• The application of WLAN has been most visible in the consumer market where most
portable computers support at least one of the variations.

Overview of the IEEE 802.11 Wireless LAN standard.
18-08-2022 95

Specifications in the IEEE 802.11 family
• IEEE 802.11
– This pertains to wireless LANs and provides 1 or 2 Mbps transmission in the 2.4
GHz band using either frequency-hopping spread spectrum (FHSS) or direct-
sequence spread spectrum (DSSS).
• IEEE 802.11b
– The 802.11b is a high data rate Wi-Fi, it is an extension to 802.11 that yields a
data rate as fast as 11 Mbps transmission (with a fall-back to 5.5, 2, and 1 Mbps
depending on strength of signal) in the 2.4-GHz band.
– The 802.11b specification uses only DSSS.
– 802.11b was an amendment to the original 802.11 standard added in 1999 to
permit wireless functionality to be analogous to hard-wired Ethernet
connections.

IEEE 802.11 standards
IEEE 802.11a
• This is an extension to 802.11 that goes as fast as 54 Mbps in the 5 GHz band.
• 802.11a employs the orthogonal frequency division multiplexing (OFDM) encoding
scheme
• 802.11a uses 5 GHz frequency band which is less crowded and hence has relatively
smaller interference problem.
• 802.11a supports up to 54 Mbps of bandwidth, which is much faster than the 11
Mbps bandwidth provided by 802.11b standard devices.
• 802.11a offers as many as 12 non-overlapping channels.

IEEE 802.11g
Advantages:
• Higher bandwidth at 54 Mbps,
• Cheaper than 802.11a, and costs close to 802.11b.
• 802.11g uses 2.4 GHz frequency band, just like 802.11b.
• Backward compatible with 802.11b standard
The main disadvantages are:
• Higher cost compared to 802.11b (at least by 50%)
• Not widely supported by the client machines such as laptops, and PDAs.
• Devices compatible with both 802.11a and 802.11b are needed considering future
expansion and compatibility in diverse network environments.

IEEE 802.11n
– It is build upon previous 802.11 standards by adding multiple-
input multiple-output (MIMO).
– The additional transmitter and receiver antennas allow for increased
data throughput through spatial multiplexing and increased range by
exploiting the spatial diversity through coding schemes like Alamouti
coding.
– The real speed would be 100 Mbit/s (even 250 Mbit/s in PHY level),
and so up to 4-5 times faster than 802.11g.

Technical comparison between the three major WiFi standards
Feature WiFi (802.11b) WiFi (802.11a/g)
PrimaryApplication Wireless LAN Wireless LAN
Frequency Band 2.4 GHz ISM 2.4 GHz ISM (g)
5 GHz U-NII (a)
Channel Bandwidth 25 MHz 20 MHz
Half/Full Duplex Half Half
Radio Technology Direct Sequence
Spread Spectrum
OFDM
(64-channels)
Bandwidth <=0.44 bps/Hz ≤=2.7 bps/Hz
Efficiency
Modulation QPSK BPSK, QPSK, 16-, 64-QAM
FEC None Convolutional Code
Encryption Optional- RC4m (AES in 802.11i) Optional- RC4(AES in 802.11i)
Mobility In development In development
Mesh Vendor Proprietary Vendor Proprietary
Access Protocol CSMA/CA CSMA/CA

Wireless Personal Area Network (WPAN)
• A wireless personal area network (WPAN) is a PAN carried over a low-powered,
short-distance wireless network technology such as IrDA, Wireless USB, Bluetooth or
ZigBee.
• The reach of a WPAN varies from a few centimetres to a few meters.
• Unlike WLAN, a connection made through a WPAN involves little or no infrastructure
or direct connectivity to the world outside the link.
• This allows small, power-efficient, inexpensive solutions to be implemented for a
wide range of devices.

Wireless Personal Area Network (WPAN)
Features
• Short-range communication
• Low power consumption
• Low cost
• Small personal networks
• Communication of devices within a personal space

WPAN standard-IEEE 802.15
• IEEE 802.15 specifies wireless personal area network (WPAN) standards.
• Many standards are available for personal area networks.
• Each standard has strengths and weaknesses, making it suitable for specific
application scenarios.
• In some cases, more than one technology will be able to perform a required
task, hence nontechnical factors such as cost and availability will factor into
the decision as to which technology is more appropriate.

WPAN standards
• Three wireless standards are leading the way for WPANs: IrDA, Bluetooth, and
ZigBee.
• Each of these standards enables users to connect a variety of devices without
having to buy, carry, or connect cables.
• They also provide a way to establish adhoc networks among the abundance
of mobile devices on the market.
• Unlike IR, Bluetooth does not require a line of sight between devices to be
effective. It is able to communicate through physical barriers, typically with a
range of 10 meters. With power amplifiers, 100 meters is possible.

IEEE 802.15.1-Bluetooth
• Bluetooth is a standard for enabling wireless communication between mobile
computers, mobile phones, and portable handheld devices.
• The IEEE 802.15. 1 standard is used for the Bluetooth wireless communication
technology.
• Bluetooth is a low tier, adhoc, terrestrial, wireless standard for short
range communication.
• It is designed for small and low cost devices with low power consumption.

Infrared Data Association (IrDA)
• IrDA is an international organization that creates and promotes interoperable, low-
cost infrared data connection standards.
• IrDA has a set of protocols to support a broad range of appliances, computing, and
communication devices.
• These protocols are typically aimed at providing high-speed, short-range, line-of-
sight, and point-to-point wireless data transfer.
• IrDA protocols use IrDA DATA as the data delivery mechanism, and IrDA CONTROL as
the controlling mechanism.

IrDA features
• Communication range of up to 1 meter, although a distance of 2 meters can
often be reached.
• A low-power option for communication up to 20 cm. This requires 10 times
less power than the full-power implementation.
• Bidirectional communication.
• Data transmission from 9600 bps to a maximum speed of 4 Mbps.

IEEE 802.15.4 - ZigBee
• Zigbee is a wireless technology developed as an open global standard to address the
unique needs of low-cost, low-power wireless IoT networks.
• The Zigbee standard operates on the IEEE 802.15.4 protocol
• The protocol allows devices to communicate in a variety of network topologies and
can have battery life lasting several years.
• ZigBee is a low tier, ad hoc, terrestrial, wireless standard in some ways similar to
Bluetooth.
• The IEEE 802.15.4 standard is commonly known as ZigBee, but ZigBee has some
features in addition to those of 802.15.4.
• It operates in the 868 MHz, 915 MHz and 2.4 GHz ISM bands.

Wireless Body Area Network (WBAN)
• A Wireless Body Area Network (WBAN) is a special purpose sensor network
designed to operate autonomously to connect various medical sensors and
appliances, located inside and outside of a human body.
• A body area network (BAN), also referred to as a wireless body area
network (WBAN) or a body sensor network (BSN) or a medical body area
network (MBAN), is a wireless network of wearable computing devices.
• BAN devices may be embedded inside the body as implants, may be surface-
mounted on the body in a fixed position, or may be accompanied devices which
humans can carry in different positions, such as in clothes pockets, by hand, or in
various bags.

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