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WORKSHOP ON EMERGING TRENDS IN TECHNOLOGIES FOR
WLANS, WPANS, HANS, UWBS, MOBILE SATELLITE PHONE
SERVICES & 4G CELLULAR SYSTEMS
ORGANISED JOINTLYBY
BHARAT INSTITUTE OF ENGG., & TECHNOLOGYMANGANPALLY, RANGAREDDY DISTRICT
AND
DEFENCE RESEARCH & DEVELOPMENT ORGANISATION
DLRL-ELSEC Hyderabad Ministry of Defence
Evolution of wireless technologies
ByProf.G.Kumaraswamy Rao
HOD ECE Dept. BIET
(Former Director DLRL)
Date: 29th August 2011 Venue: ELSEC-DLRL
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What is Communication?
- Exchange of i) Voice ii) Data iii) Video from one pointto another .
- Medium for communicationa) Wired - i) Copper (Cable, TP)
ii) Fibre Optics
b) Wireless - i) R.F.
ii) I.R.
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WIRELESS SIGNIFICANCE
Wireless communication technologyhas a huge impact onmost of developed world and a large number of developingcountries.
Wireless Communication is affecting almost every aspect ofour daily lives.
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What is Wireless Communication??
All types of devices that are not connected by a wire butstill interface with each other
Examples of Wireless:1. Garage door opener
2. Television remote control
3. Pager
4. Cell phone
5. Cordless phone
Another meaning of Wireless:- transmission of data without wires
Ex: 1. e mail messages
2. Spread sheets
3. Telephone voice messages
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USES OF WIRELESS TECHNOLOGIES
Voice/Data can be sent or received.
Browse the Internet.
Access corporate databases from any location in the
world.Devices like PCs, digital cameras, laser printers,
scanners,
and other office equipment can communicate with each
otherRefrigerators, A/Cs, heaters, microwave ovens, water
heaters or any other household item can be controlledremotely by using wireless remotely.
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WIRELESS COMMUNICATIONS:TRENDS & CHALLENGES
High Data Rate Services
High spectral efficiency
Advancement to 3G and beyond communication to
improve data rate.Ex. i) ECDMA based DS-CDMA direct spread with FDD
ii) CDMA 2000 multi carrier CDMA
iii) TDD-CDMA Time Division Duplex
MIMO Multiple Input Multiple OutputUWB - Ultra wideband cross-layer design
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WIRELESS COMMUNICATION BASICS
Quality of Digital transmission:
1. Speed or bits/second
2. Bit Error Rate BER
BER is the percentage of bits are in error by the time itreaches the receiver
Good transmission ensures 0.0001 to 0.0002 percent
(1 to 2 bits in 106
bits)
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LAWS OF COMMUNICATION
NQUIST RATE (1928)fp 2B where fp = Number of independent pulses per
sec.B = Bandwidth HZ
HARTLEYS LAWR 2B Log2 (M)
where R = Number of bits per sec.M = Number of signal levels in a symbol
SHANNONS THEOREMR B Log2 (1+SNR)
where SNR = Signal to Noise Ratio
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EXAMPLE:
i) Channel Bandwidth = 1 MHZ
ii) SNR = 63
Max. channel capacity = C = B log2 (P+SNR)= 106 log2 (1+63) = 6MBps
Using Nquist to get Signal
Levels
C = 2B log2 2n
6 x 106 = 2x1x106xlog22n
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TYPES OF NETWORKS
LAN (Local Area Network) 500 Mts MAN (Metropolitan Area Network) 50 KM WAN (Wide Area Network) > 50 KMs to 250 KMs.
NETWORK TOPOLOGIESi. Bus topologyii. Star topologyiii. Ring topologyiv. Mesh topology
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NETWORK SWITCHING
i) CIRCUIT SWITCHING:
SWITCHING OFFICE
TELEPHONE
TELEPHONE
There is a physical connection between transmitter & receiver until the call isterminated
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ii) PACKET SWITCHING
Bursty data transmission.
Individual packets forwarded need not take the same path.Congestion/Collission of packets takes place.
iii) MESSAGE SWITCHING
Ex: Telegraph Message
1 2
Packet 1
Packet 1
Packet 2
Packet 2
Packet 2
Station Station
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MULTIPLE ACCESS
To share the limited number of channels simultaneously by
many mobile users, multiple access techniques are used.
1) Frequency Division Multiple Access (FDMA)
2) Time Division Multiple Access (TDMA)
3) Code Division Multiple Access (CDMA)
FDMA
- Individual channels are assigned to users.
- FDD Frequency Division Duplex.- Two (2) distinct frequencies are allotted for every user
i) forward channel ii) reverse channel called FDD.
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TIME DIVISION MULTIPLE ACCESS
TDMA:- Time slots are allotted to each user.
- All users use the same frequency.
- Frequency Duplexers not required.- Time synchronization required.
- Each Frame has preamble, information and trial bits.
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SPREAD SPECTRUM MULTIPLE ACCESS(SSMA)
Spreads the information over a bandwidth severalorders of magnitude wider than the information.
Spreading sequence (code) should be known torecipient
Types of SSMA:
i) Frequencyhopping
ii) Direct Sequence also called CDMA.
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WHY WIRELESS?
1. Mobility: Freedom to move without tethered by wires
Ex: Police Officers, travelling persons, inventory clerks2. Easier & Less Expensive:
- Cabling in existing building difficult, cumbersome &
expensive
- Cabling in historical bldgs. spoils the aesthetic valueof the premises
- Installation time consumed is more and disturbs existingwork.
3. Increased reliability
- Cable breakages, loose connection in connectors etc.
avoided.
4. Disaster events (Accidents, fires, tornadoes, tsunamies)
- Quickly devices can be configured on adhoc basis.
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WIRELESS APPLICATIONS
i) Education: E class room
ii) Home Entertainment: Control of lights, air-conditioning,
refrigerators, washing machines, PCs, scanners, printers
etc.
iii) Health Care: Consultations with specialists doctors.
iv) Government: Monitor municipal vehicles, despatch of
work crews in emergencies.
v) Military: Soldiers at any place can access data bases,
access internet.
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vi) Office Environment: Every employee have access to office
database.
- Expensive cabling is avoided.
- Adhoc office environment can be created in a very
short period.
- Costly resources like colour printers, scanners etc.
can be shared.
vii) Warehouse Environment: Inventory of the goods
maintained.
- Update of stock and shortage.viii) Industrial Control: Various places in a large workshop
where wires cannot be installed, connected by wireless.
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DISADVANTAGES OF WIRELESS
Radio Signal Interferencesi. from signals from own system
ii. from signals of other deviceiii. microwave ovens
iv. elevator motors
v. heavy electrical equipment
Bandwidth limitations in the spectrum Security is low since signals are transmitted in air
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WIRELESS TYPES
Types of Wireless:
i) Fixed - Ex: Microwave Towers
ii) Low Mobility Pedestrian
iii) High Mobility Vehicle at 150 KMPH iv) Satellites
Types of Wireless:
i) Personal Area Network (PAN)
ii) Wireless LAN a) Low rate b) High rate
iii) Wireless MAN
iv) Wide Area a) Wide Area LAN
b) Cellular
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WIRELESS TECHNOLOGIES
i. Blue toothii. Ultra wide bandiii. Satelliteiv. Cellularv. Wireless LANvi. Fixed broad band
vii. Wireless WAN
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WIRELESS DATA COMMUNICATION TECHNOLOGIES
Wireless Technology Transmission Distance Speed
RFID 2.5 cms to 100 mts a few KBPS
Blue Tooth 10 mts 1 mbps
UWB 50 mts 100 mbps
WLAN 802.11b
WLAN 802.11g
110 mts
90 mts
11 mbps
54 mbps
WMAN 802.16 Wi Max 56 Kms 75 mbps
2G Digital Cellular
2.5G Digital Cellular
3.5G Digital Cellular
Nation wide
Nation wide
Nation wide
-
384 kbps
2 mbps
Satellite World wide 250 msecs delay
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VISION OF AN IDEAL WIRELESSNETWORK/DEVICE - 1
REAL-TIME VIDEO:
- Data rates high
- Delay constraint like in voice
TECHNICAL ISSUES:
- Devices small, light weight, hand held, cheap, multiple
mode to support i) Voice ii) Image iii) Text iv) Video
data
- Battery small, Recharge interval large
- Place all power intensive software on fixed sites
GEO LOCATION:
- Locate user any where in the globe in short time
INTER CONNECTIVITY:
- With PSTN, satellite network, submarine cable, internet.
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VISION OF AN IDEAL WIRELESSNETWORK/DEVICE - 2
COVERAGE:
i) In building ii) Campus iii) City iv) Regional v) Global
SUPPORT:
- Voice Systems: - Low Data Rate 20 KBPS
- BER < 10-3
- Delay < 100 ms
- Data Systems: - Data Rates 1-100 MBPS
- BER < 10-8 Retransmission of
Error Data
- No restriction on delay
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VISION OF AN IDEAL WIRELESSNETWORK/DEVICE - 3
RADIO SPECTRUM:- Frequency spectrum is scarce resource, so very
expensive
- Licenses to use spectrum are auctioned (GSM gave
4,50,000 crores).- Use of high frequency give more bandwidth.
Equipment Cost more and range limited because of
attenuation and puts loss.
MOBILITY:
- Terminals moving at 200 KMPH should be located and interfaced.
- Without subscriber knowing, seamless transfer from one cell to
another or standard.
SECURITY:
- Concern area for wireless proper encryption.
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CELLULAR NETWORKS
Network is built around a low power transmitters.
Each cell has a small geographical area handlesnumber of users.
Many transmitter towers are spread throughout thegeographical area.
Same R.F. Channels can be used by another towerlocated a few kilometers away to avoid interference.
This concept maximizes the use of limited bandwidth.
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MTSOPSTN
B.S.
BaseStation
MTSO Mobile Telephone
Switching Office
PSTN-PublicSwitchedTelephone
Network
CELLULAR NETWORK
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1G FIRST GENERATION CELLULARNETWORK
First Cellular System deployed in Norway - 1981.
Voice transmission.
Analog Modulation FM-FDMA.
Advanced Mobile Phone System (AMPS) in NorthAmerica 1983
7 cell reuse.
25 MHZ band in uplink from 824-849 MHZ.
832 channels. Channel spacing 30 KHZ.
Circuit switched technology.
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2G CELLULAR NETWORK
Uses TDMA (GSM) or CDMA
Supports roaming between network operators/differentcountries.
Supports circuit-switched voice communication.
Supports mobile data.Supports internet services.
Standards IS-136(USA) TDMA; IS-95(USA+Korea)CDMA; GSM TDM (Europe+India)
Data Rates 9.6 KBPS.GSM supports 8 time slots (users). Each slot has 200
KHZ.
GSM 935-960 MHZ & 890-915 MHZ.
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2.5G CELLULAR NETWORKS (GPRS)
Standards 1. General Packet Radio Services (GPRS).
Packet Switched Network.
Data Rate 21.4 KBPS.
If all 8 time slots are used consecutively, data rate 171.2KBPS.
Each user provide their own error correction scheme.
Supports circuit switched voice transmission.
Supports packet switched data transmission.
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2.5G CELLULAR NETWORKS (EDGE & HSCD)
Standards 2. Enhanced Data Rates for GSM Evolution(EDGE).
Uses Octal phase shift keying 8-PSK.
Data rate 547.2 KBPS. BUT RESTRICTED TO 384 KBPS.
Standard 3. HSCD High Speed Circuit Switched Data.
Allows a single mobile user to use consecutive time slots.
Original 2.5G allows 21.4 KBPS Increases to 57.6KBPS.
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3G CELLULAR NETWORKS
2G Systems support data over voice paths. Speeds arelow 9.6 KBPS to 14.4 KBPS.
1980 Planning for 3 G started.
Goal of 3G : i) Merge all standards into one.
ii) Internet Access. 3G phones require quintuple mode
i) 800/900 MHZ band
ii) 1.7 to 1.9 GHZ band
iii) 2.5 to 2.69 GHZ band
Consensus is for
i) 5 different Radio standards
ii) 3 different frequency bands.
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3G CELLULAR NETWORKS
NECESSITY FOR 3G- All 2G Systems are Voice Centric.
- GSM supports SMS, Text messages upto 160
characters
- 2G Data Speeds low 9.6 or 14.4 KBPS.- Planning for 3G started 1980.
GOAL OF 3G
- Worldwide Roaming Connectivity instead multimode
mobile.- Increase of Data Rate 144 KBPS for fast moving
vehicles
- 2 MBPS for stationary mobile.
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3G STANDARDS
PRESENT STANDARDS
Frequency: i) 800/900MHZ ii) 1.7 to 1.9GHZ iii) 2.5 to2.69 GHZ.
GSM USERS: i) W-CDMA ii) TD-SCDMA (CHINA)
CDMA USERS CDMA 2000
UMTS Universal Mobile Communication System group.
Backward compatibility with GSM, IS-136 & PDC TDMA
Support 2.048 MBPS.
Spectrum 5 MHZ.
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3G-W-CDMA
UMTS Universal Mobile Communication System group.
Backward compatibility with GSM, IS-136 & PDC TDMA.
Support 2.048 MBPS.
Spectrum 5 MHZ.
Uses Direct Sequence Spread Spectrum DS-SS.
High quality data, multimedia, streaming video, audio,
broadcast services. 6 times increase in spectral efficiency over GSM.
Cell phone Tri-mode i) 2G TDMA ii) EDGE iii) W-CDMA
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3G-CDMA 2000
Seamless support to 2 and 2.5G CDMA users (IS-95,IS-95A, IS-95B).
3G PP2 working developed this technology.
Each channel bandwidth 1.25 MHZ.
CDMA 2000 1 x means single carrier is used.
CDMA 2000 3 x RTT uses 3 adjacent 1.25 MHZ channels.
Adjacent channels combined to get super channel 3.75MHZ.
Less expensive upgrade than W-CDMA technology.
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3G TD-SCDMA
Most popular in China.
Time Division Synchronous Code Division MultipleAccess.
Radio channel is 1.6 MHZ.
5 M secs. Frame divided into 7 time slots.
Number of slots allotted to user depending on data rate.
For subscriber downloading data, require more numberof time slots than reverse channel.
SCDMA is more efficient.
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MIGRATING TO 4G
GOAL:
Integrate every wireless standard.
Seamless adaptability to multiple wireless standards.
Auto reconfiguration by downloading configurationsoftware.
Smooth handoff between cells of different standards.
Ubiquitous available at any time and at any place.
Service transparency in billing.
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DIFFERENT STANDARDS IN MOBILECOMMUNICATIONS
Technology 1G 2G 2.5G 3G 4G
Year of
idea
1970 1980 1985 1990 2000
Implementation 1984 1991 1999 2002 2012??
Service AnalogVoice
DigitalVoice
Packetized Broadband2mbps
IP
oriented
Multiple Access FDMA TDMACDMA
TDMACDMA
CDMA -
Data Speed 1.9KBPS
14.4 kbps 384 KBPS 2 MBPS 200 MBPS
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SATELLITE COMMUNICATIONS
Satellites LEO 2000 KMS altitude.
MEO 9000 KMS altitude.
GEO 35786 KMS altitude.
Satellite provide communication to remote areas wherecellular telephones or landlines becomes uneconomical.
Covers large area because of height advantage.
Provides high availability, reliability and quality etc.
Satellites are used for i) Broadcast of entertainment TVchannels ii) Digital Radio iii) Telecommunication.
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SATELLITE EARTH STATION
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SATELLITE NETWORK
Mobile Satellite services
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Mobile Satellite services
Why LEOs/MEOs ARE preferred to GEO?
*GEO propagation is 0.25 sec. not attractivefor voice
*Propagation Loss {4R/}2 So GEO not preferred
*LEO are about 1850 Kms. Altitude*Operating Frequency 2 GHz. (Low preferred because of
{4R/}2
*In present technology 2400 Bps enough for toll qualityvoice communication
*Omni antenna required for hand held mobile phone
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Characteristics of MSS
Low delay in voice transmission
LEO have orbital eriods of 1.5 to 10 hours
High inclination angles appear overheadtwice a day
3 basic types
i) Non voice little LEOS
ii) Full service LEOSiii) Broad band LEOS
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LITTLE LEOS
Support 100 to 300 Bps
Frequency below 1GHs
Store and forward box in sky
Ex: ORB comm.
-Messagimg ,Emergency
-36 satellites
-VHF -148- 150.5 MGHs Uplink-137-138 MGHz Downlink
-handheld devices Rs.4500 to 22500
-operaional 1995
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BIG LEO
Ex: i)Irridium (Motorola)
ii) Loral
iii) Global Star (Qualcomm)
iv) Oddyssey (TRW)
Objectives 1. Voice and data
2.Frequency between 1 and 3 GHz
3.Processing transponder4.Packet oriented
5.Error detection and correction
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WIRELESS LANDSCAPE
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THANK YOU