Cellular Networks

◼ First Generation
◼ Analog Systems
◼ Analog Modulation, mostly FM
◼ AMPS
◼ Voice Traffic
◼ FDMA/FDD multiple access
◼ Second Generation (2G)
◼ Digital Systems
◼ Digital Modulation
◼ Voice Traffic
◼ TDMA/FDD and CDMA/FDD multiple access
◼ 2.5G
◼ Digital Systems
◼ Voice + Low-datarate Data
◼ Third Generation
◼ Digital
◼ Voice + High data rate DATA
◼ Multimedia Transmission also

47
2nd Generation Cellular Networks
◼ 2 G networks include 3 TDMA and 1 CDMA based standards.

◼ GSM:
◼ 8 time slotted users for each 200kHz channel
◼ Deployed in cellular and PCS bands(Europe, Asia, Australia
and South America)
◼ IS-136(USDC/NADC):
◼ Supports 3 time slotted users in each 30 kHz channel
◼ Deployed in cellular and PCS bands(North and South America
and Australia)
◼ PDC: Japanese digital standard similar to IS136
◼ IS-95(cdma One):
◼ Supports 64 orthogonally coded users on 1.25MHz channel

48
2nd Generation Cellular Networks
◼ 2G standards were first to rely on digital modulation on
air interface and sophisticated DSP both in handsets and
BS.
◼ 2G networks were deployed for conventional mobile
telephony.
◼ In 2001 major carriers decided in favor of 3G systems
based on TDMA based GSM platform instead of IS136
and PDC.

49
2G Technologies
cdmaOne (IS-95) GSM, DCS-1900 IS-54/IS-136
PDC
Uplink Frequencies (MHz) 824-849 (Cellular) 890-915 MHz (Eurpe) 800 MHz, 1500 Mhz
1850-1910 (US PCS) 1850-1910 (US PCS) (Japan)
1850-1910 (US PCS)
Downlink Frequencies 869-894 MHz (US Cellular) 935-960 (Europa) 869-894 MHz (Cellular)
1930-1990 MHz (US PCS) 1930-1990 (US PCS) 1930-1990 (US PCS)
800 MHz, 1500 MHz
(Japan)
Deplexing FDD FDD FDD
Multiple Access CDMA TDMA TDMA
Modulation BPSK with Quadrature GMSK with BT=0.3 DQPSK
Spreading
Carrier Seperation 1.25 MHz 200 KHz 30 KHz (IS-136)
(25 KHz PDC)
Channel Data Rate 1.2288 Mchips/sec 270.833 Kbps 48.6 Kbps (IS-136)
42 Kbps (PDC)
Voice Channels per 64 8 3
carrier

50
2G and Data

◼ 2G is developed for voice communications

◼ Data sent using Circuit switching
◼ Provides data rates in the order of ~9.6 Kbps
◼ Increased data rates are required for internet
application
◼ This requires evolution towards new systems:
2.5 G

51
Evolution to 2.5G Mobile Networks
◼ The 2G deployed before the widespread use of
Internet.
◼ limited Internet browsing and short messaging
capability using CS approach.
◼ In effort to provide increased data-rates, new data
centric standards have been developed and overlaid
over existing 2G equipments.
◼ Existing systems were supplemented with hardware
and software upgrade to support high data rates for
web browsing, email, m-commerce and LBS.

52
2.5 Technologies
◼ Evolution of TDMA Systems
❑ HSCSD for 2.5G GSM
❑ Up to 57.6 Kbps data-rate
❑ GPRS for GSM and IS-136
❑ Up to 171.2 Kbps data-rate
❑ EDGE for 2.5G GSM and IS-136
❑ Up to 384 Kbps data-rate

◼ Evolution of CDMA Systems

❑ IS-95B
❑ Up to 64 Kbps

53
Upgrade Paths for 2G Technologies
2G
IS-136
IS-95 GSM
PDC

2.5G
GPRS
IS-95B HSCSD
EDGE

W-CDMA
EDGE

TD-SCDMA

54
 3G
cdma200-1xRTT

cdma2000-1xEV,DV,DO

cdma200-3xRTT

55
2.5 Technologies
◼ HSCSD for 2.5G GSM
◼ Allows a user to use consecutive time slots(TS) in GSM to
obtain high data-rates.
◼ Relaxes error control algorithms and increases data rate to
14.4kbps as compared to 9.6kbps for GSM.
◼ Using 4 consecutive TS, HSCSD provides a raw tx-ion rate of
57.6kbps.
◼ Requires a software upgrade at the GSM BS.
◼ GPRS for GSM and IS-136
◼ General Packet Radio System is Packet based data networks.
◼ Well suited for internet usage.
◼ Supports multi-user network sharing of individual radio
channel and time slot

55
2.5 Technologies
◼ GPRS for GSM and IS-136
◼ Retains the modulation format specified in 2G standard, but
uses completely redefined air interface
◼ With all the time slots dedicated for a GPRS user its able to
achieve data rate of 171.2 kbps(where each slot provides
21.4 kbps raw un-coded date)
◼ Applications are required to provide there own error correction
schemes.
◼ Merely requires new routers and internet gateways at the BS,
and software upgrade to redefine BS air interface.

56
2.5 Technologies
◼ EDGE for 2.5G GSM and IS-136
◼ Enhanced Data rate for GSM evolution.
◼ Requires new hardware and software upgrade at BSs.
◼ Uses 8PSK digital Modulation in addition to GMSK used for GSM
◼ 9 different autonomously selectable air interface format, Multiple
Modulation and Coding Schemes(MCS), with varying degree off
error control protections.
◼ Each MCS state may use GMSK or 8 PSK for network access,
depending on instantaneous demand of network and operating
conditions.
◼ User connection may adaptively determine best MCS
settings for particular radio propagation conditions,
selecting best air interface is called incremental redundancy.
❑ Radio data rate per time slot – 69.2kbps *8=547.2 per channel

57
2.5 Technologies

58
2.5 Technologies
◼ Evolution of CDMA Systems
❑ IS-95B
◼ Support medium data rate(MDR) service by allowing
user to command 8 Walsh codes simultaneously to
provide data rate of 115.2kbps (8*14.4kbps)

◼ In reality only 64kbps is available to a user due to

slotting techniques of the air interface.

59
2.5 Technologies
W ire le ss Requires
Cha nne l Infrastructure
Data Duple x New Re q u ir es New Ha nd sets
BW Cha nge
Tech Spectrum

Requires Yes, New HSCS D ha ndsets provide

Software 57 .6 Kbps on HS CSD n/w and 9 .6 Kbps on
HS CSD 200 KHz FDD No
Upgrade at GSM n/w with dua l mode pho nes. GSM
base station only pho nes will not work in HSCSD N/w.

Re q u ir es new
Ye s , New G PR S ha ndsets work on G P R S
pack et overla y
n/w at 171 .2 Kbps, 9 .6 Kbps on G SM n/w
GPRS 200 KHz FDD inc lu ding No
with dual mo de pho nes. G SM only pho nes
routers and
will not work in G PR S n/w.
gateways

Re q u ir es new
Yes, New handsets work on EDGE n/w at 384
transce iv ers at
Kbps, GPRS n/w at 144 Kbps, and
base station.
EDGE 200 KHz FDD No GSM n/w at 9 .6 Kbps with tri- mode
A ls o, software
pho nes. G SM and G P R S -o nly pho nes will
upgra de to the
not work in E D G E n/w.
BSC & BTS

Y e s , Ne w W-C D M A ha n ds e ts w ill w o rk o n
R e q uire s
W -C D M A a t 2 M b ps , E D G E n/w a t 3 8 4
c o m ple te ly
W -CDMA 5 M Hz FDD Yes K b ps , G P R S n/w a t 1 4 4 K bps . G S M n/w a t
ne w ba s e
9 .9 K bps . O lde r ha n ds e ts w ill no t w o rk i n
s ta tio ns
W -C D M A. 60
 Services roadmap
Improved performance, decreasing cost of delivery

Broadband
3G-specific services take
in wide area
advantage of higher bandwidth
and/or real-time QoS Video sharing
Video telephony
A number of mobile Multitasking Real-time IP

services are bearer multimedia and games

independent in nature WEB browsing Multicasting

Corporate data access

Streaming audio/video
MMS picture / video
xHTML browsing
Application downloading
E-mail
Voice & SMS Presence/location
Push-to-talk
Typical
average bit GSM GPRS EGPRS WCDMA HSDPA
rates 9.6 171 473 2 1-10
(peak rates
higher) kbps kbps kbps Mbps Mbps
◼
2000 1x
CDMA

CDMA

CDMA
EVDO

EVDV
2000-
2000-
61 61
3G Systems

◼ Goals
❑ Voice and Data Transmission
◼ Simultanous voice and data access
❑ Multi-megabit Internet access
◼ Interactive web sessions
◼ Communication using VoIP
❑ Multimedia Content
◼ Live music

62
3G Standards
◼ 3G Standard is created by ITU-T and is called as IMT-2000.

◼ The aim of IMT-2000 is to harmonize worldwide 3G systems

to provide Global Roaming.
3G Systems
◼ Evolution of CDMA Systems
◼ CDMA system evolved to CDMA2000
▪ CDMA2000-1xRTT: Upto 307 Kbps
▪ CDMA2000-1xEV: Evolutionary(Proprietary high data
rate )
▪ CDMA2000-1xEVDO: upto 2.4 Mbps(radio channels
with data only)
▪ CDMA2000-1xEVDV: 144 Kbps datarate (radio
channels with data and voice)
◼ GSM, IS-136 and PDC evolved to W-CDMA (Wideband
CDMA) (also called UMTS)
▪ Up to 2.048 Mbps data-rates
▪ Future systems 8Mbps
▪ Expected to be fully deployed by 2010-2015
3G W-CDMA(UMTS)
◼ UMTS is the European vision of 3G.
◼ UMTS is an upgrade from GSM via GPRS or EDGE.
◼ The standardization work for UMTS is carried out by Third
Generation Partnership Project (3GPP).
◼ Data rates of UMTS are:
❑ 144 kbps for rural

❑ 384 kbps for urban outdoor

❑ 2048 kbps for indoor and low range outdoor

◼ Virtual Home Environment (VHE)

◼ Wide band CDMA technology is selected for UTRAN air interface.
◼ New spectrum is allocated for these technologies i.e. 2500 to
2690, 1710-1885 and 806-960 MHz both for CDMA and
UMTS standards.
3G CDMA 2000
◼ Seamless and evolutionary high data rate for 2G and 2.5 G CDMA, around
1.25 MHz radio channel.
◼ The standardization work for 3G CDMA 2000 is carried out by Third
Generation Partnership Project 2(3GPP2).
◼ First air interface CDMA 2000 1X RTT (1X, 1 time original CDMA channel
bandwidth, RTT, Radio Transmission Technology)
◼ Supports data rate up-to 307kbps
◼ CDMA2000-3xRTT
◼ 3 adjacent (single 3.75 MHz)radio channels used together to provide
data throughput in excess of 2 Mbps, Requires new RF HW at BS
◼ 3 non adjacent channels may be operated as simultaneously in
parallel as 1.25 MHz each
◼ 3G TD-SCDMA (Radio Channel 1.6MHz)
◼ Chinese's standard for 3G, evolution o GSM, adds high data rate
equipment at BS, data only overlay on GSM using TDMA and TDD
3G CDMA 2000
R eq u ires
W ire les s C ha nne l In fra s tru c tu re
D up lex N ew R eq u ires N e w H and se ts
D a ta T ech . BW C ha nge
S pe c trum
Yes, N ew h an d sets w ill w o rk on IS -9 5 B
R eq u ires n ew at 6 4 K bp s an d IS -9 5 A at 1 4 .4 Kb p s.
IS -95B 1 .25 M H z FDD No
so ftw are in B S C C d m a O n e p hon es can w o rk in IS -9 5 B
at 1 4 .4 Kb p s
R eq u ires n ew
s/w in b a ck b o n e
an d n ew ch ann el Yes, N ew h an d sets w ill w o rk on 1 xR TT
C d m a 200 0 1 .25 M H z card s at b ase at 1 4 4 Kb p s, IS -9 5 B at 6 4 K bp s, IS -9 5 A
FDD No
1 xR T T statio n s. A lso at 1 4 .4 Kb p s. O ld er h an d sets can w o rk
n eed to b u ild a in 1 xR T T b u t at lo w er sp eed s.
n ew p acket
service n o d e.
Y es,N ew h an d sets c an w o rk on 1 xE V
C d m a 200 0 R eq u ires s/w
at 2 .4 M bp s, 1 xR T T at 14 4 K bp s, IS-
1 .25 M H z an d d ig ita l card
1 xE V FDD No 9 5 B at 6 4 K b p s, IS-9 5 A at 1 4 .4 K b p s.
u pg rad e o n
(D O & D V ) O ld er h an d sets c an w o rk in 1 xE V b u t at
1 xR T T n etw o rks
lo w er sp e ed s.

R eq u ires
Y es, N ew h an d sets w ill w o rk on 95 A at
b ac kb on e
1 4 .4 K b p s, 95 B at 6 4 K bp s, 1 xR TT at
C d m a 200 0 3 .75 M H z m od if ic atio n s
FDD M ayb e 1 44 K b p s, 3 xR TT at 2 M bp s. O ld er
3 xR T T an d n ew c h ann el
h an d sets c an w o rk in 3 X bu t at lo w er
c ard s at b ase
sp eed s.
statio n s.