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8/3/2019 Evolution From GSM Towards UMTS
http://slidepdf.com/reader/full/evolution-from-gsm-towards-umts 1/32
Evolution From GSM to UMTS
8/3/2019 Evolution From GSM Towards UMTS
http://slidepdf.com/reader/full/evolution-from-gsm-towards-umts 2/32
Evolution From GSM to UMTS
Steps on the way to 3G
HSCSD
GPRS
EDGE
UMTS
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HSCSD(High Speed Circuit Switched Data)
Introduction
Next step of GSM data development
High speed access to data services
Circuit switched connection
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HSCSD(High Speed Circuit Switched Data)
HSCSD technology New channel coding scheme
(increase the data rate to 14.4 kbps)
Possibility of combining time slots
(variety of bit rates from 14.4 to 57.6 kbps)
Using different data rates in the uplink andthe downlink direction
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HSCSD(High Speed Circuit Switched Data)
Symmetrical connection(2+2)
2 time slots for the uplink
2 time slots for the downlink
Asymmetrical connection
(3+1)
1 time slots for the uplink
3 time slots for the downlink
Example: downloading a
web page
8/3/2019 Evolution From GSM Towards UMTS
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HSCSD(High Speed Circuit Switched Data)
Type of connection speeds
Normal connection speed Max connection speed
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8/3/2019 Evolution From GSM Towards UMTS
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HSCSD(High Speed Circuit Switched Data)
Applications requiring HSCSD1. Transparent applications (fax ,video)
2. Non transparent applications (www ,email)
Examples1. Email sending and receiving
2. www browsing
3. File transfer4. Real times applications
5. Time critical wireless imaging
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HSCSD(High Speed Circuit Switched Data)
Disadvantage of HSCSD
Limited number of user
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GPRS(General Packet Radio Service)
Introduction
Permits packet switched besides circuit switched
It is an expansion of GSM and a main step towards 3G Charging is no longer based on the transmission time
Data rate depends on the coding scheme (CS1 CS4)
with a max theoretical data rate 171.2 kbps
8/3/2019 Evolution From GSM Towards UMTS
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GPRS(General Packet Radio Service)
How to upgrade a GSM network to GPRS?
1. For the BSS software upgrade
hardware upgrade
(PCU)
2. New GPRS support nodes (SGSN – GGSN)
8/3/2019 Evolution From GSM Towards UMTS
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GSMNetwork
PSTN
BSC
GSM
BTS
GSMBTS
MSC
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PSTN
BSC
GSMBTS
GSMBTS
MSC
GSM + GPRSNetwork
PCU
Other nets
GGSN
SGSN
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Node B Node B
RNC
PSTN
BSC
GSMBTS
GSMBTS
PCU
Other nets
GGSN
SGSN
GSM & UMTSNetwork
GGSN
SGSNMSCu u
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GPRS Coding Schemes
GPRS using samephysical RF layer asGSM speech
Data is coded intonormal bursts (456bits / 20ms)
Coding
Scheme
Coded
bits
Data
Rate(kbps)
Multiple
SlotMax.
Data
Rate
(kbps)
CS-1 456 9.05 72.4
CS-2 588 13.4 107.2
CS-3 676 15.6 124.8
CS-4 456 21.4 171.2Max. Per TS Data rate (kbps)
0
5
10
15
20
25
CS-1 CS-2 CS-3 CS-4
K B i t s p e r S e c o n d
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GPRS Coding Schemes
Coding Scheme User Data Rate / TS Error correction Max throughputwith 8TS
CS-1 9.05 Kbps High 72.4 Kbps
CS-2 13.4 Kbps Medium 107.2 Kbps
CS-3 15.6 Kbps Low 124.8 Kbps
CS-4 21.4 Kbps None 171.2 Kbps
Higher data rate for increased throughput
Benefits
• Improved user perception
• Potential for new revenue streams (new applications / higher grade of service)
• Opportunity for market differentiation
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Timeslot sharing
BTS
BCCH GPRS GPRS GPRSTCHTCH TCH User rate at
CS2 = 40.2 kbps
TCH
A Voice call require the GPRS TS
Site with one carrier will be able to share time slots (Voice and GPRS)
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Timeslot sharing
BTS
BCCH GPRS GPRSTCH TCH TCHTCH User rate at
CS2 = 40.2 kbps
TCH
A Voice call takes the GPRS TS
User rate at
CS2 = 26.8 kbps
Site with one carrier will be able to share timeslots (Voice and GPRS)
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BTS
BCCH GPRS GPRS GPRS GPRS GPRS GPRS GPRS
MAX
CS2 = 93.8 kbps
BTS
BCCH TCH TCH TCH TCH TCH TCH
CS2 = 13.4 kbps
GPRS
Dynamic allocation of channels between circuit and packet:
Channel sharing
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(And more economical)
ADVANTAGES OF GPRS
1. Faster data transfer rates up to 115 kbps bydedicating all 8 time slots to GPRS
GPRSGSM
Higher data rate
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ADVANTAGES OF GPRS
2. Always on connection :
Eliminates lengthy delays required to
reconnect to the network to send andreceive data
Information can be pushed to the end user
in real time Bill by the packet (data exchanged) and
type of service rather than by minute
8/3/2019 Evolution From GSM Towards UMTS
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ADVANTAGES OF GPRS
3. Robust connectivity:
First the coding scheme is
selected depending on theradio conditions
If error is detected in a framereceived in the BSS, the frame
is retransmitted until properlyreceived before passing it onthe GPRS core network
8/3/2019 Evolution From GSM Towards UMTS
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ADVANTAGES OF GPRS
4. Broad application support
Fully enable internet applications (e-mail, web
access, instant messaging and file transfer) multimedia web content
Chat, visual information, still images, movingimages and document sharing
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ADVANTAGES OF GPRS
5. Security support
GPRS builds on the authentication and
security model of GSM It enables an additional authentication
using protocols like RADIUS before thesub is allowed to access to the internet or
other data networks
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EDGE(Enhanced Data Rate for GSM Evolution)
Introduction Increase data rates up to 384 kbps
Introduces a new modulation
technique (8PSK) and channel coding The last step before UMTS
It is built on an existing GSM/GPRS
system
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EDGE(Enhanced Data Rate for GSM Evolution)
Have the same symbol rate of GMSK Each symbol is represented by 3 bits
8PSK generates same interference on adjacent
channels as GMSK. We use the same channel structure and width
and frequency plan of GPRS
The distance between symbols is shorter using8PSK than GMSK misinterpretation
8/3/2019 Evolution From GSM Towards UMTS
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EDGE(Enhanced Data Rate for GSM Evolution)
Packet handling The ability of
retransmission of packets with a morerobust coding scheme
Unlike GPRS in which
retransmission of packets is made withthe same codingscheme
8/3/2019 Evolution From GSM Towards UMTS
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EDGE(Enhanced Data Rate for GSM Evolution)
Impact of EDGE on existing GSM/GPRS networks
Hardware upgrade to the BSS (new transceiver ineach cell)
Software upgrade to the BS and BSC No change in the core networks New terminals
- Terminal which provides 8PSK in the uplink and
the downlink - Terminal which provides GMSK in the uplink and 8PSK in the downlink
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GPRS -- COMPLEXITY
SGSN
GGSN
Gb
Gn
Gc
Gi
Gs
Gn
HLR
BSC
MSC
PSTN
BTS
BTS
Abis A
D
Abis
A
PDN
NEW
NEWNEW
NEW
NEW
NEW
NEW
NEW
NEW
NEWNEW
NEW
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EDGE -- EVOLUTION
SGSN
GGSN
Gb
Gn
Gc
Gi
Gs
Gn
HLR
BSC
MSC
PSTN
BTS
BTS
Abis A
D
Abis
A
PDN
NEW
NEW
8/3/2019 Evolution From GSM Towards UMTS
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EDGE(Enhanced Data Rate for GSM Evolution)
EDGE benefits Short-term benefits: Capacity and
performance Easy implementation on a GSM/GPRS
network Cost effective
Increase the capacity and the data rateof GPRS
Enabling new multimedia services
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Evolution From GSM to UMTS