4 2g evolution

8/22/2019 4 2G Evolution

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Evolution of 2G Systems


2/21

Background

2G Systems

GSM, IS-136, IS-95

Circuit Switch architecture

Low rate data capability

9.6 kbps

14.4 kbps (with relax channel coding)

Indirect access to IP network

Expensive solution for data network

HSCSD: High Speed Circuit Switched DataBy allocating up to 4 TDMA slots

57.6 kbps (14.4 kbps 4)

By allocating multiple codes (up to 8)

IS-95B

115.2 kbps (14.4 kbps 8) but practically 64 kbps


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Evolution Path for 2G Technologies

IS-95 IS-136GSM

EDGE

GPRS

HSCSDIS-95B

cdma2000-1xRTT

cdma2000-1xEV,DV,DO

Cdma2000-3xRTT

W-CDMA

EDGE

TD-SCDMA

2G

3G

2.5G

3GPP3GPP2


4/21

GSM Evolution

Enhanced data capability in a cost effective manner

GPRS (General Packet Radio Service)

Packetized data transmission

More centric to network

EDGE (Enhance Data rates forGlobal Evolution)

Multiple modulation and coding format

More centric to RAN (Radio Access Network)


5/21

GPRS

Packet Switch architecture

End to End IP service (mobile = IP host)

Resources are reserved only when needed and charged

accordingly

Enables new service opportunities

Supports multi user network sharing of individual radio

channels and time slots

Provides packet network on dedicated GSM radio

channels

GPRS overlays a packet-switched architecture on

existing GSM network architecture


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GPRS Architecture


7/21

GPRS Architecture (contd.)


8/21

New Interfaces


9/21

Evolution of BSS

New hardware in BSS

Packet Controlling Unit (PCU)

Can be compared to TRAU function in GSM

Generally located in the BSC

Heart of the packet transmission in BSS network

Allows the dynamic traffic allocationProvide the radio resource management mechanism, adapted to

packet transfer


10/21

Evolution of BSS (contd.)

Frame relay (uses virtual circuit concept)


11/21

New Core Equipments


12/21

Statistical Multiplexing

Random Packet AccessUp to 8 time slots can be combined

Throughput depends on coding scheme, # timeslots


13/21

Coding Schemes

Variable channel coding rate based on channel SNR

Less protection when SNR is good

More protection when SNR is poor

Uses 4 different coding schemes


14/21

CS1 guarantees connectivity under all conditions (signaling and start of data)

CS2 enhances the capacity and may be utilized during the data transfer phase

CS3/CS4 will bring the highest speed but only under good conditions

0

4

8

12

16

20

3dBdB1dB5dB9dB3dB7dB C/IMaxthroughputpe

rGPRSchannel

(kbit/sec)

CS 4

CS 3

CS 2CS 1

Coding Schemes (contd.)


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Coding Schemes (contd.)

In GSM, channel coded rate = 22.8 kbps

456 bits per 20 ms slot

In GPRS

CS1 = 8.0 kbps (8 8.0 = 64 kbps)

CS2 = 12.0 kbps (8

12.0 = 96 kbps)CS3 = 14.4 kbps (8 14.4 = 115.2 kbps)

CS4 = 20.0 kbps (8 20.0 = 160 kbps)

GMSK modulation

Bit rate at RF = 270 kbps


16/21

Evolution of the radio interface

Uses Adaptive modulation and coding schemes

Uses 8-PSK modulation in good conditions

Uses 9 Modulation Coding Schemes (MCS1-9)MCS(1-4) uses GMSK

MCS(5-9) uses 8PSK modulation

Theoretical peak data rate 473.6kbps (8 59.2 kbps)

Practically data rates of 384 kbps

EDGE


17/21

MCS


18/21

The code rate indicates how much of the packet is data (includingheaders) and how much is error checking code

MCS3 indicates that 15% of the packet is error checking code

Modulation Data Rate Modulation Technique Code Rate

MSC1 8.8 Kbps GMSK 0.53



MSC4 17.6 Kbps GMSK 1

MSC5 22.4 Kbps 8PSK 0.37MSC6 29.6 Kbps 8PSK 0.49

MSC7 44.8 Kbps 8PSK 0.76

MSC8 54.4 Kbps 8PSK 0.92

MSC9 59.2 Kbps 8PSK 1

MCS (contd.)


19/21

Upgradation Requirements


20/21

Upgradation Requirements

EDGE capable TRX need to be added, old BTS might have to be changed,

BSC/PCU shall support EDGE capability.

Re-dimensioning of the interface according to the traffic growth.


21/21

Evolution of IS-95

IS-95B

By allocating multiple codes (up to 8)

Peak data rate 115.2 kbps (14.4 kbps 8)

Practically 64 -115 kbps

4 2g evolution

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