EGDE - Enhanced Data rates for GSM Evolution

(E)GPRS Network Infrastructure

How to calculate what

•          No. of EGPRS resources used in 1 sector * No. of sectors : 2 x 3

•           No. of time slot/sector * no of time slot used for EDAP :- 2 * 3 = 6

•          So total time slots per site 6 + 6 = 12

•          1 NSEI support 256 time slot with upgrade % as 10 so total no of time slots which can be equipped is 256 - 10% of 256 = 230.4 ~ 230

•          So no. of sites per NSEI is 230/12 = 19.16 ~ 19

•          So no NSEI required / BSC :  100 / 19 = 5.2 +1 (for future use) ~ 6

•          2 NSEI supports 1 BCSU so no. of PCU required : 6/2 = 3

•          No. of NSEI required is equivalent to the no. of Gb link = 3

•          On 1 E1 we can get 31x64 = 1984 , so access rate can be given by 1 E1 = 1984/ access rate (256) = 1984 / 256  ~  7

Transmission requirement for EGPRS coding schemes in Abis interface

EDGE modulations

  

Scheme	Modulation	Maximum rate [kb/s]
MCS-9	8PSK	59.2
MCS-8		54.4
MCS-7		44.8
MCS-6		29.6 / 27.2
MCS-5		22.4
MCS-4	GMSK	17.6
MCS-3		14.8 / 13.6
MCS-2		11.2
MCS-1		8.8

 

 EDAP utilization

•          6 EGPRS RTSLs (Dedicated + Default territory)

•           50 % utilization assumed (3 Data Erlangs traffic)

•           On average 3 RTSLs used

•          RTSLs use MCS7 (44.8 kbit/s) with average C/I=13dB and throughput 30kbit/s

•           Effective data rate factor excluding retransmissions over the air-interface is 30/44.8 ~ 0.7

•           Slave group utilization is 0.7*0.5= 0.35