Hi
I found this rules in ZTE Dimensioning Guidance for GSM, I hope it can help you:
Abis Interface:
-B Abis =B AbisCS+B AbisPS
-B Abis: Bandwidth of Abis interface.
-B AbisCS: Bandwidth of AbisCS interface.
-B AbisPS: Bandwidth of AbisPS interface.
• BAbisCS= (IE_CS_2G×Vcs_2G+I_TRX×Vsig_TRX)/(1-CAbisCS)/RelayB
• BAbisPS= IMCS9_2G×VMCS9_2G/(1-CAbisPS)/RelayB
In which:
IE_CS_2G: CS Traffic (Erl)
Vcs_2G: Rate of 2G Voice (downlink).
I_TRX: TRX Number
Vsig_TRX: Average Signalling BW per TRX
IMCS9_2G: MCS9 channel Number
VMCS9_2G: Rate of MCS9 Channel(downlink).
CAbisCS / CAbisPS: Transmission overhead for CS /PS service;
RelayB: Utilization of interface
🙂