Q:RACH re-transmission procedure

[peanut]

Gents,

Could you provide a simplified explanation for the RACH re-transmission procedure, especially the parameters:

max re-transmission
tx integer

Appreciate any help,

[mout94]

Hi Peanut,

UE in idle state, will receives sib messages, sib1(T3212, T312, N312, T300, N300…), sib5 (CPICH Power, ConstantValue, PowerPreambleStep,MaxPreambleRetrans, MaxPreambleCycle, PowerOffset P_pm…), sib7(RSSI mesured...) and so on.

After that, UE will decodes sib7 especially then send the first Rach with prach initial power to nodeb, if it is succeful received, nodeb will response with aich message otherwise UE will will increase the power of message by power ramping step (during a preamble ramping cycle) until the nodeb receive it correctly.

Once the control part is received, the UE will add a message power offset to send the data part message (rach=control+data part message).
Hereafter, the formula needed:
Preamble_Initial_Power = PCPICHPower – CPICH_RSCP + UL interference + Constantvalue

Hoping that will help you understanding rach procedure.

Don't forget reputation plz.
:p

[peanut]

Hi mout94,
Thanks for the reply, actually I'm asking about GSM re-transmission wich is different from 3G.

Apreciate some flashs on that subject,

Regards,