The actual RACH failure is only due to collision of RACHs since any subscriber can think of starting a call/sending sms at any time so probibility of collisions are high in RACH phase. But it would not be pegged in any stat at any vendor.
The RACH failure which is pegged at some vendors is the RACH failure detected after reception of a RACH.
This failure can be due to CRC check fail of this received RACH, UL level below set threshold. Distance exceeds TA limit.
I cant help but overlook that there is a serious issue with the formula of SDCCH_assign_unsuccess_rate ( SDNAUR )as MC149 seems added and then subtracted..
Is it just for the easy of understanding also what are the failures that are counted in [MC148 – MC01 – MC02 – MC149] as they are neither blocking not, Channel not available nor is it MS_Access. So what is it due to.
Also I dont think RACH discards due to CRC failure, too low UL Level and Dist_limit are pegged at Alcatel.
The Requests is actually the number of “allocations” (mc148) + number of “congestions” (mc04). This is an approximation…
The failures_BSS are the difference between the allocations and the success + failures_radio. All the allocations that do not become success or fail_radio, then you might wonder what happened to them. We count them as “fail BSS”.
Let me know if you have any doubt.
RACH failures are not counted in alcatel, that’s correct.