What is the UE behavior if SR Rach is fails?

Question

If SR Resource is not configured then UE triggers RACH to acquire UL grant, but if RACH fails or fails to receive UL grant?

Answer 1

UE will perform RRC connection reestablishment if SR RACH is not successful.

Answer 2

UE can ask for the request either using SR or RACH. But even if RACH fails in this case it is more probabale that UE will have Backoff parameter.Backoff Indicator is a special MAC subheader that carries the parameter indicating the time delay between a PRACH and the next PRACH.

Comments

Thanks Bose. You meant to say UE triggers RACH again and again to acquire UL grant.

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yes, but there's a twist. UE cannot retries as many attempt as UE wants. it will drain out it's battery. So UE can max retry upto PreambleMax times.This value decides how many times UE can retry RACH procedure.