Can we reserve the Preamble for Timing advance Rach request?

Question

Can anyone tell me, when UE ignores Timing Advance when timeAlignment Timer is running?

Answer 1

Hi Karan,

Rach preambles are two types, one is Dedicated and contention based. If TA is expired eNB can request an PO Rach for UE. eNB sends DCI for initiating an PDcch Order Raach but here preamble index is optional, so eNB can send or UE can select. to answer your questions eNB doesn't always reserve preamble for PO.