What can be done to avoid RACH fail in 5G SA as RACH is contention based?

5G NR
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1

Hi All.

What can be done to avoid RACH fail in 5G SA as RACH is contention based?

2

Depends on the reaosn of failure

3

Hi all ,
Hope you are doing well , Need your help can someone send step by step in NSA Nr RACH procedure steps how it happens sequential flow meesage if possible I.E context i would be appreciate

4

Although 5G SA initial access mainly uses Contention-Based Random Access (CBRA), RACH failures can be minimized through proper radio planning and parameter optimization rather than trying to eliminate contention itself.

Some key areas to check are:

  • PRACH coverage and uplink radio conditions (low SINR/high path loss can cause Msg1 or Msg3 failures).

  • Preamble power ramping configuration and maximum retransmissions.

  • PRACH configuration index and RACH occasion availability.

  • Root Sequence Index (RSI) planning to avoid interference and preamble conflicts.

  • Beam alignment and coverage optimization, especially in SA deployments.

  • Contention Resolution failures (Msg4 not received successfully).

  • Uplink interference and poor UL coverage, which often result in Msg3 decoding failures.

In practice, the first step is to identify whether the failure is occurring at Msg1, Msg2, Msg3, or Msg4 stage. Once the failure point is known, optimization becomes much easier.

For detailed explanation of the 5G NR Random Access procedure, this guide on 5G NR RACH is useful: :backhand_index_pointing_right: https://techlteworld.com/rach-in-5g-nr/

Also, this detailed article explains the complete RACH procedure, CBRA/CFRA concepts, and MSG1–MSG4 flow: :backhand_index_pointing_right:
https://techlteworld.com/rach-random-access-control-channel-in-lte-2/