Hello experts,

How RACH is decided if CBRA or CFRA is to be used? We seen in the trace that SSB index is present during B1 MR followed by CFRA information. However we also noticed CBRA info.

Is it possible to have CBRA and CFRA in RRC reconfiguration during 5G SG addtion (ENDC) and use CBRA instead of CFRA? What is the use of CFRA if not used in the RRC reconfiguration?

Admin note: this post was updated with image below.

When UE needs RA, if there is RA preamble received from eNB/gNB then CFRA, otherwise CBRA. So if CFRA, there must be a procedure that eNB/gNB allocates RA preamble to UE.

thanks. So its possible then for CFRA and CBRA info to be present on the trace at the same time.

CFRA in 5G

Coordinated Frequency Resource Allocation (CFRA) is a key 5G technique for efficient inter-cell interference management. Through CFRA, neighboring cells coordinate their frequency resource allocation to minimize interference at cell edges. By carefully assigning different frequency resources to cell-edge users, CFRA boosts performance and fairness across the network.

CBRA in 5G

Coordinated Beamforming and Resource Allocation (CBRA) takes inter-cell coordination a step further in 5G. With CBRA, adjacent cells collaborate on their beamforming strategies and resource allocation decisions. This coordination reduces interference while maximizing capacity and quality of service for all users, especially those at cell edges.

As 5G networks densify, advanced coordination schemes like CFRA and CBRA will play a crucial role in mitigating inter-cell interference and delivering a consistent, high-performance user experience.