OFH 7.2 Incorrect PRACH C-plane packet

[saki92]

Description

I am trying to connect OAI UE with the gNB running with a Foxconn RU. I took the base configuration from configs/gnb_ru_rpqn4800e_tdd_n78_20mhz_2x2.yml and changed only ARFCN, IF name and MAC addresses.

The gNB starts and UE decodes SIB1 but fails at RA. The gNB logs don't show any PRACH attempts. When I look at the FH capture, I found the gNB is requesting PRACH IQ from PRB 0 to 11 while the config file has prach_frequency_start: 12. I tried changing it to 0 and I see a warning that it conflicts with PUCCH resources but still no PRACH received at gNB.

Prach Freq Start: 12

gNB logs: gnb.log

FH capture: srsran_20mhz_oai_ue_prach.zip

The UE attempted PRACH in frames (80, 2, 92)

Prach Freq Start: 0

gNB logs:
gnb_prach0.log

FH capture:
srsran_20mhz_oai_ue_prach0.zip

Note
The same configuration works with USRP.