Issue with UE-gNB Connection: RACH Failure in OAI Setup on Powder
SAI MEGHANA KUCHANA
I am currently encountering an issue while attempting to connect a single UE to a single gNB using the following setup on Powder:
CoreNetwork forked from: oai-cn5g-fed.git (Branch: 2024.w45)
RAN forked from: openairinterface5g.git (Branch: 2025.w42)
The Core Network is deployed using docker-compose-basic-nrf.yaml
I'm launching the components using the following commands:
gNB: sudo RFSIMULATOR=server ./ran_build/build/nr-softmodem --rfsim -O /local/repository/etc/gnb.conf
UE: sudo RFSIMULATOR=127.0.0.1 ./ran_build/build/nr-uesoftmodem -O /local/repository/etc/ue.conf -r 106 -C 3619200000 --numerology 1 --band 78 --rfsim --rfsimulator.options chanmod
Error: Although synchronization completes successfully, the UE fails during the Random Access procedure. The following error repeatedly appears in the logs:
UE logs:
[PHY] Initial sync successful, PCI: 0
[PHY] HW: Configuring channel 0 (rf_chain 0): setting tx_freq 3619200006 Hz, rx_freq 3619200006 Hz, tune_offset 0
[PHY] Got synch: hw_slot_offset 16, carrier off 6 Hz, rxgain 0.000000 (DL 3619200006.000000 Hz, UL 3619200006.000000 Hz)
[PHY] UE synchronized! decoded_frame_rx=502 UE->init_sync_frame=0 trashed_frames=26
[PHY] Resynchronizing RX by 243536 samples
[HW] received write reorder clear context
[NR_RRC] SIB1 decoded
[NR_MAC] TDD period index = 6, based on the sum of dl_UL_TransmissionPeriodicity from Pattern1 (5.000000 ms) and Pattern2 (0.000000 ms): Total = 5.000000 ms
[NR_MAC] Set TDD configuration period to: 8 DL slots, 3 UL slots, 10 slots per period (NR_TDD_UL_DL_Pattern is 7 DL slots, 2 UL slots, 6 DL symbols, 4 UL symbols)
[NR_MAC] Configured 1 TDD patterns (total slots: pattern1 = 10, pattern2 = 0)
[MAC] Initialization of 4-Step CBRA procedure
[NR_MAC] PRACH scheduler: Selected RO Frame 531, Slot 19, Symbol 0, Fdm 0
[PHY] PRACH [UE 0] in frame.slot 531.19, placing PRACH in position 2828, Msg1/MsgA-Preamble frequency start 0 (k1 0), preamble_offset 8, first_nonzero_root_idx 0, preambleIndex = 32
[MAC] [UE 0] RAR reception failed
[NR_MAC] PRACH scheduler: Selected RO Frame 533, Slot 19, Symbol 0, Fdm 0
[PHY] PRACH [UE 0] in frame.slot 533.19, placing PRACH in position 2828, Msg1/MsgA-Preamble frequency start 0 (k1 0), preamble_offset 2, first_nonzero_root_idx 0, preambleIndex = 10
[MAC] [UE 0] RAR reception failed
[NR_MAC] PRACH scheduler: Selected RO Frame 535, Slot 19, Symbol 4, Fdm 0
[PHY] PRACH [UE 0] in frame.slot 535.19, placing PRACH in position 2828, Msg1/MsgA-Preamble frequency start 0 (k1 0), preamble_offset 2, first_nonzero_root_idx 0, preambleIndex = 8
[MAC] [UE 0] RAR reception failed
gNB logs:
[NR_PHY] [RAPROC] 537.19 Initiating RA procedure with preamble 38, energy 42.5 dB (I0 89, thres 120), delay 0 start symbol 0 freq index 0
[NR_MAC] 537.19 UE RA-RNTI 010b TC-RNTI c209: initiating RA procedure
[NR_MAC] exceeded RA window: preamble at 537.19 now 538.10 (diff 11), ra_ResponseWindow 4/10 slots
[NR_MAC] UE RA-RNTI 010b TC-RNTI c209: exceeded RA window, cannot schedule Msg2
[NR_MAC] Remove NR rnti 0xc209
[NR_PHY] [RAPROC] 539.19 Initiating RA procedure with preamble 26, energy 42.2 dB (I0 87, thres 120), delay 0 start symbol 4 freq index 0
[NR_MAC] 539.19 UE RA-RNTI 010f TC-RNTI c563: initiating RA procedure
[NR_MAC] exceeded RA window: preamble at 539.19 now 540.10 (diff 11), ra_ResponseWindow 4/10 slots
[NR_MAC] UE RA-RNTI 010f TC-RNTI c563: exceeded RA window, cannot schedule Msg2
[NR_MAC] Remove NR rnti 0xc563
[NR_PHY] [RAPROC] 541.19 Initiating RA procedure with preamble 15, energy 42.1 dB (I0 111, thres 120), delay 0 start symbol 0 freq index 0
[NR_MAC] 541.19 UE RA-RNTI 010b TC-RNTI d001: initiating RA procedure
[NR_MAC] exceeded RA window: preamble at 541.19 now 542.10 (diff 11), ra_ResponseWindow 4/10 slots
[NR_MAC] UE RA-RNTI 010b TC-RNTI d001: exceeded RA window, cannot schedule Msg2
[NR_MAC] Remove NR rnti 0xd001
As suggested in the NR_SA_Tutorial, I have also tried adjusting the timing advance using the -A option on the UE and/or gNB side(e.g., -A 45, -A 40, -A 50), but the issue still persists.
Screenshots of the relevant logs from both gNB and UE are attached for reference. I also added the config files for reference. I would sincerely appreciate any suggestions or guidance you might have to help resolve this issue.
Thank you very much for your time and support.
Sai Meghana Kuchana
Dustin Maas
Hi Sai,
Can you share a link to a running experiment? Also, did you modify the source code?
-Dustin
--
You received this message because you are subscribed to the Google Groups "Powder Users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to powder-users...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/powder-users/c58cf442-7aba-45ad-848e-2e94fe4b89fen%40googlegroups.com.
SAI MEGHANA KUCHANA
This is my experiment link: https://www.powderwireless.net/instantiate.php?profile=d9af1095-b053-11f0-bc80-e4434b2381fc&rerun_instance=e1195674-b085-11f0-bc80-e4434b2381fc
Experiment profile: https://www.powderwireless.net/p/nyunetworks/ReorderingOAI_stable
I have forked the CN and RAN into my github repository: https://github.com/saimeghanakuchana/ReorderingOAI_stablerelease/
I haven't made any changes to the Core Network or RAN.
Thank you
Sai
Dustin Maas
To view this discussion visit https://groups.google.com/d/msgid/powder-users/bbe75101-7dbf-4987-8609-1813a33d080fn%40googlegroups.com.
SAI MEGHANA KUCHANA
Please check this: https://www.powderwireless.net/status.php?uuid=e1195674-b085-11f0-bc80-e4434b2381fc
Experiment Name:
| saimeghk-275468 |
Thanks
Sai
You received this message because you are subscribed to a topic in the Google Groups "Powder Users" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/powder-users/coOK9LT9c0Y/unsubscribe.
To unsubscribe from this group and all its topics, send an email to powder-users...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/powder-users/f4014c5f-d6f4-4c55-954c-2ee3601f4db8%40Spark.