Isuue With LTE MAC RACH Responce Packet

[michalisk13]

Hi everyone,

I am having this issue when I run scat in debug mode with my SIMCOM8200

2023-12-22 18:45:56,785 scat.qualcommparser (parse_lte_mac_rach_response) WARNING: Unexpected MAC RACH Response Subpacket version 49
2023-12-22 18:45:56,786 scat.qualcommparser (parse_lte_mac_rach_response) DEBUG: Hexdump:
01 00 09 00 01 07 2b ff a6 ff 00 00 01 34 00 06 ......+......4..
00 2c 2e 01 00 12 00 00 20 06 1f 55 8f 3c a0 3a .,.........U.<.:
46 00 96 4b 00 00 16 00 01 00 00 00 07 07 00 00 F..K............

Also, anyone can help me out identify how I can redirect LTE MAC layer info to the loopback interface similar with RRC and NAS messages?
I've tried this using two different modems, EC25 and a newer 5G SIMCOM8200 and no mac layer messages .

Thanks,
Mak

[michalisk13]

I am trying to parse MAC messages without any success.

[peremen]

The LTE MAC PDUs are carried through GSMTAP, and SCAT can parse the MAC PDUs but it is not enabled by default, see diagcmd.py. By default only RAR is parsed, but not all RACH Response packet versions are decoded, so you are getting that error. By enabling the LOG_LTE_MAC_DL_TRANSPORT_BLOCK and LOG_LTE_MAC_UL_TRANSPORT_BLOCK manually in the log_mask_scat_lte() you can get the MAC PDUs.

Also, due to the baseband's limitation, the MAC PDUs may not carry data for traffic channel.

[peremen]

For MAC layer parsing in Quectel EC25, try with the latest trunk with -L mac option.