Hi all.
I've noticed in osmo-bts logs several messages from L1: 238:<0006> oml.c:689 (bts=0,trx=0,ts=2,ss=0) MPH-ACTIVATE.conf (PDTCH TxDL) 243:<0006> oml.c:689 (bts=0,trx=0,ts=3,ss=0) MPH-ACTIVATE.conf (PDTCH TxDL) 246:<0006> oml.c:689 (bts=0,trx=0,ts=2,ss=0) MPH-ACTIVATE.conf (PDTCH RxUL) 251:<0006> oml.c:689 (bts=0,trx=0,ts=4,ss=0) MPH-ACTIVATE.conf (PDTCH TxDL) 254:<0006> oml.c:689 (bts=0,trx=0,ts=3,ss=0) MPH-ACTIVATE.conf (PDTCH RxUL) 260:<0006> oml.c:689 (bts=0,trx=0,ts=7,ss=0) MPH-ACTIVATE.conf (PDTCH TxDL) 263:<0006> oml.c:689 (bts=0,trx=0,ts=4,ss=0) MPH-ACTIVATE.conf (PDTCH RxUL) 274:<0006> oml.c:689 (bts=0,trx=0,ts=7,ss=0) MPH-ACTIVATE.conf (PDTCH RxUL)
Similarly, there are messages related to PTCCH: 257:<0006> oml.c:689 (bts=0,trx=0,ts=2,ss=0) MPH-ACTIVATE.conf (PTCCH TxDL) 266:<0006> oml.c:689 (bts=0,trx=0,ts=3,ss=0) MPH-ACTIVATE.conf (PTCCH TxDL) 277:<0006> oml.c:689 (bts=0,trx=0,ts=4,ss=0) MPH-ACTIVATE.conf (PTCCH TxDL) 288:<0006> oml.c:689 (bts=0,trx=0,ts=7,ss=0) MPH-ACTIVATE.conf (PTCCH TxDL)
Notice that while PDTCH is activated for both UL and DL, the PTCCH is only activated for DL.
As far as I've understood continuous TA procedure I've got to have PTCCH activated in both directions. The problem is that I have troubles locating the code which triggers the activation above.
There is l1if_connect_pdch() in osmo-pcu src/sysmo_l1_if.c but it uses GsmL1_PrimId_MphConnectReq while if I understood correctly GsmL1_PrimId_MphActivateReq is necessary for channel activation. There is mph_send_activate_req() in osmo-bts oml.c which uses it. It's called from lchan_act_compl_cb() via sapi_queue_send() which is also in mph_send_activate_req() - I have hard time understanding how this works at all. Do we have this documented somewhere?