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L1SAP: refactor handling of Access Bursts on PDCH 

First of all, we also need to apply the same filtering to Access
Bursts on PDCH as for the normal ones on RACH, i.e. filter them
by ToA (Timing of Arrival) and BER (Bit Error Rate).

Secondly, we shall not interpret Access Bursts on PDTCH/U as
handover related ones. Instead, let's print a warning and
ignore them since they are not (yet) supported by OsmoBTS.

Finally, in gsmtap_pdch() we need to set a proper channel type
for Access Bursts received on PDCH (PDTCH/U or PTCCH/U).

Change-Id: I461fde9f4543c45c42b591cd3fd0ff3d98673cec
This commit is contained in:
Vadim Yanitskiy 2019-10-09 02:53:58 +07:00
parent d7103f9172
commit 29e47ffc20
1 changed files with 47 additions and 19 deletions
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66
src/common/l1sap.c
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@ -349,18 +349,27 @@ static int gsmtap_pdch(struct osmo_phsap_prim *l1sap, uint8_t *chan_type,
static int gsmtap_ph_rach(struct osmo_phsap_prim *l1sap, uint8_t *chan_type,
uint8_t *tn, uint8_t *ss, uint32_t *fn, uint8_t **data, unsigned int *len)
{
uint8_t chan_nr;
uint8_t chan_nr = l1sap->u.rach_ind.chan_nr;
*chan_type = GSMTAP_CHANNEL_RACH;
*fn = l1sap->u.rach_ind.fn;
*tn = L1SAP_CHAN2TS(l1sap->u.rach_ind.chan_nr);
chan_nr = l1sap->u.rach_ind.chan_nr;
*tn = L1SAP_CHAN2TS(chan_nr);
if (L1SAP_IS_CHAN_TCHH(chan_nr))
*ss = L1SAP_CHAN2SS_TCHH(chan_nr);
else if (L1SAP_IS_CHAN_SDCCH4(chan_nr))
*ss = L1SAP_CHAN2SS_SDCCH4(chan_nr);
else if (L1SAP_IS_CHAN_SDCCH8(chan_nr))
*ss = L1SAP_CHAN2SS_SDCCH8(chan_nr);
else if (L1SAP_IS_CHAN_PDCH(chan_nr)) {
if (L1SAP_IS_PTCCH(*fn)) {
/* TODO: calculate sub-slot from frame-number */
*chan_type = GSMTAP_CHANNEL_PTCCH;
} else {
*chan_type = GSMTAP_CHANNEL_PDTCH;
}
}
*data = (uint8_t *)&l1sap->u.rach_ind.ra;
*len = 1;
@ -1303,6 +1312,32 @@ static int l1sap_handover_rach(struct gsm_bts_trx *trx, struct ph_rach_ind_param
return 0;
}
/* Special case for Access Bursts on PDTCH/U or PTCCH/U */
static int l1sap_pdch_rach(struct gsm_bts_trx *trx, struct ph_rach_ind_param *rach_ind)
{
/* Filter out noise / interference / ghosts */
if (!rach_pass_filter(rach_ind, trx->bts))
return -EAGAIN;
/* PTCCH/U (Packet Timing Advance Control Channel) */
if (L1SAP_IS_PTCCH(rach_ind->fn)) {
LOGPFN(DL1P, LOGL_DEBUG, rach_ind->fn,
/* TODO: calculate and print Timing Advance Index */
"Access Burst for continuous Timing Advance control (toa256=%d)\n",
rach_ind->acc_delay_256bits);
/* QTA: Timing Advance in units of 1/4 of a symbol */
pcu_tx_rach_ind(trx->bts, rach_ind->acc_delay_256bits >> 6,
rach_ind->ra, rach_ind->fn, rach_ind->is_11bit,
rach_ind->burst_type, PCU_IF_SAPI_PTCCH);
return 0;
} else { /* The MS may acknowledge DL data by 4 consequent Access Bursts */
LOGPFN(DL1P, LOGL_NOTICE, rach_ind->fn,
"Access Bursts on PDTCH/U are not (yet) supported\n");
return -ENOTSUP;
}
}
/* RACH received from bts model */
static int l1sap_ph_rach_ind(struct gsm_bts_trx *trx,
struct osmo_phsap_prim *l1sap, struct ph_rach_ind_param *rach_ind)
@ -1312,22 +1347,15 @@ static int l1sap_ph_rach_ind(struct gsm_bts_trx *trx,
DEBUGPFN(DL1P, rach_ind->fn, "Rx PH-RA.ind\n");
/* PTCCH/UL (Packet Timing Advance Control Channel) */
if (L1SAP_IS_CHAN_PDCH(rach_ind->chan_nr) && L1SAP_IS_PTCCH(rach_ind->fn)) {
LOGPFN(DL1P, LOGL_DEBUG, rach_ind->fn,
/* TODO: calculate and print Timing Advance Index */
"Access Burst for continuous Timing Advance control (toa256=%d)\n",
rach_ind->acc_delay_256bits);
/* QTA: Timing Advance in units of 1/4 of a symbol */
pcu_tx_rach_ind(bts, rach_ind->acc_delay_256bits >> 6,
rach_ind->ra, rach_ind->fn, rach_ind->is_11bit,
rach_ind->burst_type, PCU_IF_SAPI_PTCCH);
return 0;
}
/* check for handover access burst on dedicated channels */
if (!L1SAP_IS_CHAN_RACH(rach_ind->chan_nr)) {
/* Check the origin of an Access Burst */
switch (rach_ind->chan_nr & 0xf8) {
case RSL_CHAN_RACH:
/* CS or PS RACH, to be handled in this function */
break;
case RSL_CHAN_OSMO_PDCH:
/* TODO: do we need to count Access Bursts on PDCH? */
return l1sap_pdch_rach(trx, rach_ind);
default:
rate_ctr_inc2(trx->bts->ctrs, BTS_CTR_RACH_HO);
return l1sap_handover_rach(trx, rach_ind);
}