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osmo-bts-trx: add extended (11-bit) RACH support 

Attempt to decode incoming RACH burst as 11-bit first
and fallback to 8-bit if unsuccessful.

Change-Id: Ia28741603636406744e5e22ffff1fb7a9689955a
Related: OS#1854
This commit is contained in:
Max 2018-01-04 11:48:05 +01:00
parent 3933e930c3
commit de9e2092c9
1 changed files with 38 additions and 10 deletions
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48
src/osmo-bts-trx/scheduler_trx.c
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@ -716,18 +716,29 @@ int rx_rach_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
uint8_t chan_nr;
struct osmo_phsap_prim l1sap;
int n_errors, n_bits_total;
bool is_11bit = true;
uint16_t ra11;
uint8_t ra;
int rc;
int rc = 1;
chan_nr = trx_chan_desc[chan].chan_nr | tn;
LOGL1S(DL1P, LOGL_DEBUG, l1t, tn, chan, fn, "Received RACH toa=%d\n", toa256);
/* decode */
rc = gsm0503_rach_decode_ber(&ra, bits + 8 + 41, l1t->trx->bts->bsic, &n_errors, &n_bits_total);
if (chan == TRXC_RACH) /* Attempt to decode as extended (11-bit) RACH first */
rc = gsm0503_rach_ext_decode_ber(&ra11, bits + 8 + 41,
l1t->trx->bts->bsic, &n_errors, &n_bits_total);
if (rc) {
LOGL1S(DL1P, LOGL_DEBUG, l1t, tn, chan, fn, "Received bad AB frame\n");
return 0;
/* Indicate non-extended RACH */
is_11bit = false;
/* Fall-back to the normal RACH decoding */
rc = gsm0503_rach_decode_ber(&ra, bits + 8 + 41,
l1t->trx->bts->bsic, &n_errors, &n_bits_total);
if (rc) {
LOGL1S(DL1P, LOGL_DEBUG, l1t, tn, chan, fn, "Received bad AB frame\n");
return 0;
}
}
/* compose primitive */
@ -736,17 +747,34 @@ int rx_rach_fn(struct l1sched_trx *l1t, uint8_t tn, uint32_t fn,
osmo_prim_init(&l1sap.oph, SAP_GSM_PH, PRIM_PH_RACH, PRIM_OP_INDICATION,
NULL);
l1sap.u.rach_ind.chan_nr = chan_nr;
l1sap.u.rach_ind.ra = ra;
l1sap.u.rach_ind.acc_delay = (toa256 >= 0) ? toa256/256 : 0;
l1sap.u.rach_ind.fn = fn;
/* 11bit RACH is not supported for osmo-trx */
l1sap.u.rach_ind.is_11bit = 0;
l1sap.u.rach_ind.burst_type = GSM_L1_BURST_TYPE_ACCESS_0;
l1sap.u.rach_ind.rssi = rssi;
l1sap.u.rach_ind.ber10k = compute_ber10k(n_bits_total, n_errors);
l1sap.u.rach_ind.acc_delay_256bits = toa256;
if (is_11bit) {
l1sap.u.rach_ind.is_11bit = 1;
l1sap.u.rach_ind.ra = ra11;
l1sap.u.rach_ind.burst_type = BSIC2BCC(l1t->trx->bts->bsic);
switch (l1sap.u.rach_ind.burst_type) {
case GSM_L1_BURST_TYPE_ACCESS_0:
case GSM_L1_BURST_TYPE_ACCESS_1:
case GSM_L1_BURST_TYPE_ACCESS_2:
break;
default:
LOGL1S(DL1P, LOGL_NOTICE, l1t, tn, chan, fn,
"Received RACH frame with unexpected TSC %u, "
"forcing default %u\n", l1sap.u.rach_ind.burst_type,
GSM_L1_BURST_TYPE_ACCESS_0);
l1sap.u.rach_ind.burst_type = GSM_L1_BURST_TYPE_ACCESS_0;
}
} else {
l1sap.u.rach_ind.is_11bit = 0;
l1sap.u.rach_ind.ra = ra;
l1sap.u.rach_ind.burst_type = GSM_L1_BURST_TYPE_ACCESS_0;
}
/* forward primitive */
l1sap_up(l1t->trx, &l1sap);