Change in osmo-bts[master]: bts-trx: Avoid submitting first data_ind with FN=0 to upper layers

pespin gerrit-no-reply at
Thu Mar 11 17:42:02 UTC 2021

pespin has uploaded this change for review. ( )

Change subject: bts-trx: Avoid submitting first data_ind with FN=0 to upper layers

bts-trx: Avoid submitting first data_ind with FN=0 to upper layers

It can happen that the first burst we receive after enabling the PDCH
channel (when PCU connects to the BTS) is bid!=0. As a result,
chan_state->ul_first_fn is never set and defautl value 0 in there is
passed to the upper layers. As a result, when the 2nd block is
transmitted, this time with correct FN, the PCU will see a huge jump in
FNs. Since in PDCH the bursts are always consecutive, let's simply use
bi->fn - 3 as a first_fn and be done with the issue.

Related: OS#5020
Change-Id: Ie982caeb29f3ffd880b44e88a89b85ea3e6e6947
M src/osmo-bts-trx/sched_lchan_pdtch.c
1 file changed, 3 insertions(+), 3 deletions(-)

  git pull ssh:// refs/changes/22/23322/1

diff --git a/src/osmo-bts-trx/sched_lchan_pdtch.c b/src/osmo-bts-trx/sched_lchan_pdtch.c
index 665f643..5e61a1d 100644
--- a/src/osmo-bts-trx/sched_lchan_pdtch.c
+++ b/src/osmo-bts-trx/sched_lchan_pdtch.c
@@ -44,7 +44,7 @@
 	struct l1sched_ts *l1ts = l1sched_trx_get_ts(l1t, bi->tn);
 	struct l1sched_chan_state *chan_state = &l1ts->chan_state[chan];
 	sbit_t *burst, **bursts_p = &chan_state->ul_bursts;
-	uint32_t *first_fn = &chan_state->ul_first_fn;
+	uint32_t first_fn;
 	uint8_t *mask = &chan_state->ul_mask;
 	struct l1sched_meas_set meas_avg;
 	uint8_t l2[EGPRS_0503_MAX_BYTES];
@@ -70,7 +70,6 @@
 	if (bid == 0) {
 		memset(*bursts_p, 0, GSM0503_EGPRS_BURSTS_NBITS);
 		*mask = 0x0;
-		*first_fn = bi->fn;
 	/* update mask */
@@ -141,8 +140,9 @@
 	ber10k = compute_ber10k(n_bits_total, n_errors);
+	first_fn = GSM_TDMA_FN_SUB(bi->fn, 3);
 	return _sched_compose_ph_data_ind(l1t, bi->tn,
-					  *first_fn, chan, l2, rc,
+					  first_fn, chan, l2, rc,
 					  meas_avg.rssi, meas_avg.toa256,
 					  meas_avg.ci_cb, ber10k,

To view, visit
To unsubscribe, or for help writing mail filters, visit

Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: Ie982caeb29f3ffd880b44e88a89b85ea3e6e6947
Gerrit-Change-Number: 23322
Gerrit-PatchSet: 1
Gerrit-Owner: pespin <pespin at>
Gerrit-MessageType: newchange
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the gerrit-log mailing list