Change in osmo-bts[master]: osmo-bts-trx: send dummy FACCH in the absense of RTP frames

fixeria gerrit-no-reply at lists.osmocom.org
Sun Jul 4 18:24:58 UTC 2021


fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/24846 )


Change subject: osmo-bts-trx: send dummy FACCH in the absense of RTP frames
......................................................................

osmo-bts-trx: send dummy FACCH in the absense of RTP frames

Change-Id: I868afecbcb6890f40c8f146e3ce00e836b794dd3
Related: OS#4823
---
M src/osmo-bts-trx/sched_lchan_tchf.c
M src/osmo-bts-trx/sched_lchan_tchh.c
2 files changed, 16 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/46/24846/1

diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 689925f..8e6298c 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -530,9 +530,16 @@
 		memset(*bursts_p + 464, 0, 464);
 	}
 
-	/* no message at all */
+	/* no message at all, send a dummy L2 frame on FACCH */
 	if (!msg_tch && !msg_facch) {
+		static const uint8_t dummy[GSM_MACBLOCK_LEN] = {
+			0x03, 0x03, 0x01, /* TODO: use randomized padding */
+			0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+			0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+		};
+
 		LOGL1SB(DL1P, LOGL_INFO, l1ts, br, "No TCH or FACCH prim for transmit.\n");
+		gsm0503_tch_fr_encode(*bursts_p, dummy, sizeof(dummy), 1);
 		goto send_burst;
 	}
 
diff --git a/src/osmo-bts-trx/sched_lchan_tchh.c b/src/osmo-bts-trx/sched_lchan_tchh.c
index 4f03bd1..bfebb66 100644
--- a/src/osmo-bts-trx/sched_lchan_tchh.c
+++ b/src/osmo-bts-trx/sched_lchan_tchh.c
@@ -417,9 +417,16 @@
 		}
 	}
 
-	/* no message at all */
+	/* no message at all, send a dummy L2 frame on FACCH */
 	if (!msg_tch && !msg_facch && !chan_state->dl_ongoing_facch) {
+		static const uint8_t dummy[GSM_MACBLOCK_LEN] = {
+			0x03, 0x03, 0x01, /* TODO: use randomized padding */
+			0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+			0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b, 0x2b,
+		};
+
 		LOGL1SB(DL1P, LOGL_INFO, l1ts, br, "No TCH or FACCH prim for transmit.\n");
+		gsm0503_tch_hr_encode(*bursts_p, dummy, sizeof(dummy));
 		goto send_burst;
 	}
 

-- 
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: I868afecbcb6890f40c8f146e3ce00e836b794dd3
Gerrit-Change-Number: 24846
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de>
Gerrit-MessageType: newchange
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