laforge submitted this change.
osmo-bts-trx: rx_tchf_fn(): do not treat AFS_SID_UPDATE as SUB frame
We have two similar values in enum gsm0503_amr_dtx_frames:
* AFS_SID_UPDATE - precursor of SID UPDATE,
* AFS_SID_UPDATE_CN - the actual SID UPDATE.
The former is internally used by libosmocoding to mark the current
frame as a precursor of the actual SID UPDATE frame - the later.
+---+---+---+---+---+---+---+---+
| _ | _ | _ | _ | a | b | c | d | AFS_SID_UPDATE
+---+---+---+---+---+---+---+---+
| a | b | c | d | _ | _ | _ | _ | AFS_SID_UPDATE_CN
+---+---+---+---+---+---+---+---+
^
|
| We're here.
Do not treat the precursor frames as a SUB frames, as they contain
no information (rc=-1) and usually have *expected* BER ~50%. This
fixes unexpected RXQUAL-SUB > 0 in the Uplink measurements during DTX.
Change-Id: I46f32bbbcb6284615d05b8703945c5ca4da55b92
Related: SYS#5853
---
M src/osmo-bts-trx/sched_lchan_tchf.c
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/osmo-bts-trx/sched_lchan_tchf.c b/src/osmo-bts-trx/sched_lchan_tchf.c
index 6a90327..067e31a 100644
--- a/src/osmo-bts-trx/sched_lchan_tchf.c
+++ b/src/osmo-bts-trx/sched_lchan_tchf.c
@@ -171,7 +171,11 @@
"Received AMR DTX frame (rc=%d, BER %d/%d): %s\n",
rc, n_errors, n_bits_total,
gsm0503_amr_dtx_frame_name(chan_state->amr_last_dtx));
- is_sub = 1;
+ /* ... except AFS_SID_UPDATE, which is in fact a precursor of
+ * the actual SID UPDATE frame (AFS_SID_UPDATE_CN) and only
+ * used internally by gsm0503_tch_afs_decode_dtx() */
+ if (chan_state->amr_last_dtx != AFS_SID_UPDATE)
+ is_sub = 1;
}
/* The occurrence of the following frames indicates that we
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