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dexter gerrit-no-reply at lists.osmocom.orgdexter has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/21024 )
Change subject: sched_lchan_tchh: redirect FACCH measurements via BFI TCH indication
......................................................................
sched_lchan_tchh: redirect FACCH measurements via BFI TCH indication
A FACCH block is spread over 6 frames. This means that two TCH blocks
are skipped in favor of the FACCH. In speach mode the missing TCH blocks
will emit a TCH indication anyway. Those indications carry no
measurement results. Unfortunately the anpredictable behaviour of the
FACCH and the asymetric block sizes create an uneaven stream of
measurement results which makes processing of the measurement results
rather difficult. However, the processing of the measurement results can
be simplified when we even out the measurement results by redirecting
the FACCH measurements via BFI TCH indications.
Change-Id: Ib1f0dfe4cb03a356254503abf51e9f27d0dd2179
Related: OS#4799
---
M include/osmo-bts/scheduler.h
M src/osmo-bts-trx/sched_lchan_tchh.c
2 files changed, 37 insertions(+), 4 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/24/21024/1
diff --git a/include/osmo-bts/scheduler.h b/include/osmo-bts/scheduler.h
index 6bb0b9b..2536609 100644
--- a/include/osmo-bts/scheduler.h
+++ b/include/osmo-bts/scheduler.h
@@ -114,6 +114,7 @@
/* TCH/H */
uint8_t dl_ongoing_facch; /* FACCH/H on downlink */
uint8_t ul_ongoing_facch; /* FACCH/H on uplink */
+ struct l1sched_meas_set meas_avg_facch; /* Last FACCH/H measurement sample */
/* encryption */
int ul_encr_algo; /* A5/x encry algo downlink */
diff --git a/src/osmo-bts-trx/sched_lchan_tchh.c b/src/osmo-bts-trx/sched_lchan_tchh.c
index c7dac70..85c8a25 100644
--- a/src/osmo-bts-trx/sched_lchan_tchh.c
+++ b/src/osmo-bts-trx/sched_lchan_tchh.c
@@ -71,6 +71,7 @@
uint16_t ber10k;
uint8_t is_sub = 0;
uint8_t ft;
+ bool redirect_facch_meas = false;
/* If handover RACH detection is turned on, treat this burst as an Access Burst.
* Handle NOPE.ind as usually to ensure proper Uplink measurement reporting. */
@@ -128,6 +129,11 @@
* was decoded (see below), now send the second one. */
ber10k = 0;
memset(&meas_avg, 0, sizeof(meas_avg));
+ /* Redirect FACCH measurement values via BFI TCH indications.
+ * this is only valid for SPEECH mode, since in SIGNALLING no
+ * BFI TCH indications are generated. */
+ if (rsl_cmode == RSL_CMOD_SPD_SPEECH)
+ redirect_facch_meas = 1;
goto bfi;
}
@@ -262,6 +268,17 @@
fn_begin = gsm0502_fn_remap(bi->fn, FN_REMAP_FACCH_H0);
else
fn_begin = gsm0502_fn_remap(bi->fn, FN_REMAP_FACCH_H1);
+
+ /* (see also note above). We backup the measurement values we received
+ * with the FACCH/H, then we invalidate the measurement value, so that
+ * the higher layers will not count the measurement value we hand over
+ * with the FACCH DATA indication. */
+ if (rsl_cmode == RSL_CMOD_SPD_SPEECH) {
+ memcpy(&chan_state->meas_avg_facch, &meas_avg, sizeof(chan_state->meas_avg_facch));
+ meas_avg.rssi = 0;
+ redirect_facch_meas = 1;
+ }
+
_sched_compose_ph_data_ind(l1t, bi->tn, fn_begin, chan,
tch_data + amr, GSM_MACBLOCK_LEN,
meas_avg.rssi, meas_avg.toa256,
@@ -326,10 +343,25 @@
fn_begin = gsm0502_fn_remap(bi->fn, FN_REMAP_TCH_H0);
else
fn_begin = gsm0502_fn_remap(bi->fn, FN_REMAP_TCH_H1);
- return _sched_compose_tch_ind(l1t, bi->tn, fn_begin, chan, tch_data, rc,
- /* FIXME: what should we use for BFI here? */
- bfi_flag ? bi->toa256 : meas_avg.toa256, ber10k,
- bfi_flag ? bi->rssi : meas_avg.rssi, is_sub);
+
+ /* Use measurement values from the last FACCH transmission instead of
+ * the current one. This is only done when a previous FACCH transmission
+ * took out two TCH voice blocks. To maintain a constant stream of
+ * measurement values we redirect the measurement values we have
+ * received with the FACCH to the two replacement BFI TCH indications. */
+ if(redirect_facch_meas)
+ memcpy(&meas_avg, &chan_state->meas_avg_facch, sizeof(chan_state->meas_avg_facch));
+
+ rc = _sched_compose_tch_ind(l1t, bi->tn, fn_begin, chan, tch_data, rc,
+ /* FIXME: what should we use for BFI here? */
+ bfi_flag ? bi->toa256 : meas_avg.toa256, ber10k,
+ bfi_flag ? bi->rssi : meas_avg.rssi, is_sub);
+
+ /* Invalidate the cached measurement value from the last FACCH. */
+ if (redirect_facch_meas && chan_state->ul_ongoing_facch == 0)
+ chan_state->meas_avg_facch.rssi = 0;
+
+ return rc;
}
/* common section for generation of TCH bursts (TCH/H and TCH/F).
--
To view, visit https://gerrit.osmocom.org/c/osmo-bts/+/21024
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: Ib1f0dfe4cb03a356254503abf51e9f27d0dd2179
Gerrit-Change-Number: 21024
Gerrit-PatchSet: 1
Gerrit-Owner: dexter <pmaier at sysmocom.de>
Gerrit-MessageType: newchange
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