Review at https://gerrit.osmocom.org/2412
measurement: fix measurement computation
Timing advance is currently not taken into account when computing
the measurement results, this commit fixes that
Change-Id: I2e0dfd13b53e8aa2822985f12bf2985e683ab553
---
M include/osmo-bts/measurement.h
M src/common/measurement.c
2 files changed, 68 insertions(+), 0 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/12/2412/1
diff --git a/include/osmo-bts/measurement.h b/include/osmo-bts/measurement.h
index 2efe40f..87c8109 100644
--- a/include/osmo-bts/measurement.h
+++ b/include/osmo-bts/measurement.h
@@ -1,6 +1,9 @@
#ifndef OSMO_BTS_MEAS_H
#define OSMO_BTS_MEAS_H
+#define MEAS_MAX_TIMING_ADVANCE 63
+#define MEAS_MIN_TIMING_ADVANCE 0
+
int lchan_new_ul_meas(struct gsm_lchan *lchan, struct bts_ul_meas *ulm);
int trx_meas_check_compute(struct gsm_bts_trx *trx, uint32_t fn);
diff --git a/src/common/measurement.c b/src/common/measurement.c
index 79f6ae4..5613894 100644
--- a/src/common/measurement.c
+++ b/src/common/measurement.c
@@ -196,6 +196,53 @@
return 7;
}
+/* Update order TA at end of meas period */
+static void lchan_meas_update_ordered_TA(struct gsm_lchan *lchan,
+ int32_t taqb_sum)
+{
+ int32_t ms_timing_offset = 0;
+ uint8_t l1_info_valid;
+
+ l1_info_valid = lchan->meas.flags & LC_UL_M_F_L1_VALID;
+
+ if (l1_info_valid) {
+ DEBUGP(DMEAS,
+ "Update TA TimingOffset_Mean:%d, UL RX TA:%d, DL ordered
TA:%d, flags:%d \n",
+ taqb_sum, lchan->meas.l1_info[1], lchan->rqd_ta,
+ lchan->meas.flags);
+
+ ms_timing_offset =
+ taqb_sum + (lchan->meas.l1_info[1] - lchan->rqd_ta);
+
+ if (ms_timing_offset > 0) {
+ if (lchan->rqd_ta < MEAS_MAX_TIMING_ADVANCE) {
+ /* MS is moving away from BTS.
+ * So increment Ordered TA by 1 */
+ lchan->rqd_ta++;
+ }
+ } else if (ms_timing_offset < 0) {
+ if (lchan->rqd_ta > MEAS_MIN_TIMING_ADVANCE) {
+ /* MS is moving toward BTS. So decrement
+ * Ordered TA by 1 */
+ lchan->rqd_ta--;
+ }
+ } else {
+ /*MS is not moving so don't change Ordered TA */
+ }
+
+ DEBUGP(DMEAS,
+ "New Update TA--> TimingOff_diff:%d, UL RX TA:%d, DL
ordered TA:%d \n",
+ ms_timing_offset, lchan->meas.l1_info[1], lchan->rqd_ta);
+ } else {
+ /*Do Nothing */
+ }
+
+ /*Clear L1 INFO valid flag at Meas period end */
+ lchan->meas.flags &= ~LC_UL_M_F_L1_VALID;
+
+ return;
+}
+
int lchan_meas_check_compute(struct gsm_lchan *lchan, uint32_t fn)
{
struct gsm_meas_rep_unidir *mru;
@@ -206,6 +253,7 @@
int32_t taqb_sum = 0;
unsigned int num_meas_sub = 0;
int i;
+ int32_t ms_timing_offset = 0;
/* if measurement period is not complete, abort */
if (!is_meas_complete(ts_pchan(lchan->ts), lchan->ts->nr,
@@ -241,6 +289,9 @@
if (num_meas_sub) {
ber_sub_sum = ber_sub_sum / num_meas_sub;
irssi_sub_sum = irssi_sub_sum / num_meas_sub;
+ } else {
+ ber_sub_sum = ber_full_sum;
+ irssi_sub_sum = irssi_full_sum;
}
DEBUGP(DMEAS, "%s Computed TA(% 4dqb) BER-FULL(%2u.%02u%%),
RSSI-FULL(-%3udBm), "
@@ -249,6 +300,20 @@
ber_full_sum%100, irssi_full_sum, ber_sub_sum/100,
ber_sub_sum%100,
irssi_sub_sum);
+ /*Update ordered TA for DL SACCH L1 Header */
+ lchan_meas_update_ordered_TA(lchan, taqb_sum);
+
+ /* As per 3gpp spec-45.010 sec-1.2, An MS with a round trip
+ * propagation delay of P symbols, but with a timing advance of T
+ * symbols, the reported timing offset will be (P-T) quantized to
+ * the nearest symbol. */
+
+ ms_timing_offset = taqb_sum + (lchan->meas.l1_info[1] - lchan->rqd_ta);
+
+ /* 0->(-63), 1->(-62)... etc. */
+ lchan->meas.ms_timing_offset =
+ ms_timing_offset + MEAS_MAX_TIMING_ADVANCE;
+
/* store results */
mru = &lchan->meas.ul_res;
mru->full.rx_lev = dbm2rxlev((int)irssi_full_sum * -1);
--
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Gerrit-MessageType: newchange
Gerrit-Change-Id: I2e0dfd13b53e8aa2822985f12bf2985e683ab553
Gerrit-PatchSet: 1
Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Owner: dexter <pma...@sysmocom.de>
