Change in osmo-bsc[master]: handover: apply meas report BS Power to RXLEV, fix ho oscillation

laforge gerrit-no-reply at lists.osmocom.org
Sat Jun 5 14:35:17 UTC 2021


laforge has submitted this change. ( https://gerrit.osmocom.org/c/osmo-bsc/+/24425 )

Change subject: handover: apply meas report BS Power to RXLEV, fix ho oscillation
......................................................................

handover: apply meas report BS Power to RXLEV, fix ho oscillation

This fixes handover oscillation in the presence of power reduction on
the downlink: apply the reduced power to the cell's RXLEV in order to
not rate the current cell as weaker than it actually is.

Related: SYS#5339
Change-Id: Ifcf59964b5e2d550d79e4ba14d90962808f79dae
---
M src/osmo-bsc/meas_rep.c
M tests/handover/test_bs_power.ho_vty
2 files changed, 9 insertions(+), 10 deletions(-)

Approvals:
  laforge: Looks good to me, approved
  fixeria: Looks good to me, but someone else must approve
  Jenkins Builder: Verified



diff --git a/src/osmo-bsc/meas_rep.c b/src/osmo-bsc/meas_rep.c
index 73d9a1f..9b2fca0 100644
--- a/src/osmo-bsc/meas_rep.c
+++ b/src/osmo-bsc/meas_rep.c
@@ -31,11 +31,15 @@
 	case MEAS_REP_DL_RXLEV_FULL:
 		if (!(rep->flags & MEAS_REP_F_DL_VALID))
 			return -EINVAL;
-		return rep->dl.full.rx_lev;
+		/* Add BS Power value to rxlev: improve the RXLEV value by the amount of power that the BTS is reducing
+		 * transmission. Note that bs_power is coded as dB/2, a positive value indicating the amount of power reduction
+		 * on the downlink; rxlev is coded in dB, where a higher number means stronger signal. */
+		return rep->dl.full.rx_lev + (rep->bs_power * 2);
 	case MEAS_REP_DL_RXLEV_SUB:
 		if (!(rep->flags & MEAS_REP_F_DL_VALID))
 			return -EINVAL;
-		return rep->dl.sub.rx_lev;
+		/* Apply BS Power as explained above */
+		return rep->dl.sub.rx_lev + (rep->bs_power * 2);
 	case MEAS_REP_DL_RXQUAL_FULL:
 		if (!(rep->flags & MEAS_REP_F_DL_VALID))
 			return -EINVAL;
diff --git a/tests/handover/test_bs_power.ho_vty b/tests/handover/test_bs_power.ho_vty
index 2c68d57..5d8c278 100644
--- a/tests/handover/test_bs_power.ho_vty
+++ b/tests/handover/test_bs_power.ho_vty
@@ -6,11 +6,6 @@
 set-ts-use trx 0 0 states        *    TCH/F -     -     -     -     -     *
 
 meas-rep repeat 10 bspower 20 lchan 0 0 1 0 rxlev 20 rxqual 0 ta 0 neighbors 30
-# FAIL: there should be no handover, because the bspower reduction of 20 with an rxlev of 20 (= 40) is stronger than the
-# neighbor at 30. But since osmo-bsc fails to take the BS Power into account, it hands over to the neighbor.
-#expect-no-chan
-expect-ho from lchan 0 0 1 0 to lchan 1 0 1 0
-
-# When the neighbor then reports the stronger original cell, we get handover oscillation
-meas-rep repeat 10 bspower 0 lchan 1 0 1 0 rxlev 30 rxqual 0 ta 0 neighbors 40
-expect-ho from lchan 1 0 1 0 to lchan 0 0 1 0
+# there should be no handover, because the bspower reduction of 20 with an rxlev of 20 (= 40) is stronger than the
+# neighbor at 30.
+expect-no-chan

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Gerrit-Project: osmo-bsc
Gerrit-Branch: master
Gerrit-Change-Id: Ifcf59964b5e2d550d79e4ba14d90962808f79dae
Gerrit-Change-Number: 24425
Gerrit-PatchSet: 7
Gerrit-Owner: neels <nhofmeyr at sysmocom.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de>
Gerrit-Reviewer: laforge <laforge at osmocom.org>
Gerrit-CC: pespin <pespin at sysmocom.de>
Gerrit-MessageType: merged
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