diff options
| author | Vadim Yanitskiy <vyanitskiy@sysmocom.de> | 2021-06-21 21:55:46 +0200 |
|---|---|---|
| committer | fixeria <vyanitskiy@sysmocom.de> | 2021-07-05 12:17:59 +0000 |
| commit | ced29cf94cc0bfa82cf62a7b1fa48202145f3fb6 (patch) | |
| tree | 5bab9715c73cd5d95098ad3d3182d986fa57be9b /src/osmo-bsc/bts.c | |
| parent | a4de0fea51547b431fcbc7e143a3b05e4db69d03 (diff) | |
power_control: implement BCCH carrier power reduction operation
The BCCH carrier (sometimes called C0) of a BTS shall maintain
discontinuous Downlink transmission at full power in order to
stay 'visible' to the mobile stations. Because of that, early
versions of 3GPP TS 45.008 prohibited BS power reduction on C0.
However, starting from version 13.0.0 (2015-11) there is a feature
called 'BCCH carrier power reduction operation'. This is a special
mode of operation, where the variation of RF level for some
timeslots is relaxed for the purpose of energy saving.
In BCCH carrier power reduction operation, for timeslots on the
C0 carrier, except timeslots carrying BCCH/CCCH, the output power
may be lower than the output power used for timeslots carrying
BCCH/CCCH. In this case the maximum allowed difference in output
power actually transmitted by the BTS is 6 dB.
Introduce a VTY command to turn on and off the BCCH carrier power
reduction operation. Also introduce a CTRL command. On the
A-bis/RSL, abuse the BS POWER CONTROL message by setting
the Channel Number IE to 0x80 (RSL_CHAN_BCCH).
Currently, only osmo-bts-trx is supported. A value greater than
zero makes it reduce the power on *inactive* timeslots of the
BCCH carrier. Sending zero disables the BCCH power reduction
mode completely.
For more details, see 3GPP TS 45.008, section 7.1, and 3GPP TR 45.926.
Change-Id: I047fce33d4d3e4c569dd006ba17858467a2f4783
Related: SYS#4919
Diffstat (limited to 'src/osmo-bsc/bts.c')
| -rw-r--r-- | src/osmo-bsc/bts.c | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/src/osmo-bsc/bts.c b/src/osmo-bsc/bts.c index b64890fae..c1f09ff07 100644 --- a/src/osmo-bsc/bts.c +++ b/src/osmo-bsc/bts.c @@ -1,5 +1,5 @@ /* (C) 2008-2018 by Harald Welte <laforge@gnumonks.org> - * (C) 2020 by sysmocom s.f.m.c. GmbH <info@sysmocom.de> + * (C) 2021 by sysmocom s.f.m.c. GmbH <info@sysmocom.de> * * All Rights Reserved * @@ -747,6 +747,24 @@ int gsm_bts_set_system_infos(struct gsm_bts *bts) return 0; } +int gsm_bts_set_c0_power_red(struct gsm_bts *bts, const uint8_t red) +{ + int rc; + + if (!osmo_bts_has_feature(&bts->features, BTS_FEAT_BCCH_POWER_RED)) + return -ENOTSUP; + if (bts->model->power_ctrl_set_c0_power_red == NULL) + return -ENOTSUP; + + rc = bts->model->power_ctrl_set_c0_power_red(bts, red); + if (rc != 0) + return rc; + + bts->c0_max_power_red_db = red; + + return 0; +} + const struct rate_ctr_desc bts_ctr_description[] = { [BTS_CTR_CHREQ_TOTAL] = \ { "chreq:total", |