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fixeria gerrit-no-reply at lists.osmocom.orgfixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/24776 ) Change subject: osmo-bts-trx: implement BCCH carrier power reduction mode ...................................................................... osmo-bts-trx: implement BCCH carrier power reduction mode 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, in the recent 3GPP TS 45.008 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. The power reduction operation can be controlled by the BSC by sending BS POWER CONTROL on the A-bis/RSL with the Channel Number IE set to 0x80 (RSL_CHAN_BCCH). This makes osmo-bts reduce the transmission power on inactive timeslots of the BCCH carrier. This is a non-standard, Osmocom specific extension, so indicate support of this feature to the BSC in the feature vector. Change-Id: I3dcee6e910ccc61c5c63c728db9ea04327e2fc98 Depends: I69283b3f35988fc7a1a1dcf1a1ad3b67f08ec716 Related: SYS#4919 --- M include/osmo-bts/gsm_data.h M src/common/rsl.c M src/common/scheduler.c M src/common/vty.c M src/osmo-bts-trx/main.c M src/osmo-bts-trx/scheduler_trx.c 6 files changed, 65 insertions(+), 0 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/76/24776/1 diff --git a/include/osmo-bts/gsm_data.h b/include/osmo-bts/gsm_data.h index 808b48a..352f727 100644 --- a/include/osmo-bts/gsm_data.h +++ b/include/osmo-bts/gsm_data.h @@ -451,6 +451,9 @@ /* Training Sequence Set (range 0..3) */ uint8_t tsc_set; + /* Actual BCCH carrier power reduction */ + uint8_t bcch_power_red_db; + /* Frequency hopping parameters (configured via OML) */ struct { bool enabled; diff --git a/src/common/rsl.c b/src/common/rsl.c index 502e619..618a82d 100644 --- a/src/common/rsl.c +++ b/src/common/rsl.c @@ -2174,6 +2174,48 @@ return 0; } +/* BCCH carrier power reduction */ +static int rsl_rx_bcch_pwr_ctrl(struct msgb *msg, const uint8_t red) +{ + const struct gsm_lchan *lchan = msg->lchan; + struct gsm_bts_trx *c0 = lchan->ts->trx; + const uint8_t chan_nr = RSL_CHAN_BCCH; + unsigned int tn; + + if (c0->bts->c0 != c0) { + LOGPTRX(c0, DRSL, LOGL_ERROR, "BCCH carrier power reduction " + "is not expected on this transceiver\n"); + return rsl_tx_error_report(c0, RSL_ERR_PROTO, &chan_nr, NULL, msg); + } + + LOGPTRX(c0, DRSL, LOGL_NOTICE, "BCCH carrier power reduction: " + "%u dB (%s)\n", red, red ? "enabled" : "disabled"); + + /* Timeslot 0 is always transmitting BCCH/CCCH */ + c0->ts[0].bcch_power_red_db = 0; + + for (tn = 1; tn < ARRAY_SIZE(c0->ts); tn++) { + struct gsm_bts_trx_ts *ts = &c0->ts[tn]; + const struct gsm_bts_trx_ts *next; + + if (ts_pchan(ts) == GSM_PCHAN_CCCH) + ts->bcch_power_red_db = 0; + else + ts->bcch_power_red_db = red; + + if (ts->bcch_power_red_db > 0) { + /* Next timeslot following this one */ + next = &c0->ts[(tn + 1) % 8]; + + /* If BCCH/CCCH is following, limit to 2 dB */ + if (ts_pchan(next) == GSM_PCHAN_CCCH) + ts->bcch_power_red_db = 2; + } + } + + return 0; +} + /* 8.4.16 BS POWER CONTROL */ static int rsl_rx_bs_pwr_ctrl(struct msgb *msg) { @@ -2197,6 +2239,10 @@ new = BS_POWER2DB(*TLVP_VAL(&tp, RSL_IE_BS_POWER)); old = lchan->bs_power_ctrl.current; + /* Osmocom specific extension for BCCH carrier power reduction */ + if (dch->chan_nr == RSL_CHAN_BCCH) + return rsl_rx_bcch_pwr_ctrl(msg, new); + /* 9.3.32 (TLV) BS Power Parameters IE (vendor specific) */ if ((ie = TLVP_GET(&tp, RSL_IE_BS_POWER_PARAM)) != NULL) { struct gsm_power_ctrl_params *params = &lchan->bs_dpc_params; @@ -3555,6 +3601,10 @@ case RSL_MT_OSMO_ETWS_CMD: ret = rsl_rx_osmo_etws_cmd(trx, msg); break; + /* Osmocom specific extension for BCCH carrier power reduction */ + case RSL_MT_BS_POWER_CONTROL: + ret = rsl_rx_bs_pwr_ctrl(msg); + break; default: LOGPLCHAN(msg->lchan, DRSL, LOGL_NOTICE, "undefined RSL cchan msg_type 0x%02x\n", cch->c.msg_type); diff --git a/src/common/scheduler.c b/src/common/scheduler.c index 93c1e85..ded77aa 100644 --- a/src/common/scheduler.c +++ b/src/common/scheduler.c @@ -1318,6 +1318,8 @@ /* BS Power reduction (in dB) per logical channel */ if (l1cs->lchan != NULL) br->att = l1cs->lchan->bs_power_ctrl.current; + else + br->att = 0; /* encrypt */ if (br->burst_len && l1cs->dl_encr_algo) { diff --git a/src/common/vty.c b/src/common/vty.c index 039e929..3a794f3 100644 --- a/src/common/vty.c +++ b/src/common/vty.c @@ -1421,6 +1421,11 @@ vty_out(vty, "%s", VTY_NEWLINE); vty_out(vty, " NM State: "); net_dump_nmstate(vty, &ts->mo.nm_state); + + if (ts->trx == ts->trx->bts->c0) { + vty_out(vty, " BCCH carrier power reduction: %u dB%s", + ts->bcch_power_red_db, VTY_NEWLINE); + } } DEFUN(show_ts, diff --git a/src/osmo-bts-trx/main.c b/src/osmo-bts-trx/main.c index 7134939..be3715c 100644 --- a/src/osmo-bts-trx/main.c +++ b/src/osmo-bts-trx/main.c @@ -147,6 +147,7 @@ osmo_bts_set_feature(bts->features, BTS_FEAT_ACCH_REP); osmo_bts_set_feature(bts->features, BTS_FEAT_MULTI_TSC); osmo_bts_set_feature(bts->features, BTS_FEAT_VAMOS); + osmo_bts_set_feature(bts->features, BTS_FEAT_BCCH_POWER_RED); bts_internal_flag_set(bts, BTS_INTERNAL_FLAG_MEAS_PAYLOAD_COMB); diff --git a/src/osmo-bts-trx/scheduler_trx.c b/src/osmo-bts-trx/scheduler_trx.c index ef50e8d..6fd5d1a 100644 --- a/src/osmo-bts-trx/scheduler_trx.c +++ b/src/osmo-bts-trx/scheduler_trx.c @@ -195,9 +195,13 @@ for (tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) { struct phy_instance *pinst = bts->c0->pinst; struct trx_dl_burst_req *br = &pinst->u.osmotrx.br[tn]; + const struct gsm_bts_trx_ts *ts = &bts->c0->ts[tn]; memcpy(br->burst, _sched_dummy_burst, GSM_BURST_LEN); br->burst_len = GSM_BURST_LEN; + + /* BCCH carrier power reduction for this timeslot */ + br->att = ts->bcch_power_red_db; } } -- To view, visit https://gerrit.osmocom.org/c/osmo-bts/+/24776 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-bts Gerrit-Branch: master Gerrit-Change-Id: I3dcee6e910ccc61c5c63c728db9ea04327e2fc98 Gerrit-Change-Number: 24776 Gerrit-PatchSet: 1 Gerrit-Owner: fixeria <vyanitskiy at sysmocom.de> Gerrit-MessageType: newchange -------------- next part -------------- An HTML attachment was scrubbed... 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