<p>fixeria has uploaded this change for <strong>review</strong>.</p><p><a href="https://gerrit.osmocom.org/c/osmo-bts/+/24776">View Change</a></p><pre style="font-family: monospace,monospace; white-space: pre-wrap;">osmo-bts-trx: implement BCCH carrier power reduction mode<br><br>The BCCH carrier (sometimes called C0) of a BTS shall maintain<br>discontinuous Downlink transmission at full power in order to<br>stay 'visible' to the mobile stations. Because of that, early<br>versions of 3GPP TS 45.008 prohibited BS power reduction on C0.<br><br>However, in the recent 3GPP TS 45.008 there is a feature called<br>'BCCH carrier power reduction operation'. This is a special<br>mode of operation, where the variation of RF level for some<br>timeslots is relaxed for the purpose of energy saving.<br><br>In BCCH carrier power reduction operation, for timeslots on the<br>C0 carrier, except timeslots carrying BCCH/CCCH, the output power<br>may be lower than the output power used for timeslots carrying<br>BCCH/CCCH. In this case the maximum allowed difference in output<br>power actually transmitted by the BTS is 6 dB.<br><br>The power reduction operation can be controlled by the BSC by<br>sending BS POWER CONTROL on the A-bis/RSL with the Channel Number<br>IE set to 0x80 (RSL_CHAN_BCCH). This makes osmo-bts reduce the<br>transmission power on inactive timeslots of the BCCH carrier.<br><br>This is a non-standard, Osmocom specific extension, so indicate<br>support of this feature to the BSC in the feature vector.<br><br>Change-Id: I3dcee6e910ccc61c5c63c728db9ea04327e2fc98<br>Depends: I69283b3f35988fc7a1a1dcf1a1ad3b67f08ec716<br>Related: SYS#4919<br>---<br>M include/osmo-bts/gsm_data.h<br>M src/common/rsl.c<br>M src/common/scheduler.c<br>M src/common/vty.c<br>M src/osmo-bts-trx/main.c<br>M src/osmo-bts-trx/scheduler_trx.c<br>6 files changed, 65 insertions(+), 0 deletions(-)<br><br></pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;">git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/76/24776/1</pre><pre style="font-family: monospace,monospace; white-space: pre-wrap;"><span>diff --git a/include/osmo-bts/gsm_data.h b/include/osmo-bts/gsm_data.h</span><br><span>index 808b48a..352f727 100644</span><br><span>--- a/include/osmo-bts/gsm_data.h</span><br><span>+++ b/include/osmo-bts/gsm_data.h</span><br><span>@@ -451,6 +451,9 @@</span><br><span> /* Training Sequence Set (range 0..3) */</span><br><span> uint8_t tsc_set;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* Actual BCCH carrier power reduction */</span><br><span style="color: hsl(120, 100%, 40%);">+ uint8_t bcch_power_red_db;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* Frequency hopping parameters (configured via OML) */</span><br><span> struct {</span><br><span> bool enabled;</span><br><span>diff --git a/src/common/rsl.c b/src/common/rsl.c</span><br><span>index 502e619..618a82d 100644</span><br><span>--- a/src/common/rsl.c</span><br><span>+++ b/src/common/rsl.c</span><br><span>@@ -2174,6 +2174,48 @@</span><br><span> return 0;</span><br><span> }</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+/* BCCH carrier power reduction */</span><br><span style="color: hsl(120, 100%, 40%);">+static int rsl_rx_bcch_pwr_ctrl(struct msgb *msg, const uint8_t red)</span><br><span style="color: hsl(120, 100%, 40%);">+{</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct gsm_lchan *lchan = msg->lchan;</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts_trx *c0 = lchan->ts->trx;</span><br><span style="color: hsl(120, 100%, 40%);">+ const uint8_t chan_nr = RSL_CHAN_BCCH;</span><br><span style="color: hsl(120, 100%, 40%);">+ unsigned int tn;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (c0->bts->c0 != c0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPTRX(c0, DRSL, LOGL_ERROR, "BCCH carrier power reduction "</span><br><span style="color: hsl(120, 100%, 40%);">+ "is not expected on this transceiver\n");</span><br><span style="color: hsl(120, 100%, 40%);">+ return rsl_tx_error_report(c0, RSL_ERR_PROTO, &chan_nr, NULL, msg);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ LOGPTRX(c0, DRSL, LOGL_NOTICE, "BCCH carrier power reduction: "</span><br><span style="color: hsl(120, 100%, 40%);">+ "%u dB (%s)\n", red, red ? "enabled" : "disabled");</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Timeslot 0 is always transmitting BCCH/CCCH */</span><br><span style="color: hsl(120, 100%, 40%);">+ c0->ts[0].bcch_power_red_db = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ for (tn = 1; tn < ARRAY_SIZE(c0->ts); tn++) {</span><br><span style="color: hsl(120, 100%, 40%);">+ struct gsm_bts_trx_ts *ts = &c0->ts[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct gsm_bts_trx_ts *next;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ts_pchan(ts) == GSM_PCHAN_CCCH)</span><br><span style="color: hsl(120, 100%, 40%);">+ ts->bcch_power_red_db = 0;</span><br><span style="color: hsl(120, 100%, 40%);">+ else</span><br><span style="color: hsl(120, 100%, 40%);">+ ts->bcch_power_red_db = red;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ts->bcch_power_red_db > 0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Next timeslot following this one */</span><br><span style="color: hsl(120, 100%, 40%);">+ next = &c0->ts[(tn + 1) % 8];</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* If BCCH/CCCH is following, limit to 2 dB */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ts_pchan(next) == GSM_PCHAN_CCCH)</span><br><span style="color: hsl(120, 100%, 40%);">+ ts->bcch_power_red_db = 2;</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ return 0;</span><br><span style="color: hsl(120, 100%, 40%);">+}</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* 8.4.16 BS POWER CONTROL */</span><br><span> static int rsl_rx_bs_pwr_ctrl(struct msgb *msg)</span><br><span> {</span><br><span>@@ -2197,6 +2239,10 @@</span><br><span> new = BS_POWER2DB(*TLVP_VAL(&tp, RSL_IE_BS_POWER));</span><br><span> old = lchan->bs_power_ctrl.current;</span><br><span> </span><br><span style="color: hsl(120, 100%, 40%);">+ /* Osmocom specific extension for BCCH carrier power reduction */</span><br><span style="color: hsl(120, 100%, 40%);">+ if (dch->chan_nr == RSL_CHAN_BCCH)</span><br><span style="color: hsl(120, 100%, 40%);">+ return rsl_rx_bcch_pwr_ctrl(msg, new);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span> /* 9.3.32 (TLV) BS Power Parameters IE (vendor specific) */</span><br><span> if ((ie = TLVP_GET(&tp, RSL_IE_BS_POWER_PARAM)) != NULL) {</span><br><span> struct gsm_power_ctrl_params *params = &lchan->bs_dpc_params;</span><br><span>@@ -3555,6 +3601,10 @@</span><br><span> case RSL_MT_OSMO_ETWS_CMD:</span><br><span> ret = rsl_rx_osmo_etws_cmd(trx, msg);</span><br><span> break;</span><br><span style="color: hsl(120, 100%, 40%);">+ /* Osmocom specific extension for BCCH carrier power reduction */</span><br><span style="color: hsl(120, 100%, 40%);">+ case RSL_MT_BS_POWER_CONTROL:</span><br><span style="color: hsl(120, 100%, 40%);">+ ret = rsl_rx_bs_pwr_ctrl(msg);</span><br><span style="color: hsl(120, 100%, 40%);">+ break;</span><br><span> default:</span><br><span> LOGPLCHAN(msg->lchan, DRSL, LOGL_NOTICE, "undefined RSL cchan msg_type 0x%02x\n",</span><br><span> cch->c.msg_type);</span><br><span>diff --git a/src/common/scheduler.c b/src/common/scheduler.c</span><br><span>index 93c1e85..ded77aa 100644</span><br><span>--- a/src/common/scheduler.c</span><br><span>+++ b/src/common/scheduler.c</span><br><span>@@ -1318,6 +1318,8 @@</span><br><span> /* BS Power reduction (in dB) per logical channel */</span><br><span> if (l1cs->lchan != NULL)</span><br><span> br->att = l1cs->lchan->bs_power_ctrl.current;</span><br><span style="color: hsl(120, 100%, 40%);">+ else</span><br><span style="color: hsl(120, 100%, 40%);">+ br->att = 0;</span><br><span> </span><br><span> /* encrypt */</span><br><span> if (br->burst_len && l1cs->dl_encr_algo) {</span><br><span>diff --git a/src/common/vty.c b/src/common/vty.c</span><br><span>index 039e929..3a794f3 100644</span><br><span>--- a/src/common/vty.c</span><br><span>+++ b/src/common/vty.c</span><br><span>@@ -1421,6 +1421,11 @@</span><br><span> vty_out(vty, "%s", VTY_NEWLINE);</span><br><span> vty_out(vty, " NM State: ");</span><br><span> net_dump_nmstate(vty, &ts->mo.nm_state);</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ if (ts->trx == ts->trx->bts->c0) {</span><br><span style="color: hsl(120, 100%, 40%);">+ vty_out(vty, " BCCH carrier power reduction: %u dB%s",</span><br><span style="color: hsl(120, 100%, 40%);">+ ts->bcch_power_red_db, VTY_NEWLINE);</span><br><span style="color: hsl(120, 100%, 40%);">+ }</span><br><span> }</span><br><span> </span><br><span> DEFUN(show_ts,</span><br><span>diff --git a/src/osmo-bts-trx/main.c b/src/osmo-bts-trx/main.c</span><br><span>index 7134939..be3715c 100644</span><br><span>--- a/src/osmo-bts-trx/main.c</span><br><span>+++ b/src/osmo-bts-trx/main.c</span><br><span>@@ -147,6 +147,7 @@</span><br><span> osmo_bts_set_feature(bts->features, BTS_FEAT_ACCH_REP);</span><br><span> osmo_bts_set_feature(bts->features, BTS_FEAT_MULTI_TSC);</span><br><span> osmo_bts_set_feature(bts->features, BTS_FEAT_VAMOS);</span><br><span style="color: hsl(120, 100%, 40%);">+ osmo_bts_set_feature(bts->features, BTS_FEAT_BCCH_POWER_RED);</span><br><span> </span><br><span> bts_internal_flag_set(bts, BTS_INTERNAL_FLAG_MEAS_PAYLOAD_COMB);</span><br><span> </span><br><span>diff --git a/src/osmo-bts-trx/scheduler_trx.c b/src/osmo-bts-trx/scheduler_trx.c</span><br><span>index ef50e8d..6fd5d1a 100644</span><br><span>--- a/src/osmo-bts-trx/scheduler_trx.c</span><br><span>+++ b/src/osmo-bts-trx/scheduler_trx.c</span><br><span>@@ -195,9 +195,13 @@</span><br><span> for (tn = 0; tn < ARRAY_SIZE(trx->ts); tn++) {</span><br><span> struct phy_instance *pinst = bts->c0->pinst;</span><br><span> struct trx_dl_burst_req *br = &pinst->u.osmotrx.br[tn];</span><br><span style="color: hsl(120, 100%, 40%);">+ const struct gsm_bts_trx_ts *ts = &bts->c0->ts[tn];</span><br><span> </span><br><span> memcpy(br->burst, _sched_dummy_burst, GSM_BURST_LEN);</span><br><span> br->burst_len = GSM_BURST_LEN;</span><br><span style="color: hsl(120, 100%, 40%);">+</span><br><span style="color: hsl(120, 100%, 40%);">+ /* BCCH carrier power reduction for this timeslot */</span><br><span style="color: hsl(120, 100%, 40%);">+ br->att = ts->bcch_power_red_db;</span><br><span> }</span><br><span> }</span><br><span> </span><br><span></span><br></pre><p>To view, visit <a href="https://gerrit.osmocom.org/c/osmo-bts/+/24776">change 24776</a>. To unsubscribe, or for help writing mail filters, visit <a href="https://gerrit.osmocom.org/settings">settings</a>.</p><div itemscope itemtype="http://schema.org/EmailMessage"><div itemscope itemprop="action" itemtype="http://schema.org/ViewAction"><link itemprop="url" href="https://gerrit.osmocom.org/c/osmo-bts/+/24776"/><meta itemprop="name" content="View Change"/></div></div>
<div style="display:none"> Gerrit-Project: osmo-bts </div>
<div style="display:none"> Gerrit-Branch: master </div>
<div style="display:none"> Gerrit-Change-Id: I3dcee6e910ccc61c5c63c728db9ea04327e2fc98 </div>
<div style="display:none"> Gerrit-Change-Number: 24776 </div>
<div style="display:none"> Gerrit-PatchSet: 1 </div>
<div style="display:none"> Gerrit-Owner: fixeria <vyanitskiy@sysmocom.de> </div>
<div style="display:none"> Gerrit-MessageType: newchange </div>