diff options
| -rw-r--r-- | doc/manuals/chapters/power_control.adoc | 81 | ||||
| -rw-r--r-- | include/osmocom/bsc/bts.h | 7 | ||||
| -rw-r--r-- | src/osmo-bsc/bsc_ctrl_commands.c | 49 | ||||
| -rw-r--r-- | src/osmo-bsc/bsc_vty.c | 42 | ||||
| -rw-r--r-- | src/osmo-bsc/bts.c | 20 | ||||
| -rw-r--r-- | src/osmo-bsc/bts_osmobts.c | 33 | ||||
| -rw-r--r-- | tests/osmo-bsc.vty | 4 |
7 files changed, 235 insertions, 1 deletions
diff --git a/doc/manuals/chapters/power_control.adoc b/doc/manuals/chapters/power_control.adoc index 4c1a275b8..bb87c850c 100644 --- a/doc/manuals/chapters/power_control.adoc +++ b/doc/manuals/chapters/power_control.adoc @@ -327,3 +327,84 @@ network // TODO: Document other power control parameters: // OsmoBSC(config-net-bts)# ms max power <0-40> // OsmoBSC(config-net-bts-trx)# max_power_red <0-100> + +=== BCCH carrier power reduction operation + +According to 3GPP TS 45.008, section 7.1, the BCCH carrier (sometimes called C0) of +a BTS shall maintain continuous Downlink transmission at full power in order to +stay "visible" to the mobile stations. Because of that, early versions of this 3GPP +document prohibited BS power reduction on C0. However, a new feature was introduced +in version 13.0.0 (2015-11) - "BCCH carrier power reduction operation". + +This is a special mode of operation, in which the variation of RF power level for +some timeslots is relaxed for the purpose of energy saving. In other words, the +output power on some timeslots, except the timeslot(s) carrying BCCH/CCCH, can be +lower than the full power. In this case the maximum allowed difference is 6 dB. + +Of course, energy saving comes at a price and has impacts to the network KPI. In +particular, it does negatively affect cell reselection performance and does increase +handover failure and call drop rates. This is why BCCH carrier power reduction +operation mode is not enabled by default. More information on potential impact +and the simulation results can be found in 3GPP TR 45.926. + +==== Supported BTS models + +At the time of writing this manual, the only BTS model that can be instructed to +enter or leave the BCCH power reduction mode is osmo-bts-trx. Support for other +BTS vendors/models may be added in the future. + +TIP: If you're using OsmoBTS, make sure that it reports feature #021 "BCCH carrier +power reduction mode" in the feature vector. This can be checked by issuing +`show bts` command in OsmoBSC's VTY interface. + +==== Managing BCCH carrier power reduction + +The BCCH carrier power reduction can be controlled via the CTRL and VTY interfaces. +There is currently no logic in OsmoBSC for automatic activation and deactivation +of this mode, so it's up to the network operator (or an external monitoring suite) +when and depending on which factors to toggle it. Setting a value greater than +zero enables the BCCH power reduction mode; setting zero disables it completely. + +.Example: Activating BCCH carrier power reduction via the VTY +---- +OsmoBSC> enable +OsmoBSC# bts 0 <1> c0-power-reduction ? + <0-6> Power reduction value (in dB, even numbers only) +OsmoBSC# bts 0 <1> c0-power-reduction 4 <2> +---- +<1> BTS number for which to activate BCCH carrier power reduction +<2> Maximum BCCH carrier power reduction (in 2 dB steps, 4 dB in this example) + +.Example: Activating BCCH carrier power reduction via the CTRL +---- +$ osmo_ctrl.py \ + --host 127.0.0.1 <1> -p 4249 \ + --set "bts.0.c0-power-reduction" 4 <2> +---- +<1> Remote address of the host running osmo-bsc (localhost in this example) +<2> Maximum BCCH carrier power reduction (in 2 dB steps, 4 dB in this example) + +Once activated, it's possible to introspect the current maximum reduction value: + +.Example: Checking BCCH carrier power reduction state via the VTY +---- +OsmoBSC> enable +OsmoBSC# show bts 0 <1> +BTS 0 is of osmo-bts type in band DCS1800, has CI 0 LAC 1, BSIC 63 (NCC=7, BCC=7) and 2 TRX + Description: (null) + ARFCNs: 751 753 + BCCH carrier power reduction (maximum): 4 dB <2> + ... +---- +<1> BTS number for which to show BCCH carrier power reduction state +<2> Maximum BCCH carrier power reduction currently applied + +.Example: Checking BCCH carrier power reduction state via the CTRL +---- +$ osmo_ctrl.py \ + --host 127.0.0.1 <1> -p 4249 \ + --get "bts.0.c0-power-reduction" +Got message: b'GET_REPLY 3652121201381481804 bts.0.c0-power-reduction 4 <2>' +---- +<1> Remote address of the host running osmo-bsc (localhost in this example) +<2> Maximum BCCH carrier power reduction currently applied diff --git a/include/osmocom/bsc/bts.h b/include/osmocom/bsc/bts.h index 49691e023..65c3be511 100644 --- a/include/osmocom/bsc/bts.h +++ b/include/osmocom/bsc/bts.h @@ -236,6 +236,8 @@ struct gsm_bts_model { int (*power_ctrl_enc_rsl_params)(struct msgb *msg, const struct gsm_power_ctrl_params *cp); /* (Optional) function for sending default MS/BS Power Control paramaters */ int (*power_ctrl_send_def_params)(const struct gsm_bts_trx *trx); + /* (Optional) function for toggling BCCH carrier power reduction operation */ + int (*power_ctrl_set_c0_power_red)(const struct gsm_bts *bts, const uint8_t red); void (*config_write_bts)(struct vty *vty, struct gsm_bts *bts); void (*config_write_trx)(struct vty *vty, struct gsm_bts_trx *trx); @@ -543,6 +545,9 @@ struct gsm_bts { struct gsm_power_ctrl_params ms_power_ctrl; struct gsm_power_ctrl_params bs_power_ctrl; + /* Maximum BCCH carrier power reduction */ + uint8_t c0_max_power_red_db; + /* Interference Measurement Parameters */ struct gsm_interf_meas_params interf_meas_params; @@ -691,6 +696,8 @@ int bts_count_free_ts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan); int gsm_bts_set_system_infos(struct gsm_bts *bts); +int gsm_bts_set_c0_power_red(struct gsm_bts *bts, const uint8_t red); + int gsm_bts_model_register(struct gsm_bts_model *model); struct gsm_bts_model *bts_model_find(enum gsm_bts_type type); diff --git a/src/osmo-bsc/bsc_ctrl_commands.c b/src/osmo-bsc/bsc_ctrl_commands.c index 15f553645..be83b1b49 100644 --- a/src/osmo-bsc/bsc_ctrl_commands.c +++ b/src/osmo-bsc/bsc_ctrl_commands.c @@ -550,6 +550,54 @@ static int set_trx_max_power(struct ctrl_cmd *cmd, void *_data) } CTRL_CMD_DEFINE(trx_max_power, "max-power-reduction"); +static int verify_bts_c0_power_red(struct ctrl_cmd *cmd, const char *value, void *_data) +{ + const int red = atoi(value); + + if (red < 0 || red > 6) { + cmd->reply = "Value is out of range"; + return 1; + } else if (red % 2 != 0) { + cmd->reply = "Value must be even"; + return 1; + } + + return 0; +} + +static int get_bts_c0_power_red(struct ctrl_cmd *cmd, void *data) +{ + const struct gsm_bts *bts = cmd->node; + + cmd->reply = talloc_asprintf(cmd, "%u", bts->c0_max_power_red_db); + if (!cmd->reply) { + cmd->reply = "OOM."; + return CTRL_CMD_ERROR; + } + + return CTRL_CMD_REPLY; +} + +static int set_bts_c0_power_red(struct ctrl_cmd *cmd, void *data) +{ + struct gsm_bts *bts = cmd->node; + const int red = atoi(cmd->value); + int rc; + + rc = gsm_bts_set_c0_power_red(bts, red); + if (rc == -ENOTSUP) { + cmd->reply = "BCCH carrier power reduction is not supported"; + return CTRL_CMD_ERROR; + } else if (rc != 0) { + cmd->reply = "Failed to enable BCCH carrier power reduction"; + return CTRL_CMD_ERROR; + } + + return get_bts_c0_power_red(cmd, data); +} + +CTRL_CMD_DEFINE(bts_c0_power_red, "c0-power-reduction"); + int bsc_base_ctrl_cmds_install(void) { int rc = 0; @@ -571,6 +619,7 @@ int bsc_base_ctrl_cmds_install(void) rc |= ctrl_cmd_install(CTRL_NODE_BTS, &cmd_bts_oml_up); rc |= ctrl_cmd_install(CTRL_NODE_BTS, &cmd_bts_gprs_mode); rc |= ctrl_cmd_install(CTRL_NODE_BTS, &cmd_bts_rf_state); + rc |= ctrl_cmd_install(CTRL_NODE_BTS, &cmd_bts_c0_power_red); rc |= ctrl_cmd_install(CTRL_NODE_TRX, &cmd_trx_max_power); rc |= ctrl_cmd_install(CTRL_NODE_TRX, &cmd_trx_arfcn); diff --git a/src/osmo-bsc/bsc_vty.c b/src/osmo-bsc/bsc_vty.c index 7207341a1..efa59d3e1 100644 --- a/src/osmo-bsc/bsc_vty.c +++ b/src/osmo-bsc/bsc_vty.c @@ -444,6 +444,8 @@ static void bts_dump_vty(struct vty *vty, struct gsm_bts *bts) if (strnlen(bts->pcu_version, MAX_VERSION_LENGTH)) vty_out(vty, " PCU version %s connected%s", bts->pcu_version, VTY_NEWLINE); + vty_out(vty, " BCCH carrier power reduction (maximum): %u dB%s", + bts->c0_max_power_red_db, VTY_NEWLINE); vty_out(vty, " MS Max power: %u dBm%s", bts->ms_max_power, VTY_NEWLINE); vty_out(vty, " Minimum Rx Level for Access: %i dBm%s", rxlev2dbm(bts->si_common.cell_sel_par.rxlev_acc_min), @@ -6020,6 +6022,45 @@ DEFUN(bts_resend_power_ctrl_params, return CMD_SUCCESS; } +DEFUN(bts_c0_power_red, + bts_c0_power_red_cmd, + "bts <0-255> c0-power-reduction <0-6>", + "BTS Specific Commands\n" BTS_NR_STR + "BCCH carrier power reduction operation\n" + "Power reduction value (in dB, even numbers only)\n") +{ + int bts_nr = atoi(argv[0]); + int red = atoi(argv[1]); + struct gsm_bts *bts; + int rc; + + bts = gsm_bts_num(gsmnet_from_vty(vty), bts_nr); + if (!bts) { + vty_out(vty, "%% No such BTS (%d)%s", bts_nr, VTY_NEWLINE); + return CMD_WARNING; + } + + if (red % 2 != 0) { + vty_out(vty, "%% Incorrect BCCH power reduction value, " + "an even number is expected%s", VTY_NEWLINE); + return CMD_WARNING; + } + + rc = gsm_bts_set_c0_power_red(bts, red); + if (rc == -ENOTSUP) { + vty_out(vty, "%% BCCH carrier power reduction operation mode " + "is not supported for BTS%u%s", bts_nr, VTY_NEWLINE); + return CMD_WARNING; + } else if (rc != 0) { + vty_out(vty, "%% Failed to %sable BCCH carrier power reduction " + "operation mode for BTS%u%s", red ? "en" : "dis", + bts_nr, VTY_NEWLINE); + return CMD_WARNING; + } + + return CMD_SUCCESS; +} + /* this command is now hidden, as it's a low-level debug hack, and people should * instead use osmo-cbc these days */ DEFUN_HIDDEN(smscb_cmd, smscb_cmd_cmd, @@ -8172,6 +8213,7 @@ int bsc_vty_init(struct gsm_network *network) install_element(ENABLE_NODE, &restart_bts_cmd); install_element(ENABLE_NODE, &bts_resend_sysinfo_cmd); install_element(ENABLE_NODE, &bts_resend_power_ctrl_params_cmd); + install_element(ENABLE_NODE, &bts_c0_power_red_cmd); install_element(ENABLE_NODE, &pdch_act_cmd); install_element(ENABLE_NODE, &lchan_act_cmd); install_element(ENABLE_NODE, &lchan_act_all_cmd); 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", diff --git a/src/osmo-bsc/bts_osmobts.c b/src/osmo-bsc/bts_osmobts.c index 1814ada3d..9813a265d 100644 --- a/src/osmo-bsc/bts_osmobts.c +++ b/src/osmo-bsc/bts_osmobts.c @@ -1,6 +1,7 @@ /* Osmocom OsmoBTS specific code */ /* (C) 2010-2012 by Harald Welte <laforge@gnumonks.org> + * (C) 2021 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de> * * All Rights Reserved * @@ -43,6 +44,35 @@ extern struct gsm_bts_model bts_model_nanobts; static struct gsm_bts_model model_osmobts; +static int power_ctrl_set_c0_power_red(const struct gsm_bts *bts, + const uint8_t red) +{ + struct abis_rsl_dchan_hdr *dh; + struct msgb *msg; + + msg = rsl_msgb_alloc(); + if (msg == NULL) + return -ENOMEM; + + LOGP(DRSL, LOGL_NOTICE, "%sabling BCCH carrier power reduction " + "operation mode for BTS%u (maximum %u dB)\n", + red ? "En" : "Dis", bts->nr, red); + + /* Abuse the standard BS POWER CONTROL message by specifying 'Common Channel' + * in the Protocol Discriminator field and 'BCCH' in the Channel Number IE. */ + dh = (struct abis_rsl_dchan_hdr *) msgb_put(msg, sizeof(*dh)); + dh->c.msg_discr = ABIS_RSL_MDISC_COM_CHAN; + dh->c.msg_type = RSL_MT_BS_POWER_CONTROL; + dh->ie_chan = RSL_IE_CHAN_NR; + dh->chan_nr = RSL_CHAN_BCCH; + + msgb_tv_put(msg, RSL_IE_BS_POWER, red / 2); + + msg->dst = bts->c0->rsl_link_primary; + + return abis_rsl_sendmsg(msg); +} + int bts_model_osmobts_init(void) { model_osmobts = bts_model_nanobts; @@ -52,6 +82,9 @@ int bts_model_osmobts_init(void) /* Unlike nanoBTS, osmo-bts does support SI2bis and SI2ter fine */ model_osmobts.force_combined_si = false; + /* Power control API */ + model_osmobts.power_ctrl_set_c0_power_red = &power_ctrl_set_c0_power_red; + model_osmobts.features.data = &model_osmobts._features_data[0]; model_osmobts.features.data_len = sizeof(model_osmobts._features_data); diff --git a/tests/osmo-bsc.vty b/tests/osmo-bsc.vty index 48f3f0b6f..22e2a0668 100644 --- a/tests/osmo-bsc.vty +++ b/tests/osmo-bsc.vty @@ -46,10 +46,14 @@ OsmoBSC# bts ? OsmoBSC# bts 0 ? resend-system-information Re-generate + re-send BCCH SYSTEM INFORMATION resend-power-control-defaults Re-generate + re-send default MS/BS Power control parameters + c0-power-reduction BCCH carrier power reduction operation trx TRX for manual command oml Manipulate the OML managed objects om2000 Manipulate the OM2000 managed objects +OsmoBSC# bts 0 c0-power-reduction ? + <0-6> Power reduction value (in dB, even numbers only) + OsmoBSC# bts 0 trx ? <0-255> TRX Number |