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/* MS Power Control Loop L1 */
/* (C) 2014 by Holger Hans Peter Freyther
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <inttypes.h>
#include <osmo-bts/logging.h>
#include <osmo-bts/bts.h>
#include <osmo-bts/gsm_data.h>
#include <osmo-bts/measurement.h>
#include <osmo-bts/bts_model.h>
#include <osmo-bts/l1sap.h>
#include <osmo-bts/power_control.h>
/* how many dB do we raise/lower as maximum (1 ms power level = 2 dB) */
#define MS_RAISE_MAX_DB 4
#define MS_LOWER_MAX_DB 8
/*! compute the new MS POWER LEVEL communicated to the MS and store it in lchan.
* \param lchan logical channel for which to compute (and in which to store) new power value.
* \param[in] ms_power_lvl MS Power Level received from Uplink L1 SACCH Header in SACCH block.
* \param[in] rxLevel Signal level of the received SACCH block, in dBm.
*/
int lchan_ms_pwr_ctrl(struct gsm_lchan *lchan,
const uint8_t ms_power_lvl, const int rxLevel)
{
int diff;
struct gsm_bts_trx *trx = lchan->ts->trx;
struct gsm_bts *bts = trx->bts;
enum gsm_band band = bts->band;
int8_t new_power_lvl; /* TS 05.05 power level */
int8_t ms_dbm, new_dbm, current_dbm, bsc_max_dbm;
if (!trx_ms_pwr_ctrl_is_osmo(lchan->ts->trx))
return 0;
if (lchan->ms_power_ctrl.fixed)
return 0;
ms_dbm = ms_pwr_dbm(band, ms_power_lvl);
if (ms_dbm < 0) {
LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,
"Failed to calculate dBm for power ctl level %" PRIu8 " on band %s\n",
ms_power_lvl, gsm_band_name(band));
return 0;
}
bsc_max_dbm = ms_pwr_dbm(band, lchan->ms_power_ctrl.max);
if (bsc_max_dbm < 0) {
LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,
"Failed to calculate dBm for power ctl level %" PRIu8 " on band %s\n",
lchan->ms_power_ctrl.max, gsm_band_name(band));
return 0;
}
/* How many dBs measured power should be increased (+) or decreased (-)
to reach expected power. */
diff = bts->ul_power_target - rxLevel;
/* don't ever change more than MS_{LOWER,RAISE}_MAX_DBM during one loop
iteration, i.e. reduce the speed at which the MS transmit power can
change. A higher value means a lower level (and vice versa) */
if (diff > MS_RAISE_MAX_DB)
diff = MS_RAISE_MAX_DB;
else if (diff < -MS_LOWER_MAX_DB)
diff = -MS_LOWER_MAX_DB;
new_dbm = ms_dbm + diff;
/* Make sure new_dbm is never negative. ms_pwr_ctl_lvl() can later on
cope with any unsigned dbm value, regardless of band minimal value. */
if (new_dbm < 0)
new_dbm = 0;
/* Don't ask for smaller ms power level than the one set by BSC upon RSL CHAN ACT */
if (new_dbm > bsc_max_dbm)
new_dbm = bsc_max_dbm;
new_power_lvl = ms_pwr_ctl_lvl(band, new_dbm);
if (new_power_lvl < 0) {
LOGPLCHAN(lchan, DLOOP, LOGL_NOTICE,
"Failed to retrieve power level for %" PRId8 " dBm on band %d\n",
new_dbm, band);
return 0;
}
if (lchan->ms_power_ctrl.current == new_power_lvl) {
LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Keeping MS power at control level %d, %d dBm "
"(rx-ms-pwr-lvl %" PRIu8 ", max-ms-pwr-lvl %" PRIu8 ", rx-current %d dBm, rx-target %d dBm)\n",
new_power_lvl, new_dbm,
ms_power_lvl, lchan->ms_power_ctrl.max,
rxLevel, bts->ul_power_target);
return 0;
}
current_dbm = ms_pwr_dbm(band, lchan->ms_power_ctrl.current);
LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "%s MS power from control level %d (%d dBm) to %d, %d dBm "
"(rx-ms-pwr-lvl %" PRIu8 ", max-ms-pwr-lvl %" PRIu8 ", rx-current %d dBm, rx-target %d dBm)\n",
(new_dbm > current_dbm) ? "Raising" : "Lowering",
lchan->ms_power_ctrl.current, current_dbm, new_power_lvl, new_dbm,
ms_power_lvl, lchan->ms_power_ctrl.max,
rxLevel, bts->ul_power_target);
/* store the resulting new MS power level in the lchan */
lchan->ms_power_ctrl.current = new_power_lvl;
bts_model_adjst_ms_pwr(lchan);
return 1;
}
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