diff options
author | Andreas Eversberg <jolly@eversberg.eu> | 2013-02-24 11:09:19 +0100 |
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committer | Harald Welte <laforge@gnumonks.org> | 2015-09-22 16:41:27 +0200 |
commit | 219ece83a3ffe7fa2bd58943cddb47a3eacc2fab (patch) | |
tree | 0a15b4b0e68a2f7b4a199d7d811b56be12e8069a /src/osmo-bts-trx/loops.c | |
parent | 889890da4312916bd617b3c95326a89237078a3b (diff) |
TRX: Implementation of MS power and timing advance loops
Diffstat (limited to 'src/osmo-bts-trx/loops.c')
-rw-r--r-- | src/osmo-bts-trx/loops.c | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/src/osmo-bts-trx/loops.c b/src/osmo-bts-trx/loops.c new file mode 100644 index 00000000..c8815286 --- /dev/null +++ b/src/osmo-bts-trx/loops.c @@ -0,0 +1,251 @@ +/* Loop control for OsmoBTS-TRX */ + +/* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu> + * + * 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 <stdlib.h> +#include <errno.h> + +#include <osmo-bts/gsm_data.h> +#include <osmo-bts/logging.h> +#include <osmo-bts/l1sap.h> +#include <osmocom/core/bits.h> + +#include "trx_if.h" +#include "l1_if.h" +#include "loops.h" + +#define MS_PWR_DBM(lvl) ms_pwr_dbm(gsm_arfcn2band(l1h->config.arfcn), lvl) + +/* + * MS Power loop + */ + +int trx_ms_power_loop = 0; +int8_t trx_target_rssi = -10; + +/* how much power levels do we raise/lower as maximum (1 level = 2 dB) */ +#define MS_RAISE_MAX 4 +#define MS_LOWER_MAX 4 + +static int ms_power_diff(struct trx_l1h *l1h, struct gsm_lchan *lchan, + uint8_t chan_nr, struct trx_chan_state *chan_state, int8_t diff) +{ + int8_t new_power; + + new_power = lchan->ms_power - (diff >> 1); + + if (diff == 0) + return 0; + + if (new_power < 0) + new_power = 0; + + // FIXME: to go above 1W, we need to know classmark of MS + if (l1h->config.arfcn >= 512 && l1h->config.arfcn <= 885) { + if (new_power > 15) + new_power = 15; + } else { + if (new_power > 19) + new_power = 19; + } + + /* a higher value means a lower level (and vice versa) */ + if (new_power > lchan->ms_power + MS_LOWER_MAX) + new_power = lchan->ms_power + MS_LOWER_MAX; + else if (new_power < lchan->ms_power - MS_RAISE_MAX) + new_power = lchan->ms_power - MS_RAISE_MAX; + + if (lchan->ms_power == new_power) { + LOGP(DLOOP, LOGL_INFO, "Keeping MS new_power of trx=%u " + "chan_nr=0x%02x at control level %d (%d dBm)\n", + l1h->trx->nr, chan_nr, new_power, + MS_PWR_DBM(new_power)); + + return 0; + } + + LOGP(DLOOP, LOGL_INFO, "%s MS new_power of trx=%u chan_nr=0x%02x from " + "control level %d (%d dBm) to %d (%d dBm)\n", + (diff > 0) ? "Raising" : "Lowering", + l1h->trx->nr, chan_nr, lchan->ms_power, + MS_PWR_DBM(lchan->ms_power), new_power, MS_PWR_DBM(new_power)); + + lchan->ms_power = new_power; + + return 0; +} + +static int ms_power_val(struct trx_l1h *l1h, struct gsm_lchan *lchan, + uint8_t chan_nr, struct trx_chan_state *chan_state, int8_t rssi) +{ + /* ignore inserted dummy frames, treat as lost frames */ + if (rssi < -127) + return 0; + + LOGP(DLOOP, LOGL_DEBUG, "Got RSSI value of %d\n", rssi); + + chan_state->meas.rssi_count++; + + /* check if the current L1 header compares to the current ordered TA */ +// if ((lchan->meas.l1_info[0] >> 3) != lchan->ms_power) +// return 0; + + chan_state->meas.rssi_got_burst = 1; + + /* store and process RSSI */ + if (chan_state->meas.rssi_valid_count + == ARRAY_SIZE(chan_state->meas.rssi)) + return 0; + chan_state->meas.rssi[chan_state->meas.rssi_valid_count++] = rssi; + chan_state->meas.rssi_valid_count++; + + return 0; +} + +static int ms_power_clock(struct trx_l1h *l1h, struct gsm_lchan *lchan, + uint8_t chan_nr, struct trx_chan_state *chan_state) +{ + int rssi; + int i; + + /* skip every second clock, to prevent oscillating due to roundtrip + * delay */ + if (!(chan_state->meas.clock & 1)) + return 0; + + LOGP(DLOOP, LOGL_DEBUG, "Got SACCH master clock at RSSI count %d\n", + chan_state->meas.rssi_count); + + /* wait for initial burst */ + if (!chan_state->meas.rssi_got_burst) + return 0; + + /* if no burst was received from MS at clock */ + if (chan_state->meas.rssi_count == 0) { + LOGP(DLOOP, LOGL_NOTICE, "LOST SACCH frame of trx=%u " + "chan_nr=0x%02x, so we raise MS power\n", + l1h->trx->nr, chan_nr); + return ms_power_diff(l1h, lchan, chan_nr, chan_state, + MS_RAISE_MAX); + } + + /* reset total counter */ + chan_state->meas.rssi_count = 0; + + /* check the minimum level received after MS acknowledged the ordered + * power level */ + if (chan_state->meas.rssi_valid_count == 0) + return 0; + for (rssi = 999, i = 0; i < chan_state->meas.rssi_valid_count; i++) { + if (rssi > chan_state->meas.rssi[i]) + rssi = chan_state->meas.rssi[i]; + } + + /* reset valid counter */ + chan_state->meas.rssi_valid_count = 0; + + /* change RSSI */ + LOGP(DLOOP, LOGL_DEBUG, "Lowest RSSI: %d Target RSSI: %d Current " + "MS power: %d (%d dBm) of trx=%u chan_nr=0x%02x\n", rssi, + trx_target_rssi, lchan->ms_power, MS_PWR_DBM(lchan->ms_power), + l1h->trx->nr, chan_nr); + ms_power_diff(l1h, lchan, chan_nr, chan_state, trx_target_rssi - rssi); + + return 0; +} + + +/* + * Timing Advance loop + */ + +int trx_ta_loop = 1; + +int ta_val(struct trx_l1h *l1h, struct gsm_lchan *lchan, uint8_t chan_nr, + struct trx_chan_state *chan_state, float toa) +{ + /* check if the current L1 header acks to the current ordered TA */ + if (lchan->meas.l1_info[1] != lchan->rqd_ta) + return 0; + + /* sum measurement */ + chan_state->meas.toa_sum += toa; + if (++(chan_state->meas.toa_num) < 16) + return 0; + + /* complete set */ + toa = chan_state->meas.toa_sum / chan_state->meas.toa_num; + + /* check for change of TOA */ + if (toa < -0.9F && lchan->rqd_ta > 0) { + LOGP(DLOOP, LOGL_INFO, "TOA of trx=%u chan_nr=0x%02x is too " + "early (%.2f), now lowering TA from %d to %d\n", + l1h->trx->nr, chan_nr, toa, lchan->rqd_ta, + lchan->rqd_ta - 1); + lchan->rqd_ta--; + } else if (toa > 0.9F && lchan->rqd_ta < 63) { + LOGP(DLOOP, LOGL_INFO, "TOA of trx=%u chan_nr=0x%02x is too " + "late (%.2f), now raising TA from %d to %d\n", + l1h->trx->nr, chan_nr, toa, lchan->rqd_ta, + lchan->rqd_ta + 1); + lchan->rqd_ta++; + } else + LOGP(DLOOP, LOGL_INFO, "TOA of trx=%u chan_nr=0x%02x is " + "correct (%.2f), keeping current TA of %d\n", + l1h->trx->nr, chan_nr, toa, lchan->rqd_ta); + + chan_state->meas.toa_num = 0; + chan_state->meas.toa_sum = 0; + + return 0; +} + +int trx_loop_input(struct trx_l1h *l1h, uint8_t chan_nr, + struct trx_chan_state *chan_state, int8_t rssi, float toa) +{ + struct gsm_lchan *lchan = &l1h->trx->ts[L1SAP_CHAN2TS(chan_nr)] + .lchan[l1sap_chan2ss(chan_nr)]; + + if (trx_ms_power_loop) + ms_power_val(l1h, lchan, chan_nr, chan_state, rssi); + + if (trx_ta_loop) + ta_val(l1h, lchan, chan_nr, chan_state, toa); + + return 0; +} + +int trx_loop_sacch_clock(struct trx_l1h *l1h, uint8_t chan_nr, + struct trx_chan_state *chan_state) +{ + struct gsm_lchan *lchan = &l1h->trx->ts[L1SAP_CHAN2TS(chan_nr)] + .lchan[l1sap_chan2ss(chan_nr)]; + + if (trx_ms_power_loop) + ms_power_clock(l1h, lchan, chan_nr, chan_state); + + /* count the number of SACCH clocks */ + chan_state->meas.clock++; + + return 0; +} + |