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-rw-r--r--src/osmo-bts-trx/loops.c339
1 files changed, 339 insertions, 0 deletions
diff --git a/src/osmo-bts-trx/loops.c b/src/osmo-bts-trx/loops.c
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+++ b/src/osmo-bts-trx/loops.c
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+/* 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;
+
+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_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++;
+
+ 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_sacch_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(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;
+}
+
+int trx_loop_amr_input(struct trx_l1h *l1h, uint8_t chan_nr,
+ struct trx_chan_state *chan_state, float ber)
+{
+ struct gsm_lchan *lchan = &l1h->trx->ts[L1SAP_CHAN2TS(chan_nr)]
+ .lchan[l1sap_chan2ss(chan_nr)];
+ int c_i;
+
+ /* check if loop is enabled */
+ if (!chan_state->amr_loop)
+ return 0;
+
+ /* wait for MS to use the requested codec */
+ if (chan_state->ul_ft != chan_state->dl_cmr)
+ return 0;
+
+ /* count bit errors */
+ if (L1SAP_IS_CHAN_TCHH(chan_nr)) {
+ chan_state->ber_num += 2;
+ chan_state->ber_sum += (ber + ber);
+ } else {
+ chan_state->ber_num++;
+ chan_state->ber_sum += ber;
+ }
+
+ /* count frames */
+ if (chan_state->ber_num < 48)
+ return 0;
+
+ /* calculate average (reuse ber variable) */
+ ber = chan_state->ber_sum / chan_state->ber_num;
+
+ /* FIXME: calculate C/I from BER */
+ c_i = ber * 100;
+
+ /* reset bit errors */
+ chan_state->ber_num = 0;
+ chan_state->ber_sum = 0;
+
+ LOGP(DLOOP, LOGL_DEBUG, "Current bit error rate (BER) %.6f "
+ "codec id %d of trx=%u chan_nr=0x%02x\n", ber,
+ chan_state->ul_ft, l1h->trx->nr, chan_nr);
+
+ /* degrade */
+ if (chan_state->dl_cmr > 0) {
+ /* degrade, if ber is above threshold FIXME: C/I */
+ if (ber >
+ lchan->tch.amr_mr.mode[chan_state->dl_cmr-1].threshold_bts) {
+ LOGP(DLOOP, LOGL_DEBUG, "Degrading due to BER %.6f "
+ "from codec id %d to %d of trx=%u "
+ "chan_nr=0x%02x\n", ber, chan_state->dl_cmr,
+ chan_state->dl_cmr - 1, l1h->trx->nr, chan_nr);
+ chan_state->dl_cmr--;
+ }
+
+ return 0;
+ }
+
+ /* upgrade */
+ if (chan_state->dl_cmr < chan_state->codecs - 1) {
+ /* degrade, if ber is above threshold FIXME: C/I*/
+ if (ber <
+ lchan->tch.amr_mr.mode[chan_state->dl_cmr].threshold_bts
+ - lchan->tch.amr_mr.mode[chan_state->dl_cmr].hysteresis_bts) {
+ LOGP(DLOOP, LOGL_DEBUG, "Upgrading due to BER %.6f "
+ "from codec id %d to %d of trx=%u "
+ "chan_nr=0x%02x\n", ber, chan_state->dl_cmr,
+ chan_state->dl_cmr + 1, l1h->trx->nr, chan_nr);
+ chan_state->dl_cmr++;
+ }
+
+ return 0;
+ }
+
+ return 0;
+}
+
+int trx_loop_amr_set(struct trx_chan_state *chan_state, int loop)
+{
+ if (chan_state->amr_loop && !loop) {
+ chan_state->amr_loop = 0;
+
+ return 0;
+ }
+
+ if (!chan_state->amr_loop && loop) {
+ chan_state->amr_loop = 1;
+
+ /* reset bit errors */
+ chan_state->ber_num = 0;
+ chan_state->ber_sum = 0;
+
+ return 0;
+ }
+
+ return 0;
+}
+