108 lines
3.6 KiB
C
108 lines
3.6 KiB
C
/* AMR link adaptation loop (see 3GPP TS 45.009, section 3) */
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/* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu>
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* (C) 2022 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de>
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*
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* All Rights Reserved
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#include <stdint.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <inttypes.h>
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#include <osmo-bts/gsm_data.h>
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#include <osmo-bts/logging.h>
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#include <osmocom/gsm/gsm_utils.h>
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#include "amr_loop.h"
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void trx_loop_amr_input(struct l1sched_chan_state *chan_state,
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const struct l1sched_meas_set *meas_set)
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{
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const struct gsm_lchan *lchan = chan_state->lchan;
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const struct amr_multirate_conf *cfg = &lchan->tch.amr_mr;
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const uint8_t mi = chan_state->ul_ft; /* mode index 0..3 */
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int lqual_cb = meas_set->ci_cb; /* cB (centibel) */
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/* count per-block C/I samples for further averaging */
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if (lchan->type == GSM_LCHAN_TCH_H) {
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chan_state->lqual_cb_num += 2;
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chan_state->lqual_cb_sum += (lqual_cb + lqual_cb);
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} else {
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chan_state->lqual_cb_num++;
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chan_state->lqual_cb_sum += lqual_cb;
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}
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/* wait for MS to use the requested codec */
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if (mi != chan_state->dl_cmr)
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return;
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/* count frames */
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if (chan_state->lqual_cb_num < 48)
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return;
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/* calculate average (reuse lqual_cb variable) */
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lqual_cb = chan_state->lqual_cb_sum / chan_state->lqual_cb_num;
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LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "AMR link quality (C/I) is %d cB, "
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"codec mode[%u]=%u\n", lqual_cb, mi, cfg->mode[mi].mode);
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/* reset the link quality measurements */
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chan_state->lqual_cb_num = 0;
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chan_state->lqual_cb_sum = 0;
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/* If the current codec mode can be degraded */
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if (mi > 0) {
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/* The threshold/hysteresis is in 0.5 dB steps, convert to cB:
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* 1dB is 10cB, so 0.5dB is 5cB - this is why we multiply by 5. */
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const int thresh_lower_cb = cfg->mode[mi - 1].threshold * 5;
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/* Degrade if the link quality is below THR_MX_Dn(i - 1) */
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if (lqual_cb < thresh_lower_cb) {
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LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Degrading AMR codec mode: "
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"[%u]=%u -> [%u]=%u due to link quality %d cB < THR_MX_Dn=%d cB\n",
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mi, cfg->mode[mi].mode, mi - 1, cfg->mode[mi - 1].mode,
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lqual_cb, thresh_lower_cb);
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chan_state->dl_cmr--;
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return;
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}
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}
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/* If the current codec mode can be upgraded */
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if (mi < chan_state->codecs - 1) {
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/* The threshold/hysteresis is in 0.5 dB steps, convert to cB:
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* 1dB is 10cB, so 0.5dB is 5cB - this is why we multiply by 5. */
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const int thresh_upper_cb = cfg->mode[mi].threshold * 5 \
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+ cfg->mode[mi].hysteresis * 5;
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/* Upgrade if the link quality is above THR_MX_Up(i) */
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if (lqual_cb > thresh_upper_cb) {
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LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Upgrading AMR codec mode: "
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"[%u]=%u -> [%u]=%u due to link quality %d cB > THR_MX_Up=%d cB\n",
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mi, cfg->mode[mi].mode, mi + 1, cfg->mode[mi + 1].mode,
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lqual_cb, thresh_upper_cb);
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chan_state->dl_cmr++;
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return;
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}
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}
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LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Keeping the current AMR codec "
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"mode[%u]=%u\n", mi, cfg->mode[mi].mode);
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}
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