diff options
Diffstat (limited to 'src/osmo-bts-trx/amr_loop.c')
| -rw-r--r-- | src/osmo-bts-trx/amr_loop.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/src/osmo-bts-trx/amr_loop.c b/src/osmo-bts-trx/amr_loop.c new file mode 100644 index 00000000..cf75a8fc --- /dev/null +++ b/src/osmo-bts-trx/amr_loop.c @@ -0,0 +1,107 @@ +/* AMR link adaptation loop (see 3GPP TS 45.009, section 3) */ + +/* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu> + * (C) 2022 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de> + * + * 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 Affero 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 <inttypes.h> + +#include <osmo-bts/gsm_data.h> +#include <osmo-bts/logging.h> +#include <osmocom/gsm/gsm_utils.h> + +#include "amr_loop.h" + +void trx_loop_amr_input(struct l1sched_chan_state *chan_state, + const struct l1sched_meas_set *meas_set) +{ + const struct gsm_lchan *lchan = chan_state->lchan; + const struct amr_multirate_conf *cfg = &lchan->tch.amr_mr; + const uint8_t mi = chan_state->ul_ft; /* mode index 0..3 */ + int lqual_cb = meas_set->ci_cb; /* cB (centibel) */ + + /* count per-block C/I samples for further averaging */ + if (lchan->type == GSM_LCHAN_TCH_H) { + chan_state->lqual_cb_num += 2; + chan_state->lqual_cb_sum += (lqual_cb + lqual_cb); + } else { + chan_state->lqual_cb_num++; + chan_state->lqual_cb_sum += lqual_cb; + } + + /* wait for MS to use the requested codec */ + if (mi != chan_state->dl_cmr) + return; + + /* count frames */ + if (chan_state->lqual_cb_num < 48) + return; + + /* calculate average (reuse lqual_cb variable) */ + lqual_cb = chan_state->lqual_cb_sum / chan_state->lqual_cb_num; + + LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "AMR link quality (C/I) is %d cB, " + "codec mode[%u]=%u\n", lqual_cb, mi, cfg->mode[mi].mode); + + /* reset the link quality measurements */ + chan_state->lqual_cb_num = 0; + chan_state->lqual_cb_sum = 0; + + /* If the current codec mode can be degraded */ + if (mi > 0) { + /* The threshold/hysteresis is in 0.5 dB steps, convert to cB: + * 1dB is 10cB, so 0.5dB is 5cB - this is why we multiply by 5. */ + const int thresh_lower_cb = cfg->mode[mi - 1].threshold * 5; + + /* Degrade if the link quality is below THR_MX_Dn(i - 1) */ + if (lqual_cb < thresh_lower_cb) { + LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Degrading AMR codec mode: " + "[%u]=%u -> [%u]=%u due to link quality %d cB < THR_MX_Dn=%d cB\n", + mi, cfg->mode[mi].mode, mi - 1, cfg->mode[mi - 1].mode, + lqual_cb, thresh_lower_cb); + chan_state->dl_cmr--; + return; + } + } + + /* If the current codec mode can be upgraded */ + if (mi < chan_state->codecs - 1) { + /* The threshold/hysteresis is in 0.5 dB steps, convert to cB: + * 1dB is 10cB, so 0.5dB is 5cB - this is why we multiply by 5. */ + const int thresh_upper_cb = cfg->mode[mi].threshold * 5 \ + + cfg->mode[mi].hysteresis * 5; + + /* Upgrade if the link quality is above THR_MX_Up(i) */ + if (lqual_cb > thresh_upper_cb) { + LOGPLCHAN(lchan, DLOOP, LOGL_INFO, "Upgrading AMR codec mode: " + "[%u]=%u -> [%u]=%u due to link quality %d cB > THR_MX_Up=%d cB\n", + mi, cfg->mode[mi].mode, mi + 1, cfg->mode[mi + 1].mode, + lqual_cb, thresh_upper_cb); + chan_state->dl_cmr++; + return; + } + } + + LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Keeping the current AMR codec " + "mode[%u]=%u\n", mi, cfg->mode[mi].mode); +} |