diff options
Diffstat (limited to 'src/osmo-bts-trx/amr_loop.c')
| -rw-r--r-- | src/osmo-bts-trx/amr_loop.c | 81 |
1 files changed, 42 insertions, 39 deletions
diff --git a/src/osmo-bts-trx/amr_loop.c b/src/osmo-bts-trx/amr_loop.c index e5c7fec4..5793d03f 100644 --- a/src/osmo-bts-trx/amr_loop.c +++ b/src/osmo-bts-trx/amr_loop.c @@ -1,6 +1,7 @@ /* AMR link adaptation loop (see 3GPP TS 45.009, section 3) */ /* (C) 2013 by Andreas Eversberg <jolly@eversberg.eu> + * (C) 2022 by sysmocom - s.m.f.c. GmbH <info@sysmocom.de> * * All Rights Reserved * @@ -32,16 +33,11 @@ #include "amr_loop.h" void trx_loop_amr_input(struct l1sched_chan_state *chan_state, - int n_errors, int n_bits_total) + const struct l1sched_meas_set *meas_set) { - struct gsm_lchan *lchan = chan_state->lchan; - float ber; - - /* calculate BER (Bit Error Ratio) */ - if (n_bits_total == 0) - ber = 1.0; /* 100% BER */ - else - ber = (float) n_errors / (float) n_bits_total; + const struct gsm_lchan *lchan = chan_state->lchan; + const struct amr_multirate_conf *cfg = &lchan->tch.amr_mr; + int lqual_cb = meas_set->ci_cb; /* cB (centibel) */ /* check if loop is enabled */ if (!chan_state->amr_loop) @@ -51,47 +47,54 @@ void trx_loop_amr_input(struct l1sched_chan_state *chan_state, if (chan_state->ul_ft != chan_state->dl_cmr) return; - /* count bit errors */ + /* count per-block C/I samples for further averaging */ if (lchan->type == GSM_LCHAN_TCH_H) { - chan_state->ber_num += 2; - chan_state->ber_sum += (ber + ber); + chan_state->lqual_cb_num += 2; + chan_state->lqual_cb_sum += (lqual_cb + lqual_cb); } else { - chan_state->ber_num++; - chan_state->ber_sum += ber; + chan_state->lqual_cb_num++; + chan_state->lqual_cb_sum += lqual_cb; } /* count frames */ - if (chan_state->ber_num < 48) + if (chan_state->lqual_cb_num < 48) return; - /* calculate average (reuse ber variable) */ - ber = chan_state->ber_sum / chan_state->ber_num; + /* calculate average (reuse lqual_cb variable) */ + lqual_cb = chan_state->lqual_cb_sum / chan_state->lqual_cb_num; - /* reset bit errors */ - chan_state->ber_num = 0; - chan_state->ber_sum = 0; + LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "AMR link quality (C/I) is %d cB, " + "codec mode=%d\n", lqual_cb, chan_state->ul_ft); - LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Current bit error rate (BER) %.6f " - "codec id %d\n", ber, chan_state->ul_ft); + /* reset the link quality measurements */ + chan_state->lqual_cb_num = 0; + chan_state->lqual_cb_sum = 0; - /* 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) { - LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Degrading due to BER %.6f " - "from codec id %d to %d\n", ber, chan_state->dl_cmr, - chan_state->dl_cmr - 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_lower_cb = cfg->mode[chan_state->dl_cmr - 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: " + "%d -> %d due to link quality %d cB < THR_MX_Dn=%d cB\n", + chan_state->dl_cmr, chan_state->dl_cmr - 1, + lqual_cb, thresh_lower_cb); chan_state->dl_cmr--; } } else 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 - - lchan->tch.amr_mr.mode[chan_state->dl_cmr].hysteresis) { - LOGPLCHAN(lchan, DLOOP, LOGL_DEBUG, "Upgrading due to BER %.6f " - "from codec id %d to %d\n", ber, chan_state->dl_cmr, - chan_state->dl_cmr + 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[chan_state->dl_cmr].threshold * 5 \ + + cfg->mode[chan_state->dl_cmr].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: " + "%d -> %d due to link quality %d cB > THR_MX_Up=%d cB\n", + chan_state->dl_cmr, chan_state->dl_cmr + 1, + lqual_cb, thresh_upper_cb); chan_state->dl_cmr++; } } @@ -102,9 +105,9 @@ void trx_loop_amr_set(struct l1sched_chan_state *chan_state, int loop) if (chan_state->amr_loop == loop) return; if (!chan_state->amr_loop) { - /* reset bit errors */ - chan_state->ber_num = 0; - chan_state->ber_sum = 0; + /* reset the link quality measurements */ + chan_state->lqual_cb_num = 0; + chan_state->lqual_cb_sum = 0; } chan_state->amr_loop = loop; |