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osmo-bts-trx: use C/I in the AMR link adaptation loop 

Change-Id: Ide84bf864f56020c0265cfb9731615d4f7bad7f5
Related: SYS#5917, OS#4984
This commit is contained in:
Vadim Yanitskiy 2022-04-12 16:12:41 +03:00 committed by fixeria
parent cfabf6275e
commit 44cb0113cf
6 changed files with 53 additions and 49 deletions
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4
include/osmo-bts/scheduler.h
View File

@ -114,8 +114,8 @@ struct l1sched_chan_state {
/* AMR */
uint8_t codec[4]; /* 4 possible codecs for amr */
int codecs; /* number of possible codecs */
float ber_sum; /* sum of bit error rates */
int ber_num; /* number of bit error rates */
int lqual_cb_sum; /* sum of link quality samples (in cB) */
int lqual_cb_num; /* number of link quality samples */
uint8_t ul_ft; /* current uplink FT index */
uint8_t dl_ft; /* current downlink FT index */
uint8_t ul_cmr; /* current uplink CMR index */

4
src/common/scheduler.c
View File

@ -1185,8 +1185,8 @@ int trx_sched_set_mode(struct gsm_bts_trx_ts *ts, uint8_t chan_nr, uint8_t rsl_c
chan_state->dl_ft = initial_id;
chan_state->ul_cmr = initial_id;
chan_state->dl_cmr = initial_id;
chan_state->ber_sum = 0;
chan_state->ber_num = 0;
chan_state->lqual_cb_sum = 0;
chan_state->lqual_cb_num = 0;
}
rc = 0;
}

81
src/osmo-bts-trx/amr_loop.c
View File

@ -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;

2
src/osmo-bts-trx/amr_loop.h
View File

@ -11,6 +11,6 @@
*/
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);
void trx_loop_amr_set(struct l1sched_chan_state *chan_state, int loop);

5
src/osmo-bts-trx/sched_lchan_tchf.c
View File

@ -197,8 +197,6 @@ int rx_tchf_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
break;
}
if (rc)
trx_loop_amr_input(chan_state, n_errors, n_bits_total);
/* only good speech frames get rtp header */
if (rc != GSM_MACBLOCK_LEN && rc >= 4) {
if (chan_state->amr_last_dtx == AMR_OTHER) {
@ -225,6 +223,9 @@ int rx_tchf_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
/* meas_avg.fn now contains TDMA frame number of the first burst */
fn_begin = meas_avg.fn;
if (tch_mode == GSM48_CMODE_SPEECH_AMR)
trx_loop_amr_input(chan_state, &meas_avg);
/* Check if the frame is bad */
if (rc < 0) {
LOGL1SB(DL1P, LOGL_NOTICE, l1ts, bi, "Received bad data (%u/%u)\n",

6
src/osmo-bts-trx/sched_lchan_tchh.c
View File

@ -233,9 +233,6 @@ int rx_tchh_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
break;
}
if (rc)
trx_loop_amr_input(chan_state, n_errors, n_bits_total);
/* only good speech frames get rtp header */
if (rc != GSM_MACBLOCK_LEN && rc >= 4) {
if (chan_state->amr_last_dtx == AMR_OTHER) {
@ -264,6 +261,9 @@ int rx_tchh_fn(struct l1sched_ts *l1ts, const struct trx_ul_burst_ind *bi)
/* meas_avg.fn now contains TDMA frame number of the first burst */
fn_begin = meas_avg.fn;
if (tch_mode == GSM48_CMODE_SPEECH_AMR)
trx_loop_amr_input(chan_state, &meas_avg);
/* Check if the frame is bad */
if (rc < 0) {
LOGL1SB(DL1P, LOGL_NOTICE, l1ts, bi, "Received bad data (%u/%u)\n",