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Clarify and refactor link quality (C/I) handling 

The radio link quality is defined by C/I (Carrier-to-Interference
ratio), which is computed from the training sequence of each
received burst, by comparing the "ideal" training sequence with
the actual (received) one.

Link quality measurements are used by L1SAP to filter out "ghost"
Access Bursts, and by the link quality adaptation algorithms. One
can define minimum link quality values using the VTY interface.

On the VTY interface we expect integer C/I values in centiBels
(cB, 10e-2 B), while the internal structures are using float
values in deciBels (dB, 10e-1 B). Some PHYs (sysmo, octphy,
oc2g, and litecell15) expose C/I measurements in deciBels,
while on the L1SAP interface we finally send then in centiBels.

Let's avoid this confusion and stick to a single format, that
will be used by the internal logic of OsmoBTS - integer values
(int16_t) in centiBels. This will give us the range of:

  -32768  .. 32767  centiBels, or
  -3276.8 .. 3276.7 deciBels,

which is certainly sufficient.

Change-Id: If624d6fdc0270e6813af8700d95f1345903c8a01
This commit is contained in:
Vadim Yanitskiy 2019-07-07 19:58:48 +07:00 committed by laforge
parent db6c786350
commit 9649a42d5a
9 changed files with 22 additions and 22 deletions
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8
doc/manuals/vty/bts_vty_reference.xml
View File

@ -1613,14 +1613,14 @@
</command>
<command id='min-qual-rach &lt;-100-100&gt;'>
<params>
<param name='min-qual-rach' doc='Set the minimum quality level of RACH burst to be accpeted' />
<param name='&lt;-100-100&gt;' doc='C/I level in tenth of dB' />
<param name='min-qual-rach' doc='Set the minimum link quality level of Access Bursts to be accepted' />
<param name='&lt;-100-100&gt;' doc='C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)' />
</params>
</command>
<command id='min-qual-norm &lt;-100-100&gt;'>
<params>
<param name='min-qual-norm' doc='Set the minimum quality level of normal burst to be accpeted' />
<param name='&lt;-100-100&gt;' doc='C/I level in tenth of dB' />
<param name='min-qual-norm' doc='Set the minimum link quality level of Normal Bursts to be accepted' />
<param name='&lt;-100-100&gt;' doc='C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)' />
</params>
</command>
<command id='nominal-tx-power &lt;0-100&gt;'>

4
include/osmo-bts/gsm_data_shared.h
View File

@ -759,8 +759,8 @@ struct gsm_bts {
int smscb_queue_max_len; /* maximum queue length */
int smscb_queue_hyst; /* hysteresis for CBCH laod indications */
float min_qual_rach; /* minimum quality for RACH bursts */
float min_qual_norm; /* minimum quality for normal daata */
int16_t min_qual_rach; /* minimum link quality (in centiBels) for Access Bursts */
int16_t min_qual_norm; /* minimum link quality (in centiBels) for Normal Bursts */
uint16_t max_ber10k_rach; /* Maximum permitted RACH BER in 0.01% */
struct {

4
src/common/bts.c
View File

@ -51,8 +51,8 @@
#include <osmo-bts/dtx_dl_amr_fsm.h>
#include <osmo-bts/cbch.h>
#define MIN_QUAL_RACH 5.0f /* at least 5 dB C/I */
#define MIN_QUAL_NORM -0.5f /* at least -1 dB C/I */
#define MIN_QUAL_RACH 50 /* minimum link quality (in centiBels) for Access Bursts */
#define MIN_QUAL_NORM -5 /* minimum link quality (in centiBels) for Normal Bursts */
static void bts_update_agch_max_queue_length(struct gsm_bts *bts);

2
src/common/l1sap.c
View File

@ -1218,7 +1218,7 @@ static int l1sap_tch_ind(struct gsm_bts_trx *trx, struct osmo_phsap_prim *l1sap,
* the content is not available due to decoding issues. Content not
* available is expected as empty payload. We also check if quality is
* good enough. */
if (msg->len && tch_ind->lqual_cb / 10 >= bts->min_qual_norm) {
if (msg->len && tch_ind->lqual_cb >= bts->min_qual_norm) {
/* hand msg to RTP code for transmission */
if (lchan->abis_ip.rtp_socket)
osmo_rtp_send_frame_ext(lchan->abis_ip.rtp_socket,

4
src/common/pcu_sock.c
View File

@ -330,8 +330,8 @@ int pcu_tx_data_ind(struct gsm_bts_trx_ts *ts, uint8_t sapi, uint32_t fn,
LOGP(DPCU, LOGL_DEBUG, "Sending data indication: sapi=%s arfcn=%d block=%d data=%s\n",
sapi_string[sapi], arfcn, block_nr, osmo_hexdump(data, len));
if (lqual / 10 < bts->min_qual_norm) {
LOGP(DPCU, LOGL_DEBUG, "Link quality %"PRId16" is below threshold %f, dropping packet\n",
if (lqual < bts->min_qual_norm) {
LOGP(DPCU, LOGL_DEBUG, "Link quality %"PRId16" is below threshold %d, dropping packet\n",
lqual, bts->min_qual_norm);
return 0;
}

16
src/common/vty.c
View File

@ -300,9 +300,9 @@ static void config_write_bts_single(struct vty *vty, struct gsm_bts *bts)
sapi_buf = osmo_str_tolower(get_value_string(gsmtap_sapi_names, GSMTAP_CHANNEL_ACCH));
vty_out(vty, " gsmtap-sapi %s%s", sapi_buf, VTY_NEWLINE);
}
vty_out(vty, " min-qual-rach %.0f%s", bts->min_qual_rach * 10.0f,
vty_out(vty, " min-qual-rach %d%s", bts->min_qual_rach,
VTY_NEWLINE);
vty_out(vty, " min-qual-norm %.0f%s", bts->min_qual_norm * 10.0f,
vty_out(vty, " min-qual-norm %d%s", bts->min_qual_norm,
VTY_NEWLINE);
vty_out(vty, " max-ber10k-rach %u%s", bts->max_ber10k_rach,
VTY_NEWLINE);
@ -618,24 +618,24 @@ DEFUN(cfg_bts_ul_power_target, cfg_bts_ul_power_target_cmd,
DEFUN(cfg_bts_min_qual_rach, cfg_bts_min_qual_rach_cmd,
"min-qual-rach <-100-100>",
"Set the minimum quality level of RACH burst to be accpeted\n"
"C/I level in tenth of dB\n")
"Set the minimum link quality level of Access Bursts to be accepted\n"
"C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)\n")
{
struct gsm_bts *bts = vty->index;
bts->min_qual_rach = strtof(argv[0], NULL) / 10.0f;
bts->min_qual_rach = atoi(argv[0]);
return CMD_SUCCESS;
}
DEFUN(cfg_bts_min_qual_norm, cfg_bts_min_qual_norm_cmd,
"min-qual-norm <-100-100>",
"Set the minimum quality level of normal burst to be accpeted\n"
"C/I level in tenth of dB\n")
"Set the minimum link quality level of Normal Bursts to be accepted\n"
"C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)\n")
{
struct gsm_bts *bts = vty->index;
bts->min_qual_norm = strtof(argv[0], NULL) / 10.0f;
bts->min_qual_norm = atoi(argv[0]);
return CMD_SUCCESS;
}

2
src/osmo-bts-litecell15/l1_if.c
View File

@ -1004,7 +1004,7 @@ static int handle_ph_ra_ind(struct lc15l1_hdl *fl1, GsmL1_PhRaInd_t *ra_ind,
struct ph_rach_ind_param rach_ind_param;
/* FIXME: this should be deprecated/obsoleted as it bypasses rach.busy counting */
if (ra_ind->measParam.fLinkQuality < bts->min_qual_rach) {
if (ra_ind->measParam.fLinkQuality * 10 < bts->min_qual_rach) {
msgb_free(l1p_msg);
return 0;
}

2
src/osmo-bts-oc2g/l1_if.c
View File

@ -1060,7 +1060,7 @@ static int handle_ph_ra_ind(struct oc2gl1_hdl *fl1, GsmL1_PhRaInd_t *ra_ind,
struct ph_rach_ind_param rach_ind_param;
/* FIXME: this should be deprecated/obsoleted as it bypasses rach.busy counting */
if (ra_ind->measParam.fLinkQuality < bts->min_qual_rach) {
if (ra_ind->measParam.fLinkQuality * 10 < bts->min_qual_rach) {
msgb_free(l1p_msg);
return 0;
}

2
src/osmo-bts-sysmo/l1_if.c
View File

@ -998,7 +998,7 @@ static int handle_ph_ra_ind(struct femtol1_hdl *fl1, GsmL1_PhRaInd_t *ra_ind,
struct ph_rach_ind_param rach_ind_param;
/* FIXME: this should be deprecated/obsoleted as it bypasses rach.busy counting */
if (ra_ind->measParam.fLinkQuality < bts->min_qual_rach) {
if (ra_ind->measParam.fLinkQuality * 10 < bts->min_qual_rach) {
msgb_free(l1p_msg);
return 0;
}