Change in ...osmo-bts[master]: Clarify and refactor link quality (C/I) handling

laforge gerrit-no-reply at lists.osmocom.org
Sun Jul 21 13:51:57 UTC 2019


laforge has submitted this change and it was merged. ( https://gerrit.osmocom.org/c/osmo-bts/+/14686 )

Change subject: Clarify and refactor link quality (C/I) handling
......................................................................

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
---
M doc/manuals/vty/bts_vty_reference.xml
M include/osmo-bts/gsm_data_shared.h
M src/common/bts.c
M src/common/l1sap.c
M src/common/pcu_sock.c
M src/common/vty.c
M src/osmo-bts-litecell15/l1_if.c
M src/osmo-bts-oc2g/l1_if.c
M src/osmo-bts-sysmo/l1_if.c
9 files changed, 22 insertions(+), 22 deletions(-)

Approvals:
  laforge: Looks good to me, approved
  pespin: Looks good to me, but someone else must approve
  Jenkins Builder: Verified



diff --git a/doc/manuals/vty/bts_vty_reference.xml b/doc/manuals/vty/bts_vty_reference.xml
index b50ac1b..4697ee7 100644
--- a/doc/manuals/vty/bts_vty_reference.xml
+++ b/doc/manuals/vty/bts_vty_reference.xml
@@ -1613,14 +1613,14 @@
     </command>
     <command id='min-qual-rach <-100-100>'>
       <params>
-        <param name='min-qual-rach' doc='Set the minimum quality level of RACH burst to be accpeted' />
-        <param name='<-100-100>' 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='<-100-100>' doc='C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)' />
       </params>
     </command>
     <command id='min-qual-norm <-100-100>'>
       <params>
-        <param name='min-qual-norm' doc='Set the minimum quality level of normal burst to be accpeted' />
-        <param name='<-100-100>' 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='<-100-100>' doc='C/I (Carrier-to-Interference) ratio in centiBels (10e-2 B or 10e-1 dB)' />
       </params>
     </command>
     <command id='nominal-tx-power <0-100>'>
diff --git a/include/osmo-bts/gsm_data_shared.h b/include/osmo-bts/gsm_data_shared.h
index a4e326a..dd2a14c 100644
--- a/include/osmo-bts/gsm_data_shared.h
+++ b/include/osmo-bts/gsm_data_shared.h
@@ -759,8 +759,8 @@
 	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 {
diff --git a/src/common/bts.c b/src/common/bts.c
index f582ebd..5c415e8 100644
--- a/src/common/bts.c
+++ b/src/common/bts.c
@@ -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);
 
diff --git a/src/common/l1sap.c b/src/common/l1sap.c
index b730b85..79af8e2 100644
--- a/src/common/l1sap.c
+++ b/src/common/l1sap.c
@@ -1218,7 +1218,7 @@
 	 * 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,
diff --git a/src/common/pcu_sock.c b/src/common/pcu_sock.c
index 1d9fa72..36cc6ed 100644
--- a/src/common/pcu_sock.c
+++ b/src/common/pcu_sock.c
@@ -330,8 +330,8 @@
 	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;
 	}
diff --git a/src/common/vty.c b/src/common/vty.c
index f4fc181..e4f5a16 100644
--- a/src/common/vty.c
+++ b/src/common/vty.c
@@ -300,9 +300,9 @@
 		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_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;
 }
diff --git a/src/osmo-bts-litecell15/l1_if.c b/src/osmo-bts-litecell15/l1_if.c
index 3710fa8..77b72bd 100644
--- a/src/osmo-bts-litecell15/l1_if.c
+++ b/src/osmo-bts-litecell15/l1_if.c
@@ -1004,7 +1004,7 @@
 	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;
 	}
diff --git a/src/osmo-bts-oc2g/l1_if.c b/src/osmo-bts-oc2g/l1_if.c
index d9c8da0..9affc89 100644
--- a/src/osmo-bts-oc2g/l1_if.c
+++ b/src/osmo-bts-oc2g/l1_if.c
@@ -1060,7 +1060,7 @@
 	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;
 	}
diff --git a/src/osmo-bts-sysmo/l1_if.c b/src/osmo-bts-sysmo/l1_if.c
index c431e49..58fc24e 100644
--- a/src/osmo-bts-sysmo/l1_if.c
+++ b/src/osmo-bts-sysmo/l1_if.c
@@ -998,7 +998,7 @@
 	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;
 	}

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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: If624d6fdc0270e6813af8700d95f1345903c8a01
Gerrit-Change-Number: 14686
Gerrit-PatchSet: 7
Gerrit-Owner: fixeria <axilirator at gmail.com>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: fixeria <axilirator at gmail.com>
Gerrit-Reviewer: ipse <Alexander.Chemeris at gmail.com>
Gerrit-Reviewer: laforge <laforge at gnumonks.org>
Gerrit-Reviewer: pespin <pespin at sysmocom.de>
Gerrit-MessageType: merged
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