[M] Change in osmo-bts[master]: meas: lchan_meas_sub_num_expected(): proper cmode enforcement - gerrit-log

30 Sep 2023

fixeria has uploaded this change for review. ( https://gerrit.osmocom.org/c/osmo-bts/+/34592?usp=email )
Change subject: meas: lchan_meas_sub_num_expected(): proper cmode enforcement
......................................................................
meas: lchan_meas_sub_num_expected(): proper cmode enforcement
3GPP TS 45.008, section 8.3 defines TDMA Fn subsets, which shall
always be transmitted when DTX is employed, only for:
* TCH/F in signalling mode (but not for TCH/H),
* TCH/H and TCH/F in data mode (CSD) [*],
* TCH/FS, TCH/EFS, and TCH/HS.
For channel modes employing AMR codec, in particular:
* TCH/AFS, TCH/WFS, O-TCH/WFS,
* TCH/AHS, O-TCH/AHS, O-TCH/WHS,
there exist no fixed TDMA Fn subsets, but DTX is still permitted.
For those we expect at least one SACCH frame, plus a variable
number of speech frames (0 or more).
[*] Handling of data modes is fixed in a follow-up patch.
Change-Id: Ied477528d77871dd7e3b5b7b433a4e33bca40011
Related: OS#6168
---
M src/common/measurement.c
1 file changed, 69 insertions(+), 52 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/osmo-bts refs/changes/92/34592/1

diff --git a/src/common/measurement.c b/src/common/measurement.c
index 6ecd797..fb3c4e9 100644
--- a/src/common/measurement.c
+++ b/src/common/measurement.c
@@ -417,32 +417,38 @@
 }
/* In DTX a subset of blocks must always be transmitted
- * See also: GSM 05.08, chapter 8.3 Aspects of discontinuous transmission (DTX) */
-static unsigned int lchan_meas_sub_num_expected(const struct gsm_lchan *lchan)
+ * See also: GSM 05.08, chapter 8.3 Aspects of discontinuous transmission (DTX)
+ * Return value N: (N < 0) -- at least N SUB frames expected;
+ * 		   (N > 0) -- exactly N SUB frames expected;
+ * 		   (N == 0) - unknown channel type/mode? */
+static int lchan_meas_sub_num_expected(const struct gsm_lchan *lchan)
 {
    enum gsm_phys_chan_config pchan = ts_pchan(lchan->ts);
-	/* AMR is using a more elaborated model with a dymanic amount of
-	 * DTX blocks so this function is not applicable to determine the
-	 * amount of expected SUB Measurements when AMR is used */
-	OSMO_ASSERT(lchan->tch_mode != GSM48_CMODE_SPEECH_AMR);
-
    switch (pchan) {
    case GSM_PCHAN_TCH_F:
-		if (lchan->tch_mode == GSM48_CMODE_SIGN) {
-			/* 1 block SACCH, 24 blocks TCH (see note 1) */
-			return 25;
-		} else {
-			/* 1 block SACCH, 1 block TCH */
-			return 2;
+		switch (lchan->tch_mode) {
+		case GSM48_CMODE_SIGN: /* TCH/F sign: DTX *is* permitted */
+		case GSM48_CMODE_SPEECH_V1: /* TCH/FS */
+		case GSM48_CMODE_SPEECH_EFR: /* TCH/EFS */
+			return 1 + 1; /* 1 x SACCH + 1 x TCH */
+		case GSM48_CMODE_SPEECH_AMR: /* TCH/AFS */
+		case GSM48_CMODE_SPEECH_V4: /* O-TCH/WFS */
+		case GSM48_CMODE_SPEECH_V5: /* TCH/WFS */
+		default:
+			return -1; /* at least 1 x SACCH + M x TCH (variable) */
    	}
    case GSM_PCHAN_TCH_H:
-		if (lchan->tch_mode == GSM48_CMODE_SIGN) {
-			/* 1 block SACCH, 12 blocks TCH (see ynote 1) */
-			return 13;
-		} else {
-			/* 1 block SACCH, 2 blocks TCH */
-			return 3;
+		switch (lchan->tch_mode) {
+		case GSM48_CMODE_SIGN: /* TCH/H sign: DTX *is not* permitted */
+			return 1 + 12; /* 1 x SACCH + 12 x TCH */
+		case GSM48_CMODE_SPEECH_V1:
+			return 1 + 2; /* 1 x SACCH + 2 x TCH */
+		case GSM48_CMODE_SPEECH_AMR: /* TCH/AHS */
+		case GSM48_CMODE_SPEECH_V4: /* O-TCH/WHS */
+		case GSM48_CMODE_SPEECH_V6: /* O-TCH/AHS */
+		default:
+			return -1; /* at least 1 x SACCH + M x TCH (variable) */
    	}
    case GSM_PCHAN_SDCCH8_SACCH8C:
    case GSM_PCHAN_SDCCH8_SACCH8C_CBCH:
@@ -455,8 +461,6 @@
    default:
    	return 0;
    }
-
-	/* Note 1: In signalling mode all blocks count as SUB blocks. */
 }
/* if we clip the TOA value to 12 bits, i.e. toa256=3200,
@@ -562,7 +566,7 @@
    unsigned int num_meas_sub = 0;
    unsigned int num_meas_sub_actual = 0;
    unsigned int num_meas_sub_subst = 0;
-	unsigned int num_meas_sub_expect;
+	int num_meas_sub_expect;
    unsigned int num_ul_meas;
    unsigned int num_ul_meas_actual = 0;
    unsigned int num_ul_meas_subst = 0;
@@ -582,16 +586,7 @@
     * intentionally to save energy. It is not necessarly an error
     * when we get less measurements as we expect. */
    num_ul_meas_expect = lchan_meas_num_expected(lchan);
-
-	if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR)
-		num_meas_sub_expect = lchan_meas_sub_num_expected(lchan);
-	else {
-		/* When AMR is used, we expect at least one SUB frame, since
-		 * the SACCH will always be SUB frame. There may occur more
-		 * SUB frames but since DTX periods in AMR are dynamic, we
-		 * can not know how many exactly. */
-		num_meas_sub_expect = 1;
-	}
+	num_meas_sub_expect = lchan_meas_sub_num_expected(lchan);
if (lchan->meas.num_ul_meas > num_ul_meas_expect)
    	num_ul_meas_excess = lchan->meas.num_ul_meas - num_ul_meas_expect;
@@ -637,11 +632,8 @@
    	} else {
    		m = &measurement_dummy;
-			/* For AMR the amount of SUB frames is defined by the
-			 * the occurrence of DTX periods, which are dynamically
-			 * negotiated in AMR, so we can not know if and how many
-			 * SUB frames are missing. */
-			if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR) {
+			/* only if we know the exact number of SUB measurements */
+			if (num_meas_sub_expect >= 0) {
    			if (num_meas_sub <= i) {
    				num_meas_sub_subst++;
    				is_sub = true;
@@ -658,16 +650,6 @@
    	}
    }
-	if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR) {
-		LOGPLCHAN(lchan, DMEAS, LOGL_DEBUG,
-			  "Received UL measurements contain %u SUB measurements, expected %u\n",
-			  num_meas_sub_actual, num_meas_sub_expect);
-	} else {
-		LOGPLCHAN(lchan, DMEAS, LOGL_DEBUG,
-			  "Received UL measurements contain %u SUB measurements, expected at least %u\n",
-			  num_meas_sub_actual, num_meas_sub_expect);
-	}
-
    LOGPLCHAN(lchan, DMEAS, LOGL_DEBUG, "Replaced %u measurements with dummy values, "
    	  "from which %u were SUB measurements\n", num_ul_meas_subst, num_meas_sub_subst);
@@ -678,17 +660,24 @@
     * above only adds missing measurements during the calculation
     * it can not remove excess SUB measurements or add missing SUB
     * measurements when there is no more room in the interval. */
-	if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR) {
-		if (num_meas_sub != num_meas_sub_expect) {
+	if (num_meas_sub_expect < 0) {
+		num_meas_sub_expect = -num_meas_sub_expect;
+		LOGPLCHAN(lchan, DMEAS, LOGL_DEBUG,
+			  "Received UL measurements contain %u SUB measurements, expected at least %d\n",
+			  num_meas_sub_actual, num_meas_sub_expect);
+		if (OSMO_UNLIKELY(num_meas_sub < num_meas_sub_expect)) {
    		LOGPLCHAN(lchan, DMEAS, LOGL_ERROR,
    			  "Incorrect number of SUB measurements detected! "
-				  "(%u vs exp %u)\n", num_meas_sub, num_meas_sub_expect);
+				  "(%u vs exp >=%d)\n", num_meas_sub, num_meas_sub_expect);
    	}
    } else {
-		if (num_meas_sub < num_meas_sub_expect) {
+		LOGPLCHAN(lchan, DMEAS, LOGL_DEBUG,
+			  "Received UL measurements contain %u SUB measurements, expected %d\n",
+			  num_meas_sub_actual, num_meas_sub_expect);
+		if (OSMO_UNLIKELY(num_meas_sub != num_meas_sub_expect)) {
    		LOGPLCHAN(lchan, DMEAS, LOGL_ERROR,
    			  "Incorrect number of SUB measurements detected! "
-				  "(%u vs exp >=%u)\n", num_meas_sub, num_meas_sub_expect);
+				  "(%u vs exp %d)\n", num_meas_sub, num_meas_sub_expect);
    	}
    }
-- 
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Gerrit-Project: osmo-bts
Gerrit-Branch: master
Gerrit-Change-Id: Ied477528d77871dd7e3b5b7b433a4e33bca40011
Gerrit-Change-Number: 34592
Gerrit-PatchSet: 1
Gerrit-Owner: fixeria vyanitskiy@sysmocom.de
Gerrit-MessageType: newchange



    