measurement: expect at least 1 SUB frame for AMR

The amount of SUB frames that may occur in AMR is not fixed, nor can it
be determined by some formular or lookup table. The reason for this is
that the DTX period may negotiated dynamicly. This means that the lower
layers must make the decision if an AMR sub frame is a SUB frame early
and tag the repective measurement / frame they hand up to the upper
layers accordingly. However, regardles of the occurrence of DTX periods
the amount of SUB frames in AMR must be always 1 or more because SACCH
frames always count as SUB frames as well. Lets make sure that this is
respected in the debug log as well as in the logic that tries to
substitue missing SUB frame measuremnets.

Change-Id: I1fd91b576ff7274caa6d4356bcd7a4fa4311219d
Related: OS#4465

1 files changed, 48 insertions, 19 deletions

diff --git a/src/common/measurement.c b/src/common/measurement.c
index 3ee9ffe7..3170e4a1 100644
--- a/src/common/measurement.c
+++ b/src/common/measurement.c
@@ -571,10 +571,11 @@ int lchan_meas_check_compute(struct gsm_lchan *lchan, uint32_t fn)
 	if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR)
 		num_meas_sub_expect = lchan_meas_sub_num_expected(lchan);
 	else {
-		/* FIXME: the amount of SUB Measurements is a dynamic parameter
-		 * in AMR and can not be determined by using a lookup table.
-		 * See also: OS#2978 */
-		num_meas_sub_expect = 0;
+		/* 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 much exactly. */
+		num_meas_sub_expect = 1;
 	}
 
 	if (lchan->meas.num_ul_meas > num_ul_meas_expect)
@@ -618,9 +619,16 @@ int lchan_meas_check_compute(struct gsm_lchan *lchan, uint32_t fn)
 			num_ul_meas_actual++;
 		} else {
 			m = &measurement_dummy;
-			if (num_ul_meas_expect - i <= num_meas_sub_expect - num_meas_sub) {
-				num_meas_sub_subst++;
-				is_sub = true;
+
+			/* 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) {
+				if (num_ul_meas_expect - i <= num_meas_sub_expect - num_meas_sub) {
+					num_meas_sub_subst++;
+					is_sub = true;
+				}
 			}
 
 			num_ul_meas_subst++;
@@ -633,21 +641,42 @@ int lchan_meas_check_compute(struct gsm_lchan *lchan, uint32_t fn)
 		}
 	}
 
-	LOGP(DMEAS, LOGL_DEBUG, "%s received UL measurements contain %u SUB measurements, expected %u\n",
-	     gsm_lchan_name(lchan), num_meas_sub_actual, num_meas_sub_expect);
+	if (lchan->tch_mode != GSM48_CMODE_SPEECH_AMR) {
+		LOGP(DMEAS, LOGL_DEBUG,
+		     "%s received UL measurements contain %u SUB measurements, expected %u\n",
+		     gsm_lchan_name(lchan), num_meas_sub_actual,
+		     num_meas_sub_expect);
+	} else {
+		LOGP(DMEAS, LOGL_DEBUG,
+		     "%s received UL measurements contain %u SUB measurements, expected at least %u\n",
+		     gsm_lchan_name(lchan), num_meas_sub_actual,
+		     num_meas_sub_expect);
+	}
+
 	LOGP(DMEAS, LOGL_DEBUG, "%s replaced %u measurements with dummy values, from which %u were SUB measurements\n",
 	     gsm_lchan_name(lchan), num_ul_meas_subst, num_meas_sub_subst);
 
-	if (num_meas_sub != num_meas_sub_expect) {
-		LOGP(DMEAS, LOGL_ERROR, "%s Incorrect number of SUB measurements detected! (%u vs exp %u)\n",
-		     gsm_lchan_name(lchan), num_meas_sub, num_meas_sub_expect);
-		/* Normally the logic above should make sure that there is
-		 * always the exact amount of SUB measurements taken into
-		 * account. If not then the logic that decides tags the received
-		 * measurements as is_sub works incorrectly. Since the logic
-		 * 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. */
+	/* Normally the logic above should make sure that there is
+	 * always the exact amount of SUB measurements taken into
+	 * account. If not then the logic that decides tags the received
+	 * measurements as is_sub works incorrectly. Since the logic
+	 * 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) {
+			LOGP(DMEAS, LOGL_ERROR,
+			     "%s Incorrect number of SUB measurements detected! (%u vs exp %u)\n",
+			     gsm_lchan_name(lchan), num_meas_sub,
+			     num_meas_sub_expect);
+		}
+	} else {
+		if (num_meas_sub < num_meas_sub_expect) {
+			LOGP(DMEAS, LOGL_ERROR,
+			     "%s Incorrect number of SUB measurements detected! (%u vs exp >=%u)\n",
+			     gsm_lchan_name(lchan), num_meas_sub,
+			     num_meas_sub_expect);
+		}
 	}
 
 	/* Measurement computation step 2: divide */