implement baseic uplink measurement processing + reporting

* gather measurements from each PH-DATA.ind
* check every TDMA frame about meas period expiration
* compute averages after period expired
* put MS DL MEAS REP into RSL MEAS RES messages, include UL meas

bugs:
* L3 INFO content seems to have some offset
* is_sub is not set anywhere
* measurement periods might have up/downlink offset

1 files changed, 235 insertions, 0 deletions

diff --git a/src/common/measurement.c b/src/common/measurement.c
new file mode 100644
index 00000000..c20db46f
--- /dev/null
+++ b/src/common/measurement.c
@@ -0,0 +1,235 @@
+
+#include <stdint.h>
+#include <errno.h>
+
+#include <osmocom/gsm/gsm_utils.h>
+
+#include <osmo-bts/gsm_data.h>
+#include <osmo-bts/logging.h>
+#include <osmo-bts/measurement.h>
+
+/* TS 05.08, Chapter 8.4.1 */
+/* measurement period ends at fn % 104 == ? */
+static const uint8_t tchf_meas_rep_fn104[] = {
+	[0] =	103,
+	[1] =	12,
+	[2] =	25,
+	[3] =	38,
+	[4] =	51,
+	[5] =	64,
+	[6] =	77,
+	[7] =	90,
+};
+static const uint8_t tchh0_meas_rep_fn104[] = {
+	[0] =	103,
+	[1] =	103,
+	[2] =	25,
+	[3] =	25,
+	[4] =	51,
+	[5] =	51,
+	[6] =	77,
+	[7] =	77,
+};
+static const uint8_t tchh1_meas_rep_fn104[] = {
+	[0] =	12,
+	[1] =	12,
+	[2] =	38,
+	[3] =	38,
+	[4] =	64,
+	[5] =	64,
+	[6] =	90,
+	[7] =	90,
+};
+
+/* determine if a measurement period ends at the given frame number */
+static int is_meas_complete(enum gsm_phys_chan_config pchan, unsigned int ts,
+			    unsigned int subch, uint32_t fn)
+{
+	unsigned int fn_mod;
+	const uint8_t *tbl;
+	int rc = 0;
+
+	if (ts >= 8)
+		return -EINVAL;
+	if (pchan >= _GSM_PCHAN_MAX)
+		return -EINVAL;
+
+	switch (pchan) {
+	case GSM_PCHAN_TCH_F:
+		fn_mod = fn % 104;
+		if (tchf_meas_rep_fn104[ts] == fn_mod)
+			rc = 1;
+		break;
+	case GSM_PCHAN_TCH_H:
+		fn_mod = fn % 104;
+		if (subch == 0)	
+			tbl = tchh0_meas_rep_fn104;
+		else
+			tbl = tchh1_meas_rep_fn104;
+		if (tbl[ts] == fn_mod)
+			rc = 1;
+		break;
+	case GSM_PCHAN_SDCCH8_SACCH8C:
+		fn_mod = fn % 102;
+		if (fn_mod == 11)
+			rc = 1;
+		break;
+	case GSM_PCHAN_CCCH_SDCCH4:
+		fn_mod = fn % 102;
+		if (fn_mod == 36)
+			rc = 1;
+		break;
+	default:
+		rc = 0;
+		break;
+	}
+	return rc;
+}
+
+/* receive a L1 uplink measurement from L1 */
+int lchan_new_ul_meas(struct gsm_lchan *lchan, struct bts_ul_meas *ulm)
+{
+	DEBUGP(DMEAS, "%s adding measurement, num_ul_meas=%d\n",
+		gsm_lchan_name(lchan), lchan->meas.num_ul_meas);
+
+	if (lchan->meas.num_ul_meas >= ARRAY_SIZE(lchan->meas.uplink)) {
+		LOGP(DMEAS, LOGL_NOTICE, "%s no space for uplink measurement\n",
+			gsm_lchan_name(lchan));
+		return -ENOSPC;
+	}
+
+	memcpy(&lchan->meas.uplink[lchan->meas.num_ul_meas++], ulm,
+		sizeof(*ulm));
+
+	return 0;
+}
+
+/* input: BER in steps of .01%, i.e. percent/100 */
+static uint8_t ber10k_to_rxqual(uint32_t ber10k)
+{
+	/* 05.08 / 8.2.4 */
+	if (ber10k < 20)
+		return 0;
+	if (ber10k < 40)
+		return 1;
+	if (ber10k < 80)
+		return 2;
+	if (ber10k < 160)
+		return 3;
+	if (ber10k < 320)
+		return 4;
+	if (ber10k < 640)
+		return 5;
+	if (ber10k < 1280)
+		return 6;
+	return 7;
+}
+
+int lchan_meas_check_compute(struct gsm_lchan *lchan, uint32_t fn)
+{
+	uint32_t ber_full_sum = 0;
+	uint32_t irssi_full_sum = 0;
+	uint32_t ber_sub_sum = 0;
+	uint32_t irssi_sub_sum = 0;
+	int32_t taqb_sum = 0;
+	unsigned int num_meas_sub = 0;
+	int i;
+
+	/* if measurement period is not complete, abort */
+	if (!is_meas_complete(lchan->ts->pchan, lchan->ts->nr,
+			      lchan->nr, fn))
+		return 0;
+
+	/* if there are no measurements, skip computation */
+	if (lchan->meas.num_ul_meas == 0)
+		return 0;
+
+	/* compute the actual measurements */
+
+	/* step 1: add up */
+	for (i = 0; i < lchan->meas.num_ul_meas; i++) {
+		struct bts_ul_meas *m = &lchan->meas.uplink[i];
+
+		ber_full_sum += m->ber10k;
+		irssi_full_sum += m->inv_rssi;
+		taqb_sum += m->ta_offs_qbits;
+
+		if (m->is_sub) {
+			num_meas_sub++;
+			ber_sub_sum += m->ber10k;
+			irssi_sub_sum += m->inv_rssi;
+		}
+	}
+
+	/* step 2: divide */
+	ber_full_sum = ber_full_sum / lchan->meas.num_ul_meas;
+	irssi_full_sum = irssi_full_sum / lchan->meas.num_ul_meas;
+	taqb_sum = taqb_sum / lchan->meas.num_ul_meas;
+	ber_sub_sum = ber_sub_sum / num_meas_sub;
+	irssi_sub_sum = irssi_sub_sum / num_meas_sub;
+
+	DEBUGP(DMEAS, "%s Computed TA(% 4uqb) BER-FULL(%2u.%02u%%), RSSI-FULL(-%3udBm), "
+		"BER-SUB(%2u.%02u%%), RSSI-SUB(-%3udBm)", gsm_lchan_name(lchan),
+		taqb_sum, ber_full_sum/100,
+		ber_full_sum%100, irssi_full_sum, ber_sub_sum/100, ber_sub_sum%100,
+		irssi_sub_sum);
+
+	/* store results */
+	lchan->meas.res.rxlev_full = dbm2rxlev((int)irssi_full_sum * -1);
+	lchan->meas.res.rxlev_sub = dbm2rxlev((int)irssi_sub_sum * -1);
+	lchan->meas.res.rxqual_full = ber10k_to_rxqual(ber_full_sum);
+	lchan->meas.res.rxqual_sub = ber10k_to_rxqual(ber_sub_sum);
+
+	lchan->meas.flags |= LC_UL_M_F_RES_VALID;
+	lchan->meas.num_ul_meas = 0;
+
+	/* send a signal indicating computation is complete */
+
+	return 1;
+}
+
+/* build the 3 byte RSL uplinke measurement IE content */
+int lchan_build_rsl_ul_meas(struct gsm_lchan *lchan, uint8_t *buf)
+{
+	buf[0] = (lchan->meas.res.rxlev_full & 0x3f); /* FIXME: DTXu support */
+	buf[1] = (lchan->meas.res.rxlev_sub & 0x3f);
+	buf[2] = ((lchan->meas.res.rxqual_full & 7) << 3) |
+					(lchan->meas.res.rxqual_sub & 7);
+
+	return 3;
+}
+
+int ts_meas_check_compute(struct gsm_bts_trx_ts *ts, uint32_t fn)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(ts->lchan); i++) {
+		struct gsm_lchan *lchan = &ts->lchan[i];
+
+		if (lchan->state != LCHAN_S_ACTIVE)
+			continue;
+
+		switch (lchan->type) {
+		case GSM_LCHAN_SDCCH:
+		case GSM_LCHAN_TCH_F:
+		case GSM_LCHAN_TCH_H:
+			lchan_meas_check_compute(lchan, fn);
+			break;
+		default:
+			break;
+		}
+	}
+	return 0;
+}
+
+/* needs to be called once every TDMA frame ! */
+int trx_meas_check_compute(struct gsm_bts_trx *trx, uint32_t fn)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(trx->ts); i++) {
+		struct gsm_bts_trx_ts *ts = &trx->ts[i];
+		ts_meas_check_compute(ts, fn);
+	}
+	return 0;
+}