EDGE: Fix UL link adaptation.

We have seen that UL MCS5- MCS9 link adaptation has not been implemented in current PCU implementation.
If the MS slowly moves far away from the BTS, the UL MCS will always stick at MCS9 no matter UL link quality values leading to poor data service experience.
The UL MCS is expected to adapt from MCS9 -> MCSx due to bad UL quality.

Below PCU traces indicate that UL MCS is quickly increasing to MCS9 (max MCS 9 was used in this test) and it never changes to other UL MCS due zero thresholds.

<0004> gprs_ms.cpp:670 MS (IMSI ): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-6 -> MCS-7
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-7 -> MCS-8
<0004> gprs_ms.cpp:670 MS (IMSI 000): Link quality 23dB (23dB) left window [0, 0], modifying uplink CS level: MCS-8 -> MCS-9

Change-Id: I9272c337ad6399da4a47cc6e2736e25f24e099d8

4 files changed, 100 insertions, 5 deletions

diff --git a/src/bts.h b/src/bts.h
index 1f1dae25..b1fb8cca 100644
--- a/src/bts.h
+++ b/src/bts.h
@@ -221,6 +221,7 @@ struct gprs_rlcmac_bts {
 	uint8_t cs_adj_upper_limit;
 	uint8_t cs_adj_lower_limit;
 	struct {int16_t low; int16_t high; } cs_lqual_ranges[MAX_GPRS_CS];
+	struct {int16_t low; int16_t high; } mcs_lqual_ranges[MAX_GPRS_CS];
 	uint16_t cs_downgrade_threshold; /* downgrade if less packets left (DL) */
 	uint16_t ws_base;
 	uint16_t ws_pdch; /* increase WS by this value per PDCH */
diff --git a/src/gprs_ms.cpp b/src/gprs_ms.cpp
index c6b7e34b..66312fa9 100644
--- a/src/gprs_ms.cpp
+++ b/src/gprs_ms.cpp
@@ -624,7 +624,7 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 	bts_data = m_bts->bts_data();
 
 	if (!max_cs_ul) {
-		LOGP(DRLCMACDL, LOGL_ERROR,
+		LOGP(DRLCMACMEAS, LOGL_ERROR,
 			"max_cs_ul cannot be derived (current UL CS: %s)\n",
 			m_current_cs_ul.name());
 		return;
@@ -642,11 +642,10 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 		low  = bts_data->cs_lqual_ranges[current_cs_num-1].low;
 		high = bts_data->cs_lqual_ranges[current_cs_num-1].high;
 	} else if (m_current_cs_ul.isEgprs()) {
-		/* TODO, use separate table */
 		if (current_cs_num > MAX_GPRS_CS)
 			current_cs_num = MAX_GPRS_CS;
-		low  = bts_data->cs_lqual_ranges[current_cs_num-1].low;
-		high = bts_data->cs_lqual_ranges[current_cs_num-1].high;
+		low  = bts_data->mcs_lqual_ranges[current_cs_num-1].low;
+		high = bts_data->mcs_lqual_ranges[current_cs_num-1].high;
 	} else {
 		return;
 	}
@@ -661,7 +660,7 @@ void GprsMs::update_cs_ul(const pcu_l1_meas *meas)
 		new_cs_ul.inc(mode());
 
 	if (m_current_cs_ul != new_cs_ul) {
-		LOGP(DRLCMACDL, LOGL_INFO,
+		LOGP(DRLCMACMEAS, LOGL_INFO,
 			"MS (IMSI %s): "
 			"Link quality %ddB (%ddB) left window [%d, %d], "
 			"modifying uplink CS level: %s -> %s\n",
diff --git a/src/pcu_main.cpp b/src/pcu_main.cpp
index 8e7cde80..e909b754 100644
--- a/src/pcu_main.cpp
+++ b/src/pcu_main.cpp
@@ -200,6 +200,28 @@ int main(int argc, char *argv[])
 	bts->cs_lqual_ranges[2].high = 13;
 	bts->cs_lqual_ranges[3].low = 12;
 	bts->cs_lqual_ranges[3].high = 256;
+
+	/* MCS-1 to MCS-9 */
+	/* Default thresholds are referenced from literature */
+	/* Fig. 2.3, Chapter 2, Optimizing Wireless Communication Systems, Springer (2009) */
+	bts->mcs_lqual_ranges[0].low = -256;
+	bts->mcs_lqual_ranges[0].high = 6;
+	bts->mcs_lqual_ranges[1].low = 5;
+	bts->mcs_lqual_ranges[1].high = 8;
+	bts->mcs_lqual_ranges[2].low = 7;
+	bts->mcs_lqual_ranges[2].high = 13;
+	bts->mcs_lqual_ranges[3].low = 12;
+	bts->mcs_lqual_ranges[3].high = 15;
+	bts->mcs_lqual_ranges[4].low = 14;
+	bts->mcs_lqual_ranges[4].high = 17;
+	bts->mcs_lqual_ranges[5].low = 16;
+	bts->mcs_lqual_ranges[5].high = 18;
+	bts->mcs_lqual_ranges[6].low = 17;
+	bts->mcs_lqual_ranges[6].high = 20;
+	bts->mcs_lqual_ranges[7].low = 19;
+	bts->mcs_lqual_ranges[7].high = 24;
+	bts->mcs_lqual_ranges[8].low = 23;
+	bts->mcs_lqual_ranges[8].high = 256;
 	bts->cs_downgrade_threshold = 200;
 
 	/* TODO: increase them when CRBB decoding is implemented */
diff --git a/src/pcu_vty.c b/src/pcu_vty.c
index 68d2f556..5ec16eaf 100644
--- a/src/pcu_vty.c
+++ b/src/pcu_vty.c
@@ -178,6 +178,25 @@ static int config_write_pcu(struct vty *vty)
 		bts->cs_lqual_ranges[3].low,
 		VTY_NEWLINE);
 
+	vty_out(vty, " mcs link-quality-ranges mcs1 %d mcs2 %d %d mcs3 %d %d mcs4 %d %d mcs5 %d %d mcs6 %d %d mcs7 %d %d mcs8 %d %d mcs9 %d%s",
+		bts->mcs_lqual_ranges[0].high,
+		bts->mcs_lqual_ranges[1].low,
+		bts->mcs_lqual_ranges[1].high,
+		bts->mcs_lqual_ranges[2].low,
+		bts->mcs_lqual_ranges[2].high,
+		bts->mcs_lqual_ranges[3].low,
+		bts->mcs_lqual_ranges[3].high,
+		bts->mcs_lqual_ranges[4].low,
+		bts->mcs_lqual_ranges[4].high,
+		bts->mcs_lqual_ranges[5].low,
+		bts->mcs_lqual_ranges[5].high,
+		bts->mcs_lqual_ranges[6].low,
+		bts->mcs_lqual_ranges[6].high,
+		bts->mcs_lqual_ranges[7].low,
+		bts->mcs_lqual_ranges[7].high,
+		bts->mcs_lqual_ranges[8].low,
+		VTY_NEWLINE);
+
 	if (bts->initial_mcs_dl != 1 && bts->initial_mcs_ul != 1) {
 		if (bts->initial_mcs_ul == bts->initial_mcs_dl)
 			vty_out(vty, " mcs %d%s", bts->initial_mcs_dl,
@@ -186,6 +205,7 @@ static int config_write_pcu(struct vty *vty)
 			vty_out(vty, " mcs %d %d%s", bts->initial_mcs_dl,
 				bts->initial_mcs_ul, VTY_NEWLINE);
 	}
+
 	if (bts->max_mcs_dl && bts->max_mcs_ul) {
 		if (bts->max_mcs_ul == bts->max_mcs_dl)
 			vty_out(vty, " mcs max %d%s", bts->max_mcs_dl,
@@ -969,6 +989,58 @@ DEFUN(cfg_pcu_cs_lqual_ranges,
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_pcu_mcs_lqual_ranges,
+      cfg_pcu_mcs_lqual_ranges_cmd,
+      "mcs link-quality-ranges mcs1 <0-35> mcs2 <0-35> <0-35> mcs3 <0-35> <0-35> mcs4 <0-35> <0-35> mcs5 <0-35> <0-35> mcs6 <0-35> <0-35> mcs7 <0-35> <0-35> mcs8 <0-35> <0-35> mcs9 <0-35>",
+      CS_STR "Set link quality ranges\n"
+      "Set quality range for MCS-1 (high value only)\n"
+      "MCS-1 high (dB)\n"
+      "Set quality range for MCS-2\n"
+      "MCS-2 high (dB)\n"
+      "MCS-2 low (dB)\n"
+      "Set quality range for MCS-3\n"
+      "MCS-3 high (dB)\n"
+      "MCS-3 low (dB)\n"
+      "Set quality range for MCS-4\n"
+      "MCS-4 high (dB)\n"
+      "MCS-4 low (dB)\n"
+      "Set quality range for MCS-5\n"
+      "MCS-5 high (dB)\n"
+      "MCS-5 low (dB)\n"
+      "Set quality range for MCS-6\n"
+      "MCS-6 low (dB)\n"
+      "MCS-6 high (dB)\n"
+      "Set quality range for MCS-7\n"
+      "MCS-7 low (dB)\n"
+      "MCS-7 high (dB)\n"
+      "Set quality range for MCS-8\n"
+      "MCS-8 low (dB)\n"
+      "MCS-8 high (dB)\n"
+      "Set quality range for MCS-9 (low value only)\n"
+      "MCS-9 low (dB)\n")
+{
+	struct gprs_rlcmac_bts *bts = bts_main_data();
+
+	bts->mcs_lqual_ranges[0].high = atoi(argv[0]);
+	bts->mcs_lqual_ranges[1].low  = atoi(argv[1]);
+	bts->mcs_lqual_ranges[1].high = atoi(argv[2]);
+	bts->mcs_lqual_ranges[2].low  = atoi(argv[3]);
+	bts->mcs_lqual_ranges[2].high = atoi(argv[4]);
+	bts->mcs_lqual_ranges[3].low  = atoi(argv[5]);
+	bts->mcs_lqual_ranges[3].high  = atoi(argv[6]);
+	bts->mcs_lqual_ranges[4].low  = atoi(argv[7]);
+	bts->mcs_lqual_ranges[4].high  = atoi(argv[8]);
+	bts->mcs_lqual_ranges[5].low  = atoi(argv[9]);
+	bts->mcs_lqual_ranges[5].high  = atoi(argv[10]);
+	bts->mcs_lqual_ranges[6].low  = atoi(argv[11]);
+	bts->mcs_lqual_ranges[6].high  = atoi(argv[12]);
+	bts->mcs_lqual_ranges[7].low  = atoi(argv[13]);
+	bts->mcs_lqual_ranges[7].high  = atoi(argv[14]);
+	bts->mcs_lqual_ranges[8].low  = atoi(argv[15]);
+
+	return CMD_SUCCESS;
+}
+
 DEFUN(cfg_pcu_sock,
       cfg_pcu_sock_cmd,
       "pcu-socket PATH",
@@ -1079,6 +1151,7 @@ int pcu_vty_init(const struct log_info *cat)
 	install_element(PCU_NODE, &cfg_pcu_cs_downgrade_thrsh_cmd);
 	install_element(PCU_NODE, &cfg_pcu_no_cs_downgrade_thrsh_cmd);
 	install_element(PCU_NODE, &cfg_pcu_cs_lqual_ranges_cmd);
+	install_element(PCU_NODE, &cfg_pcu_mcs_lqual_ranges_cmd);
 	install_element(PCU_NODE, &cfg_pcu_mcs_cmd);
 	install_element(PCU_NODE, &cfg_pcu_dl_arq_cmd);
 	install_element(PCU_NODE, &cfg_pcu_no_mcs_cmd);