DL AMC based on the SINR report from UE

- get the reported SINR value from the index
- use BLER vs SNR look-up table from dlsim simulation (BLER threshold 10^-3)
- add a flag at gNB from CML to activate AMC
- add additional SINR offset at gNB from CML, to apply to the reported value for DL AMC

executables/nr-softmodem-common.h

@@ -130,13 +130,15 @@
 #define CONFIG_HLP_FI_ScalingFD  "Set the I scaling factor (denominator) of the PID controller for the Doppler compensation at UE side"
 #define CONFIG_HLP_FD_ScalingFN  "Set the D scaling factor (numerator) of the PID controller for the Doppler compensation at UE side"
 #define CONFIG_HLP_FD_ScalingFD  "Set the D scaling factor (denominator) of the PID controller for the Doppler compensation at UE side"
-#define CONFIG_HLP_FO_PScaling "set P scaling factor of the PID controller for the frequency offset compensation"
-#define CONFIG_HLP_FO_IScaling "set I scaling factor of the PID controller for the frequency offset compensation"
-#define CONFIG_HLP_TP_Scaling "set scaling P for TO"
-#define CONFIG_HLP_TI_Scaling "set scaling I for TO"
-#define CONFIG_HLP_TO_Iinit    "Init the I part of the PI controller for timing offset compensation"
+#define CONFIG_HLP_FO_PScaling   "set P scaling factor of the PID controller for the frequency offset compensation"
+#define CONFIG_HLP_FO_IScaling   "set I scaling factor of the PID controller for the frequency offset compensation"
+#define CONFIG_HLP_TP_Scaling    "set scaling P for TO"
+#define CONFIG_HLP_TI_Scaling    "set scaling I for TO"
+#define CONFIG_HLP_TO_Iinit      "Init the I part of the PI controller for timing offset compensation"
 #define CONFIG_HLP_AGC           "Enable Receive Automatic Gain control"
 #define CONFIG_HLP_ULPC          "Enable NR Uplink power control for PUSCH and PUCCH"
+#define CONFIG_HLP_AMC           "flag to use adaptive modulation and coding: 1 = use AMC \n"
+#define CONFIG_HLP_SINR_OSET_DL  "Additional SINR offset in [dB] applied to the reported SINR from UE for DL AMC \n"
 /*--------------------------------------------------------------------------------------------------------------------------------*/
 /*                                            command line parameters for LOG utility                                             */
 /*   optname         helpstr          paramflags          XXXptr                     defXXXval            type           numelt   */

executables/nr-softmodem.h

@@ -42,10 +42,14 @@
   {"PET" ,                  CONFIG_HLP_PathEnd,        0,                .u16ptr=&pathEndingTime,             .defintval=1280,                  TYPE_UINT16, 0},        \
   {"ue_PosY" ,              CONFIG_HLP_uePosY,         0,                .iptr=&uePosY,                       .defintval=0,                     TYPE_INT,    0},        \
   {"FDC" ,                  CONFIG_HLP_FDopplerPrePost,0,                .iptr=&fdopplerPrePost,              .defintval=0,                     TYPE_INT32,  0},        \
-  {"FC" ,                   CONFIG_HLP_FDopplerComp,   0,                .iptr=&fdopplerComp,                 .defintval=0,                     TYPE_INT32,  0}         \
+  {"FC" ,                   CONFIG_HLP_FDopplerComp,   0,                .iptr=&fdopplerComp,                 .defintval=0,                     TYPE_INT32,  0},        \
+  {"amc" ,                  CONFIG_HLP_AMC,            0,                .u8ptr=&amc_flag,                    .defdblval=0,                     TYPE_UINT8,  0},        \
+  {"sinr-offset-dl" ,       CONFIG_HLP_SINR_OSET_DL,   0,                .dblptr=&sinr_offset_dl,             .defdblval=0,                     TYPE_DOUBLE, 0}         \
 }
 // clang-format on
 
+extern uint8_t amc_flag; // flag to use adaptive modulation and coding
+extern double sinr_offset_dl; // additional SINR offset in [dB] applied to the reported SINR from UE for DL AMC
 extern uint32_t target_dl_mcs;
 extern uint32_t target_dl_Nl;
 extern uint32_t target_ul_Nl;

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_dlsch.c

@@ -53,6 +53,13 @@
 #define WORD 32
 //#define SIZE_OF_POINTER sizeof (void *)
 
+// look-up table for AMC. Based on BLER vs SNR curves from the DLsim simulation
+// SNR Thresholds for MCS 0 - 28; with a resolution of 0.5dB; to maintain a BLER of 10^-3;
+//  [min <= ... < max] for each MCS
+const uint8_t Nr_MCS = 29; // 0-28
+float SINR_MCS_mapping[29] = {3,  3,    3.5, 4,  4.5,  5,    5.5, 6,  7,  7.5, 9.5, 10, 11, 11.5, 12.5,
+                              13, 13.5, 15,  16, 16.5, 17.5, 18,  19, 20, 21,  22,  23, 24, 25.5};
+
 const int get_dl_tda(const gNB_MAC_INST *nrmac, const NR_ServingCellConfigCommon_t *scc, int slot) {
 
   /* we assume that this function is mutex-protected from outside */
@@ -583,6 +590,19 @@ static int comparator(const void *p, const void *q) {
   return ((UEsched_t*)p)->coef < ((UEsched_t*)q)->coef;
 }
 
+uint8_t get_MCS_from_SINR(float SINR)
+{
+  for (int i = Nr_MCS - 1; i >= 0; i--) {
+    if (SINR >= SINR_MCS_mapping[i])
+      return i;
+  }
+  LOG_I(MAC, "SINR (%f dB) too low, no MCS possible to achieve BLER of 10^-3\n", SINR);
+  return 0;
+}
+
+extern uint8_t amc_flag; // flag to use adaptive modulation and coding
+extern double sinr_offset_dl; // additional SINR offset in [dB] applied to the reported SINR from UE for DL AMC
+
 static void pf_dl(module_id_t module_id,
                   frame_t frame,
                   sub_frame_t slot,
@@ -657,7 +677,10 @@ static void pf_dl(module_id_t module_id,
       const NR_bler_options_t *bo = &mac->dl_bler;
       const int max_mcs_table = current_BWP->mcsTableIdx == 1 ? 27 : 28;
       const int max_mcs = min(sched_ctrl->dl_max_mcs, max_mcs_table);
-      if (bo->harq_round_max == 1)
+      if (amc_flag) {
+        float SINR = get_measured_sinr(sched_ctrl->CSI_report.ssb_cri_report.SINR);
+        sched_pdsch->mcs = min(get_MCS_from_SINR(SINR + sinr_offset_dl), max_mcs);
+      } else if (bo->harq_round_max == 1)
         sched_pdsch->mcs = max_mcs;
       else
         sched_pdsch->mcs = get_mcs_from_bler(bo, stats, &sched_ctrl->dl_bler_stats, max_mcs, frame);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_phytest.c

@@ -41,6 +41,8 @@ extern RAN_CONTEXT_t RC;
 
 //#define ENABLE_MAC_PAYLOAD_DEBUG 1
 
+uint8_t amc_flag = 0; // flag to use adaptive modulation and coding
+double sinr_offset_dl = 0.0; // additional SINR offset in [dB] applied to the reported SINR from UE for DL AMC
 uint32_t target_dl_mcs = 9;
 uint32_t target_dl_Nl = 1;
 uint32_t target_dl_bw = 50;
@@ -154,7 +156,13 @@ void nr_preprocessor_phytest(module_id_t module_id,
                                                &tda_info,
                                                target_dl_Nl);
 
-  sched_pdsch->mcs = target_dl_mcs;
+  if (amc_flag) {
+    if (sched_ctrl->retrans_dl_harq.head == -1) { // first transmission only
+      float SINR = get_measured_sinr(sched_ctrl->CSI_report.ssb_cri_report.SINR);
+      sched_pdsch->mcs = get_MCS_from_SINR(SINR + sinr_offset_dl);
+    }
+  } else
+    sched_pdsch->mcs = target_dl_mcs;
   sched_pdsch->nrOfLayers = target_dl_Nl;
   sched_pdsch->Qm = nr_get_Qm_dl(sched_pdsch->mcs, dl_bwp->mcsTableIdx);
   sched_pdsch->R = nr_get_code_rate_dl(sched_pdsch->mcs, dl_bwp->mcsTableIdx);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_uci.c

@@ -113,40 +113,51 @@ int ssb_rsrp_sorted[MAX_NUM_SSB] = {0};
 //Stored all the upper limits[Max RSRP Value of corresponding index]
 //stored -1 for invalid values
 static const int L1_SSB_CSI_RSRP_measReport_mapping_38133_10_1_6_1_1[128] = {
-    -1,   -1,   -1,   -1,   -1,      -1,   -1,      -1,   -1,   -1, // 0 - 9
-    -1,   -1,   -1,   -1,   -1,      -1,   INT_MIN, -140, -139, -138, // 10 - 19
-    -137, -136, -135, -134, -133,    -132, -131,    -130, -129, -128, // 20 - 29
-    -127, -126, -125, -124, -123,    -122, -121,    -120, -119, -118, // 30 - 39
-    -117, -116, -115, -114, -113,    -112, -111,    -110, -109, -108, // 40 - 49
-    -107, -106, -105, -104, -103,    -102, -101,    -100, -99,  -98, // 50 - 59
-    -97,  -96,  -95,  -94,  -93,     -92,  -91,     -90,  -89,  -88, // 60 - 69
-    -87,  -86,  -85,  -84,  -83,     -82,  -81,     -80,  -79,  -78, // 70 - 79
-    -77,  -76,  -75,  -74,  -73,     -72,  -71,     -70,  -69,  -68, // 80 - 89
-    -67,  -66,  -65,  -64,  -63,     -62,  -61,     -60,  -59,  -58, // 90 - 99
-    -57,  -56,  -55,  -54,  -53,     -52,  -51,     -50,  -49,  -48, // 100 - 109
-    -47,  -46,  -45,  -44,  INT_MAX, -1,   -1,      -1,   -1,   -1, // 110 - 119
-    -1,   -1,   -1,   -1,   -1,      -1,   -1,      -1 // 120 - 127
+    -1,   -1,   -1,   -1,   -1,      -1,   -1,      -1,   -1,   -1,   //   0 -   9
+    -1,   -1,   -1,   -1,   -1,      -1,   INT_MIN, -140, -139, -138, //  10 -  19
+    -137, -136, -135, -134, -133,    -132, -131,    -130, -129, -128, //  20 -  29
+    -127, -126, -125, -124, -123,    -122, -121,    -120, -119, -118, //  30 -  39
+    -117, -116, -115, -114, -113,    -112, -111,    -110, -109, -108, //  40 -  49
+    -107, -106, -105, -104, -103,    -102, -101,    -100, -99,  -98,  //  50 -  59
+    -97,  -96,  -95,  -94,  -93,     -92,  -91,     -90,  -89,  -88,  //  60 -  69
+    -87,  -86,  -85,  -84,  -83,     -82,  -81,     -80,  -79,  -78,  //  70 -  79
+    -77,  -76,  -75,  -74,  -73,     -72,  -71,     -70,  -69,  -68,  //  80 -  89
+    -67,  -66,  -65,  -64,  -63,     -62,  -61,     -60,  -59,  -58,  //  90 -  99
+    -57,  -56,  -55,  -54,  -53,     -52,  -51,     -50,  -49,  -48,  // 100 - 109
+    -47,  -46,  -45,  -44,  INT_MAX, -1,   -1,      -1,   -1,   -1,   // 110 - 119
+    -1,   -1,   -1,   -1,   -1,      -1,   -1,      -1                // 120 - 127
 };
 
 //Differential RSRP values Table 10.1.6.1-2 from 36.133
 //Stored the upper limits[MAX RSRP Value]
 static const int diff_rsrp_ssb_csi_meas_10_1_6_1_2[16] = {
-    0,
-    -2,
-    -4,
-    -6,
-    -8,
-    -10,
-    -12,
-    -14,
-    -16,
-    -18, // 0 - 9
-    -20,
-    -22,
-    -24,
-    -26,
-    -28,
-    -30 // 10 - 15
+    0,   -2,  -4,  -6,  -8,  -10, -12, -14, -16, -18, //  0 -  9
+    -20, -22, -24, -26, -28, -30                      // 10 - 15
+};
+
+// Measured SINR Values Table 10.1.16.1-1 from 38.133 V16.7.0
+// Stored all the lower limits[Min SINR Value of corresponding index]
+float L1_SSB_CSI_SINR_measReport_mapping_38133_10_1_16_1_1[128] = {
+    INT_MIN, -23, -22.5, -22, -21.5, -21, -20.5, -20, -19.5, -19, //   0 -   9
+    -18.5,   -18, -17.5, -17, -16.5, -16, -15.5, -15, -14.5, -14, //  10 -  19
+    -13.5,   -13, -12.5, -12, -11.5, -11, -10.5, -10, -9.5,  -9,  //  20 -  29
+    -8.5,    -8,  -7.5,  -7,  -6.5,  -6,  -5.5,  -5,  -4.5,  -4,  //  30 -  39
+    -3.5,    -3,  -2.5,  -2,  -1.5,  -1,  -0.5,  0,   0.5,   1,   //  40 -  49
+    1.5,     2,   2.5,   3,   3.5,   4,   4.5,   5,   5.5,   6,   //  50 -  59
+    6.5,     7,   7.5,   8,   8.5,   9,   9.5,   10,  10.5,  11,  //  60 -  69
+    11.5,    12,  12.5,  13,  13.5,  14,  14.5,  15,  15.5,  16,  //  70 -  79
+    16.5,    17,  17.5,  18,  18.5,  19,  19.5,  20,  20.5,  21,  //  80 -  89
+    21.5,    22,  22.5,  23,  23.5,  24,  24.5,  25,  25.5,  26,  //  90 -  99
+    26.5,    27,  27.5,  28,  28.5,  29,  29.5,  30,  30.5,  31,  // 100 - 109
+    31.5,    32,  32.5,  33,  33.5,  34,  34.5,  35,  35.5,  36,  // 110 - 119
+    36.5,    37,  37.5,  38,  38.5,  39,  39.5,  40               // 120 - 127
+};
+
+// Differential SINR values Table 10.1.16.1-2 from 38.133 V16.7.0
+// Stored the upper limits[MAX delta SINR Value]
+int diff_sinr_ssb_csi_meas_10_1_16_1_2[16] = {
+    0,   -1,  -2,  -3,  -4,  -5, -6, -7, -8, -9, //  0 -  9
+    -10, -11, -12, -13, -14, -15                 // 10 - 15
 };
 
 static int get_pucch_index(int frame, int slot, int n_slots_frame, const NR_TDD_UL_DL_Pattern_t *tdd, int sched_pucch_size)
@@ -488,6 +499,18 @@ static int get_diff_rsrp(uint8_t index, int strongest_rsrp) {
     return MIN_RSRP_VALUE;
 }
 
+// returns the measured SINR value (lower limit)
+float get_measured_sinr(uint8_t index)
+{
+  // if index is invalid, return minimum value
+  if (index > 127) {
+    LOG_E(MAC, "%s: invalid SINR report index: %d\n", __func__, index);
+    return INT_MIN; // invalid index
+  }
+
+  return L1_SSB_CSI_SINR_measReport_mapping_38133_10_1_16_1_1[index];
+}
+
 //identifies the target SSB Beam index
 //keeps the required date for PDCCH and PDSCH TCI state activation/deactivation CE consutruction globally
 //handles triggering of PDCCH and PDSCH MAC CEs

openair2/LAYER2/NR_MAC_gNB/mac_proto.h

@@ -455,4 +455,7 @@ void nr_mac_check_ul_failure(const gNB_MAC_INST *nrmac, int rnti, NR_UE_sched_ct
 
 void nr_mac_trigger_reconfiguration(const gNB_MAC_INST *nrmac, const NR_UE_info_t *UE);
 
+float get_measured_sinr(uint8_t index);
+uint8_t get_MCS_from_SINR(float SINR);
+
 #endif /*__LAYER2_NR_MAC_PROTO_H__*/