added parameter to limit the maxMIMO-layers on DL (i.e. to 2 for 4x4)

openair2/GNB_APP/gnb_config.c

@@ -718,6 +718,7 @@ void RCconfig_verify(configmodule_interface_t *cfg, ngran_node_t node_type)
     verify_gnb_param_notset(gnbp, GNB_DO_CSIRS_IDX, GNB_CONFIG_STRING_DOCSIRS);
     verify_gnb_param_notset(gnbp, GNB_DO_SRS_IDX, GNB_CONFIG_STRING_DOSRS);
     verify_gnb_param_notset(gnbp, GNB_FORCE256QAMOFF_IDX, GNB_CONFIG_STRING_FORCE256QAMOFF);
+    verify_gnb_param_notset(gnbp, GNB_MAXMIMOLAYERS_IDX, GNB_CONFIG_STRING_MAXMIMOLAYERS);
 
     // check for some general sections
     verify_section_notset(cfg, NULL, CONFIG_STRING_L1_LIST);
@@ -1304,12 +1305,14 @@ void RCconfig_nr_macrlc(configmodule_interface_t *cfg)
   config.force_256qam_off = *GNBParamList.paramarray[0][GNB_FORCE256QAMOFF_IDX].iptr;
   config.force_UL256qam_off = *GNBParamList.paramarray[0][GNB_FORCEUL256QAMOFF_IDX].iptr;
   config.use_deltaMCS = *GNBParamList.paramarray[0][GNB_USE_DELTA_MCS_IDX].iptr != 0;
+  config.maxMIMO_layers = *GNBParamList.paramarray[0][GNB_MAXMIMOLAYERS_IDX].iptr;
   LOG_I(GNB_APP,
-        "CSI-RS %d, SRS %d, 256 QAM %s, delta_MCS %s\n",
+        "CSI-RS %d, SRS %d, 256 QAM %s, delta_MCS %s, maxMIMO_Layers %d\n",
         config.do_CSIRS,
         config.do_SRS,
         config.force_256qam_off ? "force off" : "may be on",
-        config.use_deltaMCS ? "on" : "off");
+        config.use_deltaMCS ? "on" : "off",
+        config.maxMIMO_layers);
 
   NR_ServingCellConfigCommon_t *scc = get_scc_config(cfg, config.minRXTXTIME);
   //xer_fprint(stdout, &asn_DEF_NR_ServingCellConfigCommon, scc);

openair2/GNB_APP/gnb_paramdef.h

@@ -125,6 +125,7 @@ typedef enum {
 #define GNB_CONFIG_STRING_ULPRBBLACKLIST                "ul_prbblacklist"
 #define GNB_CONFIG_STRING_UMONDEFAULTDRB                "um_on_default_drb"
 #define GNB_CONFIG_STRING_FORCE256QAMOFF                "force_256qam_off"
+#define GNB_CONFIG_STRING_MAXMIMOLAYERS                 "maxMIMO_layers"
 #define GNB_CONFIG_STRING_ENABLE_SDAP                   "enable_sdap"
 #define GNB_CONFIG_STRING_DRBS                          "drbs"
 #define GNB_CONFIG_STRING_USE_DELTA_MCS                 "use_deltaMCS"
@@ -136,6 +137,7 @@ typedef enum {
 
 #define GNB_CONFIG_HLP_STRING_ENABLE_SDAP               "enable the SDAP layer\n"
 #define GNB_CONFIG_HLP_FORCE256QAMOFF                   "suppress activation of 256 QAM despite UE support"
+#define GNB_CONFIG_HLP_MAXMIMOLAYERS                    "limit on maxMIMO-layers for DL"
 #define GNB_CONFIG_HLP_STRING_DRBS                      "Number of total DRBs to establish, including the mandatory for PDU SEssion (default=1)\n"
 #define GNB_CONFIG_HLP_GNB_DU_ID "defines the gNB-DU ID (only applicable for DU)"
 #define GNB_CONFIG_HLP_GNB_CU_UP_ID "defines the gNB-CU-UP ID (only applicable for CU-UP)"
@@ -177,6 +179,7 @@ typedef enum {
 {GNB_CONFIG_STRING_GNB_CU_UP_ID, GNB_CONFIG_HLP_GNB_CU_UP_ID, 0,      .u64ptr=NULL, .defint64val=1,               TYPE_UINT64,    0},  \
 {GNB_CONFIG_STRING_USE_DELTA_MCS, GNB_CONFIG_HLP_USE_DELTA_MCS,     0,            .iptr=NULL,  .defintval=0,                 TYPE_INT,       0},  \
 {GNB_CONFIG_STRING_FORCEUL256QAMOFF, GNB_CONFIG_HLP_FORCEUL256QAMOFF,     0,            .iptr=NULL,  .defintval=0,                 TYPE_INT,       0},  \
+{GNB_CONFIG_STRING_MAXMIMOLAYERS, GNB_CONFIG_HLP_MAXMIMOLAYERS, 0,      .iptr=NULL, .defintval=-1,               TYPE_INT,    0},  \
 }
 // clang-format on
 
@@ -212,6 +215,7 @@ typedef enum {
 #define GNB_GNB_CU_UP_ID_IDX            28
 #define GNB_USE_DELTA_MCS_IDX           29
 #define GNB_FORCEUL256QAMOFF_IDX        30
+#define GNB_MAXMIMOLAYERS_IDX           31
 
 #define TRACKING_AREA_CODE_OKRANGE {0x0001,0xFFFD}
 #define GNBPARAMS_CHECK {                                         \

openair2/LAYER2/NR_MAC_gNB/nr_mac_gNB.h

@@ -138,6 +138,7 @@ typedef struct nr_mac_config_t {
   bool force_256qam_off;
   bool force_UL256qam_off;
   bool use_deltaMCS;
+  int maxMIMO_layers;
   //int pusch_TargetSNRx10;
   //int pucch_TargetSNRx10;
 } nr_mac_config_t;

openair2/RRC/NR/nr_rrc_config.c

@@ -512,7 +512,8 @@ static void config_csiim(int do_csirs,
 
 void set_dl_maxmimolayers(NR_PDSCH_ServingCellConfig_t *pdsch_servingcellconfig,
                           const NR_ServingCellConfigCommon_t *scc,
-                          const NR_UE_NR_Capability_t *uecap)
+                          const NR_UE_NR_Capability_t *uecap,
+			  int maxMIMO_layers)
 {
 
   if(!pdsch_servingcellconfig->ext1)
@@ -536,7 +537,10 @@ void set_dl_maxmimolayers(NR_PDSCH_ServingCellConfig_t *pdsch_servingcellconfig,
           supported_bw_comparison(bw_mhz, &dl_fs->supportedBandwidthDL, dl_fs->channelBW_90mhz) &&
           dl_fs->maxNumberMIMO_LayersPDSCH) {
         long ue_supported_layers = (2 << *dl_fs->maxNumberMIMO_LayersPDSCH);
+        if (maxMIMO_layers == -1) 
           *pdsch_servingcellconfig->ext1->maxMIMO_Layers = NR_MAX_SUPPORTED_DL_LAYERS < ue_supported_layers ? NR_MAX_SUPPORTED_DL_LAYERS : ue_supported_layers;
+        else 
+          *pdsch_servingcellconfig->ext1->maxMIMO_Layers = maxMIMO_layers < ue_supported_layers ? maxMIMO_layers : ue_supported_layers;
         return;
       }
     }
@@ -2397,7 +2401,7 @@ static NR_SpCellConfig_t *get_initial_SpCellConfig(int uid,
   pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH = calloc(1, sizeof(*pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH));
   *pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH = NR_PDSCH_ServingCellConfig__nrofHARQ_ProcessesForPDSCH_n16;
   pdsch_servingcellconfig->pucch_Cell = NULL;
-  set_dl_maxmimolayers(pdsch_servingcellconfig, scc, NULL);
+  set_dl_maxmimolayers(pdsch_servingcellconfig, scc, NULL, configuration->maxMIMO_layers);
 
   // Downlink BWPs
   int n_dl_bwp = 0;
@@ -2600,7 +2604,7 @@ void update_cellGroupConfig(NR_CellGroupConfig_t *cellGroupConfig,
   NR_SpCellConfig_t *SpCellConfig = cellGroupConfig->spCellConfig;
 
   NR_PDSCH_ServingCellConfig_t *pdsch_servingcellconfig = SpCellConfig->spCellConfigDedicated->pdsch_ServingCellConfig->choice.setup;
-  set_dl_maxmimolayers(pdsch_servingcellconfig, scc, uecap);
+  set_dl_maxmimolayers(pdsch_servingcellconfig, scc, uecap, configuration->maxMIMO_layers);
 
   NR_CSI_MeasConfig_t *csi_MeasConfig = SpCellConfig->spCellConfigDedicated->csi_MeasConfig->choice.setup;
   for (int report = 0; report < csi_MeasConfig->csi_ReportConfigToAddModList->list.count; report++) {
@@ -2979,7 +2983,7 @@ NR_CellGroupConfig_t *get_default_secondaryCellGroup(const NR_ServingCellConfigC
   pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH = calloc(1, sizeof(*pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH));
   *pdsch_servingcellconfig->nrofHARQ_ProcessesForPDSCH = NR_PDSCH_ServingCellConfig__nrofHARQ_ProcessesForPDSCH_n16;
   pdsch_servingcellconfig->pucch_Cell = NULL;
-  set_dl_maxmimolayers(pdsch_servingcellconfig, servingcellconfigcommon, uecap);
+  set_dl_maxmimolayers(pdsch_servingcellconfig, servingcellconfigcommon, uecap, configuration->maxMIMO_layers);
   pdsch_servingcellconfig->ext1->processingType2Enabled = NULL;
 
   secondaryCellGroup->spCellConfig->spCellConfigDedicated->csi_MeasConfig = NULL;