increase mcs ul upper bound to 24 when ue is cat4 and enb supports 64qam. Simplified max_mcs computation

lib/include/srslte/interfaces/sched_interface.h

@@ -146,9 +146,10 @@ public:
     std::vector<cc_cfg_t>               supported_cc_list; ///< list of UE supported CCs. First index for PCell
     ant_info_ded_t                      dl_ant_info;
     bool                                use_tbs_index_alt = false;
-    bool                                support_ul_64qam  = false;
     uint32_t                            measgap_period    = 0;
     uint32_t                            measgap_offset    = 0;
+    enum class ul64qam_cap { undefined, disabled, enabled };
+    ul64qam_cap support_ul64qam = ul64qam_cap::undefined;
   };
 
   typedef struct {

srsenb/hdr/stack/mac/sched_ue.h

@@ -73,7 +73,7 @@ struct cc_sched_ue {
   uint32_t ul_cqi_tti = 0;
   bool     dl_cqi_rx  = false;
 
-  uint32_t max_mcs_dl = 28, max_mcs_dl_alt = 27, max_mcs_ul = 28;
+  uint32_t max_mcs_dl = 28, max_mcs_ul = 28;
   uint32_t max_aggr_level = 3;
   int      fixed_mcs_ul = 0, fixed_mcs_dl = 0;
 

srsenb/src/stack/mac/sched_ue.cc

@@ -1201,17 +1201,17 @@ int sched_ue::enb_to_ue_cc_idx(uint32_t enb_cc_idx) const
 
 int cc_sched_ue::cqi_to_tbs(uint32_t nof_prb, uint32_t nof_re, bool use_tbs_index_alt, bool is_ul, uint32_t* mcs)
 {
+  using ul64qam_cap = sched_interface::ue_cfg_t::ul64qam_cap;
   uint32_t cqi, max_mcs, max_Qm;
   float    max_coderate;
   if (is_ul) {
     cqi          = ul_cqi;
-    // if cell supports UL 64QAM but the UE does not support it, cap the mcs to avoid Qm == 6
-    max_mcs = (not cfg->support_ul_64qam and cell_params->cfg.enable_64qam) ? std::min(max_mcs_ul, 20u) : max_mcs_ul;
-    max_Qm  = cfg->support_ul_64qam ? 6 : 4;
+    max_mcs      = max_mcs_ul;
+    max_Qm       = cfg->support_ul64qam == ul64qam_cap::enabled ? 6 : 4;
     max_coderate = srslte_cqi_to_coderate(std::min(cqi + 1u, 15u), false);
   } else {
     cqi          = dl_cqi;
-    max_mcs      = cfg->use_tbs_index_alt ? max_mcs_dl_alt : max_mcs_dl;
+    max_mcs      = max_mcs_dl;
     max_Qm       = use_tbs_index_alt ? 8 : 6;
     max_coderate = srslte_cqi_to_coderate(std::min(cqi + 1u, 15u), use_tbs_index_alt);
   }
@@ -1262,11 +1262,6 @@ cc_sched_ue::cc_sched_ue(const sched_interface::ue_cfg_t& cfg_,
   dl_cqi    = (ue_cc_idx == 0) ? cell_params->cfg.initial_dl_cqi : 0;
   set_cfg(cfg_);
 
-  // set max mcs
-  max_mcs_ul = cell_params->sched_cfg->pusch_max_mcs >= 0 ? cell_params->sched_cfg->pusch_max_mcs : 28;
-  max_mcs_dl = cell_params->sched_cfg->pdsch_max_mcs >= 0 ? cell_params->sched_cfg->pdsch_max_mcs : 28;
-  max_mcs_dl_alt =
-      cell_params->sched_cfg->pdsch_max_mcs >= 0 ? SRSLTE_MIN(cell_params->sched_cfg->pdsch_max_mcs, 27) : 27;
   max_aggr_level = cell_params->sched_cfg->max_aggr_level >= 0 ? cell_params->sched_cfg->max_aggr_level : 3;
 
   // set fixed mcs
@@ -1299,6 +1294,17 @@ void cc_sched_ue::set_cfg(const sched_interface::ue_cfg_t& cfg_)
   cfg     = &cfg_;
   cfg_tti = last_tti;
 
+  // set max mcs
+  max_mcs_ul = cell_params->sched_cfg->pusch_max_mcs >= 0 ? cell_params->sched_cfg->pusch_max_mcs : 28u;
+  if (cell_params->cfg.enable_64qam) {
+    const uint32_t max_64qam_mcs[] = {20, 24, 28};
+    max_mcs_ul                     = std::min(max_mcs_ul, max_64qam_mcs[(size_t)cfg->support_ul64qam]);
+  }
+  max_mcs_dl = cell_params->sched_cfg->pdsch_max_mcs >= 0 ? std::min(cell_params->sched_cfg->pdsch_max_mcs, 28) : 28u;
+  if (cfg->use_tbs_index_alt) {
+    max_mcs_dl = std::min(max_mcs_dl, 27u);
+  }
+
   if (ue_cc_idx == 0) {
     // PCell is always active
     cc_state_ = cc_st::active;

srsenb/src/stack/rrc/mac_controller.cc

@@ -499,8 +499,11 @@ void ue_cfg_apply_conn_reconf(ue_cfg_t& ue_cfg, const rrc_conn_recfg_r8_ies_s& c
 
 void ue_cfg_apply_capabilities(ue_cfg_t& ue_cfg, const rrc_cfg_t& rrc_cfg, const srslte::rrc_ue_capabilities_t& uecaps)
 {
-  ue_cfg.support_ul_64qam =
-      uecaps.support_ul_64qam and rrc_cfg.sibs[1].sib2().rr_cfg_common.pusch_cfg_common.pusch_cfg_basic.enable64_qam;
+  bool enb_enable64qam   = rrc_cfg.sibs[1].sib2().rr_cfg_common.pusch_cfg_common.pusch_cfg_basic.enable64_qam;
+  ue_cfg.support_ul64qam = ue_cfg_t::ul64qam_cap::undefined;
+  if (enb_enable64qam) {
+    ue_cfg.support_ul64qam = uecaps.support_ul_64qam ? ue_cfg_t::ul64qam_cap::enabled : ue_cfg_t::ul64qam_cap::disabled;
+  }
 }
 
 } // namespace srsenb