sched,feature: Enable configuring maximum coderate for SIB allocations

lib/include/srsran/interfaces/sched_interface.h

@@ -65,6 +65,7 @@ public:
     float       ul_snr_avg_alpha        = 0.05;
     int         init_ul_snr_value       = 5;
     int         init_dl_cqi             = 5;
+    float       max_sib_coderate        = 0.8;
   };
 
   struct cell_cfg_t {

srsenb/enb.conf.example

@@ -177,6 +177,7 @@ enable = false
 # ul_snr_avg_alpha:  Exponential Average alpha coefficient used in estimation of UL SNR
 # init_ul_snr_value: Initial UL SNR value used for computing MCS in the first UL grant
 # init_dl_cqi:       DL CQI value used before any CQI report is available to the eNB
+# max_sib_coderate:  Upper bound on SIB and RAR grants coderate
 #
 #####################################################################
 [scheduler]
@@ -200,6 +201,7 @@ enable = false
 #ul_snr_avg_alpha=0.05
 #init_ul_snr_value=5
 #init_dl_cqi=5
+#max_sib_coderate=0.8
 
 #####################################################################
 # eMBMS configuration options

srsenb/src/main.cc

@@ -159,6 +159,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("scheduler.ul_snr_avg_alpha", bpo::value<float>(&args->stack.mac.sched.ul_snr_avg_alpha)->default_value(0.05), "Exponential Average alpha coefficient used in estimation of UL SNR")
     ("scheduler.init_ul_snr_value", bpo::value<int>(&args->stack.mac.sched.init_ul_snr_value)->default_value(5), "Initial UL SNR value used for computing MCS in the first UL grant")
     ("scheduler.init_dl_cqi", bpo::value<int>(&args->stack.mac.sched.init_dl_cqi)->default_value(5), "DL CQI value used before any CQI report is available to the eNB")
+    ("scheduler.max_sib_coderate", bpo::value<float>(&args->stack.mac.sched.max_sib_coderate)->default_value(0.8), "Upper bound on SIB and RAR grants coderate")
 
 
     /* Downlink Channel emulator section */

srsenb/src/stack/mac/sched_phy_ch/sched_dci.cc

@@ -189,8 +189,8 @@ int generate_ra_bc_dci_format1a_common(srsran_dci_dl_t&           dci,
                                        const sched_cell_params_t& cell_params,
                                        uint32_t                   current_cfi)
 {
-  static const uint32_t Qm = 2, bc_rar_cqi = 4;
+  static const uint32_t Qm                = 2;
-  static const float    max_ctrl_coderate = std::min(srsran_cqi_to_coderate(bc_rar_cqi + 1, false), 0.932F * Qm);
+  static const float    max_ctrl_coderate = std::min(cell_params.sched_cfg->max_sib_coderate, 0.932F * Qm);
 
   // Calculate I_tbs for this TBS
   int tbs = static_cast<int>(req_bytes) * 8;