Make MBMS MCS configurable for the eNB.

srsenb/enb.conf.example

@@ -165,12 +165,14 @@ pusch_max_mcs    = 16
 # enable:               Enable MBMS transmission in the eNB
 # m1u_multiaddr:        Multicast addres the M1-U socket will register to
 # m1u_if_addr:          Address of the inteferface the M1-U interface will listen for multicast packets.
+# mcs:                  Modulation and Coding scheme for MBMS traffic.
 #
 #####################################################################
 [embms]
 #enable = false
 #m1u_multiaddr = 239.255.0.1
 #m1u_if_addr = 127.0.1.201
+#mcs = 20
 
 
 

srsenb/hdr/stack/enb_stack_base.h

@@ -35,6 +35,7 @@ typedef struct {
   bool        enable;
   std::string m1u_multiaddr;
   std::string m1u_if_addr;
+  uint16_t    mcs;
 } embms_args_t;
 
 typedef struct {

srsenb/hdr/stack/rrc/rrc_config.h

@@ -73,6 +73,7 @@ struct rrc_cfg_t {
   rrc_cfg_cqi_t                       cqi_cfg;
   rrc_cfg_qci_t                       qci_cfg[MAX_NOF_QCI];
   bool                                enable_mbsfn;
+  uint16_t                            mbms_mcs;
   uint32_t                            inactivity_timeout_ms;
   srslte::CIPHERING_ALGORITHM_ID_ENUM eea_preference_list[srslte::CIPHERING_ALGORITHM_ID_N_ITEMS];
   srslte::INTEGRITY_ALGORITHM_ID_ENUM eia_preference_list[srslte::INTEGRITY_ALGORITHM_ID_N_ITEMS];

srsenb/src/enb_cfg_parser.cc

@@ -955,6 +955,7 @@ int set_derived_args(all_args_t* args_, rrc_cfg_t* rrc_cfg_, phy_cfg_t* phy_cfg_
 
   rrc_cfg_->inactivity_timeout_ms = args_->general.rrc_inactivity_timer;
   rrc_cfg_->enable_mbsfn          = args_->stack.embms.enable;
+  rrc_cfg_->mbms_mcs              = args_->stack.embms.mcs;
 
   // Check number of control symbols
   if (args_->stack.mac.sched.min_nof_ctrl_symbols > args_->stack.mac.sched.max_nof_ctrl_symbols) {

srsenb/src/main.cc

@@ -195,6 +195,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("embms.enable", bpo::value<bool>(&args->stack.embms.enable)->default_value(false), "Enables MBMS in the eNB")
     ("embms.m1u_multiaddr", bpo::value<string>(&args->stack.embms.m1u_multiaddr)->default_value("239.255.0.1"), "M1-U Multicast address the eNB joins.")
     ("embms.m1u_if_addr", bpo::value<string>(&args->stack.embms.m1u_if_addr)->default_value("127.0.1.201"), "IP address of the interface the eNB will listen for M1-U traffic.")
+    ("embms.mcs", bpo::value<uint16_t>(&args->stack.embms.mcs)->default_value(20), "Modulation and Coding scheme of MBMS traffic.")
     ;
 
   // Positional options - config file location
@@ -276,7 +277,7 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     }
   }
 
-  // Covert eNB Id
+  // Convert eNB Id
   std::size_t pos = {};
   try {
     args->enb.enb_id = std::stoi(enb_id, &pos, 0);

srsenb/src/stack/rrc/rrc.cc

@@ -790,7 +790,15 @@ void rrc::configure_mbsfn_sibs(sib_type2_s* sib2_, sib_type13_r9_s* sib13_)
            &byte[0],
            3); // TODO: Check if service is set to 1
   }
-  pmch_item->pmch_cfg_r9.data_mcs_r9         = 20;
+
+  uint16_t mbms_mcs = cfg.mbms_mcs;
+  if (mbms_mcs > 28){
+    mbms_mcs = 28; // TS 36.213, Table 8.6.1-1
+    rrc_log->warning("PMCH data MCS too high, setting it to 28\n");
+  }
+
+  rrc_log->debug("PMCH data MCS=%d\n", mbms_mcs);
+  pmch_item->pmch_cfg_r9.data_mcs_r9         = mbms_mcs;
   pmch_item->pmch_cfg_r9.mch_sched_period_r9 = pmch_cfg_r9_s::mch_sched_period_r9_e_::rf64;
   pmch_item->pmch_cfg_r9.sf_alloc_end_r9     = 64 * 6;