sched,lte: separated adaptive mcs learning rate argument into two arguments, one for DL and the other for UL

srsenb/enb.conf.example

@@ -178,7 +178,8 @@ enable = false
 # target_bler:       Target BLER (in decimal) to achieve via adaptive link
 # max_delta_dl_cqi:  Maximum shift in CQI for adaptive DL link
 # max_delta_ul_snr:  Maximum shift in UL SNR for adaptive UL link
-# adaptive_link_step_size: Step size or learning rate used in adaptive link
+# adaptive_dl_mcs_step_size: Step size or learning rate used in adaptive DL MCS link
+# adaptive_ul_mcs_step_size: Step size or learning rate used in adaptive UL MCS link
 # min_tpc_tti_interval: Minimum TTI interval between TPCs different than 1
 # 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
@@ -204,7 +205,8 @@ enable = false
 #target_bler = 0.05
 #max_delta_dl_cqi = 5
 #max_delta_ul_snr = 5
-#adaptive_link_step_size = 0.001
+#adaptive_dl_mcs_step_size = 0.001
+#adaptive_ul_mcs_step_size = 0.001
 #min_tpc_tti_interval = 1
 #ul_snr_avg_alpha=0.05
 #init_ul_snr_value=5

srsenb/hdr/stack/mac/sched_interface.h

@@ -62,7 +62,8 @@ public:
     float       target_bler             = 0.05;
     float       max_delta_dl_cqi        = 5;
     float       max_delta_ul_snr        = 5;
-    float       adaptive_link_step_size = 0.001;
+    float       adaptive_dl_mcs_step_size = 0.001;
+    float       adaptive_ul_mcs_step_size = 0.001;
     uint32_t    min_tpc_tti_interval    = 1;
     float       ul_snr_avg_alpha        = 0.05;
     int         init_ul_snr_value       = 5;

srsenb/hdr/stack/mac/sched_ue_ctrl/sched_ue_cell.h

@@ -94,7 +94,8 @@ private:
   cc_st     cc_state_ = cc_st::idle;
 
   // CQI
-  float delta_inc = 0, delta_dec = 0;
+  float ul_delta_inc = 0, ul_delta_dec = 0;
+  float dl_delta_inc = 0, dl_delta_dec = 0;
   float dl_cqi_coeff = 0, ul_snr_coeff = 0;
   float max_cqi_coeff = -5, max_snr_coeff = 5;
 

srsenb/src/main.cc

@@ -156,7 +156,8 @@ void parse_args(all_args_t* args, int argc, char* argv[])
     ("scheduler.target_bler", bpo::value<float>(&args->stack.mac.sched.target_bler)->default_value(0.05), "Target BLER (in decimal) to achieve via adaptive link")
     ("scheduler.max_delta_dl_cqi", bpo::value<float>(&args->stack.mac.sched.max_delta_dl_cqi)->default_value(5.0), "Maximum shift in CQI for adaptive DL link")
     ("scheduler.max_delta_ul_snr", bpo::value<float>(&args->stack.mac.sched.max_delta_ul_snr)->default_value(5.0), "Maximum shift in UL SNR for adaptive UL link")
-    ("scheduler.adaptive_link_step_size", bpo::value<float>(&args->stack.mac.sched.adaptive_link_step_size)->default_value(0.001), "Step size or learning rate used in adaptive link")
+    ("scheduler.adaptive_dl_mcs_step_size", bpo::value<float>(&args->stack.mac.sched.adaptive_dl_mcs_step_size)->default_value(0.001), "Step size or learning rate used in adaptive DL MCS link")
+    ("scheduler.adaptive_ul_mcs_step_size", bpo::value<float>(&args->stack.mac.sched.adaptive_ul_mcs_step_size)->default_value(0.001), "Step size or learning rate used in adaptive UL MCS link")
     ("scheduler.min_tpc_tti_interval", bpo::value<uint32_t>(&args->stack.mac.sched.min_tpc_tti_interval)->default_value(1), "Minimum TTI interval between positive or negative TPCs")
     ("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")

srsenb/src/stack/mac/sched_ue_ctrl/sched_ue_cell.cc

@@ -51,8 +51,10 @@ sched_ue_cell::sched_ue_cell(uint16_t rnti_, const sched_cell_params_t& cell_cfg
   dl_cqi_ctxt(cell_cfg_.nof_prb(), 0, cell_cfg_.sched_cfg->init_dl_cqi)
 {
   float target_bler = cell_cfg->sched_cfg->target_bler;
-  delta_inc         = cell_cfg->sched_cfg->adaptive_link_step_size; // delta_{down} of OLLA
-  delta_dec         = (1 - target_bler) * delta_inc / target_bler;
+  dl_delta_inc      = cell_cfg->sched_cfg->adaptive_dl_mcs_step_size; // delta_{down} of OLLA
+  dl_delta_dec      = (1 - target_bler) * dl_delta_inc / target_bler;
+  ul_delta_inc      = cell_cfg->sched_cfg->adaptive_ul_mcs_step_size; // delta_{down} of OLLA
+  ul_delta_dec      = (1 - target_bler) * ul_delta_inc / target_bler;
   max_cqi_coeff     = cell_cfg->sched_cfg->max_delta_dl_cqi;
   max_snr_coeff     = cell_cfg->sched_cfg->max_delta_ul_snr;
 }
@@ -202,8 +204,8 @@ int sched_ue_cell::set_ul_crc(tti_point tti_rx, bool crc_res)
     if (ul_harq != nullptr) {
       int mcs = ul_harq->get_mcs(0);
       // Note: Avoid keeping increasing the snr delta offset, if MCS is already is at its limit
-      float delta_dec_eff = mcs <= 0 ? 0 : delta_dec;
-      float delta_inc_eff = mcs >= (int)max_mcs_ul ? 0 : delta_inc;
+      float delta_dec_eff = mcs <= 0 ? 0 : ul_delta_dec;
+      float delta_inc_eff = mcs >= (int)max_mcs_ul ? 0 : ul_delta_inc;
       ul_snr_coeff += crc_res ? delta_inc_eff : -delta_dec_eff;
       ul_snr_coeff = std::min(std::max(-max_snr_coeff, ul_snr_coeff), max_snr_coeff);
       logger.info("SCHED: UL adaptive link: rnti=0x%x, snr_estim=%.2f, last_mcs=%d, snr_offset=%f",
@@ -239,8 +241,8 @@ int sched_ue_cell::set_ack_info(tti_point tti_rx, uint32_t tb_idx, bool ack)
   if (cell_cfg->sched_cfg->target_bler > 0 and fixed_mcs_dl < 0) {
     int mcs = std::get<2>(p2);
     // Note: Avoid keeping increasing the snr delta offset, if MCS is already is at its limit
-    float delta_dec_eff = mcs <= 0 ? 0 : delta_dec;
-    float delta_inc_eff = mcs >= (int)max_mcs_dl ? 0 : delta_inc;
+    float delta_dec_eff = mcs <= 0 ? 0 : dl_delta_dec;
+    float delta_inc_eff = mcs >= (int)max_mcs_dl ? 0 : dl_delta_inc;
     dl_cqi_coeff += ack ? delta_inc_eff : -delta_dec_eff;
     dl_cqi_coeff = std::min(std::max(-max_cqi_coeff, dl_cqi_coeff), max_cqi_coeff);
     logger.info("SCHED: DL adaptive link: rnti=0x%x, cqi=%d, last_mcs=%d, cqi_offset=%f",