allow specification of subset of valid measurement gap offsets in rr.conf

lib/include/srsran/interfaces/enb_rrc_interface_types.h

@@ -42,6 +42,7 @@ struct rrc_meas_cfg_t {
   std::vector<asn1::rrc::report_cfg_eutra_s> meas_reports;
   asn1::rrc::quant_cfg_eutra_s               quant_cfg;
   uint32_t                                   meas_gap_period;
+  std::vector<uint32_t>                      meas_gap_offset_subframe;
   uint32_t                                   allowed_meas_bw;
 };
 

srsenb/hdr/stack/rrc/rrc_cell_cfg.h

@@ -73,10 +73,10 @@ public:
   const static uint32_t N_PUCCH_MAX_PRB = 4; // Maximum number of PRB to use for PUCCH ACK/NACK in CS mode
   const static uint32_t N_PUCCH_MAX_RES = 3 * SRSRAN_NRE * N_PUCCH_MAX_PRB;
 
-  uint32_t                          next_measgap_offset = 0;
-  pucch_idx_sched_t                 sr_sched            = {};
-  pucch_idx_sched_t                 cqi_sched           = {};
-  std::array<bool, N_PUCCH_MAX_RES> n_pucch_cs_used     = {};
+  pucch_idx_sched_t                 sr_sched           = {};
+  pucch_idx_sched_t                 cqi_sched          = {};
+  std::array<bool, N_PUCCH_MAX_RES> n_pucch_cs_used    = {};
+  std::array<uint32_t, 14>          meas_gap_alloc_map = {};
 };
 
 /** Storage of CQI/SR/PUCCH CS resources across multiple frequencies and for multiple users */

srsenb/rr.conf.example

@@ -62,6 +62,7 @@ cell_list =
     //ul_earfcn = 21400;
     ho_active = false;
     //meas_gap_period = 0; // 0 (inactive), 40 or 80
+    //meas_gap_offset_subframe = [6, 12, 18, 24, 30];
     // target_pusch_sinr = -1;
     // target_pucch_sinr = -1;
     // allowed_meas_bw = 6;

srsenb/src/enb_cfg_parser.cc

@@ -760,6 +760,14 @@ static int parse_cell_list(all_args_t* args, rrc_cfg_t* rrc_cfg, Setting& root)
         cell_cfg.root_seq_idx, cellroot, "root_seq_idx", rrc_cfg->sibs[1].sib2().rr_cfg_common.prach_cfg.root_seq_idx);
     parse_default_field(cell_cfg.initial_dl_cqi, cellroot, "initial_dl_cqi", 5u);
     parse_default_field(cell_cfg.meas_cfg.meas_gap_period, cellroot, "meas_gap_period", 0u);
+    if (cellroot.exists("meas_gap_offset_subframe")) {
+      cell_cfg.meas_cfg.meas_gap_offset_subframe.resize(cellroot["meas_gap_offset_subframe"].getLength());
+      for (uint32_t j = 0; j < (uint32_t)cellroot["meas_gap_offset_subframe"].getLength(); ++j) {
+        cell_cfg.meas_cfg.meas_gap_offset_subframe[j] = (uint32_t)cellroot["meas_gap_offset_subframe"][j];
+        srsran_assert(cell_cfg.meas_cfg.meas_gap_offset_subframe[j] < cell_cfg.meas_cfg.meas_gap_period,
+                      "meas gap offsets must be smaller than meas gap period");
+      }
+    }
     HANDLEPARSERCODE(parse_default_field(cell_cfg.target_pusch_sinr_db, cellroot, "target_pusch_sinr", -1));
     HANDLEPARSERCODE(parse_default_field(cell_cfg.target_pucch_sinr_db, cellroot, "target_pucch_sinr", -1));
     HANDLEPARSERCODE(parse_default_field(cell_cfg.enable_phr_handling, cellroot, "enable_phr_handling", false));

srsenb/src/stack/rrc/rrc_cell_cfg.cc

@@ -218,6 +218,7 @@ bool ue_cell_ded_list::rem_last_cell()
 
 bool ue_cell_ded_list::alloc_cell_resources(uint32_t ue_cc_idx)
 {
+  const uint32_t meas_gap_duration = 6;
   // Allocate CQI, SR, and PUCCH CS resources. If failure, do not add new cell
   if (ue_cc_idx == UE_PCELL_CC_IDX) {
     if (not alloc_sr_resources(cfg.sr_cfg.period)) {
@@ -226,9 +227,30 @@ bool ue_cell_ded_list::alloc_cell_resources(uint32_t ue_cc_idx)
     }
 
     ue_cell_ded* cell     = get_ue_cc_idx(UE_PCELL_CC_IDX);
+    cell->meas_gap_offset = 0;
     cell->meas_gap_period = cell->cell_common->cell_cfg.meas_cfg.meas_gap_period;
-    cell->meas_gap_offset = pucch_res->next_measgap_offset;
-    pucch_res->next_measgap_offset += 6;
+    if (cell->meas_gap_period > 0) {
+      if (not cell->cell_common->cell_cfg.meas_cfg.meas_gap_offset_subframe.empty()) {
+        // subframes specified
+        uint32_t min_users = std::numeric_limits<uint32_t>::max();
+        for (uint32_t i = 0; i < cell->cell_common->cell_cfg.meas_cfg.meas_gap_offset_subframe.size(); ++i) {
+          uint32_t idx_offset = cell->cell_common->cell_cfg.meas_cfg.meas_gap_offset_subframe[i] / meas_gap_duration;
+          if (pucch_res->meas_gap_alloc_map[idx_offset] < min_users) {
+            min_users             = pucch_res->meas_gap_alloc_map[idx_offset];
+            cell->meas_gap_offset = cell->cell_common->cell_cfg.meas_cfg.meas_gap_offset_subframe[i];
+          }
+        }
+      } else {
+        uint32_t min_users = std::numeric_limits<uint32_t>::max();
+        for (uint32_t meas_offset = 0; meas_offset < cell->cell_common->cell_cfg.meas_cfg.meas_gap_period;
+             meas_offset += meas_gap_duration) {
+          if (pucch_res->meas_gap_alloc_map[meas_offset / meas_gap_duration] < min_users) {
+            min_users             = pucch_res->meas_gap_alloc_map[meas_offset / meas_gap_duration];
+            cell->meas_gap_offset = meas_offset;
+          }
+        }
+      }
+    }
   } else {
     if (ue_cc_idx == 1 and not n_pucch_cs_present) {
       // Allocate resources for Format1b CS (will be optional PUCCH3/CS)