use alternative method for conres CE scheduling

srsenb/src/stack/mac/mac.cc

@@ -260,6 +260,9 @@ int mac::ue_set_crnti(uint16_t temp_crnti, uint16_t crnti, sched_interface::ue_c
   if (temp_crnti != crnti) {
     // if C-RNTI is changed, it corresponds to older user. Handover scenario.
     ue_db[crnti]->reset();
+  } else {
+    // Schedule ConRes Msg4
+    scheduler.dl_mac_buffer_state(crnti, (uint32_t)srslte::dl_sch_lcid::CON_RES_ID);
   }
   int ret = ue_cfg(crnti, cfg);
   if (ret != SRSLTE_SUCCESS) {
@@ -513,6 +516,7 @@ void mac::rach_detected(uint32_t tti, uint32_t enb_cc_idx, uint32_t preamble_idx
     ue_cfg.supported_cc_list.emplace_back();
     ue_cfg.supported_cc_list.back().active     = true;
     ue_cfg.supported_cc_list.back().enb_cc_idx = enb_cc_idx;
+    ue_cfg.ue_bearers[0].direction             = srsenb::sched_interface::ue_bearer_cfg_t::BOTH;
     ue_cfg.dl_cfg.tm                           = SRSLTE_TM1;
     if (scheduler.ue_cfg(rnti, ue_cfg) != SRSLTE_SUCCESS) {
       Error("Registering new user rnti=0x%x to SCHED\n", rnti);
@@ -531,9 +535,6 @@ void mac::rach_detected(uint32_t tti, uint32_t enb_cc_idx, uint32_t preamble_idx
     // Trigger scheduler RACH
     scheduler.dl_rach_info(enb_cc_idx, rar_info);
 
-    // Schedule ConRes Msg4
-    scheduler.dl_mac_buffer_state(rnti, (uint32_t)srslte::dl_sch_lcid::CON_RES_ID);
-
     log_h->info("RACH:  tti=%d, preamble=%d, offset=%d, temp_crnti=0x%x\n", tti, preamble_idx, time_adv, rnti);
     log_h->console("RACH:  tti=%d, preamble=%d, offset=%d, temp_crnti=0x%x\n", tti, preamble_idx, time_adv, rnti);
   });

srsenb/src/stack/mac/scheduler_ue.cc

@@ -879,6 +879,7 @@ std::pair<uint32_t, uint32_t> sched_ue::get_requested_dl_bytes(uint32_t ue_cc_id
   // Ensure there is space for ConRes and RRC Setup
   // SRB0 is a special case due to being RLC TM (no segmentation possible)
   if (not bearer_is_dl(&lch[0])) {
+    log_h->error("SRB0 must always be activated for DL\n");
     return {0, 0};
   }
   if (not carriers[ue_cc_idx].is_active()) {
@@ -894,7 +895,11 @@ std::pair<uint32_t, uint32_t> sched_ue::get_requested_dl_bytes(uint32_t ue_cc_id
   }
   // Add pending CEs
   if (ue_cc_idx == 0) {
-    for (const auto& ce : pending_ces) {
+    if (srb0_data == 0 and not pending_ces.empty() and pending_ces.front() == srslte::dl_sch_lcid::CON_RES_ID) {
+      // Wait for SRB0 data to be available for Msg4 before scheduling the ConRes CE
+      return {0, 0};
+    }
+    for (const ce_cmd& ce : pending_ces) {
       sum_ce_data += srslte::ce_total_size(ce);
     }
   }

srsenb/src/stack/rrc/rrc_ue.cc

@@ -243,6 +243,7 @@ void rrc::ue::handle_rrc_con_req(rrc_conn_request_s* msg)
 {
   if (not parent->s1ap->is_mme_connected()) {
     parent->rrc_log->error("MME isn't connected. Sending Connection Reject\n");
+    parent->mac->ue_set_crnti(rnti, rnti, &current_sched_ue_cfg);
     send_connection_reject();
     return;
   }
@@ -328,11 +329,6 @@ void rrc::ue::handle_rrc_con_setup_complete(rrc_conn_setup_complete_s* msg, srsl
 
 void rrc::ue::send_connection_reject()
 {
-  // Activate SRB0 if not yet activated
-  sched_interface::ue_bearer_cfg_t srb0{};
-  srb0.direction = sched_interface::ue_bearer_cfg_t::DL;
-  parent->mac->bearer_ue_cfg(rnti, 0, &srb0);
-
   dl_ccch_msg_s dl_ccch_msg;
   dl_ccch_msg.msg.set_c1().set_rrc_conn_reject().crit_exts.set_c1().set_rrc_conn_reject_r8().wait_time = 10;
   send_dl_ccch(&dl_ccch_msg);