rlc v2: change time keeping

RLC has timers. We need to keep track of time. We chose to not use
realtime but 'processing time'. That is we send a tick to RLC for every
subframe when it is processed by the softmodem. Before this commit we
used to increase time in the function mac_rlc_status_ind which may not be
called every subframe (especially in TDD mode). So we need another way
to keep track of time.

We introduce rlc_tick() and call it in eNB_dlsch_ulsch_scheduler, which
is called every subframe, both in FDD and TDD.

We also call rlc_tick() in the function ru_thread_synch() because
pdcp_run() and rrc_rx_tx() are called there too.

It may not be the best solution. To be revised if needed.

Note: the UE has not been touched. Some modification is needed for the UE
too, most probably.

openair2/LAYER2/MAC/eNB_scheduler.c

@@ -914,7 +914,9 @@ eNB_dlsch_ulsch_scheduler(module_id_t module_idP,
 
 #if (!defined(PRE_SCD_THREAD))
   if (!NODE_IS_DU(RC.rrc[module_idP]->node_type)) {
+    void rlc_tick(int, int);
     PROTOCOL_CTXT_SET_BY_MODULE_ID(&ctxt, module_idP, ENB_FLAG_YES, NOT_A_RNTI, frameP, subframeP, module_idP);
+    rlc_tick(frameP, subframeP);
     pdcp_run(&ctxt);
     pdcp_mbms_run(&ctxt);
     rrc_rx_tx(&ctxt, CC_id);

openair2/LAYER2/rlc_v2/rlc_oai_api.c

@@ -177,14 +177,6 @@ mac_rlc_status_resp_t mac_rlc_status_ind(
   mac_rlc_status_resp_t ret;
   rlc_entity_t *rb;
 
-  /* TODO: handle time a bit more properly */
-  if (rlc_current_time_last_frame != frameP ||
-      rlc_current_time_last_subframe != subframeP) {
-    rlc_current_time++;
-    rlc_current_time_last_frame = frameP;
-    rlc_current_time_last_subframe = subframeP;
-  }
-
   rlc_manager_lock(rlc_ue_manager);
   ue = rlc_manager_get_ue(rlc_ue_manager, rntiP);
 
@@ -1028,3 +1020,27 @@ rlc_op_status_t rrc_rlc_remove_ue (const protocol_ctxt_t* const x)
 
   return RLC_OP_STATUS_OK;
 }
+
+void rlc_tick(int frame, int subframe)
+{
+  int expected_next_frame;
+  int expected_next_subframe;
+
+  if (frame != rlc_current_time_last_frame ||
+      subframe != rlc_current_time_last_subframe) {
+    /* warn if discontinuity in ticks */
+    expected_next_subframe = (rlc_current_time_last_subframe + 1) % 10;
+    if (expected_next_subframe == 0)
+      expected_next_frame = (rlc_current_time_last_frame + 1) % 1024;
+    else
+      expected_next_frame = rlc_current_time_last_frame;
+    if (expected_next_frame != frame || expected_next_subframe != subframe)
+      LOG_W(RLC, "rlc_tick: discontinuity (expected %d.%d, got %d.%d)\n",
+            expected_next_frame, expected_next_subframe,
+            frame, subframe);
+
+    rlc_current_time++;
+    rlc_current_time_last_frame = frame;
+    rlc_current_time_last_subframe = subframe;
+  }
+}

targets/RT/USER/lte-ru.c

@@ -2017,6 +2017,7 @@ void *ru_thread_synch(void *arg) {
 
 #if defined(PRE_SCD_THREAD)
 void *pre_scd_thread( void *param ) {
+  void rlc_tick(int, int);
   static int              eNB_pre_scd_status;
   protocol_ctxt_t         ctxt;
   int                     frame;
@@ -2051,6 +2052,7 @@ void *pre_scd_thread( void *param ) {
     AssertFatal((ret=pthread_mutex_unlock(&ru->proc.mutex_pre_scd))==0,"mutex_unlock returns %d\n",ret);
     PROTOCOL_CTXT_SET_BY_MODULE_ID(&ctxt, Mod_id, ENB_FLAG_YES,
                                    NOT_A_RNTI, frame, subframe,Mod_id);
+    rlc_tick(frame, subframe);
     pdcp_run(&ctxt);
 
     for (CC_id = 0; CC_id < MAX_NUM_CCs; CC_id++) {