Allow to use multiple PUCCH at once

We are required to store multiple PUCCH (e.g., for multiple UEs).
However, nr_fill_pucch() automatically freed the previously active PUCCH
structure. Of course(!) this does not make sense.

However, the problem is that init_nr_transport() allocated only one
PUCCH structure. Also this does not make sense to me. The problem was
that slot_ahead was 0, which logically cannot happen in this function
(because slot_ahead is illogical, we must give the radio some time). The
reason is that it uses if_inst->sl_ahead, which, prior to this commit,
was not set.

The init_nr_transport() function is called normally from main() through
init_eNB_afterRU(). In this case, we initialize if_inst->sl_ahead to
what is set in main(). In the PNF case, however, we call
init_nr_transport() from the PNF thread, when receiving the start
request. In the main(), we wait for this to happen, before setting
if_inst->sl_ahead. Hence, initializing this variable (which we should
safely be able to do) before solves the problem.

executables/nr-softmodem.c

@@ -744,6 +744,9 @@ int main( int argc, char **argv ) {
   nvIPC_Init();
 #endif
 
+  for (int idx = 0; idx < RC.nb_nr_L1_inst; idx++)
+    RC.gNB[idx]->if_inst->sl_ahead = sl_ahead;
+
   if (NFAPI_MODE==NFAPI_MODE_PNF) {
     wait_nfapi_init("main?");
   }
@@ -756,7 +759,6 @@ int main( int argc, char **argv ) {
     // once all RUs are ready initialize the rest of the gNBs ((dependence on final RU parameters after configuration)
     printf("ALL RUs ready - init gNBs\n");
 
-    for (int idx=0;idx<RC.nb_nr_L1_inst;idx++) RC.gNB[idx]->if_inst->sl_ahead = sl_ahead;
     if(IS_SOFTMODEM_DOSCOPE) {
       sleep(1);
       scopeParms_t p;

openair1/PHY/INIT/nr_init.c

@@ -639,6 +639,7 @@ void init_nr_transport(PHY_VARS_gNB *gNB)
 
   int buffer_ul_slots; // the UL channels are scheduled sl_ahead before they are transmitted
   int slot_ahead = gNB->if_inst ? gNB->if_inst->sl_ahead : 6;
+  DevAssert(slot_ahead > 0);
   if (slot_ahead > nb_slots_per_period)
     buffer_ul_slots = nb_ul_slots_period + (slot_ahead - nb_slots_per_period);
   else

openair1/PHY/NR_TRANSPORT/pucch_rx.c

@@ -60,10 +60,6 @@ void nr_fill_pucch(PHY_VARS_gNB *gNB,
                    int slot,
                    nfapi_nr_pucch_pdu_t *pucch_pdu)
 {
-
-  if (NFAPI_MODE == NFAPI_MODE_PNF)
-    gNB->pucch[0].active = 0; // check if ture in monolithic mode
-
   bool found = false;
   for (int i = 0; i < gNB->max_nb_pucch; i++) {
     NR_gNB_PUCCH_t *pucch = &gNB->pucch[i];