Merge remote-tracking branch 'origin/fix-longrach-reg' into integration_2025_w12 (!3323)

Fix long RACH regression

Add some missing functionality that was not merged in !3088.

openair2/LAYER2/NR_MAC_UE/nr_ra_procedures.c

@@ -498,7 +498,7 @@ static void configure_prach_occasions(NR_UE_MAC_INST_t *mac, int scs)
           sl *= 2;
           // if only 1 slot per subframe (or 60kHz slot) in case of 30 or 120kHz it's the odd one
           // as defined in 5.3.2 of 211
-          if (prach_slots_in_sf == 1)
+          if (((prach_info.format & 0xff) > 3) && prach_slots_in_sf == 1)
             add_slot = 1;
         }
         int slot = sl + add_slot;
@@ -624,9 +624,12 @@ static void ra_preamble_msga_transmission(RA_config_t *ra, int scs)
 
   prach_resources->ra_preamble_rx_target_power = get_ra_preamble_rx_target_power(ra, scs);
 
-  ra->ra_rnti = nr_get_ra_rnti(ra->sched_ro_info.start_symbol, ra->sched_ro_info.slot, ra->sched_ro_info.fdm, 0);
+  // 3GPP TS 38.321 Section 5.1.3 says t_id for RA-RNTI depends on mu as specified in clause 5.3.2 in TS 38.211
+  // so mu = 0 for prach format < 4.
+  const int slot = ((ra->sched_ro_info.format & 0xff) < 4) ? ra->sched_ro_info.slot >> scs : ra->sched_ro_info.slot;
+  ra->ra_rnti = nr_get_ra_rnti(ra->sched_ro_info.start_symbol, slot, ra->sched_ro_info.fdm, 0);
   if (ra->ra_type == RA_2_STEP)
-    ra->MsgB_rnti = nr_get_MsgB_rnti(ra->sched_ro_info.start_symbol, ra->sched_ro_info.slot, ra->sched_ro_info.fdm, 0);
+    ra->MsgB_rnti = nr_get_MsgB_rnti(ra->sched_ro_info.start_symbol, slot, ra->sched_ro_info.fdm, 0);
 }
 
 // 38.321 Section 5.1.2 Random Access Resource selection