Force retx for mcs>29 and new tb if rv=0 && mcs<29

lib/include/srslte/common/common.h

@@ -52,7 +52,6 @@
 #define TTIMOD_SZ       (((2*HARQ_DELAY_MS) < 10)?10:20)
 #define TTIMOD(tti)     (tti%TTIMOD_SZ)
 
-#define MOD_N_PROC      (2*HARQ_DELAY_MS-8)
 #define ASYNC_DL_SCHED  (HARQ_DELAY_MS <= 4)
 
 // Cat 3 UE - Max number of DL-SCH transport block bits received within a TTI

srsue/hdr/mac/dl_harq.h

@@ -259,7 +259,7 @@ private:
         memcpy(&cur_grant, &grant, sizeof(Tgrant));
 
         // If data has not yet been successfully decoded
-        if (!ack) {
+        if (!ack || (grant.rv[tid]==0 && grant.phy_grant.dl.mcs[tid].idx < 29)) {
 
           // Instruct the PHY To combine the received data and attempt to decode it
           if (pid == HARQ_BCCH_PID) {
@@ -347,9 +347,10 @@ private:
       // Determine if it's a new transmission 5.3.2.2
       bool calc_is_new_transmission(Tgrant grant) {
 
-        if ((grant.ndi[tid] != cur_grant.ndi[tid])       || // 1st condition (NDI has changed)
-            (pid == HARQ_BCCH_PID && grant.rv[tid] == 0) || // 2nd condition (Broadcast and 1st transmission)
-             is_first_tb)                                   // 3rd condition (first TB)
+        if (grant.phy_grant.dl.mcs[tid].idx < 28 &&          // mcs 29,30,31 always retx regardless of rest
+            ((grant.ndi[tid] != cur_grant.ndi[tid])       || // 1st condition (NDI has changed)
+             (pid == HARQ_BCCH_PID && grant.rv[tid] == 0) || // 2nd condition (Broadcast and 1st transmission)
+             is_first_tb))
         {
           is_first_tb         = false;
           is_new_transmission = true;

srsue/hdr/mac/mac.h

@@ -135,7 +135,7 @@ private:
   demux         demux_unit; 
   
   /* DL/UL HARQ */
-  dl_harq_entity<MAC_NOF_HARQ_PROC+MOD_N_PROC, mac_grant_t, tb_action_dl_t, srslte_phy_grant_t> dl_harq;
+  dl_harq_entity<MAC_NOF_HARQ_PROC, mac_grant_t, tb_action_dl_t, srslte_phy_grant_t> dl_harq;
   ul_harq_entity<MAC_NOF_HARQ_PROC, mac_grant_t, tb_action_ul_t, srslte_phy_grant_t> ul_harq;
   
   /* MAC Uplink-related Procedures */

srsue/src/phy/phch_worker.cc

@@ -481,11 +481,7 @@ bool phch_worker::decode_pdcch_dl(srsue::mac_interface_phy::mac_grant_t* grant)
     /* Fill MAC grant structure */
     grant->ndi[0] = dci_unpacked.ndi;
     grant->ndi[1] = dci_unpacked.ndi_1;
-    if (tti < MOD_N_PROC) {
-      grant->pid = ASYNC_DL_SCHED?dci_unpacked.harq_process:tti+(2*HARQ_DELAY_MS);
-    } else {
-      grant->pid = ASYNC_DL_SCHED?dci_unpacked.harq_process:(tti%(2*HARQ_DELAY_MS));
-    }
+    grant->pid = ASYNC_DL_SCHED?dci_unpacked.harq_process:(tti%(2*HARQ_DELAY_MS));
     grant->n_bytes[0] = grant->phy_grant.dl.mcs[0].tbs / (uint32_t) 8;
     grant->n_bytes[1] = grant->phy_grant.dl.mcs[1].tbs / (uint32_t) 8;
     grant->tti = tti;