Compute LLR for QPSK for ML

openair1/PHY/NR_TRANSPORT/nr_transport_proto.h

@@ -292,6 +292,18 @@ void nr_ulsch_compute_llr(int32_t *rxdataF_comp,
 void reset_active_stats(PHY_VARS_gNB *gNB, int frame);
 void reset_active_ulsch(PHY_VARS_gNB *gNB, int frame);
 
+void nr_ulsch_compute_ML_llr(int32_t **rxdataF_comp,
+                             int32_t ***rho,
+                             int16_t **llr_layers,
+                             uint8_t nb_antennas_rx,
+                             uint32_t rb_size,
+                             uint32_t nb_re,
+                             uint8_t symbol,
+                             uint32_t rxdataF_ext_offset,
+                             uint8_t mod_order);
+
+void nr_ulsch_shift_llr(int16_t **llr_layers, uint32_t nb_re, uint32_t rxdataF_ext_offset, uint8_t mod_order, int shift);
+
 void nr_fill_ulsch(PHY_VARS_gNB *gNB,
                    int frame,
                    int slot,

openair1/PHY/NR_TRANSPORT/nr_ulsch_demodulation.c

@@ -12,6 +12,7 @@
 //#define DEBUG_CH_COMP
 //#define DEBUG_RB_EXT
 //#define DEBUG_CH_MAG
+//#define ML_DEBUG
 
 #define INVALID_VALUE 255
 
@@ -636,7 +637,7 @@ void nr_ulsch_channel_compensation(int **rxdataF_ext,
       QAM_amp128 = _mm_set1_epi16(QAM16_n1);  // 2/sqrt(10)
       QAM_amp128b = _mm_setzero_si128();
       QAM_amp128c = _mm_setzero_si128();
-    } 
+    }
     else if (mod_order == 6) {
       QAM_amp128  = _mm_set1_epi16(QAM64_n1); //
       QAM_amp128b = _mm_set1_epi16(QAM64_n2);
@@ -1081,7 +1082,7 @@ void nr_ulsch_detection_mrc(NR_DL_FRAME_PARMS *frame_parms,
                 int32_t **ul_ch_mag,
                 int32_t **ul_ch_magb,
                 int32_t **ul_ch_magc,
-                int32_t ***rho,                
+                int32_t ***rho,
                 uint8_t  nrOfLayers,
                 uint8_t symbol,
                 uint16_t nb_rb,
@@ -1115,7 +1116,7 @@ void nr_ulsch_detection_mrc(NR_DL_FRAME_PARMS *frame_parms,
         ul_ch_mag128[1]      = (__m128i *)&ul_ch_mag[aatx*frame_parms->nb_antennas_rx+aa][(symbol*(nb_re + off))];
         ul_ch_mag128b[1]     = (__m128i *)&ul_ch_magb[aatx*frame_parms->nb_antennas_rx+aa][(symbol*(nb_re + off))];
         ul_ch_mag128c[1]     = (__m128i *)&ul_ch_magc[aatx*frame_parms->nb_antennas_rx+aa][(symbol*(nb_re + off))];
-      
+
         // MRC on each re of rb, both on MF output and magnitude (for 16QAM/64QAM llr computation)
         for (i=0; i<nb_rb_0*3; i++) {
             rxdataF_comp128[0][i] = _mm_adds_epi16(rxdataF_comp128[0][i],rxdataF_comp128[1][i]);
@@ -1898,6 +1899,9 @@ void nr_rx_pusch(PHY_VARS_gNB *gNB,
                  unsigned char harq_pid)
 {
 
+  // Temporary flag: (true) ML receiver, (false) MMSE receiver
+  bool ml_rx = true;
+
   uint8_t aarx, aatx;
   uint32_t nb_re_pusch, bwp_start_subcarrier;
   int avgs = 0;
@@ -2001,8 +2005,8 @@ void nr_rx_pusch(PHY_VARS_gNB *gNB,
   int ad_shift = 0;
   if (rel15_ul->nrOfLayers == 1) {
     ad_shift = 1 + log2_approx(frame_parms->nb_antennas_rx >> 2);
-  } else {
-    ad_shift = -3; // For 2-layers, we are already doing a bit shift in the nr_ulsch_zero_forcing_rx_2layers() function, so we can use more bits
+  } else if (ml_rx == false) {
+    ad_shift = -3; // For 2-layers, we are already doing a bit shift in the nr_ulsch_mmse_2layers() function, so we can use more bits
   }
 
   for(uint8_t symbol = rel15_ul->start_symbol_index; symbol < (rel15_ul->start_symbol_index + rel15_ul->nr_of_symbols); symbol++) {
@@ -2108,7 +2112,7 @@ void nr_rx_pusch(PHY_VARS_gNB *gNB,
                              nb_re_pusch);
 
       // Apply MMSE for 2 Tx layers
-      if (rel15_ul->nrOfLayers == 2) {
+      if (ml_rx == false && rel15_ul->nrOfLayers == 2) {
         nr_ulsch_mmse_2layers(frame_parms,
                               pusch_vars->rxdataF_comp,
                               pusch_vars->ul_ch_mag0,
@@ -2159,16 +2163,45 @@ void nr_rx_pusch(PHY_VARS_gNB *gNB,
       /*--------------------  LLRs computation  -------------------------------------------------------------*/
       /*-----------------------------------------------------------------------------------------------------*/
       start_meas(&gNB->ulsch_llr_stats);
-      for (aatx=0; aatx < rel15_ul->nrOfLayers; aatx++) {
-        nr_ulsch_compute_llr(&pusch_vars->rxdataF_comp[aatx*frame_parms->nb_antennas_rx][symbol * (off + rel15_ul->rb_size * NR_NB_SC_PER_RB)],
-                             pusch_vars->ul_ch_mag0[aatx*frame_parms->nb_antennas_rx],
-                             pusch_vars->ul_ch_magb0[aatx*frame_parms->nb_antennas_rx],
-                             pusch_vars->ul_ch_magc0[aatx*frame_parms->nb_antennas_rx],
-                             &pusch_vars->llr_layers[aatx][rxdataF_ext_offset * rel15_ul->qam_mod_order],
-                             rel15_ul->rb_size,
-                             pusch_vars->ul_valid_re_per_slot[symbol],
-                             symbol,
-                             rel15_ul->qam_mod_order);
+      if (ml_rx == false || rel15_ul->nrOfLayers == 1) {
+        for (aatx=0; aatx < rel15_ul->nrOfLayers; aatx++) {
+          nr_ulsch_compute_llr(&pusch_vars->rxdataF_comp[aatx * frame_parms->nb_antennas_rx][symbol * (off + rel15_ul->rb_size * NR_NB_SC_PER_RB)],
+                               pusch_vars->ul_ch_mag0[aatx * frame_parms->nb_antennas_rx],
+                               pusch_vars->ul_ch_magb0[aatx * frame_parms->nb_antennas_rx],
+                               pusch_vars->ul_ch_magc0[aatx * frame_parms->nb_antennas_rx],
+                               &pusch_vars->llr_layers[aatx][rxdataF_ext_offset * rel15_ul->qam_mod_order],
+                               rel15_ul->rb_size,
+                               pusch_vars->ul_valid_re_per_slot[symbol],
+                               symbol,
+                               rel15_ul->qam_mod_order);
+        }
+      } else {
+        nr_ulsch_compute_ML_llr(pusch_vars->rxdataF_comp,
+                                pusch_vars->rho,
+                                pusch_vars->llr_layers,
+                                frame_parms->nb_antennas_rx,
+                                rel15_ul->rb_size,
+                                nb_re_pusch,
+                                symbol,
+                                rxdataF_ext_offset,
+                                rel15_ul->qam_mod_order);
+
+        if (rel15_ul->qam_mod_order == 2) {
+          nr_ulsch_shift_llr(pusch_vars->llr_layers, nb_re_pusch, rxdataF_ext_offset, rel15_ul->qam_mod_order, 4);
+        }
+
+#ifdef ML_DEBUG
+        c16_t *llr_layers0 = (c16_t *)&pusch_vars->llr_layers[0][rxdataF_ext_offset * rel15_ul->qam_mod_order];
+        c16_t *llr_layers1 = (c16_t *)&pusch_vars->llr_layers[1][rxdataF_ext_offset * rel15_ul->qam_mod_order];
+        printf("===============================\n");
+        printf("AFTER nr_ulsch_compute_ML_llr()\n");
+        printf("===============================\n");
+        for (int k = 0; k < nb_re_pusch; k++) {
+          printf("[%3i] llr_layers0 = (%6i, %6i), llr_layers1 = (%6i, %6i)\n",
+                 k, llr_layers0[k].r, llr_layers0[k].i, llr_layers1[k].r, llr_layers1[k].i);
+        }
+        printf("\n");
+#endif
       }
       stop_meas(&gNB->ulsch_llr_stats);
       rxdataF_ext_offset += pusch_vars->ul_valid_re_per_slot[symbol];