Improved pdcch decoding

srslte/lib/fec/viterbi.c

@@ -40,7 +40,7 @@
 
 #define TB_ITER 3
 
-#define DEFAULT_GAIN 20
+#define DEFAULT_GAIN 16
 
 //#undef LV_HAVE_SSE
 

srslte/lib/phch/cqi.c

@@ -145,7 +145,7 @@ bool srslte_cqi_send(uint32_t I_cqi_pmi, uint32_t tti) {
 //static float cqi_to_snr_table[15] = { 1.95, 4, 6, 8, 10, 11.95, 14.05, 16, 17.9, 19.9, 21.5, 23.45, 25.0, 27.30, 29};
 
 // From experimental measurements @ 5 MHz 
-static float cqi_to_snr_table[15] = { 0, 1.25, 2.5, 3.75, 5, 6, 7.5, 9, 11.5, 13.0, 15.0, 18, 20, 22.5, 26.5};
+static float cqi_to_snr_table[15] = { 1, 1.75, 3, 4, 5, 6, 7.5, 9, 11.5, 13.0, 15.0, 18, 20, 22.5, 26.5};
 
 uint8_t srslte_cqi_from_snr(float snr)
 {

srslte/lib/phch/pdcch.c

@@ -273,8 +273,10 @@ static int dci_decode(srslte_pdcch_t *q, float *e, uint8_t *data, uint32_t E, ui
   {
     bzero(q->rm_f, sizeof(float)*3 * (SRSLTE_DCI_MAX_BITS + 16));
     
+    uint32_t coded_len = 3 * (nof_bits + 16); 
+    
     /* unrate matching */
-    srslte_rm_conv_rx(e, E, q->rm_f, 3 * (nof_bits + 16));
+    srslte_rm_conv_rx(e, E, q->rm_f, coded_len);
     
     /* viterbi decoder */
     srslte_viterbi_decode_f(&q->decoder, q->rm_f, data, nof_bits + 16);
@@ -286,6 +288,7 @@ static int dci_decode(srslte_pdcch_t *q, float *e, uint8_t *data, uint32_t E, ui
     if (crc) {
       *crc = p_bits ^ crc_res; 
     }
+        
     return SRSLTE_SUCCESS;
   } else {
     fprintf(stderr, "Invalid parameters: E: %d, max_bits: %d, nof_bits: %d\n", E, q->max_bits, nof_bits);
@@ -399,7 +402,7 @@ int srslte_pdcch_extract_llr(srslte_pdcch_t *q, cf_t *sf_symbols, cf_t *ce[SRSLT
     /* in control channels, only diversity is supported */
     if (q->cell.nof_ports == 1) {
       /* no need for layer demapping */
-      srslte_predecoding_single(q->symbols[0], q->ce[0], q->d, nof_symbols, noise_estimate);
+      srslte_predecoding_single(q->symbols[0], q->ce[0], q->d, nof_symbols, noise_estimate/2);
     } else {
       srslte_predecoding_diversity(q->symbols[0], q->ce, x, q->cell.nof_ports, nof_symbols);
       srslte_layerdemap_diversity(x, q->d, q->cell.nof_ports, nof_symbols / q->cell.nof_ports);

srslte/lib/ue/ue_dl.c

@@ -402,7 +402,7 @@ int srslte_ue_dl_decode_rnti_rv(srslte_ue_dl_t *q, cf_t *input, uint8_t *data, u
     return ret; 
   }
   
-  if (srslte_pdcch_extract_llr(&q->pdcch, q->sf_symbols, q->ce, 0, sf_idx, q->cfi)) {
+  if (srslte_pdcch_extract_llr(&q->pdcch, q->sf_symbols, q->ce, srslte_chest_dl_get_noise_estimate(&q->chest), sf_idx, q->cfi)) {
     fprintf(stderr, "Error extracting LLRs\n");
     return SRSLTE_ERROR;
   }