Fixed DL channel estimator for ports 3&4

lib/src/phy/ch_estimation/chest_dl.c

@@ -390,11 +390,12 @@ static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t
       }
     } else {
       if (q->average_subframe) {
-        fidx_offset = SRSLTE_MIN(srslte_refsignal_cs_fidx(q->cell, 0, port_id, 0),
-                                 srslte_refsignal_cs_fidx(q->cell, 1, port_id, 0));
-        srslte_interp_linear_offset(&q->srslte_interp_lin_3, &pilot_estimates[q->cell.nof_prb * l],
-                                    &ce[srslte_refsignal_cs_nsymbol(l, q->cell.cp, port_id) * q->cell.nof_prb
-                                        * SRSLTE_NRE], fidx_offset, SRSLTE_NRE / 4 - fidx_offset);
+        fidx_offset = q->cell.id % 3;
+        srslte_interp_linear_offset(&q->srslte_interp_lin_3,
+                                    pilot_estimates,
+                                    ce,
+                                    fidx_offset,
+                                    SRSLTE_NRE / 4 - fidx_offset);
       } else {
         fidx_offset = srslte_refsignal_cs_fidx(q->cell, l, port_id, 0);
         srslte_interp_linear_offset(&q->srslte_interp_lin, &pilot_estimates[2 * q->cell.nof_prb * l],
@@ -407,7 +408,7 @@ static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t
   /* Now interpolate in the time domain between symbols */
   if (q->average_subframe) {
     // If we average per subframe, just copy the estimates in the time domain
-    for (l=0;l<2*SRSLTE_CP_NSYMB(q->cell.cp);l++) {
+    for (l=1;l<2*SRSLTE_CP_NSYMB(q->cell.cp);l++) {
       memcpy(&ce[l*SRSLTE_NRE*q->cell.nof_prb], ce, sizeof(cf_t)*SRSLTE_NRE*q->cell.nof_prb);
     }
   } else {

lib/src/phy/ch_estimation/refsignal_dl.c

@@ -56,17 +56,17 @@ uint32_t srslte_refsignal_cs_v(uint32_t port_id, uint32_t ref_symbol_idx)
       }
       break;
     case 2:
-      if (ref_symbol_idx < 2) {
+      if (ref_symbol_idx == 0) {
         v = 0;
       } else {
         v = 3;
       }
       break;
     case 3:
-      if (ref_symbol_idx < 2) {
+      if (ref_symbol_idx == 0) {
         v = 3;
       } else {
-        v = 6;
+        v = 0;
       }
       break;
   }
@@ -414,7 +414,7 @@ int srslte_refsignal_cs_get_sf(srslte_cell_t cell, uint32_t port_id, cf_t *sf_sy
     for (l=0;l<srslte_refsignal_cs_nof_symbols(port_id);l++) {
       uint32_t nsymbol = srslte_refsignal_cs_nsymbol(l, cell.cp, port_id);
       /* Compute offset frequency index */
-      fidx = ((srslte_refsignal_cs_v(port_id, l) + (cell.id % 6)) % 6); 
+      fidx = srslte_refsignal_cs_fidx(cell, l, port_id, 0);
       for (i = 0; i < 2*cell.nof_prb; i++) {
         pilots[SRSLTE_REFSIGNAL_PILOT_IDX(i,l,cell)] = sf_symbols[SRSLTE_RE_IDX(cell.nof_prb, nsymbol, fidx)];
         fidx += SRSLTE_NRE/2;       // 2 references per PRB