Add cell ID estimation using NSSS

openair1/PHY/LTE_TRANSPORT/nsss_NB_IoT.c

@@ -135,11 +135,139 @@ int generate_sss_NB_IoT(int32_t 				**txdataF,
   return(0);
 }
 
-// int rx_nsss_NB_IoT(PHY_VARS_UE_NB_IoT *ue)
-// {
-// 	uint8_t Nid2 = ue->common_vars.eNb_id;
-// 	NB_IoT_DL_FRAME_PARMS *frame_parms=&ue->frame_parms;
+int rx_nsss_NB_IoT(PHY_VARS_UE_NB_IoT *ue,int32_t *tot_metric)
+{
+
+	uint8_t Nid2,q_est,u_est;
+	NB_IoT_DL_FRAME_PARMS *frame_parms = &ue->frame_parms; 
+	int l,k,m; 
+	int16_t *d, *nsss_sf;
+	int32_t nsss_ext[2][132]; // up to 2 rx antennas ? 
+	int32_t metric; // correlation metric
+
+	// we suppose we are in NSSS subframe, after DFT
+	// this could be changed in further version
+	for (l=0;l<11;l++){
+		nsss_extract_NB_IoT(ue,frame_parms,nsss_ext,l);  
+	} 
+
+	// now do the Cell ID estimation based on the precomputed sequences in PHY/LTE_TRANSPORT/nsss_NB_IoT.h
+
+	*tot_metric = -99999999;
+	nsss_sf = (int16_t*)&nsss_ext[0][0];
+
+	for (Nid2=0;Nid2<16;Nid2++){
+
+		switch (Nid2) {
+		case 0:
+			d = d0f0;
+			break;
+		case 1:
+			d = d0f1;
+			break;
+		case 2:
+			d = d0f2;
+			break;
+		case 3:
+			d = d0f3;
+			break;
+		case 4:
+			d = d1f0;
+			break;
+		case 5:
+			d = d1f1;
+			break;
+		case 6:
+			d = d1f2;
+			break;
+		case 7:
+			d = d1f3;
+			break;
+		case 8:
+			d = d2f0;
+			break;
+		case 9:
+			d = d2f1;
+			break;
+		case 10:
+			d = d2f2;
+			break;
+		case 11:
+			d = d2f3;
+		case 12:
+			d = d3f0;
+			break;
+		case 13:
+			d = d3f1;
+			break;
+		case 14:
+			d = d3f2;
+			break;
+		case 15:
+			d = d3f3;
+			break;
+
+		default:
+			msg("[NSSS] ERROR\n");
+			return(-1);
+		}
+
+		for (k=0;k<126;k++){ 
+			metric = 0;  
+
+			for (m=0;m<132;m++){
+
+				metric += (int32_t)d[(k*126+m)<<1] * (int32_t)nsss_sf[(k*126+m)<<1] + 
+						(int32_t)d[((k*126+m)<<1)+1] * (int32_t)nsss_sf[((k*126+m)<<1)+1]; // real part of correlation
+
+			}
+
+			if (metric > *tot_metric){
+				q_est = Nid2/4; 
+				u_est = k; 
+				ue->frame_parms.Nid_cell = q_est*126 + u_est; 
+			}
 
-// 	return(0); 
-// }
+		}
+
+	}
+
+	return(0); 
+}
+
+int nsss_extract_NB_IoT(PHY_VARS_UE_NB_IoT *ue,
+						NB_IoT_DL_FRAME_PARMS *frame_parms,
+						int32_t **nsss_ext,
+						int l)
+{
+	uint8_t i,aarx; 
+	unsigned short  UL_RB_ID_NB_IoT; // index of RB dedicated to NB-IoT
+	int32_t *nsss_rxF,*nsssF_ext;
+	int32_t **rxdataF; 
+	int first_symbol_offset = 3; // NSSS starts at third symbol in subframe
+	
+	UL_RB_ID_NB_IoT = frame_parms->NB_IoT_RB_ID; 
+
+	for (aarx=0; aarx<frame_parms->nb_antennas_rx; aarx++) {
+
+		rxdataF  =  ue->common_vars.common_vars_rx_data_per_thread[0].rxdataF; // Note that 
+		nsssF_ext   = &nsss_ext[aarx][l*12];
+
+		if (UL_RB_ID_NB_IoT <= (frame_parms->N_RB_DL>>1)) { // NB-IoT RB is in the first half 
+          nsss_rxF       = &rxdataF[aarx][(UL_RB_ID_NB_IoT*12 + frame_parms->first_carrier_offset + ((l+first_symbol_offset)*(frame_parms->ofdm_symbol_size)))];
+        }// For second half of RBs skip DC carrier
+        else{ // NB-IoT RB is in the second half 
+          nsss_rxF       = &rxdataF[aarx][(1 + 6*(2*UL_RB_ID_NB_IoT - frame_parms->N_RB_DL) + ((l+first_symbol_offset)*(frame_parms->ofdm_symbol_size)))];
+          //dl_ch0++;
+        } 
+
+        for (i=0; i<12; i++) {
+              nsssF_ext[i]=nsss_rxF[i];
+        }
+
+	}
+
+	return(0); 
+
+}
 

openair1/PHY/LTE_TRANSPORT/proto_NB_IoT.h

@@ -51,7 +51,16 @@ int generate_sss_NB_IoT(int32_t                **txdataF,
                         uint16_t               symbol_offset,             // symbol_offset = 3 for NB-IoT 
                         uint16_t               slot_offset, 
                         unsigned short         frame_number,        // new attribute (Get value from higher layer), it does not exist for LTE
-                        unsigned short         RB_IoT_ID);          // new attribute (values are between 0.. Max_RB_number-1), it does not exist for LTE
+                        unsigned short         RB_IoT_ID);          // new attribute (values are between 0.. Max_RB_number-1), it does not exist for LTE 
+
+//*****************Vincent part for Cell ID estimation from NSSS ******************// 
+
+int rx_nsss_NB_IoT(PHY_VARS_UE_NB_IoT *ue,int32_t *tot_metric); 
+
+int nsss_extract_NB_IoT(PHY_VARS_UE_NB_IoT *ue,
+            NB_IoT_DL_FRAME_PARMS *frame_parms,
+            int32_t **nsss_ext,
+            int l);
 
 //NRS