/* * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The OpenAirInterface Software Alliance licenses this file to You under * the OAI Public License, Version 1.1 (the "License"); you may not use this file * except in compliance with the License. * You may obtain a copy of the License at * * http://www.openairinterface.org/?page_id=698 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *------------------------------------------------------------------------------- * For more information about the OpenAirInterface (OAI) Software Alliance: * contact@openairinterface.org */ /* file: lte_sync_time.c purpose: coarse timing synchronization for LTE (using PSS) author: florian.kaltenberger@eurecom.fr, oscar.tonelli@yahoo.it date: 22.10.2009 */ //#include <string.h> #include <math.h> #include "PHY/defs_UE.h" #include "PHY/phy_extern_ue.h" #include "PHY/LTE_REFSIG/lte_refsig.h" // Note: this is for prototype of generate_drs_pusch (OTA synchronization of RRUs) #include "PHY/LTE_UE_TRANSPORT/transport_proto_ue.h" int* sync_corr_ue0 = NULL; int* sync_corr_ue1 = NULL; int* sync_corr_ue2 = NULL; int sync_tmp[2048*4] __attribute__((aligned(32))); short syncF_tmp[2048*2] __attribute__((aligned(32))); int lte_sync_time_init(LTE_DL_FRAME_PARMS *frame_parms ) // LTE_UE_COMMON *common_vars { int i,k; sync_corr_ue0 = (int *)malloc16(LTE_NUMBER_OF_SUBFRAMES_PER_FRAME*sizeof(int)*frame_parms->samples_per_tti); sync_corr_ue1 = (int *)malloc16(LTE_NUMBER_OF_SUBFRAMES_PER_FRAME*sizeof(int)*frame_parms->samples_per_tti); sync_corr_ue2 = (int *)malloc16(LTE_NUMBER_OF_SUBFRAMES_PER_FRAME*sizeof(int)*frame_parms->samples_per_tti); if (sync_corr_ue0) { #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue allocated at %p\n", sync_corr_ue0); #endif //common_vars->sync_corr = sync_corr; } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue0 not allocated\n"); return(-1); } if (sync_corr_ue1) { #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue allocated at %p\n", sync_corr_ue1); #endif //common_vars->sync_corr = sync_corr; } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue1 not allocated\n"); return(-1); } if (sync_corr_ue2) { #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue allocated at %p\n", sync_corr_ue2); #endif //common_vars->sync_corr = sync_corr; } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] sync_corr_ue2 not allocated\n"); return(-1); } // primary_synch0_time = (int *)malloc16((frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); primary_synch0_time = (int16_t *)malloc16((frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); if (primary_synch0_time) { // bzero(primary_synch0_time,(frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); bzero(primary_synch0_time,(frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] primary_synch0_time allocated at %p\n", primary_synch0_time); #endif } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] primary_synch0_time not allocated\n"); return(-1); } // primary_synch1_time = (int *)malloc16((frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); primary_synch1_time = (int16_t *)malloc16((frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); if (primary_synch1_time) { // bzero(primary_synch1_time,(frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); bzero(primary_synch1_time,(frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] primary_synch1_time allocated at %p\n", primary_synch1_time); #endif } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] primary_synch1_time not allocated\n"); return(-1); } // primary_synch2_time = (int *)malloc16((frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); primary_synch2_time = (int16_t *)malloc16((frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); if (primary_synch2_time) { // bzero(primary_synch2_time,(frame_parms->ofdm_symbol_size+frame_parms->nb_prefix_samples)*sizeof(int)); bzero(primary_synch2_time,(frame_parms->ofdm_symbol_size)*sizeof(int16_t)*2); #ifdef DEBUG_PHY LOG_D(PHY,"[openair][LTE_PHY][SYNC] primary_synch2_time allocated at %p\n", primary_synch2_time); #endif } else { LOG_E(PHY,"[openair][LTE_PHY][SYNC] primary_synch2_time not allocated\n"); return(-1); } // generate oversampled sync_time sequences k=frame_parms->ofdm_symbol_size-36; for (i=0; i<72; i++) { syncF_tmp[2*k] = primary_synch0[2*i]>>2; //we need to shift input to avoid overflow in fft syncF_tmp[2*k+1] = primary_synch0[2*i+1]>>2; k++; if (k >= frame_parms->ofdm_symbol_size) { k++; // skip DC carrier k-=frame_parms->ofdm_symbol_size; } } switch (frame_parms->N_RB_DL) { case 6: idft(IDFT_128,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 25: idft(IDFT_512,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 50: idft(IDFT_1024,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 75: idft(IDFT_1536,(short*)syncF_tmp, /// complex input (short*)sync_tmp, 1); /// complex output break; case 100: idft(IDFT_2048,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; default: LOG_E(PHY,"Unsupported N_RB_DL %d\n",frame_parms->N_RB_DL); break; } for (i=0; i<frame_parms->ofdm_symbol_size; i++) ((int32_t*)primary_synch0_time)[i] = sync_tmp[i]; k=frame_parms->ofdm_symbol_size-36; for (i=0; i<72; i++) { syncF_tmp[2*k] = primary_synch1[2*i]>>2; //we need to shift input to avoid overflow in fft syncF_tmp[2*k+1] = primary_synch1[2*i+1]>>2; k++; if (k >= frame_parms->ofdm_symbol_size) { k++; // skip DC carrier k-=frame_parms->ofdm_symbol_size; } } switch (frame_parms->N_RB_DL) { case 6: idft(IDFT_128,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 25: idft(IDFT_512,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 50: idft(IDFT_1024,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 75: idft(IDFT_1536,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 100: idft(IDFT_2048,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; default: LOG_E(PHY,"Unsupported N_RB_DL %d\n",frame_parms->N_RB_DL); break; } for (i=0; i<frame_parms->ofdm_symbol_size; i++) ((int32_t*)primary_synch1_time)[i] = sync_tmp[i]; k=frame_parms->ofdm_symbol_size-36; for (i=0; i<72; i++) { syncF_tmp[2*k] = primary_synch2[2*i]>>2; //we need to shift input to avoid overflow in fft syncF_tmp[2*k+1] = primary_synch2[2*i+1]>>2; k++; if (k >= frame_parms->ofdm_symbol_size) { k++; // skip DC carrier k-=frame_parms->ofdm_symbol_size; } } switch (frame_parms->N_RB_DL) { case 6: idft(IDFT_128,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 25: idft(IDFT_512,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 50: idft(IDFT_1024,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 75: idft(IDFT_1536,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; case 100: idft(IDFT_2048,(short*)syncF_tmp, /// complex input (short*)sync_tmp, /// complex output 1); break; default: LOG_E(PHY,"Unsupported N_RB_DL %d\n",frame_parms->N_RB_DL); break; } for (i=0; i<frame_parms->ofdm_symbol_size; i++) ((int32_t*)primary_synch2_time)[i] = sync_tmp[i]; if ( LOG_DUMPFLAG(DEBUG_LTEESTIM)){ LOG_M("primary_sync0.m","psync0",primary_synch0_time,frame_parms->ofdm_symbol_size,1,1); LOG_M("primary_sync1.m","psync1",primary_synch1_time,frame_parms->ofdm_symbol_size,1,1); LOG_M("primary_sync2.m","psync2",primary_synch2_time,frame_parms->ofdm_symbol_size,1,1); } return (1); } void lte_sync_time_free(void) { if (sync_corr_ue0) { LOG_D(PHY,"Freeing sync_corr_ue (%p)...\n",sync_corr_ue0); free(sync_corr_ue0); } if (sync_corr_ue1) { LOG_D(PHY,"Freeing sync_corr_ue (%p)...\n",sync_corr_ue1); free(sync_corr_ue1); } if (sync_corr_ue2) { LOG_D(PHY,"Freeing sync_corr_ue (%p)...\n",sync_corr_ue2); free(sync_corr_ue2); } if (primary_synch0_time) { LOG_D(PHY,"Freeing primary_sync0_time ...\n"); free(primary_synch0_time); } if (primary_synch1_time) { LOG_D(PHY,"Freeing primary_sync1_time ...\n"); free(primary_synch1_time); } if (primary_synch2_time) { LOG_D(PHY,"Freeing primary_sync2_time ...\n"); free(primary_synch2_time); } sync_corr_ue0 = NULL; sync_corr_ue1 = NULL; sync_corr_ue2 = NULL; primary_synch0_time = NULL; primary_synch1_time = NULL; primary_synch2_time = NULL; } static inline int abs32(int x) { return (((int)((short*)&x)[0])*((int)((short*)&x)[0]) + ((int)((short*)&x)[1])*((int)((short*)&x)[1])); } #define SHIFT 17 int lte_sync_time(int **rxdata, ///rx data in time domain LTE_DL_FRAME_PARMS *frame_parms, int *eNB_id) { // perform a time domain correlation using the oversampled sync sequence unsigned int n, ar, s, peak_pos, peak_val, sync_source; int result,result2; int sync_out[3] = {0,0,0},sync_out2[3] = {0,0,0}; int tmp[3] = {0,0,0}; int length = LTE_NUMBER_OF_SUBFRAMES_PER_FRAME*frame_parms->samples_per_tti>>1; //LOG_D(PHY,"[SYNC TIME] Calling sync_time.\n"); AssertFatal(sync_corr_ue0 != NULL, "sync_corr_ue0 not yet allocated! Exiting.\n"); AssertFatal(sync_corr_ue1 != NULL, "sync_corr_ue0 not yet allocated! Exiting.\n"); AssertFatal(sync_corr_ue2 != NULL, "sync_corr_ue0 not yet allocated! Exiting.\n"); peak_val = 0; peak_pos = 0; sync_source = 0; for (n=0; n<length; n+=4) { sync_corr_ue0[n] = 0; sync_corr_ue0[n+length] = 0; sync_corr_ue1[n] = 0; sync_corr_ue1[n+length] = 0; sync_corr_ue2[n] = 0; sync_corr_ue2[n+length] = 0; for (s=0; s<3; s++) { sync_out[s]=0; sync_out2[s]=0; } // if (n<(length-frame_parms->ofdm_symbol_size-frame_parms->nb_prefix_samples)) { if (n<(length-frame_parms->ofdm_symbol_size)) { //calculate dot product of primary_synch0_time and rxdata[ar][n] (ar=0..nb_ant_rx) and store the sum in temp[n]; for (ar=0; ar<frame_parms->nb_antennas_rx; ar++) { result = dot_product((short*)primary_synch0_time, (short*) &(rxdata[ar][n]), frame_parms->ofdm_symbol_size, SHIFT); result2 = dot_product((short*)primary_synch0_time, (short*) &(rxdata[ar][n+length]), frame_parms->ofdm_symbol_size, SHIFT); ((short*)sync_corr_ue0)[2*n] += ((short*) &result)[0]; ((short*)sync_corr_ue0)[2*n+1] += ((short*) &result)[1]; ((short*)sync_corr_ue0)[2*(length+n)] += ((short*) &result2)[0]; ((short*)sync_corr_ue0)[(2*(length+n))+1] += ((short*) &result2)[1]; ((short*)sync_out)[0] += ((short*) &result)[0]; ((short*)sync_out)[1] += ((short*) &result)[1]; ((short*)sync_out2)[0] += ((short*) &result2)[0]; ((short*)sync_out2)[1] += ((short*) &result2)[1]; } for (ar=0; ar<frame_parms->nb_antennas_rx; ar++) { result = dot_product((short*)primary_synch1_time, (short*) &(rxdata[ar][n]), frame_parms->ofdm_symbol_size, SHIFT); result2 = dot_product((short*)primary_synch1_time, (short*) &(rxdata[ar][n+length]), frame_parms->ofdm_symbol_size, SHIFT); ((short*)sync_corr_ue1)[2*n] += ((short*) &result)[0]; ((short*)sync_corr_ue1)[2*n+1] += ((short*) &result)[1]; ((short*)sync_corr_ue1)[2*(length+n)] += ((short*) &result2)[0]; ((short*)sync_corr_ue1)[(2*(length+n))+1] += ((short*) &result2)[1]; ((short*)sync_out)[2] += ((short*) &result)[0]; ((short*)sync_out)[3] += ((short*) &result)[1]; ((short*)sync_out2)[2] += ((short*) &result2)[0]; ((short*)sync_out2)[3] += ((short*) &result2)[1]; } for (ar=0; ar<frame_parms->nb_antennas_rx; ar++) { result = dot_product((short*)primary_synch2_time, (short*) &(rxdata[ar][n]), frame_parms->ofdm_symbol_size, SHIFT); result2 = dot_product((short*)primary_synch2_time, (short*) &(rxdata[ar][n+length]), frame_parms->ofdm_symbol_size, SHIFT); ((short*)sync_corr_ue2)[2*n] += ((short*) &result)[0]; ((short*)sync_corr_ue2)[2*n+1] += ((short*) &result)[1]; ((short*)sync_corr_ue2)[2*(length+n)] += ((short*) &result2)[0]; ((short*)sync_corr_ue2)[(2*(length+n))+1] += ((short*) &result2)[1]; ((short*)sync_out)[4] += ((short*) &result)[0]; ((short*)sync_out)[5] += ((short*) &result)[1]; ((short*)sync_out2)[4] += ((short*) &result2)[0]; ((short*)sync_out2)[5] += ((short*) &result2)[1]; } } // calculate the absolute value of sync_corr[n] sync_corr_ue0[n] = abs32(sync_corr_ue0[n]); sync_corr_ue0[n+length] = abs32(sync_corr_ue0[n+length]); sync_corr_ue1[n] = abs32(sync_corr_ue1[n]); sync_corr_ue1[n+length] = abs32(sync_corr_ue1[n+length]); sync_corr_ue2[n] = abs32(sync_corr_ue2[n]); sync_corr_ue2[n+length] = abs32(sync_corr_ue2[n+length]); for (s=0; s<3; s++) { tmp[s] = (abs32(sync_out[s])>>1) + (abs32(sync_out2[s])>>1); if (tmp[s]>peak_val) { peak_val = tmp[s]; peak_pos = n; sync_source = s; /* printf("s %d: n %d sync_out %d, sync_out2 %d (sync_corr %d,%d), (%d,%d) (%d,%d)\n",s,n,abs32(sync_out[s]),abs32(sync_out2[s]),sync_corr_ue0[n], sync_corr_ue0[n+length],((int16_t*)&sync_out[s])[0],((int16_t*)&sync_out[s])[1],((int16_t*)&sync_out2[s])[0],((int16_t*)&sync_out2[s])[1]); */ } } } *eNB_id = sync_source; LOG_I(PHY,"[UE] lte_sync_time: Sync source = %d, Peak found at pos %d, val = %d (%d dB)\n",sync_source,peak_pos,peak_val,dB_fixed(peak_val)/2); if ( LOG_DUMPFLAG(DEBUG_LTEESTIM)){ static int debug_cnt; if (debug_cnt == 0) { LOG_M("sync_corr0_ue.m","synccorr0",sync_corr_ue0,2*length,1,2); LOG_M("sync_corr1_ue.m","synccorr1",sync_corr_ue1,2*length,1,2); LOG_M("sync_corr2_ue.m","synccorr2",sync_corr_ue2,2*length,1,2); LOG_M("rxdata0.m","rxd0",rxdata[0],length<<1,1,1); // exit(-1); } else { debug_cnt++; } } return(peak_pos); } int ru_sync_time_init(RU_t *ru) // LTE_UE_COMMON *common_vars { /* int16_t dmrs[2048]; int16_t *dmrsp[2] = {dmrs,NULL}; */ int32_t dmrs[ru->frame_parms->ofdm_symbol_size*14] __attribute__((aligned(32))); //int32_t *dmrsp[2] = {&dmrs[(3-ru->frame_parms->Ncp)*ru->frame_parms->ofdm_symbol_size],NULL}; int32_t *dmrsp[2] = {&dmrs[0],NULL}; generate_ul_ref_sigs(); ru->dmrssync = (int16_t*)malloc16_clear(ru->frame_parms->ofdm_symbol_size*2*sizeof(int16_t)); ru->dmrs_corr = (uint64_t*)malloc16_clear(ru->frame_parms->samples_per_tti*10*sizeof(uint64_t)); generate_drs_pusch(NULL, NULL, ru->frame_parms, dmrsp, 0, AMP, 0, 0, ru->frame_parms->N_RB_DL, 0); switch (ru->frame_parms->N_RB_DL) { case 6: idft(IDFT_128,(int16_t*)(&dmrsp[0][3*ru->frame_parms->ofdm_symbol_size]), ru->dmrssync, /// complex output 1); break; case 25: idft(IDFT_512,(int16_t*)(&dmrsp[0][3*ru->frame_parms->ofdm_symbol_size]), ru->dmrssync, /// complex output 1); break; case 50: idft(IDFT_1024,(int16_t*)(&dmrsp[0][3*ru->frame_parms->ofdm_symbol_size]), ru->dmrssync, /// complex output 1); break; case 75: idft(IDFT_1536,(int16_t*)(&dmrsp[0][3*ru->frame_parms->ofdm_symbol_size]), ru->dmrssync, 1); /// complex output break; case 100: idft(IDFT_2048,(int16_t*)(&dmrsp[0][3*ru->frame_parms->ofdm_symbol_size]), ru->dmrssync, /// complex output 1); break; default: AssertFatal(1==0,"Unsupported N_RB_DL %d\n",ru->frame_parms->N_RB_DL); break; } return(0); } void ru_sync_time_free(RU_t *ru) { AssertFatal(ru->dmrssync!=NULL,"ru->dmrssync is NULL\n"); free(ru->dmrssync); if (ru->dmrs_corr) free(ru->dmrs_corr); } //#define DEBUG_PHY int lte_sync_time_eNB(int32_t **rxdata, ///rx data in time domain LTE_DL_FRAME_PARMS *frame_parms, uint32_t length, uint32_t *peak_val_out, uint32_t *sync_corr_eNB) { // perform a time domain correlation using the oversampled sync sequence unsigned int n, ar, peak_val, peak_pos; uint64_t mean_val; int result; short *primary_synch_time; int eNB_id = frame_parms->Nid_cell%3; // LOG_E(PHY,"[SYNC TIME] Calling sync_time_eNB(%p,%p,%d,%d)\n",rxdata,frame_parms,eNB_id,length); if (sync_corr_eNB == NULL) { LOG_E(PHY,"[SYNC TIME] sync_corr_eNB not yet allocated! Exiting.\n"); return(-1); } switch (eNB_id) { case 0: primary_synch_time = (short*)primary_synch0_time; break; case 1: primary_synch_time = (short*)primary_synch1_time; break; case 2: primary_synch_time = (short*)primary_synch2_time; break; default: LOG_E(PHY,"[SYNC TIME] Illegal eNB_id!\n"); return (-1); } peak_val = 0; peak_pos = 0; mean_val = 0; for (n=0; n<length; n+=4) { sync_corr_eNB[n] = 0; if (n<(length-frame_parms->ofdm_symbol_size-frame_parms->nb_prefix_samples)) { //calculate dot product of primary_synch0_time and rxdata[ar][n] (ar=0..nb_ant_rx) and store the sum in temp[n]; for (ar=0; ar<frame_parms->nb_antennas_rx; ar++) { result = dot_product((short*)primary_synch_time, (short*) &(rxdata[ar][n]), frame_parms->ofdm_symbol_size, SHIFT); //((short*)sync_corr)[2*n] += ((short*) &result)[0]; //((short*)sync_corr)[2*n+1] += ((short*) &result)[1]; sync_corr_eNB[n] += abs32(result); } } /* if (eNB_id == 2) { printf("sync_time_eNB %d : %d,%d (%d)\n",n,sync_corr_eNB[n],mean_val, peak_val); } */ mean_val += sync_corr_eNB[n]; if (sync_corr_eNB[n]>peak_val) { peak_val = sync_corr_eNB[n]; peak_pos = n; } } mean_val/=length; *peak_val_out = peak_val; if (peak_val <= (40*(uint32_t)mean_val)) { LOG_I(PHY,"[SYNC TIME] No peak found (%u,%u,%"PRIu64",%"PRIu64")\n",peak_pos,peak_val,mean_val,40*mean_val); return(-1); } else { LOG_I(PHY,"[SYNC TIME] Peak found at pos %u, val = %u, mean_val = %"PRIu64"\n",peak_pos,peak_val,mean_val); return(peak_pos); } } static inline int64_t abs64(int64_t x) { return (((int64_t)((int32_t*)&x)[0])*((int64_t)((int32_t*)&x)[0]) + ((int64_t) ((int32_t*)&x)[1])*((int64_t)((int32_t*)&x)[1])); } int ru_sync_time(RU_t *ru, int64_t *lev, int64_t *avg) { LTE_DL_FRAME_PARMS *frame_parms = ru->frame_parms; RU_CALIBRATION *calibration = &ru->calibration; // perform a time domain correlation using the oversampled sync sequence int length = LTE_NUMBER_OF_SUBFRAMES_PER_FRAME*frame_parms->samples_per_tti; // circular copy of beginning to end of rxdata buffer. Note: buffer should be big enough upon calling this function for (int ar=0;ar<ru->nb_rx;ar++) memcpy((void*)&ru->common.rxdata[ar][2*length], (void*)&ru->common.rxdata[ar][0], frame_parms->ofdm_symbol_size); int32_t maxlev0=0; int maxpos0=0; int64_t avg0=0; int64_t result; int64_t dmrs_corr; int maxval=0; for (int i=0;i<2*(frame_parms->ofdm_symbol_size);i++) { maxval = max(maxval,ru->dmrssync[i]); maxval = max(maxval,-ru->dmrssync[i]); } if (ru->state == RU_CHECK_SYNC) { for (int i=0;i<2*(frame_parms->ofdm_symbol_size);i++) { maxval = max(maxval,calibration->drs_ch_estimates_time[0][i]); maxval = max(maxval,-calibration->drs_ch_estimates_time[0][i]); } } int shift = log2_approx(maxval); for (int n=0; n<length; n+=4) { dmrs_corr = 0; //calculate dot product of primary_synch0_time and rxdata[ar][n] (ar=0..nb_ant_rx) and store the sum in temp[n]; for (int ar=0; ar<ru->nb_rx; ar++) { result = dot_product64(ru->dmrssync, (int16_t*) &ru->common.rxdata[ar][n], frame_parms->ofdm_symbol_size, shift); if (ru->state == RU_CHECK_SYNC) { result = dot_product64((int16_t*) &calibration->drs_ch_estimates_time[ar], (int16_t*) &ru->common.rxdata[ar][n], frame_parms->ofdm_symbol_size, shift); } dmrs_corr += abs64(result); } if (ru->dmrs_corr != NULL) ru->dmrs_corr[n] = dmrs_corr; // tmpi holds <synchi,rx0>+<synci,rx1>+...+<synchi,rx_{nbrx-1}> if (dmrs_corr>maxlev0) { maxlev0 = dmrs_corr; maxpos0 = n; } avg0 += dmrs_corr; } avg0/=(length/4); int dmrsoffset = frame_parms->samples_per_tti + (3*frame_parms->ofdm_symbol_size)+(3*frame_parms->nb_prefix_samples) + frame_parms->nb_prefix_samples0; if ((int64_t)maxlev0 > (10*avg0)) {*lev = maxlev0; *avg=avg0; return((length+maxpos0-dmrsoffset)%length);} return(-1); }