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@ -40,11 +40,32 @@
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#include "srslte/utils/vector.h"
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#include "srslte/utils/convolution.h"
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#define CHEST_RS_AVERAGE_TIME 2
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#define CHEST_RS_AVERAGE_FREQ 3
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#define NOISE_POWER_METHOD 1 // 0: Difference between noisy received and noiseless; 1: power of empty subcarriers
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#define DEFAULT_FILTER_FREQ_LEN 11 // Must be odd
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#define DEFAULT_FILTER_TIME_LEN 3
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static void init_default_filters(srslte_chest_dl_t *q) {
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float f[DEFAULT_FILTER_FREQ_LEN];
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float t[DEFAULT_FILTER_TIME_LEN];
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for (int i=0;i<DEFAULT_FILTER_FREQ_LEN/2+1;i++) {
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f[i] = 1+i;
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f[DEFAULT_FILTER_FREQ_LEN-i-1] = 1+i;
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}
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float norm = srslte_vec_acc_ff(f, DEFAULT_FILTER_FREQ_LEN);
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srslte_vec_sc_prod_fff(f, 1.0/norm, f, DEFAULT_FILTER_FREQ_LEN);
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srslte_chest_dl_set_filter_freq(q, f, DEFAULT_FILTER_FREQ_LEN);
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for (int i=0;i<DEFAULT_FILTER_TIME_LEN/2+1;i++) {
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t[i] = 1+i;
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t[DEFAULT_FILTER_TIME_LEN-i-1] = 1+i;
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}
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norm = srslte_vec_acc_ff(t, DEFAULT_FILTER_TIME_LEN);
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srslte_vec_sc_prod_fff(t, 1.0/norm, t, DEFAULT_FILTER_TIME_LEN);
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srslte_chest_dl_set_filter_time(q, t, DEFAULT_FILTER_TIME_LEN);
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}
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/** 3GPP LTE Downlink channel estimator and equalizer.
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* Estimates the channel in the resource elements transmitting references and interpolates for the rest
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@ -69,42 +90,28 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
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goto clean_exit;
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}
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q->tmp_freqavg = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
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q->tmp_freqavg = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp));
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if (!q->tmp_freqavg) {
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perror("malloc");
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goto clean_exit;
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}
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q->tmp_noise = srslte_vec_malloc(sizeof(cf_t) * 2 * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
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q->tmp_noise = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_SF_LEN_RE(cell.nof_prb, cell.cp));
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if (!q->tmp_noise) {
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perror("malloc");
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goto clean_exit;
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}
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for (int i=0;i<SRSLTE_CHEST_MAX_FILTER_TIME_LEN;i++) {
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q->tmp_timeavg[i] = srslte_vec_malloc(sizeof(cf_t) * 2*cell.nof_prb);
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if (!q->tmp_timeavg[i]) {
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perror("malloc");
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goto clean_exit;
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}
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bzero(q->tmp_timeavg[i], sizeof(cf_t) * 2*cell.nof_prb);
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}
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q->tmp_timeavg_mult = srslte_vec_malloc(sizeof(cf_t) * 2*cell.nof_prb);
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q->tmp_timeavg_mult = srslte_vec_malloc(sizeof(cf_t) * 12*cell.nof_prb);
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if (!q->tmp_timeavg_mult) {
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perror("malloc");
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goto clean_exit;
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}
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for (int i=0;i<cell.nof_ports;i++) {
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q->pilot_estimates[i] = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
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q->pilot_estimates[i] = srslte_vec_malloc(2*sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
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if (!q->pilot_estimates[i]) {
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perror("malloc");
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goto clean_exit;
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}
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// FIXME: There's an invalid read during rsrp estimation for this buffer
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q->pilot_estimates_average[i] = srslte_vec_malloc(2 * sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
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if (!q->pilot_estimates_average[i]) {
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perror("malloc");
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goto clean_exit;
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}
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q->pilot_recv_signal[i] = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_NUM_SF(cell.nof_prb, i));
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if (!q->pilot_recv_signal[i]) {
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perror("malloc");
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@ -122,15 +129,7 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
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goto clean_exit;
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}
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/* Set default time/freq filters */
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//float f[3]={0.2, 0.6, 0.2};
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//srslte_chest_dl_set_filter_freq(q, f, 3);
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float f[9]={0.025, 0.075, 0.05, 0.15, 0.4, 0.15, 0.05, 0.075, 0.025};
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srslte_chest_dl_set_filter_freq(q, f, 9);
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//srslte_chest_dl_set_filter_time_ema(q, 0.8);
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init_default_filters(q);
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q->cell = cell;
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}
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@ -153,11 +152,6 @@ void srslte_chest_dl_free(srslte_chest_dl_t *q)
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if (q->tmp_noise) {
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free(q->tmp_noise);
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}
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for (int i=0;i<SRSLTE_CHEST_MAX_FILTER_TIME_LEN;i++) {
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if (q->tmp_timeavg[i]) {
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free(q->tmp_timeavg[i]);
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}
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}
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if (q->tmp_timeavg_mult) {
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free(q->tmp_timeavg_mult);
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}
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@ -168,9 +162,6 @@ void srslte_chest_dl_free(srslte_chest_dl_t *q)
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if (q->pilot_estimates[i]) {
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free(q->pilot_estimates[i]);
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}
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if (q->pilot_estimates_average[i]) {
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free(q->pilot_estimates_average[i]);
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}
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if (q->pilot_recv_signal[i]) {
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free(q->pilot_recv_signal[i]);
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}
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@ -209,14 +200,11 @@ int srslte_chest_dl_set_filter_time(srslte_chest_dl_t *q, float *filter, uint32_
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#if NOISE_POWER_METHOD==0
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/* Uses the difference between the averaged and non-averaged pilot estimates */
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static float estimate_noise_port(srslte_chest_dl_t *q, uint32_t port_id, cf_t *avg_pilots) {
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static float estimate_noise_port(srslte_chest_dl_t *q, cf_t *average, cf_t *ce, uint32_t len) {
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/* Use difference between averaged and noisy LS pilot estimates */
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srslte_vec_sub_ccc(avg_pilots, q->pilot_estimates[port_id],
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q->tmp_noise, SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));
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return srslte_vec_avg_power_cf(q->tmp_noise, SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));
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srslte_vec_sub_ccc(average, ce, q->tmp_noise, len);
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return srslte_vec_avg_power_cf(q->tmp_noise, len);
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}
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#endif
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@ -236,97 +224,52 @@ static float estimate_noise_port(srslte_chest_dl_t *q, cf_t *input) {
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}
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#endif
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#define pilot_est(idx) q->pilot_estimates[port_id][SRSLTE_REFSIGNAL_PILOT_IDX(idx,l,q->cell)]
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#define pilot_avg(idx) q->pilot_estimates_average[port_id][SRSLTE_REFSIGNAL_PILOT_IDX(idx,l,q->cell)]
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#define pilot_tmp(idx) q->tmp_freqavg[SRSLTE_REFSIGNAL_PILOT_IDX(idx,l,q->cell)]
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static void average_pilots(srslte_chest_dl_t *q, uint32_t port_id)
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static void average_estimates(srslte_chest_dl_t *q, cf_t *ce, uint32_t port_id)
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{
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int nref=2*q->cell.nof_prb;
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int nref=12*q->cell.nof_prb;
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uint32_t l, i;
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/* For each symbol with pilots in a slot */
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for (l=0;l<srslte_refsignal_cs_nof_symbols(port_id);l++) {
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for (l=0;l<SRSLTE_CP_NSYMB(q->cell.cp);l++) {
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if (q->filter_freq_len > 0) {
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/* Filter pilot estimates in frequency */
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srslte_conv_same_cf(&pilot_est(0), q->filter_freq, &pilot_tmp(0), nref, q->filter_freq_len);
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/* Adjust extremes using linear interpolation */
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pilot_tmp(0) += srslte_interp_linear_onesample(pilot_est(1), pilot_est(0))
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* q->filter_freq[q->filter_freq_len/2-1]*1.2;
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pilot_tmp(nref-1) += srslte_interp_linear_onesample(pilot_est(nref-2), pilot_est(nref-1))
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* q->filter_freq[q->filter_freq_len/2+1]*1.2;
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srslte_conv_same_cf(&ce[l*12*q->cell.nof_prb], q->filter_freq, &q->tmp_freqavg[l*12*q->cell.nof_prb], nref, q->filter_freq_len);
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} else {
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memcpy(&pilot_tmp(0), &pilot_est(0), nref * sizeof(cf_t));
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memcpy(&q->tmp_freqavg[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref * sizeof(cf_t));
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}
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}
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#if NOISE_POWER_METHOD==0
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q->noise_estimate[port_id] = estimate_noise_port(q, port_id, q->tmp_freqavg);
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q->noise_estimate[port_id] = estimate_noise_port(q, q->tmp_freqavg, ce,
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SRSLTE_SF_LEN_RE(q->cell.nof_prb, q->cell.cp));
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#endif
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//#define EMA_VEC
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/* Filter with Exponential moving average (IIR) */
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if (q->filter_time_ema > 0) {
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#ifdef EMA_VEC
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srslte_vec_ema_filter(&q->tmp_freqavg[0],
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&q->pilot_estimates_average[port_id][2*q->cell.nof_prb*srslte_refsignal_cs_nof_symbols(port_id)],
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&q->pilot_estimates_average[port_id][0],
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q->filter_time_ema,
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nref);
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for (l=1;l<srslte_refsignal_cs_nof_symbols(port_id);l++) {
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srslte_vec_ema_filter(&q->tmp_freqavg[2*q->cell.nof_prb*l],
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&q->pilot_estimates_average[port_id][2*q->cell.nof_prb*(l-1)],
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&q->pilot_estimates_average[port_id][2*q->cell.nof_prb*l],
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q->filter_time_ema,
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nref);
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}
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#else
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for (i=0;i<nref;i++) {
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l=0;
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pilot_avg(i) = SRSLTE_VEC_EMA(pilot_tmp(i), q->pilot_estimates_average[port_id][
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SRSLTE_REFSIGNAL_PILOT_IDX(i,srslte_refsignal_cs_nof_symbols(port_id),q->cell)], q->filter_time_ema);
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for (l=1;l<srslte_refsignal_cs_nof_symbols(port_id);l++) {
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pilot_avg(i) = SRSLTE_VEC_EMA(pilot_tmp(i), q->pilot_estimates_average[port_id][SRSLTE_REFSIGNAL_PILOT_IDX(i,l-1,q->cell)], q->filter_time_ema);
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}
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}
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#endif
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} else {
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/* Filter with FIR or don't filter */
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for (l=0;l<srslte_refsignal_cs_nof_symbols(port_id);l++) {
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for (l=0;l<SRSLTE_CP_NSYMB(q->cell.cp);l++) {
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/* Filter in time domain. */
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if (q->filter_time_len > 0) {
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/* Move last symbols */
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for (i=0;i<q->filter_time_len-1;i++) {
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memcpy(q->tmp_timeavg[i], q->tmp_timeavg[i+1], nref*sizeof(cf_t));
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}
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/* Save last symbol to buffer */
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memcpy(q->tmp_timeavg[q->filter_time_len-1], &pilot_tmp(0), nref*sizeof(cf_t));
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/* Multiply all symbols by filter and add them */
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if (l > 0) {
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bzero(&pilot_avg(0), nref * sizeof(cf_t));
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/* Multiply symbols by filter and add them */
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bzero(&ce[l*12*q->cell.nof_prb], nref * sizeof(cf_t));
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for (i=0;i<q->filter_time_len;i++) {
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srslte_vec_sc_prod_cfc(q->tmp_timeavg[i], q->filter_time[i], q->tmp_timeavg_mult, nref);
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srslte_vec_sum_ccc(q->tmp_timeavg_mult, &pilot_avg(0), &pilot_avg(0), nref);
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}
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if (l+i-q->filter_time_len/2 < SRSLTE_CP_NSYMB(q->cell.cp) && l+i-q->filter_time_len/2 > 0) {
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srslte_vec_sc_prod_cfc(&q->tmp_freqavg[(l+i-q->filter_time_len/2)*12*q->cell.nof_prb], q->filter_time[i], q->tmp_timeavg_mult, nref);
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srslte_vec_sum_ccc(q->tmp_timeavg_mult, &ce[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref);
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} else {
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memcpy(&pilot_avg(0), &pilot_tmp(0), nref * sizeof(cf_t));
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srslte_vec_sc_prod_cfc(&q->tmp_freqavg[l*12*q->cell.nof_prb], q->filter_time[i], q->tmp_timeavg_mult, nref);
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srslte_vec_sum_ccc(q->tmp_timeavg_mult, &ce[l*12*q->cell.nof_prb], &ce[l*12*q->cell.nof_prb], nref);
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}
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} else {
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memcpy(&pilot_avg(0), &pilot_tmp(0), nref * sizeof(cf_t));
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}
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} else {
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memcpy(&ce[l*12*q->cell.nof_prb], &q->tmp_freqavg[l*12*q->cell.nof_prb], nref * sizeof(cf_t));
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}
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}
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}
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#define cesymb(i) ce[SRSLTE_RE_IDX(q->cell.nof_prb,i,0)]
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static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *ce, uint32_t port_id)
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static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t *ce, uint32_t port_id)
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{
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/* interpolate the symbols with references in the freq domain */
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uint32_t l;
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@ -335,7 +278,7 @@ static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *ce, uint32_t port_id)
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/* Interpolate in the frequency domain */
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for (l=0;l<nsymbols;l++) {
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uint32_t fidx_offset = srslte_refsignal_cs_fidx(q->cell, l, port_id, 0);
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srslte_interp_linear_offset(&q->srslte_interp_lin, &pilot_avg(0),
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srslte_interp_linear_offset(&q->srslte_interp_lin, &pilot_estimates[2*q->cell.nof_prb*l],
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&ce[srslte_refsignal_cs_nsymbol(l,q->cell.cp, port_id) * q->cell.nof_prb * SRSLTE_NRE],
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fidx_offset, SRSLTE_NRE/2-fidx_offset);
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}
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@ -399,8 +342,13 @@ int srslte_chest_dl_estimate_port(srslte_chest_dl_t *q, cf_t *input, cf_t *ce, u
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srslte_vec_prod_conj_ccc(q->pilot_recv_signal[port_id], q->csr_signal.pilots[port_id/2][sf_idx],
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q->pilot_estimates[port_id], SRSLTE_REFSIGNAL_NUM_SF(q->cell.nof_prb, port_id));
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/* Average pilot estimates */
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average_pilots(q, port_id);
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if (ce != NULL) {
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/* Interpolate to create channel estimates for all resource grid */
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interpolate_pilots(q, q->pilot_estimates[port_id], ce, port_id);
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/* Average channel estimates */
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average_estimates(q, ce, port_id);
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}
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#if NOISE_POWER_METHOD==1
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q->noise_estimate[port_id] = estimate_noise_port(q, input);
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@ -413,11 +361,6 @@ int srslte_chest_dl_estimate_port(srslte_chest_dl_t *q, cf_t *input, cf_t *ce, u
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q->rssi[port_id] = srslte_chest_dl_rssi(q, input, port_id);
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}
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/* Interpolate to create channel estimates for all resource grid */
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if (ce != NULL) {
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interpolate_pilots(q, ce, port_id);
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}
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return 0;
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}
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ismagom
10 years ago