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chest_dl: subframe averaging with previous

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master
Ismael Gomez 8 years ago
parent 58d955ea10
commit 82cfa01468
2 changed files with 94 additions and 78 deletions
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10
srslte/include/srslte/ch_estimation/chest_dl.h
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@ -63,6 +63,7 @@ typedef struct {
srslte_refsignal_cs_t csr_signal; srslte_refsignal_cs_t csr_signal;
cf_t *pilot_estimates; cf_t *pilot_estimates;
cf_t *pilot_estimates_average; cf_t *pilot_estimates_average;
cf_t *pilot_average_last;
cf_t *pilot_recv_signal; cf_t *pilot_recv_signal;
cf_t *tmp_noise; cf_t *tmp_noise;
@ -73,6 +74,9 @@ typedef struct {
uint32_t smooth_filter_len; uint32_t smooth_filter_len;
float smooth_filter[SRSLTE_CHEST_MAX_SMOOTH_FIL_LEN]; float smooth_filter[SRSLTE_CHEST_MAX_SMOOTH_FIL_LEN];
float time_ema_coeff;
bool average_subframe;
srslte_interp_linsrslte_vec_t srslte_interp_linvec; srslte_interp_linsrslte_vec_t srslte_interp_linvec;
srslte_interp_lin_t srslte_interp_lin; srslte_interp_lin_t srslte_interp_lin;
@ -102,6 +106,12 @@ SRSLTE_API void srslte_chest_dl_set_smooth_filter(srslte_chest_dl_t *q,
SRSLTE_API void srslte_chest_dl_set_smooth_filter3_coeff(srslte_chest_dl_t* q, SRSLTE_API void srslte_chest_dl_set_smooth_filter3_coeff(srslte_chest_dl_t* q,
float w); float w);
SRSLTE_API void srslte_chest_dl_set_time_ema_coeff(srslte_chest_dl_t *q,
float t);
SRSLTE_API void srslte_chest_dl_set_average_subframe(srslte_chest_dl_t *q,
bool enable);
SRSLTE_API void srslte_chest_dl_set_noise_alg(srslte_chest_dl_t *q, SRSLTE_API void srslte_chest_dl_set_noise_alg(srslte_chest_dl_t *q,
srslte_chest_dl_noise_alg_t noise_estimation_alg); srslte_chest_dl_noise_alg_t noise_estimation_alg);

162
srslte/lib/ch_estimation/chest_dl.c
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@ -39,32 +39,8 @@
#include "srslte/utils/vector.h" #include "srslte/utils/vector.h"
#include "srslte/utils/convolution.h" #include "srslte/utils/convolution.h"
#define AVERAGE_SUBFRAME #define DEFAULT_FILTER_LEN 3
#define DEFAULT_TIME_EMA_COEFF 0.9
//#define DEFAULT_FILTER_LEN 3
#ifdef DEFAULT_FILTER_LEN
static void set_default_filter(srslte_chest_dl_t *q, int filter_len) {
float fil[SRSLTE_CHEST_DL_MAX_SMOOTH_FIL_LEN];
for (int i=0;i<filter_len/2;i++) {
fil[i] = i+1;
fil[i+filter_len/2+1]=filter_len/2-i;
}
fil[filter_len/2]=filter_len/2+1;
float s=0;
for (int i=0;i<filter_len;i++) {
s+=fil[i];
}
for (int i=0;i<filter_len;i++) {
fil[i]/=s;
}
srslte_chest_dl_set_smooth_filter(q, fil, filter_len);
}
#endif
/** 3GPP LTE Downlink channel estimator and equalizer. /** 3GPP LTE Downlink channel estimator and equalizer.
* Estimates the channel in the resource elements transmitting references and interpolates for the rest * Estimates the channel in the resource elements transmitting references and interpolates for the rest
@ -104,6 +80,11 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
perror("malloc"); perror("malloc");
goto clean_exit; goto clean_exit;
} }
q->pilot_average_last = srslte_vec_malloc(sizeof(cf_t) * 2 * cell.nof_prb);
if (!q->pilot_average_last) {
perror("malloc");
goto clean_exit;
}
q->pilot_recv_signal = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb)); q->pilot_recv_signal = srslte_vec_malloc(sizeof(cf_t) * SRSLTE_REFSIGNAL_MAX_NUM_SF(cell.nof_prb));
if (!q->pilot_recv_signal) { if (!q->pilot_recv_signal) {
perror("malloc"); perror("malloc");
@ -127,7 +108,14 @@ int srslte_chest_dl_init(srslte_chest_dl_t *q, srslte_cell_t cell)
q->noise_alg = SRSLTE_NOISE_ALG_REFS; q->noise_alg = SRSLTE_NOISE_ALG_REFS;
q->smooth_filter_len = 3; q->time_ema_coeff = 1.0;
#ifdef DEFAULT_TIME_EMA_COEFF
q->time_ema_coeff = DEFAULT_TIME_EMA_COEFF;
#endif
q->average_subframe = true;
q->smooth_filter_len = DEFAULT_FILTER_LEN;
srslte_chest_dl_set_smooth_filter3_coeff(q, 0.1); srslte_chest_dl_set_smooth_filter3_coeff(q, 0.1);
q->cell = cell; q->cell = cell;
@ -158,6 +146,9 @@ void srslte_chest_dl_free(srslte_chest_dl_t *q)
if (q->pilot_estimates_average) { if (q->pilot_estimates_average) {
free(q->pilot_estimates_average); free(q->pilot_estimates_average);
} }
if (q->pilot_average_last) {
free(q->pilot_average_last);
}
if (q->pilot_recv_signal) { if (q->pilot_recv_signal) {
free(q->pilot_recv_signal); free(q->pilot_recv_signal);
} }
@ -233,52 +224,52 @@ static float estimate_noise_empty_sc(srslte_chest_dl_t *q, cf_t *input) {
static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t *ce, uint32_t port_id) static void interpolate_pilots(srslte_chest_dl_t *q, cf_t *pilot_estimates, cf_t *ce, uint32_t port_id)
{ {
#ifdef AVERAGE_SUBFRAME if (q->average_subframe) {
// Interpolate symbol 0 in the frequency domain // Interpolate symbol 0 in the frequency domain
uint32_t fidx_offset = srslte_refsignal_cs_fidx(q->cell, 0, port_id, 0); uint32_t fidx_offset = srslte_refsignal_cs_fidx(q->cell, 0, port_id, 0);
srslte_interp_linear_offset(&q->srslte_interp_lin, pilot_estimates, srslte_interp_linear_offset(&q->srslte_interp_lin, pilot_estimates,
&ce[srslte_refsignal_cs_nsymbol(0,q->cell.cp, port_id) * q->cell.nof_prb * SRSLTE_NRE], &ce[srslte_refsignal_cs_nsymbol(0,q->cell.cp, port_id) * q->cell.nof_prb * SRSLTE_NRE],
fidx_offset, SRSLTE_NRE/2-fidx_offset); fidx_offset, SRSLTE_NRE/2-fidx_offset);
// All channel estimates in the subframe are the same // All channel estimates in the subframe are the same
for (int l=1;l<2*SRSLTE_CP_NSYMB(q->cell.cp);l++) { for (int l=1;l<2*SRSLTE_CP_NSYMB(q->cell.cp);l++) {
memcpy(&ce[l*q->cell.nof_prb*SRSLTE_NRE], ce, q->cell.nof_prb*SRSLTE_NRE*sizeof(cf_t)); memcpy(&ce[l*q->cell.nof_prb*SRSLTE_NRE], ce, q->cell.nof_prb*SRSLTE_NRE*sizeof(cf_t));
} }
#else
uint32_t l=0;
uint32_t nsymbols = srslte_refsignal_cs_nof_symbols(port_id);
// Interpolate in the frequency domain
for (l=0;l<nsymbols;l++) {
uint32_t 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],
&ce[srslte_refsignal_cs_nsymbol(l,q->cell.cp, port_id) * q->cell.nof_prb * SRSLTE_NRE],
fidx_offset, SRSLTE_NRE/2-fidx_offset);
}
// Interpolate in the time domain between symbols
if (SRSLTE_CP_ISNORM(q->cell.cp)) {
if (nsymbols == 4) {
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(4), &cesymb(1), 4, 3);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(4), &cesymb(7), &cesymb(5), 3, 2);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(8), 4, 3);
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(11), &cesymb(12), 4, 2);
} else {
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(8), &cesymb(1), &cesymb(1), &cesymb(0), 7, 1);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(2), 7, 6);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(9), 7, 5);
}
} else { } else {
if (nsymbols == 4) { uint32_t l=0;
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(3), &cesymb(1), 3, 2); uint32_t nsymbols = srslte_refsignal_cs_nof_symbols(port_id);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(3), &cesymb(6), &cesymb(4), 3, 2);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(7), 3, 2); // Interpolate in the frequency domain
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(9), &cesymb(10), 3, 2); for (l=0;l<nsymbols;l++) {
uint32_t 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],
&ce[srslte_refsignal_cs_nsymbol(l,q->cell.cp, port_id) * q->cell.nof_prb * SRSLTE_NRE],
fidx_offset, SRSLTE_NRE/2-fidx_offset);
}
// Interpolate in the time domain between symbols
if (SRSLTE_CP_ISNORM(q->cell.cp)) {
if (nsymbols == 4) {
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(4), &cesymb(1), 4, 3);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(4), &cesymb(7), &cesymb(5), 3, 2);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(8), 4, 3);
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(11), &cesymb(11), &cesymb(12), 4, 2);
} else {
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(8), &cesymb(1), &cesymb(1), &cesymb(0), 7, 1);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(2), 7, 6);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(8), &cesymb(9), 7, 5);
}
} else { } else {
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(1), &cesymb(1), &cesymb(0), 6, 1); if (nsymbols == 4) {
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(2), 6, 5); srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(0), &cesymb(3), &cesymb(1), 3, 2);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(8), 6, 4); srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(3), &cesymb(6), &cesymb(4), 3, 2);
} srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(7), 3, 2);
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(6), &cesymb(9), &cesymb(9), &cesymb(10), 3, 2);
} else {
srslte_interp_linear_vector2(&q->srslte_interp_linvec, &cesymb(7), &cesymb(1), &cesymb(1), &cesymb(0), 6, 1);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(2), 6, 5);
srslte_interp_linear_vector(&q->srslte_interp_linvec, &cesymb(1), &cesymb(7), &cesymb(8), 6, 4);
}
}
} }
#endif
} }
void srslte_chest_dl_set_smooth_filter(srslte_chest_dl_t *q, float *filter, uint32_t filter_len) { void srslte_chest_dl_set_smooth_filter(srslte_chest_dl_t *q, float *filter, uint32_t filter_len) {
@ -307,21 +298,36 @@ void srslte_chest_dl_set_smooth_filter3_coeff(srslte_chest_dl_t* q, float w)
q->smooth_filter[1] = 1-2*w; q->smooth_filter[1] = 1-2*w;
} }
void srslte_chest_dl_set_time_ema_coeff(srslte_chest_dl_t *q, float t) {
if (t > 0.0 && t <= 1.0) {
q->time_ema_coeff = t;
}
}
void srslte_chest_dl_set_average_subframe(srslte_chest_dl_t *q, bool enable) {
q->average_subframe = enable;
}
static void average_pilots(srslte_chest_dl_t *q, cf_t *input, cf_t *output, uint32_t port_id) { static void average_pilots(srslte_chest_dl_t *q, cf_t *input, cf_t *output, uint32_t port_id) {
uint32_t nsymbols = srslte_refsignal_cs_nof_symbols(port_id); uint32_t nsymbols = srslte_refsignal_cs_nof_symbols(port_id);
uint32_t nref = 2*q->cell.nof_prb; uint32_t nref = 2*q->cell.nof_prb;
memcpy(output, input, nref*sizeof(cf_t)); memcpy(output, input, nref*sizeof(cf_t));
for (int l=1;l<nsymbols;l++) { for (int l=1;l<nsymbols;l++) {
#ifdef AVERAGE_SUBFRAME if (q->average_subframe) {
srslte_vec_sum_ccc(output, &input[l*nref], output, nref); srslte_vec_sum_ccc(output, &input[l*nref], output, nref);
#else } else {
srslte_conv_same_cf(&input[l*nref], q->smooth_filter, &output[l*nref], nref, q->smooth_filter_len); srslte_conv_same_cf(&input[l*nref], q->smooth_filter, &output[l*nref], nref, q->smooth_filter_len);
#endif }
}
if (q->average_subframe) {
srslte_vec_sc_prod_cfc(output, (float) q->time_ema_coeff/nsymbols, output, nref);
if (q->time_ema_coeff < 1.0) {
srslte_vec_sc_prod_cfc(q->pilot_average_last, 1-q->time_ema_coeff, q->pilot_average_last, nref);
srslte_vec_sum_ccc(q->pilot_average_last, output, output, nref);
memcpy(q->pilot_average_last, output, nref*sizeof(cf_t));
}
} }
#ifdef AVERAGE_SUBFRAME
srslte_vec_sc_prod_cfc(output, (float) 1.0/nsymbols, output, nref);
#endif
} }
float srslte_chest_dl_rssi(srslte_chest_dl_t *q, cf_t *input, uint32_t port_id) { float srslte_chest_dl_rssi(srslte_chest_dl_t *q, cf_t *input, uint32_t port_id) {

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