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srsLTE
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Revert "Add noise reduction in PSS before estimating CFO" 

This reverts commit 0d7af88822.
This commit is contained in:
Ismael Gomez 2017-11-28 16:20:40 +01:00
parent 0d7af88822
commit 15a1304395
2 changed files with 68 additions and 94 deletions
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8
lib/include/srslte/phy/sync/pss.h
View File

@ -71,6 +71,8 @@
/* Low-level API */
typedef struct SRSLTE_API {
srslte_dft_plan_t dftp_input;
#ifdef CONVOLUTION_FFT
srslte_conv_fft_cc_t conv_fft;
srslte_filt_cc_t filter;
@ -95,12 +97,6 @@ typedef struct SRSLTE_API {
float ema_alpha;
float *conv_output_avg;
float peak_value;
srslte_dft_plan_t dftp_input;
srslte_dft_plan_t idftp_input;
cf_t tmp_fft[SRSLTE_SYMBOL_SZ_MAX];
cf_t yr[SRSLTE_PSS_LEN];
}srslte_pss_synch_t;
typedef enum { PSS_TX, PSS_RX } pss_direction_t;

34
lib/src/phy/sync/pss.c
View File

@ -137,13 +137,7 @@ int srslte_pss_synch_init_fft_offset_decim(srslte_pss_synch_t *q,
}
srslte_dft_plan_set_mirror(&q->dftp_input, true);
srslte_dft_plan_set_dc(&q->dftp_input, true);
if (srslte_dft_plan(&q->idftp_input, fft_size, SRSLTE_DFT_BACKWARD, SRSLTE_DFT_COMPLEX)) {
fprintf(stderr, "Error creating DFT plan \n");
goto clean_and_exit;
}
srslte_dft_plan_set_mirror(&q->idftp_input, true);
srslte_dft_plan_set_dc(&q->idftp_input, true);
srslte_dft_plan_set_norm(&q->dftp_input, true);
q->tmp_input = srslte_vec_malloc((buffer_size + frame_size*(q->decimate - 1)) * sizeof(cf_t));
if (!q->tmp_input) {
@ -320,7 +314,6 @@ void srslte_pss_synch_free(srslte_pss_synch_t *q) {
}
srslte_dft_plan_free(&q->dftp_input);
srslte_dft_plan_free(&q->idftp_input);
if(q->decimate > 1)
{
@ -567,34 +560,19 @@ int srslte_pss_synch_chest(srslte_pss_synch_t *q, cf_t *input, cf_t ce[SRSLTE_PS
return ret;
}
#define CLEAN_NOISE_DFT
//#define PSS_CFO_FREQ
/* Returns the CFO estimation given a PSS received sequence
*
* Source: An Efficient CFO Estimation Algorithm for the Downlink of 3GPP-LTE
* Feng Wang and Yu Zhu
*/
float srslte_pss_synch_cfo_compute(srslte_pss_synch_t* q, cf_t *pss_recv) {
cf_t y0, y1;
#ifdef PSS_CFO_FREQ
srslte_vec_prod_conj_ccc(&q->tmp_fft[q->fft_size/2-SRSLTE_PSS_LEN/2], q->pss_signal_freq[q->N_id_2], q->yr, SRSLTE_PSS_LEN);
y0 = srslte_vec_acc_cc(q->yr, SRSLTE_PSS_LEN/2);
y1 = srslte_vec_acc_cc(&q->yr[SRSLTE_PSS_LEN/2], SRSLTE_PSS_LEN/2);
#else
#ifdef CLEAN_NOISE_DFT
// Eliminate noise
srslte_dft_run_c(&q->dftp_input, pss_recv, q->tmp_fft);
bzero(q->tmp_fft, sizeof(cf_t)*(q->fft_size/2-SRSLTE_PSS_LEN/2));
bzero(&q->tmp_fft[q->fft_size/2+SRSLTE_PSS_LEN/2], sizeof(cf_t)*(q->fft_size/2-SRSLTE_PSS_LEN/2));
srslte_dft_run_c(&q->idftp_input, q->tmp_fft, pss_recv);
#endif
cf_t y0, y1, yr;
y0 = srslte_vec_dot_prod_ccc(q->pss_signal_time[q->N_id_2], pss_recv, q->fft_size/2);
y1 = srslte_vec_dot_prod_ccc(&q->pss_signal_time[q->N_id_2][q->fft_size/2], &pss_recv[q->fft_size/2], q->fft_size/2);
#endif
return carg(conjf(y0) * y1)/M_PI;
yr = conjf(y0) * y1;
return atan2f(__imag__ yr, __real__ yr) / M_PI;
}