srsRAN_4G/lib/include/srslte/phy/sync/pss.h

/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2015 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsLTE library.
 *
 * srsLTE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsLTE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */

/******************************************************************************
 *  File:         pss.h
 *
 *  Description:  Primary synchronization signal (PSS) generation and detection.
 *
 *                The srslte_pss_synch_t object provides functions for fast
 *                computation of the crosscorrelation between the PSS and received
 *                signal and CFO estimation. Also, the function srslte_pss_synch_tperiodic()
 *                is designed to be called periodically every subframe, taking
 *                care of the correct data alignment with respect to the PSS sequence.
 *
 *                The object is designed to work with signals sampled at 1.92 Mhz
 *                centered at the carrier frequency. Thus, downsampling is required
 *                if the signal is sampled at higher frequencies.
 *
 *  Reference:    3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6.11.1
 *****************************************************************************/

#ifndef PSS_
#define PSS_

#include <stdint.h>
#include <stdbool.h>

#include "srslte/config.h"
#include "srslte/phy/common/phy_common.h"
#include "srslte/phy/utils/convolution.h"
#include "srslte/phy/utils/filter.h"

#define CONVOLUTION_FFT

#define SRSLTE_PSS_LEN     62
#define SRSLTE_PSS_RE      (6*12)


/* PSS processing options */

#define SRSLTE_PSS_ACCUMULATE_ABS   // If enabled, accumulates the correlation absolute value on consecutive calls to srslte_pss_synch_find_pss

#define SRSLTE_PSS_ABS_SQUARE   // If enabled, compute abs square, otherwise computes absolute value only 

#define SRSLTE_PSS_RETURN_PSR  // If enabled returns peak to side-lobe ratio, otherwise returns absolute peak value


/* 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;

#endif
  int decimate;
  uint32_t frame_size;
  uint32_t N_id_2;
  uint32_t fft_size;
  cf_t *pss_signal_freq_full[3];
  
  cf_t *pss_signal_time[3];
  
  cf_t pss_signal_freq[3][SRSLTE_PSS_LEN]; // One sequence for each N_id_2
  cf_t *tmp_input;
  cf_t *conv_output;
  float *conv_output_abs;
  float ema_alpha; 
  float *conv_output_avg;
  float peak_value;
}srslte_pss_synch_t;

typedef enum { PSS_TX, PSS_RX } pss_direction_t;

/* Basic functionality */
SRSLTE_API int srslte_pss_synch_init_fft(srslte_pss_synch_t *q, 
                                         uint32_t frame_size, 
                                         uint32_t fft_size);

SRSLTE_API int srslte_pss_synch_init_fft_offset(srslte_pss_synch_t *q, 
                                                uint32_t frame_size, 
                                                uint32_t fft_size, 
                                                int cfo_i);

SRSLTE_API int srslte_pss_synch_init_fft_offset_decim(srslte_pss_synch_t *q,
                                                uint32_t frame_size, 
                                                uint32_t fft_size, 
                                                int cfo_i,
                                                int decimate);

SRSLTE_API int srslte_pss_synch_init(srslte_pss_synch_t *q, 
                                     uint32_t frame_size);

SRSLTE_API void srslte_pss_synch_free(srslte_pss_synch_t *q);

SRSLTE_API void srslte_pss_synch_reset(srslte_pss_synch_t *q); 

SRSLTE_API int srslte_pss_generate(cf_t *signal, 
                                   uint32_t N_id_2);

SRSLTE_API void srslte_pss_get_slot(cf_t *slot, 
                                    cf_t *pss_signal, 
                                    uint32_t nof_prb, 
                                    srslte_cp_t cp); 

SRSLTE_API void srslte_pss_put_slot(cf_t *pss_signal, 
                                    cf_t *slot, 
                                    uint32_t nof_prb, 
                                    srslte_cp_t cp);

SRSLTE_API void srslte_pss_synch_set_ema_alpha(srslte_pss_synch_t *q, 
                                               float alpha); 

SRSLTE_API int srslte_pss_synch_set_N_id_2(srslte_pss_synch_t *q, 
                                           uint32_t N_id_2);

SRSLTE_API int srslte_pss_synch_find_pss(srslte_pss_synch_t *q, 
                                         cf_t *input, 
                                         float *corr_peak_value);

SRSLTE_API int srslte_pss_synch_chest(srslte_pss_synch_t *q, 
                                      cf_t *input, 
                                      cf_t ce[SRSLTE_PSS_LEN]); 

SRSLTE_API float srslte_pss_synch_cfo_compute(srslte_pss_synch_t* q, 
                                              cf_t *pss_recv);

#endif // PSS_