162 lines
5.7 KiB
C
162 lines
5.7 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2015 Software Radio Systems Limited
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*
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* \section LICENSE
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*
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* This file is part of the srsLTE library.
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*
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* srsLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* srsLTE is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* A copy of the GNU Affero General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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/******************************************************************************
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* File: pss.h
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*
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* Description: Primary synchronization signal (PSS) generation and detection.
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*
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* The srslte_pss_synch_t object provides functions for fast
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* computation of the crosscorrelation between the PSS and received
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* signal and CFO estimation. Also, the function srslte_pss_synch_tperiodic()
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* is designed to be called periodically every subframe, taking
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* care of the correct data alignment with respect to the PSS sequence.
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*
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* The object is designed to work with signals sampled at 1.92 Mhz
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* centered at the carrier frequency. Thus, downsampling is required
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* if the signal is sampled at higher frequencies.
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*
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* Reference: 3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6.11.1
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*****************************************************************************/
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#ifndef PSS_
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#define PSS_
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#include <stdint.h>
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#include <stdbool.h>
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#include "srslte/config.h"
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#include "srslte/phy/common/phy_common.h"
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#include "srslte/phy/utils/convolution.h"
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#include "srslte/phy/utils/filter.h"
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#define CONVOLUTION_FFT
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#define SRSLTE_PSS_LEN 62
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#define SRSLTE_PSS_RE (6*12)
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/* PSS processing options */
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#define SRSLTE_PSS_ACCUMULATE_ABS // If enabled, accumulates the correlation absolute value on consecutive calls to srslte_pss_synch_find_pss
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#define SRSLTE_PSS_ABS_SQUARE // If enabled, compute abs square, otherwise computes absolute value only
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#define SRSLTE_PSS_RETURN_PSR // If enabled returns peak to side-lobe ratio, otherwise returns absolute peak value
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/* Low-level API */
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typedef struct SRSLTE_API {
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srslte_dft_plan_t dftp_input;
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#ifdef CONVOLUTION_FFT
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srslte_conv_fft_cc_t conv_fft;
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srslte_filt_cc_t filter;
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#endif
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int decimate;
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uint32_t max_frame_size;
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uint32_t max_fft_size;
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uint32_t frame_size;
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uint32_t N_id_2;
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uint32_t fft_size;
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cf_t *pss_signal_freq_full[3];
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cf_t *pss_signal_time[3];
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cf_t pss_signal_freq[3][SRSLTE_PSS_LEN]; // One sequence for each N_id_2
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cf_t *tmp_input;
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cf_t *conv_output;
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float *conv_output_abs;
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float ema_alpha;
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float *conv_output_avg;
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float peak_value;
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}srslte_pss_synch_t;
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typedef enum { PSS_TX, PSS_RX } pss_direction_t;
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/* Basic functionality */
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SRSLTE_API int srslte_pss_synch_init_fft(srslte_pss_synch_t *q,
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uint32_t frame_size,
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uint32_t fft_size);
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SRSLTE_API int srslte_pss_synch_init_fft_offset(srslte_pss_synch_t *q,
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uint32_t frame_size,
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uint32_t fft_size,
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int cfo_i);
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SRSLTE_API int srslte_pss_synch_init_fft_offset_decim(srslte_pss_synch_t *q,
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uint32_t frame_size,
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uint32_t fft_size,
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int cfo_i,
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int decimate);
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SRSLTE_API int srslte_pss_synch_resize(srslte_pss_synch_t *q, uint32_t frame_size,
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uint32_t fft_size,
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int offset);
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SRSLTE_API int srslte_pss_synch_init(srslte_pss_synch_t *q,
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uint32_t frame_size);
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SRSLTE_API void srslte_pss_synch_free(srslte_pss_synch_t *q);
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SRSLTE_API void srslte_pss_synch_reset(srslte_pss_synch_t *q);
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SRSLTE_API int srslte_pss_generate(cf_t *signal,
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uint32_t N_id_2);
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SRSLTE_API void srslte_pss_get_slot(cf_t *slot,
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cf_t *pss_signal,
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uint32_t nof_prb,
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srslte_cp_t cp);
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SRSLTE_API void srslte_pss_put_slot(cf_t *pss_signal,
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cf_t *slot,
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uint32_t nof_prb,
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srslte_cp_t cp);
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SRSLTE_API void srslte_pss_synch_set_ema_alpha(srslte_pss_synch_t *q,
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float alpha);
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SRSLTE_API int srslte_pss_synch_set_N_id_2(srslte_pss_synch_t *q,
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uint32_t N_id_2);
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SRSLTE_API int srslte_pss_synch_find_pss(srslte_pss_synch_t *q,
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cf_t *input,
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float *corr_peak_value);
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SRSLTE_API int srslte_pss_synch_chest(srslte_pss_synch_t *q,
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cf_t *input,
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cf_t ce[SRSLTE_PSS_LEN]);
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SRSLTE_API float srslte_pss_synch_cfo_compute(srslte_pss_synch_t* q,
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cf_t *pss_recv);
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#endif // PSS_
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