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145 lines
4.8 KiB
C
145 lines
4.8 KiB
C
/**
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* Copyright 2013-2021 Software Radio Systems Limited
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*
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* This file is part of srsRAN.
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*
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* srsRAN 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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* srsRAN 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 srsran_pss_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 srsran_pss_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 SRSRAN_PSS_H
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#define SRSRAN_PSS_H
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#include <stdbool.h>
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#include <stdint.h>
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#include "srsran/config.h"
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#include "srsran/phy/common/phy_common.h"
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#include "srsran/phy/utils/convolution.h"
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#include "srsran/phy/utils/filter.h"
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#define CONVOLUTION_FFT
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#define SRSRAN_PSS_LEN 62
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#define SRSRAN_PSS_RE (6 * 12)
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/* PSS processing options */
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#define SRSRAN_PSS_ACCUMULATE_ABS // If enabled, accumulates the correlation absolute value on consecutive calls to
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// srsran_pss_find_pss
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#define SRSRAN_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 SRSRAN_API {
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#ifdef CONVOLUTION_FFT
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srsran_conv_fft_cc_t conv_fft;
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srsran_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_time_scale[3];
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cf_t pss_signal_freq[3][SRSRAN_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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bool filter_pss_enable;
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srsran_dft_plan_t dftp_input;
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srsran_dft_plan_t idftp_input;
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cf_t tmp_fft[SRSRAN_SYMBOL_SZ_MAX];
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cf_t tmp_fft2[SRSRAN_SYMBOL_SZ_MAX];
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cf_t tmp_ce[SRSRAN_PSS_LEN];
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bool chest_on_filter;
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} srsran_pss_t;
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typedef enum { PSS_TX, PSS_RX } pss_direction_t;
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/* Basic functionality */
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SRSRAN_API int srsran_pss_init_fft(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size);
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SRSRAN_API int srsran_pss_init_fft_offset(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i);
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SRSRAN_API int
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srsran_pss_init_fft_offset_decim(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int cfo_i, int decimate);
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SRSRAN_API int srsran_pss_resize(srsran_pss_t* q, uint32_t frame_size, uint32_t fft_size, int offset);
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SRSRAN_API int srsran_pss_init(srsran_pss_t* q, uint32_t frame_size);
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SRSRAN_API void srsran_pss_free(srsran_pss_t* q);
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SRSRAN_API void srsran_pss_reset(srsran_pss_t* q);
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SRSRAN_API void srsran_pss_filter_enable(srsran_pss_t* q, bool enable);
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SRSRAN_API void srsran_pss_sic(srsran_pss_t* q, cf_t* input);
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SRSRAN_API void srsran_pss_filter(srsran_pss_t* q, const cf_t* input, cf_t* output);
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SRSRAN_API int srsran_pss_generate(cf_t* signal, uint32_t N_id_2);
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SRSRAN_API void srsran_pss_get_slot(cf_t* slot, cf_t* pss_signal, uint32_t nof_prb, srsran_cp_t cp);
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SRSRAN_API void srsran_pss_put_slot(cf_t* pss_signal, cf_t* slot, uint32_t nof_prb, srsran_cp_t cp);
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SRSRAN_API void srsran_pss_set_ema_alpha(srsran_pss_t* q, float alpha);
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SRSRAN_API int srsran_pss_set_N_id_2(srsran_pss_t* q, uint32_t N_id_2);
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SRSRAN_API int srsran_pss_find_pss(srsran_pss_t* q, const cf_t* input, float* corr_peak_value);
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SRSRAN_API int srsran_pss_chest(srsran_pss_t* q, const cf_t* input, cf_t ce[SRSRAN_PSS_LEN]);
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SRSRAN_API float srsran_pss_cfo_compute(srsran_pss_t* q, const cf_t* pss_recv);
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#endif // SRSRAN_PSS_H
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