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227 lines
7.8 KiB
C
227 lines
7.8 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: sync.h
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*
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* Description: Time and frequency synchronization using the PSS and SSS signals.
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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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* Correlation peak is detected comparing the maximum at the output
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* of the correlator with a threshold. The comparison accepts two
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* modes: absolute value or peak-to-mean ratio, which are configured
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* with the functions sync_pss_det_absolute() and sync_pss_det_peakmean().
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*
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*
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* Reference: 3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6.11.1, 6.11.2
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*****************************************************************************/
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#ifndef SRSRAN_SYNC_H
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#define SRSRAN_SYNC_H
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#include <math.h>
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#include <stdbool.h>
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#include "srsran/config.h"
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#include "srsran/phy/sync/cfo.h"
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#include "srsran/phy/sync/cp.h"
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#include "srsran/phy/sync/pss.h"
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#include "srsran/phy/sync/sss.h"
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#define SRSRAN_SYNC_FFT_SZ_MIN 64
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#define SRSRAN_SYNC_FFT_SZ_MAX 2048
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typedef enum { SSS_DIFF = 0, SSS_PARTIAL_3 = 2, SSS_FULL = 1 } sss_alg_t;
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typedef struct SRSRAN_API {
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srsran_pss_t pss;
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srsran_pss_t pss_i[2];
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srsran_sss_t sss;
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srsran_cp_synch_t cp_synch;
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cf_t* cfo_i_corr[2];
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int decimate;
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float threshold;
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float peak_value;
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uint32_t N_id_2;
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uint32_t N_id_1;
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uint32_t sf_idx;
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uint32_t fft_size;
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uint32_t frame_size;
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uint32_t max_offset;
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uint32_t nof_symbols;
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uint32_t cp_len;
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float current_cfo_tol;
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sss_alg_t sss_alg;
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bool detect_cp;
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bool sss_en;
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srsran_cp_t cp;
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uint32_t m0;
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uint32_t m1;
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float m0_value;
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float m1_value;
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float M_norm_avg;
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float M_ext_avg;
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cf_t* temp;
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uint32_t max_frame_size;
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srsran_frame_type_t frame_type;
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bool detect_frame_type;
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// variables for various CFO estimation methods
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bool cfo_cp_enable;
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bool cfo_pss_enable;
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bool cfo_i_enable;
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bool cfo_cp_is_set;
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bool cfo_pss_is_set;
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bool cfo_i_initiated;
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float cfo_cp_mean;
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float cfo_pss;
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float cfo_pss_mean;
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int cfo_i_value;
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float cfo_ema_alpha;
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uint32_t cfo_cp_nsymbols;
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srsran_cfo_t cfo_corr_frame;
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srsran_cfo_t cfo_corr_symbol;
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bool sss_channel_equalize;
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bool pss_filtering_enabled;
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cf_t sss_filt[SRSRAN_SYMBOL_SZ_MAX];
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cf_t pss_filt[SRSRAN_SYMBOL_SZ_MAX];
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bool sss_generated;
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bool sss_detected;
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bool sss_available;
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float sss_corr;
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srsran_dft_plan_t idftp_sss;
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cf_t sss_recv[SRSRAN_SYMBOL_SZ_MAX];
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cf_t sss_signal[2][SRSRAN_SYMBOL_SZ_MAX];
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} srsran_sync_t;
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typedef enum {
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SRSRAN_SYNC_FOUND = 1,
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SRSRAN_SYNC_FOUND_NOSPACE = 2,
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SRSRAN_SYNC_NOFOUND = 0,
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SRSRAN_SYNC_ERROR = -1
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} srsran_sync_find_ret_t;
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SRSRAN_API int srsran_sync_init(srsran_sync_t* q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size);
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SRSRAN_API int
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srsran_sync_init_decim(srsran_sync_t* q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size, int decimate);
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SRSRAN_API void srsran_sync_free(srsran_sync_t* q);
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SRSRAN_API int srsran_sync_resize(srsran_sync_t* q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size);
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SRSRAN_API void srsran_sync_reset(srsran_sync_t* q);
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/* Finds a correlation peak in the input signal around position find_offset */
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SRSRAN_API srsran_sync_find_ret_t srsran_sync_find(srsran_sync_t* q,
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const cf_t* input,
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uint32_t find_offset,
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uint32_t* peak_position);
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/* Estimates the CP length */
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SRSRAN_API srsran_cp_t srsran_sync_detect_cp(srsran_sync_t* q, const cf_t* input, uint32_t peak_pos);
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/* Sets the threshold for peak comparison */
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SRSRAN_API void srsran_sync_set_threshold(srsran_sync_t* q, float threshold);
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/* Gets the subframe idx (0 or 5) */
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SRSRAN_API uint32_t srsran_sync_get_sf_idx(srsran_sync_t* q);
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/* Gets the peak value */
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SRSRAN_API float srsran_sync_get_peak_value(srsran_sync_t* q);
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/* Choose SSS detection algorithm */
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SRSRAN_API void srsran_sync_set_sss_algorithm(srsran_sync_t* q, sss_alg_t alg);
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/* Sets PSS exponential averaging alpha weight */
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SRSRAN_API void srsran_sync_set_em_alpha(srsran_sync_t* q, float alpha);
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/* Sets the N_id_2 to search for */
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SRSRAN_API int srsran_sync_set_N_id_2(srsran_sync_t* q, uint32_t N_id_2);
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SRSRAN_API int srsran_sync_set_N_id_1(srsran_sync_t* q, uint32_t N_id_1);
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/* Gets the Physical CellId from the last call to synch_run() */
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SRSRAN_API int srsran_sync_get_cell_id(srsran_sync_t* q);
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/* Enables/disables filtering of the central PRBs before PSS CFO estimation or SSS correlation*/
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SRSRAN_API void srsran_sync_set_pss_filt_enable(srsran_sync_t* q, bool enable);
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SRSRAN_API void srsran_sync_set_sss_eq_enable(srsran_sync_t* q, bool enable);
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/* Gets the CFO estimation from the last call to synch_run() */
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SRSRAN_API float srsran_sync_get_cfo(srsran_sync_t* q);
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/* Resets internal CFO state */
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SRSRAN_API void srsran_sync_cfo_reset(srsran_sync_t* q, float cfo_Hz);
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/* Copies CFO internal state from another object to avoid long transients */
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SRSRAN_API void srsran_sync_copy_cfo(srsran_sync_t* q, srsran_sync_t* src_obj);
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/* Enable different CFO estimation stages */
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SRSRAN_API void srsran_sync_set_cfo_i_enable(srsran_sync_t* q, bool enable);
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SRSRAN_API void srsran_sync_set_cfo_cp_enable(srsran_sync_t* q, bool enable, uint32_t nof_symbols);
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SRSRAN_API void srsran_sync_set_cfo_pss_enable(srsran_sync_t* q, bool enable);
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/* Sets CFO correctors tolerance (in Hz) */
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SRSRAN_API void srsran_sync_set_cfo_tol(srsran_sync_t* q, float tol);
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SRSRAN_API void srsran_sync_set_frame_type(srsran_sync_t* q, srsran_frame_type_t frame_type);
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/* Sets the exponential moving average coefficient for CFO averaging */
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SRSRAN_API void srsran_sync_set_cfo_ema_alpha(srsran_sync_t* q, float alpha);
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/* Gets the CP length estimation from the last call to synch_run() */
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SRSRAN_API srsran_cp_t srsran_sync_get_cp(srsran_sync_t* q);
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/* Sets the CP length estimation (must do it if disabled) */
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SRSRAN_API void srsran_sync_set_cp(srsran_sync_t* q, srsran_cp_t cp);
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/* Enables/Disables SSS detection */
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SRSRAN_API void srsran_sync_sss_en(srsran_sync_t* q, bool enabled);
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SRSRAN_API srsran_pss_t* srsran_sync_get_cur_pss_obj(srsran_sync_t* q);
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SRSRAN_API bool srsran_sync_sss_detected(srsran_sync_t* q);
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SRSRAN_API float srsran_sync_sss_correlation_peak(srsran_sync_t* q);
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SRSRAN_API bool srsran_sync_sss_available(srsran_sync_t* q);
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/* Enables/Disables CP detection */
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SRSRAN_API void srsran_sync_cp_en(srsran_sync_t* q, bool enabled);
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#endif // SRSRAN_SYNC_H
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