/** * * \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: sync.h * * Description: Time and frequency synchronization using the PSS and SSS signals. * * 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. * * Correlation peak is detected comparing the maximum at the output * of the correlator with a threshold. The comparison accepts two * modes: absolute value or peak-to-mean ratio, which are configured * with the functions sync_pss_det_absolute() and sync_pss_det_peakmean(). * * * Reference: 3GPP TS 36.211 version 10.0.0 Release 10 Sec. 6.11.1, 6.11.2 *****************************************************************************/ #ifndef SYNC_ #define SYNC_ #include #include #include "srslte/config.h" #include "srslte/phy/sync/pss.h" #include "srslte/phy/sync/sss.h" #include "srslte/phy/sync/cfo.h" #include "srslte/phy/sync/cp.h" #define SRSLTE_SYNC_FFT_SZ_MIN 64 #define SRSLTE_SYNC_FFT_SZ_MAX 2048 typedef enum {SSS_DIFF=0, SSS_PARTIAL_3=2, SSS_FULL=1} sss_alg_t; typedef struct SRSLTE_API { srslte_pss_t pss; srslte_pss_t pss_i[2]; srslte_sss_t sss; srslte_cp_synch_t cp_synch; cf_t *cfo_i_corr[2]; int decimate; float threshold; float peak_value; uint32_t N_id_2; uint32_t N_id_1; uint32_t sf_idx; uint32_t fft_size; uint32_t frame_size; uint32_t max_offset; uint32_t nof_symbols; uint32_t cp_len; float current_cfo_tol; sss_alg_t sss_alg; bool detect_cp; bool sss_en; srslte_cp_t cp; uint32_t m0; uint32_t m1; float m0_value; float m1_value; float M_norm_avg; float M_ext_avg; cf_t *temp; uint32_t max_frame_size; // variables for various CFO estimation methods bool cfo_cp_enable; bool cfo_pss_enable; bool cfo_i_enable; bool cfo_cp_is_set; bool cfo_pss_is_set; bool cfo_i_initiated; float cfo_cp_mean; float cfo_pss_mean; int cfo_i_value; float cfo_ema_alpha; srslte_cfo_t cfo_corr_frame; srslte_cfo_t cfo_corr_symbol; bool sss_channel_equalize; bool pss_filtering_enabled; cf_t sss_filt[SRSLTE_SYMBOL_SZ_MAX]; cf_t pss_filt[SRSLTE_SYMBOL_SZ_MAX]; }srslte_sync_t; typedef enum { SRSLTE_SYNC_FOUND = 1, SRSLTE_SYNC_FOUND_NOSPACE = 2, SRSLTE_SYNC_NOFOUND = 0, SRSLTE_SYNC_ERROR = -1 } srslte_sync_find_ret_t; SRSLTE_API int srslte_sync_init(srslte_sync_t *q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size); SRSLTE_API int srslte_sync_init_decim(srslte_sync_t *q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size, int decimate); SRSLTE_API void srslte_sync_free(srslte_sync_t *q); SRSLTE_API int srslte_sync_resize(srslte_sync_t *q, uint32_t frame_size, uint32_t max_offset, uint32_t fft_size); SRSLTE_API void srslte_sync_reset(srslte_sync_t *q); /* Finds a correlation peak in the input signal around position find_offset */ SRSLTE_API srslte_sync_find_ret_t srslte_sync_find(srslte_sync_t *q, const cf_t *input, uint32_t find_offset, uint32_t *peak_position); /* Estimates the CP length */ SRSLTE_API srslte_cp_t srslte_sync_detect_cp(srslte_sync_t *q, const cf_t *input, uint32_t peak_pos); /* Sets the threshold for peak comparison */ SRSLTE_API void srslte_sync_set_threshold(srslte_sync_t *q, float threshold); /* Gets the subframe idx (0 or 5) */ SRSLTE_API uint32_t srslte_sync_get_sf_idx(srslte_sync_t *q); /* Gets the peak value */ SRSLTE_API float srslte_sync_get_peak_value(srslte_sync_t *q); /* Choose SSS detection algorithm */ SRSLTE_API void srslte_sync_set_sss_algorithm(srslte_sync_t *q, sss_alg_t alg); /* Sets PSS exponential averaging alpha weight */ SRSLTE_API void srslte_sync_set_em_alpha(srslte_sync_t *q, float alpha); /* Sets the N_id_2 to search for */ SRSLTE_API int srslte_sync_set_N_id_2(srslte_sync_t *q, uint32_t N_id_2); /* Gets the Physical CellId from the last call to synch_run() */ SRSLTE_API int srslte_sync_get_cell_id(srslte_sync_t *q); /* Enables/disables filtering of the central PRBs before PSS CFO estimation or SSS correlation*/ SRSLTE_API void srslte_sync_set_pss_filt_enable(srslte_sync_t *q, bool enable); SRSLTE_API void srslte_sync_set_sss_eq_enable(srslte_sync_t *q, bool enable); /* Gets the CFO estimation from the last call to synch_run() */ SRSLTE_API float srslte_sync_get_cfo(srslte_sync_t *q); /* Resets internal CFO state */ SRSLTE_API void srslte_sync_cfo_reset(srslte_sync_t *q); /* Copies CFO internal state from another object to avoid long transients */ SRSLTE_API void srslte_sync_copy_cfo(srslte_sync_t *q, srslte_sync_t *src_obj); /* Enable different CFO estimation stages */ SRSLTE_API void srslte_sync_set_cfo_i_enable(srslte_sync_t *q, bool enable); SRSLTE_API void srslte_sync_set_cfo_cp_enable(srslte_sync_t *q, bool enable); SRSLTE_API void srslte_sync_set_cfo_pss_enable(srslte_sync_t *q, bool enable); /* Sets CFO correctors tolerance (in Hz) */ SRSLTE_API void srslte_sync_set_cfo_tol(srslte_sync_t *q, float tol); /* Sets the exponential moving average coefficient for CFO averaging */ SRSLTE_API void srslte_sync_set_cfo_ema_alpha(srslte_sync_t *q, float alpha); /* Gets the CP length estimation from the last call to synch_run() */ SRSLTE_API srslte_cp_t srslte_sync_get_cp(srslte_sync_t *q); /* Sets the CP length estimation (must do it if disabled) */ SRSLTE_API void srslte_sync_set_cp(srslte_sync_t *q, srslte_cp_t cp); /* Enables/Disables SSS detection */ SRSLTE_API void srslte_sync_sss_en(srslte_sync_t *q, bool enabled); SRSLTE_API srslte_pss_t* srslte_sync_get_cur_pss_obj(srslte_sync_t *q); SRSLTE_API bool srslte_sync_sss_detected(srslte_sync_t *q); /* Enables/Disables CP detection */ SRSLTE_API void srslte_sync_cp_en(srslte_sync_t *q, bool enabled); #endif // SYNC_