/** * Copyright 2013-2021 Software Radio Systems Limited * * This file is part of srsRAN. * * srsRAN 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. * * srsRAN 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/. * */ #ifndef SRSRAN_SSB_H #define SRSRAN_SSB_H #include "srsran/config.h" #include "srsran/phy/common/phy_common_nr.h" #include "srsran/phy/dft/dft.h" #include "srsran/phy/phch/pbch_nr.h" #include /** * @brief Default SSB maximum sampling rate */ #define SRSRAN_SSB_DEFAULT_MAX_SRATE_HZ 61.44e6 /** * @brief Default SSB minimum subcarrier spacing */ #define SRSRAN_SSB_DEFAULT_MIN_SCS srsran_subcarrier_spacing_15kHz /** * @brief Default beta value, used in case they are set to zero */ #define SRSRAN_SSB_DEFAULT_BETA 1.0f /** * @brief Maximum number of SSB positions in burst. Defined in TS 38.331 ServingCellConfigCommon, ssb-PositionsInBurst */ #define SRSRAN_SSB_NOF_CANDIDATES 64 /** * @brief Describes SSB object initialization arguments */ typedef struct SRSRAN_API { double max_srate_hz; ///< Maximum sampling rate in Hz, set to zero to use default srsran_subcarrier_spacing_t min_scs; ///< Minimum subcarrier spacing bool enable_search; ///< Enables PSS/SSS blind search bool enable_measure; ///< Enables PSS/SSS CSI measurements and frequency domain search bool enable_encode; ///< Enables PBCH Encoder bool enable_decode; ///< Enables PBCH Decoder bool disable_polar_simd; ///< Disables polar encoder/decoder SIMD acceleration float pbch_dmrs_thr; ///< NR-PBCH DMRS threshold for blind decoding, set to 0 for default } srsran_ssb_args_t; /** * @brief Describes SSB configuration arguments */ typedef struct SRSRAN_API { double srate_hz; ///< Current sampling rate in Hz double center_freq_hz; ///< Base-band center frequency in Hz double ssb_freq_hz; ///< SSB center frequency srsran_subcarrier_spacing_t scs; ///< SSB configured Subcarrier spacing srsran_ssb_patern_t pattern; ///< SSB pattern as defined in TS 38.313 section 4.1 Cell search srsran_duplex_mode_t duplex_mode; ///< Set to true if the spectrum is paired (FDD) uint32_t periodicity_ms; ///< SSB periodicity in ms float beta_pss; ///< PSS power allocation float beta_sss; ///< SSS power allocation float beta_pbch; ///< PBCH power allocation float beta_pbch_dmrs; ///< PBCH DMRS power allocation float scaling; ///< IFFT scaling (used for modulation), set to 0 for default } srsran_ssb_cfg_t; /** * @brief Describes SSB object */ typedef struct SRSRAN_API { srsran_ssb_args_t args; ///< Stores initialization arguments srsran_ssb_cfg_t cfg; ///< Stores last configuration /// Sampling rate dependent parameters float scs_hz; ///< Subcarrier spacing in Hz uint32_t max_sf_sz; ///< Maximum subframe size at the specified sampling rate uint32_t max_symbol_sz; ///< Maximum symbol size given the minimum supported SCS and sampling rate uint32_t max_corr_sz; ///< Maximum correlation size uint32_t max_ssb_sz; ///< Maximum SSB size in samples at the configured sampling rate uint32_t sf_sz; ///< Current subframe size at the specified sampling rate uint32_t symbol_sz; ///< Current SSB symbol size (for the given base-band sampling rate) uint32_t corr_sz; ///< Correlation size uint32_t corr_window; ///< Correlation window length uint32_t ssb_sz; ///< SSB size in samples at the configured sampling rate int32_t f_offset; ///< Current SSB integer frequency offset (multiple of SCS) uint32_t cp_sz; ///< CP length for the given symbol size /// Other parameters uint32_t l_first[SRSRAN_SSB_NOF_CANDIDATES]; ///< Start symbol for each SSB candidate in half radio frame uint32_t Lmax; ///< Number of SSB candidates /// Internal Objects srsran_dft_plan_t ifft; ///< IFFT object for modulating the SSB srsran_dft_plan_t fft; ///< FFT object for demodulate the SSB. srsran_dft_plan_t fft_corr; ///< FFT for correlation srsran_dft_plan_t ifft_corr; ///< IFFT for correlation srsran_pbch_nr_t pbch; ///< PBCH encoder and decoder /// Frequency/Time domain temporal data cf_t* tmp_freq; ///< Temporal frequency domain buffer cf_t* tmp_time; ///< Temporal time domain buffer cf_t* tmp_corr; ///< Temporal correlation frequency domain buffer cf_t* sf_buffer; ///< subframe buffer cf_t* pss_seq[SRSRAN_NOF_NID_2_NR]; ///< Possible frequency domain PSS for find } srsran_ssb_t; /** * @brief Describes an SSB search result * @note if pbch.crc is true, SSB transmission is found and decoded. Otherwise, no SSB transmission has been decoded */ typedef struct { uint32_t N_id; ///< Most suitable physical cell identifier uint32_t t_offset; ///< Time offset in the input samples srsran_pbch_msg_nr_t pbch_msg; ///< Physical broadcast channel message of the most suitable SSB candidate srsran_csi_trs_measurements_t measurements; ///< Measurements } srsran_ssb_search_res_t; /** * @brief Initialises configures NR SSB with the given arguments * @param q SSB object * @param args NR PSS initialization arguments * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_init(srsran_ssb_t* q, const srsran_ssb_args_t* args); /** * @brief Frees NR SSB object * @param q SSB object */ SRSRAN_API void srsran_ssb_free(srsran_ssb_t* q); /** * @brief Sets SSB configuration with the current SSB configuration * @param q SSB object * @param cfg Current SSB configuration * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_set_cfg(srsran_ssb_t* q, const srsran_ssb_cfg_t* cfg); /** * @brief Decodes PBCH in the given time domain signal * @note It currently expects an input buffer of half radio frame * @param q SSB object * @param N_id Physical Cell Identifier * @param n_hf Number of hald radio frame, 0 or 1 * @param ssb_idx SSB candidate index * @param in Input baseband buffer * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_decode_pbch(srsran_ssb_t* q, uint32_t N_id, uint32_t n_hf, uint32_t ssb_idx, const cf_t* in, srsran_pbch_msg_nr_t* msg); /** * @brief Searches for an SSB transmission and decodes the PBCH message * @param q SSB object * @param in Input baseband buffer * @param nof_samples Number of samples available in the buffer * @param res SSB Search result * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_search(srsran_ssb_t* q, const cf_t* in, uint32_t nof_samples, srsran_ssb_search_res_t* res); /** * @brief Decides if the SSB object is configured and a given subframe is configured for SSB transmission * @param q SSB object * @param sf_idx Subframe index within the radio frame * @return true if the SSB object is configured and SSB is transmitted, false otherwise */ SRSRAN_API bool srsran_ssb_send(srsran_ssb_t* q, uint32_t sf_idx); /** * @brief Adds SSB to a given signal in time domain * @param q SSB object * @param N_id Physical Cell Identifier * @param msg NR PBCH message to transmit * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_add(srsran_ssb_t* q, uint32_t N_id, const srsran_pbch_msg_nr_t* msg, const cf_t* in, cf_t* out); /** * @brief Perform cell search and measurement * @note This function assumes the SSB transmission is aligned with the input base-band signal * @param q SSB object * @param in Base-band signal buffer * @param N_id Physical Cell Identifier of the most suitable cell identifier * @param meas SSB-based CSI measurement of the most suitable cell identifier * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_csi_search(srsran_ssb_t* q, const cf_t* in, uint32_t nof_samples, uint32_t* N_id, srsran_csi_trs_measurements_t* meas); /** * @brief Perform Channel State Information (CSI) measurement from the SSB * @param q SSB object * @param N_id Physical Cell Identifier * @param ssb_idx SSB candidate index * @param in Base-band signal * @param meas SSB-based CSI measurement * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_csi_measure(srsran_ssb_t* q, uint32_t N_id, uint32_t ssb_idx, const cf_t* in, srsran_csi_trs_measurements_t* meas); /** * @brief Find SSB signal in a given time domain subframe buffer * @param q SSB object * @param sf_buffer subframe buffer with 1ms worth of samples * @param N_id Physical cell identifier to find * @param meas Measurements performed on the found peak * @param pbch_msg PBCH decoded message * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_find(srsran_ssb_t* q, const cf_t* sf_buffer, uint32_t N_id, srsran_csi_trs_measurements_t* meas, srsran_pbch_msg_nr_t* pbch_msg); /** * @brief Track SSB by performing measurements and decoding PBCH * @param q SSB object * @param sf_buffer subframe buffer with 1ms worth of samples * @param N_id Physical cell identifier to find * @param ssb_idx SSB candidate index * @param n_hf Number of half frame * @param meas Measurements perform * @param pbch_msg PBCH decoded message * @return SRSRAN_SUCCESS if the parameters are valid, SRSRAN_ERROR code otherwise */ SRSRAN_API int srsran_ssb_track(srsran_ssb_t* q, const cf_t* sf_buffer, uint32_t N_id, uint32_t ssb_idx, uint32_t n_hf, srsran_csi_trs_measurements_t* meas, srsran_pbch_msg_nr_t* pbch_msg); /** * @brief Calculates the subframe index within the radio frame of a given SSB candidate for the SSB object * @param q SSB object * @param ssb_idx SSB candidate index * @param half_frame Indicates whether it is half frame * @return The subframe index */ SRSRAN_API uint32_t srsran_ssb_candidate_sf_idx(const srsran_ssb_t* q, uint32_t ssb_idx, bool half_frame); /** * @brief Calculates the SSB offset within the subframe of a given SSB candidate for the SSB object * @param q SSB object * @param ssb_idx SSB candidate index * @return The sample offset within the subframe */ SRSRAN_API uint32_t srsran_ssb_candidate_sf_offset(const srsran_ssb_t* q, uint32_t ssb_idx); SRSRAN_API uint32_t srsran_ssb_cfg_to_str(const srsran_ssb_cfg_t* cfg, char* str, uint32_t str_len); #endif // SRSRAN_SSB_H