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srsLTE/lib/include/srsran/phy/sync/ssb.h

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/**
*
* \section COPYRIGHT
*
* Copyright 2013-2021 Software Radio Systems Limited
*
* By using this file, you agree to the terms and conditions set
* forth in the LICENSE file which can be found at the top level of
* the distribution.
*
*/
#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 <inttypes.h>
/**
* @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_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);
#endif // SRSRAN_SSB_H
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