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