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171 lines
6.7 KiB
C
171 lines
6.7 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 srsLTE.
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*
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* srsLTE 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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* srsLTE 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 SRSLTE_DMRS_SCH_H
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#define SRSLTE_DMRS_SCH_H
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#include "srslte/phy/ch_estimation/chest_dl.h"
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#include "srslte/phy/common/phy_common_nr.h"
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#include "srslte/phy/phch/phch_cfg_nr.h"
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#include <stdint.h>
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#define SRSLTE_DMRS_SCH_MAX_SYMBOLS 4
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/**
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* @brief Helper macro for counting the number of subcarriers taken by DMRS in a PRB.
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*/
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#define SRSLTE_DMRS_SCH_SC(CDM_GROUPS, DMRS_TYPE) \
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(SRSLTE_MIN(SRSLTE_NRE, (CDM_GROUPS) * ((DMRS_TYPE) == srslte_dmrs_sch_type_1 ? 6 : 4)))
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/**
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* @brief PDSCH DMRS estimator object
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*
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* @note The DMRS PDSCH object has to be initialised and the carrier parameters needs to be set.
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*
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* @see srslte_dmrs_sch_init
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* @see srslte_dmrs_sch_set_carrier
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* @see srslte_dmrs_sch_free
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* @see srslte_dmrs_sch_put_sf
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* @see srslte_dmrs_sch_estimate
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*/
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typedef struct {
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bool is_rx;
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srslte_carrier_nr_t carrier;
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srslte_interp_lin_t interpolator_type1; /// Type 1 DMRS: 1 pilot every 2 RE
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srslte_interp_lin_t interpolator_type2; /// Type 2 DMRS: 2 consecutive pilots every 6 RE
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uint32_t max_nof_prb;
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cf_t* pilot_estimates; /// Pilots least squares estimates
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cf_t* temp; /// Temporal data vector of size SRSLTE_NRE * carrier.nof_prb
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} srslte_dmrs_sch_t;
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/**
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* @brief Computes the symbol indexes carrying DMRS and stores them in symbols_idx
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* @param dmrs_cfg DMRS configuration
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* @param grant PDSCH information provided by a DCI
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* @param symbols_idx is the destination pointer where the symbols indexes are stored
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* @return It returns the number of symbols if inputs are valid, otherwise, it returns SRSLTE_ERROR code.
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*/
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SRSLTE_API int srslte_dmrs_sch_get_symbols_idx(const srslte_dmrs_sch_cfg_t* dmrs_cfg,
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const srslte_sch_grant_nr_t* grant,
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uint32_t symbols_idx[SRSLTE_DMRS_SCH_MAX_SYMBOLS]);
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/**
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* @brief Computes the sub-carrier indexes carrying DMRS
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*
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* @param cfg PDSCH DMRS configuration provided by upper layers
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* @param max_count is the number of sub-carriers to generate
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* @param sc_idx is the destination pointer where the sub-carrier indexes are stored
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*
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* @return It returns the number of sub-carriers if inputs are valid, otherwise, it returns SRSLTE_ERROR code.
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*/
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SRSLTE_API int srslte_dmrs_sch_get_sc_idx(const srslte_dmrs_sch_cfg_t* cfg, uint32_t max_count, uint32_t* sc_idx);
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/**
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* @brief Calculates the number of resource elements taken by a PDSCH-DMRS for a given PDSCH transmission
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* @param dmrs_cfg PDSCH-DMRS configuration
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* @param grant PDSCH information provided by a DCI
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* @return it returns the number of resource elements if the configuration is valid, otherwise it returns SRSLTE_ERROR
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*/
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SRSLTE_API int srslte_dmrs_sch_get_N_prb(const srslte_dmrs_sch_cfg_t* dmrs_cfg, const srslte_sch_grant_nr_t* grant);
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/**
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* @brief Stringifies the PDSCH DMRS configuration
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*
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* @param cfg PDSCH DMRS configuration
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* @param msg Pointer to the destination array
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* @param max_len Maximum number of characters to write
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*
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* @return It returns the number of characters written in the vector if no error occurs, otherwise it returns
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* SRSLTE_ERROR code
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*/
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SRSLTE_API int srslte_dmrs_sch_cfg_to_str(const srslte_dmrs_sch_cfg_t* cfg, char* msg, uint32_t max_len);
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/**
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* @brief Initialises DMRS PDSCH object
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*
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* @param q DMRS PDSCH object
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* @param is_rx indicates whether the object is used as receiver (in this case, it shall initialise as an estimator)
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* @return it returns SRSLTE_ERROR code if an error occurs, otherwise it returns SRSLTE_SUCCESS
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*/
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SRSLTE_API int srslte_dmrs_sch_init(srslte_dmrs_sch_t* q, bool is_rx);
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/**
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* @brief Frees DMRS PDSCH object
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*
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* @param q DMRS PDSCH object
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*/
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SRSLTE_API void srslte_dmrs_sch_free(srslte_dmrs_sch_t* q);
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/**
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* @brief Sets the carrier configuration. if the PDSCH DMRS object is configured as UE, it will resize internal buffers
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* and objects.
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*
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* @param q DMRS PDSCH object
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* @param carrier Carrier configuration
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*
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* @return it returns SRSLTE_ERROR code if an error occurs, otherwise it returns SRSLTE_SUCCESS
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*/
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SRSLTE_API int srslte_dmrs_sch_set_carrier(srslte_dmrs_sch_t* q, const srslte_carrier_nr_t* carrier);
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/**
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* @brief Puts PDSCH DMRS into a given resource grid
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*
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* @param q DMRS PDSCH object
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* @param slot_cfg Slot configuration
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* @param pdsch_cfg PDSCH configuration provided by upper layers
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* @param grant PDSCH information provided by a DCI
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* @param sf_symbols Resource grid
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*
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* @return it returns SRSLTE_ERROR code if an error occurs, otherwise it returns SRSLTE_SUCCESS
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*/
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SRSLTE_API int srslte_dmrs_sch_put_sf(srslte_dmrs_sch_t* q,
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const srslte_slot_cfg_t* slot_cfg,
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const srslte_sch_cfg_nr_t* pdsch_cfg,
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const srslte_sch_grant_nr_t* grant,
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cf_t* sf_symbols);
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/**
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* @brief Estimates the channel for PDSCH from the DMRS
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*
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* @attention Current implementation supports only type1 PDSCH DMRS (1 pilot every 2 RE)
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*
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* @param q DMRS-PDSCH object
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* @param slot_cfg Slot configuration
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* @param pdsch_cfg PDSCH configuration provided by upper layers
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* @param grant PDSCH information provided by a DCI
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* @param sf_symbols Received resource grid
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* @param[out] ce Channel estimates
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*
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* @return it returns SRSLTE_ERROR code if an error occurs, otherwise it returns SRSLTE_SUCCESS
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*/
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SRSLTE_API int srslte_dmrs_sch_estimate(srslte_dmrs_sch_t* q,
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const srslte_slot_cfg_t* slot_cfg,
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const srslte_sch_cfg_nr_t* pdsch_cfg,
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const srslte_sch_grant_nr_t* grant,
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const cf_t* sf_symbols,
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srslte_chest_dl_res_t* chest_res);
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#endif // SRSLTE_DMRS_SCH_H
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