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/**
* 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_DMRS_SCH_H
#define SRSRAN_DMRS_SCH_H
#include "srsran/phy/ch_estimation/chest_dl.h"
#include "srsran/phy/common/phy_common_nr.h"
#include "srsran/phy/phch/phch_cfg_nr.h"
#include <stdint.h>
#define SRSRAN_DMRS_SCH_MAX_SYMBOLS 4
/**
* @brief Helper macro for counting the number of subcarriers taken by DMRS in a PRB.
*/
#define SRSRAN_DMRS_SCH_SC(CDM_GROUPS, DMRS_TYPE) \
(SRSRAN_MIN(SRSRAN_NRE, (CDM_GROUPS) * ((DMRS_TYPE) == srsran_dmrs_sch_type_1 ? 6 : 4)))
/**
* @brief PDSCH DMRS estimator object
*
* @note The DMRS PDSCH object has to be initialised and the carrier parameters needs to be set.
*
* @see srsran_dmrs_sch_init
* @see srsran_dmrs_sch_set_carrier
* @see srsran_dmrs_sch_free
* @see srsran_dmrs_sch_put_sf
* @see srsran_dmrs_sch_estimate
*/
typedef struct {
bool is_rx;
srsran_carrier_nr_t carrier;
srsran_interp_lin_t interpolator_type1; /// Type 1 DMRS: 1 pilot every 2 RE
srsran_interp_lin_t interpolator_type2; /// Type 2 DMRS: 2 consecutive pilots every 6 RE
uint32_t max_nof_prb;
cf_t* pilot_estimates; /// Pilots least squares estimates
cf_t* temp; /// Temporal data vector of size SRSRAN_NRE * carrier.nof_prb
float* filter; ///< Smoothing filter
} srsran_dmrs_sch_t;
/**
* @brief Computes the symbol indexes carrying DMRS and stores them in symbols_idx
* @param dmrs_cfg DMRS configuration
* @param grant PDSCH information provided by a DCI
* @param symbols_idx is the destination pointer where the symbols indexes are stored
* @return It returns the number of symbols if inputs are valid, otherwise, it returns SRSRAN_ERROR code.
*/
SRSRAN_API int srsran_dmrs_sch_get_symbols_idx(const srsran_dmrs_sch_cfg_t* dmrs_cfg,
const srsran_sch_grant_nr_t* grant,
uint32_t symbols_idx[SRSRAN_DMRS_SCH_MAX_SYMBOLS]);
/**
* @brief Computes the resource element pattern of resource elements reserved for DMRS
* @param cfg PDSCH DMRS configuration provided by upper layers
* @param[out] pattern Provides the RE pattern to fill
* @return SRSRAN_SUCCESS if computation is successful, SRSRAN_ERROR code otherwise
*/
SRSRAN_API int srsran_dmrs_sch_rvd_re_pattern(const srsran_dmrs_sch_cfg_t* cfg,
const srsran_sch_grant_nr_t* grant,
srsran_re_pattern_t* pattern);
/**
* @brief Calculates the number of resource elements taken by a PDSCH-DMRS for a given PDSCH transmission
* @param dmrs_cfg PDSCH-DMRS configuration
* @param grant PDSCH information provided by a DCI
* @return it returns the number of resource elements if the configuration is valid, otherwise it returns SRSRAN_ERROR
*/
SRSRAN_API int srsran_dmrs_sch_get_N_prb(const srsran_dmrs_sch_cfg_t* dmrs_cfg, const srsran_sch_grant_nr_t* grant);
/**
* @brief Stringifies the PDSCH DMRS configuration
*
* @param cfg PDSCH DMRS configuration
* @param msg Pointer to the destination array
* @param max_len Maximum number of characters to write
*
* @return It returns the number of characters written in the vector if no error occurs, otherwise it returns
* SRSRAN_ERROR code
*/
SRSRAN_API int srsran_dmrs_sch_cfg_to_str(const srsran_dmrs_sch_cfg_t* cfg, char* msg, uint32_t max_len);
/**
* @brief Initialises DMRS PDSCH object
*
* @param q DMRS PDSCH object
* @param is_rx indicates whether the object is used as receiver (in this case, it shall initialise as an estimator)
* @return it returns SRSRAN_ERROR code if an error occurs, otherwise it returns SRSRAN_SUCCESS
*/
SRSRAN_API int srsran_dmrs_sch_init(srsran_dmrs_sch_t* q, bool is_rx);
/**
* @brief Frees DMRS PDSCH object
*
* @param q DMRS PDSCH object
*/
SRSRAN_API void srsran_dmrs_sch_free(srsran_dmrs_sch_t* q);
/**
* @brief Sets the carrier configuration. if the PDSCH DMRS object is configured as UE, it will resize internal buffers
* and objects.
*
* @param q DMRS PDSCH object
* @param carrier Carrier configuration
*
* @return it returns SRSRAN_ERROR code if an error occurs, otherwise it returns SRSRAN_SUCCESS
*/
SRSRAN_API int srsran_dmrs_sch_set_carrier(srsran_dmrs_sch_t* q, const srsran_carrier_nr_t* carrier);
/**
* @brief Puts PDSCH DMRS into a given resource grid
*
* @param q DMRS PDSCH object
* @param slot_cfg Slot configuration
* @param pdsch_cfg PDSCH configuration provided by upper layers
* @param grant PDSCH information provided by a DCI
* @param sf_symbols Resource grid
*
* @return it returns SRSRAN_ERROR code if an error occurs, otherwise it returns SRSRAN_SUCCESS
*/
SRSRAN_API int srsran_dmrs_sch_put_sf(srsran_dmrs_sch_t* q,
const srsran_slot_cfg_t* slot_cfg,
const srsran_sch_cfg_nr_t* pdsch_cfg,
const srsran_sch_grant_nr_t* grant,
cf_t* sf_symbols);
/**
* @brief Estimates the channel for PDSCH from the DMRS
*
* @attention Current implementation supports only type1 PDSCH DMRS (1 pilot every 2 RE)
*
* @param q DMRS-PDSCH object
* @param slot Slot configuration
* @param cfg PDSCH configuration provided by upper layers
* @param grant PDSCH information provided by a DCI
* @param sf_symbols Received resource grid
* @param[out] ce Channel estimates
*
* @return it returns SRSRAN_ERROR code if an error occurs, otherwise it returns SRSRAN_SUCCESS
*/
SRSRAN_API int srsran_dmrs_sch_estimate(srsran_dmrs_sch_t* q,
const srsran_slot_cfg_t* slot,
const srsran_sch_cfg_nr_t* cfg,
const srsran_sch_grant_nr_t* grant,
const cf_t* sf_symbols,
srsran_chest_dl_res_t* chest_res);
#endif // SRSRAN_DMRS_SCH_H