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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_PDCCH_H
#define SRSRAN_DMRS_PDCCH_H
#include "srsran/phy/common/phy_common_nr.h"
#include "srsran/phy/phch/dci_nr.h"
#include "srsran/phy/resampling/interp.h"
#include "srsran/phy/resampling/resampler.h"
/**
* @brief Puts in the resource grid the DeModulation Reference Signals for decoding PDCCH.
*
* @remark: Implemented as specified by TS 38.211 V15.8.0 Section 7.1.4.3
*
* @attention it expects sf_symbols to be size SRSRAN_SLOT_LEN_RE_NR(cfg->carrier.nof_prb)
*
* @param[in] carrier Provides carrier configuration
* @param[in] coreset Provides higher layer CORSET configuration
* @param[in] slot_cfg Provides DL slot configuration
* @param[in] dci_location Provides DCI location
* @param sf_symbols is the resource grid where the DMRS resource elements will be written
* @return SRSRAN_SUCCESS if the configurations are valid, otherwise it returns an SRSRAN_ERROR code
*/
SRSRAN_API int srsran_dmrs_pdcch_put(const srsran_carrier_nr_t* carrier,
const srsran_coreset_t* coreset,
const srsran_slot_cfg_t* slot_cfg,
const srsran_dci_location_t* dci_location,
cf_t* sf_symbols);
/**
* @brief PDCCH DMRS channel estimator object
*
* @see srsran_dmrs_pdcch_estimator_init
* @see srsran_dmrs_pdcch_estimator_free
* @see srsran_dmrs_pdcch_estimator_estimate
* @see srsran_dmrs_pdcch_estimator_measure
*/
typedef struct SRSRAN_API {
/// Current estimator carrier configuration
srsran_carrier_nr_t carrier;
/// Current estimator CORESET configuration
srsran_coreset_t coreset;
/// Stores the current CORESET bandwidth in PRB
uint32_t coreset_bw;
/// Stores the current CORESET size in RE
uint32_t coreset_sz;
/// Object for interpolating, it shall be initialised only once
srsran_interp_lin_t interpolator;
/// Pilots least square estimates, one vector for each possible symbol. Since there are one pilot every 4 sub-carriers
/// , each vector is three times the CORESEt band-width
cf_t* lse[SRSRAN_CORESET_DURATION_MAX];
/// Channel estimates, size coreset_sz
cf_t* ce;
/// Frequency domain smoothing filter
float* filter;
uint32_t filter_len;
} srsran_dmrs_pdcch_estimator_t;
/**
* @brief Initialises the PDCCH DMRS channel estimator from a given carrier and CORESET configuration
*
* \attention The initialization function expects the object being previously zeroed on its first call
* \attention Initialization is required every time the carrier and/or CORESET changes. No free is required between
* initializations.
*
* @param[in,out] q provides PDCCH DMRS estimator object
* @param[in] carrier Provides carrier configuration
* @param[in] coreset Provides higher layer CORSET configuration
* @return SRSRAN_SUCCESS if the configurations are valid, otherwise it returns an SRSRAN_ERROR code
*/
SRSRAN_API int srsran_dmrs_pdcch_estimator_init(srsran_dmrs_pdcch_estimator_t* q,
const srsran_carrier_nr_t* carrier,
const srsran_coreset_t* coreset);
/**
* @brief Deallocate all memory allocated by a given PDCCH DMRS estimator object
* @param q provides PDCCH DMRS estimator object
*/
SRSRAN_API void srsran_dmrs_pdcch_estimator_free(srsran_dmrs_pdcch_estimator_t* q);
/**
* @brief Estimates the configured CORESET channel from the received PDCCH's DMRS.
*
* This function is designed to be called prior to the PDCCH blind decoding and shall be called only once for every
* CORESET in every slot.
*
* The channel estimate measurements are performed at PDCCH candidate level through the function
* srsran_dmrs_pdcch_estimator_measure.
*
* @param[in,out] cfg Configuration that includes Carrier, CORESET and the Search Space
* @param[in] slot_cfg Slot index in the frame
* @param[in] sf_symbols Received resource grid.
* @return SRSRAN_SUCCESS if the configurations are valid, otherwise it returns an SRSRAN_ERROR code
*/
SRSRAN_API int
srsran_dmrs_pdcch_estimate(srsran_dmrs_pdcch_estimator_t* q, const srsran_slot_cfg_t* slot_cfg, const cf_t* sf_symbols);
/**
* @brief PDSCH DMRS measurement results
*
* @see srsran_dmrs_pdcch_estimator_measure
*/
typedef struct SRSRAN_API {
/// Linear reference signal received power (RSRP). Measure correlation
float rsrp;
float rsrp_dBfs;
/// Energy per resource element (EPRE)
float epre;
float epre_dBfs;
/// Normalized Correlation (RSRP / EPRE)
float norm_corr;
/// CFO Measure in Hz (only available for CORESET durations 2 and 3)
float cfo_hz;
/// Measure synchronization error in micro-seconds
float sync_error_us;
} srsran_dmrs_pdcch_measure_t;
/**
* @brief PDSCH DMRS Channel estimates structure
*
* @see srsran_dmrs_pdcch_get_ce
*/
typedef struct SRSRAN_API {
/// Channel estimates, subtract 1 DMRS for every 4 RE, a maximum of L=16 and 6 PRB per CCE
cf_t ce[SRSRAN_PDCCH_MAX_RE];
uint32_t nof_re;
float noise_var;
} srsran_dmrs_pdcch_ce_t;
/**
* @brief Performs PDCCH DMRS measurements of a given DCI location
*
* @note The measurement is useful for determining whether there is a PDCCH transmission in the given DCI location.
*
* @param[in] q provides PDCCH DMRS estimator object
* @param[in] dci_location provides the search space
* @param[in] location Provides the aggregation level and CCE resource
* @param[out] measure Provides the structure for storing the channel estimate measurements
* @return SRSRAN_SUCCESS if the configurations are valid, otherwise it returns an SRSRAN_ERROR code
*/
SRSRAN_API int srsran_dmrs_pdcch_get_measure(const srsran_dmrs_pdcch_estimator_t* q,
const srsran_dci_location_t* location,
srsran_dmrs_pdcch_measure_t* measure);
/**
* @brief Extracts PDCCH DMRS channel estimates of a given PDCCH candidate for an aggregation level
*
* @attention The provided aggregation level and candidate need to be according to the search space.
*
* @param[in] q provides PDCCH DMRS estimator object
* @param[in] location Provides the aggregation level and CCE resource
* @param[out] ce Provides the structure for storing the channel estimates
* @return SRSRAN_SUCCESS if the configurations are valid, otherwise it returns an SRSRAN_ERROR code
*/
SRSRAN_API int srsran_dmrs_pdcch_get_ce(const srsran_dmrs_pdcch_estimator_t* q,
const srsran_dci_location_t* location,
srsran_dmrs_pdcch_ce_t* ce);
#endif // SRSRAN_DMRS_PDCCH_H