/* * Copyright 2013-2020 Software Radio Systems Limited * * This file is part of srsLTE. * * srsLTE 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. * * srsLTE 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 SRSLTE_DMRS_PDCCH_H #define SRSLTE_DMRS_PDCCH_H #ifdef __cplusplus extern "C" { #endif #include "srslte/phy/common/phy_common_nr.h" #include "srslte/phy/resampling/resampler.h" #include "srslte/srslte.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 * @param cfg Configuration that includes Carrier, CORESET, Search Space and PDCCH candidate * @param slot_idx Slot index in the frame * @param sf_symbols is the resource grid where the DMRS resource elements will be written * @return SRSLTE_SUCCESS if the configurations are valid, otherwise it returns an SRSLTE_ERROR code */ SRSLTE_API int srslte_dmrs_pdcch_put(const srslte_nr_pdcch_cfg_t* cfg, uint32_t slot_idx, cf_t* sf_symbols); /** * @brief PDCCH DMRS channel estimator object * * @see srslte_dmrs_pdcch_estimator_init * @see srslte_dmrs_pdcch_estimator_free * @see srslte_dmrs_pdcch_estimator_estimate */ typedef struct SRSLTE_API { /// Current estimator carrier configuration srslte_nr_carrier_t carrier; /// Current estimator CORESET configuration srslte_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 srslte_resampler_fft_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[SRSLTE_CORESET_DURATION_MAX]; /// Channel estimates, size coreset_sz cf_t* ce; /// Stores latest slot index in frame uint32_t slot_idx; } srslte_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 * \attention Initialization is required every time the carrier and/or CORESET changes. No free is required between * initializations. * * @param q provides PDCCH DMRS estimator object * @param carrier provides the required carrier configuration for some estimation * @param coreset provides the required configuration for initialising the object * @return SRSLTE_SUCCESS if the configurations are valid, otherwise it returns an SRSLTE_ERROR code */ SRSLTE_API int srslte_dmrs_pdcch_estimator_init(srslte_dmrs_pdcch_estimator_t* q, const srslte_nr_carrier_t* carrier, const srslte_coreset_t* coreset); /** * @brief Deallocate all memory allocated by a given PDCCH DMRS estimator object * @param q provides PDCCH DMRS estimator object */ SRSLTE_API void srslte_dmrs_pdcch_estimator_free(srslte_dmrs_pdcch_estimator_t* q); /** * Estimates the PDCCH channel from the received PDCCH's DMRS. The DMRS are only transmitted in the REG where the * PDCCH is allocated. * * The most efficient way is estimating the overall CORESET independently whether there is data or not. Said so, the * output grid `estimates` shall be at least as big as the CORESET. * * This function is designed to be called prior to the PDCCH blind decoding and shall be called only once for every * CORESET. * * @param cfg Configuration that includes Carrier, CORESET and the Search Space * @param slot_idx Slot index in the frame * @param sf_symbols Received resource grid. * @param estimates CORESET Resource grid with the estimated channel * @return SRSLTE_SUCCESS if the configurations are valid, otherwise it returns an SRSLTE_ERROR code */ SRSLTE_API int srslte_dmrs_pdcch_estimate(srslte_dmrs_pdcch_estimator_t* q, uint32_t slot_idx, const cf_t* sf_symbols); /** * @brief PDSCH DMRS measurement results */ typedef struct SRSLTE_API { /// Linear reference signal received power (RSRP). Measure correlation float rsrp; /// Energy per resource element (EPRE) float epre; /// CFO Measure in Hz (only available for durations 2 and 3) float cfo_hz; /// Measure synchronization error in micro-seconds float sync_error_us; } srslte_dmrs_pdcch_measure_t; /** * @brief Performs PDCCH DMRS measurements of a given PDCCH candidate for an aggregation level * * @note The measurement is useful for determining whether there is a PDCCH transmission in the given candidate. * * @attention The provided aggregation level and candidate need to be according to the search space. * * @param q provides PDCCH DMRS estimator object * @param search_space provides the search space * @param slot_idx Slot index in the frame * @param aggregation_level Indicates the aggregation level of the candidate to examine * @param candidate Indicates the candidate index of the available * @param rnti Indicates the UE RNTI (only used for UE search space type) * @param measure Provides the structure for storing the channel estimate measurements * @return SRSLTE_SUCCESS if the configurations are valid, otherwise it returns an SRSLTE_ERROR code */ int srslte_dmrs_pdcch_get_measure(srslte_dmrs_pdcch_estimator_t* q, const srslte_search_space_t* search_space, uint32_t slot_idx, uint32_t aggregation_level, uint32_t candidate, uint16_t rnti, srslte_dmrs_pdcch_measure_t* measure); #ifdef __cplusplus } #endif #endif // SRSLTE_DMRS_PDCCH_H