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/*
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* Copyright 2013-2019 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_FADING_H
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#define SRSLTE_FADING_H
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#include <inttypes.h>
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#include <srslte/srslte.h>
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#define SRSLTE_CHANNEL_FADING_MAXTAPS 9
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typedef enum {
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srslte_channel_fading_model_none = 0,
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srslte_channel_fading_model_epa,
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srslte_channel_fading_model_eva,
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srslte_channel_fading_model_etu,
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} srslte_channel_fading_model_t;
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typedef struct {
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// Configuration parameters
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float srate; // Sampling rate: 1.92e6, 3.84e6, ..., 23.04e6, 30.72e6
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srslte_channel_fading_model_t model; // None, EPA, EVA, ETU
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float doppler; // Maximum doppler: 5, 70, 300
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// Internal tap parametrization
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uint32_t N; // FFT size
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uint32_t path_delay; // Path delay
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double coeff_w[SRSLTE_CHANNEL_FADING_MAXTAPS]; // Angular Speed, random
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double coeff_a[SRSLTE_CHANNEL_FADING_MAXTAPS]; // Modulation Coefficient
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double coeff_p[SRSLTE_CHANNEL_FADING_MAXTAPS]; // Initial phase, random
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// Utils
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srslte_dft_plan_t fft; // DFT to frequency domain
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srslte_dft_plan_t ifft; // DFT to time domain
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cf_t* temp; // Temporal buffer, length fft_size
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cf_t* h_freq; // Channel frequency response, length fft_size
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cf_t* y_freq; // Intermediate frequency domain buffer
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// State variables
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cf_t* state; // Length fft_size/2
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} srslte_channel_fading_t;
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#ifdef __cplusplus
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extern "C" {
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#endif
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SRSLTE_API int srslte_channel_fading_init(srslte_channel_fading_t* q, double srate, const char* model, uint32_t seed);
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SRSLTE_API void srslte_channel_fading_free(srslte_channel_fading_t* q);
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SRSLTE_API double srslte_channel_fading_execute(srslte_channel_fading_t* q,
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const cf_t* in,
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cf_t* out,
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uint32_t nof_samples,
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double init_time);
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#ifdef __cplusplus
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}
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#endif
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#endif // SRSLTE_FADING_H
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