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Diffstat (limited to 'gr-digital/include/digital_ofdm_equalizer_simpledfe.h')
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1 files changed, 0 insertions, 126 deletions
diff --git a/gr-digital/include/digital_ofdm_equalizer_simpledfe.h b/gr-digital/include/digital_ofdm_equalizer_simpledfe.h deleted file mode 100644 index 89b0b5cd6d..0000000000 --- a/gr-digital/include/digital_ofdm_equalizer_simpledfe.h +++ /dev/null @@ -1,126 +0,0 @@ -/* -*- c++ -*- */ -/* Copyright 2012 Free Software Foundation, Inc. - * - * This file is part of GNU Radio - * - * GNU Radio is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 3, or (at your option) - * any later version. - * - * GNU Radio 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 General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with GNU Radio; see the file COPYING. If not, write to - * the Free Software Foundation, Inc., 51 Franklin Street, - * Boston, MA 02110-1301, USA. - */ - -#ifndef INCLUDED_DIGITAL_OFDM_EQUALIZER_SIMPLEDFE_H -#define INCLUDED_DIGITAL_OFDM_EQUALIZER_SIMPLEDFE_H - -#include <digital/api.h> -#include <digital/constellation.h> -#include <digital_ofdm_equalizer_base.h> - -class digital_ofdm_equalizer_simpledfe; -typedef boost::shared_ptr<digital_ofdm_equalizer_simpledfe> digital_ofdm_equalizer_simpledfe_sptr; - -/* - * \param fft_len FFT length - * \param constellation The constellation object describing the modulation used - * on the subcarriers (e.g. QPSK). This is used to decode - * the individual symbols. - * \param occupied_carriers List of occupied carriers, see ofdm_carrier_allocator - * for a description. - * \param pilot_carriers Position of pilot symbols, see ofdm_carrier_allocator - * for a description. - * \param pilot_symbols Value of pilot symbols, see ofdm_carrier_allocator - * for a description. - * \param alpha Averaging coefficient (in a nutshell, if \f$H_{i,k}\f$ is the channel - * state for carrier i and symbol k, - * \f$H_{i,k+1} = \alpha H_{i,k} + (1 - \alpha) H_{i,k+1}\f$. Make this - * larger if there's more noise, but keep in mind that larger values - * of alpha mean slower response to channel changes). - * \param symbols_skipped Starting position within occupied_carriers and pilot_carriers. - * If the first symbol of the frame was removed (e.g. to decode the - * header), set this make sure the pilot symbols are correctly - * identified. - * \param input_is_shifted Set this to false if the input signal is not shifted, i.e. - * the first input items is on the DC carrier. - * Note that a lot of the OFDM receiver blocks operate on shifted - * signals! - */ -DIGITAL_API digital_ofdm_equalizer_simpledfe_sptr -digital_make_ofdm_equalizer_simpledfe( - int fft_len, - const gr::digital::constellation_sptr &constellation, - const std::vector<std::vector<int> > &occupied_carriers = std::vector<std::vector<int> >(), - const std::vector<std::vector<int> > &pilot_carriers = std::vector<std::vector<int> >(), - const std::vector<std::vector<gr_complex> > &pilot_symbols = std::vector<std::vector<gr_complex> >(), - int symbols_skipped = 0, - float alpha = 0.1, - bool input_is_shifted = true); - -/* \brief Simple decision feedback equalizer for OFDM. - * \ingroup ofdm_blk - * \ingroup eq_blk - * - * Equalizes an OFDM signal symbol by symbol using knowledge of the - * complex modulations symbols. - * For every symbol, the following steps are performed: - * - On every sub-carrier, decode the modulation symbol - * - Use the difference between the decoded symbol and the received symbol - * to update the channel state on this carrier - * - Whenever a pilot symbol is found, it uses the known pilot symbol to - * update the channel state. - * - * This equalizer makes a lot of assumptions: - * - The initial channel state is good enough to decode the first - * symbol without error (unless the first symbol only consists of pilot - * tones) - * - The channel changes only very slowly, such that the channel state - * from one symbol is enough to decode the next - * - SNR low enough that equalization will always suffice to correctly - * decode a symbol - * If these assumptions are not met, the most common error is that the - * channel state is estimated incorrectly during equalization; after that, - * all subsequent symbols will be completely wrong. - * - * Note that the equalized symbols are *exact points* on the constellation. - * This means soft information of the modulation symbols is lost after the - * equalization, which is suboptimal for channel codes that use soft decision. - * - */ -class DIGITAL_API digital_ofdm_equalizer_simpledfe : public digital_ofdm_equalizer_1d_pilots -{ - public: - digital_ofdm_equalizer_simpledfe( - int fft_len, - const gr::digital::constellation_sptr &constellation, - const std::vector<std::vector<int> > &occupied_carriers = std::vector<std::vector<int> >(), - const std::vector<std::vector<int> > &pilot_carriers = std::vector<std::vector<int> >(), - const std::vector<std::vector<gr_complex> > &pilot_symbols = std::vector<std::vector<gr_complex> >(), - int symbols_skipped = 0, - float alpha = 0.1, - bool input_is_shifted = true); - - ~digital_ofdm_equalizer_simpledfe(); - - void equalize(gr_complex *frame, - int n_sym, - const std::vector<gr_complex> &initial_taps = std::vector<gr_complex>(), - const std::vector<gr_tag_t> &tags = std::vector<gr_tag_t>()); - - private: - gr::digital::constellation_sptr d_constellation; - //! Averaging coefficient - float d_alpha; - -}; - -#endif /* INCLUDED_DIGITAL_OFDM_EQUALIZER_SIMPLEDFE_H */ - |