ofdm_equalizer_base.h

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/* -*- 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_BASE_H
#define INCLUDED_DIGITAL_OFDM_EQUALIZER_BASE_H

#include <gnuradio/digital/api.h>
#include <gnuradio/gr_complex.h>
#include <gnuradio/tags.h>
#include <boost/enable_shared_from_this.hpp>

namespace gr {
namespace digital {

/*!
 * \brief Base class for implementation details of frequency-domain OFDM equalizers.
 * \ingroup ofdm_blk
 * \ingroup equalizers_blk
 */
class DIGITAL_API ofdm_equalizer_base
    : public boost::enable_shared_from_this<ofdm_equalizer_base>
{
protected:
    int d_fft_len;

public:
    typedef boost::shared_ptr<ofdm_equalizer_base> sptr;

    ofdm_equalizer_base(int fft_len);
    virtual ~ofdm_equalizer_base();

    //! Reset the channel information state knowledge
    virtual void reset() = 0;
    //! Run the actual equalization
    virtual void
    equalize(gr_complex* frame,
             int n_sym,
             const std::vector<gr_complex>& initial_taps = std::vector<gr_complex>(),
             const std::vector<tag_t>& tags = std::vector<tag_t>()) = 0;
    //! Return the current channel state
    virtual void get_channel_state(std::vector<gr_complex>& taps) = 0;
    int fft_len() { return d_fft_len; };
    sptr base() { return shared_from_this(); };
};


/* \brief Base class for implementation details of 1-dimensional OFDM FDEs which use pilot
 * tones. \ingroup digital
 *
 */
class DIGITAL_API ofdm_equalizer_1d_pilots : public ofdm_equalizer_base
{
protected:
    //! If \p d_occupied_carriers[k][l] is true, symbol k, carrier l is carrying data.
    //  (this is a different format than occupied_carriers!)
    std::vector<bool> d_occupied_carriers;
    //! If \p d_pilot_carriers[k][l] is true, symbol k, carrier l is carrying data.
    //  (this is a different format than pilot_carriers!)
    std::vector<std::vector<bool>> d_pilot_carriers;
    //! If \p d_pilot_carriers[k][l] is true, d_pilot_symbols[k][l] is its tx'd value.
    //  (this is a different format than pilot_symbols!)
    std::vector<std::vector<gr_complex>> d_pilot_symbols;
    //! In case the frame doesn't begin with OFDM symbol 0, this is the index of the first
    //! symbol
    int d_symbols_skipped;
    //! The current position in the set of pilot symbols
    int d_pilot_carr_set;
    //! Vector of length d_fft_len saving the current channel state (on the occupied
    //! carriers)
    std::vector<gr_complex> d_channel_state;

public:
    typedef boost::shared_ptr<ofdm_equalizer_1d_pilots> sptr;

    ofdm_equalizer_1d_pilots(int fft_len,
                             const std::vector<std::vector<int>>& occupied_carriers,
                             const std::vector<std::vector<int>>& pilot_carriers,
                             const std::vector<std::vector<gr_complex>>& pilot_symbols,
                             int symbols_skipped,
                             bool input_is_shifted);
    ~ofdm_equalizer_1d_pilots();

    void reset();
    void get_channel_state(std::vector<gr_complex>& taps);
};

} /* namespace digital */
} /* namespace gr */

#endif /* INCLUDED_DIGITAL_OFDM_EQUALIZER_BASE_H */