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/tags.h>
#include <gnuradio/gr_complex.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;
      int d_carr_offset;

     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;
      //! Set the carrier offset in integer multiples
      void set_carrier_offset(int offset) { d_carr_offset = offset; };
      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 */