/* -*- 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_STATIC_H #define INCLUDED_DIGITAL_OFDM_EQUALIZER_STATIC_H #include <gnuradio/digital/api.h> #include <gnuradio/digital/constellation.h> #include <gnuradio/digital/ofdm_equalizer_base.h> namespace gr { namespace digital { /*! * \brief Very simple static equalizer for OFDM. * \ingroup ofdm_blk * \ingroup equalizers_blk * * \details * This is an extremely simple equalizer. It will only work for * high-SNR, very, very slowly changing channels. * * It simply divides the signal with the currently known channel * state. Whenever a pilot symbol comes around, it updates the * channel state on that particular carrier by dividing the * received symbol with the known pilot symbol. */ class DIGITAL_API ofdm_equalizer_static : public ofdm_equalizer_1d_pilots { public: typedef boost::shared_ptr<ofdm_equalizer_static> sptr; ofdm_equalizer_static( int fft_len, 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, bool input_is_shifted = true ); ~ofdm_equalizer_static(); /*! \brief Divide the input signal with the current channel state. * * Does the following (and nothing else): * - Divide every OFDM symbol with the current channel state * - If a pilot symbol is found, re-set the channel state by dividing the received * symbol with the known pilot symbol */ 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>()); /* * \param fft_len FFT length * \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 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! */ static sptr make( int fft_len, 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, bool input_is_shifted = true ); }; } /* namespace digital */ } /* namespace gr */ #endif /* INCLUDED_DIGITAL_OFDM_EQUALIZER_STATIC_H */