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| author | Tom Rondeau <trondeau@vt.edu> | 2013-03-18 09:03:53 -0400 |
|---|---|---|
| committer | Tom Rondeau <trondeau@vt.edu> | 2013-03-18 09:03:53 -0400 |
| commit | 929a26c3542c3c12d5eafc1fb4d3eb9da4cca0bd (patch) | |
| tree | 0bdd2efc28d2a7b268017035069f0bc4a24cd797 /gr-digital/include/digital/ofdm_chanest_vcvc.h | |
| parent | f1d1e3e019c83334960e1dab2fba9cbc6ee59964 (diff) | |
| parent | cabdafcb55423b54b63b711c942d4438b6af1a65 (diff) | |
Merge branch 'next' of ssh://192.168.2.110/Users/git/gnuradio into next
Diffstat (limited to 'gr-digital/include/digital/ofdm_chanest_vcvc.h')
| -rw-r--r-- | gr-digital/include/digital/ofdm_chanest_vcvc.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/gr-digital/include/digital/ofdm_chanest_vcvc.h b/gr-digital/include/digital/ofdm_chanest_vcvc.h new file mode 100644 index 0000000000..0c29d630da --- /dev/null +++ b/gr-digital/include/digital/ofdm_chanest_vcvc.h @@ -0,0 +1,95 @@ +/* -*- c++ -*- */ +/* + * Copyright 2013 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_CHANEST_VCVC_H +#define INCLUDED_DIGITAL_OFDM_CHANEST_VCVC_H + +#include <digital/api.h> +#include <gr_block.h> + +namespace gr { + namespace digital { + + /*! + * \brief Estimate channel and coarse frequency offset for OFDM from preambles + * \ingroup ofdm_blk + * \ingroup sync_blk + * + * Input: OFDM symbols (in frequency domain). The first one (or two) symbols are expected + * to be synchronisation symbols, which are used to estimate the coarse freq offset + * and the initial equalizer taps (these symbols are removed from the stream). + * The following \p n_data_symbols are passed through unmodified (the actual equalisation + * must be done elsewhere). + * Output: The data symbols, without the synchronisation symbols. + * The first data symbol passed through has two tags: + * 'ofdm_sync_carr_offset' (integer), the coarse frequency offset as number of carriers, + * and 'ofdm_sync_eq_taps' (complex vector). + * Any tags attached to the synchronisation symbols are attached to the first data + * symbol. All other tags are propagated normally. + * + * This block assumes the frequency offset is even (i.e. an integer multiple of 2). + * + * [1] Schmidl, T.M. and Cox, D.C., "Robust frequency and timing synchronization for OFDM", + * Communications, IEEE Transactions on, 1997. + * [2] K.D. Kammeyer, "Nachrichtenuebertragung," Chapter. 16.3.2. + */ + class DIGITAL_API ofdm_chanest_vcvc : virtual public gr_block + { + public: + typedef boost::shared_ptr<ofdm_chanest_vcvc> sptr; + + /* + * \param sync_symbol1 First synchronisation symbol in the frequency domain. Its length must be + * the FFT length. For Schmidl & Cox synchronisation, every second sub-carrier + * has to be zero. + * \param sync_symbol2 Second synchronisation symbol in the frequency domain. Must be equal to + * the FFT length, or zero length if only one synchronisation symbol is used. + * Using this symbol is how synchronisation is described in [1]. Leaving this + * empty forces us to interpolate the equalizer taps. + * If you are using an unusual sub-carrier configuration (e.g. because of OFDMA), + * this sync symbol is used to identify the active sub-carriers. If you only + * have one synchronisation symbol, set the active sub-carriers to a non-zero + * value in here, and also set \p force_one_sync_symbol parameter to true. + * \param n_data_symbols The number of data symbols following each set of synchronisation symbols. + * Must be at least 1. + * \param eq_noise_red_len If non-zero, noise reduction for the equalizer taps is done according + * to [2]. In this case, it is the channel influence time in number of + * samples. A good value is usually the length of the cyclic prefix. + * \param max_carr_offset Limit the number of sub-carriers the frequency offset can maximally be. + * Leave this zero to try all possibilities. + * \param force_one_sync_symbol See \p sync_symbol2. + */ + static sptr make( + const std::vector<gr_complex> &sync_symbol1, + const std::vector<gr_complex> &sync_symbol2, + int n_data_symbols, + int eq_noise_red_len=0, + int max_carr_offset=-1, + bool force_one_sync_symbol=false + ); + }; + + } // namespace digital +} // namespace gr + +#endif /* INCLUDED_DIGITAL_OFDM_CHANEST_VCVC_H */ + |