GNU Radio 3.7.1 C++ API
ofdm_carrier_allocator_cvc.h
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00001 /* -*- c++ -*- */
00002 /* 
00003  * Copyright 2013 Free Software Foundation, Inc.
00004  * 
00005  * This file is part of GNU Radio
00006  * 
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 3, or (at your option)
00010  * any later version.
00011  * 
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  * 
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 
00023 
00024 #ifndef INCLUDED_DIGITAL_OFDM_CARRIER_ALLOCATOR_CVC_H
00025 #define INCLUDED_DIGITAL_OFDM_CARRIER_ALLOCATOR_CVC_H
00026 
00027 #include <gnuradio/digital/api.h>
00028 #include <gnuradio/tagged_stream_block.h>
00029 
00030 namespace gr {
00031   namespace digital {
00032 
00033     /*!
00034      * \brief Create frequency domain OFDM symbols from complex values, add pilots.
00035      * \ingroup ofdm_blk
00036      *
00037      * \details
00038      * This block turns a stream of complex, scalar modulation symbols into vectors
00039      * which are the input for an IFFT in an OFDM transmitter. It also supports the
00040      * possibility of placing pilot symbols onto the carriers.
00041      *
00042      * The carriers can be allocated freely, if a carrier is not allocated, it is set
00043      * to zero. This allows doing OFDMA-style carrier allocations.
00044      *
00045      * Input: A tagged stream of complex scalars. The first item must have a tag
00046      *        containing the number of complex symbols in this frame.
00047      * Output: A tagged stream of complex vectors of length fft_len. This can directly
00048      *         be connected to an FFT block. Make sure to set this block to 'reverse'
00049      *         for the IFFT. If \p output_is_shifted is true, the FFT block must activate
00050      *         FFT shifting, otherwise, set shifting to false. If given, sync words are
00051      *         prepended to the output. Note that sync words are prepended verbatim,
00052      *         make sure they are shifted (or not).
00053      *
00054      * Carrier indexes are always such that index 0 is the DC carrier (note: you should
00055      * not allocate this carrier). The carriers below the DC carrier are either indexed
00056      * with negative numbers, or with indexes larger than \p fft_len/2. Index -1 and index
00057      * \p fft_len-1 both identify the carrier below the DC carrier.
00058      *
00059      */
00060     class DIGITAL_API ofdm_carrier_allocator_cvc : virtual public tagged_stream_block
00061     {
00062      public:
00063       typedef boost::shared_ptr<ofdm_carrier_allocator_cvc> sptr;
00064 
00065       virtual std::string len_tag_key() = 0;
00066       virtual const int fft_len() = 0;
00067       virtual std::vector<std::vector<int> > occupied_carriers() = 0;
00068 
00069       /*
00070        * \param fft_len FFT length, is also the maximum width of the OFDM symbols, the
00071        *                output vector size and maximum value for elements in
00072        *                \p occupied_carriers and \p pilot_carriers.
00073        * \param occupied_carriers A vector of vectors of indexes. Example: if
00074        *                          occupied_carriers = ((1, 2, 3), (1, 2, 4)), the first
00075        *                          three input symbols will be mapped to carriers 1, 2
00076        *                          and 3. After that, a new OFDM symbol is started. The next
00077        *                          three input symbols will be placed onto carriers 1, 2
00078        *                          and 4 of the second OFDM symbol. The allocation then
00079        *                          starts from the beginning.
00080        *                          Order matters! The first input symbol is always mapped
00081        *                          onto occupied_carriers[0][0].
00082        * \param pilot_carriers The position of the pilot symbols. Same as occupied_carriers,
00083        *                       but the actual symbols are taken from pilot_symbols instead
00084        *                       of the input stream.
00085        * \param pilot_symbols The pilot symbols which are placed onto the pilot carriers.
00086        *                      pilot_symbols[0][0] is placed onto the first OFDM symbol, on
00087        *                      carrier index pilot_carriers[0][0] etc.
00088        * \param sync_words OFDM symbols that are prepended to the OFDM frame (usually for
00089        *                   synchronisation purposes, e.g. OFDM symbols with every second
00090        *                   sub-carrier being idle). Is a vector of complex vectors of length
00091        *                   \p fft_len
00092        * \param len_tag_key The key of the tag identifying the length of the input packet.
00093        */
00094       static sptr make(
00095           int fft_len,
00096           const std::vector<std::vector<int> > &occupied_carriers,
00097           const std::vector<std::vector<int> > &pilot_carriers,
00098           const std::vector<std::vector<gr_complex> > &pilot_symbols,
00099           const std::vector<std::vector<gr_complex> > &sync_words,
00100           const std::string &len_tag_key = "packet_len",
00101           const bool output_is_shifted=true);
00102     };
00103 
00104   } // namespace digital
00105 } // namespace gr
00106 
00107 #endif /* INCLUDED_DIGITAL_OFDM_CARRIER_ALLOCATOR_CVC_H */
00108