GNU Radio Manual and C++ API Reference
3.9.1.0
The Free & Open Software Radio Ecosystem
ofdm_chanest_vcvc.h
Go to the documentation of this file.
1
/* -*- c++ -*- */
2
/*
3
* Copyright 2013 Free Software Foundation, Inc.
4
*
5
* This file is part of GNU Radio
6
*
7
* SPDX-License-Identifier: GPL-3.0-or-later
8
*
9
*/
10
11
#ifndef INCLUDED_DIGITAL_OFDM_CHANEST_VCVC_H
12
#define INCLUDED_DIGITAL_OFDM_CHANEST_VCVC_H
13
14
#include <
gnuradio/block.h
>
15
#include <
gnuradio/digital/api.h
>
16
17
namespace
gr
{
18
namespace
digital {
19
20
/*! Estimate channel and coarse frequency offset for OFDM from preambles
21
* \ingroup ofdm_blk
22
* \ingroup synchronizers_blk
23
*
24
* Input: OFDM symbols (in frequency domain). The first one (or two) symbols are expected
25
* to be synchronisation symbols, which are used to estimate the coarse freq offset
26
* and the initial equalizer taps (these symbols are removed from the stream).
27
* The following \p n_data_symbols are passed through unmodified (the actual
28
* equalisation must be done elsewhere). Output: The data symbols, without the
29
* synchronisation symbols. The first data symbol passed through has two tags:
30
* 'ofdm_sync_carr_offset' (integer), the coarse frequency offset as number of
31
* carriers, and 'ofdm_sync_eq_taps' (complex vector). Any tags attached to the
32
* synchronisation symbols are attached to the first data symbol. All other tags are
33
* propagated as expected.
34
*
35
* Note: The vector on ofdm_sync_eq_taps is already frequency-corrected, whereas
36
* the rest is not.
37
*
38
* This block assumes the frequency offset is even (i.e. an integer multiple of 2).
39
*
40
* [1] Schmidl, T.M. and Cox, D.C., "Robust frequency and timing synchronization
41
* for OFDM", Communications, IEEE Transactions on, 1997.
42
* [2] K.D. Kammeyer, "Nachrichtenuebertragung," Chapter. 16.3.2.
43
*/
44
class
DIGITAL_API
ofdm_chanest_vcvc
:
virtual
public
block
45
{
46
public
:
47
typedef
std::shared_ptr<ofdm_chanest_vcvc>
sptr
;
48
49
/*!
50
* \param sync_symbol1 First synchronisation symbol in the frequency domain.
51
* Its length must be the FFT length. For Schmidl & Cox
52
* synchronisation, every second sub-carrier has to be zero.
53
* \param sync_symbol2 Second synchronisation symbol in the frequency domain.
54
* Must be equal to the FFT length, or zero length if
55
* only one synchronisation symbol is used. Using this
56
* symbol is how synchronisation is described in [1].
57
* Leaving this empty forces us to interpolate the
58
* equalizer taps.
59
* If you are using an unusual sub-carrier configuration
60
* (e.g. because of OFDMA), this sync symbol is used to
61
* identify the active sub-carriers. If you only have
62
* one synchronisation symbol, set the active sub-carriers
63
* to a non-zero value in here, and set \p force_one_sync_symbol
64
* parameter to true.
65
* \param n_data_symbols The number of data symbols following each set of
66
* synchronisation symbols. Must be at least 1.
67
* \param eq_noise_red_len If non-zero, noise reduction for the equalizer
68
* taps is done according to [2]. In this case, it
69
* is the channel influence time in number of samples.
70
* A good value is usually the length of the cyclic prefix.
71
* \param max_carr_offset Limit the number of sub-carriers the frequency
72
* offset can maximally be. Leave this zero to try
73
* all possibilities.
74
* \param force_one_sync_symbol See \p sync_symbol2.
75
*/
76
static
sptr
make(
const
std::vector<gr_complex>& sync_symbol1,
77
const
std::vector<gr_complex>& sync_symbol2,
78
int
n_data_symbols,
79
int
eq_noise_red_len = 0,
80
int
max_carr_offset = -1,
81
bool
force_one_sync_symbol =
false
);
82
};
83
84
}
// namespace digital
85
}
// namespace gr
86
87
#endif
/* INCLUDED_DIGITAL_OFDM_CHANEST_VCVC_H */
block.h
gr::digital::ofdm_chanest_vcvc::sptr
std::shared_ptr< ofdm_chanest_vcvc > sptr
Definition:
ofdm_chanest_vcvc.h:47
DIGITAL_API
#define DIGITAL_API
Definition:
gr-digital/include/gnuradio/digital/api.h:18
gr::block
The abstract base class for all 'terminal' processing blocks.
Definition:
block.h:59
api.h
gr
GNU Radio logging wrapper for log4cpp library (C++ port of log4j)
Definition:
basic_block.h:29
gr::digital::ofdm_chanest_vcvc
Definition:
ofdm_chanest_vcvc.h:44
gr-digital
include
gnuradio
digital
ofdm_chanest_vcvc.h
Generated by
1.8.17