1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
|
/* -*- c++ -*- */
/*
* Copyright 2011 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_IMPL_MPSK_SNR_EST_H
#define INCLUDED_DIGITAL_IMPL_MPSK_SNR_EST_H
#include <digital_api.h>
#include <gr_sync_block.h>
enum snr_est_type_t {
SNR_EST_SIMPLE = 0, // Simple estimator (>= 7 dB)
SNR_EST_SKEW, // Skewness-base est (>= 5 dB)
SNR_EST_M2M4, // 2nd & 4th moment est (>= 1 dB)
SNR_EST_SVR // SVR-based est (>= 0dB)
};
/*!
* Parent class for SNR Estimators
*/
class DIGITAL_API digital_impl_mpsk_snr_est
{
protected:
double d_alpha, d_beta;
public:
digital_impl_mpsk_snr_est(double alpha);
virtual ~digital_impl_mpsk_snr_est();
//! Get the running-average coefficient
double alpha() const;
//! Set the running-average coefficient
void set_alpha(double alpha);
//! Update the current registers
virtual int update(int noutput_items,
gr_vector_const_void_star &input_items);
//! Use the register values to compute a new estimate
virtual double snr();
};
class DIGITAL_API digital_impl_mpsk_snr_est_simple :
public digital_impl_mpsk_snr_est
{
private:
double d_y1, d_y2;
public:
digital_impl_mpsk_snr_est_simple(double alpha);
~digital_impl_mpsk_snr_est_simple() {}
int update(int noutput_items,
gr_vector_const_void_star &input_items);
double snr();
};
class DIGITAL_API digital_impl_mpsk_snr_est_skew :
public digital_impl_mpsk_snr_est
{
private:
double d_y1, d_y2, d_y3;
public:
digital_impl_mpsk_snr_est_skew(double alpha);
~digital_impl_mpsk_snr_est_skew() {}
int update(int noutput_items,
gr_vector_const_void_star &input_items);
double snr();
};
class DIGITAL_API digital_impl_mpsk_snr_est_m2m4 :
public digital_impl_mpsk_snr_est
{
private:
double d_y1, d_y2;
public:
/*! \brief SNR Estimator using 2nd and 4th-order moments.
*
* An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th
* (M4) order moments. This estimator uses knowledge of the
* kurtosis of the signal (k_a) and noise (k_w) to make its
* estimation. We use Beaulieu's approximations here to M-PSK
* signals and AWGN channels such that k_a=1 and k_w=2. These
* approximations significantly reduce the complexity of the
* calculations (and computations) required.
*
* Reference:
* D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
* estimation techniques for the AWGN channel," IEEE
* Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
*/
digital_impl_mpsk_snr_est_m2m4(double alpha);
~digital_impl_mpsk_snr_est_m2m4() {}
int update(int noutput_items,
gr_vector_const_void_star &input_items);
double snr();
};
class DIGITAL_API digital_impl_snr_est_m2m4 :
public digital_impl_mpsk_snr_est
{
private:
double d_y1, d_y2;
double d_ka, d_kw;
public:
/*! \brief SNR Estimator using 2nd and 4th-order moments.
*
* An SNR estimator for M-PSK signals that uses 2nd (M2) and 4th
* (M4) order moments. This estimator uses knowledge of the
* kurtosis of the signal (k_a) and noise (k_w) to make its
* estimation. In this case, you can set your own estimations for
* k_a and k_w, the kurtosis of the signal and noise, to fit this
* estimation better to your signal and channel conditions.
*
* A word of warning: this estimator has not been fully tested or
* proved with any amount of rigor. The estimation for M4 in
* particular might be ignoring effectf of when k_a and k_w are
* different. Use this estimator with caution and a copy of the
* reference on hand.
*
* The digital_mpsk_snr_est_m2m4 assumes k_a and k_w to simplify
* the computations for M-PSK and AWGN channels. Use that estimator
* unless you have a way to guess or estimate these values here.
*
* Original paper:
* R. Matzner, "An SNR estimation algorithm for complex baseband
* signal using higher order statistics," Facta Universitatis
* (Nis), no. 6, pp. 41-52, 1993.
*
* Reference used in derivation:
* D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
* estimation techniques for the AWGN channel," IEEE
* Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
*/
digital_impl_snr_est_m2m4(double alpha, double ka, double kw);
~digital_impl_snr_est_m2m4() {}
int update(int noutput_items,
gr_vector_const_void_star &input_items);
double snr();
};
class DIGITAL_API digital_impl_mpsk_snr_est_svr :
public digital_impl_mpsk_snr_est
{
private:
double d_y1, d_y2;
public:
/*! \brief Signal-to-Variation Ratio SNR Estimator.
*
* This estimator actually comes from an SNR estimator for M-PSK
* signals in fading channels, but this implementation is
* specifically for AWGN channels. The math was simplified to
* assume a signal and noise kurtosis (k_a and k_w) for M-PSK
* signals in AWGN. These approximations significantly reduce the
* complexity of the calculations (and computations) required.
*
* Original paper:
* A. L. Brandao, L. B. Lopes, and D. C. McLernon, "In-service
* monitoring of multipath delay and cochannel interference for
* indoor mobile communication systems," Proc. IEEE
* Int. Conf. Communications, vol. 3, pp. 1458-1462, May 1994.
*
* Reference:
* D. R. Pauluzzi and N. C. Beaulieu, "A comparison of SNR
* estimation techniques for the AWGN channel," IEEE
* Trans. Communications, Vol. 48, No. 10, pp. 1681-1691, 2000.
*/
digital_impl_mpsk_snr_est_svr(double alpha);
~digital_impl_mpsk_snr_est_svr() {}
int update(int noutput_items,
gr_vector_const_void_star &input_items);
double snr();
};
#endif /* INCLUDED_DIGITAL_IMPL_MPSK_SNR_EST_H */
|
