Encryption/TotalChannel.m at master · yuqm18/Encryption · GitHub

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
classdef TotalChannel

    properties (GetAccess='public', SetAccess='public')
        SymbolRate           % time precision of analog wave
        SampleRate              % AD/DA sample rate

        ConvCode                % Convolutional Coding

        ModType                 % Modulation Type 'psk','qam'


    end

    methods
        function obj = TotalChannel(SymbolRate1,SampleRate1,ConvCode1)
            obj.SymbolRate = 2000;
            obj.SampleRate = 32000;
            obj.ConvCode = [];
            obj.ModType = [];
            if nargin >= 1
                obj.SymbolRate = SymbolRate1;
                if nargin >= 2
                    obj.SampleRate = SampleRate1;
                    if nargin >= 3
                        obj.ConvCode = ConvCode1;
                    end
                end
            end

        end

        function [ErrorRate,SPDgram] = Run(obj,DataIn,EbByN0)
            %N0 sigle side SPD of noise


            fs = obj.SampleRate;
            rs = obj.SymbolRate;
            alpha = 0.5;

            if ~isempty(obj.ConvCode)
                DataIn1 = obj.ConvCode.ConvEncoder(DataIn);
                M = obj.ConvCode.nm(1);
            else
                DataIn1 = DataIn;
                M = [];
            end

            [Vol,MVol,StdVol] = obj.LevelModulation(DataIn1,M);
            Tsymbol = (0:length(Vol)-1)'/rs;
            T0 = (length(Vol)+200)/rs;

            Tg = 50/rs;     % G(t) duration
            Ng = fs*Tg;
            freq = [0:ceil(Ng/2)-1,-floor(Ng/2):-1]'/Tg;

            G = sqrt((abs(freq)<=(1-alpha)*rs/2)+(abs(freq)/rs*2>1-alpha&abs(freq)/rs*2<1+alpha).*cos((abs(freq)/rs*2-1+alpha)*2*pi/8/alpha).^2);
            g = real(ifft(G));
%             timeg = [0:ceil(Ng/2)-1 -floor(Ng/2):-1]'/fs;
            g = circshift(g,round(Tg/2*fs))/sqrt(sum(abs(g).^2));
            Eb = sum(abs(g).^2)/fs...   % energy of g(t)
                *mean(abs(StdVol).^2)...    % average Level，equal prob.
                *length(Vol)/length(DataIn)/2;

            timew = (1:T0*fs)'/fs;
%             waveBBT = pulstran(timew,[Tsymbol,Vol],g,fs);   %transmitted wave on baseband

            waveBBT = zeros(T0*fs,1);
            waveBBT(((1:length(Vol))-1)*fs/rs+1) = Vol; % pulse train
            waveBBT = conv(waveBBT,g,'full');
            waveBBT(T0*fs+1:end) = [];
            plotc(waveBBT(1:fs/rs*20))

            SPDgram = [ [0:ceil(T0*fs/2)-1 -floor(T0*fs/2):-1]' abs(fft(waveBBT)).^2];

            waveT = real(waveBBT.*exp(2j*pi*1850*timew));

            noise = random('Normal',0,sqrt(Eb/EbByN0*fs/2),size(waveT));

            waveR = waveT+noise;
            waveBBR = 2*waveR.*exp(-2j*pi*1850*timew);
            g1 = ifft(fft(g)');
            waveMF = conv(waveBBR,g1,'full');

            plotc(waveMF(1:30*fs/rs))

            VolR = waveMF(length(g)+1:fs/rs:length(waveMF));
%             Vol0 = bin2gray(0:3,'psk',4);
%             Vol0 = exp(1j*(2*Vol0)/4*pi);
            est = -abs(VolR-StdVol).^2;
            if isempty(obj.ConvCode)
            [~,symbolR] = max(est,[],2);
            symbolR = symbolR-1;
            symbolR = de2bi(symbolR);
            symbolR = reshape(symbolR',[],1);
            else
                symbolR = obj.ConvCode.ConvDecoder(est);
            end
            symbolR = symbolR(1:length(DataIn));
            ErrorRate = mean(abs(symbolR-DataIn));
        end

        function [Vol, M,StdVol] = LevelModulation(obj,DataIn,varargin)
            if nargin<3 || isempty(varargin{1})
                M = max(ceil(log2(length(DataIn)/(5*obj.SymbolRate))),0)+1;
            else
                M = varargin{1};
            end
            if strcmp(obj.ModType,'psk')
                modtype = @pskmod;
            elseif strcmp(obj.ModType,'qam')
                modtype = @qammod;
            else
                modtype = @pskmod;
            end
            DataIn = [reshape(DataIn,[],1);zeros(mod(M-mod(length(DataIn),M),M),1)];
            Vol = reshape(DataIn,M,[])';
            Vol = bi2de(Vol);
            Vol = modtype(Vol,2^M);
            StdVol = modtype(0:2^M-1,2^M);

        end

    end


end