qpskrun.m

qpsk发送端到接收端

% file c10_MCQPSKrun.m
% Software given here is to accompany the textbook: W.H. Tranter, 
% K.S. Shanmugan, T.S. Rappaport, and K.S. Kosbar, Principles of 
% Communication Systems Simulation with Wireless Applications, 
% Prentice Hall PTR, 2004.
%
function [BER_MC,Errors]=QPSKrun(N,Eb,No,ChanAtt,...
	TimingBias,TimingJitter,PhaseBias,PhaseJitter)
fs = 1e+6;       					    % sampling Rate (samples/second)
SymRate = 1e+5;  					    % symbol rate (symbols/second)
Ts = 1/fs;							    % sampling period
TSym = 1/SymRate;					    % symbol period
ChanBW = 4.99e+5;					    % bandwidth of channel (Hz)
MeanCarrierPhaseError = PhaseBias;		% mean of carrier phase		  
StdCarrierPhaseError = PhaseJitter;		% stdev of phese error    
MeanSymbolSyncError = TimingBias;		% mean of symbol sync error
StdSymbolSyncError = TimingJitter;		% stdev of symbol sync error
ChanGain = 10^(-ChanAtt/20);			% channel gain (linear units)
TxBitClock = Ts/2;						% transmitter bit clock
RxBitClock = Ts/2;						% reciever bit clock
BlockSize = 1000;
SamplesPerSymbol = 10;  
RxBitsI = zeros(1,BlockSize);
RxBitsQ = zeros(1,BlockSize);
Errors = 0;
SampPerSym = fs/SymRate;
NumberOfBlocks = floor(N/BlockSize);
RxNoiseStd = sqrt((10^((No-30)/10))*fs/2);		% stdev of noise
TxSigAmp = sqrt(10^((Eb-30)/10)*SymRate);	

h = sqrc(1,10,4,0.5);

for Block=1:NumberOfBlocks
    [TxI,SourceBitsI] = random_binary(BlockSize,1);
    [TxQ,SourceBitsQ] = random_binary(BlockSize,1);

    % Make a complex data stream of the I and Q bits.
    %
%     TxBits_temp = ((TxBitsI*2)-1)+(sqrt(-1)*((TxBitsQ*2)-1));
      TxBits_temp = TxI + (sqrt(-1)*TxQ);
      TxBits = upsamp(TxBits_temp,SamplesPerSymbol);    
%     for count =1:SamplesPerSymbol
%         TxBits_temp2(count,:) = TxBits_temp;
%     end
%      
%     TxBits = reshape(TxBits_temp2,1,BlockSize*SamplesPerSymbol);
        
    TxOutput = TxBits*TxSigAmp;
    
    Rx = conv(TxOutput,h);
    
%     t = 0:1:length(Rx)-1;						% time vector for plot
%     subplot(2,1,1);
%     stem(t,real(Rx),'.');				% plot h[n-10]
%     grid;
%     xlabel('Time');
%     ylabel('h[n-1]');  
    
    Rx=(ChanGain*Rx)+(RxNoiseStd*(randn(1,length(Rx))+sqrt(-1)*randn(1,length(Rx))));
     
    PhaseRotation = exp(sqrt(-1)*2*pi*...
           (MeanCarrierPhaseError+(randn(1,1)*StdCarrierPhaseError))/360);
    Rx=Rx*PhaseRotation;
    
    IntegratorOutput = conv (Rx,h);
    

%     subplot(2,1,2);
%     t = 0:1:length(IntegratorOutput)-1;						% time vector for plot
%     stem(t,real(IntegratorOutput),'.');			% plot conv of h[n-10] and h[n]
%     grid;
%     xlabel('Time');
%     ylabel('conv(h[n-1],h[n])');
%     
    for k=1:BlockSize
        m = 1+round(SamplesPerSymbol*(k+MeanSymbolSyncError+StdSymbolSyncError*randn(1,1)));
        if (m < length(IntegratorOutput))
           RxBitsI(k) = (1-sign(real(IntegratorOutput(m))))/2;
           RxBitsQ(k) = (1-sign(imag(IntegratorOutput(m))))/2;
        end
    end
    [C,Lags] = vxcorr(SourceBitsI(10:990),RxBitsI(10:990));
    [MaxC,LocMaxC] = max(C);
    BestLag = Lags(LocMaxC);
    
    if BestLag > 0
    SourceBitsI = SourceBitsI(BestLag+1:length(SourceBitsI));
    SourceBitsQ = SourceBitsQ(BestLag+1:length(SourceBitsQ));
    elseif BestLag < 0
        RxBitsI = RxBitsI(-BestLag+1:length(RxBitsI));
        RxBitsQ = RxBitsQ(-BestLag+1:length(RxBitsQ));
    end
    TotalBits = min(length(SourceBitsI),length(RxBitsI));
    TotalBits = TotalBits-20;
    SourceBitsI = SourceBitsI(10:TotalBits);
    SourceBitsQ = SourceBitsQ(10:TotalBits);
    RxBitsI = RxBitsI(10:TotalBits);
    RxBitsQ = RxBitsQ(10:TotalBits);
%
% Find the number of errors and the BER.
%
    Errors = Errors + sum(SourceBitsI ~= RxBitsI) + sum(SourceBitsQ ~= RxBitsQ);

end
%
% Find the number of errors and the BER.
%
BER_MC = Errors/(2*(NumberOfBlocks*length(SourceBitsQ)));

% End of function file.