psk_berest.m

AWGN多径信道中的QPSK系统进行BER性能仿真

%File: psk_berest.m
function [peideal,pesystem]=psk_berest(xx,yy,enn0db,eb,tb,nbw)
%ebn0db is an array of Eb/N0 values in db(specified at the receiver input);
%tb is the bit duration and nbw is the noise BW
%xx is the reference (ideal)input ;
%
ebn0db = [1:2:14];
nx = length(xx);
%
%For comparision purposes, set the noise BW of the ideal
%receiver (integrate and dump) to be equal to rs/2.
%
nbwideal = 1/(2*tb);    %noise bandwidth
for m=1:length(ebn0db)
    peideal(m)=0.0;  pesystem(m)=0.0   %initialize
    %
    %Find n0 and the variance of the noise.
    %
    ebn0(m) = 10^(ebn0db(m)/10);     %dB to linear
    n0 = eb/ebn0(m);      %noise power
    sigma = sqrt(n0*nbw*2);   %variance
    sigma1 = sqrt(n0*nbwideal*2);   %variance of ideal
    % 
    %Multiply the input constellation/signal by a scale factor so
    %that input constellation and the constellations/signal at the
    %input to receive filter have the same ave power
    % a = sqrt(2*eb/(2*tb))
    %
    b = sqrt(2*eb/tb)/sqrt(sum(abs(xx).^2)/nx);
    d1 = b*abs(xx);
    d3 = abs(yy);
    peideal(m) = sum (q(d1/sigma1));
    pesystem(m) = sum (q(d3/sigma));
  end
peideal = peideal/nx;
pesystem = pesystem/nx;
%End of function file.