www.gusucode.com > DS-cdma仿真matlab程序 > code8/cdma/final21_extra.m
%********************************************************************* % This program simulates a predetection selective combining % receiver for a Rayleigh fading channel % % AUTHOR: Wenbin Luo % DATE : 04/28/01 % % final21_extra.m % %******************************************************************** clear all; %close all; format long; %set up the threshold Vt Vt = 0; Plot_Pe = []; N = 16; x_num = 10000; plot_EbNo = -30:2:20; %-20:2:10; for EbNo = -30:2:20, %convert back from dB Eb_No = EbNo; %dB Eb_No = 10.^(Eb_No/10); %assume No = 2; No = 2; Eb = No * Eb_No; %calculate power p Tc = 1; Ts = N * Tc; p = Eb / Ts; %generate BPSK symbols randomly with value +1 or -1 x = bingen(x_num); x_original = x; x = sqrt(p)*x; %generate Rayleigh fading [env1,env2] = fade_diversity(length(x),0.5); %generate faded sequence x_fad1 = env1.*x'; x_fad1 = x_fad1'; x_fad2 = env2.*x'; x_fad2 = x_fad2'; %DS-SS modulate symbols with user code c = bingen(N); y_fad1 = ds_mod(c(:),x_fad1); y_fad2 = ds_mod(c(:),x_fad2); %scale by appropriate power factor %y = sqrt(p)*y; %add AWGN to signal y_fad1 = awgn(y_fad1,1); y_fad2 = awgn(y_fad2,1); %DS-SS demodulate symbols with user code x_de1 = ds_demod(c(:),y_fad1); x_de2 = ds_demod(c(:),y_fad2); %choose branch with larger BENR ind1 = find(abs(x_de1) >= abs(x_de2)); ind2 = find(abs(x_de1) < abs(x_de2)); x_de(ind1) = x_de1(ind1); x_de(ind2) = x_de2(ind2); %decision x_de(find(x_de < 0)) = -1; x_de(find(x_de >=0)) = 1; Pe = length(find(x_original - x_de))/x_num; Plot_Pe = [Plot_Pe Pe]; end %end for EbNo %display the calculated Pd and Pfa Plot_Pe %plot Pe versus Eb/No %subplot(2,1,1) semilogy(plot_EbNo,Plot_Pe,'ro-') xlabel('Eb/No (dB)') ylabel('BER') s=sprintf('BER versus Eb/No in Rayleigh fading and AWGN'); title(s); grid on;