mmsefinal.m

自己编写的mmse equalizer代码

%-------------------------------------------------------%
%Name:        simulate channel with MMSE 
%Function:    analyze the data stream to useful data
%Author:      Group 
%Create date: 2008-10-10
%-------------------------------------------------------%
clear all
close all;
train_time = 3;
buf_c = zeros(5,1);
for(ii = 1:train_time)
    train_bits = sign(rand(1,10)-0.5);
    r_train = linch(train_bits);
    r_corr = xcorr(r_train);
    r_coeff = r_corr(length(r_train):(length(r_train)+4));
    R = toeplitz(r_coeff);
    r_y = xcorr(train_bits,r_train);
    P=r_y(((length(r_y)+1)/2-4):((length(r_y)+1)/2));
    Cmmse = inv(R)*P';
    buf_c = buf_c + Cmmse;
end
Cmmse = buf_c/train_time;

test_time = 100;
N = 100000;
BER_buf = [];
for(ii = 1:test_time)
    bn = sign(rand(1,N)-0.5);%creat  a new data sequence
    rn = linch(bn);
    re = conv(rn,Cmmse);% filter the signal from the channel 
    bn_est = sign(re(5:N+4));%take away the wrong part caused by the delay of the filters and make decision
    errors = sum(abs(bn_est - bn)/2);
    BER = errors/N;
    BER_buf = [BER_buf BER];
end

target = zeros(1,length(BER_buf))+ 0.005;

figure(1)
n = 1:length(BER_buf);
plot(n,target,'r-.');
hold on;
plot(BER_buf,'x');
axis([1 test_time 0 0.01]);
legend('Target BER','Real BER');