clear;

clc;

% 1.產(chǎn)生長(zhǎng)度為2000的0/1隨機(jī)序列，進(jìn)行BPSK調(diào)制，通過沖激響應(yīng)為h[1,0.8,0.3]的信道傳送，信道的高斯噪聲為20dB。

%用LMS算法進(jìn)行均衡輸出，均衡抽頭數(shù)為8，步長(zhǎng)為0.03，訓(xùn)練序列長(zhǎng)度為200。

% 2.繪制出星座圖顯示理想信號(hào)、均衡器輸入信號(hào)、均衡器輸出信號(hào)。

% 繪制出重復(fù)20次實(shí)驗(yàn)的瞬時(shí)誤差平方的統(tǒng)計(jì)平均收斂曲線。更改LMS算法步長(zhǎng)和抽頭個(gè)數(shù)，觀察瞬時(shí)均方收斂曲線有什么變化。

% 分析步長(zhǎng)因子和抽頭個(gè)數(shù)變化對(duì)LMS算法性能的影響。

N = 2000;M = 2;weight = 8;stepSize = 0.03;trainLen = 200;

g = randi(2,N,1) - 1;

cp = [];mod1 = [];f = 0.1 * 3 * pi;t = 0.19;

for n = 1 : length(g)

if g(n) == 0

A = zeros(1,20);

else

A = ones(1,20);

end

cp = [cp A];

c = cos(f*t);

mod1 = [mod1 c];

end

figure(1);

subplot(3,1,1);

plot(cp);

axis([0 200 -1 2]);

subplot(3,1,2);

plot(mod1);

axis([0 200 -2 2]);

cm = [];mod = [];

for n = 1 : length(g)

if g(n) == 0

c = cos(f*t + pi / 2);

else

c = -cos(f*t + pi / 2);

end

mod = [mod c];

end

subplot(3,1,3);

plot(mod);

axis([0 200 -2 2]);

figure(2);

subplot(4,1,1);

plot(mod);

axis([0 200 -2 2]);

mod = awgn(mod, 20);

subplot(4,1,2);

plot(mod);

axis([0 200 -2 2]);

%h = [1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0.599971];

%h = [0.734189,0,0,0,0,0,0,0,0,0,0,0,0,1,-0.406511,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0.295130];

h = [1,0.8,0.3];??%沖激響應(yīng)為h[1,0.8,0.3]的信道傳送

rxsig = conv(mod.',h);

subplot(4,1,3);

plot(rxsig);

axis([0 200 -2 2]);

eqlms = lineareq(weight,lms(stepSize));

eqlms.RefTap = 1;

y = equalize(eqlms,rxsig,mod(1:trainLen));

subplot(4,1,4);

plot(y);

axis([0 200 -2 2]);

hold on;

modmsg = pskmod(g,M);

filtmsg = conv(h,modmsg);

eq1.SigConst = pskmod([0,M - 1],M);

[symbolest,yd] = equalize(eqlms,filtmsg,modmsg(1:trainLen));

h = scatterplot(filtmsg,1,trainLen,'rx');

hold on;

scatterplot(symbolest,1,trainLen,'g.',h);

scatterplot(eq1.SigConst,1,0,'k*',h);

legend('Filtered signal','Equalized signal','Ideal sinal constellation');

hold off;

總結(jié)

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