% clc; clear all; close all;
ray_factor=0.25;
% 發(fā)送的二進(jìn)制點(diǎn)數(shù)；
N=10000; m=10;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 下面的程序只設(shè)置五條多徑；
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%




% 發(fā)送的二進(jìn)制點(diǎn)數(shù)；
N=10000; 
% 初始是0101的代碼；
input_signal=ceil(rand(1,N)-0.5);
% 再轉(zhuǎn)化為+-1的雙極性碼；
input_signal=sign(input_signal-0.5);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 很關(guān)鍵的一點(diǎn)就是：
% 設(shè)置基帶信號(hào)的采樣點(diǎn)數(shù)，用于將來的延遲設(shè)置
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 模擬發(fā)送信號(hào)；一路二進(jìn)制比特信號(hào)被分成兩路sin和cos正交的信號(hào)，
% 這兩路信號(hào)是不會(huì)相互干擾的，兩路信號(hào)分別有延遲和噪聲；
for i=1:2:size(input_signal,2)-1
    channel_i((i+1)/2)=input_signal(i);
end;
for i=2:2:size(input_signal,2)
    channel_q((i)/2)=input_signal(i);
end;

% 轉(zhuǎn)化為發(fā)送信號(hào)的形式；
channel_i_i=symbol_sample(channel_i,m);
channel_q_q=symbol_sample(channel_q,m);

 snr_plot=-20:20;
 ber=[];
 
for snr=-20:20
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 經(jīng)過瑞利多徑信道后的結(jié)果
% 加噪聲；
sigma=sqrt(1/10^(snr/10));
channel_i_ray=Rayleigh_DuoJing...
    (channel_i_i,sigma,5,ray_factor,[0,1,2,3,4],[0,-1,-2,-3,-4]);
channel_q_ray=Rayleigh_DuoJing...
    (channel_q_q,sigma,5,ray_factor,[0,1,2,3,4],[0,-1,-2,-3,-4]);
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% % 加噪聲；
% sigma=sqrt(1/10^(snr/10));
% randn('state',0);
% channel_i_ray=channel_i_ray+sigma*randn(size(channel_i_i));
% channel_q_ray=channel_q_ray+sigma*randn(size(channel_q_q));
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% 以下是檢測(cè)部分；
matrix_4=[ones(m,1),ones(m,1),(-1)*ones(m,1),(-1)*ones(m,1);
          ones(m,1),(-1)*ones(m,1),ones(m,1),(-1)*ones(m,1)];

output_signal=zeros(2,size(input_signal,2)/2);

for i=1:size(input_signal,2)/2
    i_q=[channel_i_ray((i-1)*m+1:i*m),...
        channel_q_ray((i-1)*m+1:i*m)];
    temp_i_q=i_q*matrix_4;
    max_i_q=max(i_q*matrix_4);
    if temp_i_q(1)==max_i_q
       output_signal(:,i)=[1;1];
    elseif temp_i_q(2)==max_i_q
       output_signal(:,i)=[1;-1];
    elseif temp_i_q(3)==max_i_q
       output_signal(:,i)=[-1;1];
    elseif temp_i_q(4)==max_i_q
       output_signal(:,i)=[-1;-1];
    end;
end;

       end_out=[];% 最后輸出的比特信息；
   for i=1:size(input_signal,2)/2
       temp_out=output_signal(:,i)';
       end_out=[end_out,temp_out];
   end;
   
   xx=find(input_signal-end_out);
   x_len=length(xx);
   ber_temp=x_len/N;
   ber=[ber,ber_temp];
end;
figure;
semilogy(snr_plot,ber,'b^-'); hold on; grid on;