hh1.m

cdma 系统级仿真

windowlength=27;%窗口长度
beginsin=14;
sinlength=14;

period=80;
fftlength=17;%快速付利叶变换长度
nn6=1:windowlength;
line1=[(nn6-0)>=0];
line2=[(nn6-beginsin)>=0];
ditong(nn6)=line1-line2;
nn7=beginsin:windowlength;
rafa=linspace(0,0.5,sinlength);%生成14点线性向量，在0-0.5之间且包括0和0.5
ditong(nn7)=cos(rafa*pi);
ditong(period-windowlength+2:period)=fliplr(ditong(2:windowlength));
Hditong=ditong;
for nn8=1:fftlength*2      %作IDFT变换求得滤波器的时域特性
    nn9=1:length(Hditong);%80
    htemp(nn9)=Hditong(nn9).*cos(2*pi*(nn9-1)*(nn8-1)/period);
    hditong1(nn8)=sum(htemp(nn9));
end; 
fftline=12;
omiga=linspace(0,1,fftlength-fftline);
hintercept(1:fftline)=1;         %长度为34的升余弦窗
hintercept(fftline+1:fftlength)=0.5*(1+cos(omiga*pi));
hintercept(fftlength+1:length(hditong1))=0;
hditong2=hintercept.*hditong1;      %用升余弦窗截取
hditong3=hditong2(1:fftlength)/length(Hditong);    % 滤波器归一化 
hditong4=fliplr(hditong3);
hditong(1:fftlength)=hditong4(1:fftlength);
hditong(fftlength+1:fftlength*2-1)=hditong3(2:fftlength);%33点
%**************************************************************************
%*** 加多径 ***%
tao=[0 1 2 5 8];   %多径时延
multi_plus=[1 0.41 0.27 0.18 0.06];   %多径分量的幅度
% multi_plus=[1 0 0 0 0];   %相当于不加多径
newditong=zeros(length(tao),length(hditong)+max(tao));
for multindex=1:length(tao)
newditong(multindex,tao(multindex)+1:length(hditong)+tao(multindex))=multi_plus(multindex).*hditong(1,:);
end;
multiditong=sum(newditong);   %存在多径的信道冲激响应,sum(A)返回一行