【OFDM通信】基于块状导频的信道估计算法仿真含Matlab源码

1 简介

首先对OFDM系统中基于导频辅助的信道估计算法进行研究,为了降低复杂度,利用奇异值分解(SVD)给出一种低阶近似的信道估计器。仿真结果表明LMMSE算法利用信道相关特性增加了运算量,但可以获得较好的估计效果,其简化算法(SVD)的性能略有下降,且随着信噪比增大,会出现"地板效应"。

2 部分代码

function ray_chann=rayleighnew(nsamp,tstp,fd,counter)
%****************** variables *************************
% idata : input Ich data
% qdata : input Qch data
% iout : output Ich data
% qout : output Qch data
% ramp : Amplitude contaminated by fading
% rcos : Cosine value contaminated by fading
% rsin : Cosine value contaminated by fading
% nsamp : Number of samples to be simulated
% tstp : Minimum time resolution
% fd : maximum doppler frequency
% no : number of waves in order to generate fading
% counter : fading counter
% flat : flat fading or not
% (1->flat (only amplitude is fluctuated),0->nomal(phase and amplitude are fluctutated)
%******************************************************
no=25;
if fd ~= 0.0
ac0 = sqrt(1.0 ./ (2.0.*(no + 1))); % power normalized constant(ich)
as0 = sqrt(1.0 ./ (2.0.*no)); % power normalized constant(qch)
%ic0 = counter; % fading counter
pai = 3.14159265;
wm = 2.0.*pai.*fd;
n = 4.*no + 2;
ts = tstp;
wmts = wm.*ts;
paino = pai./no;
xc=zeros(1,nsamp);
xs=zeros(1,nsamp);
ic=[1:nsamp]+counter;
for nn = 1: no
cwn = cos( cos(2.0.*pai.*nn./n).*ic.*wmts );
xc = xc + cos(paino.*nn).*cwn;
xs = xs + sin(paino.*nn).*cwn;
end
cwmt = sqrt(2.0).*cos(ic.*wmts);
xc = (2.0.*xc + cwmt).*ac0;
xs = 2.0.*xs.*as0;
%ramp=sqrt(xc.^2+xs.^2);
%rcos=xc./ramp;
%rsin=xs./ramp;
ray_chann=xc+j*xs;
else
ray_chann=ones(1,nsamp);
end
% ************************end of file***********************************

3 仿真结果

4 参考文献

[1]丁敬校, 王可人, 陈小波. 基于块状导频的OFDM信道估计[J]. 信息技术, 2011(7):4.

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