OFDM系统系统有无cp与均衡的系统比较 MATLAB源码 -

function [s_out] = ofdm_mod_eq( s_in )
%% ofdm 调制，带均衡
%% 输入：二进制序列
%% 输出：ofdm调制后符号
%global CP_len;
global nSubC
global ifft_len;
global symbolPerCarrier;
global bitPerSymbol;
global trainingSymbols;
global trainingSymbols_len;
global CP_len;
global carriers;
len = length(s_in);
SQam = reshape(s_in, nSubC,len/nSubC); %串并转换
PQam = Qam4_mod(SQam);
tmpTable = [-1,1,i,-i];
trainingSymbols_len = 10;
trainingSymbols = (tmpTable(floor(4*rand(trainingSymbols_len,nSubC))+1 ))';
PQam = cat(2,zeros(nSubC,1),PQam);
PQam = cat(2,trainingSymbols,PQam);
carriers = (1: nSubC) + (floor( ifft_len/4) - floor(nSubC/2));
conj_carriers = ifft_len - carriers + 2;
P_IFFT = zeros(ifft_len,1 + symbolPerCarrier + trainingSymbols_len);
P_IFFT(carriers,:) = PQam;
P_IFFT(conj_carriers,:)=conj(PQam) ;
PCh = (ifft( P_IFFT ,ifft_len,1));
PCh2 = cat(1, PCh((ifft_len-CP_len+1):ifft_len,:), PCh); % 添加 CP
s_out = reshape(PCh2, 1, (ifft_len+CP_len)*(symbolPerCarrier +trainingSymbols_len + 1)); %并串转换

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