資源簡(jiǎn)介
限幅(clipping),是降低OFDM系統(tǒng)PAPR最直接的方法。根據(jù)峰均比的統(tǒng)計(jì)特性可知,高峰平比出現(xiàn)的概率極小,削去過高的瞬時(shí)高幅值,降低整個(gè)系統(tǒng)的誤比特率性能,改善CCDF曲線
代碼片段和文件信息
clear?all;
clc;
fl=512;??%?設(shè)置FFT長(zhǎng)度
Num=100;???
ca=256;?%設(shè)置并行傳輸?shù)淖虞d波個(gè)數(shù)
NN=1:.1:14;?%?CCDF的門限值
ccdf0=zeros(1131);
ccdf1=ccdf0;
ccdf2=ccdf0;
ccdf3=ccdf0;
ccdf4=ccdf0;
?for?i=1:Num???
Signal((i*(i-1)/2)*ca*4+1:(i*(i-1)/2+i)*ca*4)=rand(1ca*i*4)>0.5;%產(chǎn)生0,1?隨機(jī)序列,符號(hào)數(shù)為ca*(1+Num)*Num*2
?end
?Ns=(1+Num)*Num;??%設(shè)置一個(gè)幀結(jié)構(gòu)中OFDM信號(hào)的個(gè)數(shù)
?
for?i=1:ca
????for?j=1:Ns*2
????????SigPara(ij)=Signal(i*j);%串并變換
????end
end
%QPSK調(diào)制,將數(shù)據(jù)分為兩個(gè)通道
for?j=1:Ns
????ich(:j)=SigPara(:2*j-1);
????qch(:j)=SigPara(:2*j);
end
kmod=1./sqrt(2);
ich1=ich.*kmod;
qch1=qch.*kmod;
x=ich1+qch1.*sqrt(-1);?
x1=zeros(4*caNs);???%???過采樣?
???for?i=1:ca/2
???x1(i:)=x(i:);
???x1(i+7/2*ca:)=x(i+ca/2:);
???end
???
?y=ifft(x[]2);?%頻域數(shù)據(jù)變時(shí)域
y1=(abs(y)).^2;??
power_average=mean(y1);
max_power=max(y1);
papr0=10*log10(max_power./power_average);??%?原來的信號(hào)
%?限幅
le=0.5*10^-2;??%限幅電平模值??
y2=y;
ccdf1=ccdf0;
for?i=1:ca
????for?j=1:Ns
????????if?abs(y(ij))>le;
????????????y2(ij)=le.*exp(angle(y(ij))*sqrt(-1));?
????????end??????
????end
end?
y3=(abs(y2)).^2;
power_average_le=mean(y3);
max_power_le=max(y3);
papr1=10*log10(max_power_le./power_average_le);
%?限幅
le=0.8*10^-2;??%限幅電平模值?
y3=y;
ccdf1=ccdf0;
for?i=1:ca
????for?j=1:Ns
????????if?abs(y(ij))>le;
????????????y3(ij)=le.*exp(angle(y(ij))*sqrt(-1));?
????????end???
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