1.完整项目描述和程序获取
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2.部分仿真图预览
3.算法概述
CP-OFDM（Cyclic Prefix Orthogonal Frequency Division Multiplexing，循环前缀正交频分复用）通信系统采用多个正交子载波（Orthogonalsub-Carrier）并行传输数据，可以高效传输数据并且有效对抗频率选择性衰落信道带来的影响。但是在数据传输过程中，对子载波的正交性有严苛的要求，所以CP-OFDM系统对载波及采样时钟的频率偏差（即频偏）非常敏感，必须通过频偏估计与纠正技术，使得频率偏差处于接收机可容忍范围内，从而保证数据的正确传输。CP-OFDM 技术利用多个平行窄带子载波来传输信息，而不使用单个宽带载波。该技术定义充分，已在 4G LTE 下行链路和Wi-Fi通信标准成功实施，因此也适合用于 5G NR 设计。
4.部分源码
v1 = 1;
v2 = 3;
nBit = 1024*2;
lSymbol = 4;
nChannel = 4;
baseFreq = 100; % 1Hz
tSymbol = nChannel/baseFreq; % time for one symbol
nSymbol = nBit/(nChannel*lSymbol);
bitSequence = bit_generate(nBit);
mapQAM = mapping_16QAM(v1,v2);
for k = 1:nBit/lSymbol
rInd = fix((k-1)/nChannel) +1;
cInd = k-(rInd-1)*nChannel;
fr = (k-1)*lSymbol +1;
bSymbol(rInd,cInd).bit = bitSequence(fr:fr+lSymbol-1);
end
fBase = 100; %100Hz for base frequence
fFirst = 200; %500Hz for first channel
Fs = 1024;
rTg = 1/8; %Ratio of guard
Tsym = 1/fBase;
Tg = Tsym*rTg;
Tsig = nSymbol*(Tsym+Tg);
bSymbol = generateSymbolWave(bSymbol,mapQAM,fBase,fFirst,rTg,Fs);
sOFDM = [];
for k=1:nSymbol
tmpSignal = 0;
for j= 1:nChannel
tmpSignal = tmpSignal + bSymbol(k,j).symbol;
end
sOFDM = [sOFDM tmpSignal];
end
fftOFDM = fft(sOFDM);
fftOFDM = fftshift(fftOFDM);
freq = (-length(sOFDM)/2:length(sOFDM)/2-1)*fBase;
powerOFDM = 0;
for k= 1: length(pOFDM)
powerOFDM = powerOFDM + pOFDM(k);
end
powerOFDM = powerOFDM/length(pOFDM);
snr_lin = 10^(5/10); % 5dB
var = powerOFDM/snr_lin;
%var =2000;
noise = (var/sqrt(2))*(randn(1,length(sOFDM)) +i*randn(1,length(sOFDM)));
sOFDM_fft = fft(sOFDM) + noise*Fs/2;
%sOFDM = sOFDM + abs(noise);
sOFDM = ifft(sOFDM_fft); %add noise into signal
sorted_noise = sort(abs(noise));
dx = 0:0.001:20;
count =1;
Fx = zeros(1,length(dx));
k=1;
while ( k<= length(sorted_noise))
if count <length(dx)
if sorted_noise(k)<=dx(count)
Fx(count)= Fx(count) +1;
k = k+1;
else
count = count +1;
Fx(count) = Fx(count-1);
end
else
Fx(count)= Fx(count) +1;
k=k+1;
end
end
Fx = Fx./length(sorted_noise);
dx1 = 0:0.1:20;
Px = zeros(1,length(dx1));
Px(1) = Fx(100)/(dx(100));
for k = 2:length(dx1)-2
Px(k) =(Fx(k*100)-Fx((k-1)*100))/(dx(k*100)-dx((k-1)*100));
end
A125
