clear;?close?all;?clf

Nfft?=?32;
Ng?=?Nfft/8;????????????%?guard?space?
Nofdm?=?Nfft+Ng;
Nsym?=?100;
Nps?=?4;????????????????%?pilot?spacing?
Np?=?Nfft/Nps;??????????%?number?of?pilots?per?OFDM?symbol
Nbps?=?4;???????????????%?number?of?bits?per?（modulated）?symbol
M?=?2^Nbps;

modobject?=?modem.qammod（‘M‘M?‘SymbolOrder‘‘gray‘）;
demodobject?=?modem.qamdemod（‘M‘M?‘SymbolOrder‘‘gray‘）;

Es?=?1;
A?=?sqrt（3/2/（M-1）*Es）;?%?Signal?energy?and?QAM?normalization?factor
SNR?=?30;
MSE?=?zeros（16）;
nose?=?0;
for?nsym?=?1:Nsym
????Xp?=?2*（randn（1Np）>0）-1;???????????????%?Pilot?sequence?generation
%?????msgInt?=?randi（1Nfft-NpM）;????????????%?bit?generation
????msgInt?=?round（15*rand（1Nfft-Np））;
????data?=?A*modulate（modobjectmsgInt）;???%?QAM?modulation
????
????ip?=?0;
????pilotLoc?=?zeros（1Np）;
????X?=?zeros（1Nfft）;??????????????????????%?data?on?sucarriers
????for?k?=?1:Nfft
????????if?mod（kNps）==1
????????????X（k）?=?Xp（floor（k/Nps）+1）;?
????????????ip?=?ip+1;
????????????pilotLoc（ip）?=?k;
????????else
????????????X（k）?=?data（k-ip）;
????????end
????end
????x?=?ifft（XNfft）;?
????xt?=?[x（Nfft-Ng+1:Nfft）?x];?????????????????????%?IFFT?and?add?CP
????
????h?=?[（randn+1j*randn）?（randn+1j*randn）/2];??????%?a?（2-tap）?channel
????chLen=length（h）;????????????????????????????????%?real?channel?and?its?length
????H?=?fft（hNfft）;
????HPowDb?=?10*log10（abs（H.*conj（H）））;?????????????%?real?channel?power?in?dB
????
????yChan?=?conv（xth）;?????????????????????????%?channel?path?（convolution）
????yt?=?awgn（yChanSNR‘measured‘）;????????????%?add?gaussian?noise?
????y?=?yt（Ng+1:Nofdm）;?????????????????????????????%?remove?CP
????Y?=?fft（y）;
????
????%?LS?/?MMSE?channel?estimation
????for?m?=?1:3
????????if?m?==?1
????????????HEst?=?MMSE_chan_est（YXppilotLocNfftNpshSNR）;
????????????method?=?‘MMSE‘;????????????????????????%?MMSE?estimation
????????elseif?m?==?2
????????????HEst?=?LS_chan_est（YXppilotLocNfftNps‘linear‘）;
????????????method?=?‘LS-linear‘;???????????????????%?LS?estimation?with?linear?interpolation
????????else
????????????HEst?=?LS_chan_est（YXppilotLocNfftNps‘spline‘）;
????????????method?=?‘LS-spline‘;???????????????????%?LS?estimation?with?spline?interpolation
????????end
????????HEstPowDb?=?10*log10（abs（HEst.*conj（HEst）））;
????????
????????%?DFT-based?channel?estimation
????????hEst?=?ifft（HEst）;
????????hDft?=?hEst（1:chLen）;
????????HDft?=?fft（hDftNfft）;
????????HDftPowDb?=?10*log10（abs（HDft.*conj（HDft）））;
????????
????????%?plot
????????if?nsym?==?1
????????????subplot（319+2*m）;
????????????plot（HPowDb‘b‘）;?grid?on;?hold?on;
????????????plot（HEstPowDb‘r:+‘）;
????????????legend（‘True?Channel‘method）;
????????????
????????????subplot（320+2*m）;
????????????plot（HPowDb‘b‘）;?grid?on;?hold?on;
????????????plot（HDftPowDb‘r:+‘）;
????????????legend（‘True?Channel‘[method?‘?with?DFT‘]）;
????????end
????????
????????%?record?MSE?of?estimators.
???

?屬性????????????大小?????日期????時(shí)間???名稱
-----------?---------??----------?-----??----
?????文件?????????661??2017-12-18?11:52??channel?estimation\LS_chan_est.m
?????文件????????1334??2017-12-18?11:52??channel?estimation\MMSE_chan_est.m
?????文件????????3979??2017-12-18?10:18??channel?estimation\channel_estimation.m
?????文件?????????823??2017-12-18?11:51??channel?estimation\interpolate_chan.m
?????目錄???????????0??2017-12-18?11:52??channel?estimation\