%------------------------------------------
%?EE359?final?project?Fall?2002
%?Channel?estimation?for?a?MIMO-OFDM?system
%?By?Shahriyar?Matloub???????????????
%------------------------------------------
clc;
clear?all;
%close?all;
i?=?sqrt（-1）;
Rayleigh?=?1;
AWGN?=?0;?????????????????????????????%?for?AWGN?channel?
MMSE?=?0;?????????????????????????????%?estimation?technique
Nsc?=?64;?????????????????????????????%?Number?of?subcarriers
Ng?=?16;??????????????????????????????%?Cyclic?prefix?length
SNR_dB?=?[0?5?10?15?20?25?30?35?40];??%?Signal?to?noise?ratio
Mt?=?2;???????????????????????????????%?Number?of?Tx?antennas
Mr?=?2;???????????????????????????????%?Number?of?Rx?antennas
pilots?=?[1:Nsc/Ng:Nsc];??????????????%?pilot?subcarriers?
DS?=?5;??????????????????????????????%?Delay?spread?of?channel
iteration_max?=?200;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%?Channel?impulse?response?%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%

if?（Rayleigh）
????N?=?50;%模擬用到的模型的個(gè)數(shù)
????fm?=?100;%似乎是多普勒頻移
????B?=?20e3;%20000?似乎是抽樣頻率
????fd?=?（rand（1N）-0.5）*2*fm;%產(chǎn)生元素為-fm~fm之間服從均勻分布1*N的向量
????theta?=?randn（1N）*2*pi;%產(chǎn)生均值為零，方差為2pi的服從正態(tài)分布的1*N的向量
????c?=?randn（1N）;
????c?=?c/sum（c.^2）;%正態(tài)分布的矢量對(duì)能量歸一化1*N的向量
????t?=?0:fm/B:10000*fm/B;%產(chǎn)生10001個(gè)點(diǎn)范圍為（0~100/20000）
????Tc?=?zeros（size（t））;
????Ts?=?zeros（size（t））;
????for?k=1:N
????????Tc?=?c（k）*cos（2*pi*fd（k）*t+theta（k））+Tc;%在時(shí)間軸上的每個(gè)點(diǎn)上對(duì)50個(gè)波形碟帶
????????Ts?=?c（k）*sin（2*pi*fd（k）*t+theta（k））+Ts;%在時(shí)間軸上的每個(gè)點(diǎn)上對(duì)50個(gè)波形碟帶
????end
????r?=?ones（Mt*Mr1）*（Tc.^2+Ts.^2）.^0.5;%通過(guò)jakes或者是clark模型產(chǎn)生頻選信道的幅度?行為Mt*Mr列為時(shí)間抽樣點(diǎn)（10001個(gè)點(diǎn)），每行的數(shù)值是一樣的
?????????????????????????????????????????%也就是說(shuō)每對(duì)天線(xiàn)之間的信道都是獨(dú)立同分布的
????index?=?floor（rand（Mt*MrDS）*5000+1）;%元素在（0，5000）之間，行為Mt*Mr列為DS的矩陣，用來(lái)索引r
end

MEE1?=?zeros（1length（SNR_dB））;
MEE2?=?zeros（1length（SNR_dB））;

for?snrl?=?1:length（SNR_dB）
????snrl;
????estimation_error1?=?zeros（Mt*MrNsc）;%用來(lái)存放誤碼的數(shù)量，是一個(gè)行為Mt*Mr列為Nsc（子載波）個(gè)數(shù)的矩陣
????estimation_error2?=?zeros（Mt*MrNsc）;
????
????%%%計(jì)算貝塞爾函數(shù)的值有什么作用呢
????R1?=?besselj（02*pi*fm*（Nsc+Ng）/B）;%0階bessel函數(shù)的數(shù)值，就是一個(gè)數(shù)值，用到了（Nsc+Ng）即OFDM符號(hào)的長(zhǎng)度和B?似乎是抽樣的頻率
????sigma2?=?10^（-SNR_dB（snrl）/10）;

????%%%產(chǎn)生aabb有什么用處呢信道估計(jì)
????aa?=?（1-R1^2）/（1-R1^2+sigma2）;%由貝塞爾函數(shù)值和信噪比確定的值
????bb?=?sigma2*R1/（1-R1^2+sigma2）;%由貝塞爾函數(shù)值和信噪比確定的值?，分母一樣，分子不一樣
????%%%
????
????for?iteration?=?1:iteration_max?%%%設(shè)定最大的疊代次數(shù)
????????%iteration????
????????if?AWGN?==?1???%%不經(jīng)過(guò)AWGN信道
????????????h?=?ones（Mt*Mr1）;
????????else
????????????phi?=?rand*2*pi;?%%%?角度服從均勻分布，產(chǎn)生一個(gè)0~2pi均勻分布的角度
????????????h?=?r（index+iteration）*exp（j*phi）;?%%%??幅度服從瑞利分布，即為r中的元素，每次碟帶，對(duì)應(yīng)的索引不一樣，
???????????????????????????????????????????????%%%??但是有可能對(duì)應(yīng)的元素相同，是一個(gè)行為Mt*Mr，列為DS
????????????%h=rand（Mt*MrDS）;
????????????h?=?h.*（ones（Mt*Mr1）*（exp（-0.5）.^[1:DS]））;%每條徑產(chǎn)生幅度的衰減，是幅度的衰減還是相位的差異？size不變
????????????h?=?h./（sqrt（sum（abs（h）.^22））*ones（1DS））;%為每條徑的幅度歸一化，size不變
????????end

????????CL?=?size（h2）;???????????????%?channel?length，多徑信道，獲得信道的長(zhǎng)度
????????data_time?=?zeros（MtNsc+Ng）;?%?產(chǎn)生發(fā)送數(shù)據(jù)的矩陣，是一個(gè)Mt*（Nsc+Ng）的矩陣?其實(shí)只是發(fā)了一個(gè)OFDM符號(hào)
????????data_qam?=?zeros（MtNsc）;???

?屬性????????????大小?????日期????時(shí)間???名稱(chēng)
-----------?---------??----------?-----??----

?????文件????1807816??2007-11-29?17:00??mimo-ofdm?信道估計(jì)\Channel?Estimation.pdf

?????文件????5427395??2005-02-25?15:37??mimo-ofdm?信道估計(jì)\IST_FLOW?Selected?MIMO?Techniques?and?their?Performance?d14.pdf

?????文件?????559204??2005-01-06?22:25??mimo-ofdm?信道估計(jì)\mimo?simulator\A?space-time?correlation?model?for?multielement?antenna?systems?in?mobile?fading?channels.pdf

?????文件?????393942??2005-01-06?22:24??mimo-ofdm?信道估計(jì)\mimo?simulator\Efficient?simulation?of?space-time?correlated?MIMO?mobile?fading?channels.pdf

?????文件??????47024??2005-01-06?21:57??mimo-ofdm?信道估計(jì)\mimo?simulator\MIMOsimSpectral.p

?????文件???????6247??2005-01-06?21:57??mimo-ofdm?信道估計(jì)\mimo?simulator\MIMOsimSpectralHelp.m

?????文件???????9079??2009-03-16?14:10??mimo-ofdm?信道估計(jì)\MIMO_OFDM_channel_estimation.m

?????文件???????9080??2007-11-29?20:05??mimo-ofdm?信道估計(jì)\wo_MIMO_OFDM_channel_estimation.m

?????目錄??????????0??2009-03-16?19:35??mimo-ofdm?信道估計(jì)\mimo?simulator

?????目錄??????????0??2009-03-13?17:00??mimo-ofdm?信道估計(jì)

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??????????????8259787????????????????????10