LS & MMSE channel estimators for OFDM

Compares the performance of the LS and MMSE estimators for a 64 sub-carrier OFDM model

Description

Here is a simulation based proof highlighting the superiority of the MMSE[Min Mean Sq Error] channel estimator over the LS[Least Sq] estimator.The two parameters of evaluation turn out to be, quite logically, the SER[Symbol Error Rate] and the Mean Square Error.The channel is assumed to be g(t)=delta(t-0.5 Ts)+delta(t-3.5 Ts)
{Fractionally spaced}.
For more information on the theory and formulae used , please do refer to the paper On "Channel Estimation In OFDM systems" By Jan-Jaap van de Beek, Ove Edfors, Magnus Sandell, Sarah Kate wilson and Petr Ola Borjesson In proceedings Of VTC'95 Vol 2 pg.815-819.The two sub folders contain the code for the simulations related to the two parameters , i.e SER and MSE..

• MATLAB release: MATLAB 6.1 (R12.1)

[sathish narayanan]

 

[Nishanth Ulhas Nair]

Good Paper

[Yubing Zhang]

something wrong in your program

[manohar vijay]

very good

[Masa Saito]

The program has some redundant parts.
I think the codes below are more simple and may be faster.

(original in MSE_compare.m)
l.18
X=zeros(64,64);
l.27-29
for i=1:64
     X(i,i)=d(i);
end

(modified version)
X=diag(d);
 
(original in MSE_compare.m)
l.19-26
d=rand(64,1);
for i=1:64
    if(d(i)>=0.5)
        d(i)=+1;
    else
        d(i)=-1;
    end
end

(modified version)
d=(-1).^round(rand(64,1));

(original in MSE_compare.m)
gg=zeros(64,64);
for i=1:64
    gg(i,i)=G(i);
end

(modified version)
gg=diag(G);

[Xu Maoge]

There may be mistake
(original in MSE_compare.m)
Line 71-72.
variance=var(noise);
N=fft(noise);

(modified version)
N=fft(noise);
variance=var(N);

[Mulugeta Araya]

 

[O oooo]

gg=diag(G);
gg_myu = sum(gg, 1)/64;
->>
gg_myu = G'/64;
???

[O oooo]

gg_myu = sum(gg, 1)/64;
->>
gg_myu = G.'/64;

[O oooo]

gg=zeros(64,64);
%for i=1:64
% gg(i,i)=G(i); %ñòðîèì äèàãîíàëüíóþ ìàòðèöó....
%end -->>>
gg=diag(G);

%gg_myu = sum(gg, 1)/64; %õóéíÿ êàêàÿ òî. òî æå ñàìîå ÷òî G'./64... âåêòîð ñòðîêà.
%-->>>
gg_myu = G.';

gg_mid = gg - gg_myu(ones(64,1),:); %ðàçìíîæèëè âåêòîð-ñòðîêó gg_myu äî ìàòðèöû
sum_gg_mid = sum(gg_mid, 1);
Rgg = (gg_mid' * gg_mid- (sum_gg_mid' * sum_gg_mid) / 64) / (64 - 1);
-->>
Rgg = cov(G);
ãûûû)))

[O oooo]

WRONG!
correct:
N = 64;
for k=0:N-1 % <- error
      s=0;
      for m=1:2
         s=s+(exp(-j*pi*(1/N)*(k+(N-1)*tau(m))) * (( sin(pi*tau(m)) / sin(pi*(1/N)*(tau(m)-k)))));
         %Go through the above cited paper for the theory behind the formula
      end
g(k+1)=s/sqrt(64);
end

[LAM LE]

 

[Juan Miranda]

Useful code, though I think you have a mistake:
for k = 0:N-1
    s=0;
    for m=1:2
        s=s+(exp(-j*pi*(1/N)*(k+(N-1)*tau(m))) * (( sin(pi*tau(m)) / sin(pi*(1/N)*(tau(m)-k)))));
    end
    g(k+1)=s/sqrt(N);
end
G = g';%<--- the "'" operator takes the complex conjugate and transposes. I don't think that is what you want. Perhaps you should use ".'"

[farzad MOAZZAMI]

i like it

[farzad MOAZZAMI]

MMSE is lower band for blind equalization performance. We are trying CMA+AMA blind equalization scheme for QAM signals. Our MSE is below MMSE curve !

[ilshin lee]

 

[Deep Prakash]

I liked your code.I am interested in reading full description and full report. Please send me at: [e-mail]

[akm islam]

send me the code

[akm Islam]

you have done an appreciable work, I need ' MATLAB CODE ON OFDM'. Can anybody help me?

[le bich Hoa]

you have done an appreciable work, I need ' MATLAB CODE ON OFDM'. Can anybody help me?

[Tang Shuiyi]

it is that i am inerested in.thx

[Alejandro]

why if i change the number or value of the taps the program just don't work?

only for your data show a good performance

[xue junfeng]

good