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Aydar Zimaliev

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08 Dec 2011 OFDM LSE Channel Estimation the performance of LSE channel estimation will be evaluated based on bit error rate in received data Author: Hamid Ramezani

Hello Hamid,
Thanks again. Didn't have to wait this time another 2 years ;)
Ok, now I understood what you mean.
Must admit, it was quite confusing - your script actually doesn't provide only pure link-level simulation results but has also some system-level assumptions on top of it.

07 Dec 2011 OFDM LSE Channel Estimation the performance of LSE channel estimation will be evaluated based on bit error rate in received data Author: Hamid Ramezani

Hi Hamid,
thanks for your reply.
I dont remember what i meant by different power on data and pilots nor the details of your code. Maybe i was wrong about the power thing but i see now in your code:

Ep = 2; % energy in pilot symbols in comparison to energy in data symbols.

Anyways, what I wanted to point out that according to your BER plot when you increase pilot power (Ep) you performance gets bad, ex.: compare Ep=10 vs Ep=1. BER (Ep=10) must have best performance. And I think the problems is in a wrong Noise generation.

Aydar.

15 Jun 2010 Compute N x N DFT matrix Computes DFT matrix for DFT modulation Author: Rajkumar Ramasamy

1)cos and sin you can substitute with exp().

2)or you could write simply M = fft(eye(N)).*1/sqrt(N); to get the matrix.

cheers

27 Nov 2009 OFDM LSE Channel Estimation the performance of LSE channel estimation will be evaluated based on bit error rate in received data Author: Hamid Ramezani

While I was commenting (above) I noticed something strange in your picture above: when you increase pilot power (Ep) you performance gets bad, which is wrong! More power you have on pilots the better channel estimation => the better performance must be.
Your bug is at the noise generation, which should not be a function of pilot power ( when we set SNR we mean SNR on data symbols and not on data+pilot symbols). What your code does it increases noise on data symbols when Pilot power (Ep) is increased.

Instead of

TxDataIfftGiNoise = awgn(TxDataIfftGi , SNR - db(std(TxDataIfftGi)));

I would write

TxDataIfftGiNoise = awgn(TxDataIfftGi , SNR);

or better without Matlab built-in function

TxDataIfftGiNoise = TxDataIfftGi*10^(SNR/20)+1/sqrt(2)*(randn(length(TxDataIfftGi),1)+j*randn(length(TxDataIfftGi),1));

Overall, your code is a very nice example, thank you for sharing with us!

27 Nov 2009 OFDM LSE Channel Estimation the performance of LSE channel estimation will be evaluated based on bit error rate in received data Author: Hamid Ramezani

Very good!

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