OFDM with pilot and equalizer

[raymawri]

Hello,

I would like a matlab code for OFDM with pilot and different types of equalizers. I have a matlab code for OFDM without the equalization. I am having hard time incorporating the equalization into the OFDM.

Please advise

 

[David83]

Equalization in OFDM with perfect subcarrier orthogonality is to done by multiply the received OFDM symbol by the inverse of a diagonal matrix that result from taking the FFT of the circular channel matrix. It's a one tap frequency domain equalizer. My guess is that your code performs it, but you don't realize it.

 

[promach]

Hi David83,

Why for each subband of OFDM, we only need 1-tap equalizer ? only 1-tap ?

 

[David83]

Conceptually, OFDM transforms a frequency selective channel into a number of frequency flat channels. In each subband k, the received signal can be written as

Yk=Hk*Xk+Wk

where Hk is the frequency response of the channel at frequency k, Xk is the transmitted symbol over frequency k, and Wk is the AWGN. So you need a one tap equalizer for each band, namely for subband k it's 1/Hk.