OFDM pilot subcarriers

Discussion in 'Wireless & RF Design' started by thavamaran, Nov 8, 2010.

  1. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
    Hi guys, I am designing my OFDM system, actually have designed, I am using 128 subcarriers, 72 of it carriers my data, and 56 are zero padded, 27 subcarriers of zeros at the beginning which are at DC, then 36 subcarries of data, then 2 subcarries of zeros in the middle, then again with 36 subcarriers of data, at the end another 27 subcarries with zeros.

    So 27 beginning, 2 in the middle and 27 at the end (Nyquist frequency). Correct me if I padded it wrongly.

    Then now I am having problem at the end of my constellation, I have a phase shift because Im using a nonlinear laser model in between the channel, so to do the channel estimation now, I need to add Pilot symbol. I went through a few books and papers, but I still dont get the idea of Pilot symbol.

    Can anyone rigorously explain to me why pilot tone, how to include them in subcarrier and a bit of explanation on that, please, thank you very much.