 
Summary: Blind Channel Estimation in OFDM Systems by
Relying on the Gaussian Assumption of the Input
T. Y. AlNaffouri1 and A. A. Quadeer2
Electrical Engineering Department
King Fahd University of Petroleum & Minerals
Dhahran, Saudi Arabia
{naffouri1
, aquadeer2
}@kfupm.edu.sa
Abstract In an OFDM system, the receiver requires an estimate
of the channel to recover the transmitted data. Most channel esti
mation methods rely on some form of training which reduces the
useful data rate. Here instead we blindly estimate the channel by
maximizing the log likelihood of the channel given the output data.
Finding the likelihood function of a linear system can be very difficult.
However, in the OFDM case, central limit arguments can be used to
argue that the timedomain input is Gaussian. This together with the
Gaussian assumption on the noise makes the output data Gaussian.
The output likelihood function can then be maximized to obtain the
maximum likelihood (ML) estimate of the channel. Unfortunately,
