Iterative Channel Estimation in LTE Systems

In this paper, we discuss iterative channel estimation for the Long Term Evolution (LTE) downlink. The LTE standard utilizes coherent detection and therefore to achieve a high data rate over mobile radio channels, it is essential to obtain high accurate channel state information at the receiver side. For channel estimation purposes, the LTE standard provides training data known as pilot symbols. The open question is whether the accuracy of channel estimation based on pilot symbols is sufficient to achieve such high data rate transmission. The quality of the channel estimates can be further enhanced if soft or hard information bits, which are available after the decoding stage, are utilized by the channel estimator to re-estimate the channel. In order to quantify the gain provided by the iterative channel estimation, several scenarios have been considered in this work.