Low Complexity Decision-Directed Channel Estimation Based on a Reliable-Symbol Selection Strategy for OFDM Systems

This paper presents a low-complexity/low-latency algorithm for estimating and tracking time-varying fading channels in Orthogonal Frequency Division Multiplexing (OFDM) systems. More specifically, it is described a decision directed (DD) channel estimation (CE) method, consisting of two main steps: 1) Data detection of the current received OFDM symbol is performed by using the channel coefficients estimated in correspondence to the previous OFDM symbol; 2) The channel corresponding to the current OFDM symbol is estimated by using a subset of the newly detected data symbols. The data subset, used to perform successive refinement on the channel estimation, is found by choosing the OFDM subcarriers with the highest expected signal-to-noise ratio (SNR). Such a subcarrier selection strategy aims to obtain robustness against the introduction of incorrect data symbols in the channel estimation process. The extension of the presented technique to multiple receive antennas is also discussed. The proposed estimation method is potentially useful for IEEE 802.11p compliant vehicular communication systems, whose basic modulation parameters are herein used for computer simulation of the information error rate.