A MIMO-OFDM channel estimation approach using time of arrivals

Channel estimation is critical in designing multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems for coherent detection and decoding. We propose a channel estimation scheme based on time of arrivals (TOAs) estimation. The TOAs are first determined using a variant of probabilistic data association (PDA) and employing the minimum description length principle, then the PDA is augmented by group decision feedbacks to refine the TOA estimates. With the channels of typical urban and hilly terrain delay profiles, simulation results, compared with the alternating projection (AP) and the Fourier transform based methods, show that the proposed scheme provides a promising accuracy-complexity trade-off for MIMO OFDM channel estimation.

I. Introduction

The multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) is one of the most promising techniques for broad-band wireless communications. Channel estimation has been successfully used to improve the performance of OFDM systems. For instance, differential detection would result in a 3-dB loss in signal-to-noise ratio (SNR) compared with coherent detection, where channel parameters are required. Most diversity schemes are designed with the assumption that the channel information is available. For example, channel estimation is crucial for the receiver combining or decoding of space-time code. Therefore, channel estimation is essential in MIMO-OFDM system design.