Abstract:

This paper investigates the multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) transmission over doubly selective channels and focuses on maximum likelihood channel estimator using pilot tones in frequency domain. We derived the system model for MIMO-OFDM over doubly selective channels. Using this model,we gave the lower bound of the mean squared error of maximum likelihood channel estimator and this bound was served as the design criterion to derive the optimum pilot tones. Simulations show that the channel estimator using the proposed pilot can approach the theoretical lower bound.

Key words: doubly-selective channels, channel estimaion, optimum pilot tone