Analysis of pilot-symbol aided channel estimation for OFDM systems with multiple transmit antennas

This paper addresses pilot-symbol aided channel estimation (PACE) for OFDM based systems employing multiple transmit antennas. Two approaches are investigated: first, all N/sub T/ transmit antennas use all available pilot symbols simultaneously, resulting in N/sub T/ superimposed signals; second, a subset of available pilots is allocated for each transmit antenna exclusively. The Wiener filter and the corresponding mean square error (MSE) are derived. By applying the sampling theorem, the minimum number of pilots required to estimate the channel of N/sub T/ superimposed waveforms is derived.

I. Introduction

Multi-carrier modulation, in particular orthogonal frequency division multiplexing (OFDM) [1], has been successfully applied to various digital communications systems. OFDM can be efficiently implemented by using the discrete Fourier transform (DFT). Furthermore, for the transmission of high data rates its robustness in transmission through dispersive channels is a major advantage.