The performance gain of space time transmit diversity (STTD) for coded OFDM systems using space time block coding (STBC) is investigated. In particular, it is proposed to use pilot patterns, which are orthogonal in both the frequency and time directions. Therefore, to obtain channel estimates from the separate transmit antennas the receiver can use either adjacent pilots in the frequency direction or adjacent pilots in the time direction. Introduction: Orthogonal frequency division multiplexing

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... (OFDM) is commonly used for high data rate wireless applications due to its inherent ability to combat inter-symbol interference (ISI). To achieve optimum performance with such systems, time and frequency interleaving are used with channel coding to yield the full benefits of time and frequency diversity. However, to obtain time diversity, the size and corresponding delay of the time interleaver become prohibitively large for channels with low Doppler frequencies. In such channels, the use of space diversity can yield large gains. Space diversity can be implemented as multiple antennas at the receiver (receiver diversity), multiple antennas at the transmitter (transmit diversity) or a combination of the two. In this Letter, we examine the use of transmit diversity using space time block coding (STBC).