Transmitter diversity for OFDM systems and its impacts on high-rate wireless networks

Abstract

Transmitter diversity and down-link beamforming can be used in high-rate wireless networks with OFDM for capacity improvement. In this paper, we compare the performance of delay, permutation and space-time coding transmitter diversity for OFDM systems, and its impact on high-rate packet data wireless networks, where relatively high block error rates, such as, 10%, on the wireless links are acceptable using ARQ. As an alternative, we also consider using the same number of transmitter antennas for down-link beamforming in the direction of the desired mobiles. Our investigation indicates that the delay transmitter diversity with QPSK modulation and adaptive antenna arrays can provide good quality of service (QoS) with a low retransmission probability while space-time coding transmitter diversity can provide high peak-rate. However, down-link beamforming together with adaptive antenna arrays, if it is applicable, appears to be a better alternative to transmitter diversity.