Virtual Space-Time Coding for Achieving Transmit Diversity without Antenna Array

Abstract

In this paper, we propose a virtual transmit diversity scheme which is able to achieve a full transmit diversity gain with only single transmit antenna. We use locally generated random sequences at a transmitter to emulate independent space-time coded channel coefficients to achieve full transmit diversity gain at the receiver. The performance of such a virtual transmit diversity scheme is analyzed and compared with traditional Alamouti transmit diversity scheme. The properties of locally generated fading channel coefficients to achieve 2×1 virtual transmit diversity gain are studied and it is revealed that either Gaussian or evenly distributed random sequences can be applied to the virtual transmit diversity schemes. The 2×1 virtual transmit diversity scheme will also be generalized to N(subscript t)×1 virtual transmit diversity scheme in this paper. The work is significant to introduce a new sub-optimal approach to achieve N(subscript t)×1 transmit diversity at a very low complexity.