A Low-Complexity Transmit Diversity Scheme Using Moderate-Sized Signal Constellations

Introduction: Antenna selection scheme was introduced as a low-complexity and low-cost approach for multiple-antenna systems [2]. The idea is to select L antennas out of K antennas (L < K) at the transmitter/receiver side in a way that only L RF chains and a switch are needed in the radio front end. In this Letter, we propose a novel technique to reduce the usage of RF chains in a nT = 2 transmit antennas system. This technique consists of using one RF chain and a low-complexity switch to select the transmit antenna sequentially for transmission. Unlike the antenna selection method, the proposed system does not require any feedback information from the receiver to the transmitter for transmit antenna selection. In what follows, we compare the structure and performance of our proposed system to that of the well-known Alamouti transmit diversity scheme [3].