Transmit Diversity with Single Transmitter Using Switch and 180° Hybrid

Abstract

Generally, two synchronized transmitters are required to implement transmit diversity, such as Alamouti codes. However, because two transmitters are used, many disadvantages arise, such as increased price, power consumption, complexity, and the necessity of synchronization and calibration. In this paper, we proposed a new method to realize transmit diversity only using one transmitter. The proposed method combines baseband signal processing and an RF circuit, which connects a 180° hybrid and one switch between one transmitter and two transmit antennas, and controls the switch at the mid-point of the transmission bit. Because the proposed system has only one transmitter, the power consumption and hardware cost can be reduced by half, and the diversity gain can be realized in a fading environment. We verified the feasibility of the proposed method by computer simulations and confirmed that diversity operation can be realized using hardware.