Flexible Complexity Fast Decoding of Multiplexed Alamouti Codes in Space-Time-Polarization Systems
Space-time coding is of great interest as the introduction of multiple antenna elements at the transmitter and receiver of a wireless communication system is known to increase the system capacity. The Alamouti code is a popular space-time code for a system with two transmit and one or more receive antenna elements. It enables an exact Maximum Likelihood (ML) decoder with linear decoding complexity, i.e., a complexity order O(M), for a modulation scheme with constellation size M. The Alamouti code is rate one and full diversity, transmitting two symbols coded across two transmit antennas and two time slots. Multiplexing two Alamouti component codes enables transmission of four symbols in two time slots.