A Full Diversity Full Rate 4-Antenna Alamouti Code

4-antenna Alamouti code has been regarded as an effective transmit diversity scheme in existing and/or upcoming wireless communication systems for its simplicity and its compatibility with orthogonal 2-antenna Alamouti code. In this paper, an improved 4-antenna Alamouti code is presented. The new code can achieve full diversity through constellation rotation, thus it outperforms the original 4-antenna Alamouti code significantly. In addition, the optimal receiver for the new code can decouple the ML decoder of four symbols into two ML decoders of two symbols, leading to low decoding complexity. This paper also presents simulation and analysis results demonstrating the advantages of the improved 4-antenna Alamouti code