A New Full-Rate Orthogonal Space-Time Block Coding Scheme Based on Quaternion

This paper introduces a full rate, full diversity orthogonal space-time block code for 4 transmit antennas. The4times4 codeword matrix consists of four 2times2 Alamouti blocks, and these blocks can be viewed as quaternions which in turn represent rotations in R³. The Alamouti blocks that appear in a codeword are drawn from the icosahedral group. The code is no constellation expansion unlike some full-rate full-diversity codes in the literature. By utilizing the quaternionic form, we can find the decoding algorithm to reduce the complexity of maximum likelihood (ML) coherent decoding.