Diversity Combining via Universal Orthogonal Space-Time Transformations

Receiver diversity methods play a key role in combating the detrimental effects of fading in wireless communication and other applications. Commonly used linear diversity methods include maximal ratio combining, equal gain combining and antenna selection combining. A novel linear combining method is proposed where a universal orthogonal dimension-reducing space-time transformation is applied prior to quantization of the signals. The scheme may be considered as the counterpart of Alamouti modulation, and more generally of orthogonal space-time block codes. The scheme is well-suited to reduced-complexity multiple receive-antenna analog-to-digital conversion of narrowband signals. It also provides a method to achieve diversity-enhanced relaying of communication signals, for multi-user detection at a remote terminal, minimizing the required bandwidth used in the links between relays and terminal.