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Wireless Communication, Vol 2, No 6 (2010), Pagination:
Abstract
In wireless communication systems, to combat fading, multiple antennas may be equipped at the transmitter and/or the receiver, where multiple antennas may provide spatial diversity gain as well as multiplexing gain. Cooperative diversity, which employs multiple nodes for the simultaneous relaying of a given packet in MIMO wireless networks, has been shown to be an effective means of improving diversity, and, hence, mitigating the detrimental effects of multipath fading. In current cooperative communication schemes, to achieve cooperative diversity, synchronization between terminals is usually assumed, which may not be practical since each terminal has its own local oscillator. In cooperative networks using a decode-and forward strategy, the multiple relays effectively transmit a distributed space–time code, the performance of which can be severely degraded when timing synchronization among the relays is not assured. the new Distributed-threaded algebraic space–time (TAST) codes are effective and flexible, enabling use of different signalling constellations, transmission rates, numbers of transmit and receive antennas, and decoders of varying levels of complexity. Perfect space-time codes (STC) based on cyclic division algebras (CDA), maintain the same properties as perfect codes in the synchronous case. Moreover, these codes preserve their full-diversity in asynchronous transmission. This paper presents a comparative study on the performance of the two schemes.
Keywords
MIMO, TAST, STC, CDA.
