Design of Optimal Space-Time Codes in TDD/TDMA 4G systems

Under the scenarios of fast mobile frequency selective channels, it is a very intractable issue to design the optimal space time codes (ST) that can achieve the optimal diversity and multiplexing gains tradeoff with full-diversity full-rate (FDFR) constrains. Therefore, an optimal space time design scheme is given in this paper for one novel 4G cellular communication systems with time division duplex (TDD) and time divisions multiple access (TDMA). The system is designed to overcome the great channel estimation overhead and the complexity of multiple user detectors in the cases of multiple antennas at transceivers. Here, one FDFR code given in recent literatures is adopted for the proposed TDD/TDMA 4G systems, which was proved in this paper to achieve the optimal diversity-multiplexing gain tradeoff. In typical cellular channel profiles, several space time schemes with optimal or sub-optimal tradeoff are tested with TDD/TDMA 4G systems with 8x2 antenna configurations at base and mobile stations respectively. Numerical results show that the FDFR design could achieve the maximal system throughout with better adaptive capacity to wireless link states than that of space time block codes (STBC) and Diagonal Bell Laboratories Layered Spare-Time Codes (D-BLAST). Furthermore, the performance of the proposed FDFR design for TDD/TDMA 4G systems could achieve better tradeoff for throughput and system symbol error rates than that of the cyclic-division-algebra (CDA) space time codes. Key-words: MIMO, diversity and multiplexing tradeoff, 4G, space time codes, full-diversity and full-rate