Adaptive Transmission Scheme for Improving Capacity in Distributed Antenna Systems

This paper presents the achievable capacity expressions with analytical closed forms of spatial multiplexing transmission (SMT) and single antenna transmission (SAT) for multicell downlink distributed antenna systems (DAS). Considering that SMT and SAT yield high transmission gains of the center and the edge of the cell, respectively, we also propose switching algorithms depending on a user location. The transmission scheme decides a favorable transmission technique between SMT and SAT through instantaneous or ergodic capacity comparison. Simulation results show that the analytical closed forms well match to the empirical expressions. Furthermore, the proposed transmission schemes are superior to SMT and SAT.