Downlink Linear Transmission Schemes in a Single-Cell Distributed Antenna System with Port Selection

A cellular distributed antenna system (DAS) allows mobile user terminals (UTs) to be served at higher data rates as compared to conventional cellular systems by reducing the path loss and attaining macrodiversity gains. Moreover, such a cellular DAS can be perceived as a distributed multi-user multiple-input multiple-output system. In this paper, the block diagonalization and zero-forcing dirty-paper coding downlink transmission schemes are extended for a single-cell DAS with multi-antenna distributed antenna ports (DAPs) and multi-antenna UTs, where only a subset of all DAPs in the cell transmit to each UT. The aggregate cell spectral efficiency that is achieved by these schemes per frequency-time resource block is compared for both DAS and collocated antenna system (CAS) architectures, subject to the same total power constraint. The gains of the cellular DAS over the cellular CAS are demonstrated, and the effect of the number of antennas per DAP on the performance of the cellular DAS is investigated.