Schemes of Power Allocation and Antenna Port Selection in OFDM Distributed Antenna Systems

This paper studies the power allocation (PA) and distributed antenna (DA) selection in the downlink orthogonal frequency division multiplexing distributed antenna systems (OFDM-DAS). Two schemes are analyzed, with the objective of maximizing the downlink received signal power. In the first scheme, the DA selection is based on large-scale fading only and the related PA is simple. It is proved that at most three DA ports are enough for the transmission. In the later scheme, the DA selection is based on both large-scale and small-scale fading, and an optimal power partition result to the utilized DA ports is shown for each individual subcarrier. Then a novel resource allocation problem with suboptimal objective is formulated, which is modified to an integer program for complete solution. Finally, the advantages of the two schemes are combined and a suboptimal algorithm is proposed. Simulation compares various transmission strategies of OFDM-DAS and the proposed algorithm shows promising performance.