Energy efficiency comparison between orthogonal and co-channel resource allocation schemes in distributed antenna systems

Distributed antenna systems (DAS) are deployed not only for enhancing coverage, but also for reducing the transmission power consumption, which have emerged as the promising candidate for energy-efficient wireless communications. In this paper, orthogonal and co-channel resource allocation schemes considering energy efficiency in single-cell DAS are analyzed. For orthogonal resource allocation scheme, the interference is avoided by sacrificing the available resources. While for the co-channel resource scheme, the spectrum efficiency improves under the expense of increasing the interference. The close-form expressions of spectrum and energy efficiency of these two schemes are derived, by which the impact of transmission power on spectrum and energy efficiency are theoretically compared. Both the theoretical analysis and simulation results indicate that increasing transmission power beyond a reasonable level will seriously impair energy efficiency. Furthermore, the DAS with co-channel resource allocation scheme is recommended to utilize in the green communication systems.