Mau-Luen Tham, Member, IEEE, Su Fong Chien, Derek William Holtby and Shavkat Alimov
In this paper, we propose an energy-efficient power allocation scheme for the downlink multiuser distributed antenna systems (DAS). The objective is to maximize the energy efficiency (EE) under the constraints on per-antenna transmitpower and proportional data rates among users. Since EE function is typically defined in fractional form, it is computationally complex to optimize the EE directly. We first convert the nonlinear fractional problem into an equivalent but better tractable problem, based on which we derive an iterative algorithm to obtain the global optimum of the considered problem. On top of being optimal, the solution is also lightweight since only a single-variable nonlinear equation needs to be solved. Furthermore, we can flexibly switch toanother mode of operation which delivers relatively higher spectral efficiency (SE) at the expense of losing EE. Numerical simulations and complexity analysis validate that the proposed scheme achieves much higher SE and EE performance with strictersatisfaction of the proportional rate constraints and lower complexity, compared to the state-of-the-art schemein literature.
IEEE Transactions on Green Communications and Networking