Comments on "Low-Complexity Power Allocation for Energy Efficiency Maximization in DAS" and a Novel Algorithm for Energy Efficiency Maximization in DAS.

In a recent letter, Wu et al. proposed a low complexity algorithm for maximizing the energy efficiency in distributed antenna systems (DAS). The complexity is shown to be reduced due to decrease in the number of Lambert function calculations. In this letter, we highlight a few mistakes in the proof of Theorem 1 of the Wu et al. letter. Further, we show that the proposed algorithm in the Wu et al. letter cannot achieve optimal power allocation for energy maximization if the number of optimal antennas for a particular user is greater than 1. Finally, we propose a new algorithm to find the optimal power allocation to maximize the energy efficiency in DAS.