An iterative algorithm for joint antenna selection and power adaptation in energy efficient MIMO

As the growth of wireless communications is accompanied by increased energy consumption, energy-efficient communication is becoming imperative. This paper will discuss the energy efficiency of MIMO systems with antenna selection. The optimal method for the maximization of energy efficiency is exhaustive search. To address the problem, an iterative algorithm which includes the transmit antenna selection and power adaptation is proposed. It is based on the iterative property of the energy efficiency, which is derived in this paper. This property guides us to select the antenna that achieves the largest energy efficiency increment at each step. There is also a power adaptation for each step where we calculate the optimal transmission power and then set it as the initial one for the next step. Moreover, one asymptotic property exists in the proposed algorithm, which states that the antenna selection and power adaptation can be decoupled in high and low SNR regimes. This fact reduces the complexity further and enables us to achieve the optimal performance with a greater probability. Simulation results show that the proposed algorithm achieves near-optimal performance in all the SNR regimes and has a remarkable gain over the no selection scheme in the energy efficiency and transmission power.