Energy efficiency optimization in wireless communications employing multiple antennas and realistic power consumption model

Abstract

In this work we focus on the energy efficiency in wireless communication networks, especially comparing the advantages of the antenna selection (AS) technique among other multiple-input multiple-output (MIMO) techniques. Therefore, we discuss two different network scenarios: first considering a small base stations (SBS) deployment, and then a device-to-device (D2D) network deployment. In the small SBS scenario we analyze the area energy efficiency (AEE) for antenna selection (AS), maximal ratio transmission (MRT) and spatial multiplexing (SM) techniques. We also employ different interference cancellation levels and a realistic power consumption model. We derive the mathematical representation and our results show that AS has a larger AEE among the other techniques when the demand for system capacity is low, while SM becomes more energy efficient when the demanded capacity is larger. However we observe that AS has more AEE for short distances, which is due to the lower energy consumed by the Radio Frequency (RF) chains in every node. Yet, we can conclude that the system performance with small SBS, in terms of AEE, is strongly dependent on the amount of interference, which at the same time depends on the power consumption model. In addition, our second scenario is the D2D communication network, where we examine the AS technique in comparison with MRT. Furthermore, we also assume that the D2D nodes are distributed according to a homogeneous Poisson process (PPP), which interfere with each other, i.e., share the same spectrum, and they employ a limited number of feedback bits. Therefore, in the numerical result we also observe MRT technique is more spectral efficient than AS regardless of the number of interfering nodes in the area. On the other hand, the distance of the D2D pair has a larger impact in increasing the AEE of the network, with AS outperforming MRT even when the latter employs a larger number of feedback bits. It is also noteworthy the performance of AS in comparison to MRT for short distances when the number of transmit antennas increases, i.e., despite providing higher data rate, measured in terms of the spectral efficiency, the increased number of antennas for MRT does not considerably compromises its energy efficiency.