On the switching rate of ST-MIMO systems with energy-based antenna selection

The increased hardware complexity required to implement the multiple RF chains associated with the multiple antennas in MIMO systems, has led to various antenna selection methods for utilizing only a subset of the total available antennas. Some of these selection methods require the instantaneous channel state information (CSI) of the communication paths between the antennas, while other require only a sampling of the signal-plus-noise component. At first look, the latter method seems to offer a considerable reduction of the overall system complexity. However, if the switching rates (i.e. the rate at which the antenna subset changes) are taken into account, the decision of which of the two methods is the most appropriate one, becomes difficult. In this paper, we examine the switching rate (SWR) of these two antenna selection approaches, providing insight into the trade-off between the switching rate and the complexity imposed by the CSI requirements.