Optimizing the energy efficiency of SIMO receivers with compact uniform linear arrays

The energy efficiency of a multi-antenna receiver is influenced by the configuration of the antenna array it employs, e.g. with more receive antennas, larger capacity can be obtained while power dissipation is expected to increase. When compact uniform linear arrays are considered, the distance between adjacent antennas becomes a critical parameter due to its close relation to both spatial correlation and antenna mutual coupling, which are the major effects introduced by compact antenna arrays. In this paper, we formulate the optimization of energy efficiency with respect to both the antenna spacing and the number of antennas, and perform extensive numerical experiments to evaluate the gain that can be achieved by applying the optimization results. Moreover, we demonstrate the effects of various system parameters on the optimal antenna spacing, including mean angle of arrival, angle spread, average channel gain, and antenna loss factor, and propose also a simple approximation method to greatly reduce the complexity in finding the optimal spacing.