Millimeter-Wave Spatial Multiplexing in an Indoor Environment

A unique feature of communication at millimeter (mm) wave carrier frequencies is that spatial multiplexing is available for multiple-input multiple-output (MIMO) links with moderate antenna spacing even without a rich scattering environment. In this paper, we investigate the potential for exploiting this observation for increasing the spectral efficiency of indoor 60 GHz links. We begin by establishing limits on the spatial degrees of freedom available for linear antenna arrays of constrained length. A system architecture designed to exploit the available degrees of freedom, including beamforming as well as spatial multiplexing, is proposed. We evaluate the link capacity achievable by the proposed architecture when operating in a simple indoor environment. The results illustrate the relationship between between the channel quality and the relative positions of the transmit and receive nodes.