New Signal Processing Techniques for MIMO Physical Layer

Abstract

Multiple-inputmultiple-output (MIMO) systems, characterized by multiple antenna transceivers, add a ‘space’ dimension to signal processing for wireless communication. Conventionally, the degrees of freedom (DoFs), i.e., the number of independent data streams that can be transmitted or received, available in the space dimension are utilized to improve the quality-of-service and the data rates. In other words, the spatial DoFs are exploited to gain diversity and multiplexing benefits. However, these DoFs may be used for other purposes (including multicasting, duplexing, and multipath resolution), which are conceivable given the emerging trend of accommodating more and more antennas in wireless terminals. Developing new physical layer signal processing techniques to realize such non-conventional benefits and ascertaining their viability through performance analysis are the main goals of this thesis. GSVD beamforming, which generalizes eigenmode transmission and zero forcing beamforming techniques for two-user MIMO downlink channels, and spatial multipath resolution, a unique application of spatial signal processing to mitigate multipath fading, are proposed here for the first time. Moreover, beamforming techniques for physical-layer multicasting and space division duplexing are developed in detail; the exact performance of channel inversion power allocation over eigenmode transmission is characterized. This thesis develops each of those contributions in detail.