Discrete lens array modeling and design for optimum MIMO communications at mm-wave

Millimeter-wave wireless systems are emerging as a promising technology for meeting the exploding capacity requirements of communications networks. In particular, Multiple- Input Multiple-Output (MIMO) systems have been explored as a method of increasing the capacity of line-of-sight links, as an attractive alternative to fiber-based wired backhaul. A key limiting factor for conventional mm-wave MIMO has been achieving optimal performance, which requires a critically-spaced antenna array and high transceiver complexity. Efforts to reduce the complexity, e.g. with a few widely spaced antennas, lead to significantly decreased performance. Continuous Aperture Phased MIMO (CAP-MIMO) is a hybrid digital-analog transceiver architecture that uses a high-resolution Discrete Lens Array (DLA) for analog spatial beamforming. The DLA enables direct access to the communicating modes, resulting in an optimal MIMO system with dramatically low transceiver complexity. This paper discusses the design, fabrication, and analysis of a prototype DLA-based CAP-MIMO system, using both analytical and measurement results.