The development of smart active antenna array front ends with optical/digital processing back ends is proposed. The objective is to demonstrate that: Smart (adaptive) antennas improve adverse interference effects in wireless communication systems; Active smart antenna arrays increase radiated power with reduced cost and power consumption, increase dynamic range, increase reliability and reduce cost, with built-in angle-of arrival detection; Nonlinear optical components provide a simpler, potentially low-cost alternative to digital signal processing and can be easily integrated with active microwave and millimeter-wave arrays.
Interfering signals can be both spatially and temporally varying, causing interference to depend on time as well as on the physical location of the users and surrounding area. To mitigate interference problems, smart antennas create a spatial division multiple access network. Currently, there are not many commercially used smart antenna wireless systems, but several companies have used smart antennas to steer nulls and reduce interference, with increase range and capacity for the same transmitted power, with additional reduced maintenance cost. Smart antennas are also attractive to providers because they provide flexibility as systems grow. The approach taken in this proposal involves a new type of adaptivity for antenna arrays, through a new front end architecture, aided by unique capabilities of nonlinear optical processing. Specific arguments are that: (1) introducing adaptation at the analog front end eases the burden on the signal processing and adaptation becomes faster and more energy efficient with no cost increase (and possible decrease); and (2) nonlinear holographic optical processing can be efficiently used to perform part of the signal processing, with reduction in power consumption, size and cost..
This proposal focuses on systems with: (1) a transmit/receive active lens antenna array front end; (2) resonant electro-optic conversion; and (3) nonlinear active optical interconnects. In order to validate the goals of cost, size and power consumption reductions, a benchmark DSP adaptive processor (4) is proposed.
Interdisciplinary expertise in microwave/millimeter wave active antenna arrays, and nonlinear optics is needed, along with knowledge of the interference properties in a wireless channel and an understanding of the most practical adaptive algorithms. Students involved in this work will gain a broad knowledge base while working on challenging fundamental research problems. This is a collaborative effort with Qualcomm (a world leader in wireless communications), the French Thomson CSF (one of the leaders in optically controlled antenna beam-forming), and the Netherlands Foundation for RadioAstronomy (a scientific institution with strong interests in adaptive arrays). ***
