There is an expected shortage in bandwidth resources due to the recent success of, and hence the explosive demand for, wireless services and networks. This expected shortage is not so much due to the scarcity of bandwidth, but due to its inefficient use. There exist plenty of ``opportunities" available along time and frequency dimensions that wireless networks can potentially exploit. It is therefore important to develop a new way of exploiting these opportunities effectively and efficiently.
Recent technological advances make it possible to realize SDRs (Software-Defined Radios) or smart radios that, unlike traditional radios, can switch from one frequency to another at minimum cost, thereby enabling ''opportunistic'' spectrum access along time and frequency dimensions. SDRs empower next-generation wireless networks with adaptive and dynamic multi-band access, but introduce several unique cross-layer challenges. On the other hand, the newly-emerging MIMO (Multiple-Input Multiple-Output) technology has great potential for significant throughput enhancements, better interference suppression, and substantial energy savings. SDRs and MIMOs together form a complete means of enabling opportunistic spectrum access along not only time and frequency dimensions (via SDR), but also space dimension (via MIMO).
This project will, therefore, 1. Model, characterize, and analyze the maximum achievable throughput in MIMO-equipped wireless networks; 2. Derive guidelines for network designers to determine the optimal parameters of wireless networks; 3. Develop innovative techniques that exploit MIMO to reliably support and maintain QoS in MIMO wireless networks; and 4. Implement and evaluate the performance of the developed techniques via simulation and experimentation on a multi-band capable wireless testbed that we are currently building with commercial off-the-shelf components.
The intellectual merit of the proposed research will be: (1) establishment of both theoretical and practical foundations for next-generation wireless networks to be built with advanced technological components such as SDRs and MIMO; (2) design guidelines for selecting the optimal parameters of wireless networks equipped with these advanced components; (3) solutions to the bandwidth-shortage problem, which is key to next-generation wireless networks; and (4) innovative techniques enabling next-generation wireless networks to support and maintain QoS of multimedia applications.
This research will also make broader impacts on: (1) basic research by providing fundamental solutions to challenging problems to be encountered in future wireless networks; (2) regulatory bodies such as FCC by providing rigorously-proven solutions and guidelines for establishing flexible and efficient spectrum policies; and (3) undergraduate and graduate education via integration of research, teaching, and learning, especially the use of the developed solutions and their implementations on the proposed testbed in students' classes and independent study projects.
