Efficient use of limited spectrum is emerging as a major issue in wireless systems. The proposed work focuses on technologies that provide better understanding of wireless networks and greatly enhance spectrum efficiency. with three coupled thrusts: (i) wireless network modeling; (ii) mechanisms for efficient spectrum sharing; and (iii) exploiting enhanced spectrum efficiency for wireless video communications. The project also includes an experimental research component in which the developed approaches will be implemented and tested on the cognitive radio testbed hosted at Virginia Tech and the cooperative networking testbed hosted at NYU-Poly.
The proposed research plans to systematically investigate several of the unique technical challenges and open problems in enhancing radio spectrum efficiency, and supporting emerging video services. This fundamental research will support the development of technologies that achieve new levels of efficiency and quality in wireless broadband services, and will help alleviate the wireless bandwidth limits now being experienced. The work is supported by the Industry Advisory Board as well as individual industry members of the center and has the potential to extend the centers portfolio. The PIs plan to disseminate the work to their industry members and the broader industry and academic community via open-source software as wel as introduce the content within their degree and outreach programs.
Wireless access networks have entered a period of unprecedented change and ever-increasing importance to the economy and society. To accommodate the predicted drastic increase in wireless data volume, and to cater the many emerging wireless multimedia applications, there is a compelling need for developing new wireless network modeling tools to gain the much needed understanding of fundamentals of the new network paradigm, as well as developing new technologies or mechanisms to use the spectrum efficiently. This FRP project focus on three aspects: 1) Modeling Future Wireless Networks: The goal is to develop a model to describe the locations of base stations and mobile users, so that the signal strength, interference and throughput can be modeled more accurately. 2) Efficient Sharing of Radio Spectrum: The study will lead to the development of a auction designs that guarantee efficient spectrum allocation. 3) Cooperative and Cognitive Wireless Video Communications: The goal is to harness the enhanced spectrum efficiency by allowing different network entities to deliver video cooperatively. The participating institutions for this collaborative research effort are Polytechnic Institute of New York University (NYU-Poly), The University of Texas Austin (UT Austin), The University of Virginia (UVa), Virginia Tech, and Auburn University (Auburn). NYU-Poly's contribution to this project mainly focused on the development of cooperative video communication schemes and we focused on two kinds of cooperation. The first system we studied is based on user cooperation, i.e., all mobile nodes in the network assist each other in information delivery. We designed a cooperative multicast scheme that allows not only the base stations, but also the mobile stations that are close to the base stations to delivery video packets to edge users. We derived the optimum video rates that can be sustained at the edge. The results show that this new scheme can support significantly higher video rates than the prior approaches. The other system we studied is on cooperation between network infrastructures, i.e., the operator deploys multiple fixed relay stations to provide better service to the mobile stations. As we know, the connections between the base station (BS) and mobile station (MS) may fail when the MS goes into a deep fading area. These variations will lead to lost connections and are harmful to mobile users who are using real-time applications such as video conferencing. We focused our study on the performance of different relay deployments under correlated shadow fading. We designed a cooperative communications scheme that allows MS to switch between different relay stations according to the channel conditions, and analyzed outage probability of the legacy scheme and our proposed scheme. Our simulation results show up to 65% reduction in the outage probability when 12 relay stations are present. The new design also significantly reduces the average duration of an outage event. After the relay density reaches 18, adding more relays does not significantly improves system performance. This research supported the development of technologies that achieve new levels of efficiency and quality in wireless broadband services, and will help alleviate the wireless bandwidth crunch being experienced by carriers. The impact could be far-reaching, including changing how global cellular standards are developed and standards contributions are compared.
