|Speaker:||Dr. Michael J. Neely, University of Southern California|
We consider the problem of communicating data from multiple traffic streams over an ad-hoc wireless network with time varying channels, user mobility, and possible transmission errors. Our network model is well suited for stochastic environments where exact channel conditions are difficult to assess, such as underwater networks of acoustic transmitters (where ocean dynamics and large delays create channel uncertainty), and land networks with mobility (where knowledge of which receivers are currently within transmission range may be uncertain). To communicate in these extreme environments, we exploit the broadcast advantage of wireless networks. Specifically, a single transmission might be overheard by a set of potential receivers. This creates a natural multi-receiver diversity gain, where the probability that at least one node successfully receives the transmission can be much larger than the success probability of any pre-specified receiver. To fully exploit the multi-receiver diversity gain, network routing algorithms must be designed with the flexibility of dynamically adjusting routing decisions after each packet is transmitted. This functionality affects network design at all networking layers, and is a hot topic of current research. In this talk, we present novel cross-layer control algorithms for routing, resource allocation, and flow control, with the goal of optimizing performance metrics of throughput, fairness, and power expenditure. A simple distributed flow control and routing algorithm DIVBAR (Diversity Backpressure Routing) is introduced and shown to achieve optimality subject to a given multiple access structure. The challenge of choosing a good multiple access structure is also discussed. Simulations of basic and enhanced versions of DIVBAR are also provided to illustrate the performance gains over existing algorithms.
Michael J. Neely received B.S. degrees in both Electrical Engineering and Mathematics from the University of Maryland, College Park, in 1997. He was then awarded a 3 year Department of Defense NDSEG Fellowship for graduate study at the Massachusetts Institute of Technology, where he received an M.S. degree in 1999 and a Ph.D. in 2003, both in Electrical Engineering.
|Presented On:||Nov 17th, 2006|
|Video:||QuickTime Streaming video|