Please note that Dr. Un-Ku Moon's talk has been cancelled. We have a talk at 10am today and Wednesday, in Owen 102. See below for outlines.
Monday April 25 10:00 - 10:50 AM Owen 102 Gang Cheng Ph.D. Candidate Electrical Engineering New Jersey Institute of Technology Quality-of-Service Provisioning in High Speed Networks: Routing Perspective The continuous growth in both commercial and public network traffic with various quality-of-service (QoS) requirements is calling for better service than the Internet's best effort mechanism. One of the challenging issues is to select feasible paths that satisfy the different requirements of various applications. This problem is known as QoS routing. In general, two issues are related to QoS routing: state distribution and routing strategy. Routing strategy is used to find a feasible path that meets the QoS requirements. State distribution addresses the issue of exchanging the state information throughout the network. In this talk, I will present a novel routing architecture which consists of two parts: rate-distortion analysis based link state update and a self-adaptive QoS routing algorithm. We first address the issue of updating link state information from the perspective of information theory. Based on the rate-distortion analysis, I will present an original scheme, which outperforms the state of the art in terms of both protocol overhead and accuracy of link state information. QoS routing is NP-complete. Hence, tackling this problem requires heuristic. A common approach is to convert this problem into a shortest path problem and solve it with existing algorithms, e.g., Bellman-Ford and Dijkstra algorithms. However, this approach suffers from either high computational complexity or low success ratio in finding the feasible paths. Hence, I will introduce a new problem, All Hops k-shortest path (AHKP). Based on the solution to AHKP, I will present efficient self-adaptive routing algorithms, which can guarantee in finding feasible paths with fairly low average computational complexity. One of their most distinguished properties is their progressive property, which is very useful in practice: they can self-adaptively minimize their computational complexity without sacrificing the performance. Wednesday April 27 10:00 - 10:50 AM Owen 102 Erik Perrins Ph.D. Candidate Electrical and Computer Engineering Brigham Young University Shaped-Offset QPSK: An Introduction with Coding Applications Shaped Offset QPSK (SOQPSK) is a highly bandwidth-efficient constant-envelope modulation. It is currently used in satellite and telemetry communications standards. In addition to its bandwidth-efficiency, SOQPSK is attractive because it can be demodulated with a generic symbol-by-symbol OQPSK-type detector. However, this simple and suboptimum approach does not exploit the inherent memory in SOQPSK, which is a type of continuous phase modulation (CPM). In this work, we develop a CPM signal model that accounts for all the memory in the SOQPSK system. This model gives an optimal trellis-based detector for SOQPSK and also allows it to be viewed as a code. We apply this technique to serially concatenated coding schemes with iterative detection, where SOQPSK itself constitutes the inner code. A number of reduced-complexity designs are presented. In particular, it is shown that all versions of SOQPSK, from the simplest to the most complex, can be treated with a simple, common architecture. Biography Erik Perrins is a graduating PhD student from the Department of Electrical and Computer Engineering at Brigham Young University. He also received his BS in 1997 and his MS in 1998 from BYU, both in electrical engineering. From 1998-2004 he was with the Advanced Technology Group of Motorola in Schaumburg, IL. Since 2004 he has been an industry consultant while concurrently finishing his studies at BYU. His research interests are digital transmission theory, modulation and coding, and signal processing. _______________________________________________ Colloquium mailing list [email protected] https://secure.engr.oregonstate.edu/mailman/listinfo/colloquium
