Supporting Delay-Sensitive Applications in Next-Generation Wireless Networks --- A New Theory Combining Large Deviations with Lyapunov Stability
The trend of wireless communication networks is to move towards fully packet-basedwireless networks that can support both data applications and high-rate delay-sensitiveapplications. The key to the success of such networks is to be able to provide thestringent delay guarantees that delay-sensitive applications require, and to maximize thecapacity of the system at the same time. Unfortunately, analyzing delay-performance andproviding delay-guarantees in wireless networks have long been a very difficult problemdue to both the scarcity of the wireless resources and the unpredictablechannel-variation.
In this talk, we focus on using large-deviations theory to study the delay- and queueing-performance of wireless networks operating under queue-length-based schedulingalgorithms. Although large-deviations theory allows us to focus on the (simpler)asymptotic regime with small queue-overflow probabilities, it still leads to a complexmulti-dimensional calculus-of-variations problem that is very difficult to solve. Hence,analyzing the large-deviations delay-performance and optimality remains a difficultchallenge. In our recent work, we develop a new theory that combines large deviationswith Lyapunov stability to circumvent this difficult. We show that if a control policyminimizes the drift of a Lypaunov function, then the policy is optimal for maximizing thelarge-deviations decay-rate of the overflow probability that corresponds to largeLyapunov function values. We will demonstrate how this result can be applied to bothpacket-based cellular networks and multi-hop wireless networks to easily draw conclusionson the delay-performance of existing wireless control policies, and to design newdelay-optimal control algorithms.
Xiaojun Lin received his B.S. from Zhongshan University, Guangzhou, China, in 1994, andhis M.S. and Ph.D. degrees from Purdue University, West Lafayette, Indiana, in 2000 and2005, respectively. He is currently an Assistant Professor of Electrical and ComputerEngineering at Purdue University.
Dr. Lin's research interests are in the analysis, control and optimization of large andcomplex wireless and wireline networks. He received the IEEE INFOCOM 2008 best paperaward and 2005 best paper of the year award from Journal of Communications and Networks. His paper was also one of two runner-up papers for the best-paper award at IEEE INFOCOM2005. He received the NSF CAREER award in 2007. He was the Workshop co-chair for IEEEGLOBECOM 2007, the Panel co-chair for WICON 2008, and the TPC co-chair for ACM MobiHoc2009.