Opportunistic Routing in Wireless Multihop Networks
Speaker: Professor Tara Javidi
Faculty Host: Professor Elza Erkip
Opportunistic routing for multi-hop wireless networks has seen recent research interest to overcome deficiencies of traditional routing. Specifically, the routing decisions are made opportunistically, choosing the next relay based on the actual transmission outcomes in addition to an expected sense of future opportunities. First, we, briefly, cast opportunistic routing as a Markov decision problem (MDP) and introduce as a unifying stochastic framework for almost all versions of opportunistic routing such as SDF, GeRaF, and EXOR.
In the second part of the talk, we touch upon the issue of congestion and throughput optimality by contrasting the opportunistic MDP-based schemes with opportunistic versions of back-pressure routing. We propose combining the approaches to arrive at a throughput-optimal policy, Opportunistic Routing with Congestion Diversity (ORCD), that exhibits significant delay improvements over the existing candidates in the literature. We also make connections to various delay optimal routing solutions in literature. In the final part of the talk, we briefly discuss practical issues arising in the context of opportunistic routing: cross-layer issues (MAC, network, and transport layers), implementation on off-the-shelf 802.11 radios, ACK explosion, and overhead versus performance trade-off.
About the Speaker
Tara Javidi studied electrical engineering at Sharif University of Technology, Tehran, Iran from 1992 to 1996. She received the MS degrees in electrical engineering (systems), and in applied mathematics (stochastics) from the University of Michigan, Ann Arbor, in 1998 and 1999, respectively. She received her PhD in electrical engineering and computer science from the University of Michigan, Ann Arbor, in 2002.
From 2002 to 2004, she was an assistant professor at the Electrical Engineering Department, University of Washington, Seattle. She joined University of California, San Diego, in 2005, where she is currently an associate professor of electrical and computer engineering.
Tara Javidi was a Barbour Scholar during 1999-2000 academic year and received an NSF CAREER Award in 2004. Her research interests are in communication networks, stochastic resource allocation, stochastic control theory, and wireless communications.