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Practical network coding by binary superposition of codewords...

SPEAKER: Professor Joerg Kliewer, University of Notre DameABSTRACT: In this talk we consider two applications of network coding based on the binary superposition of codewords at a network node. In the first application we address the scenario in which two partners (node A and node B) cooperate in transmitting information to a single destination; each partner transmits both locally-generated information and information that originated at the other partner. A key observation is that node B already knows node A's relayed information and can exploit that knowledge when decoding node A's information. This leads to an encoding scheme in which each partner transmits the binary superposition of its local and relayed information. The superimposed codeword is interpreted differently at the two receivers, i.e., at the other partner and the destination node, based on their different a priori knowledge. Simulation results show that the proposed scheme provides substantial coding gain over other cooperative diversity techniques.The second application proposes a novel distributed encoding procedure to realize codes that resemble LT codes (rateless codes for erasure correction) in both structure and performance. For the case of two sources communicating with a single sink via a common relay, this technique separately encodes K/2 symbols of information onto slightly more than K code symbols at each source. These two codewords are combined at the relay by a mixture of routing and network coding. The resulting MLT (modified LT) code can then be decoded by the sink to recover all K information symbols. It is shown that, for the case of four sources communicating to a single sink, using a MLT code leads to a 50% reduction in overhead at the sink, compared to employing four individual LT codes combined by time-sharing at the relay. Similar benefits for MLT codes can also be observed for the frame error rate if a fixed code rate is considered.Bio: Joerg Kliewer received the Diploma Degree (M.S.) in Electrical Engineering from the Hamburg University of Technology, Hamburg, Germany, in 1993 and the Dr.-Ing. degree (Ph.D.) in Electrical Engineering from the University of Kiel, Kiel, Germany, in 1999, respectively. From 1994 to 1998 he was a research assistant at the University of Kiel, Germany. From 1999 to 2004 he was with the Faculty of Engineering, University of Kiel, Germany, as an Assistant Professor. In 2004 he was visiting the University of Southampton, U.K., for one year, and since 2005 he is with the University of Notre Dame, IN, as a Visiting Assistant Professor. He received a Leverhulme fellowship award in 2003 and a German Research Foundation fellowship award in 2004, respectively. His current research interests include joint source and channel coding, error correcting codes, network coding, and network information theory.Host: Keith Chugg, chugg@usc.edu

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Mayumi Thrasher