Wireless Network Coding

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• Jan Sykora, Czech Technical University in Prague
• Thursday 23 September 2010, 14:00-15:00
• Room 503.

If you have a question about this talk, please contact Cong Ling.

It is becoming widely accepted that the most significant future developments in the physical layer of wireless communication systems will not take place in the PHY layer of individual communication links, but rather in the context of complete wireless networks. Over the past decade or so there have been significant developments in network information theory which have shown that very significant overall performance gains are available compared to the conventional paradigm in which PHY techniques are applied to individual links only, leaving network aspects to be dealt with only at higher layers of the protocol stack. One such new research field is network coding, in which coding techniques are applied to multiple data streams at intermediate nodes in a network, rather than only to individual streams on single links. This can exploit network topology to significantly improve throughput in multiuser networks. However in its original form it operates at the level of data streams, rather than signal waveforms, and hence is not well suited to the inherently broadcast nature of wireless networks. Physical layer or wireless network coding (WNC) allows it to be applied directly to wireless networks, with a further significant improvement in efficiency. The key advance on conventional PHY techniques is that both signalling waveforms and node signal processing is aware of the network topology and exploits it to improve overall network throughput.

The talk will first introduce wireless network coding in the context of network information theory and the network-aware PHY layer. It will then introduce some of the basic principles and strategies of WNC , for example the strategies of hierarchical decode/compress and forward which replace the amplify/decode and forward strategies of conventional relaying, and consider the network capacity regions that result. The potential benefit will be put into a context of some practical applications.

The second part will focus on an important example scenario: the two-source relay channel (2S-RC) in which two sources simultaneously exchange information with two destinations with the aid of a single relay, which may frequently occur in a wireless access network. It will describe code design for this scenario, and the effect of fading parameters on performance. In doing so it will introduce a fundamental principle which allows separation between an inner hierarchical exclusive alphabet and an outer error control code, which can be a conventional binary capacity-approaching code such as a turbo or LDPC code.

In the last part, we demonstrate some open problems and recent advances in the Hierarchical Decode & Forward Strategy for network aware PHY layer.

Bio: Jan Sykora (Jan.Sykora@fel.cvut.cz, http://radio.feld.cvut.cz/~sykora) received the M.Sc. and Ph.D. degrees in Electrical Engineering from Czech Technical University in Prague, Czech Republic, in 1987 and 1993, respectively. Since 1991, he has been with the Faculty of Electrical Engineering, Czech Technical University in Prague, where he is now a Professor of Radio Engineering.

His research includes work on wireless communication and information theory, cooperative and distributed modulation, wireless network coding and distributed signal processing, MIMO systems, nonlinear space–time modulation and coding, and iterative processing. He has served on various IEEE conferences as a Technical Program and Organizing Committee member and chair. He has led a number of industrial and research projects financed by EU and national agencies.

This talk is part of the COMMSP Seminar series.

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