Wireless Network Coding with Imperfect Overhearing

Not only is network coding essential to achieve the capacity of a single-session multicast network, it can also help to improve the throughput of wireless networks with multiple unicast sessions when overheard information is available. Most previous research aimed at realizing such improvement by using perfectly overheard information, while in practice, especially for wireless networks, overheard information is often imperfect. To date, it is unclear whether network coding should still be used in such situations with imperfect overhearing. In this paper, a simple but ubiquitous wireless network model with two unicast sessions is used to investigate this problem. From the diversity and multiplexing tradeoff perspective, it is proved that even when overheard information is imperfect, network coding can still help to improve the overall system performance. This result implies that network coding should be used actively regardless of the reception quality of overheard information. Index Terms Network coding, wireless overhearing, transmission strategy, diversity and multiplexing tradeoff. The work reported in this paper has formed part of the Flexible Networks area of the Core 5 Research Programme of the Virtual Center of Excellence in Mobile & Personal Communications, Mobile VCE, www.mobilevce.com, and has been jointly funded by Mobile VCE’s industrial member companies and the UK Government, via the Engineering and Physical Sciences Research Council. This work was published in part in the Second IEEE International Workshop on Wireless Network Coding (WiNC 2009), Rome, Italy, June 2009. The authors are with Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK (e-mail: [email protected]; [email protected]; [email protected]). March 24, 2010 DRAFT 2