Opportunistic Network Coding

Abstract

In this chapter we describe a practical view of the usage of the network coding theory over realistic communication networks. In particular, we introduce opportunistic network coding, which can be applied to wireless networks with mesh topologies and multiple unicast streams. With the term opportunistic we describe the opportunistic nature of this type of coding, as packets are encoded only if the opportunity arises and there are no mechanisms within it to increase the number of coding opportunities. Different coding approaches have been proposed that cover different network configurations and traffic patterns. In particular, we focused on the main design aspects of BON and COPE, the two opportunistic network coding procedures that perform network coding on the packet level and can significantly improve the network throughput. In addition, we are also describing performance metrics, which are found suitable for performance evaluation of network coding algorithms. For illustration purposes we also show typical results for the above mentioned algorithms. The results show that opportunistic network coding can significantly improve the wireless mesh network performance in terms of throughput and delay.