How Many Packets Can We Encode? - An Analysis of Practical Wireless Network Coding

While the practical coding scheme has been shown to be able to improve throughput of wireless networks, there still lacks fundamental understanding on how the coding scheme works under realistic settings, namely, when it operates on a realistic physical layer and the medium access is controlled by some random access methods. In this paper, we provide a formal analysis on the performance of the practical coding scheme under such realistic settings. The key performance measure is the encoding number, i.e., the number of packets that can be encoded by a coding node in each transmission. We provide an upper bound on the encoding number for the general coding topology, and derive the average encoding number and system throughput for a general class of random access mechanisms. Based on the practical coding scheme, we also derive a tighter upper bound on the throughput gain for a general wireless network. Our results can be particularly useful for coding-related MAC/Routing protocol design and analysis.