Modeling the transmission of coded packets for coding aware routing

This paper analyzes the process of sending a coded packet in the wireless medium. Understanding this basic network coding operation is fundamental for the recent work on coding aware routing. Unlike the transmission of a native (not coded) packet, a coded packet can be partially received, i.e., received by only a subset of its intended receivers. The literature on this subject has relied on strong assumptions to simplify the models for evaluating routes. Specifically, most works adopt the hypothesis of independence between the events of reception by different receivers. In this paper we present theoretical arguments and experimental results that show this hypothesis is not valid in practical cases. To overcome this issue, we present a simple, yet effective, method for estimating the joint reception probability for a coded packet. We also discuss the mechanisms that are used in the literature to implement the operation of transmitting a coded packet to a group of receivers and conclude that they are still inefficient. As a result of this analyses, we propose a new mechanism that maximizes the joint reception probability of the packet. Our experimental results show that this novel mechanism outperforms other commonly used techniques.