Deadline-aware broadcasting in wireless networks with network coding

Broadcasting with network coding mixes different packets to minimize the number of transmissions, which improves the energy efficiency of wireless networks. On the other hand, delaying the transmissions increases coding opportunities at the intermediate nodes, but increases the delay of the packets. In this paper, we consider these two contradicting factors and study the problem of minimizing the number of transmissions in wireless networks while meeting the deadlines of different packets. We show that this problem is NP-complete; therefore, we provide a heuristic to solve the problem. First, we construct broadcasting trees, each of them rooted at one source. We then specify overlapping conditions based on the constructed trees to determine the number of transmissions each node has to perform without the deadline constraints. Then, we partition the set of packets such that coding is performed among the packets of the same partition, which does not result in deadline misses. Our simulation results show that our technique not only reduces the number of transmissions, but also allows the majority of the nodes to receive their packets on time.