Broadcast Scheduling Based on Network Coding in Time Critical Wireless Networks

Using network coding in wireless networks can increase throughput and reduce energy consumption. Recently there are many works focusing on how to utilize network coding to increase throughput, however there are few works considering the quality of service such as delay which is important to time critical applications. This paper focuses on network coding based broadcast scheduling problem in time critical wireless networks with packet delay constraint and aims at minimizing the number of packets which miss their deadlines. Using a weighted graph model, we formulate the problem with an integer linear programming and prove that it is NP-hard. By assigning vertex weight as a decreasing function of packet deadline, we propose a packet encoding and broadcasting algorithm based on the maximum weight clique in the graph. Detailed analysis shows that some typical application requirements can be realized with different weight functions, which can be useful for Qos design. Simulation results show that our algorithm significantly reduce the deadline miss ratio in most cases, which is an important performance metric in time critical applications.