Delay Minimization for Network Coded Cooperative Data Exchange with Rate Adaptation

In this paper, we dynamically select the transmission rates to reduce the transmission delay required for network coded cooperative data exchange. With low transmission rate, more clients can receive the packet due to longer transmission range. However, low transmission rate may incur extra transmission delay. We consider a delay minimization with rate selection and network coding (DMRSNC) for cooperative data exchange problem under two cases: with and without packet splitting. We construct a network information flow graph to model such a problem, and design transmission strategy with the aim of minimizing transmission delay. With packet splitting, the DMRSNC problem can be formulated as a linear programming based on the graph model, which can be solved in polynomial time. When the packet splitting is not allowed, we derive an upper bound for the minimum total transmission delay required for DMRSNC problem. In addition, we derive that the upper bound is at most three times of the optimal solution in a special case. Finally, the simulation results demonstrate the superiority of the proposed scheme in reducing the total transmission delay.