Rate-aware network codes for completion time reduction in device-to-device communications

In this paper, we consider a fully connected device-to-device communications network, where a group of devices with heterogeneous channel capacities cooperate with each other to recover their missing packets. In such cooperative network, we aim to minimize the completion time required for recovering all missing packets at devices using instantly decodable network coding (IDNC). In particular, we first introduce a new IDNC graph to represent all feasible rate and coding decisions for all potential transmitting devices in one unified framework. We then show that finding the optimal schedule that minimizes the completion time is computationally complex. Nevertheless by using the new graph and the properties of the optimal schedule, we design a completion time reduction heuristic that balances between the transmission rate and the number of targeted devices with a new packet. Simulation results show that our proposed IDNC algorithm provides an appreciable completion time gain compared to the conventional rate oblivious network coding algorithms.