Balanced Cooperative Linear Data Exchange with Physical Layer Network Coding

In this paper, we consider a group of nearby wireless end devices such as mobile phones cooperating to exchange their received packets from a common base station in order to fulfill the lost packets in other members. This problem can be solved by the linear coding in which each client transmits linear combinations of the received packets to minimize total number of transmissions. As the end devices have the limited energy resources, fairness should be a desirable property for each of them to support each other until all members in the group satisfy their needs. We introduce a cooperative algorithm that will maintain the fairness among nodes by distributing the number of transmissions they make. In this algorithm, each client changes the role of transmitter and receiver based on the information they keep in each round of data transmission. Moreover, we also incorporate physical layer network coding into this problem domain in order to further reduce the required transmission time slots and accomplish the data exchange process as quickly as possible.