Sharing information in time-division duplexing channels: A network coding approach

We study random linear network coding for time-division duplexing channels for sharing information between nodes. We assume a packet erasure channel with nodes that cannot transmit and receive information simultaneously. Each node will act as both a sender of its own information and a receiver for the information of the other nodes. When a node acts as the sender, it transmits coded data packets back-to-back before stopping to wait for the receivers to acknowledge the number of degrees of freedom, if any, that are required to decode correctly the information. This acknowledgment comes in the header of the coded packets that are sent by the other nodes. We study the mean time to complete the sharing process between the nodes. We provide a simple algorithm to compute the number of coded packets to be sent back-to-back depending on the state of the system. We present numerical results for the case of two nodes sharing data and show that the mean completion time of our scheme is close to the performance of a full duplex network coding scheme and can outperform full duplex schemes with no coding.