On the Network Coding-Based D2D Cooperative Recovery for Lossy Feedback-Free Broadcasting

This letter investigates the cooperation issue between two adjacent user nodes that can mutually recover the lost packets in a lossy wireless broadcast system by maintaining a device-to-device (D2D) communication pair. Unlike existing studies, we consider a feedback-free transmission model where the broadcast source node does not receive the reception status and channel conditions from its user nodes, and neither does it dynamically adjust its broadcast content. We model such best-effort content delivery scenario with a time-slotted system and propose a Network Coding based D2D Cooperative recovery scheme (NC2) to schedule the cooperation process between user nodes. NC2 maximizes the packet receiving reliability of the two user nodes by utilizing an adaptive coding window sliding strategy and proper transmission procedure. NC2 also considers the practical situation, such as the limited user device buffer size and the decoding latency of source packets. Theoretical bounds of the reliability and decoding delay of NC2 have been analyzed. Numerical results also validate the effectiveness and efficiency of the proposed scheme.