Intelligent EPD for RTP-based Video Streaming over Multi-hop Ad Hoc Networks

摘要

This paper presents an intelligent early packet discard (I-EPD) for RTP-based video streaming over a multi-hop MANET (Mobile ad hoc network). In a multi-hop MANET, the quality of transferring real-time video streams could be seriously degraded, since every intermediate node (IN) functionally like forwarding device does not possess large buffer and sufficient bandwidth. Even worse, a selected forwarding node could leave or power off unexpectedly which breaks the route to destination. Thus, a video packet temporarily buffered in ad hoc nodes may exceed its end-to-end jitter constraint when either a congested or failed link occurs; a stale video packet is useless even if it can reach destination after network traffic becomes smooth or failed route is reconfigured. In the proposed I-EPD, an IN can intelligently determine whether a buffered video packet should be discarded based on an estimated time constraint which is calculated from the RTP timestamps and the round trip time (RTT) measured by RTCP. For the purpose of validation, we implement the I-EPD scheme on a Linux-based embedded system to demonstrate that with I-EPD buffer utilization on IN can be more effective and unnecessary bandwidth wastage can be avoided.