A Pipelined Cooperative Transmission Protocol for Fast and Reliable Image Delivery in Wireless Sensor Networks

Multimedia applications using wireless sensor networks often require bounds for end-to-end delay and packet loss rate in addition to energy efficiency in delivering a series of packets sliced from an image. This paper proposes a pipelined cooperative transmission (PCT) protocol for fast and reliable image delivery based on a tree topology originating from a sink, and allocation of a distinct time slot to each tree level. In this approach, if a sink needs an image from a specific multimedia node, it establishes a cooperative path such that a path node, a node on the tree path from the multimedia node to the sink, selects a cooperating node from its neighboring nodes at the same tree level. Then, the cooperating node assists its counterpart using the information obtained by means of overhearing message or data in order to forward a packet reliably to the nodes one level lower. This transmission mechanism improves the reliability of hop-by-hop transmission greatly without relying on retransmissions while making the packet move fast. Packets are transmitted in a pipelined manner using two channels such that different nodes at every other level send packets simultaneously. The proposed protocol is verified by analysis, simulation, and experiment, showing that it far outperforms the recent best approach in terms of end-to-end delay and energy consumption while achieving a high packet delivery rate.