Improving Throughput of Video Streaming in Wireless Sensor Networks

Abstract

Wireless sensor networks are originally distributed event-based systems that differ from traditional communication networks in several ways. These networks typically have nodes with severe energy constraints, variable quality links, low data-rate and many-to-one event-to-sink flows. Recently, Wireless Multimedia Sensor Networks (WMSNs) have been developed with the availability of low-cost cameras, microphones, and other sensors producing multimedia data. The applications, accordingly, are extended to video surveillance and notification, video and computer assistance in living, etc. The stringent requirements of real-time multimedia applications include end-to-end delay, bandwidth and loss during data transmission. Communication algorithms for WMSN must therefore be specially designed to operate efficiently under these constraints. Directed diffusion is a data-centric protocol designed for wireless sensor networks. However, it is not efficient in more challenging domains, such as video sensor networks, because of inability to satisfy the throughput and delay requirements of multimedia data. Instead, we propose EDGE, a greedy algorithm based on directed diffusion that reinforces routes with high link quality and low latency,thus maximizing throughput and minimizing delay. ETX (Expected Transmission Count)is used as the metric for measuring link quality. And we present an improved method for computing aggregate ETX for a path that increases end-to-end throughput. Multiple-path is one of the ways how QoS routing issues are dealt with in wired environment. Besides, some existing ad hoc routing algorithms also provide multi-path routing. Directed diffusion has been commonly used for wireless sensor networks because of its energy efficiency and scalability. However, the basic protocol only routes packets through a single path, which barely meets the throughput requirement of multimedia data. Instead, we propose a multi-path algorithm based on directed diffusion that reinforces multiple routes with high link quality and low latency. In directed diffusion, many routing messages are propagated unnecessarily and may cause different interference characteristics during route discovery phase and in the actual application data transmission phase. We propose a routing protocol that uses ID-free epidemic flooding to limit interference in conjunction with metrics for increasing throughput and reducing delay.