Improving response time in time critical Visual Sensor Network applications

Wireless sensor network (WSN) consisting of nodes equipped with cameras or advanced low-cost image sensors is known as a Visual Sensor Network (VSN). The main function of VSN is to capture images and send them to sink nodes for processing. Common applications of a VSN are surveillance, tracking, crowd management, scientific research, etc. Such applications require large amounts of data to be exchanged between camera nodes and sink. Image data is considerably larger than common sensor data such as temperature, humidity, and pressure. For data delivery in VSNs, the communication is constrained by many stringent QoS requirements like delay, jitter and data reliability. Moreover, due to the inherent constraints of WSN such as limited energy, low CPU power, and insufficient memory; the architect of VSN must choose appropriate topology, image compression algorithms, and communication protocols depending on application. In literature, different techniques have been proposed to resolve the bandwidth requirements for the VSN. The majority of these techniques are based on the compression of visual data. This paper focuses on one of these aspects, namely the communication protocol for VSN. In this paper, we present Priority Routing Framework for Image Transmission (PRoFIT), a new routing framework for VSN to deliver critical imagery information with system's time constraint. We demonstrate that PRoFIT improves response time in various VSN applications as compared to priority-less routing techniques. We have implemented PRoFIT along with an image processing application using Contiki and simulated it on Cooja simulator to support our claim.