A survey of Wireless Sensor Network technologies: research trends and middleware's role

Wireless Sensor Networks (WSNs) provide a new paradigm for sensing and disseminating information from various environments, with the potential to serve many and diverse applications. Current WSNs typically communicate directly with a centralized controller or satellite. On the other hand, a smart WSN consists of a number of sensors spread across a geographical area; each sensor has wireless communication capability and sufficient intelligence for signal processing and networking of the data. The structure of WSNs are tightly application-dependent, and many services are also dependent on application semantics (e.g. application-specific data processing combined with data routing). Thus, there is no single typical WSN application, and dependency on applications is higher than in traditional distributed applications. The application/middleware layer must provide functions that create effective new capabilities for efficient extraction, manipulation, transport, and representation of information derived from sensor data. In this paper, we report recent trends in wireless sensor network research including an overview of the various categories of WSN, a survey of WSN technologies and a discussion of existing research prototypes and industry applications. We focus on middleware technology, and describe details of some existing research prototypes, then address challenges and future perspectives on the middleware. This study highlights that middleware needs to provide a common interface for various functional components of WSN: detection and data collection, signal processing, data aggregation, and notification. By integrating sensing, signal processing, and communication functions, a WSN provides a natural platform for hierarchical information processing.