Sensor networks and applications thereof have been intensively researched in the past decade and a variety of systems have been meanwhile deployed in real-world settings. Most of these applications and the corresponding sensor networks they use are designed as vertically integrated systems. In such vertical systems, a sensor network or a limited set of mostly homogeneous sensor networks are deployed for a specific application in mind. The application is mostly the sole user of this sensor network and has a priori knowledge of the capabilities that the sensor network(s) provides. An application also typically knows how to address the respective gateways/ sinks of the sensor networks, in order to interact with the sensor networks and shares a common interaction protocol with them.
As the number of the sensor networks that may be used by an application grows, it is becoming increasingly cumbersome for applications to manage direct interactions between those. Furthermore, the reuse of the existing sensor network infrastructure for multiple applications could avoid redundant deployment of similar sensor networks at the same location and provide higher returns for the initial investments costs of the deployed sensor network infrastructure. Recent research has therefore focused on overcoming the inflexibility of the tightly coupled vertical system and proposed several sensor network integration frameworks. These frameworks aim to break up the vertical systems into horizontal reusable system components and make them available to a larger set of applications. The frameworks typically provide support functionality that significantly reduces the interaction complexity of applications and eases incremental deployment of new sensor networks. Via these frameworks, applications can gain access to a large variety of connected geographically distributed sensor networks.
While representing first stepping stones for a real-world Internet, a variety of different issues remain unaddressed whereas they are essential for realizing an ecosystem for real-world contexts and interactions. Therefore, the development of sensor network integration frameworks is currently being carried by many industrial and academic institutions. In this chapter, an overview of existing sensor network integration frameworks (SNIFs) is presented, highlighting the main concepts and key features. Various examples of these frameworks are provided covering different design approaches from both industrial and academic organizations. Each of these frameworks is briefly analyzed with the description of key features and innovative solutions. Also their potential limitations and shortcomings are highlighted.
Recent technological developments in embedded systems have led to the emergence of a new class of networks, known as Wireless Sensor Networks (WSNs), where individual nodes cooperate wirelessly with each other with the goal of sensing and interacting with the environment. Routing has a significant influence on the overall WSN lifetime, and providing an energy efficient routing protocol remains an open problem. This thesis addresses the issue of designing WSN routing methods that feature energy efficiency. This book presents novel cross-layer routing algorithms. It also investigates the impact of the hop distance on network lifetime and proposes a method of determining the optimal location of the relay node. The problem of predicting the transition region (the zone separating the region where all packets can be received and that where no data can be received) is also addressed. The performance of described solutions was tested in simulations and also they were deployed on sensor nodes using TinyOS. All proposed schemes extend the network lifetime and due to their lightweight architecture they are very efficient WSN nodes with constrained resources.