## 6 SSNs Projects  
Many projects envisioned the utilization of SSNs by multiple concurrent applications, which tells us the importance of its role towards the IoT revolution. Each project has its own way to treat the challenges that are faced by this type of emerging shared network. Table 5 summarizes the characteristics for presented projects. 1. [leftmargin=*]
2. **FRESNEL**[89]: Federated Secure Sensor Network Laboratory is part of an academic research provided by Oxford internet institute in cooperation with Computer Laboratory (University of Cambridge) and Oxford University Computing Laboratory (ComLab). It focused on building a large scale federated sensor network framework, which supports concurrent applications running on the same infrastructure while also ensuring the reliability of intra-application communication as well as the scalability of distributed management infrastructure. It also maintains orthogonality, privacy, and security. The used sensors sense many environmental phenomena, like temperature, pollution, movement, etc., and the network will be running multiple applications of multiple authorities in the city of deployment. There are many research objectives to achieve the project goals described briefly, as follows: * Developing a language for service level description and an agreement for this emerging type of shared sensor networks, this language will be the base for resource sharing, application management, and monitoring framework. * Developing new techniques for dynamic resource allocation are decentralized solutions, these techniques will be developed according to the applications and they will vary according to its needs based on available network resources. * Identifying the mechanisms for dynamitic partitioning of the physical network into application-specific virtual sensor networks. During the phase of dynamic partitioning/repartitioning, these mechanisms must protect different application's nodes against each other, for privacy preservation and the observation of resource allocation boundary issues. * Developing devise distributed and scalable communication protocols, to allow for reliable and efficient communication among sensor applications. * Developing distributed algorithms for processing concurrent queries with very different quality-of-service requirements for accuracy and delay. These algorithms should be able to give priority to degrading the quality of the query; by this way, they can handle the needs of critical applications. * Deploying a prototype of federated sensor networks across the campus of the University of Cambridge, which partly integrate with existing sensor networks. This prototype will cover the needs of heterogeneous monitoring, which range from room usage and college security to air quality and traffic monitoring. 3. **Virtual Sensor Networks (VSNs)**[63]: is a project for a self-organizing scheme on the top of a cluster tree in VSNs based on a subsurface chemical plume monitoring system, this project is provided by Computer Networking Research Laboratory by Colorado State University. The project team concentrated on cluster tree random routing, virtual coordinates, and VSN support functions. As VSNs are an emerging form of collaborative WSNs, it can support collaborative, resource efficient, and multi-purpose WSNs. The VSNs are created by a subset of sensor nodes/users that dynamically vary based on the migration between the available resources and application requirements. This project is useful in three types of applications: the first is Geographically overlapped applications, like monitoring rock slides and animal crossing within a mountainous terrain; the second is logically separated multi-purpose sensor networks, like smart neighborhood systems with multifunctional sensor nodes; and, the third are certain dedicated applications, such as those that enhance the efficiency of a system by tracking a dynamic phenomena, such as subsurface chemical plumes that migrate, split, or merge.