## 3 Quality of Service Reliability in Cyber Physical Sensor Network  
QoS provisioning becomes a much complex task when the sensing plane of CPSN needs to address thousands of sensor nodes placed in various topologies [17]. These challenges need to be addressed on both sides of the gateway, _i.e._, the Internet Cloud side and the sensing plane. QoS design requirements for implementing a planned CPSN would include: (1) Service Oriented Architecture (SOA); (2) QoS aware communication and networking; (3) intelligent resource management; and (4) QoS aware power management at various communication levels (Open Systems Interconnection \"OSI\" layers) [17]. SOA plays an important role in reducing the complexity of the infrastructure by decomposing CPS functions into smaller distinguishable units each viewed as a separate service [18]. This allows rapid, efficient and scalable development of a CPS application through reusable service units. Application level QoS, however, needs to be defined according to the service for intelligent cross layered communication. With the future trends in user applications [19], CPSN environments would require dynamic system settings for unpredictable environments [20]. Self-management policies would be needed so that allocated resources like CPU time, bandwidth memory, energy profiles can be controlled intelligently in a high level QoS constrained system setup [21, 22]. A major concern with QoS provisioning also pertains to the minimization of energy consumption for major network elements. In this regard, Cloud Computing provides a possible solution wherein major enabling technologies for such a setup are Virtualization and Ubiquitous connectivity. Virtualization related technologies like Software Defined Networking (SDN) and virtual operating systems and connections allow provision of dynamically changing and altering resources based upon service isolation, thus enabling scaling and managing of resources in a more controlled way. Since the resources of the cloud connecting the sensing platform are dynamically manipulated, the cloud itself would provision the typical three types of services to the sensor platform on one side and the remote user on the other side. These services include SaaS (Software as a Service), PaaS (Platform as a Service) and IaaS (Infrastructure as a Service). SaaS provides services to remote users on a demand basis. PaaS provides a development environment that is encapsulated and offered to users as a service wherein higher level applications can work over it. Finally, IaaS is responsible for provisioning computing capabilities and basic storage as standardized services for both sides of the network. Once the sensing platforms run under a cloud, several differentiations can be made according to the sensing application in hand. Since integrating WSNs with the cloud makes it easy to share and analyze real  
Figure 5: Wireless sensor network parameters and issues related to mobility and reconfiguration in a cyber-physical environment. time sensor, further advantage can be taken by provisioning sensor data or sensor event as a service over the internet; hence, the terms Sensing as a Service (SaaS) and Sensor Event as a Service (SEaaS) are sometimes used. Some typical examples of protocols that could be implemented at different OSI layers for enabling CPSNs are mentioned in Table 3.  
Prediction of accurate output decisions and reliability of sensing information are considered critical for CPSN systems. There is therefore a need to define strictly the network requirement factors in terms of cyber and physical domains (Figure 6). These factors also form the QoS basis for achieving a real time intelligent system for high stress and constrained environments like mining, healthcare and warfare. QoS factors like seamless data flows through the cloud and timely delivery at the monitoring station are considered critical for cyber systems. This becomes more challenging when CPS is integrated with other technologies like semantic agents and hybrid system states in the Cloud.