## 1 Introduction  
Technological advancement in semiconductor design, material sciences and networking are driving the ubiquitous deployment of large scale wireless sensor and actuator networks [1]. Today, these technologies have merged to enable Wireless Sensor Networks (WSNs) that can provide low-cost, low power, multifunctional miniature devices with interfaces to connect with a multitude of sensors [2]. These devices can gather sensed information from the environment and communicate it in an untethered manner over a short distance that can be further routed by means of multi-hop to a central monitoring station. Applications of WSN have now found their way into the work place, home and environment enabling more user control and convenience. Significant research contributions have also made WSN communication more reliable for real time scenarios paving way for a well-established mix of software and hardware solutions in future applications [1]. With maturity in WSN protocols, researchers have started looking into extended functionality for interaction with other network systems using reliable and secure methods. Cyber Physical Systems (CPS) principles are thus finding their way into sensing applications as a platform to provide extended interactive functionality between real time and virtual environments. CPS provides an intuitive interconnection mechanism for human-to-human, human-to-machine and machine-to-machine interactions through the facilitation of seamless network connectivity and refined user control over actuation side [3]. By definition, CPS is meant to provide a virtual environment that incorporates an interacting network of system elements with physical inputs and outputs at both ends (Figure 1). A WSN enabled with CPS can provide remote control over the network devices with scattered network elements instead of a standalone system [4, 5]. Currently, only a vague interface portfolio exists to identify the overlapping areas of CPS and WSN where both can be seamlessly integrated. There is therefore a need to define clearly as to where the communication layers for WSN and CPS would connect and how to overcome the challenges in making both platforms compatible. With monitoring of oil and gas transfer installations using WSN and CPS as the main focus, we link real world challenges and industrial practices to provide a concise technical summary as to where cyber physical and sensor network mergers would stand in the future and directions to meet the requirements. With a concise summary of WSN and CPS platforms, oil and gas pipeline infrastructure health monitoring as well as environmental- and fluid condition-related reliability requirements are explained. The rest of the paper is arranged as follows: In Section 2, CPS based sensor network deployment is highlighted. In Section 3, Quality of Service (QoS) parameters in Cyber Physical Sensor Networks (CPSN) is explained. Section 4 deals with reliability and prediction design requirements for CPSN architecture. Section 5 is dedicated to integrating platforms, protocols and applications for CPSN, followed by a case study on oil and gas pipeline monitoring application in Section 6. Finally, Section 7 concludes the paper with a summary of CPSN for infrastructure monitoring. WSNs have gained importance in recent years due to the proliferation of Micro-Electro-Mechanical Systems (MEMS) technology facilitating the fabrication of Smart Sensors. The miniature sized sensors with limited computing power can sense, gather information and measure several environment parameters and, based on the local decision, forward it to a base station. Though battery is the main source of power for these devices, recent techniques have started to focus on energy harvesting from natural resources like wind, solar energy and natural vibrations. A typical WSN has little or no infrastructure and consists of numerous sensor nodes laid out over the monitoring area that gather data over time.