Preface to the Special Issue

This is Part II of the special issue, entitled “Internet of Things,” of the ACM Transactions on CyberPhysical Systems. The special issue is presented to commemorate the 10th anniversary of the CPS research program and the inauguration of ACM Transactions on Cyber-Physical Systems. A total of 14 papers have been accepted for this special issue. Part I contains seven articles and here in Part II we present the remaining seven papers. Given the technical requirements of cyberphysical systems, many mission-critical applications need to perform computations at the edge of Internet of Things (IoT). The papers entitled “CHARIOT: Goal-Driven Orchestration Middleware for Resilient IoT Systems” and “Distributed Trade-Based Edge Device Management in Multi-Gateway IoT” address how to manage edging computation in IoT systems. Sensing is a critical function for IoT. The paper entitled “A Survey of Mobile Crowd Sensing Techniques: A Critical Component for the Internet of Things” reviews the state of this area and discusses its future directions. Given the operational nature of cyber-physical systems, the IoT must meet various stringent requirements of CPS applications (e.g., privacy, security, timing correctness, localization) at all layers. Articles dealing with this aspect at higher layers have been presented in Part I. Here, we present papers that deal with the problems at lower layers. The issues related to localization and time synchronization are addressed by the paper entitled “SLATS: Simultaneous Localization and Time Synchronization,” while power for wearable devices is the focus of the paper entitled “Toward Battery-Free Wearable Devices: The Synergy between Two Feet.” The security and safety issues are addressed, respectively, by the papers entitled “Feature-Driven Mediator Synthesis: Supporting Collaborative Security in the Internet of Things” and “Systematically Ensuring the Confidence of Real-Time Home Automation IoT Systems.” Through the papers we present here and many other scholarly works and industrial developments, we have many good reasons to celebrate the 10+ years of accomplishments made by the CPS (including IoT) community. However, at the same time, we also observe that some critical issues have not been thoroughly addressed. For example, in the call-for-proposal for this special issue [1], one of the topics listed was “Addressing, naming, and search technologies for the IoT.” Unfortunately, almost none of the submitted papers had seriously addressed this issue and none of the papers were accepted for the topic. In general, Studies on CPS (including IoT) is becoming an academic discipline which is critical for not only industrial technologies but also a new generation of workforce. To achieve this important goal, the community at large must jointly address several important and related issues: