The coordination and tight link between computational and physical resources change the way in which society interacts with the physical world. Cyber-physical system (CPS) integrates the dynamics of the physical processes with those of software and networking, providing abstractions and modelling, design and analysis techniques for the integrated whole. Examples of CPSs are abundant in our everyday life, including intelligent built environment, intelligent transportation, intelligent infrastructures in which massive interconnected sensors, actuators, controllers and other smart devices are embedded. The special issue of International Journal of Parallel, Emergent and Distributed Systems on CPS is to provide a set of recent practice of developing such systems.
The paper ‘An indoor location tracking system for smart parking’ by Kun-Chan Lan and Wen-Yuah Shih investigates how to detect unparking events that can be used by people looking for parking space. It is an important problem since searching for street parking in a crowded urban area imposes societal and environmental challenges. The basic idea is to track the walking trajectory of drivers by utilising the capacity of sensors, e.g. GPS, accelerometer, gyro and digital compass, in their smart phones. The authors implement a waist-mounted method on a smart phone that can measure the moving distance with high accuracy. In particular, a map matching algorithm is proposed to calibrate direction errors from the gyro using building floor plans.
Smart grid technology has been emerging as the next-generation intelligent power grid system and power industries have already adopted smart grid technology along their daily business operations. The following three papers investigate the security and privacy issues in smart grids.
The paper ‘New hypothesis testing-based rapid change detection for power grid system monitoring’ by Qian He and Rick S. Blum considers fault detection of electrical power grid systems. They are motivated by the factor that power grid systems are vulnerable to malicious attacks that can change state estimation results arbitrarily without being caught by traditional bad measurement detection techniques. To deal with intrusion detection of the monitored power grid system, a new hypothesis testing method, called LOUD (locally optimum unknown direction), is developed with a desired feature that it is able to produce decisions right after the change has occurred without waiting to collect additional data. The numerical results also show that LOUD performs nearly as good as the optimum.
The paper ‘Secure and threshold-based power usage control in smart grid environments’ by Bharath K. Samanthula, Hu Chun, Wei Jiang and Bruce M. McMillin reconsiders the threshold-based power usage control problem by focusing on the privacy and security issues. To improve the existing solutions that reveal intermediate results, such as average and maximum power usage, this paper proposes efficient solutions to the basic security primitives, namely secure binary conversion, comparison, maximum and division operations. The practical value of the proposed protocols is also shown through various experiments.
The paper ‘No peeking: privacy-preserving demand response system in smart grids’ by Depeng Lia, Zeyar Aungb, John R. Williams and Abel Sanchez studies the privacy issue in the demand response (DR) programs that are widely used to balance the supply and demand of electricity in a smart grid. Without a well-designed privacy preservation mechanism, power usage and operational data can be abused to infer personal information of customers. This paper proposed an attributed-based encryption protocol for various DR programs on an emulated smart grid platform. The experimental results show substantially lighter overheads while formidable privacy challenges are addressed.
The high quality of information transmission in mobile CPSs mainly relies on the assumption that nodes are willing to participate in the forwarding service. As a result, uncooperative behaviours of selfish nodes may degrade network performance greatly. The last paper ‘A novel hybrid incentive mechanism for node cooperation in mobile cyber-physical systems’ by Xiaofei Wang, Ying Cai and Zhuo Li studies how reputation and credit can stimulate cooperation in a mobile CPS. An incentive solution named reputation-based credit mechanism (RCM) is proposed by taking resource consumption and forwarding quality into consideration. Simulation results show that RCM outperforms both reputation-based and credit-based solutions.
Finally, the guest editor would like to express his sincere gratitude to the Editor-in-Chief, Professor Ivan Stojmenovic, of International Journal of Parallel, Emergent and Distributed Systems for providing this opportunity and lots of guidance throughout the process. The guest editor also wishes to thank both the authors and the reviewers for their hard work in helping assemble this special issue.