Collaborative Research: Physical Dynamics Aware Coding for Communications in Cyber Physical Systems: Analysis, Algorithms and Implementation

Purdue University, West Lafayette IN

Investigators

Abstract

In recent years, there have been substantial researches on cyber physical systems. A typical cyber physical system is composed of both physical and cyber parts. The physical part refers to the dynamics ruled by physical laws, while the cyber part (which consists of sensor(s), communication and controller(s)) observes the physical dynamics, transmits the reports, and makes control actions. Many practical applications can be considered as cyber physical systems, such as smart grids, unmanned aerial vehicles, and robotic networks. The communication part plays a key role in CPS since it conveys information from the sensor(s) to the controller(s), similarly to the nerve system of human body. When facing negative environments, source and channel coding schemes can improve the efficiency and reliability of the communication system. Traditional coding schemes are designed for pure data communications and are inefficient for controlling the physical dynamics in cyber physical systems. This project studies how to integrate the awareness of physical dynamics status into the source and channel coding procedures, which improves the performance of the operation of physical dynamics. This context awareness brings a paradigm shift to the design and analysis of cyber physical systems and benefits many future systems such as smart grids. The project is extended to education purposes, including K-12 outreach, and undergraduate/graduate level course designs. The achievements of the proposed research are disseminated to academia and industry communities. This project analyzes and develops new coding schemes in the physical layer of communication for CPS, which imposes significantly different design requirements than that of the traditional networks. In particular, the project designs the coding schemes with the awareness of the physical dynamics characteristics, instead of separated designs of communications and controls. The first task is to designs new joint/iterative channel decoding and state estimation schemes that are aware of the inherent temporal/spatial redundancies in the physical dynamics observations. It begins from simple block codes and extends the work to complicated codes with cycles. Distributed source coding at the sensors is designed, which also takes the spatial and temporal redundancies into account. In particular, the criteria of source coding (e.g., the distortion) are made aware of the objectives of controlling the physical dynamics. The proposed source and channel coding schemes are evaluated in the context of smart grid monitoring and control. Both co-simulation software and hardware testbeds are implemented for the performance evaluation.