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

近年来，人们对网络物理系统进行了大量的研究。一个典型的网络物理系统由物理部分和网络部分组成。物理部分是指遵循物理规律的动力学，而网络部分(由传感器(S)、通信和控制器(S)组成)观察物理动力学，传输报告，并做出控制动作。许多实际应用可以被认为是网络物理系统，如智能电网、无人驾驶飞行器和机器人网络。通信部分在CPS中起着关键作用，因为它将信息从传感器(S)传递到控制器(S)，类似于人体的神经系统。当面临负面环境时，信源和信道编码方案可以提高通信系统的效率和可靠性。传统的编码方案是为纯数据通信而设计的，并且对于控制网络物理系统中的物理动力学是低效的。本项目研究如何将物理动力学状态的感知融入到信源和信道编码过程中，从而提高物理动力学运算的性能。这种背景感知为网络物理系统的设计和分析带来了范式转换，并使许多未来系统(如智能电网)受益。该项目扩展到教育目的，包括K-12外展和本科生/研究生水平的课程设计。本课题分析并开发了CPS通信物理层的新编码方案，这与传统网络的设计要求有很大的不同。特别是，该项目在设计编码方案时意识到了物理动力学特性，而不是分开设计通信和控制。第一个任务是设计新的联合/迭代信道译码和状态估计方案，该方案能够意识到物理动力学观测中固有的时间/空间冗余。它从简单的分组码开始，并将工作扩展到具有循环的复杂代码。在传感器端设计了分布式信源编码，同时考虑了空间和时间上的冗余。具体地，使信源编码的标准(例如，失真)意识到控制物理动力学的目标。在智能电网监控的背景下，对所提出的信源和信道编码方案进行了评估。实现了协同仿真软件和硬件试验台，用于性能评估。

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.