Network latency and packet delay variation in cyber-physical systems

The problem addressed in this paper is the limitation imposed by network elements, especially Ethernet elements, on the real-time performance of timecritical systems. Most current network elements are concerned only with data integrity, connection, and throughput with no mechanism for enforcing temporal semantics. Existing safety-critical applications and other applications in industry require varying degrees of control over system-wide temporal semantics. In addition, there are emerging commercial applications that require or will benefit from tighter enforcement of temporal semantics in network elements than is currently possible. This paper examines these applications and requirements and suggests possible approaches to imposing temporal semantics on networks. Modelbased design and simulation is used to evaluate the effects of network limitations on time-critical systems.