Potential of multipath communications to improve communications reliability for internet-based cyberphysical systems

For cyber-physical systems (CPSs), communications system reliability is an indispensable requirement to realize them in critical infrastructures. One of the important attributes of system reliability is availability. System availability is broadly defined as the proportion of time that the system will provide service. In some CPSs, such as smart grids, the units are distributed over large geographical areas. For such systems, the use of Internet to connect their units is highly desirable. However, the reliability of today's Internet was considered to be inadequate to support many CPSs. In this paper, we propose the utilization of multipath (MP) communications using different end-to-end (e2e) paths to improve communications reliability of Internet for CPSs. With this regard, we first formulate the problem of multipath selection to provide the required communications reliability as an optimization problem. After that, we conduct first real world measurements to investigate the diversity of different e2e paths and the reduction in communications service unavailability when 2 and 3 paths between the source and destination are considered simultaneously. Our results indicate the existence of e2e paths that traverse completely different networks and, consequently, are likely to be disjoint. In addition, the concurrent unavailability of different 2 and 3 paths combinations was 0. The results show that MP communications using different e2e Internet paths can achieve the required reliability by many CPSs such as smart grids.