An Approach to Fault-Tolerant Clock Synchronization for Wireless Local Area Networks

1 Introduction We are working on the development of a system architecture that enables autonomous mobile systems to cooperate in real-time using their own distributed infrastructure such as computing resources and wireless communication channels. Due to locomotion of the mobile systems, the cooperation is subject to strong real-time constraints. Furthermore, the systems share and compete for resources, e.g. network bandwidth. Our work aims at providing a hierarchy of real-time communication protocols that support the cooperation of autonomous intelligent systems. These protocols should support real-time and fault-tolerance properties. The development of the protocols is based on the IEEE 802.11 standard for wireless communication in local area networks [IEEE 97]. The protocols will be implemented in conformance with the infrastructure networks defined in the standard so that they can be used on standard hardware components (e.g. Lucent's WaveLan cards). The functionality of the standard is enhanced with respect to real-time and fault-tolerance properties either by adding additional protocol layers and, if necessary, by extending the standard implementation of the medium access control layer on the level of the device drivers.