Clock synchronization for wireless local area networks

High-precision clock synchronization is one of the most basic requirements in distributed real-time systems. This paper presents an enhanced clock synchronization protocol for wireless local area networks based on the IEEE 802.11 standard. Reducing the time-critical path of the protocol enhances the synchronization precision. As wireless communication links are inherently unreliable, special emphasis is put on fault tolerance. The protocol guarantees high precision even in the presence of message losses. The protocol is implemented in a Windows NT NDIS driver for Lucent WaveLAN cards. For this driver-level implementation, our measurements have shown that a precision of 150 /spl mu/s is achieved.