W IRELESS technologies are nowadays in widespread use, with cellular telephony and wireless Internet access being two of the major driving forces behind this. Using wireless technologies in industrial and factory automation is also very attractive for many reasons. The wireless way of communicating makes plant setup and modification easier, cheaper and more flexible. It provides a natural approach towards communication with mobile equipment where wires are in constant danger of breaking. It

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... les new applications where wireless transmission is the only option, e.g., measurements and control of rotating or highly mobile devices, and provides a novel approach to existing applications, e.g., localization and tracking of goods. Furthermore, tasks like machine diagnosis and maintenance can be greatly simplified by equipping the maintenance personnel with wireless terminals. In many factory and automation applications the communication needs are traditionally served by wired fieldbus systems and other industrial communication systems like, for example, sensor/actuator buses [1], [2] . These communication systems have been specifically designed to meet the stringent realtime and reliability requirements found in many industrial applications. Of course, wireless technologies should ideally provide the same type and quality of services to industrial users as the traditional, wired technologies do. However, wireless technologies differ in a number of ways from wired ones. These differences pose significant challenges for the design of network architectures, protocols and tools for industrial and automation applications [3], [4], [5] .