e "existence" independent of their constituent devices. If all the devices migrated out of a WLAN's coverage area and replacement units arrived, the WLAN would be said to have uninter- rupted existence. This concept is not true for IEEE 802 WPANs. If the master (station) does not participate, the network no longer exists. In a WPAN a device creates a connection that lasts only for as long as needed and has a finite lifespan. For example, a file transfer application may cause a connection to be created only long enough to accomplish its goal. When the application terminates, the connection between the two devices may also be severed. The connections that a mobile client device creates in a WPAN are ad hoc and temporary in nature. The devices to which personal device is connected in a WPAN at one moment may bear no resemblance to the devices it was previously connected with, or will connect with, in the future. For example, a notebook computer may connect with a PDA at one moment, a digital camera at another moment, and a cellular phone at yet another moment. At times, the notebook computer may be connected with any or all of these other devices. The WPAN technology must be able to support fast (i.e., in a few seconds) ad hoc connectivity with no need of predeployment of any type. The IEEE 802.15.1 utilizes Bluetooth wireless technology. In this section and in IEEE 802.15, the term Bluetooth WPAN refers to a WPAN that utilizes the Bluetooth wireless technology (Ref. 6). 13.5.1.4 OSI Relationship. Figure 13.2 illustrates the relationship of the IEEE 802.15.1 standard and open systems interconnection (OSI). The figure shows the separation of the system into two parts: the PHY and the MAC sublayer of the DLL (data-link layer) SO that it corresponds to the lowest layers of ITU-T Rec. X.200. 13.5.1.5 Overview of the Bluetooth WPAN. The Bluetooth wireless technology uses a short-range radio link that has been optimized for power-conscious, battery-operated, small-size, lightweight personal devices. A Bluetooth WPAN suppo