e host. reservations made by the host and by non-cluster devices are mutually observable and respected. Directed beaconing devices must support three functions to enable these capabilities; A Count Packets function; by periodically counting packets during the beacon period, the host can determine whether a directed beaconing device has any hidden neighbours. A Capture Packets function; by capturing the beacon transmission of a hidden neighbour, the host can determine its DRP reservations, and adjust its own reservations if necessary. A Transmit Packet function; by providing the appropriate beacon data and instructing a directed beaconing device on when to transmit it, the host can inform the hidden neighbour of the presence and DRP reservations of nearby devices in the cluster. These control mechanisms also ensure that several wireless USB clusters can spatially overlap with minimum interference. The wireless USB protocol defines the packet formats and controls the various types of data transfers (bulk, isochronous and control) within the micro-scheduled wireless USB channel. The protocol also provides control of a range of measures designed to mitigate the effect or RF interference on transfer reliability, including control of transmit power, bit rate and size of the data payload within a transmitted packet, as well as bandwidth and RF channel switching. Chapter Ten Wireless USB in Practice One of the design goals of wireless USB is that it should preserve the "plug and play" ease of use associated with wired USB. The equivalent wireless concept of "turn on and use" will require wireless USB devices to automatically install drivers and security features when turned on for the first time, as well as identifying and associating with other devices with a minimum of user input for authentication. Besides the hub and spokes topology that allows a host to control up to 127 end-point devices, wireless USB allows a dual role device (DRD) to function as both a host and a device simultaneously. This allows simple peer-to-