devices to connect directly to a host. Because there are no wires or ports, there is no longer a need for hubs. However, to facilitate migration from wired to wireless, WUSB introduced a new Device Wire Adapter (DWA) class. Sometimes referred to as a "WUSB hub", a DWA allows existing USB 2.0 devices to be used wirelessly with a WUSB host. WUSB host capability can be added to existing PCs through the use of a Host Wire Adapter (HWA). The HWA is a USB 2.0 device that attaches externally to a desktop or laptop's USB port or internally to a laptop's MiniCard interface. WUSB also supports dual-role devices (DRDs), which in addition to being a WUSB device, can function as a host with limited capabilities. For example, a digital camera could act as a device when connected to a computer and as a host when transferring pictures directly to a printer. Connectivity W-USB can form true USB systems, formed by a host, devices and interconnection support. It implements the USB hub-spoke model, in which up to 127 wireless devices can form point-to-point links (spokes) with the host (the hub). The host controller is unique in the system and is usually embedded in a working computer, though it could be connected to it through a simple USB connection, possibly wireless as well. Such a topology is similar to a star network (but all communications are strictly point-to-point, never between devices). In order to allow common wired USB devices to be connected, the specification defines device wire adapters. Likewise, hosts connect to W-USB systems through use of a host wire adapter. Even though the physical layer is based on Ultra-WideBand, W-USB devices have a fully compliant USB interface. The physical layer may support a wide range of transfer rates, of which three are defined as mandatorily supported: 53.3, 106.7 and 200 Mbit/s, all other possible UWB rates being optional for devices (hosts must support them all). W-USB devices are categorized in the same way as traditional USB. Because of the existence of wire adapters, traditional USB hubs are not needed. A device supports one or more communication pipes to the host, and allocates endpoint 0 for the USB control pipe. Device type information is available through this pipe. Connections with the host are created by means of an establishment message sent at some point. Both host and device can then proceed to