authenticate using their unique keys; if the process succeeds, the host assigns a unique USB address to the device, after which the device becomes visible to the USB protocol. Because the connectivity model allows for on-the-fly, unannounced disconnection, connections must always remain active. Aside from host- or device-forced disconnections, long inactivity periods may trigger the same termination mechanisms. In addition, W-USB hosts have other responsibilities which go beyond those of a wired host; namely, their MAC sublayer is responsible for supervising the suitability of device MAC layers. If needed, this requires assisting them in their beaconing duties and processing the beaconing data that could be sent to them. Furthermore, the UWB radio and associated bandwidth may be shared with other entities, and the host must make sure that the defined policies are satisfied; according to shared use (which may be coordinated to avoid interference) it will be able to offer full or partial functionality. Relation to ultra-wideband UWB is a general term for radio communication using pulses of energy which spread emitted Radio Frequency energy over 500 MHz+ of spectrum or exceeding 20% fractional bandwidth within the frequency range of 3.1 GHz to 10.6 GHz as defined by the FCC ruling issued for UWB in February 2002. UWB is not specific to WiMedia or any other company or group and there are in fact a number of groups and companies developing UWB technology totally unrelated to WiMedia. WUSB was a protocol promulgated by the USB Implementers Forum that used WiMedia's UWB radio platform. Other protocols that announced their intention to use WiMedia's UWB radio platform included Bluetooth and the WiMedia Logical Link Control Protocol. Wireless USB vs. 60 GHz A few issues differentiate Wireless USB from other proposed/competing standards that utilize 60 GHz band like WiGig: Line of sight At 60 GHz, radio communication is blocked by any intervening object, which implies the need for open line of sight. Wireless USB was based on the Ultra-WideBand (UWB) platform, which operates in the 3.1 to 10.6 GHz frequency range, and thus can pass through intervening bodies. Mobility The 60 GHz technology was appealing to the wireless video market because it was supposed to deliver multi-gigabit-speed wireless communications. In order to support such heavy demands, the underlying MAC layer should have been able to process this huge amount of data. For these requirements, the 60 GHz-based products needed higher power consumption, and