Referring to digital cellular radio systems and standards that fit under the umbrella of International Mobile Telecommunications-2000 (IMT-2000), an ITU initiative for a twentyfirst century wireless network architecture. Specifications include 128/144 kbps for high-mobility applications, 384 kbps for pedestrian speed (i.e., walking speed) applications, and 2.048 Mbps for both fixed WLL (Wireless Local Loop) and in-building applications such as WLANs (Wireless LANs). 3G systems include Universal Mobile Telecommunications System (UMTS), also known as Wideband CDMA (W-CDMA), Code Division Multiple Access 2000 (CDMA2000), and Time Division-Synchronous Code Division Multiple Access (TD-SCDMA). See also CDMA2000, cellular radio, IMT-2000, ITU-T, TDSCDMA, UMTS, W-CDMA, WLAN, and WLL.