HSDPA (High Speed Downlink Packet Access) Sometimes characterized as a 3.5G cellular radio technology, HSDPA is an upgrade to Universal Mobile Telecommunications System (UMTS) that increases theoretical downlink data rates to 14.4 Mbps, although current implementations support speeds more typically in the range of 400–700 kbps, bursting up to 3.6 Mbps for short periods of time using an adaptive modulation technique to throttle bit rates up and down as the link permits. Work has begun in the 3rd Generation Partnership Project (3GPP) on standards for High Speed Uplink Packet Access (HSUPA). See also 3GPP, cellular radio, downlink, link, modulation, and UMTS. 74570c08.qxd 9/11/07 12:22 PM Page 230 |