Throughput of high speed downlink packet access for UMTS

The UMTS radio interface, as defined for Release '99, provides good support for symmetrical real-time circuit switched connections (e.g. telephony). However, some applications will generate highly asymmetric data flow. As an example, downloading Web pages with significant multimedia content is likely to require high data rates, mainly in the downlink direction, but with less demanding end-to-end delay requirements than for telephony. UMTS already includes a DSCH (downlink shared channel) for such purposes. However, it has become apparent that significant further improvements in performance are possible. To this end a number of companies are working on this problem in 3GPP (3rd Generation Partnership Project) under the study item HSDPA (high speed downlink packet access). The aim is the inclusion of new performance enhancing features in a future release of the UMTS specifications.