Evolution of UMTS toward high-speed downlink packet access

An expanded effort is under way to support the evolution of the Universal Mobile Telecommunications System (UMTS) standard to meet the rapidly developing needs associated with wireless data applications. A new, shared channel — the high-speed downlink shared channel (HS-DSCH) — provides support to packet-switched high-speed data users. A number of performance-enhancing technologies are included in the high-speed downlink packet access (HSDPA) system to ensure high peak and average packet data rates while supporting circuit-switched voice and packet data on the same carrier. Lucent Technologies took a pivotal role in specifying many of these techniques, including adaptive modulation and coding (AMC), hybrid automatic repeat request (HARQ), and fat-pipe scheduling. In this paper, we provide system-level simulations results to indicate the achievable performance and capacity with these advanced technologies. We also discuss HSDPA protocol architecture along with the uplink and downlink control channel design and performance. We conclude with a discussion of potential enhancements for the future.