HSDPA (High-Speed Packet Downlink Access, also known as 3.5G) offers the possibility for a significant extension of UMTS capabilities. The acceleration in transmission provided by HSDPA is urgently needed to meet customer demand for high-speed data services. In addition, HSDPA has the potential to make the network more efficient and therefore decrease operational costs.

Current WCDMA (Release 99) systems fulfill the general requirements of voice and data services well, by providing data transmission rates up to 2 Mbps, supporting high-speed packet switching/circuit switching and a many internet-based services.

Nevertheless, the rapid expansion of bandwidth-consuming services, e.g. streaming media and file-sharing, bring the need for higher bit rates and lower delay to mobile systems. Therefore, in Release 5 specifications 3GPP focuses on a new packet-based data service: High Speed Downlink Packet Access (HSDPA), which is also treated as a 3.5G technology.

HSDPA Main Objective

The main objective of HSDPA is to increase maximum user throughput for downlink packet data and to reduce packet delay. At the same time the system keeps enough compatibility, all techniques in Release 99 can also be supported in a network supporting HSDPA, and UE with HSDPA capability can co-exist with R99 UE on the same carrier. Thus, in Release 5, after the introduction of HSDPA, UTRAN functional hierarchy is still valid, and it has no impact on RLC, only adding some new parameters in RRC. The most remarkable change occurs on the MAC sublayer; a new MAC-hs entity is added in Node B with several new techniques and functions.

HSDPA Related Products