High-Speed Downlink Packet Access (HSDPA) (Sometimes known as High-Speed Downlink Protocol Access) is a 3G mobile telephony protocol in the HSPA family, which provides a roadmap for UMTS-based networks to increase their data transfer speeds and capacity. Current HSDPA deployments now support 1.8 Mbit/s, 3.6 Mbit/s, 7.2 Mbit/s and 14.4 Mbit/s in downlink.

Further speed grades are planned for the near future. The networks are then to be upgraded to HSPA Evolved, which provides speeds of 42 Mbit downlink in its first release.[1]

In addition to supporting high data speeds, HSDPA greatly increases the capacity of the network. Current HSDPA networks have the capacity to provide each customer with 30 gigabytes of data per month in addition to 1000 minutes of voice and 300 minutes of mobile TV

3GPP - Third Generation Partnership Project
BTS - Base Station
DCH - Dedicated Channel (transport channel)
HS-DSCH High Speed Downlink Shared Channel
HSDPA High Speed Downlink Packet Access
HW Hardware
IP Internet Protocol
MS Mobile Station
PS Packet Switched
QoS Quality of Service
RAN Radio Access Network
RNC Radio Network Controller
SW Software
WCDMA Wideband Code Division Multiple Access

The WCDMA air interface has been standardized by the 3rd Generation Partnership Project (3GPP) as a radio transport medium for global mobile communication systems. Consequently, the fi rst versions of the 3GPP air interface specifications enabled superior user data rates and
system throughput capacities compared to any 2nd generation mobile communication standard.

The WCDMA system’s adaptability enables a new and significant evolutionary step in packet data
access: the HSDPA Solution. HSDPA is standardized in 3GPP
Release 5.