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 volume of IP-based traffic has already exceeded that for circuitswitched traffi c in most fixed networks. The same change will happen in mobile networks as new IP-based mobile services become available and are used by more people in their daily communications.
Current estimates show that, in advanced mobile communication markets, packet-switched traffi c will overtake circuit-switched traffic in the near future. Delivery of digital content over mobile networks as well as IP-based person-to-person communication that combines
different media and services into a single session, will generate additional traffi c and revenue. The growth in data bits used in communications will exceed the growth in revenue, driving
operators to optimize their networks to support the dominant traffic type.

HSDPA, High Speed Downlink Packet Access, offers breakthrough data speeds – up to five times (10 Mbps) higher than is possible in the most advanced 3G networks – as well as
two-fold base station capacity. For end-users this means shorter service response times and less delay.

Meanwhile, operators will be able to offer advanced services at lower costs and with increased profitability. As the Nokia HSDPA solution is fully backwards compatible with current
Nokia WCDMA networks, it is a costeffective way to upgrade existing infrastructure. By providing higher quality and capacity it will help to drive up the consumption of dataintensive
services, bringing operators more revenue. HSDPA offers by far the highest performance at the lowest cost, enabling real mass-market mobile IP multimedia. HSDPA is based on WCDMA evolution, standardized as part of 3GPP Release 5 WCDMA specifi cations. The new
modulation method of HSDPA greatly improves the peak data rate and throughput, which enhances spectral effi ciency. In addition to these benefits, users will perceive faster connections
to services through shorter round trip times.

As a result of these enhancements, operators using HSDPA will be able to support considerably higher numbers of high data rate users on a single radio carrier than is possible with any
existing 3G technology.

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.