High-Speed Downlink Packet Access
An upgrade for WCDMA / UMTS networks. It doubles network capacity and increases download data speeds five-fold or more.
Initial deployments and devices were limited to a speed of 1.8 Mbit/s. Subsequent network upgrades and new end-user devices boosted the rate to 3.6 Mbit/s, followed by 7.2, 10.1, 14.4, and 21 Mbit/s.
A related technology called HSUPA provides a similar speed boost for data in the uplink (upload) direction. Together, HSDPA and HSUPA are somtimes referred to as HSPA.
HSDPA is standardized by the 3GPP in UMTS Release 5.
In terms of data speed and general technology evolution, the closest equivalent to HSDPA for CDMA networks would be EVDO.