AT&T is set to become the first U.S. carrier to fully deploy HSPA (High-Speed Packet Access) technology over its network when it completes its 3G network rollout by the end of June.

HSPA is marketed by many Telcos as “mobile broadband” and actually consists of two network protocols for downstream and upstream traffic. High Speed Downlink Packet Access (HSDPA) is the part used for downloading and generally maxes up at 7.2Mbps, with 14.4Mbps being the next step up at the moment. High Speed Uplink Packet Acess (HSUPA) is meant for uploading files and tops out at 1.9Mbps.

Excerpt from Network World:

AT&T’s HSPA network currently delivers data download speeds of up to 1.4Mbps and upload speeds of up to 800Kbps. Currently, AT&T’s HSPA services are available in around 275 markets in the United States, and the company says they will be available in 350 U.S. markets by year-end.

AT&T has invested nearly $20 billion to upgrade its network to transit over to 3G services, which will be offered to all customers with a 3G handset or HSPA-enabled data modem.

I have personally been using HSPA in Singapore for more than a year now, with the last six months on an unlimited 7.2 Mbps (download) and 1.9 Mbps (upload) plan via a dedicated USB data modem. While there is a definite difference between using HSPA versus GPRS, I would advise against reading too much into the numbers.

After averaging out variances in signal strength in different locations, I would personally gauge speeds to that of a 1Mbps fixed-line broadband — even in the earlier days where there are still few users. Are you using HSPA, aka mobile broadband, on a regular basis? What are your experiences with it so far?