"3.5G" iPhone 4 Blazes (Where Supported)
With little fanfare, Apple has added High-Speed Uplink Packet Access (HSUPA) support to the iPhone, and it significantly improves performance. A report in ZDNet over the weekend indicated about 60% faster downloads and a 500% in upload throughput. The results will vary depending on the support for HSPA on the local AT&T cell: in Boston, I'm getting about double the download throughput I used to get with my iPhone 3G, and somewhere between eight and ten times the upload. Zowie.
The iPhone 4's support for HSUPA as well as High-Speed Downlink Packet Access (HSDPA, which was also supported by the iPhone 3GS) makes it Apple's first "3.5G" phone. AT&T is using HSPA as an evolutionary step towards its 4G LTE network which will begin deployment in 2011. The carrier has begun testing its advanced 3.5G network, capable of up to 7.2 Mbps downloads, in six cities - Charlotte, Chicago, Dallas, Houston, Los Angeles and Miami - with 19 more to come by sometime this year. HSUPA adds an additional transport channel called the Enhanced Dedicated Channel (E-DCH), which will allows for uploads as fast as 5.8 Mbps.
ZDNet did their testing out in Louisville, Kentucky which - though not a major city - has a solid network: they saw downloads in the 2 to 4 Mbps range and uploads consistently around 700 Mbps. Gizmodo tested the iPhone 4 in New York, with its notoriously congested network, and still found 5 to ten times improvement in uploads.