Cellular towers communicate in two ways. One is through a set of channels assigned to handle telephone calls. The other is through a separate set of channels that provide wireless Internet access. It wasn't that many years ago that data was an afterthought for cell phones. Texting was the primary application, with email rising in popularity. Dial-up speeds were plenty good enough to handle slow text based services. But then cell phones started including cameras. With cameras came the demand to be able to send those pictures to other phones and post them on Internet sites. Web browsers started to be included. Today, the best ones are full HTML capable and work the way you'd expect on a desktop or notebook computer. The final straw is video. People aren't satisfied waiting for short low definition video clips to download. Now they want high quality streaming video and even live TV.
As you can imagine, these faster applications have increased the demands on cellular service the same way they did for home and business access. Dial-up is totally inadequate. Entry level broadband is noticeably poky. What everyone wants is the same speeds they get at home and at work. That's typically in the 3 to 10 Mbps range for what's considered "fast" service today.
The first Apple iPhone operated on what is called the EDGE network. That's an acronym for Enhanced Data Rate for GSM Evolution. It refers to a protocol used by GSM carriers, a popular International standard. AT&T is a GSM carrier. AT&T advertises EDGE download speeds as being in the range of 75 to 135 Kbps on the average. Peak speeds are higher, but it depends on how close to the tower you are and how many other users are sharing the service. Enhanced means enhanced over the previous dial-up speeds offered on the network.
The second version of the iPhone runs on the AT&T 3G Network which uses a different protocol called HSPA or High Speed Packet Access. Download speeds are improved to 700 Kbps to 1.7 Mbps, with fast upload speeds of 500 Kbps to 1.2 Mbps. Peak speeds can hit 3.6 Mbps. That's a lot faster, and more typical of what you need to run today's demanding applications even in a mobile environment.
But there's no way that AT&T can afford to rest at this plateau of performance. In fact, they're reportedly doubling their HSPA technology with software upgrades to achieve a peak bandwidth of 7.2 Mbps. That probably equates to 1 to 2.4 Mbps on average for typical use. There is also another upgrade possible to double that to a peak capacity of 14.4 Mbps.
The days of 3G are numbered, however. The hot new technologies are LTE (Long Term Evolution) and WiMAX which promise bandwidths of 10 Mbps or more. Sprint and Clearwire are building out WiMAX. Verizon and AT&T are going with LTE. This technology will have the designation of "4G" to imply another generation of wireless technology. Until the economy picks up, though, don't expect a rapid deployment of 4G this year or even next. After that, 4G could become the new 3G and everybody will wondering when they're going to get something really fast... like 5G.
