Most wireless carriers’ commercials feature claims that their networks are now 4G, the successor to current 3G networks. One thing these commercials fail to do is explain what 4G really is, and that’s likely because none of the major carriers — AT&T, Sprint, Verizon and T-Mobile — actually has 4G networks.

4G isn’t a technology — it’s a benchmark. According to the International Telecommunication Union (ITU), the United Nations agency tasked with regulating such things, 4G is a wireless standard. Technologies that achieve this standard can deliver peak download speeds of 100 Mbps — at least that’s what it used to mean. While wireless carriers are eager to market their latest devices as 4G, none actually deliver 100 Mbps. So instead, the carriers essentially have redefined the term “4G” to mean whatever they want it to. And the ITU has somewhat gone along with it, stating in December 2010 that “technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third-generation (3G) systems now deployed” can be called 4G. (A 3G system’s minimum download speeds typically are between 128 and 384 kilobits per second.)

Part of the reason for all the sneakiness is that technologies that will deliver true 4G speeds are still evolving, and a standard is yet to be agreed upon. U.S. carriers, for example, use different technologies to offer their 4G services. Sprint, the first major carrier to roll out 4G, uses mobile WiMAX, which can deliver download speeds at a theoretical 128 Mbps. That may seem to qualify for 4G, but real-world results are far from 128 Mbps. In fact, Sprint’s website notes that average 4G speeds are 3-6 Mbps. Verizon’s 4G is delivered via long term evolution (LTE), which is really just an upgraded version of its existing 3G network. It has a theoretical maximum of 100 Mbps, but Verizon advertises 5-12 Mbps as the average. LTE, as its name suggests, is part of an evolution. It’s the stepping stone between 3G and true 4G in the form of something called LTE Advanced. A network meeting LTE Advanced standards ultimately can achieve speeds up to 1 Gbps. Many public safety agencies are eyeing LTE Advanced as the standard for mobile broadband, once networks have been upgraded to support it.

Meanwhile, T-Mobile and AT&T also advertise that they have 4G, which comes courtesy of evolved high-speed packet access, or HSPA+ (the successor to HSPA). Like the other carriers, AT&T and T-Mobile don’t deliver that 100 Mbps. Rather, AT&T advertises a 6 Mbps average and T-Mobile says only that users may experience “theoretical peak download speeds of up to 21 Mbps.” Both companies upgraded their existing HSPA network to HSPA+ to make them faster, and then slapped on the 4G branding. Like LTE, HSPA+ is more of a transition toward LTE Advanced than actual 4G. Sprint, as mentioned, uses WiMAX for its “4G.” The next generation of WiMAX, like LTE Advanced, is expected to deliver 1 Gbps speeds. However, neither the new WiMAX (dubbed WiMAX 2) nor LTE Advanced is expected to be available commercially for another two to three years.

None of the big four wireless carriers offer real 4G; but they all have improved their existing networks and offer mobile broadband speeds that are significantly faster than 3G. Although there are some differences — HSPA was designed for voice communication while WiMAX and LTE were designed for data — the current crop of 4G offers about 10 times the speed of 3G service. While we wait for genuine 4G, there are now many choices when it comes to pseudo-4G. Sprint offers 4G in more than 50 metro areas; AT&T says most of its existing network has been upgraded to 4G; Verizon’s 4G reaches 38 metros; and T-Mobile says its 4G is in 100 metropolitan areas.

View the 4G map of coverage by the four major wireless carriers.

Chad Vander Veen  |  Editor, FutureStructure

Chad Vander Veen is the editor of FutureStructure.com