The International Telecommunications Union (ITU) and the 3rd Generation Partnership Project (3GPP) are the worldwide developers and standardization organizations for cellular technologies. The IEEE, which standardizes WiMAX (802.16), says that Long-Term Evolution (LTE) and WiMAX are really 3G and not 4G.
The ITU defines 4G as IMT-Advanced or, more specifically, LTE Advanced and WirelessMAN Advanced, which are more highly developed versions of the current LTE and WiMAX standards that will offer wireless speeds to 1 Gbit/s. For example, LTE uses 20-MHz channels but later versions will use 40-MHz or even 100-MHz channels plus multiple input/multiple output (MIMO) to achieve the targeted 1-Gbit/s speeds.
These Advanced versions won’t be ready for another few years. Nevertheless, that’s not what the cellular operators and handset manufacturers are saying. The carriers are currently spending billions building out their networks to handle LTE and WiMAX, both truly the next big wireless developments beyond 3G. And they are marketing the new handsets and services as 4G despite what the ITU says.
Even HSPA+ is being sold as a 4G technology. With data speeds of 21 to 42 Mbits/s thanks to 64-state quadrature amplitude modulation (64QAM) in the 5-MHz channels, it comes close to delivering similar performance as LTE and WiMAX. The ITU’s Advanced LTE and WiMAX versions will no doubt be labeled 5G by the carriers well into the future.