Recently, mobile carrier company SK Telecom told the Korea Times that the next generation iPhone widely rumored to be named the iPhone 5S will support LTE Advanced. SK Telecom says that they approached Apple with the idea and that they are "in the middle of negotiations" as we speak.
The Korean Times says that Apple will probably use a QUALCOMM chip to support the standard instead of their own "A" series SoC. LTE Advanced is the next generation of the 4G LTE standard which could potentially double the download speeds available to the iPhone in supported areas. The technology works by spreading a single download over multiple radio channels. At the moment, only South Korea has an extensive LTE Advanced network in place.