When the Wall Street Journal came out with the speculation that the iPhone 5 would feature 4G LTE, this was largely a non-news as virtually everyone expects LTE to happen in the iPhone 5 as 1/users demand it 2/ wireless carriers want LTE phones, period. The more interesting bit from WSJ was that LTE would work outside of the US market, which is unusual for LTE phones: most fall back to HSPA+ in Europe and elsewhere.
This happens because unlike HSPA+ and 3G, the radio bands (frequencies) used for 4G LTE are very different from one country (or one carrier) to the next. Even in the USA, LTE is not interoperable from one carrier to the next.
This did not prevent a “global” iPhone 5 4G LTE support rumor to spread on the web like wildfire. Of course, iPhone 5 users who are heavy travelers rejoiced right away. Those who had a prospect to resell the phone globally did so as well (prices are much higher in markets where the phone is not officially available). However, here is the cold shower:
there are more than 41 LTE bands used worldwide, and there is no radio capable of supporting all (or even “most”), of them. Supporting five bands is already great. In the short term, more radios would need to be added, which seems to be unlikely.
Of course, there are “programmable radios” as well, but so far, none can handle all the bands. We’ve recently talked to Qualcomm’s CEO Dr. Paul Jacobs about this very problem, and there is clearly more work required to get anywhere close that “global support” goal.
If you listen to those rumors, you should really take “global” with a grain of salt. If global means that the iPhone 5 4G LTE may work “somewhere on each continent”, then why not. If you think that it will work in “most developed countries”, don’t hold your breath on it.
Most likely, Apple will have to either support a limited number of LTE carriers which are using the 4 or 5 same bands (bye bye “global” support), or they will have to create different versions of the phone (with a different chip/radio) according to the target bands. I think that Apple will go for the former: supporting a limited number of bands and carriers, with a HSPA+ fallback — but who knows? What do you think?