How 4G is like 1G

In one crucial respect, fourth-generation mobile networks using Long Term Evolution represent a return to the global situation for first-generation mobile networks. Though global mobile networks were never completely identical, since multiple frequencies always have been used, LTE is the first generation of networks since the first to offer better prospects for global roaming.


In the second and third generations of technology, there were clear "islands" based on distinct air interfaces. LTE will unify the air interface to a greater extent than has been possible for some time, for example. Time division and frequency division interfaces still will exist, as well as a number of different global frequency bands. 


The main groups of frequencies will include:



700 MHz (US Digital Dividend, various bands) 170 devices
800 MHz (EU Digital Dividend, Band 20) 72 devices
1800 MHz (Band 3) 75 devices
2600 MHz (Band 7) 94 devices
800/1800/2600 MHz 57 devices
AWS (Band 4) 72 devices


But there are "backwards compatibility issues" of some magnitude, though. Some 217 existing  LTE devices also must operate on either HSPA, HSPA or 42 Mbps DC-HSPA networks. Also, 91 LTE devices support 42 Mbps HSPA technology, the Global Mobile Suppliers Association says. 



Some 108 LTE devices support EV-DO networks, as well.