LTE devices operate in either of two modes: TDD (time domain duplex) or FDD (frequency domain duplex). In FDD transmission and reception takes place at different frequencies whereas in TDD transmission and reception takes place at the same frequency but different time slots. The are separate frequency allocations for these two modes but some bands are common between the two modes. Given below are the frequency allocations for FDD.
There is suitable separation between the uplink and downlink frequency bands (at least 10MHz) so that the transmitted signal does not feedback into the receiver. It is extremely difficult to build a device that works in all of these 22 bands (due to limitations of practical antennas). Practical devices would at most be quad-band or penta-band. So an LTE device that would work in all parts of the world is more of a dream!
Author: John (YA)
John has over 15 years of Research and Development experience in the field of Wireless Communications. He has worked for a number of companies around the world including Qualcomm Inc. USA. He has an MS in Electrical Engineering from Virginia Tech USA and has published his work in international journals and conferences.