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.
- LTE 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: Yasir
More than 20 years of experience in various organizations in Pakistan, the USA, and Europe. Worked with the Mobile and Portable Radio Group (MPRG) of Virginia Tech and Qualcomm USA and was one of the first researchers to propose Space Time Block Codes for eight transmit antennas. Have publsihed a book “Recipes for Communication and Signal Processing” through Springer Nature.