Thursday 26 February 2015

19:32 - 1 comment

How LTE UE determines whether LTE Network supports TDD\FDD LTE configuration?

Typically the LTE UE will either support FDD or TDD mode only. The possition, where PSS & SSS signals are transmitted, is different for FDD and TDD mode. During cell search the LTE UE has to locate & receive these signals. This is how the LTE UE knows whether the LTE cell is TDD or FDD cell.

After detection of location of SSS with respect to PSS, UE distinguish about FDD and TDD..
In FDD mode, the PSS is transmitted in the last symbol of slots 0 and 10, while the SSS is sent one symbol earlier.
In TDD mode, the PSS is transmitted in the third symbol of slots 2 and 12, while the SSS is sent three symbols earlier. thus if SSS and PSS are adjacent to each other then it is FDD and if there is two more more symbols between SSS and PSS then it is TDD 

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