Why do I need two SWs in a front-end module?

I'm developing a front end module , including PA,LNA,SWx2,IPD.
I got a question about that , why is there 2 SW ?

TKS

One for Tx/Rx selection : TDD ( Time Division Duplex ) mode

One for antenna diversity

You normally find in digital system e.g Dect

it will depend on ur design

also i have seen ppl use 2 swt or a triplexer , for multiband operation like a phone and GPS ,

khouly