Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
That depends. Usually both are done together. eg, when you want to do frequency division multiplexing, you just up-convert different message signals into different frequency bands. In code division multiplexing, the multiplexing is done before the modulation.