Duplexing

Duplexing :

Duplexing is the technique by which the send and receive paths are separated over the medium, since transmission entities (modulator, amplifiers, demodulators) are involved.

There are two types of duplexing.\

1. Frequency Division Duplexing FDD

2. Time Division Duplexing TDD 

      Frequency Division Duplexing FDD

Different Frequencies are used for send and receive paths and hence there will be a forward band and reverse band. Duplexer is needed if simultaneous transmission (send) and reception (receive) methodology is adopted .Frequency separation between forward band and reverse band is constant

Time Division Duplexing (TDD)

TDD uses different time slots for transmission and reception paths. Single radio frequency can be used in both the directions instead of two as in FDD. No duplexer is required. Only a fast switching synthesizer, RF filter path and fast antenna switch are needed. It increases the battery life of mobile phones.

GSM and CDMA systems use Frequency Division Duplexing and corDECT uses Time Division Duplexing.