What Is Time Division Duplex (TDD)?


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shahid tauqeer Profile
shahid tauqeer answered
TDD also known as time-compression multiplexing (TCM)
Data transmitted in one direction at a time, with transmission between the two directions
Simple TDD

Simple TDD
Bit stream is divided into equal segments, compressed in time to a higher transmission rate, and transmitted in bursts
Effective bits transmitted per second:
R = B/2(Tp+Tb+Tg)

R = effective data rate
B = size of block in bits
Tp = propagation delay
Tb = burst transmission time
Tg = guard time
Actual data rate, A:
A = B /Tb
Combined with previous equation:

The actual data rate is more than double the effective data rate seen by the two sides

Wireless TDD typically used with TDMA
A number of users receive forward channel signals in turn and then transmit reverse channel signals in turn, all on same carrier frequency
Advantages of TDMA/TDD:
Improved ability to cope with fast fading
Improved capacity allocation

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