User Guide: PTP 600 Series
Wireless operation
phn-0896_009v003
Feb 2010
UNDER DEVELOPMENT
1-19
Wireless operation
Time division duplex
PTP 600 series links use a duplexing scheme known as Time Division Duplex (TDD).
TDD operates by only allowing one end of the link to transmit at any one time. This
allows both link directions to operate on the same radio frequency, although this is not
mandatory. This differs from Frequency Division Duplex (FDD), where each end can
transmit and receive simultaneously but this does require the two directions to operate
on different frequencies, thereby increasing the demand for spectrum. TDD operates
cyclically, with the transmissions alternating between the two ends. The cycle of
events is illustrated in
, with the sequence being described as follows:
1.
Master transmits a burst to the Slave.
2.
A delay occurs as the Master burst propagates over the air.
3.
Slave receives the burst from the Master.
4.
A delay as the Slave processes the burst.
5.
The slave transmits a burst to the Master.
6.
A delay as the slave burst propagates over the air.
7.
Master receives the burst from the Slave.
8.
A delay as the Master processes the burst.
9.
Master transmits the next burst to the Slave.
A transmission from either end is called a burst. The length of the burst is called the
Burst Duration. One cycle is called a TDD Frame. The cycle period is called the Frame
Duration. To make the illustration more clear, the duration of the processing delays
and propagation delays have been exaggerated compared to the Burst Durations.
Содержание PTP 25600
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