Time Division Duplex (Tdd) Synchronization; Introduction; Figure 34 - Co-Location Of Links Interference Problem - A Simple Example - Motorola PTP 600 Series User Manual

5.12 Time Division Duplex (TDD) Synchronization

5.12.1 Introduction

In a TDD system, a radio transmits for a portion of the radio frame and receives in a different
portion of the frame. Motorola PTP600 links consist of a Master unit and a Slave unit with the
Master transmitting for the first part of the radio frame (Slave receiving) and the Slave
transmitting in the remainder of the radio frame (Master receiving). The portion of the frame
apportioned to each period can be dynamic, for example in IP optimisation mode where the
split is a function of the offered traffic in each direction. However, if the frames of the two links
are not aligned in time, then an interference mechanism exists where one Master unit may be
transmitting when the Master unit from the other link is receiving. A similar mechanism exists
for Slave units. The level of interference becomes very signicant when the units are located in
close proximity, for example when units are located on the same mast. This problem is
illustrated in Figure 34 where it can be seen that transmissions from Master unit A overlap
with the receive portion of Master unit B and vice versa.

Figure 34 - Co-location of Links Interference Problem - A Simple Example

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