ZyXEL Communications IES-5005 - Manual (Page 51)

IES-5000/5005/6000 Support Notes
50
Upstream Power Back-Off (UPBO)
What is UPBO?
Upstream Power back-of (UPBO) helps to run services over loops with different length
co-located in the same cable binder (“mixed length” deployments), especially in
FEXT-dominated noise environment.
Strong FEXT generated by short loops can significantly degrade the performance of long loops
if UPBO is not applied. On the other hand, UPBO reduces the transmit power of short loops
and thus degrades their performance as well.
PSD
PSD
PSD PSD
PSD
f
f
f f f
Enable UPBO to allow the system to adjust the transmit PSD of all lines based on a reference
line length so that the PSD at the receiving end is the same.
PSD PSD
f f
PSD
f
PSD
f
PSD
f
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