The followings are general conclusions for applying UPBO in real network.
•Non-FEXT dominated environment: Do not apply UPBO!
It only causes SNR reduction in short loops with no SNR improvement in long loops.
•FEXT-dominated environment:
Apply UPBO for all loops shorter than the longest one!
It always could be found an appropriate UPBO value avoiding any SNR reduction and even improving the SNR in either long or short loops (because of lower FEXT coupling in short loops).
Modes of UPBO
Defines the goal of the UPBO for the particular deployment. This goal usually allows avoiding performance degradation in some loops at expenses of another loops.
The appropriate mode for particular deployment is supposed to be set by the network operator. Standards should specify the recommended modes.
1. Protection of the long loop
Performance of the selected service over the selected Long loop is kept with no degradation (or with a controlled small degradation) relatively to the “equal length” scenario on the expense of shorter loops. Performance degradation for loops either shorter or longer that the Long loop are NOT restricted.
POZ: Doesn’t require any knowledge on the noise environment. The implementation is straightforward.
NEG: Protects actually only one loop (one dedicated service)
2. Equal maximum degradation for all loops
Loop of any length may be degraded relatively to the “equal length”scenario. The maximum value of degradation (usually expressed in SNR margin) is equal for all loops.
POZ: Penalizes all services equally (theoretically, by 3 dB of SNR margin).
NEG: Requires exact knowledge of the noise environment. The UPBO needs to be updated for any change in FEXT and
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