Introduction to Machine Learning Unit-3 for II MECH
Presnetatipn rf
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How to Analyze Crossed Feeder
Issue by DT
2. Outline
• What is crossed feeder issue
• The problems raised by crossed feeder issue
• How to detect crossed feeder issue by DT
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What is crossed feeder issue (1)
The term crossed feeder is used to describe the problem that arises when
the feeders for two or more sectors in a site are inadvertently connected
incorrectly. For Example, consider a new cell site that has three sectors,
A, B, and C:
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What is crossed feeder issue (2)
The crossed feeder problem would arise
if the feeder for sector A is connected to
sector C and vice versa. When this
happens, the sectors typically continue
to provide good coverage. However, the
network parameters for the two sectors
are also reversed. For example, the
parameters storing the sectors' BCCH
and lists of adjacent sectors would be
swapped.
For example, suppose we run a drive
test through the area served by the cell
whose feeders are crossed display the
ServBCCH attribute on the Map while
the cell sectors are colored by BCCH.
This is what we might see:
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What is crossed feeder issue (3)
There are server types of crossed feeder:
Crossed transmit feeders
Crossed receive feeders
Crossed transmit and receive feeders
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The problems raised by crossed feeder issue
Crossed Feeder SituationNormal Situation
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The problems raised by crossed feeder
issue
Crossed feeder will raise many problems, such as:
A greater degree of interference
A poor uplink signal strength
A poor performance of handover
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How to detect crossed feeder issue by DT
Crossed transmit feeders
Crossed transmit feeders will result in the swap of 2 or
more sectors BCCH frequency and TCH’s. As the sectors are
pointing in the incorrect direction, performance will suffer as
the frequency plan has been changed and a greater degree of
interference will be present.
In DT, we will find that the handset receives the single
which shouldn't have been received in the current cell.
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How to detect crossed feeder issue by DT
In the example shown above, point A is in the area of coverage of Cell D3,
but the handset at point A receives the stronger signal of Cell D2. It
indicates that TX feeders were crossed between Cell D3 and Cell D2.
Crossed transmit feeders
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How to detect crossed feeder issue by DT
Crossed receive feeders
It is not easy to detect this fault by DT, because the BCCH
frequencies will appear exactly as they were designed. However,
the statistics for the cell would help us to detect the fault:
Uplink signal strength would be very poor
Link balance would be larger than expected
Handover success rate would be very low
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How to detect crossed feeder issue by DT
Crossed receive feeders
The MR measurement is very useful in detecting this type of
feeder cross.
Uplink-and-Downlink Balance Measurement per TRX and
TCH Receive Level Measurement per TRX maybe are the
most useful statistics . For example, if the uplink-and-downlink
balance is always in level 10 or level 11, we can consider that
there is something wrong in the receive path of the site, crossed
receive feeder is a possible problem.
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How to detect crossed feeder issue by DT
Crossed transmit and receive feeder
The symptom is similar with the fault “crossed transmit
feeder”, and we can detect the fault by DT easily .
