01dtanalysis Howtoanalyzecrossedfeederissuebydt Copy 120506035720 Phpapp01

8/11/2019 01dtanalysis Howtoanalyzecrossedfeederissuebydt Copy 120506035720 Phpapp01

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

Security Level:2008-11-3

How to Analyze Crossed FeederIssue by DT


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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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HUAWEI TECHNOLOGIES CO., LTD. Page 3Huawei Confidential

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 feederissue

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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Crossed transmit feeders

Crossed transmit feeders will result in the swap of 2 or

more sectors BCCH frequency and TCHs. 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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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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The MR measurement is very useful in detecting this type offeeder 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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Crossed transmit and receive feeder

The symptom is similar with the fault crossed transmit

feeder, and we can detect the fault by DT easily .


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Thank youwww.huawei.com

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01dtanalysis Howtoanalyzecrossedfeederissuebydt Copy 120506035720 Phpapp01