How to Analyze Crossed Feeder Issue by DT
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Transcript of How to Analyze Crossed Feeder Issue by DT
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7/30/2019 How to Analyze Crossed Feeder Issue by DT
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HUAWEI TECHNOLOGIES CO., LTD.
www.huawei.com
Huawei Confidential
Security Level:2013/5/9
How to Analyze Crossed Feeder
Issue 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. Huawei Confidential Page 3
What is crossed feeder issue (1)
The term crossed feeder is used to describe the problem that ar ises when
the feeders for two or more sectors in a site are inadvertently connected
incorrectly. For Example, consider a new cel l si te that has three sectors,
A, B, and C:
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 4
What is crossed feeder issue (2)
The crossed feeder problem would ari se
if the feeder for sector A is connectedto sector C and vice versa. When this
happens, the sectors typical ly continue
to provide good coverage. However, the
network parameters for the two sectors
are also reversed. For example, the
parameters stor ing the sectors' BCCH
and l ists of adj acent sectors woul d be
swapped.
For example, suppose we run a dri ve
test through the area served by the cel l
whose feeders are crossed display the
ServBCCH attribute on the Map whil e
the cel l sectors are colored by BCCH .
Th is is what we might see:
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 5
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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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 6
The problems raised by crossed feeder issue
Crossed Feeder SituationNormal Situation
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 7
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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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 8
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 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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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 9
How to detect crossed feeder issue by DT
CellA CellB
Tx
Tx
Tx
Tx
Div Div
DivDiv
CellA CellB
Crossed transmit feeders
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 10
How to detect crossed feeder issue by DT
CellA CellB
Crossed transmit feeders
BCCH BCell ID B
Ms power control low (0-8)
with good RXlev
After HO low RxLev
Unexpected HOs
BCCH A
Cell ID A
Ms power control low (0-8)
with good Rxlev
After HO low RxLev
Unexpected HOs
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 11
How to detect crossed feeder issue by DT
I n 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. I t
indicates that TX feeders were crossed between Cell D3 and Cell D2.
Crossed transmit feeders
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 12
How to detect crossed feeder issue by DT
Crossed transmit feeders
Cell border Cell border
Site 3Site 2
Site 1
AA
A
BB
B
Exercise
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 13
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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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 14
How to detect crossed feeder issue by DTCrossed receive feeders
CellA CellB
Tx
Tx
Tx
Tx
Div Div
DivDiv
CellA CellB
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 15
How to detect crossed feeder issue by DT
CellA CellB
BCCH ACell ID A
Ms power control low (0-8)
with good RXlev
After HO low RxLev
Unexpected HOs
BCCH B
Cell ID B
Ms power control low (0-8)
with good Rxlev
After HO low RxLev
Unexpected HOs
Crossed receive feeders
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 16
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 thatthere is something wrong in the receive path of the site, crossed
receive feeder is a possible problem.
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 17
How to detect crossed feeder issue by DT
Crossed receive feeders
Cell border Cell border
Site 3Site 2
Site 1
AA
A
BB
B
Exercise
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 18
How to detect crossed feeder issue by DT
Crossed transmit and receive feeder
The symptom is similar with the fault crossed transmit and
receive feeder, and sometimes we can detect the fault by DTeasily .
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 19
How to detect crossed feeder issue by DTCrossed feeders both two transmit &
two receive
CellA CellB
Tx
Tx
Tx
Tx
Div Div
DivDiv
CellA
CellB
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 20
How to detect crossed feeder issue by DT
CellA CellB
BCCH B
Cell ID B
BCCH A
Cell ID A
Crossed receive feeders
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How to detect crossed feeder issue by DT
Crossed transmit - receive feeders
Cell border Cell border
Site 3Site 2
Site 1
AA
A
BB
B
Exercise
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 22
How to detect crossed feeder issue by DTone transmit & one receive feeders
crossed
CellA CellB
Tx
Tx
Tx
Tx
Div Div
DivDiv
CellA CellB
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How to detect crossed feeder issue by DT
CellA
RxLevA ~ RxLevB
BCCH A, BCCH A
Cell ID B, Cell ID B
Ms power control low (0-8)
with good RXlev
After HO low RxLev
Unexpected HOs
Crossed receive feeders
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 24
How to detect crossed feeder issue by DT
Crossed transmit - receive feeders
Cell border Cell border
Site 3Site 2
Site 1
AA
A
BB
B
Exercise
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 25
How to detect crossed feeder issue by DTInter system antenna swap (GSM CDMA)
CDMA
GSM
In this scenario when feeders has been
swapped between antenna ports, its very
difficulty to recognize it during DT. Only
abnormal coverage area and bad
performance could be the reason for this.
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 26
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 28
Receive
MulticouplerDual Duplex
UnitTRX RF Units
Du
plexerLNA
DuplexerLNAsplitter
splitter
TX
RX maindiv
TX
RX maindiv
Example:2 TRX/cell
Antennas
TX/RX-divant
XX
X
TX/RX ant
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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 29
Example:4 TRX/cell
Dual Duplex
Unit
AntennasTRX RF Units
TX
RX maindiv
DuplexerLNA
Duplexe
rLNA
splitter
splitter
splitter
splitter
TX
RX main
div
TX
RX maindiv
TX
RX maindiv
WBC
WBC
Receive Mul ticouplers
& Wideband Combiners
TX/RX ant
TX/RX-divant
XX
X
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Thank youwww.huawei.com