Pim test vms1 jan, 2012 compatibility mode

PIM TEST REPORT
with VSM MOBIFONE CENTER 1

Created by Tuoi Ngo

Hanoi capital , Vietnam – Jan, 2012


CONTENT
I.
II.
III.
IV.
V.

Why need PIA – Passive Intermodulation Analyzer?
PIA product introduction
Site list for test
Summarization and Test Results
Further recommendations, considerations


Passive Intermodulation (PIM) is a nonlinear response of two or more signals of different
frequencies mixing together in a passive device, e.g. antenna, cable, connector and
splitter. In the pass, PIM was of little concern to passive device designers. But now, due
to frequency planning of the modern communication network, the usage of higher power
transmitters , and more sensitive receivers in base stations, PIM has become a very
serious and challenging problem for mobile operators, equipment vendors and
component manufactures. In a PIM with sufficient magnitude generated from a
transmitter falls within an adjacent receiver channel, it caused a serious interference to
the base station receiver and will largely degrade the network quality of service. The

problem must be overcomed in order to improve network performance for mobile
operators and maintain high quality for subscribers.

Besides macro network configurations, there
are 4 causes from the physical interface
onsite for poor KPI today, and passive
intermodulation (PIM) test are used as a key
indicator for site audit
•
Antenna, feeder system aging
over the time, performance
degradation caused by product
materials & environment
•
Low quality feeder, passive,
antenna
system
deployed
without qualification test
•
Poor
Workmanship
during
installation
without
proper
testing procedure
•
Lack
of

preventive
testing
instruments
&
troubleshooting `


II. PIA product introduction
Passive
Intermodulation Anlyzer

PIA Data Sheet


II. PIA product introduction


II. PIA product introduction


SITE INFORMATION
Site Name

Inspection Onsite Date

Site type

Ha Dinh 2

Jan 6, 2012

New site

Nguyen Trai 4

Jan 6, 2012

Co site

Jan 9, 2012

Co site

Chua Ha


IV. Summarization and Test Results
PIM TEST_ VMS1_
Jan, 2012

1.Summarization
Site Audit Record
No.

1

Site Name

Actual
Onsite

Onsite
Antenna
Date information

Ha Dinh 2

900/1800
Dual band
antenna
(Agison-PN
2127010548
10)

6-Jan

Site type

New Site

Cell

PIM test before
Audit

Cell A

Pass

2

3

Nguyen Trai
4

Chua Ha

1800 Single
band
9-Jan
antenna
(N/A PN)

Co Site

None

PIM after Audit

Passed

Cell B

Pass

None

-

Cell C

Pass

None

-

Cell A
900/1800
Dual band
6-Jan
antenna
(Kathrien -PN
1011856/1)

Problems found during
Deal with the problem
Audit

Cell B

01 Failed and 01
Low PIM result
Pass

Failed

Low PIM result

Cell C

Pass

None

Cell A

Pass

None

Co Site

Bad workmanship,
antenna is aging and
need to be considered
for replacement
Antenna is aging and
need to be considered
for replacement
The PIM result is still
passed, however it's
not really good, (
expecting the result is
less than - 110 dBm for
good performance)
The PIM result is still
passed, however it's
not really good, (
expecting the result is

less than - 110 dBm for
good performance)

Cell B

01 Failed and 01
Low PIM result
Pass

Bad workmanship ,
tightened connector

Cell C

01 Failed and 01
Low PIM result
Pass

Bad workmanship ,
tightened connector

Remark

PIM result is not
really good, less
than 110 dBm is
better PIM result

Passed
Bad workmanship,

antenna is aging,
01 Failed and 01 need to have plan
Pass
for fixing and
antenna
repalcement
Antenna is againg ,
Passed
need to have plan
for replacement

Passed

PIM result is not
really good, less
than 110 dBm is
better PIM result

Bad workmanship,
and some cells
PIM result
themselves are not
really good , ( less
than -110 dBm is
Passed
considered as
01 Failed and 01 good result)
Pass
Passed

IV. Summarization and Test Results
2. Test Results
Site name: Ha Dinh 2
Antenna information: site with 2 antenna
systems
 2G:


900/1800 Dual band antenna
(Kathrein 741322)

Antenna port

PIM threshold
value (dBm)

PIM actual test
value
(dBm@MHz)

Remark

Cell A-Dual band
antenna port A

≤ -90

Pass

Cell A-Dual band
antenna port B

≤ -90



Pass

Cell B-Dual band
antenna port A

≤ -90



Pass

Cell B-Dual band
antenna port B

≤ -90



Pass

Cell C-Dual band

antenna port A

≤ -90



Pass

Cell C-Dual band
antenna port B

≤ -90



Pass

 3G: N/A


IV. Summarization and Test Results
2. Test Results
Site name: Ha Dinh 2 – Cell A

Dual band antenna port A

TEST RESULT

Dual band antenna port B

IV. Summarization and Test Results
2. Test Results
Site name: Ha Dinh 2 – Cell B

Dual band antenna port A

TEST RESULT

Dua band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Ha Dinh 2 – Cell C

Dual band antenna port A

TEST RESULT

Dual band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Nguyen Trai 4
Antenna information: site with 2 antenna
systems
 2G:


900/1800 Dual band antenna
(Kathrein 1011856/1)

 3G: N/A

Cell A-TX1 feeder itself is shorter
than others and not fixed by
cable tight shaking up in the air
and due to antenna age which
caused to bad PIM result -33.4
dBm.

Antenna port

PIM threshold
value (dBm)

PIM actual test
value
(dBm@MHz)

Remark

Cell A-Single band
antenna port A

≤ -90

Failed

Cell A-Single band
antenna port B

≤ -90



Pass

Cell A-Single band
antenna port A

≤ -90

Cell B-Single band
antenna port B

≤ -90



Failed

Cell B-Single band
antenna port A

≤ -90

Pass

Cell C-Single band
antenna port B

≤ -90



Pass



Failed

Loose connections between
surge arresters and 7/8 inch
indoor connectors


IV. Summarization and Test Results
2. Test Results
Site name: Nguyen Trai 4 – Cell A

Dual band antenna port A

TEST RESULT

Dual band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Nguyen Trai 4 – Cell B

Dual band antenna port A

TEST RESULT

Dua band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Nguyen Trai 4 – Cell C

Dual band antenna port A

TEST RESULT

Dua band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha
Antenna information: site

with 1 antenna system

Antenna port

PIM threshold value
(dBm)

PIM actual test
value (dBm@MHz)

Remark

Cell A-Single band
antenna port A

≤ -90



Passed

Cell B-Single band
antenna port B

≤ -90



Passed

 2G:


1800 Single
band antenna:
N/A PN and
serial number.

Cell B-Single band
antenna port A

≤ -90



Cell B-Single band
antenna port B

≤ -90



Cell C-Single band
antenna port A

≤ -90



Cell C-Single band

antenna port B

≤ -90



At the beginning, PIM resulted had been not
passed with result
But after tightening connector, the
result was getting better and passed the
threshold finally

Passed

Passed

Loose
connection
indoor
with
PIM
result:
after
tightening
connector, the result was getting better however
it wasn’t still not good enough to pass threshold
-90dBm, need to check other elements in order
improving PIM result itself.

Bad workmanship -Loose

connectors tightening cause to
bad PIM result , fixed OK


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha – Cell A

Single band antenna port A

TEST RESULT

Single band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha– Cell B1

Single band antenna port A before connector tightening

TEST RESULT

Single band antenna port A after connector tightening


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha– Cell B2

TEST RESULT

Single band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha – Cell C1

TEST RESULT

Single band antenna port B


IV. Summarization and Test Results
2. Test Results
Site name: Chua Ha – Cell C1

Single band antenna port B before connector tightening

TEST RESULT

Single band antenna port B after connector tightening


V. Further recommendations, considerations
After inspecting some MobiFone sites in Hanoi capital, we have conclusions as below:
Advantages:
- Inspected sites are high configuration with almost high traffic at every hour in day.
- All BTSs with full capacity of hardware are working normal in good condition of maintenance

Disadvantages: During the time doing test PIM value – Passive Intermodulation with some
random sites we found some cells with high PIM interference caused to bad high drop rate,
bad call quality (specially uplink), bad coverage (power loss) .. And finally we found out the
reasons ( please refer the previous slide for details for each specific case)

•Some cells even are passed PIM interference threshold – 90 dBm, however
we are expecting PIM results should be less than -110 dBm as good one for
excellent network performance 
•Some Antenna, Feeder System aging over the time, performance
degradation caused by product materials & environment
• Poor workmanship : Loose contacts and rotating joints, cross cell,… etc
The cells with problems such as poor workmanship, aging products …caused to high interference
(specially for ICMB 3~5 level) which have been much improved performance after doing site audit.


THANK YOU
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