Improving wireless
Networks
Passive Intermodulation
Improving Wireless Networks
© Kaelus 2012. All rights reserved.
CONFIDENTIAL AND PROPRITARY INFORMATION OF KAELUS
About Kaelus
• Kaelus designs and manufactures a wide range of innovative RF and
microwave solutions for the wireless telecommunications sector
• Within Smiths Group we rebranded as Kaelus, four existing Smiths trading
entities into a single operating unit in 2010, while preserving the technology
and management of our individual companies
• Kaelus’ experience and understanding of the radio environment enables us
to excel by developing technically differentiated offerings that improve
network performance – Kaelus is an operating unit of Smiths Interconnect Microwave, within Smiths Group, plc.
PIM Test Instruments RF Conditioning Products Site Services
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Global Service & Support
Americas EMEA APAC
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What is Passive Intermodulation (PIM)?
CONFIDENTIAL AND PROPRITARY INFORMATION OF KAELUS
What is Passive Intermodulation (PIM) ?
PIM = Noise generated by the interaction between the multiple Tx signals and passive non-linear junctions in the RF path.
Increasing the received Noise floor thus reducing base station sites coverage and capacity.
f 1 f 2
f 1 +f 2 f 2 -f 1
2f 1 -f 2
2f 1 2f 2
2f 2 -f 1 3f 2 -2f 1
4f 2 -3f 1
3f 1 -2f 2 4f 1 -3f 2
Interference Interference
Desired
PIM generated products will affect received band (UL) by
CONFIDENTIAL AND PROPRITARY INFORMATION OF KAELUS
What is Passive Intermodulation (PIM) ?
For wireless operators
f 1 f 2
f 2 -f 1
2f1 –f2 3f 1 -2f 2
4f 1 -3f 2
Interference
GSM, UMTS, LTE, CDMA, WCDMA
DL - Downlink UL - Uplink
TX frequencies
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What is Passive Intermodulation (PIM) ?
f 1 f 2
f 2 -f 1
2f1 –f2 3f 1 -2f 2
4f 1 -3f 2
Interference
PIM depends on:
•Number of possible frequency combinations (more frequencies more possible combinations)
•The frequencies TX power ( + 1dBm Tx Power = + 2.5 to 3 dBm on PIM)
DL - Downlink UL - Uplink
TX frequencies
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PIM is getting more complex with
f 1 f 2
2f1 –f2 3f 1 -2f 2
4f 1 -3f 2
RX operator 1
By changing the TX frequencies the IM products change
DL - Downlink UL - Uplink
TX operator 1
f 1 f 2
2f1 –f2 3f 1 -2f 2
4f 1 -3f 2
RX operator 1
DL - Downlink UL - Uplink
TX operator 1
GSM900 Example
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PIM is getting more complex with
But now you have GSM900 with UMTS900 or LTE1800
f 1 f 2
2f1 –f2 3f 1 -2f 2
4f 1 -3f 2
RX operator 1
DL - Downlink UL - Uplink
TX operator 1
Not a lot of space to change TX frequencies, a UMTS carrier that normally is 5 MHz or LTE 10 MHz carrier and more combination possibilities
UMTS Or LTE Carrier
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PIM is getting more complex with
Networks evolution towards:
• Indoor or outdoor complex DAS systems (shared by several operators)
• Site sharing with multiple transmit carriers (same RF infrastructure for multiple operators)
• Multi-technology sites (GSM 900 MHz, GSM 1800 MHz, UMTS 2100, UMTS 900 MHz, CDMA 450, LTE800, LTE2600…)
Combining Unit
GSM 900GSM 1800WCDMA
OP
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de
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ad
180
0/W
CD
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900/1
800
Triplexer
RF Output ports
PSPS
PSPS
PSPS
PSPS
Outdoor
area
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PSPS
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AntAnt
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PSPS
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PSPSAntAnt
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Indoor
Area 1
Indoor
Area 2
Indoor
Area 3
Indoor
Area 4
Indoor
Area 5
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PIM Sources
Non-linear metal-to-metal contacts:
• Loose RF connectors.
• Poorly prepared RF cable terminations
• Improperly mated / misaligned parts
• Cracked / cold solder joints
• Loose mechanical fasteners (screws, rivets)
Traditional sweep (RL or DTF) testing many times does not identify these problems.
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First edition of IEC 62037 was published on 9/16/1999. (>12 years ago!)
Purpose:
To establish a standard test method for measuring Passive Intermodulation (PIM)
Provide a method to compare the PIM performance of different devices
Key recommendations of the specification:
Third Order IM products typically represent the worst case condition of unwanted signals; therefore measuring IM3 characterizes the DUT
PIM comparisons should be done at the same power level. (2x 20 W recommended for mobile communications systems)
Devices should be subjected to an “impact” or “movement” while PIM testing
PIM test specification IEC 62037
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IEC 62037 requires that devices be subjected to an “impact” or “movement” while PIM testing. Referred as “Dynamic” testing
Loose mechanical contacts in the field may not generate PIM until subjected to a future environmental stress (thermal cycling, ice loading, wind loading, etc.)
PIM level must stay below the specified maximum at all times during a dynamic test
FAIL
No tapping Tapping
PASS
Poor RF Connection
PIM tests must be dynamic
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PIM test process at cell site:
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KAELUS PPIM Solutions
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Summitek Instruments has been producing “bench top” PIM test systems for more than a decade
Summitek has delivered more than 800 BPIM systems worldwide
These systems have been used by RF equipment manufacturers to reduce PIM in their component designs
PIM testing is not new!
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What is relatively new is Portable PIM test equipment.
“Portable” PIM test equipment enables system level testing to be conducted at the cell site.
On site PIM testing reveals:
Installation workmanship issues
Component damaged during installation
Component damaged in transit
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• High Power – Premium
• Adjustable power (2 – 20W)
• Adjustable frequencies
• Rugged construction
• Integrated transit case
• Panel PC with touch screen interface, on-board reporting
PIM Test Equipment: iQA Series
CONFIDENTIAL AND PROPRITARY INFORMATION OF KAELUS -19-
• Reduces the time required to troubleshoot and repair a site
– Identifies the location of PIM sources that are present without dynamic testing
– Fix those first, then carry out dynamic testing
Benefits of RTF
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• Adjustable power (+0.1 to 20W)
• Highly portable and ruggedized design – ideal for top-of-tower testing
• Includes iPad Mini for safe, hands-free dynamic testing at the top of a tower
• Battery powered
• On board, touch screen interface available for local control
• Includes the Kaelus industry leading report generator
PIM Test Equipment: iPA Series
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iPA Passive Intermodulation Analyzer
• Highly portable and ruggedized design – ideal for top-of-tower testing
• Includes iPad Mini for safe, hands-free dynamic testing at the top of a tower
• IEC Specified Test Power: 2 x 20W
• Battery powered
• On board, touch screen interface available for local control
• Includes the Kaelus industry leading report generator
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Configurable and Ruggedized for Field Testing
• Designed for indoor, outdoor & tower top testing
• Lifting lugs at either end for hoisting and multiple
hanging and mounting orientations
• Rotating handles for any orientation
• Webbing straps on both sides for comfortable
hand carrying
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Wireless Remote Control
• Any Wi-Fi device with a web browser can connect and control the iPA – iPad Mini included with every unit
• Multiple devices can view data while testing as “viewers” or “master controllers”
• Safety master control functionality avoiding inadvertent RF transmission
• Field engineer at the base of a tower can control the unit while tower climber dynamically tests
• View multiple screens on the remote device, e.g. time trace and standard PIM
• iPA acts as an access point providing a secure wireless network utilizing WPA/WPA2 security
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© 2012 Kaelus Inc. All Rights Reserved
www.kaelus.com
Contact Us: Americas +1.303.768.8080
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