PIM - Inbuilding System Design Installation Strategies for LTE

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PIM: IN-BUILDING SYSTEM DESIGN &

INSTALLATION STRATEGIES FOR LTE

SPECIAL GUEST:

JULY 17, 2013

THE STANDARD for in-building network design and documentation

LEADING TECHNOLOGY & FIRST MOVER in a dynamic and fast-growing wireless market

9-YEAR-OLD Canadian company privately held

PRESENCE in all Americas, Europe, Middle-East, Africa, Asia and Oceania

TRUSTED BY 500+ CUSTOMERS in more than 80 countries

Phillip Chan Manager, InBuilding System Design

Rogers

ABOUT Rogers is a diversified Canadian communications and media company. They are one of Canada's largest provider of wireless voice and data communications services and one of Canada's leading providers of cable television, high speed internet and telephony services. Rogers is publicly traded on the Toronto Stock Exchange and on the New York Stock Exchange. www.rogers.com

John Beadles System Designer

Rogers

Marc Beranger Senior RF Interference Specialist

Rogers

IN-BUILDING SYSTEM DESIGN STRATEGIES FOR LTE

Phillip Chan, Manager, Wireless In-Building System Design

July 17, 2013

Introduction

PIM is a self-generated noise typically caused by defects in the antenna system, and by interactions of antennas with nearby objects

This noise causes: Reduced capacity Reduced coverage Slower data speed Dropped calls Shorter battery life

In-building DAS systems All channels run on the same antennas and cables Need for higher capacity, new technologies and DAS system sharing with

other operators result in potential PIM problems Frequency planning to avoid PIM is no longer viable This drives the requirement to minimize PIM noise

What is Passive Intermodulation?

Passive Intermodulation noise is the by product when radio signals mix

These products are combinations of sum and difference of the signals The center frequency of these resulting products are mathematically

predictable However, as the number of signals increase, the number of products

increase significantly

PIM is not related to return loss, VSWR or insertion loss!!! It cannot be detected by sweeps

PIM Noise Products

0 MHz Increasing FrequencyTX BandRX Band

b-a

2nd Order

2a-b3rd Order

2b-a3rd Order

2b-2a4th Order

3b-3a

6th Order3a-2b5th Order

4a-3b7th Order 3b-2a

5th Order

4b-3a7th Order

Actual PIM product amplitude cannot be predicted Varies on a case by case basis Decreases with the order of product

PIM product bandwidth is proportional to the order and the bandwidth of the fundamental frequencies 3rd order BW is three times the bandwidth of the fundamental 5th order BW is five times the bandwidth of the fundamental

Common Sources of PIM

Poor connector assembly Improper installation Damaged connector face Loose connections due to under torque

Metallic particles contamination In the plenum cable In the connector assembly In the connector face

Damaged cable Cut or broken conductor Damage to plating

Damaged antenna Broken pigtail Damaged connector face

Antenna Interacting with environment Rusty bolt effect

Manufacturing defects Bad solder joints Poor choice of materials

Physical damage Improper torque applied Forced fit

Why is PIM important for LTE?

LTE system link budget is based on Resource Block (RB)

One RB = 180 kHz (12 Sub Carriers X 15 kHz each)

Thermal Noise of one RB = -121dBm

Assuming eNode B receiver Noise Figure = 2dB, receiver sensitivity = -119dBm

Any PIM Noise generated in the DAS has to be significantly lower than -119dBm to not degrade receiver sensitivity

Required PIM Noise

LTE Uplink SINR vs. Throughput

SINR (dB) 10MHz UL Through Put (Mbps)0 4.11 4.82 5.63 6.54 7.45 8.56 9.57 10.78 11.89 13.0

10 14.211 15.412 16.613 17.714 18.815 19.716 20.517 21.218 21.819 22.220 22.4

High SINR required for LTE UL Performance LTE UL data throughput is much more

superior than HSPA UL Requires significant higher SINR than

HSPA Any degradations in receiver sensitivity

impacts throughput DAS system needs to have good PIM

performance to get full benefit of LTE

Note: the above table is based on simulation, and it is only for illustration purposes.

Strategies to Meet LTE PIM Performance Requirement?

Mitigate PIM Problems

Apply DAS design strategies to mitigate PIM problems Achieve PIM Performance Requirements

Follow installation and testing procedures to improve DAS construction, and to achieve PIM performance

Strive for Success and Doing it Better Apply real life experiences and learning from installation work Enhance / revise design strategies, and installation and testing procedures when applicable Share knowledge and experiences with the industry, and get feedback from other indoor DAS solution integrators and operators Influence the industry to further develop DAS products and testing equipment to facilitate doing it better

Types of DAS: Hi Power Active DAS 20W or more

Requires less number of remote amplifiers

Noise Figure from the active DAS components usually does not require high UL attenuation to mask the active DAS noise

Passive DAS PIM performance is important

Types of DAS: Med Power Active DAS ~28dBm

Requires greater number of remote amplifiers than hi power active DAS

Likely need more UL attenuation to mask the active DAS noise

Passive DAS PIM performance could be more relaxed due the required UL attenuation

Types of DAS: Low Power Active DAS ~20dBm

Requires large number of remote amplifiers

Noise Figure from the active DAS components does require high UL attenuation to mask the active DAS noise

Passive DAS PIM performance is usually not a concern due to the high UL attenuation

Types of DAS: Passive DAS

Passive DAS PIM performance is very important!

Radio Base Station directly drives the passive DAS

Why not only deploy Low Power Active DAS?

High UL attenuation required to mask active DAS component noise may also have a significant negative impact on the UL SINR

To maintain acceptable DL and UL path loss in-balance, base station needs to be interfacing the active DAS at much higher power. This places a huge demand on the required power handling and PIM performance of the radio base station interface equipment

Low Power Active DAS Uplink SINR Calculation Passive DAS Uplink SINR Calculation

Downlink Overall Path Loss Downlink Overall Path Loss

RBS Output Power 35dBm RBS Output Power 35dBm

CPICH Output Power 25dBm CPICH Output Power 25dBm

DAS Losses 0.0dB DAS Losses 25.0dB

Remote Antenna ERP 10.0dBm Remote Antenna ERP 10.0dBm

Remote Antenna CPICH ERP 0.0dBm Remote Antenna CPICH ERP 0.0dBm

CPICH Threshold -75dBm CPICH Threshold -75dBm

Pathloss (Antenna to UE) 75.0dB Pathloss (UE to Antenna) 75.0dB

Overall Pathloss 100dB Overall Pathloss 100dB

Uplink Overall Path Loss Uplink Overall Path Loss

Pathloss (UE to Antenna) 75.0dB Pathloss (UE to Antenna) 75.0dB

DAS Losses 0.0dB DAS Losses 25.0dB

DAS UL Noise Figure 39.3dB 85 Remote units DAS UL Noise Figure 0.0dB

DAS UL Gain 0.0dB DAS UL Gain 0.0dB

Rx Sensitivity -119.0dBm Rx Sensitivity -119.0dBm

DAS Noise from Uplink -81.7dBm DAS Noise from Uplink N/A

Required Attenuation 43dB Required Attenuation N/A

DAS Noise Level after Attenuation -124.7dBm

DAS Noise Level after Attenuation N/A

Overall Uplink Pathloss 118dB Overall Uplink Pathloss 100dB

UL and DL Path Inbalance 18dB UL and DL Path Inbalance 0.0dB

DAS Uplink Noise Figure Calculation

Noise Figure per Remote 20dB For 1 Remote

Noise Figure ALL Sectors 39.3dB For 85 Remotes

Uplink Gain ALL Sectors 0.0dB

Uplink Noise Power -81.7dBm

Low Power Active DAS Uplink SINR Calculation Passive DAS Uplink SINR Calculation

UE Tx Level Total 23.0dBm UE Tx Level Total 23.0dBm

UE Tx Level per RB 6.0dBm UE Tx Level per Subcarrier 6.0dBm

Uplink Pathloss 118dB Uplink Pathloss 100dB

UE Rx Level at RBS per RB -112.0dBm UE Rx Level at RBS per RB -94.0dBm

Uplink RX Noise Level -118.0dBm Uplink RX Noise Level -119.0dBm

Uplink SINR per RB 6.0dB Uplink SINR per RB 25.0dB

Uplink Datarate 9.5 Mbps Uplink Datarate 22.4 Mbps

Common Denominator: Passive DAS

How do we achieve the LTE PIM performance requirement with the passive DAS??

Design Strategies to Mitigate PIM Problems

Use PIM rated and proven DAS components See following slide for details

Keep transmit power low See following slide for details

Use simple and intuitive DAS vertical and horizontal topologies See following slides for details

Established DAS component naming convention Allow creation of automated testing spreadsheets based on component naming Standardized naming convention promotes common understanding of the DAS for the designers, installers and field operation and maintenance staff

DAS System PIM and Return Loss Performance Targets

System Construction Targets 850MHz: System PIM -114dBm @ 2 X +25dBm 1900MHz: System PIM -127dBm @ 2 X +35dBm System Return Loss 14dB

System Sharing Acceptance Targets 850MHz: System PIM -108dBm @ 2 X +25dBm 1900MHz: System PIM -121dBm @ 2 X +35dBm System Return Loss 14dB

Difference in construction and acceptance targets allows margin to ensure that the system will continue to meet the acceptance target as the DAS ages

Use PIM Rated and Proven DAS Components

Use DIN connector as much as possible instead of N-Type Will be further discussed in an upcoming slide

Lab experiments Rusty bolt effect Component testing

Manufacturer collaboration Connector design and installation Multi-band combining solution

Installer feedback Part of establishing DAS component proven performance

Typical passive DAS RF Component PIM Specs Splitter, combiners, connectors, and cables -155dBc @ 2 X 43dBm Indoor antennas are subjected to real life environment testing as the

manufacturer PIM spec is very different when testing in real life environment DAS head end multi-band combining solution -162dBc @ 2 X 35dBm

Keep Transmit Power Low

Radio Base Station output power = 35dBm composite per channel Typical minimum passive component PIM spec is -150dBc @ 2 x 43dBm. Assuming 2.5dB roll off, the PIM response at 2 X 35dBm is estimated to be -127dBm Lower power handling passive components could be used

Max power into the antenna = 15dBm composite per channel Significantly minimizes the rusty bolt effects when antenna interacts with its environment Typical design power is about 10dBm composite per channel, dependent on size of coverage area and environment in terms of rusty bolt effect

Vertical Design Organized by Floor

Organized vertically and horizontally

Construction and testing could be done on a per floor basis

Fault isolation on a per floor level can begin in the equipment room

1st Floor

2nd Floor

3rd Floor

4th Floor

5th Floor

6th Floor

Vertical Design Not Organized by Floor

Not organized vertically or horizontally

Construction and testing cannot be done on a per floor level

Fault isolation will require a lot of test equipment movement, possible access issues

Difficult to maintain from a Field Operation and Maintenance point of view

1st Floor

2nd Floor

3rd Floor

4th Floor

5th Floor

6th Floor

Horizontal Design Organized for Testing

Centralized location of splitter components

Can provide fault isolation to the branch level, depending on design

Minimizes the amount of test set movement, therefore less test labor time

Horizontal Design Not Organized for Testing

Decentralized location of splitter components

Maximizes the amount of test set movement, therefore more test labor time

Many cascaded components increase the points of failure for the floor

DAS TEST PROCEDURES AND REPORTING

John Beadles, System Designer, Rogers Communications

July 17, 2013

Goals for Testing

Goals for Testing Thoroughly test and exercise new DAS systems before acceptance

Prove that the system is being constructed properly Prove that the system passes PIM at acceptance Provide evidence that it will continue to pass in the future Prevent hidden quality control problems from popping up at the last minute

Get projects done on schedule, on budget Make the projects predictable So that they can be controllable Then cost controls can be implemented

Challenges Local contractors have little prior PIM testing experience Some contractors have little or no cellular construction experience at all Contractors not typically experienced with handling a lot of test data Need to streamline the testing process

Make it flow as much as possible so that milestones can be met Make no assumptions about previous contractor experience

Test requirements need to be flexible enough to accommodate all project types

Organized so that connector damage caused by testing is minimized

Types of Tests

PIM Testing Proves that the system is free of defects that would cause self-generated

noise back into the receivers

Return Loss Testing Ensures that the TX power doesnt get reflected back toward the transmitter Prevents early transmitter failure Ensures that RF power actually contributes to coverage

Insertion Loss Testing Verifies that the correct power tappers are installed Verifies that the power tappers facing the correct direction Ensures that each antenna will see the correct TX power

Distance to Fault Testing Provides individual cable lengths Finds damaged cables Helps prove that the contractor is building the system as designed

Test Procedure (Antenna & Individual Cable)

Pre-Install Antenna Testing PIM Test Ensures that the environment around the antenna wont contribute to failing

PIM at the antenna

Post Install Antenna Testing PIM Test Return Loss Test Ensures that the antenna performs properly in the installed position, and that

the antenna VSWR wont prevent the antenna from covering the area properly

Individual Cable Testing PIM Test Return Loss Test Distance to fault Ensures that each cable meets a standard quality spec Helps remove the cables as a source of problems when debugging other

issues Ensures that the cable is close to the length the system designer intended

Pre- and Post- Install Antenna Testing

Pre-Install antenna testing uses an antenna on a stick to verify the PIM environment in the area around which the antenna will be mounted

Post-Install antenna testing proves the antenna at that particular location

These tests have been a key to getting good antenna performance

System, Floor, Branch Level Components

Syst

emC

om

bin

er

Rad

ioR

adio

Rad

io

Floor 1

Floor 2

Floor 3

Floor 4

Floor 5

Floor 6

System Combiner Level Components

System Level Components

(multiple floors)

Floor Level Components(1 per floor)

Branch Level Components(multiple per floor, feeds antennas, no

more than 5 antennas per branch)

Riser Room

Test Procedure (Branches)

Branch Construction Test PIM test set attached to the entry point of the branch Low PIM terminations in place of antennas Test pass level -150 dBc @ 2x 43dBm when all jumpers and combiners are

attached. This test proves that the branch cabling is defect free

Branch Insertion Loss Test Signal generator attached to the entry point of the branch Power measurement taken at the output of each antenna jumper and is

compared to a predicted value. This test detects improperly installed power splitters and tappers. Also finds contractor modifications Antennas attached to each jumper after each test is complete

Branch Antenna PIM Test PIM test set attached to the entry point of the branch. Test is taken with all antennas attached PIM test power is set to the system design power at that point

Minimizes environmental PIM between the antennas and their surroundings Pass/fail is set to a dBm value based on receiver threshold, construction margin

Branch Construction & Testing

PIM Tester

S49-1 S49-2 S49-3C49-103

C4

9-1

04

C4

9-1

05

C49-101FloorFeeder

C49-102

C4

9-1

06

C4

9-1

07

S49-1 S49-2 S49-3C49-103

C4

9-1

04

C4

9-1

05

C49-101FloorFeeder

C49-102

C4

9-1

06

C4

9-1

07

Signal Generator

PIM Tester

S49-1 S49-2 S49-3C49-103

C4

9-1

04

C4

9-1

05

C49-101FloorFeeder

C49-102

C4

9-1

06

C4

9-1

07

Branch constructed and terminated with low PIM loads. Construction PIM test performed.

Branch Antenna PIM test performed with all antennas attached. If it passes, testing is complete on this branch and no other disconnects are allowed.

Stepwise insertion loss testing performed at each antenna connector, then the antenna is attached.

Power

Meter

Floor / Branch Organization

Each floor organized into a floor combiner network with multiple branches

Each branch, and the floor divider network, are tested as a unit

Minimizes the number of expensive low PIM test terminations that the contractor must purchase

SPT G2-3-3

SPT G2-3-8

SPT G2-3-12 SPT G2-3-5SPT G2-3-4 SPT G2-3-7 SPT G2-3-9 SPT G2-3-1

SPT G2-3-6 SPT G2-3-2

SPT G2-3-10 SPT G2-3-11

C G2_3-25

C G

2_3

-21

C G

2_3

-22

C G

2_3

-23

C G

2_3

-54

C G

2_3

-86

C G

2_3

-85

C G

2_3

-24

C G

2_3

-83

C G

2_3

-28

C G

2_3

-32

C G

2_3

-36

C G

2_3

-37

C G

2_3

-35

C G

2_3

-34

C G

2_3

-31

C G

2_3

-55

C G

2_3

-56

C G

2_3

-29

C G2_3-82 C G2_3-26

C G

2_3

-27

C G2_3-33 C G2_3-28

ANT G2_3-11

ANT G2_3-6 ANT G2_3-8 ANT G2_3-13 ANT G2_3-14 ANT G2_3-1

ANT G2_3-7 ANT G2_3-2 ANT G2_3-5

ANT G2_3-12 ANT G2_3-15 ANT G2_3-9 ANT G2_3-3ANT G2_3-14ANT G2_3-10

PIM Tester

Branch 1

Branch 2

Branch 3Branch 4

Branch 5

Floor Divider Network

Test Procedure (Floor & System Level)

Floor Testing Insertion Loss Test Return Loss Test PIM Test These tests, from the first unique floor level cable, ensures that all cables

and passive devices, are installed correctly and functioning properly

System (Sector) Testing Insertion Loss Test Return Loss Test PIM Test Ensures that the entire system, with the exception of the combiner, is

working and that all system level cables and passive components are installed correctly and functioning properly

System Combiner Testing PIM Test (Each Input) Verifies that the combiner and assorted inputs are working

Project Acceptance

Performed by Rogers Personnel Maximum accountability Eliminates communications problems with the contractor

System level PIM test Or performed by contractor while being observed by Rogers auditor

System level return loss test Or performed by contractor while being observed by Rogers auditor

Coverage testing Verify that all antennas are covering properly Finds accidental system disconnects

Delivery of all test results from contractor Reviewed & approved by the system designer

Contractor Deliverables

Completed test spreadsheet All values must pass Or have variances accepted by Rogers

PIM test measurements Screen shots (compiled into PDF)

Return loss measurements Screen shots (compiled into PDF) Data file (.DAT, .VNA)

Distance to fault measurements Screen shots (compiled into PDF) Data file (.DAT, .VNA)

Photographs Pre, post antenna location

Floor diagram markups

Automated Test Spreadsheet

Custom Developed by Rogers Identifies each test required from the contractor Used by project manager to cost out the testing Used by the contractor to define test parameters, collect test data Used by the system designer for QC monitoring, acceptance

Created by the system designer, custom for each project

Loaded by importing iBwave reports using Excel macros iBwave Link Budget Report

Provides insertion loss at any point Used to test power at each test point

iBwave Cable Routing Report Provides the cable lengths, connection points Used to calculate branch, system topology

Custom excel macro Generates one worksheet per test type Recalculates test powers based on desired test frequency Generates custom PIM test powers depending on design power Generates predicted insertion losses for branch, floor and system level tests Provides logic for pass/fail color coding for each test

Each worksheet contains: Sector, floor and Test Point ID Test powers Pass levels Predicted line lengths Insertion losses

From iBwave to the Automated Test Spreadsheet

iBwave Cable Routing Report

iBwave Link Budget Report Rogers Automated Test Spreadsheet

iBwave

Import

Examples of Antenna & Cable Worksheets

Post-install Antenna Worksheet

RF Cable Worksheet

Pre-install Antenna Worksheet

Test Cable Attn

(dB)

Test Pwr (dBm)

Test Pim (dBm)

Pass Level (dBm)

1 Ground Floor AP-A-01A 16 -114 5 21 -136.1 -1191 Ground Floor AP-A-01B 15 -114 5 20 -139.2 -1191 Ground Floor AP-A-02A 15 -114 5 20 -134.1 -1191 Ground Floor AP-A-02B 15 -114 5 20 -128.5 -1191 Ground Floor AP-A-03A 15 -114 5 20 -130.6 -119

Antenna Placement Test

Sector Floor Test IDDesign

Pwr (dBm)

850 PIM Pass Level (dBm)

850 Mhz PIM Test

Sweep-RL (dB)Test

Cable Attn (dB)

Test Pwr (dBm)

Test Pim (dBm)

Pass Level (dBm)

Test Cable Attn

(dB)

Test Pwr (dBm)

Test Pim (dBc)

Pass Level (dBm)

698-2700 mHz

1 Ground Floor A-01A 16 15 -114 -127 5 21 -129.5 -119 5 20 -133.7 -132 15.231 Ground Floor A-01B 15 15 -114 -127 5 20 -121.9 -119 5 20 -133.9 -132 17.741 Ground Floor A-02A 15 15 -114 -127 5 20 -124.2 -119 5 20 -133.7 -132 13.111 Ground Floor A-02B 15 15 -114 -127 5 20 -131.1 -119 5 20 -135 -132 17.451 Ground Floor A-03A 15 15 -114 -127 5 20 -132.8 -119 5 20 -133.8 -132 17.77

Sector

Installed Antenna Test Installed Antenna Test

Floor Test IDDesign Pwr 850 (dBm)

Design Pwr 2100

(dBm)

850 PIM Pass Level (dBm)

2100 PIM Pass Level (dBm)

850 Mhz PIM Test 2100 MHz PIM Test

850 MHz (2x43 dBm) 2100 MHz (2x 43 dBm) Design Plan Cable Predicted IL (dB) Measured IL (dB)

Sector Floor RF-Cable-ID Return Loss (dB) Length (meters) High Pim (dBc) High Pim (dBc) Length (meters) 2110 MHz 2110 MHz1 Ground Floor C1-44 34.20 2.63 -162.4 -155.7 10.00 1.6 0.461 Ground Floor C1-40 30.66 0.31 -158.9 -165.90 2.00 0.6 0.081 Ground Floor C1-48 35.85 0.50 -164.3 -162.5 2.00 0.6 0.121 Ground Floor C1-39 32.55 4.96 -158.3 -151.1 5.00 1.0 0.661 Ground Floor C1-42 29.18 0.01 -156.9 -157.7 2.00 0.6 0.161 Ground Floor C1-43 33.26 6.87 -151.8 -167.9 5.00 1.0 0.871 Ground Floor C1-46 35.52 1.00 -158 -164.5 2.00 0.6 0.191 Ground Floor C1-47 37.96 0.06 -158.3 -158.4 2.00 0.6 0.12

Sweep Test (1710-2155 MHz)

Test ID specifies the particular antenna. The AP prefix is used to separate PIM test screen shots

Test ID specifies the cable

Examples of Branch Worksheets Branch Construction PIM Worksheet

Branch Antenna PIM Worksheet

Branch Insertion Loss Worksheet

850 MHz (2x43 dBm) 2100 MHz (2x 43 dBm)

Sector Floor Test ID High Pim (dBc) High Pim (dBc)1 Ground Floor BP-C1-9 -153.2 -150.91 Ground Floor BP-C1-19 -158.2 -153.31 Ground Floor BP-C1-10 -160 -165.31 Ground Floor BP-C1-23 -171 -166.11 Ground Floor BP-C1-27 -167.5 -165.41 Ground Floor BP-C1-40 -170.9 -154.31 Ground Floor BP-C1-28 -162.1 -165.61 Ground Floor BP-C1-46 -158.3 -152.5

Measured Insertion Loss (dB)

Predicted Insertion Loss (dB)

Sector Floor Test ID 2110 MHz 2110 MHz1 Ground Floor BI-C1-9-C1-6 12.32 11.551 Ground Floor BI-C1-19-C1-20 12.40 11.551 Ground Floor BI-C1-9-C1-50 12.56 12.121 Ground Floor BI-C1-19-C1-11 12.06 12.311 Ground Floor BI-C1-9-C1-49 10.22 10.371 Ground Floor BI-C1-19-C1-26 9.90 10.57

Sector Floor Test ID

Test Power (dBm)

Test PIM (dBm)

Pass Level (dBm)

Test Power (dBm)

Test PIM (dBm)

Pass Level (dBm)

1 Ground Floor BAP-C1-9 15 -131.2 -114 26 -133.6 -1271 Ground Floor BAP-C1-19 15 -130.3 -114 26 -127.4 -1271 Ground Floor BAP-C1-10 15 -130.4 -114 23 -128.1 -1271 Ground Floor BAP-C1-23 15 -129.9 -114 23 -127 -1271 Ground Floor BAP-C1-27 15 -98.2 -114 15 -100.2 -1271 Ground Floor BAP-C1-40 15 -129.8 -114 15 -121.8 -127

850 MHz PIM Test 2100 MHz PIM Test

Test ID specifies the jumper entering the branch, exiting the jumper facing an antenna

Test ID specifies the jumper entering that branch. All antenna jumpers are terminated with low PIM loads.

Test ID specifies the jumper entering that branch. All antennas are installed at this point.

Examples of Floor Worksheets

Measured Insertion Loss (dB) Predicted Insertion Loss (dB)

Sector Floor Test ID 2110 MHz 2110 MHz1 Ground Floor FI-C1-4-C1-9 2.26 2.321 Ground Floor FI-C1-54-C1-19 2.25 2.321 Ground Floor FI-C1-4-C1-10 4.94 5.321 Ground Floor FI-C1-54-C1-23 4.98 5.321 Ground Floor FI-C1-33-C1-27 3.72 4.581 Ground Floor FI-C1-44-C1-40 3.72 4.581 Ground Floor FI-C1-33-C1-28 3.78 4.581 Ground Floor FI-C1-44-C1-46 3.78 4.58

Floor Insertion Loss Worksheet

Return Loss

Sweep-Return Loss(dB)

PIM

Sector Floor Test ID698-2700 mHz Test ID

Test Pwr (dBm)

Test PIM (dBm)

Pass Level (dBm)

Test Pwr (dBm)

Test PIM (dBm)

Pass Level (dBm)

1 Ground Floor FR-C1-4 13.74 FAP-C1-4 15 -130.9 -114 28 -130.1 -1271 Ground Floor FR-C1-54 13.81 FAP-C1-54 15 -129.8 -114 28 -131.5 -1271 Ground Floor FR-C1-33 11.67 FAP-C1-33 15 -108.1 -114 15 -112.8 -1271 Ground Floor FR-C1-44 14.84 FAP-C1-44 15 -100.1 -114 15 -127.3 -127

850 MHz PIM Test 2100 MHz PIM Test

Floor PIM & RL Worksheet

Test ID specifies the first single jumper entering that floor

Test ID specifies the input as the jumper entering that floor and the output of each power splitter facing the individual branches

Examples of System Worksheets

Return Loss Sweep-RL (dB)

SectorFloor Test ID Test Pwr

(dBm)Test PIM

(dBm)

Pass Level (dBm)

Test Pwr (dBm)

Test PIM (dBm)

Pass Level (dBm) Test ID

698-2700 mHz

1 Ground Floor SCP- 1-1900-1A 25 -114 35 -130.6 -127 SCR- 1-1900-1A 18.351 Ground Floor SCP- 1-1900-1B 25 -114 35 -127 SCR- 1-1900-1B 17.581 Ground Floor SCP- 1-2100-1A 25 -114 35 -127 SCR- 1-2100-1A 18.741 Ground Floor SCP- 1-2100-1B 25 -114 35 -130.8 -127 SCR- 1-2100-1B 18.711 Ground Floor SCP- 1-850-1A 25 -133.9 -114 35 -127 SCR- 1-850-1A 17.71 Ground Floor SCP- 1-850-1B 25 -122 -114 35 -127 SCR- 1-850-1B 17.74

850 MHz PIM Test 1900 and/or 2100 MHz PIM Test

System Insertion Loss Worksheet

System PIM & Return Loss Worksheet

System Combiner Worksheet

Test ID specifies each input port on the system level combiner

Test ID specifies the jumper coming out of the system combiner, facing the DAS network

Test ID specifies the input as the jumper coming out of the system combiner and the output of the power splitter facing the floor

Thats a Lot of Testing!

Yes it is! But it is necessary to ensure that all the parts of the DAS are working and will

continue to work

Cant some of the testing be eliminated? Sure, but eliminating any part increases risk

Some problems may not be found until system turn-up or later Can the contractor find and fix problems in a timely fashion?

Do they have previous experience? Are their construction and test crews experienced? Does the contractor have personnel turnover issues?

What is the added cost of finding problems late? Scheduled access restrictions Cost of security, cleaning crews, elevator access Contract requirements Customer, property manager relationships

What is the cost of a PIM problem found later in the system life cycle? After other operators are added? Maintenance cost?

May be possible to reduce some testing As confidence in contractor competence increases As DAS components become more resistant to PIM Antenna environmental PIM not likely to ever go away

REAL WORLD DAS PIM TESTING

Marc Beranger, Sr. RF Interference Specialist, Radio Engineering

July 17, 2013

In-Building DAS Construction Testing

Real World PIM Challenges Highlight some of the issues we have had through nearly two years of

developing our design and test procedures.

Build then Test VS Test as we Build Will provide reasons why we approach testing the way we do

DAS Performance Achievements Examine the progress we have made to date

DAS Specific Test Equipment Focus on PIM testing equipment and the requirements necessary to properly

test DAS systems

Real World PIM Challenges - Components

PIM Rated Components Splitters, Tappers, Antennas

All must be PIM rated Combiners near the radio may need better PIM specs due to LTE noise

requirements Typical: -150 dBc @ 2x 43 dBm (-107 dBm) Our spec: -162 dBc @ 2x 35 dBm (-127 dBm)

Connectors Some field installable connectors work well on foam filled outdoor cable But can fail dynamic PIM because of differences in conductor thickness

Factory Jumper Cables Have been known to fail dynamic PIM

Be prepared to do quality control checks on all components, because manufacturing accidents do happen

Real World PIM Challenges - Training

Contractor Training and Feedback Rogers provides mandatory contractor training, including:

Connector installation training (supplied by the connector vendor) Overview of PIM relating to DAS Lessons learned from previous projects Review of test procedures and deliverables Review of test data collection Hands on training in pre-install antenna location procedure

Rogers constantly updates this training based on feedback from contractors

Real World PIM Challenges Connector Assembly Proper Installation and assembly of connectors and cabling

Plenum cable is hollow. Metal particles can fall inside and create PIM. During earlier projects we have had to replace almost all cable on several floors to clear PIM

Hack saws and files MUST NOT be used! PVC pipe cutter provides a clean cut. Clean cable ends during with isopropyl alcohol during cable prep Cover unterminated cable ends with plastic caps or electrical tape Bad flares, ragged cuts, plating damage can result in poor PIM

Real World PIM Challenges - Contamination

Metal wears off the threads during each connection and stick to the threads or conducting surfaces. If this metal gets in between the conducting surfaces, PIM noise can be created.

Clean with alcohol before each connector mating.

Clean any protective caps for adapters

CLEAN ALL CONNECTORS ALL THE TIME!!

Using a swab and a stick, wipe between the inner and outer connector

Next wipe the insulator and metal surfaces

Using the clean side of the swap, use your finger to wipe the tops of the inner and outer conductor

Real World PIM Challenges Cleaning

Real World PIM Challenges Connector Torque

Connectors must be correctly torqued to pass PIM

Undertorque results in unstable connections, causing failures

Overtorque can result in damage to connectors, causing failures

Experience shows that good PIM performance with N connectors is possible using slight overtorque.

7-16 DIN connectors are strongly recommended wherever possible

Test cables and adapters must be monitored for torque related damage

This connector is ok Broken

Broken

Broken

Real World PIM Challenges - Connector Stress

The system to the right was secured to the wall with cable clamps, drywall anchors

These connectors would fail PIM erratically

The system was redesigned with secured power dividers and stress relief loops

PIM issues were dramatically reduced

Real World Challenges - Rusty Bolt PIM Noise PIM Noise can be created by RF interaction between the antenna and conductive

objects in the environment outside the antenna system. PIM sources can be both below and above the antenna.

This is unpredictable but using general guidelines and the antenna pre-install procedure, we can find antenna locations that limit the impact of environmental PIM

850 MHz frequencies tends to be more reactive then AWS/PCS frequencies within the environment. This is reflected in our system level test specs AWS/PCS -127 dBm at a test power of 2x35 dBm 850 -114 dBm at a test power of 2x25 dBm

POTENTIAL PIM SOURCES Electrical cabling

Ceiling mounting hardwareLighting control devices

ABOVE ANTENNA

BELOW ANTENNAPOTENTIAL PIM SOURCES

Suspended lighting or pipingMetal on metal contact points

Mounting Surface

Various sources of Rusty Bolt PIM

Suspect components Ballast in fluorescent lights DC power supplies in LED lights Steel hardware Heat Sensors

Keep antennas at least 1 metre away

Generally an open concrete ceiling has better environmental PIM response than a suspended ceiling

Case Study-Foil backed insulation & Steel Studs

PIM noise observed in antennas mounted on walls with foil backed insulation

Remove insulation from behind antennas

Install antennas between steel studs where possible.

Relocate occurred on most of the floors where the antenna was positioned in this location

FRONT VIEW BACK VIEW

Case Study-RF Absorber Material

Can be helpful when PIM source is above the antenna.

If you lower your antenna during pre-install PIM testing and the PIM improves then your prime PIM source is likely above the antenna.

This is not a solution for all situations but it is one more tool in the toolkit.

Expensive!

Build then Test vs. Test while Building

Build then Test (then fix as required) Advantages

Faster, cheaper to construct, if number of defects is small (unlikely with PIM) Disadvantages

Large number of defects can dramatically slow fault finding (likely) If fault finding not built in to schedule, likely to result in schedule, cost overruns Schedule overruns likely due to probable high number of PIM failures Uncaught contamination issues led to whole floors of cables being replaced

Test while Building Advantages

Contractor has immediate quality control feedback Operator can monitor contractor quality Assurance that construction is correct before moving on in restricted access situations Finds common defect types early

Environmental PIM Manufacturer defects Technique errors Faulty equipment

Disadvantages Slower, more costly to construct (but built into project)

DAS Performance Achievements

Pool of contractors that build and test our DAS systems increasing Now contractors that had no previous DAS experience being successful Continue to monitor existing contractors to improve performance and

incorporate their feedback in testing procedures.

The most recent acceptance audits are now completed in one visit. Initially we struggled to meet acceptance specifications, with many return

visits.

Typical low PIM DAS construction effort of a single floor of an office initially took up to 2 weeks to test and install, now we can do this in less than a week. 8-12 antennas, 20,000 sq. ft.

DAS Specific Test Equipment Recommendations

PIM Interaction between the antennas and the environment drives design requirements for lower TX power per antenna Non linear response prevents testing of antennas using scaled power, PIM results PIM testing needs to be done at system design powers, PIM acceptance values need to be related to receiver thresholds Drives a need for PIM test eqpt with lower test powers, better sensitivity, lower residual PIM

Test reporting is a key to successful PIM quality control PIM testing of macro site PIM testing may generate tens of reports a week DAS PIM testing may generate hundreds of reports a week, for weeks at a time To improve productivity, PIM test eqpt needs better ways to manage reports Test spreadsheet already defines test IDs, test parameters Allowing upload of test spreadsheet into PIM test set would eliminate a lot of operator data

entry Ethernet capable, remote operation?

Test equipment connections Test equipment uses N, DIN connectors Connectors wear with each connect / disconnect cycle, require cleaning each time DAS testing has hundreds of connect / disconnect cycles a week, for weeks at a time Need a better, non-threaded on test equipment for time savings

Hands-on, DAS specific training needed from PIM test set manufacturers Must include in-building environmental antenna effects

DAS Specific Test Equipment Recommendations

Ideal PIM Test Set Test Power Range

+43 dBm to +20 dBm in 1 dB increments (minimum) +43 dBm to +10 dBm in 1 dB increments (desired) +43 dBm (20w) power needed to for component acceptance testing Adjustable low power needed to avoid environmental interaction with antennas

Sensitivity, Residual PIM -170 dBc (-127 dBm) @ 2x43 dBm -157 dBc (-137 dBm) @ 2x20 dBm (minimum) -147 dBc (-137 dBm) @ 2x10 dBm (desired)

Networkability Run PIM test sets with multiple frequency bands from one terminal Automatic download to test results to one terminal

Ability to upload test point definition Preset test ID, test powers, frequencies, pass levels Eliminate extra operator data entry

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PRESENTERS: Phillip Chan Marc Beranger John Beadles www.rogers.com