Best Practices of Interference Management- Sep 2016

1 © 2016 Viavi Solutions Inc. www.viavisolutions.com 1 © 2016 Viavi Solutions Inc. www.viavisolutions.com 1 © 2016 Viavi Solutions Inc. www.viavisolutions.com

‘Why’-’What’ and ‘How’ of Interference

Hunting Atul Deshpande

Makassar, Indonesia

[email protected]

13 Sep 2016

Best Practices of

Interference

Management

http://www.viavisolutions.com/



mailto:[email protected]



Agenda

• Understand ‘What’- What is Interference Management?

- What’s Interference Hunting

- Spectrum Cleaning Vs Interference Hunting

• Understand ‘Why’- Why hunt Interference?

- KPI and User experience Challenge

• Cellular Interference Issues

- Interference MATRIX (Cellular Operator)

• Understand ‘How’- How to hunt Interference Source?

- Symptoms

- Geography

- Preparation for IH

- Spectrum knowledge

- Statistics

- Site Level investigation

• 3 Steps in Interference Management

- Detect

- Identify

- Locate





Features

CellAdvisor BASE STATION ANALYZER SIGNAL ANALYZER RF ANALYZER CABLE & ANTENNA ANALYZERS

JD785B JD745B JD788B JD748B JD786B JD746B JD726C JD725C JD724C JD723C

Cable & Antenna Analysis

5MHz to 6GHz

5MHz to 4GHz

5MHz to 6GHz

5MHz to 4GHz

5MHz to 6GHz

5MHz to 4GHz

5MHz to 4GHz

100MHz to 2.7GHz

Insertion Gain/Loss O O O O O O O S

Bluetooth, WiFi, Web Control

O O O O O O O O O O

RF Power O O O O O O O O O O

Optical Power O O O O O O O O O O

Fiber Inspection O O O O O O O O O O

Cloud Services O O O O O O O O O O

Spectrum Analysis 9KHz to

8GHz 100KHz to

4GHz 9KHz to

8GHz 100KHz to

4GHz 9KHz to

8GHz 100KHz to

4GHz

Interference Analysis O O O O O O

PIM Detection S S S S S S

Signal Analysis O O O O

Interference Analysis O O O O O O

RFoFiber Interference O O O O O O

RFoCPRI BBU-Emulation

O O O O O O

Signal Analysis O O O O

LTE DAS Test O O O O

RF Test Portfolio Wireless Field Test Solutions O: Optional S: Standard : Not Available





CellAdvisor Fundamentals and Support

• Updating unit FW: http://celladvisor.updatemyunit.net

• Add-on Software (download from above link and install on Laptop):

- JDViewer (Viewing Spectrum Logs)

- JDMapCreator (For Map Creation on Google for Interference Hunting)

- JDRemote (For Remote monitoring)

• CellAdvisor JD700B User Manual

• Viavi CellAdvisor Page (Complete Portfolio and much more):

- http://www.viavisolutions.com/en-us/celladvisor

• Viavi Signal Analyzer Page (Brochure/Data Sheet/App Note/WhitePaper):

- http://www.viavisolutions.com/en-us/products/network-test-and-

certification/cell-site-test/celladvisor-signal-analyzers-jd748b-jd788b

• For support:

- Get in touch with Local Viavi Partner for immediate assistance.

- Drop me email: [email protected]




http://celladvisor.updatemyunit.net/








http://www.viavisolutions.com/en-us/celladvisor










http://www.viavisolutions.com/en-us/products/network-test-and-certification/cell-site-test/celladvisor-signal-analyzers-jd748b-jd788b





































CellAdvisor Learning- Bookmarks!

• To learn more about Viavi InterferenceAdvisor Automated Solution:

- http://www.viavisolutions.com/en-us/interferenceadvisor

• InterferenceAdvisor Brochure

- http://www.viavisolutions.com/sites/default/files/technical-library-items/interferenceadvisor-

br-nsd-tm-ae.pdf

• InterferenceAdvisor Data Sheet (providing part numbers and specs)

- http://www.viavisolutions.com/sites/default/files/technical-library-items/interferenceadvisor-

ds-nsd-tm-ae.pdf

• Interference Hunting White Paper

- https://velocity.viavisolutions.com/servlet/JiveServlet/previewBody/4346-102-2-

6628/InterferenceHunting-wp-nsd-nse-ae.pdf

• Webinar on interference hunting

- http://content.rcrwireless.com/viavi_interference_hunting_webinar




http://www.viavisolutions.com/en-us/interferenceadvisor



http://www.viavisolutions.com/sites/default/files/technical-library-items/interferenceadvisor-br-nsd-tm-ae.pdf













http://www.viavisolutions.com/sites/default/files/technical-library-items/interferenceadvisor-ds-nsd-tm-ae.pdf





























6 © 2016 Viavi Solutions Inc. www.viavisolutions.com 6 © 2016 Viavi Solutions Inc. www.viavisolutions.com 6 © 2016 Viavi Solutions Inc. www.viavisolutions.com 6 © 2016 Viavi Solutions Inc. www.viavisolutions.com

Fundamentals-

Interference and

management






What is Interference and Interference Hunting?

• Interference (between radio signals) is, any RF Signal

(Modulated/CW/Baseband), oscillating at certain frequency and amplitude,

collides with another RF Signal with same frequency, (different) amplitude

@certain location.

• Interference Hunting is ‘systematic engineering approach’:

- To identify, detect and locate, RF Signal sources, infringing licenses bands

operations, at particular geography/location/area.

- Both Interferer Signal and Interfered signal can be genuine signals, sharing

similar licensed spectrum @particular location.

- New Allotted Spectrum means ‘Possibility of Interference’.

- Most of the allotted spectrum to Cellular Operators to launch new services is,

either refarmed by another Cellular Operator or service or by non-Cellular

Operators (Defense establishments, ISP, Broadcasters).





Introduction to RF Interference

SPECTRUM VISUALIZATION

• Spectrum is shared among an increasing number of licensed and unlicensed transmitters (Cellular, Cable TV, WiFi, AM/FM,

etc.) possibly causing interference among transmitters.

• The RF environment is also polluted by unwanted signals such as spurious, intermodulation, jammers, amplifiers and

elements that generate RF noise such as transformers and industrial machinery.

• Interference negatively affects services in terms of network coverage and mobile capacity.

• There are three main aspect for Interference analysis: Detection, Identification and Location.





Spectrum Cleaning Vs Interference Hunting

• Spectrum Clearing/Cleaning

- Greenfield/Brownfield network launch

- Launch of New services over refarmed

spectrum

- Mostly done Pre-launch of Network (Pre-

SCFT) or During Site Installation/AT

Phase.

- Drive testing with Receivers/Scanners

- Measure UL RSSI (measure of Clean

Spectrum).

- High RSSI (not clean Spectrum)

• Interference Hunting

- Specialized activity to ‘Detect- Identify-

Locate’ Interfering Sources

- Step 2 of High UL RSSI or Spectrum

Clearing drive.

- Network Launch/Planning Stage or

Optimization Network stage.

- Spectrum Analyzers with set of Antennas

(Omni and Directional).





Interference MATRIX

High Possibility

Highest Interest

Med to high Possibility

Curious Case

High Possibility

Not of our Interest

Not of our Interest

Interfered

Systems Cellular

Non-Cellular

Cellular Non- Cellular

Interfering Systems





• External Interference

- Radio Signal Generators, outside

Cellular Ecosystems.

- E.g. Cellular Repeaters, HAM Radios,

Police Wireless Transmitters etc.

• Interference Management Solution

can be deployed to identify ‘External

Interferences’

‘External Interference

Hunting’

External Interference Vs Internal Interference

• Internal Interference

- Radio Signal Generators, inside Cellular

Ecosystem of Opco.

- E.g. Faulty Hardware (RRU),

PIM/Intermod Generating Components

etc.

• Interference Management Solution

might be necessary but not sufficient

to address these.





• Interference affects ‘UL’ the ‘MOST’

- UL is more sensitive to Interference,

being low power transmission (UE to

NodeB)

- UL is un-controlled RF

- Better ‘Gain’ (to Interference) due to high

gain Antenna @Site.

- Coverage is UL limited (not DL)

- Asymmetric Traffic (UL Importance)

- Limited Optimization possible on UL

‘More Incentives to Interference

Hunters’

Why hunt Interference?





UPLINK

DOWNLINK

TX Power:

No limit (+43dBm)

RX Sensitivity:

-101.5 dBm

TX Power:

+23 dBm

RX Sensitivity:

-94 dBm

• Interference can affect downlink (cell-site) and

uplink (mobile).

• The uplink is more sensitive to interference due

to mobile transmission restrictions (23dBm or

0.2W).

• Interference can be generated by:

‒ External sources of the cell-site (noise generators,

other transmitters)

‒ Internal sources (spurious, harmonics, passive

inter-modulation).

Introduction to RF Interference Cellular Networks – Uplink Sensitivity

UPLINK AND DOWNLINK VISUALIZATION

CDMA UPLINK INTERFERENCE WCDMA UPLINK INTERFERENCE LTE UPLINK INTERFERENCE





Cellular Interference Issues

• Downlink (eNodeB to UE)

- DL more controlled

- DL Vs DL

- Inter RAT

- Intra RAT

- Neighbours

- Physical Optimization

- Parametric Optimization

- Power/Coverage/Capacity

• Uplink (UE to eNodeB)

- UL more uncontrolled

- UL Vs DL

- UL of eNodeB1 Vs DL of eNodeB2

- UL vs UL

- UL of eNodeB1 Vs Cellular

Repeaters

- UL Power Control

- UL Optimization?





Why Hunt Interference?

• Interference Hunting, as part of Network Optimization, is on-going process

• Network evolves-> Interference evolves

• Need improved process and tool to mitigate Interference

• Interference not-managed leads to:

- KPI Degradation at Site/Cluster level

- RRC Connection Setup, eRAN Connection Setup, Call Setup, UL throughput,

UL Quality (SINR/RSRQ), UL/DL Capacity, Call muting

- Degradation of Customer experience on Network (Inconsistent performance)

- Revenue/RoI Loss to Opco (Traffic churn)

‘Interference Hunting is full time designation is some of the

Opcos across globe and becoming more of so elsewhere’





• OSS/NMS Alarms

TRRIGERS!

• RF KPI Degradation

• UL RSSI

• UL Throughput

• Fix/Flexible PRB

SINR issues

• CSR Issue

• Call muting

• Customer Complaints

• Increased customer

complaints in certain

areas (due to

coverage/speed)

• In addition Opco are using GEO SON solutions to identify Interference Issues





• The location of Interference is a lengthy process based on directional testing at three

different positions and performing triangulation to find the intersection area where the

interferer is located.

Introduction to RF Interference Location

INTERFERENCE LOCATION VISUALIZATION





Best Practices

- Answer ‘How’






Best Practices

•Internal / External

On-site Analysis

•Drive large area

Detect Identify

•Optimize EagleEye

•Location Estimation

Drive Around

•Pinpoint source

•Antenna Advisor

Locate

•Report generator

Report

1. Start with the problematic site (e.g. eNB sector)

2. Drive around relatively large area to understand the problem details & the interferers characteristics

(e.g. intermittent, single tone, multi peaks, oscillating, band noise, etc)

3. Once the interferers detected, then narrow down more to find what frequency or band need to be used

for EagleEye

4. Optimize EagleEye setting using 3 different tracking modes (RSSI, Channel Power and Peak Power)

5. Drive in the direction of the strongest signal to estimate the most probable location of the source (Circle

indication, Directions & Navigations)

6. Manually pinpoint the source using AntennaAdvisor within the area estimated by EagleEye

CellAdvisor RFoCPRI

& RFoOBSAI

AntennAdvisor with

Log periodic antenna

EagleEye

Report Generator

EagleEye Spectrum &

Spectrum Control

EagleEye Location Estimation

(RSSI, Ch PWR, Peak PWR)





Cell Site Optimization Signal Analyzers

O: Optional S: Standard : Not Available

PERFORMANCE

RF and Optical Power

Fiber Inspection

Spectrum Clearance

AIR INTERFACE

CONNECTIVITY

Signal Analysis

PERFORMANCE RFoFiber

Interference Analysis &

BBU-Emulation

Signal Analysis

Interference Analysis

Features

CellAdvisor SIGNAL ANALYZER

JD788B JD748B

Cable & Antenna Analysis

Insertion Gain/Loss O O

Bluetooth O O

RF Power O O

Optical Power O O

Fiber Inspection O O

Cloud Services O O

Spectrum Analysis 9KHz to 8GHz 100KHz to

4GHz

Interference Analysis O O

PIM Detection S S

Signal Analysis O O

Interference Analysis O O

RFoFiber Interference O O

RFoFiber BBU Emulation O O

Signal Analysis O O

LTE DAS Test O O





RF

oF

ibe

r RFoFiber technology verifies CPRI and OBSAI control signals and analyzes user plane

traffic or RF (IQ) signals.

Cell Site Optimization RFoFiber Interference Analysis

Cable &

Antenna

Analysis Spectrum /

Interferenc

e

2G, 3G,

4G Signal

Analysis

Amplifier/Filter

Insertion G/L

GPS Positioning

Sync & Timing

Fiber Inspection

I/O Interface

RFoFiber

RF

signal

(RF)

CPRI

link

Framing

Grouping

Mapping

Sampling

RF

Signal

Analys

is

NEM Profiles

RFoFiber (CPRI or OBSAI) : Multi-Radios





Interference

Detection






Cell Site Optimization RFoFiber Link Monitoring

BBU

α β γ

(Sectors)

Optical Coupler

α β γ (Sectors)

Coupled

CPRI link

CellAdvisor RFoCPRI or

RFoOBSAI

Coupled Monitoring

RRH

CPRI

Status

Optical

Power

CPRI Link Status and Optical Power





RFoCPRITM Interference Analysis

• Interference Analysis with RF Source (Multi-Carrier

WCDMA example)

Cell Site Optimization RFoFiber WCDMA Analysis (RFoCPRI & RF-Source)

RF Source @

837.5MHz RF Sources @

1906.5MHz

CellAdvisor

RFoCPRI

Copper

Fiber

Optic

al

Splitt

er

FIBER RX

RRU

BBU

RF

Sourc

e

UMTS

5MHz Channel

Bandwidt

h

3.84MHz Transmis

sion

Bandwidt

h

CPRI

CONTAI

NER

Dual Spectrogram – Active Analysis of Two Carriers

WCDMA Multi-Carrier Identification





RFoCPRITM Interference Analysis

• MIMO Test (Diversity Imbalance): Spectrum Analysis

and Spectrogram

Cell Site Optimization RFoFiber MIMO Test (Diversity Imbalance)

Antenn

a 2

Antenn

a 1

Dual Spectrum Analysis – Antenna 1 (Active) and Antenna 2 (Active)

Active Spectrum Analysis of Dual Antenna or Dual Carrier

Antenna 1 Antenna 2

Dual Spectrogram – Active Analysis of Two Antennas

RFoCPRI Dual Spectrum (MIMO) RFoCPRI Dual Spectrogram (MIMO)





RESOLUTION

BANDWITH

(RBW)

RBW = 1 MHz RBW = 100 KHz RBW = 10 KHz RBW = 1 KHz

TRACE

SIGNAL UNDER

TEST

Detecting Interference Measurement Techniques – Overview

5. RESOLUTION BANDWIDTH

4. FREQUENCY SPAN

1. A

TT

EN

UA

TIO

N

2. P

RE

AM

PL

IFIE

R

3. M

IN &

MA

X T

RA

CE

S

ATTN: 10dB

PREAMP: OFF

RBW: 300KHz

ATTN: 0dB

PREAMP: ON

RBW: 10KHz

SPECTRUM ANALYSIS

1. Attenuation. Typically

interference testing is

conducted at low power

connection points such as

antennas for which any

signal attenuation should be

removed.

2. Preamplifier. Low power

signals such as uplink will

require amplification (e.g.

10dB)

3. Min & Max Traces. Trace

control such as minimum

hold will effectively capture

interference in variable

(uplink) environments.

4. Frequency Span. A narrow

frequency span will improve

measurement time.

5. Resolution Bandwidth. A

low resolution bandwidth will

increase sensitivity and

signal detection.

Basic measurement techniques for interference testing with spectrum analysis.





RBW: 10KHz

Interference

Detected

RBW: 300KHz

No interference

Detecting Interference Measurement Techniques – RBW and VBW

SPECTRUM ANALYSIS - OVER THE AIR TEST

SPECTRUM ANALYSIS

GSM WCDMA CDMA

Interferences are better uncovered by: Improving sensitivity: lowering the instrument’s resolution bandwidth (RBW).

Eliminating trace noise: narrowing the video bandwidth (VBW) filter.





Signal

detection with

Maximum Hold

Signal trace

with spectrum

analysis

Signal trace

with minimum

hold

Detecting Interference Measurement Techniques – Maximum and Minimum Hold

SPECTRUM ANALYSIS

GSM WCMDA

SPECTRUM ANALYSIS - OVER THE AIR

Maximum and minimum power tests properly characterize variable signals: Signal level signature: holding maximum power will characterize time domain signals (GSM).

Noise level signature: holding minimum power will characterize noise floor (uplink).





Detecting Interference Measurement Techniques – Gated Sweep

POWER

TIME

FREQUENCY

TDD Uplink

Interference

TDD DOWNLINK TDD UPLINK

Time division duplex systems such as WiMAX-TDD and LTE-TDD share the same frequency for uplink

and downlink signals based on transmission time.

Interference detection in TDD signals is made in time-domain analysis with gate-sweep testing

enabling test-time control for uplink interference detection.

GATE-SWEEP ANALYSIS

TDD – Time Division Duplex (LTE-TDD or WiMAX)





Detecting Interference Intermittent Signals

Intermittent

Interference

SPECTROGRAM

WCDMA

CARRIERS

CDMA

CARRIERS

Long-term test Spectrogram test constantly

registers the spectrum over

extended periods of time.

Intermittent interference The spectrum is presented in a

color scale based on the

signal’s power level making it

easy to detect intermittent

signals.

Interference analysis Spectrogram records maintain

time and location for further

interference analysis.





• What is PIM?

Passive Inter-Modulation (PIM) is interference (uplink)

caused by signals derived by the combination of two or

more carriers (downlink) transmitted on a single

nonlinear feed-line.

• What causes PIM?

Nonlinearities in feed-lines can be created by improper

connections, contaminants, partial discontinuities

(cracks or dissimilar metal joints) or improper material

(ferromagnetic such as iron, nickel, cobalt).

Detecting Interference Passive Intermodulation

UPLINK

DOWNLINK

COMBINER

2G RADIO 3G RADIO

DOWNLINK

UPLINK

PIM

PIMIM3 = 2 x F1GSM – F2WCDMA = 2 x 869.2 – 891.6 = 846.8

WCDMA

G

S

M

FREQ

POWER

FREQ (MHz)

CH

869.2

128

891.6

4458

849 824

P

I

M

846.8

UPLINK

PIM





• PIM Detection

PIM detection is the first test made in isolated sites that are

experiencing interference.

A sensitive spectrum analyzer (< -120dBm noise floor) is

capable of detecting the presence of PIM, the test procedure

is as follows:

1. Connect the instrument to the Radio (RX) port.

2. Set the instrument to high sensitivity (-130dBm) at the uplink frequency,

preamp ON and RBW to 3KHz.

3. Stop transmission of F1 (GSM) and capture it as noise reference (PIM

not created).

4. Transmit F1 (GSM) and capture (min-hold) test to detect PIM in relation

to the reference test.

Detecting Interference Passive Intermodulation

DOWNLINK

COMBINER

2G RADIO 3G RADIO

PIM

JD745A

WCDMA

FREQ (MHz)

POWER

891.6 849 824

UPLINK G

S

M P

I

M 869.2 846.8

PIM

WCDMA

FREQ (MHz)

POWER

891.6 849 824

UPLINK

RX-MON





Interference

Identification






Identifying Interference Signal Interference – Identifier

Interference identifier provides information of the possible signals that can be

transmitted on the frequency under test.

SIGNAL ANALYSIS

Interference WCDMA Identifier

INTERFERENCE ANALYSIS





Identifying Interference Signal Analysis

Interference

WCDMA

SIGNAL ANALYSIS – GSM (SITE 36)

SPECTRUM ANALYSIS

Signal analysis demodulates interference to promptly identify its characteristics,

including site identification, expediting resolution.

SIGNAL ANALYSIS – WCDMA (SITE 267)





Interference

Location






Interference Drive Thumb Rule!

Mount the Omni Antenna on top of car and connect it to CellAdvisor through

BPF (of Band of Interest) and drive through suspected area.





Locating Interference GPS Triangulation

INTERFERENCE FINDER

Interference location requires testing with a directional antenna and performing a 3-point test

from which triangulation can be derived.

Locating interference can be a time consuming process, for which automated triangulation based

on GPS and reference mapping significantly reduces interference location time.

DIRECTIONAL RECEIVER

3-POINT TEST





Cell Site Optimization AntennaAdvisor Overview

Antenna Advisor

Test Activation

Sensitivity Low Noise Amp

RF

Performance

Location GPS Antenna

Test Results

Radar

Directivity

Radar Chart

CellAdvis

or

Location

Expedite Resolution: Interference Finding

Interference Finer





Cell Site Optimization Cloud Service : StrataSync

Manages and tracks test INSTRUMENTS

Collects RESULTS from the entire network

NOTIFY users of new firmware releases, and options.

StrataSync

*Estimated Release Apr-2014

Asset

Management

Data

Management

Viavi Updates





• Fronthaul

• Fiber Feed-line Optical Power and Fiber Inspection

• Trouble-Shooting

• PIM Detection

• DAS Comparison Test

• Performance

• Signal Analysis (Modulation Quality)

• LTE Broadcast (MBMS)

• LTE Advanced (Carrier Aggregation, MIMO 4x)

• Optimization

• Coverage Mapping

• RFoFiber

• Cloud Services

• Automatic Tests

• Asset Management

• Data Management

CellAdvisor Summary Cell Site Optimization

R

F

Fibe

r LTE

LTE-

A

MB

MS

RFo

Fibe

r

Clou

d DAS

StrataSync




42 © 2016 Viavi Solutions Inc. www.viavisolutions.com 42 © 2016 Viavi Solutions Inc. www.viavisolutions.com 42 © 2016 Viavi Solutions Inc. www.viavisolutions.com www.viavisolutions.com www.viavisolutions.com www.viavisolutions.com







Best Practices of Interference Management- Sep 2016

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