Antenna and Basestation Testing Challenges Olaf Heisch Senior Director Target Account Management for Infrastructure Services
Antenna and
Basestation Testing Challenges
Olaf HeischSenior DirectorTarget Account Managementfor Infrastructure Services
Agenda in brief ….
� The Basestation and BTS evolution steps
� BTS Installation and Antenna Measurements
� PIM (Passive Intermodulation) Basestation Testing
� Over - the - Air Measurements
� IR (Interference Hunting ) Spectrum Clearance
� Questions & Answers
1992 – 2002
BTS in a Cabinet Solution
In consequence: HetNet architecture becomes reality and drives
several rollout projects, whether for indoor (DAS/Small Cell) or
Macro MSR-BTS scenarios
Mobile Networks
Field Service ProjectsRAN Expansion & Modernization & Swap
Increasing RAN site capacity by adding new equipment and SW
Small Cell BuildE2E solution, from planning to rollout as traffic increase
RAN BuildBuilding new RAN sites and/or networks incl. full site rollout
Multi Vendor RolloutRAN&Microwave project management in a shared environment
Fiber Network RolloutPlanning, designing & building E2E fiber networks
Mobile Networks
Field Service ProjectsPacket Transport Build & Expansion
Building & Upgrading IP/Optical/Microwave for RAN
Managed ServicesHotline Support & Site Security
Benchmarking & Drive TestingNetwork Verification against competition & Optimization
Interference HuntingDetection and suppression of non-wanted/non-allowed signals
Reporting FunctionsData Analysis and Data preparation for Management
Antennas
Tower Mounted Amplifier and/or RRH
RF/Fiber Cables
BTS / BBU
RF Cables
Performance of the Site
Radio Quality=
Service Quality
Connectors
Measurements are key for the service quality!
Site Installation is fundamental for Radio Networks
Three Step Site Measurement Concept
Antennas
Tower Mounted Amplifier and/or RRH
RF/Fiber Cables
BTS / BBU
RF Cables
Connectors
Antennas as most important component
ı Antennas are the most important component inany mobile network site.
ı An ideal transmit antenna converts all incomingconducted power into radiated power with nopower reflected back to the transmitter.
ı Antennas must be properly matched to theiroperational band for maximum efficiency.
ı Incorrectly installed or damaged antennas can havea severe performance impact.
ı Antennas must also be oriented properly in both azi muth and elevation for optimum coverage and efficiency.
ı Wind load, weather behavior (lightning protection) and aging changes Antenna efficiency.
ı Testing before installation is needed & result repo rting is required by MNO’s.
Why do we need Cable and Antenna Measurements today?
ı To ensure cable and antenna are properly installed before connecting to BTS
ı To ensure high quality of installed baseı To prevent push of responsibility due to
many contractors/vendors involve� Cable & antenna provider/installer� Base station vendors
ı Minimize later trouble shooting
ı 3 Sector Site to 6 Sector BTS incl. RET,4X4 MIMO, integrated TMA
Filter and amplifier measurements as of today
ı Filters often used on base stations to keep out other signals (band-pass-filter, duplexer, s.o.).
ı Amplifiers (such as TMAs) may be used in some cases as well.
ı Note that to test an amplifier, we may have to inje ct some kind of DC power (bias) in order to power up the device.
ı LNAs are sometimes used when making measurements as well.
What can go wrong ….. Antennas� Poor antenna isolation/matching� Loose connectors� Transport or weather damages
TMA and Ext. Components� Gain problems� Internal Filter problems� A&E handling problems
Cables� Poor or corroded cable connection� Poor isolation or ground� Damaged or broken cables� Unpaired or interchanged cables
Connectors� Improperly installed connectors� Weather (entrapped moisture) problems
Cable and Antenna Measurements, still needed …
Legacy / Installed BaseMacro BS BTS + RRH
1 Port measurementsı Feeder / Jumper Return Loss / VSWRı Distance to Fault (DTF)ı Antenna VSWRı Cable insertion loss
2 Port measurementsı Antenna decouplingı TMA gain test
Can bevery long and complex in an
In-Building-Solution
Antenna analysis example
ı Response is most commonly displayed as VSWR (voltage standing wave ratio)or magnitude.
ı For magnitude, we want the maximum return loss dB (most negative value).
ı For VSWR, we want a value as close to 1 (perfect match) as possible.
Distance to Fault example
ı Distance to fault measurement results can be provided graphically or in a table.
ı The parameters of interest are both the location of the fault (meters) and the magnitude of the returned signal (in dB).
ı A “fault” is usually defined by the magnitude of the reflection (e.g. connectors create lower level reflections than true faults).
Aligned Test Setup and Test Result Reporting
becomes time extensive factor � Wizard and Report GeneratorCentralized configuration
WIZARD guided measurements execution
Standardizedreporting
Aligned Test Setup and Test Results
R&S Mobile View 1.0 for Android is live, via google play store.
https://play.google.com/store/apps/developer?id=Rohde+%26+Schwarz+GmbH+%26+Co.+KG&hl=en
Aligned Test Setup and Test Results
R&S Mobile View 1.0 for Android is live, via google play store.
R&S Mobile View currently supports instrument series FSH, ZVH and FPH.
QualiPoc Android
Site Acceptance Reportı Site Acceptance appears on a separate monitor on
QualiPoc if option is licensed
ı Site Acceptance consists out of 3 parts:� Project : Contains project related information
� Sectors : Contains the sector technology and if cell locking shall be used, also channel and cell information
� Job : Select the job containing all the tests that shall run in order to check this site
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QualiPoc Android
Site Acceptance ReportJob – supported test typesThe following basic tests are available for site acceptance tests:ı Call to answering stationı Call to any number
ı FTP DL and ULı HTTP DL and UL
ı PING
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Measuring call setup time
Measuring data throughput
Measuring round trip time (RTT)
QualiPoc Android
Site Acceptance ReportSite Acceptance Report contains the following information:
ı Project informationı Measurement summaryı Results per sector ı Chart of recorded RF parameters
� LTE: SINR, RSRP, RSRQ� WCDMA: Aggr. Ec/Io, Aggr. RSCP� GSM: RxLev, C/I
ı KPI classification with all specified thresholds
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LTE/LTE-A Frequency Bands (FDD) and IntermodulationsE-UTRA
OperatingBand
Uplink (UL) operating band Downlink (DL) operating band
FUL_low – FUL_high [MHz] FDL_low – FDL_high [MHz]
1 1920 – 1980 2110 – 2170
2 1850 – 1910 1930 – 1990
3 1710 – 1785 1805 – 1880
4 1710 – 1755 2110 – 2155
5 824 – 849 869 – 894
6 830 – 840 875 – 885
7 2500 – 2570 2620 – 2690
8 880 – 915 925 – 960
9 1749.9 – 1784.9 1844.9 – 1879.9
10 1710 – 1770 2110 – 2170
11 1427.9 – 1447.9 1475.9 – 1495.9
12 699 – 716 729 – 746
13 777 – 787 746 – 756
14 788 – 798 758 – 768
17 704 – 716 734 – 746
E-UTRA Operating
Band
Uplink (UL) operating band Downlink (DL) operating band
FUL_low – FUL_high [MHz] FDL_low – FDL_high [MHz]
18 815 – 830 860 – 875
19 830 – 845 875 – 890
20 832 – 862 791 – 821
21 1447.9 – 1462.9 1495.9 – 1510.9
22 3410 – 3490 3510 – 3590
23 2000 – 2020 2180 – 2200
24 1626.5 – 1660.5 1525 – 1559
25 1850 – 1915 1930 – 1995
26 814 – 849 859 – 894
27 807 – 824 852 – 869
28 703 – 748 758 – 803
29 N/A 717 – 728
30 2305 – 2315 2350 – 2360
31 452.5 – 457.5 462.5 – 467.5
32 N/A 1452 – 1496
LTE/LTE-A Frequency Bands (TDD)
E-UTRA OperatingBand
Downlink (DL) / Uplink (UL) operating band
Flow – Fhigh [MHz]
33 1900 – 1920
34 2010 – 2025
35 1850 – 1910
36 1930 – 1990
37 1910 – 1930
38 2570 – 2620
39 1880 – 1920
40 2300 – 2400
41 2496 – 2690
42 3400 – 3600
43 3600 – 3800
44 703 - 803
Intermodulation Aspects from a BTS perspective
ı Linearity is Key – The Basestation itselfı Active Intermodulation due to PA’sı Intermodulation due to BTS RF Frontendı Intermodulation of Duplexer or Combiner
ı Passive Intermodulation ı Components along the site installationı Bias-Tee’s & Jumperı Lightning Protectionı Splitterı Add-On Filters
BTS PA & RF Frontend is driving factor for intermodulation in field
Pin
Pout 1dB Compression Point
1dB CP - 3dB � Powertage Working Point GMSK (GSM)
1dB CP - 6dB � 8 PSK (EDGE)
1dB CP - 9dB � WCDMA (QAM)
1dB CP - 10dB (min)
� OFDM (LTE, 256QAM � 30-35dB)
In case of less linearity…Co-Channel & Adjecent Channel Interference
Pin
Pout
Working pointLTE channel
f0
RF-Filter
f
PIM Uplink/Downlink
Source: “PIM Testing Best Practices White Paper”
It‘s all about Link-Budget….
Mobile-SensitivityBTS
TMA
UL Path-LossCable-Loss
TXoutDL Path-Loss
RX-Sensitivity
Mobile TXout
Examples Path Loss R=5Km:
900 MHz � 105dB
1800 MHz � 112dB
2100 MHz � 113dB
2600 MHZ � 115dB
3500 MHz � 117dB
Example Downlink:
TX_out (40Watt) � 46dBm
Cable_Loss � -3dB
Antenna_Gain � 12dB
DL_(900MHz/R=5Km) � -105dB
Diversity_Gain � 3dB
Signal to Noise Ratio � -9dB
_______________________________________
Mobile_RX_Level � -56dBm
Mobile_Sensitivity � -100dBm
________________________________________
System Margin DL � 44dB
needed for … Indoor coverageFading margin
Multipath conditions
S/N 3dB � GMSK (GSM)
S/N 6dB � 8 PSK (EDGE)
S/N 9dB � WCDMA (UMTS)
S/N 10dB (minimum)
� OFDM (LTE, 16QAM up to 256QAM)
BTS and PIM
Passive Intermodulation
PIM is probably an issue when:
• By increasing the output power of the BTS, the noise level in the receiver path increases significantly (factor of 3).
• For every dB more on the transmitted signal,the received signal increases by approx.. 3 dB
BTS affected by PIM
Interference
Noise level increases
Quality of Service reduced
Reduced coverage
Low data rates
Drop calls
No service at all
Lost revenue
$$$
Why are operators concerned regarding PIM and bad VSWR ???
Passive Intermodulation (PIM) Testing due to non-linear-componentsı Typically these are damaged or corroded base statio n components (the “rusty bolt”) but can be
generated by a wide variety of objects.
ı To test for PIM, a pair of signals with a given fre quency spacing is injected into the DUT. Intermodulation products will be generated at known frequencies if PIM is present.
ı In FDD networks multiple tones in the DL frequency range can generate interference in the UL band. � Receiver sensitivity goes down!
PIM symptoms
Performance issues reportedby the network:
ı Low signal to noise ratioı Noise floor increaseı Reduced data ratesı Dropped callsı Reduced coverage ı Non-accessibility
� No VSWR issues found by field teams
Source: R&S®NPA Network Problem Analyzer
What is a PIM Analyzer?
How to work out PIM issues? Cable&Antenna Tester + PIM AnalyzerModels Transmit (TX) Frequency MHz Receive (RX) Frequency MHz
700 732 – 766 698 – 722 (L)779.5 – 804.5 (U)
700A 758 – 803 703 – 748
800 791 – 821 832 – 862
850 869 – 894 824 – 849
900 925 – 960 876 – 915
Dual Band 1821 1805 – 1880 1710 – 17851920 – 1980
Dual Band 1921 1930 – 19902110 – 2155
1870 – 19101710 – 1755
2600 2620 – 2690 2500 – 2570
One-Port measurements for 2 X 40W Output Poweron battery operation needed:
• PIM measurements• Distance to PIM• Reporting functions (HTML&PDF)
Over-The-Air (OTA) Measurements for Outdoor & Indoor
Conducted vs. OTA measurements
Con
duct
ed
mea
sure
men
ts • Cable loss power• Distance to fault• Reflected power (VSWR, return loss)• Transmitted power• Insertion loss• Gain• Decoupling• Passive intermodulation
Ove
r th
e A
ir m
easu
rem
ents • Spectrum monitoring
• Interference hunting• Demodulation of pilot channels• DL resource block allocation• MIMO measurements• Carrier agregation measurements• Functional testing
R&S®ZVH R&S®FSHR&S®FPH R&S®PR100 QualiPoc Android R&S®TSMA
April 2017Antenna and base station testing challenges
PiMPro Tower
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R&S®ZPH
Over-The-Air (OTA) MeasurementStandard Spectrum Measurements
ı Spectrum emission mask
ı Occupied Bandwidth
ı Spurious emissions
ı Power on pulsed signals (TDMA-Power)
ı Harmonic distortion
ı ACLR
ı AM modulation depth
ı Channel Power
Over-The-Air (OTA) MeasurementRF Measurements - LTE
ı Measurement of:ı Constellation diagramı BTS Scannerı Resources allocation
Over-The-Air (OTA) MeasurementRF Measurements - LTE (Carrier Aggregation/MIMO)
ı For LTE FDD / LTE TDD ı Measures 2 or 3 carriers over the air (OTA)ı User is setting Frequency and Bandwidthı Main RF parameters displayed ı Pass indication is displayed if Cell ID is same ı Antenna values are greyed out if results are out
of range (one of the antennas is not received)
ı Application: quick check whether the CA feature is working OK during base station installation and maintenance
Network Scanning Tools
ı Non-intrusive passive Scannersı Subscribed UEs / Mobiles
� Combination is best
What about…ı Detection of crossed feeders, broken feeders…ı System internal interference optimization (pilot pollution)ı Uplink / Downlink interference detection (Spectrum measurement)ı Decoding of BCH information (missing neighbors, configuration issues)ı Coverageı ……
Scanner example: Automatic Channel Detection
Multi-Band andMulti-Technology
Networks
Network overview
GSM, UMTS, LTE, CDMA/EV-DO, TETRA, WIMAX
Spectrum � Interference Hunting & Clearance
Interferences – almost everything is possible
Interference Hunting
ı Interference hunting is the process of identifying and locating sources of interference.
ı Analysis of the signal can provide important clues as to its origin / location.
ı In almost all cases, radiolocation(direction finding) will be necessaryto establish the physical locationof the source.
Steps in Interference Huntingı Stage 1 : Identify general areaı What cells / sectors are being affected?ı Area usually < 10 km radius
ı Other systems involved to 1st step very often
ı Stage 2 : Driving aroundı Vehicle mounted antenna or direction-finding systemı Try to get within ~ 100 m radius
ı Frequency identified and demodulated
ı Stage 3 : Walking aroundı Last few hundred meters/ sweep devicesı Areas of interest / Hand-held directional antennas
ı Access to objects needed ☺
Tools for Interference Hunting
ı Handheld instruments fall into two categories
ı Monitoring receivers : FFT-basedı Spectrum analyzers : Swept / heterodyne-based
ı Dedicated direction-finding systems can be useful in a number of cases
ı Antennas (vehicle and handheld)
ı Accessories (Filters, LNAs, etc.)
Monitoring Receivers vs. Spectrum Analyzers
ı Speed crucial in interference huntingı Monitoring Receivers : FFT-based processing� very, very fast
ı Spectrum Analyzers : use swept / heterodyne architecture : very configurable, but slower
ı Generally speaking, monitoring receivers are superior for interference hunting due to speed and sensitivity
ı Spectrum analyzers provide good performance and additional non-IH measurement capabilities(e.g. for decoding acc. 3GPP)
Direction findingı Automatic direction finding systems can
determine the likely location of a signal source using one or more DF methodologies (integrated real time algorithm)
ı Systems normally consist of a DF receiver, special-designed antenna, and control / processing SW.
ı Very helpful in locating short-duration interferers or distant interferers.
ı Good multipath resistance also allows use in urban environments.
Direction finding
Thank you