antenna and basestation testing challenges - rohde & · pdf fileantenna and basestation...
TRANSCRIPT
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
36
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