08_U-LI 201 Spectrum Test and Instructions for YBT250-20080613-A-1.0_level 1

HUAWEI TECHNOLOGIES CO., LTD.

Huawei Confidential

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www.huawei.com

Spectrum Test and Instructions for YBT250

ISSUE1.0

Page 2HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

The WCDMA system is a restricted communication system by the interference. The network quality, capacity and coverage are all related to the background noise.

When design the radio network, we must obtain the strength of the background noise in the coverage area.

If strong interference exists within the band, spectrum test need to be performed, or the operator have to apply for new frequency spectrum.


After studying this course, you should be

able to:

Know the sources of electromagnetic

background interference.

Master the methods for electromagnetic

background test.

Know how to use YBT250 for spectrum

test.


Chapter 1 Impact of Electromagnetic Interference on the System

Chapter 2 Sources of Electromagnetic Background Interference

Chapter 3 Introduction to Interference Test Tools

Chapter 4 Methods for Electromagnetic Background Test

Chapter 5 Instructions for YBT250



1.1 Bands Used in the WCDMA System

1.2 Interference Requirements for UE Reception

1.3 Interference Requirements for NodeB Reception


Bands used in the WCDMA system

Operating Band

UpLink BandUE transmit, Node B

receive

DownLink BandUE receive, Node B

transmit

I 1920 - 1980 MHz 2110 -2170 MHz

II 1850 -1910 MHz 1930 -1990 MHz

III 1710-1785 MHz 1805-1880 MHz

IV 1710-1755 MHz 2110-2155 MHz

V 824 - 849MHz 869-894MHz

VI 830-840 MHz 875-885 MHz

VII 2500 - 2570 MHz 2620 - 2690 MHz

VIII 880 - 915 MHz 925 - 960 MHz

IX 1749.9 - 1784.9 MHz 1844.9 - 1879.9 MHz

Band I, II, V and VII are most popular used in the world.

Band I is used in China.


Impact of Electromagnetic Interference on the System Determine the impact of interference on the system according to experience, as

shown in the following table (for UE).

Interference Band

Interference Level Not Affecting

Receiver Sensitivity (With the Sensitivity Worsened by 0.1 dB)

Acceptable Interference Level

(With the Sensitivity Worsened by 3 dB)


(With the Sensitivity Worsened by 6 dB)

Interference That Seriously Effects Equipment Indexes

Instead of Equipment Running, Lower Than the Maximum Signal Strength (-25 dBm) the UE Can

Receive by 10 dB

Protocol Requirement

2110-2170 MHz (co-frequency interference)

-117 dBm/ 3.84 MHz-101 dBm/ 3.84 MHz

-96 dBm/ 3.84 MHz -35 dBm/ 3.84 MHzThe required sensitivity is -107 dBm/ 3.84 MHz.

2095-2185 MHz (adjacent channel interference, deviated from the carrier by 5 MHz)

-82 dBm/ 3.84 MHz -66 dBm/ 3.84 MHz -61 dBm/ 3.84 MHz -16 dBm/ 3.84 MHz

-66 dBm/ 3.84 MHz (with the sensitivity worsened by 3 dB)

2095-2185 MHz (in-band blocking, deviated from the carrier by 10 MHz)

-72 dBm/ 3.84 MHz -56 dBm/ 3.84 MHz -51 dBm/ 3.84 MHz -6 dBm/ 3.84 MHz


2095-2185 MHz (in-band blocking, deviated from the carrier by 15 MHz)

-60 dBm/ 3.84 MHz -44 dBm/ 3.84 MHz -39 dBm/ 3.84 MHz 6 dBm/ 3.84 MHz


Other bands (out-of-band blocking and spurious response)

-60 dBm/ 3.84 MHz -44 dBm/ 3.84 MHz -39 dBm/ 3.84 MHz 6 dBm/ 3.84 MHz


Note: dBm/Hz refers to the level unit of single-tone signals. The reference port for measurement is the reception port of the UE antenna. The reference requirements are based on the protocol TSG25.101.


Impact of Electromagnetic Interference on the System Determine the impact of interference on the system according to experience,

as shown in the following table (for NodeB).

Interference Band

Interference Level Not Affecting

Receiver Sensitivity (With the Sensitivity Worsened by 0.1 dB)


(With the Sensitivity

Worsened by 3 dB)


(With the Sensitivity

Worsened by 6 dB)

Interference That Seriously Effects Equipment Indexes

Instead of Equipment Running, Lower Than the Maximum

Signal Strength (-70 dBm) the UE Can Receive by 10 dB

Specification for NodeB Indexes

1920-1980 MHz (co-frequency interference)

-121 dBm/ 3.84 MHz -105 dBm/ 3.84 MHz-100 dBm/ 3.84 MHz

-80 dBm/ 3.8 4MHzThe sensitivity specification is -123 dBm/3.84MHz.

1900-2000 MHz (adjacent channel interference, deviated from the carrier by 5 MHz)

-63 dBm/ 3.84 MHz -47 dBm/ 3.84 MHz -42 dBm/ 3.84 MHz -22 dBm/ 3.84 MHz-42 dBm/ 3.84 MHz (with the sensitivity worsened by 6 dB)

1900-2000 MHz (in-band blocking)


1900-2000 MHz (out-of-band blocking)


935-960 MHz1805-1880 MHz (out-of-band blocking)

-5 dBm/Hz 11 dBm/Hz 16 dBm/Hz 36 dBm/Hz16 dBm/Hz (with the sensitivity worsened by 6 dB)

Other bands (out-of-band blocking)

-26 dBm/Hz -10 dBm/Hz -5 dBm/Hz 15 dBm/Hz-5 dBm/Hz (with the sensitivity worsened by 6 dB)

Note: dBm/Hz refers to the level unit of single-tone signals. The reference port for measurement is the reception port of the NodeB antenna. The reference requirements are based on the protocol TSG25.101. During analysis, the index for adjacent channel interference and in-band blocking is 10 dB better than that specified in the protocol. This is the RF index the NodeB

can ensure.


Impact of Electromagnetic Interference on the System

Interference requirements for UE reception (taking the band 2110 - 2170 MHz as an example) Interference band: 2110 - 2170 MHz

Interference level not affecting receiver sensitivity: -117 dBm/3.84 MHz, with the sensitivity worsened by 0.1 dB

Acceptable interference: -101 dBm/3.84 MHz, with the sensitivity worsened by 3 dB

Acceptable interference: -96 dBm/3.84 MHz, with the sensitivity worsened by 6 dB

Interference that seriously effects equipment indexes instead of equipment running:

-35dBm/3.84MHz, lower than the maximum signal strength (-25 dBm) the UE can receive by 10 dB

Sensitivity: at least -107 dBm/3.84 MHz as required in the protocol


Impact of Electromagnetic Interference on the System

Interference requirements for NodeB reception (taking the band 1920 -1980 MHz as example) Interference band: 1920 - 1980 MHz

Interference level not affecting receiver sensitivity: -121 dBm/3.84 MHz, with the sensitivity worsened by 0.1 dB

Acceptable interference: - 105 dBm/3.84 MHz, with the sensitivity worsened by 3 dB

Acceptable interference: - 100 dBm/3.84 MHz, with the sensitivity worsened by 6 dB

Interference that seriously effects equipment indexes instead of equipment running: -80 dBm/3.84MHz

Sensitivity: at least -123 dBm/3.84 MHz as required in the protocol









2.1 2G Band Allocation

2.2 Analysis on Interference Sources


2G Band Allocation

In china, 2G bands are allocated as follows:

Band (MHz) Occupation

1710~1720/1805~1815 GSM1800 for China Mobile

1745~1755/1840~1850 GSM1800 for China Unicom

1800~1805 SCDMA (Beijing Xinwei)

1850~1865/1920~1945 Reserved

1865~1880/1954~1960 PCS1900 (not occupied)

1880~1900/1960~1980 FDD WIL (used by China Telecom and China Unicom in some cities by the end of 2002)

1900~1920 TDD WLL (PHS/DECT)

Planning of Bands 1.8 GHz and 1.9 GHz in China


Chapter 2 Sources of Electromagnetic Background

Interference

2.1 2G Band Allocation

2.2 Analysis on Interference Sources

− TDD WLL

− FDD WLL

− Microwave transmission

− Repeater


Analysis of Interference Sources

TDD WLL (PHS/DECT)

The system occupies the 1900 -1920 MHz band.

For the PHS system, the bandwidth occupied by the channel is

smaller than or equal to 288 KHz.

For the DECT system, the bandwidth occupied by the channel

is smaller than or equal to 1533 KHz.

FDD WLL

Uplink band: 1880 -1900 MHz

Downlink band: 1960 -1980 MHz

The bandwidth occupied by the system is 1.25 MHz.

The EiRP of a typical NodeB is about 25 dBm.


Analysis of Interference Sources

Microwave transmission Occupied bandwidth: usually over several MHz.

Normal reception level of microwave is about -60 dBm, imposing a great impact on the WCDMA system.

Repeater Nonstandard installation results in insufficient antenna isolation, thus self-

excitation. This affects normal running of the NodeB where the repeater is installed.

The repeater is a wide-band non-linear amplifier. Its intermodulation index exceeds the one specified in the protocol. The repeater easily causes

interference to nearby NodeBs when its power is too large.

Others Some communication devices occupy WCDM bands. Unreasonable installation

and isolation result in high harmonic signals and thus cause interference to the WCDMA system. In addition, radar is also a common interference source.









1.1 Spectrum Analyzer

1.2 Antenna

1.3 Low Noise Amplifier


Interference Test Tools

Spectrum analyzer

A spectrum analyzer is used to test frequency domain features of signals, covering spectrum, adjacent channel power, fast time domain scanning, spurious radiation and intermodulation attenuation.

Key indexes

− Resolution bandwidth (RBW)

− Input frequency and central frequency (F0)

− Sensitivity

− Span

− Reference level (RefLvl)

− Video filter bandwidth (VBW)

− Input signal attenuation (ATT)

− Detection mode (RMS)

− Sweep time



Main technical indexes of various spectrum analyzers

Model Working Band Sensitivity (1 Hz)Minimum Resolution

Bandwidth

HP8591E 30 - 1.8 GHz -145 dBm 30 Hz

HP8594E 30 - 2.9 GHz -142 dBm 30 Hz

HP8595E 30 - 6.5 GHz -142 dBm 30 Hz

HP8561E 30 - 6.5 GHz -145 dBm 1 Hz

YBT250 30 - 2500 MHz -132 dBm 1 KHz



Antenna

Omnidirectional antenna: It facilitates interference

measurement instead of interference location.

Directional antenna: It is used to search interference sources.

The more distinct the directivity is and the higher the gain is,

the stronger the searching capability is.

Common directional antennas:

− Panel antenna

− Yagi antenna

− Log periodic antenna



Low noise amplifier (LNA)

Used to improve the receiver sensitivity of the testing instrument.

During a test, we can select the LNA with 30 dB gain and 5 dB

noise coefficient.

Additional power supply needs to be considered for the LNA. Some

testing instruments (like YBT250 ) are configured a built-in LNA.

For a cascade network, the noise coefficient of the system depends

on level-1 noise coefficient when a high gain amplifier is configured

at the front end of the system.









4.1 Preparations

4.2 Setting Basic Parameters

4.3 Measurement Procedure

4.4 Data Processing


Preparations Master local radio band planning and the usage of radio

equipment by enterprises

For pilot networks

− No available frequency is determined and the testing frequency is allocated

temporarily. During a spectrum test, you need to scan the entire band or

select several 5 MHz bands for test according to the local frequency

resources for use at the later phase.

For commercial networks

− Frequency resources are determined. The test focuses on the bands used

by the operator and is intended to eliminate interference at the bands in

use.


Preparations

Determine the test time and place

Uplink electromagnetic interference test

− Test place: the place where the NodeB antenna is installed.

− Conduct the test in three directions (0˚, 120˚ and 240˚).

− Use a portable antenna or the NodeB’s antenna.

Downlink electromagnetic interference test

− Select a certain quantity of typical points within the cell coverage for test.

− Conduct the test in three directions (0˚, 120˚ and 240˚).

− Use a portable antenna.

− Perform a drive test, drive the vehicle slowly along the main streets covered by a

cell and then stop the vehicle for further test when detecting the interference.


Preparations

Prepare tools and make sure

that they are available:

Spectrum analyzer

GPS receiver

Compass

Testing antenna

Vehicle


Preparations

Prepare tools and make them available:

Connect an LNA to the spectrum

analyzer with low receiver sensitivity.

During system connection, check

whether connectors are matched and

ensure continuous power supply for

the instruments.

Device Connector Model

Yagi antenna N (female)

Bandpass filter N (female)

YBT250 spectrum analyzer

N (female)

LNA SMA (male)

Feeder N (male)

Feeder N (male)/SMA (male)

50 ohm matched load

N (male)


Yaqi antenna

Filter

LNA

Cable


Chapter 4 Methods for Electromagnetic Background

Test

4.1 Preparations



4.4 Data Processing


Setting Basic Parameters

Set the following basic parameters

Parameter Parameter Value Remarks

FoUplink: Fo=1950; downlink: Fo=2140

(MHz)

Central frequency of the

spectrum under test

SPAN For example, SPAN=100 MHzSpan of the testable

spectrum

MaxHold

/Average

Select MaxHold or Average according to occurrent or continuous interference respectively.

Display the maximum value/the average value

RefLvl

Do not select AutoLevel. Set the reference level according to the testing signal and try to display the signal in the middle of the spectrum analyzer.

Reference level

Vertical Scale

10 dB/div (default) Vertical scale



Test

4.1 Preparations



4.4 Data Processing


Measurement Procedure

Determining the test azimuth

Select the position where the NodeB antenna is installed for test. Usually, you

need to conduct the test in three directions. If the direction of the NodeB

antenna is determined, make the testing antenna be in the same direction as

the NodeB antenna.

Searching interference

Search interference within the uplink band and then within the downlink band.

Specific operations:

− Enter the YBT250 spectrum test interface and set Fo and Span.

− Fill in the record table, save data files, and check whether there is interference.

Judge rule: whether there is interference waveform higher than the noise floor.


Measurement Procedure Interference confirmation

During interference search, if there is interference, conduct a interference confirmation test. Specific steps are as follows:

− Enter the interface for measuring YBT250 NodeB test information, and set Fo to a central frequency point near interference, Span to 3 × interference bandwidth, and Channel Bandwidth to 4 M.

− Read the in-band interference power, fill in the record table, and save the data file.

In-band test

For the customer pilot, test the in-band power for all the candidate channels. For commercial offices, focus on testing the in-band power for the available channels. Specific steps are as follows:

− Enter the interface for measuring YBT250 NodeB test information, and set Fo to a central frequency point of the testing channel, Channel Bandwidth to 5 M, and Span to 3 × interference bandwidth.

− Read the in-band power, fill in the record table, and save the data file.


Measurement Procedure

Downlink drive test

Downlink drive test means driving a vehicle slowly along the main streets covered by a cell and conducting a point test after discovering large interference.


− Enter the YBT250 spectrum test interface.

− Set Fo to 2140 MHz and Span to 60 MHz. Search interference when the vehicle moves at a speed lower than 15 km/h.

Point test items include:

− Set Fo to a central frequency point near the interference, Channel Bandwidth to 4 MHz, and Span to 3× interference bandwidth. Record the in-band interference power.

− Or set Fo to a central frequency point of the testing channel, Channel Bandwidth to 5 MHz, and Span to 3× channel bandwidth. Record the in-band power.



Test

4.1 Preparations



4.4 Data Processing


Data Processing

After completing measurement, perform data

processing.

After completing measurement for the test area,

output

WCDMA Electromagnetic Interference Test Form

After completing measurement for the entire

local network, output

Report on WCDMA Electromagnetic Interference

Test


Question

Is the interference level obtained

from the electromagnetic

interference test equal to the

level of the interference signals at

the top of the NodeB or at the

antenna port of the MS?


Answer

The testing system and WCDMA

system adopt different antennas

and feeders. Therefore, you

need to calculate the level of the

interference signals at the top of

the NodeB or at the antenna port

of the MS according to the test

data during analysis.


Answer

Testing system

Antenna gain: 3 dBi

Feeder loss: 1 dB

Measured interference level: -90 dBm

WCDMA system

Gain of the NodeB antenna: 10 dBi

Feeder loss: 2 dB

Interference level at the NodeB: 90 - (3 -1) + (10 - 2) ＝ -84 dBm


Question

How to estimate the power of the

interference level within the

channel bandwidth according to

the interference level within the

RBW?


Answer

The WCDMA system is a broadband system.

Therefore, you need to calculate the integral

power of the interference level within the

channel bandwidth.

RBW of the testing system: 10 KHz

Interference level within the RBW: -80 dBm

Channel bandwidth: 3.84 MHz

Integral power within the channel:

P = -80 + 10LOG(3.84*106/10*103) = -54dBm








Chapter 5 Chapter 5 Instructions for YBT250Instructions for YBT250

System connection

Power-on

Measurement

Measurement setting

Measurement result


Instructions for YBT250

Before site survey, you need to conduct a spectrum test

and find proper frequency test instruments.

Tektronix YBT250 is recommended.

Features of YBT250

Portable, easy to carry

System integration, with a built-in LNA



System connection

The matched antenna of YBT250 is Yagi

directional antenna.

A portable small antenna can be used for

electromagnetic background test.

YBT250 can use the battery delivered

together or can be externally connected to

the power supply.

Power-on

Press Power and enter the Windows CE

operating system.

Enter the measurement interface through

the touch screen of YBT250.


Yaqi antenna

Filter

LNA

Cable



Measurement

YBT250 supports the following three

measurement functions:

− NodeB information measurement

− Spectrum test

− Interference source search

Spectrum test supports the following two

display modes:

− Spectrum mode

− Spectrogrum mode



Measurement

The spectrum mode is used for real-time measurement.

− Determine the band to be tested and set Fo.

− Modify the span.

− Observe the spectrum diagram, adjust the Fo and span, and view whether there is

interference.

− The Trace menu includes the following options:

▪ Normal, Max Hold, Min Hold and Max/Min Hold

− Save the current spectrum diagram.

Note: You need to set RefLvl correctly to make the measured signal level

range from RefLvl to (RefLvl-70dB). The difference of the maximum level and

minimum of level that the YBT250 can correctly display is 70 dB.



Measurement

The spectrogrum mode is used to check whether there is interference at a certain band in a specified time. The horizontal axis stands for the band and the vertical axis for the time.


− Set the automatic storage option and a file name.

− Set the band (Fo and span).

− Open the saved file and view interference.

To view the exact interference, you can export the file as:

− A picture

− Data (.txt,.csv)

− Export the data from YBT250 using the U disk or network cable.



Measurement setting

− Fo: the central frequency of the testing signal (unit: MHz)

− Span: It can be set to 100 MHz, 10 MHz or 5 MHz.

− RBW: It is automatically set by the instrument according to the span.

− MaxHold/Average: display the maximum value and the average value.

− RefLvl: set according to the interference level.

Measurement result

WCDMA Electromagnetic Interference Test Form and Report on WCDMA

Electromagnetic Interference Test




Conclusion

This course describes possible

interference sources at the WCDMA

band, methods for electromagnetic

background test, and instructions for

YBT250.

Thank You!www.huawei.com

Documents

08_U-LI 201 Spectrum Test and Instructions for YBT250-20080613-A-1.0_level 1