wcdma interference processing guide - huawei

W-Interference Processing Guide-20060330-A-3.0 For internal use only

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WCDMA RNP For internal use only

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3.0

W-Interference Processing Guide

(For internal use only)

Prepared by Li Junwei and Jiang Lihong Date 2006-03-03

Reviewed by Xie Zhibin, Li Wenhui, Hu Wensu, Qin Yan, Gong Haitao, Wan Liang, Yu Yongxian, and Hu Mingchao

Date

2006-03-16

Reviewed by Qin Yan and Wang Chungui Date 2006-03-23

Approved by Date

Huawei Technologies Co., Ltd. All Rights Reserved



Revision Records

Date Revised version

Description Author

2006-03-03 3.00 Initial transmittal Li Junwei and Jiang Lihong

2006-03-15 3.01 Revising it according to the first review Li Junwei and Jiang Lihong

2006-03-22 3.02

Modifying flow chats, adding acronyms and format, adding introductions to each chapter, modifying judgment criteria for internal and external interference, modifying cases, removing operators' information, adding figures to locating methods, and explaining the typical RTWP

Li Junwei and Jiang Lihong



Table of Contents

Chapter 1 Introduction to Interference Processing ....................................................................... 9

Chapter 2 Interference Processing Procedures .......................................................................... 10

Chapter 3 Methods for Finding Interferences .............................................................................. 11 3.1 Finding Interferences by Network Operation Indexes ......................................................... 11 3.2 Sorting Candidate Cells by Priority ...................................................................................... 11

Chapter 4 Interferences Analysis and Location........................................................................... 12 4.1 Collecting data and Confirming Interferences ..................................................................... 12

4.1.1 Obtaining Interference Data ...................................................................................... 12 4.1.2 Confirming Interferences .......................................................................................... 12 4.1.3 Customizing Judgment Criteria for Abnormal Interferences ..................................... 14

4.2 Judging Types of Interferences ........................................................................................... 14 4.2.1 Criteria for Judging Interferences ............................................................................. 14 4.2.2 Sampling RTWP Variation Due to Internal Interference ........................................... 15 4.2.3 Sampling RTWP Variation Due to External Interference .......................................... 18

4.3 Equipment and Documents Needed In Interference Test ................................................... 29 4.4 Locating Internal Interference .............................................................................................. 30

4.4.1 Initial Location ........................................................................................................... 30 4.4.2 On-site Location ........................................................................................................ 31

4.5 Locating External Interference ............................................................................................ 32 4.5.1 Preparations before On-site Location ....................................................................... 32

Chapter 5 Interference Elimination ............................................................................................... 35

Chapter 6 Interference-related Cases ........................................................................................... 36 6.1 A Intermodulation Interference Case ................................................................................... 36 6.2 Repeater Interference Case 1 ............................................................................................. 36 6.3 Repeater Interference Case 2 ............................................................................................. 36 6.4 Repeater Interference Case 3 ............................................................................................. 36 6.5 Interference Location Cases in Indoor Distributed System ................................................. 36 6.6 PHS-to-WCDMA Interference Location Cases ................................................................... 36

Chapter 7 Introduction to Locating Downlink Interferences ...................................................... 37 7.1 Locating Downlink Interference ........................................................................................... 37 7.2 Analyzing Downlink Interference ......................................................................................... 37 7.3 Eliminating Downlink Interference ....................................................................................... 37 7.4 Downlink Interference Cases .............................................................................................. 37

Chapter 8 Appendix 1: Basic Knowledge about Interference .................................................... 38 8.1 Definition of Interference ..................................................................................................... 38 8.2 Interference Influence .......................................................................................................... 38

8.2.1 Influence on Sensitivity ............................................................................................. 38 8.2.2 Influence on Algorithm .............................................................................................. 38 8.2.3 Influence on System ................................................................................................. 38

8.3 The source and features of Interference ............................................................................. 38 8.3.1 Internal Interference .................................................................................................. 38 8.3.2 External Interference................................................................................................. 39

8.4 PIM Description ................................................................................................................... 44 8.4.1 Connection of DIN connectors .................................................................................. 45 8.4.2 Occurrence of Antenna PIM ...................................................................................... 45 8.4.3 Controlling Antenna PIM ........................................................................................... 45 8.4.4 Features of Antenna PIM .......................................................................................... 46 8.4.5 Relationship between PIM and NodeB Alarms ......................................................... 46

Chapter 9 Appendix 2: RTWP Description ................................................................................... 47 9.1 RTWP Definition .................................................................................................................. 47 9.2 Uplink RF Channel Adjustment Principles........................................................................... 48



9.3 RTWP Error and Accuracy .................................................................................................. 49 9.4 RTWP Effect ........................................................................................................................ 50

List of Reference ............................................................................................................................. 51



List of Tables

Table 3-1 Sample list of network operation indexes ........................................................................ 11

Table 4-1 Equipment and Documents ............................................................................................. 29

Table 8-1 Technical parameters of PHS system .............................................................................. 39

Table 9-1 Received total wide band power(TS 25.215 v600) .......................................................... 47

Table 9-2 Absolute accuracy requirement ....................................................................................... 49

Table 9-3 Relative accuracy requirement ........................................................................................ 49

Table 9-4 Received total wideband power measurement report mapping ...................................... 49



List of Figures

Figure 2-1 Interference processing flow chat .................................................................................. 10

Figure 4-1 Analyzing interference in Nastar..................................................................................... 13

Figure 4-2 Configuring judgment criteria for abnormal interference in Nastar ................................ 14

Figure 4-3 Variation of RTWP due to load ....................................................................................... 16

Figure 4-4 Variation of RTWP due to improper connection of multiple RF ...................................... 16

Figure 4-5 Antenna-feeder structure ................................................................................................ 17

Figure 4-6 Variation of RTWP .......................................................................................................... 17

Figure 4-7 Variation of RTWP due to interaction of 2G and 3G signals .......................................... 18

Figure 4-8 Site distribution around the site 501800 ......................................................................... 19

Figure 4-9 Variation of RTWP in adjacent cells (1) .......................................................................... 19

Figure 4-10 Variation of RTWP in adjacent cells (2) ........................................................................ 20





Figure 4-15 Variation of RTWP ........................................................................................................ 22

Figure 4-16 RTWP variation of cell 45680 ....................................................................................... 22

Figure 4-17 Antenna location ........................................................................................................... 23

Figure 4-18 RTWP variation ............................................................................................................. 23

Figure 4-19 Site location .................................................................................................................. 24

Figure 4-20 RTWP variation of a NodeB near railway ..................................................................... 24

Figure 4-21 RTWP variation due to indoor air-conditioner ............................................................... 24

Figure 4-22 RTWP variation due to power on or off of outdoor air-conditioner of other operator.... 25

Figure 4-23 RTWP variation due to power on or off of indoor emergency lights ............................. 25

Figure 4-24 Long-time RTWP variation ............................................................................................ 26

Figure 4-25 Short-time RTWP variation ........................................................................................... 26

Figure 4-26 Frequency spectrum when the directional antenna approaches the YBT250 .............. 27

Figure 4-27 Uplink interference due to transmission line (1) ........................................................... 27

Figure 4-28 Uplink interference due to transmission line (2) ........................................................... 27

Figure 4-29 Long-time RTWP variation of the interference like self-excitation ................................ 28

Figure 4-30 Short-time RTWP variation of the interference like self-excitation ............................... 28

Figure 4-31 Frequency spectrum feature ......................................................................................... 28

Figure 4-32 Structure of interference test ........................................................................................ 29



Figure 4-33 RTWP variation when the diversity reception is not configured ................................... 31

Figure 4-34 Locating interference source by using AOA ................................................................. 33

Figure 4-35 Schematic drawing of middle location .......................................................................... 34

Figure 4-36 Schematic drawing of two-point location ...................................................................... 34

Figure 8-1 Frame structure of PHS system ..................................................................................... 39

Figure 9-1 Structure of uplink Rx channel of V1.3 NodeB ............................................................... 47



W-Interference Processing Guide

Key words: WCDMA, interference, main, diversity, RTWP, and intermodulation

Abstract: this document discusses the processing methods and process

Acronyms and abbreviations:

Acronym and Abbreviations Full spelling

PIM Passive Interactive modulation

RTWP Received Total Wideband Power

BCCH Broadcasting Channel

FNE Fixed Network Element

AOA Angle of Arrival



Chapter 1 Introduction to Interference Processing

This document aims to satisfy on-site engineers with the request from locating uplink interferences in WCDMA networks and provides common methods and operation process for locating uplink interference in WCDMA networks.

This document consists of the following chapters and content:

1) Chapter 1 Introduction to Interference Processing 2) Chapter 2 Interference Processing Procedures 3) Chapter 3 Methods for Finding Interferences 4) Chapter 4 Interferences Analysis and Location 5) Chapter 5 Interference Elimination 6) Chapter 6 Interference-related Cases 7) Chapter 7 Introduction to Locating Downlink Interferences 8) Chapter 8 Appendix



Chapter 2 Interference Processing Procedures

This chapter provides interference processing procedures, which are detailed in the following chapters

Figure 2-1 Interference processing flow chat



Chapter 3 Methods for Finding Interferences

You can find uplink interferences in WCDMA networks by several methods, but a common method is analyzing indexes related to network operation.

3.1 Finding Interferences by Network Operation Indexes

The best method for finding uplink interferences is observing the average RTWP among network operation indexes. Normally the unloaded network RTWP is about –105.5 dBm.

If the average RTWP of some cells reaches about –95 dBm, 10 dB higher than that of unloaded network, the cells encounters uplink interferences.

If the average RTWP of some cells reaches about –85 dBm, 20 dB higher than that of unloaded network, the cells encounters strong uplink interferences.

If conditions permit, solve the interference problem at once.

The maximum RTWP is recommend as a reference for judgment only, because it might be caused by an access peak or even is related to UE algorithm and performance. Therefore, you need not pay special attention to it.

Table 3-1 lists network operation indexes.

Table 3-1 Sample list of network operation indexes

RNCId CellId CellName Time(As hour)

VS.MaxRTWP VS.MeanRTWP

VS.MinRTWP

2 40661 NpCetr_ADE

2006-2-17 17:00

–52.5 –104.36 –105.3

1 48602 TaiHongBldg_CD

2006-2-17 17:00

–57.5 –94.89 –96.4

1 58143 KwongYu_CD

2006-2-15 16:00

–60.3 –82.79 –88.8

Indexes in Table 3-1 are from a network. The three cells are three typical types of cells.

The average RTWP of cell 40661 is –104.36 dBm, needless of attention. The average RTWP of cell 48602 reaches –94.89 dBm, so you must pay attention

to the cell. The average RTWP of cell 58143 reaches –82.79 dBm, the cell strongly interfered,

so you must pay special attention to the cell.

3.2 Sorting Candidate Cells by Priority

After selecting candidate cells according to average RTWP, sort candidate cells by priority according to the following factors:

Whether VIP subscribers are in the cell The cell traffic How important the cell is to KPIs of entire network

After considering these factors, process candidate cells by priority.



Chapter 4 Interferences Analysis and Location

4.1 Collecting data and Confirming Interferences

Locating interference problems is complex, so you must collect comprehensive data before location. This is key to solving interference problems. Without comprehensive data, locating problems on site or drawing a conclusion takes a longer time and is less efficient. Uplink interferences feature differently in different periods of a day or week, so tracing more RTWP contributes more to locating uplink interferences. To confirm interference, and determine the interference strength and types of consequent interference, you must collect the following data:

The RTWP data for 7 (days, at least 3 days) x 24 (hours) of cells to be located The RTWP data for 7 (days, at least 3 days) x 24 (hours) of cells adjacent to the cell

to be located

4.1.1 Obtaining Interference Data

Obtaining interference data proceeds as below:

1) Create cell routine test and then start it 2) Start the FTP Server for the target computer 3) Execute the following commands on the MML Command interface on M2000 Client:

ULD FILE: DSTF=”c:/bin/RtwpLog_NodeBxxx”, FLAG=RTWPLOG, IP=”10.161.209.251”, USR=”FTP authorized user name”, PWD=”FTP password”, CF=UNCOMPRESSED[,SD=2005&11&16, ST=15&30&50, ED=2005&11&16, ET=15&40&50] After the previous operations, the file is saved in the name of RtwpLog_NodeBxxx in the directory c:/bin.

4) Start Nastar, and select to import RTWP file to new project in import interface.

Note:

The IP in the previous MML commands is the IP of a NodeB.

4.1.2 Confirming Interferences

Confirming interference proceeds as below:

1) Start Nastar 2) Double click object tree function node 3) Select WCDMA Interference Analysis > Abnormal Interference Analysis

Select the cell to be analyzed. Wait for a time for analysis, and then the system displays an interface as shown in Figure 4-1.



Figure 4-1 Analyzing interference in Nastar

As shown in Figure 4-1, the cells are ranked according to interference strong to weak. In the column Interference, Nice indicates no interference Acceptable indicates the interference is acceptable Problematic indicates interference is present in the cell In the column Priority, H indicates you must pay attention to the cell by preference L indicates an cell with ordinary interference In the column BaseNoise, Nice indicates a normal base noise TBD (to be determined) indicates an abnormal noise figure, so you must pay

attention to the cell

4) Click in the tool bar, click a column, the system displays the interference chat and uplink CE chat In the chat, CE Resource Utilize reflects the usage of uplink credit (you can transfer it to

CE when it is divided by 2)



MainDivCurve reflects the RTWP of current main

4.1.3 Customizing Judgment Criteria for Abnormal Interferences

Customizing judgment criteria for abnormal interferences proceeds as below:

1) Start Nastar 2) Double click object tree function node 3) Double click WCDMA Interference Analysis 4) Select Edit Interference Config

Figure 4-2 shows configuring judgment criteria for abnormal interference in Nastar.

Figure 4-2 Configuring judgment criteria for abnormal interference in Nastar

BaseNoise indicates the judgment criteria for abnormal interference is based on the self noise figure of main, diversity, or a proper noise figure specified by the customer.

Beyond base noise It indicates the relevant noise threshold. If the interference is stronger than the threshold by Beyond base noise, the interference is effective.

Duration indicates the duration threshold for effective interference Interference Counter indicates threshold of the interference times. If the

interference times is more than Interference Counter, the cell is interfered.

4.2 Judging Types of Interferences

4.2.1 Criteria for Judging Interferences

I. Interference Types

The interference includes internal interference and external interference.



The interference occurring on NodeB to the antenna-feeder system is internal interference. The specific internal interference might be:

Intermodulation due to participation of transmitted signals The transmitted signals interfere receiver band due to problematic transmitters and

the receiver encounters self-excitation Intermodulation and unlocked phenomenon generated by transmitted signals inside

the receiver RTWP problem due to improperly configured NodeB RF

The external interference includes in-band signal interference and out-band strong signal interference. The typical types are personal handyphone system (PHS) interference, repeater interference, interference from handset interferer.

II. Criteria

The interference belongs to external interference if it meets the following judgment criteria:

The interference to main or diversity is relevant. Namely, in terms of time, the interference to main or diversity trends similarly, and the difference between them is within 5 dB.

The external interference affects multiple cells that are geographically bordering. In terms of time feature of RTWP, the external interference is mutational, the

interference occurs at a regular point and in a regular period, and lasts for a regular period (exceptions are microwave interference, improperly configured gain of repeaters, so the RTWP is not mutational)

The interference which is not external interference is internal interference, so it follows the internal interference processing procedures. Locating external interference takes more effort and time than locating internal interference. Therefore, if the interference is not confirmed to be internal interference, it must be rechecked.

The inter-modulation interference which takes a high ratio in internal interference features typically as below:

The RTWP of main and diversity is usually irrelevant. If the RTWP is relevant, there must be special causes, such as the main and diversity are combined at some point.

The interference is related to traffic. The interference occurs less probably when traffic is lower.

The RTWP fluctuates sharply, as great as about 10 dB, or even greater than 10 dB. The interference will last for a period, without mutational change, which is different

from that of external interference. In terms of time feature of RTWP, the RTWP changes irregularly.

The intermodulation usually meets one or more of the previous five features. If the five features are all met, it must be intermodulation.

For better understanding of the previous judgment criteria, the following examples provide direct phenomena of various interference from actual networks. Therefore no specific locating process is provided.

4.2.2 Sampling RTWP Variation Due to Internal Interference

I. Multi-frequency Intermodulation Due to Load

In an indoor distributed system, the 3G signals, 2G signals of the operator S, and 2G signals of the operator P are combined. The operator P uses the absolute radio frequency

channel number (ARFCN) 747. The operator S uses the ARFCN 850 and hopping frequency ARFCN 815.

Figure 4-3 shows the variation of RTWP.



Figure 4-3 Variation of RTWP due to load

The interference in the cell is caused by a load with loose connection. Once the load is touched, the RTWP changes sharply.

The RTWP changes as below:

The main and diversity are irrelevant The RTWP fluctuates sharply The interference lasts for a period The RTWP changes irregularly in terms of time

II. Multi-frequency Intermodulation Due to Improper Connection of Multiple RF

The multiple RF connection involves duplexer, feeder, and jumper connector.

The site is constructed with indoor distribution system shared by multiple operators. The antenna-feeder structure is complex. Wherein, multiple hybrid couplers, feeders, and jumpers are improperly connected, so the RTWP is as shown in Figure 4-4.

Figure 4-4 Variation of RTWP due to improper connection of multiple RF


The RTWP fluctuates sharply The interference lasts for a period The RTWP changes irregularly in terms of time



III. Single Frequency Intermodulation Due to Improper Connection of Feeder and Jumper

The 3G signals and 2G signals are combined. The 2G network uses only one channel number. Intermodulation occurs due to improper connection of feeder and jumper.

Figure 4-5 shows the antenna-feeder structure.

Figure 4-5 Antenna-feeder structure

Figure 4-6 shows the variation of RTWP due to improper connection of feeder and jumper.

Figure 4-6 Variation of RTWP



IV. Multi-frequency Intermodulation Due to Interaction of 2G and 3G signals

This is an indoor site, with 2G and 3G signals combined. It is an indoor distributed system shared with other operators.

Figure 4-7 shows the variation of RTWP due to interaction of 2G and 3G signals.



Figure 4-7 Variation of RTWP due to interaction of 2G and 3G signals

In Figure 4-7, the main interference (in red) is caused by intermodulation of DCS signals and 3G signals at a connector.

Note:

The diversity is not connected to antenna. The external signals near cabinet interferes diversity.



4.2.3 Sampling RTWP Variation Due to External Interference

I. Sites Around Repeaters of Self-excitation Interference

Figure 4-8 shows the site distribution around the site 501800.



Figure 4-8 Site distribution around the site 501800

In the network as shown in Figure 4-8, a 3G repeater close to the NodeB 501800 transmits a self-excitation signal every hour approximately. Therefore the uplink in multiple cells is interfered. The uplink interference varies according to the direction and the distance between the cell and the repeater. However, it is clear that the uplink interference occurs every hour approximately.

Figure 4-9 Variation of RTWP in adjacent cells (1)





Note:

The site 501800 is an indoor site with a single antenna.


The main and diversity are relevant The interference influences multiple cells that are close to each other The interference is mutational The interference changes with a regular internal

II. Uplink Interference to Host Cell Due to Repeater Self-excitation

The NodeB 45680 uses a 3G repeater. The host cell of the repeater is the first cell 54291 of the NodeB 45680. The occurrence time of self-excitation of the repeater is irregular.

Figure 4-15 shows the RTWP variation of cell 54291.



Figure 4-15 Variation of RTWP


The main and diversity are relevant The interference is mutational

III. Uplink Interference to Host Cell Due to Improperly Configured Gain of Repeater and Self-excitement

The gain of the repeater is 90 dB. Figure 4-16 shows the RTWP variation of cell 45680.

Figure 4-16 RTWP variation of cell 45680

After adjustment of the repeater gain to 70 dB, the RTWP becomes normal.

The RTWP variations feature the same as that of improperly configured gain of repeater. Namely, the interference is strong and stable.

IV. Uplink Interference to 3G Antenna Due to Close Radiation from 2G Repeater Antenna

The 3G antenna is interfered by a 2G repeater antenna another operator. The 3G antenna uses space diversity. As shown in Figure 4-17, the 3G antenna is a diversity antenna and the main antenna is far from 2G antenna.



Figure 4-17 Antenna location

Figure 4-18 RTWP variation


The main and diversity are relevant The interference is mutational

V. RTWP Variation Due to Passing Trains

The NodeB is close to the railway with intensive trains passing by.

Figure 4-19 shows the site location near the railway.



Figure 4-19 Site location

Figure 4-20 RTWP variation of a NodeB near railway

VI. Uplink Interference Due to State Switch of Indoor Air-conditioner Controller

Figure 4-21 shows the uplink interference fluctuation upon state switch of indoor air-conditioner controller.

Figure 4-21 RTWP variation due to indoor air-conditioner

天线



VII. Uplink Interference Due to Power On or Off of Outdoor Air-conditioner of Other Operator

Figure 4-22 shows the RTWP variation due to power on or off of outdoor air-conditioner of other operator

Figure 4-22 RTWP variation due to power on or off of outdoor air-conditioner of other operator

VIII. Uplink Interference Due to Power On or Off of Indoor Emergency Lights

Figure 4-23 shows the RTWP variation due to power on or off of indoor emergency lights, marked in red.

Figure 4-23 RTWP variation due to power on or off of indoor emergency lights

IX. Uplink Interference with Period of 200 Seconds

This uplink interference is probably due to air-conditioner compressor, but this cannot be confirmed due to property restriction.

Figure 4-24 shows the long-time RTWP variation.



Figure 4-24 Long-time RTWP variation

Figure 4-25 shows the short-time RTWP variation.

Figure 4-25 Short-time RTWP variation


The main and diversity are relevant The interference is mutational The interference changes with a regular internal

X. Interference Caused by the Spectrum Analyzer YBT250 at 1924.3 MHz

Figure 4-26 shows the interference caused by the spectrum analyzer YBT250 at 1924.3 MHz when the directional antenna approaches the YBT250.



Figure 4-26 Frequency spectrum when the directional antenna approaches the YBT250

When locating interference, pay attention to the feature of YBT250.

XI. Uplink Interference Due to Transmission Line

Figure 4-27 and Figure 4-28 show the uplink interference due to transmission line.

Figure 4-27 Uplink interference due to transmission line (1)

Figure 4-28 Uplink interference due to transmission line (2)



XII. Interference Like Self-excitation

Figure 4-29 shows the long-time RTWP variation of the interference like self-excitation.

Figure 4-29 Long-time RTWP variation of the interference like self-excitation

Figure 4-29 shows the short-time RTWP variation of the interference like self-excitation.

Figure 4-30 Short-time RTWP variation of the interference like self-excitation

Figure 4-31 shows the frequency spectrum feature.

Figure 4-31 Frequency spectrum feature



Figure 4-31 is a static figure. Its frequency spectrum features as below:

The scanned frequency ranges from 1914 MHz to 1951 MHz The amplitude of different frequencies is different The frequency jumps after a scanning period


The main and diversity are relevant The interference is mutational.

4.3 Equipment and Documents Needed In Interference Test

I. Sturcture of Interference Test

The interference test uses the following structure of test equipment.

Figure 4-32 Structure of interference test

II. Equipment and Documents

Table 4-1 lists the equipment and documents used in interference test.

Table 4-1 Equipment and Documents

Equipment or document Type of connector

Directional antenna N-type female connector

Omnidirectional small antenna SMA-type female connector

Bandpass filter N-type female connector

YBT250 spectrum analyzer N-type female connector

1/2 jumper x3 N-type male connector

1/2 jumper x2 N-type male connector/SMA male connector

50 Ohm matched load x2 N-type male connector



DIN-type male connector -> N-type female connector x2

DIN-type female connector -> N-type female connector x2

N-type dual-female connector x2

Laptop (installed with NodeB LMT software)

GPS

North-stabilized indicator

Test car

FNE map of sites

Historic RTWP map of sites

Distribution map of adjacent sites

Camera

PHS handset (if to locate PHS interference)

4.4 Locating Internal Interference

Locating internal interference includes initial location and on-site location.

4.4.1 Initial Location

The initial location proceeds as below:

1) Check the configuration of diversity reception if you fail to observe the diversity signals. Figure 4-33 shows the RTWP variation when the diversity reception is not configured.



Figure 4-33 RTWP variation when the diversity reception is not configured

2) If the uplink RF channel has not been adjusted, check whether the configured gain (especially TMAs are used) of RF channel is correct. It is good to adjust uplink RF channel so that these problems will not bother locating interference.

3) If a DCS1800M network and a WCDMA network are combined, you must check the frequency configuration with operators. Meanwhile you must check whether the third order intermodulation (2f1-f2 and 2f2-f1) of the combined DCS1800M frequency is within the RX inband (1920 MHz to 1980 MHz). If yes, negotiate with operators to change the improper frequency configuration.

If the interference remains after the previous operations, you must locate interference on site.

4.4.2 On-site Location

The on-site location proceeds as below:

1) Start NodeB LMT and measure the realtime RTWP of the cell to be located. This allows you to observe realtime RTWP variation after using consequent locating methods.

2) If a DCS network is combined to a WCDMA network, you must know the DCS carrier features (the carriers on a channel, the channel number, and the channel where BCCH is) and mark the BCCH channel.

3) If a DCS network is combined to a WCDMA network, you need adjust BCCH to the channel where interference is located under assistance by the operator according to the result of interference. The reason is that if BCCH does not use the problematic



channel (The GSM network might transmit signals in both channel, but the BCCH uses only one channel)

4) Knock every RF connector gently on the channel (especially the connectors of jumper, load, and antenna) and check the RTWP variation. If RTWP changes, the connector is problematic. Tasks to improve project quality, such as fastening connectors and reconnections, must be perform under cooperation of the operators' engineers. Ensure to power off power amplifiers of corresponding cells before performing tasks to avoid radiation injury.

5) When the connector are normal and interference is present, use YBT250, filter, and directional antenna to check at WCDMA antenna whether interference signals are received (for requirements on filter and directional antenna, see W-Electromagnitic Interference Test Guide. In special situations, you must customize the filter according to the local WCDMA receiver band and other radio network transmission frequency band). If YBT cannot detect special interference, you need change the NodeB antenna and check whether the interference is caused inside the antenna. If the interference still exists after changing antennas, turn to judgment of interference types.

6) If interference signals are receives at the WCDMA antenna by using YBT250, filter, and directional antenna, you can solve the problem by locating external interference.

7) If the interference cannot be located after repeated checks, solve it by judging interference types. Stop on-site location and restore the original configurations.

8) Record the previous locating steps in the form of "xx Interference Location Detailed Record". If successful in locating the interference, you can summarize the problem in the

form of interference location cases based on "xx Interference Location Detailed Record". Send the cases to the Headquarter for filing.

If failing in locating the interference, you can send the "xx Interference Location Detailed Record" to technical support engineers in the Headquarter for help.

4.5 Locating External Interference

4.5.1 Preparations before On-site Location

It is hard to know when the external interference appears or disappears, so detailed preparations and analysis must be performed before on-site location. Otherwise, the on-site location will be less efficient.

I. Needed Data

You need the following data:

The RTWP data for 7 (days, at least 3 days) x 24 (hours) of cells to be located The data is obtainable in "Collecting Data and Confirming Interference" section.

The MapInfo map of site distribution, the relative location of sites, and the distance between sites You can use Nastar to obtain these information.

Antenna azimuth and height of cells Photos for surveying sites Whether the cell to be located is the host cell of a repeater The distribution of 2G and 3G repeaters around the cell to be located The distribution of PHS BTSs around the cell to be located The antenna-feeder structure diagram of the cell to be located

II. Needed Analysis and Initial Conclusion

Analysis: the long-time feature and short-time feature of RTWP data for the cell to be located in different periods



Conclusion: the locating time (the periods when interference occurs intensively is obtainable according to RTWP time feature.

Analyze the following aspects:

1) Analyze the long-time feature and short-time feature of RTWP data for the cell to be located in different periods

2) Analyze the environment of the cell to be located with cell distribution diagram and surveying photo

3) Analyze the relativity of main and diversity of the cell to be located according to the antenna-feeder structure diagram

4) Use angle of arrival (AOA) to summarize the RTWP data of the cell to be located, the RTWP data of adjacent cells, antenna azimuth, and antenna height so that the location of the interference source can be estimated.

Locate the direction of the interference source by cell antennas of multiple NodeBs. Draw on a map, the crossing point of the direction of each antenna is the interference source.

Figure 4-34 Locating interference source by using AOA

Conclusion: where to locate.

III. Methods and Procedures for On-site Location

On-site location proceeds as below:

1) Start NodeB LMT and monitor realtime RTWP of the cell to be located for the features and time when the external interference occurs.

2) Check the environment of the antenna for metal blockings, antenna of other networks or systems, the antenna distribution of other operators. Check the potential adjacent blockings to signals.

3) Measure the interference strength, direction, and frequency spectrum by using YBT250, filter, and antenna.

4) Find the rough location of the interference source by using one or more of the following methods:



Middle location Determine the possible location of interference according to RTWP statistics and environment. Perform bidirectional test around the interference source to approach the source. This is called the middle location.

Figure 4-35 Schematic drawing of middle location

Two-point location The precaution for this method is that you must know the approximate interference direction. In the direction, measure the signals to compare the signal strength in two selected spots. Locate the interference by calculating the variation of interference strength. To use the variation of signal strength for interference location, you must know the direction and approximate location of interference. Then move a omnidirectional antenna to the interference and judge the location relationship between the omnidirectional antenna and the interference. Finally fix the specific location of interference near the interference source by using the directional antenna.

Figure 4-36 Schematic drawing of two-point location

5) Fix the potential interference source according to the previous analysis. 6) Verify the relationship between the interference and the state variation of the

potential interference source (such as on, off, starting, and stopping) For the equipment that is controlled by the operator, such as repeaters, you can verify the relations between the equipment and the interference by powering on or off the equipment in a proper time. For the uncontrollable equipment, you need to wait to observe the interference.

7) Record the previous locating steps in the form of "xx Interference Location Detailed Record". If successful in locating the interference, you can summarize the problem in the

form of interference location cases based on "xx Interference Location Detailed Record". Send the cases to the Headquarter for filing.

If failing in locating the interference, you can send the "xx Interference Location Detailed Record" to technical support engineers in the Headquarter for help.

The interference location detailed record template is attached.



Chapter 5 Interference Elimination

The methods for eliminating interference include, but not limit to:

Improve the project quality of the antenna-feeder system by the operator's engineering department

Optimize the frequency configuration of DCS by the operator's RF department Eliminating external inference, such as PHS interference, repeater interference, and

interference from UE interferer, is difficult for equipment vendors, so it must be under the cooperation of equipment vendors and the operator.



Chapter 6 Interference-related Cases

6.1 A Intermodulation Interference Case

The intermodulation is caused by:

Internal interference Improper configuration of frequency of combined DCS system Problematic feeder connector

6.2 Repeater Interference Case 1

The external interference and abnormal operation of DCS repeaters influence the adjacent 3G NodeBs.


The external interference and self-excitation of DCS repeaters influence the adjacent 3G NodeBs.


The external interference and improper configuration of repeater gain influence the host cell.

6.5 Interference Location Cases in Indoor Distributed System

The internal interference and problematic matched load used in indoor distributed system cause interference.

6.6 PHS-to-WCDMA Interference Location Cases

The external interference and PHS influence the WCDMA system.



Chapter 7 Introduction to Locating Downlink Interferences

The downlink interference influence a small number of UEs and the areas affected by the interference is scattered. A fixed interference source only influence a very small area and it is eliminated only in specific situations (subscribers' complaints and influencing KPIs).

7.1 Locating Downlink Interference

When the RSCP is strong and Ec/Io is weak upon cell coverage analysis, not due to pilot pollution after confirmation, downlink interference is possible.

7.2 Analyzing Downlink Interference

When the downlink interference is located, the interfered areas are clear by using geographic display function of RNO tools. Therefore, go to the interfered areas with YBT250 for confirmation. For detailed usage of YBT250, see W-Apparatus Usage Guide.

7.3 Eliminating Downlink Interference

If eliminating the interference is difficult for equipment vendors, so it must be under the cooperation of equipment vendors and the operator.

7.4 Downlink Interference Cases

Indoor infrared equipment causes downlink interference.



Chapter 8 Appendix 1: Basic Knowledge about Interference

8.1 Definition of Interference

The signals that influence a communication system in the network are interference signals. The unnecessary signals for the communication system are also interference signals. In addition, the non-system internal signals which are present in RX inband but do not influence system operations are also interference signals.

8.2 Interference Influence

8.2.1 Influence on Sensitivity

The continuous interference causes RTWP to increase by the same amount as the sensitivity decrease by. The influence on sensitivity by the purse interference is related to duty ratio of pulse width interference. Different pulse width and duty ratio have different influence on sensitivity. The interference on sensitivity by pulse interference is unrelated to the influence on RTWP by RTWP. Actually most interference has little impact on sensitivity.

8.2.2 Influence on Algorithm

The pulse interference influences the RTWP-related algorithm, such as admission control, congestion control, and load balance.

8.2.3 Influence on System

All interference influences the system in different aspects, such as sensitivity and algorithm.

8.3 The source and features of Interference

8.3.1 Internal Interference

The internal interference includes:

Interference related to transmitted signals and intermodulation due to transmitted signal participation

Interference related to transmission channels It seldom occurs that the transmitted signals interfere with RX band due to broken power amplifier. However, when the power amplifier is broken, the transmitter becomes problematic. Therefore the transmitted signals interfere with RX band. The cause to the problem is multiple stage intermodulation. Internal interference is usually unrelated to the reverse intermodulation of transmitter but related to passive devices. The self-excitation in RX inband brings more interference. The spectrum expansion: the power amplifier is abnormal, so the spectrum is expanded to RX



inband. The unlocked situation: the frequency drifts to RX inband. The possibility of occurrence of problems on the transmitter is smaller than 1%.

Interference related to receiver channels, receiver self-excitation, intermodulation caused by transmitted signals within the receiver, unlocked situation, abnormal RTWP caused by unfixed frequency, and congestion caused by strong signals.

8.3.2 External Interference

I. Other Communication Systems

The interference does not exist in normal situations. It exists in those countries with improper allocation of spectrum. You need to pay attention to the interference only when the frequency in band 1 and band 2 is used in the same area. If a country for band 1 uses the frequency in band 2, interference appears, which are destined to appear. Therefore this interference must be known upon network construction with known influence.

1) Interference to WCDMA system by PHS system Basic features of domestic PHS system

According to the RCR STD-28 standard, the carrier bandwidth of PHS is 300 kHz, with a frame per 5ms. A frame is divided to 8 timeslots, with the timeslot structure shown in Figure 8-1.

Figure 8-1 Frame structure of PHS system

Note:

The uplink and downlink protection interval is 4.7us.

According to related rules and RCR STD-28 standard, the PHS frequency range is 1900.1–1915.0 MHz. In some place, the frequency may reach 1918 MHz, which is beyond the range.

The PHS system uses continuous dynamic channel selection as an important advantage. The base transceiver station (BTS) automatically measures the interference within the working frequency band and automatically select the channel with minimum inference for talk. When the interference to the serving channel is so strong that continuous work is impossible, the BTS reselects new channel for talk or even enable the MS to handover to another BTS. Therefore the continuous dynamic channel selection is of high utilization of spectrum.

The PHS BTS transmits signals that are selected one from four and receives four-path combined signals with maximum ratio.

Technical parameters of PHS system

Table 8-1 Technical parameters of PHS system

BTS transmit power (peak)

4000 mW (average: 500 mW) 80 mW (average:

10 mW)

Antenna gain 9 dBi 0 dBi (body loss)

Diversity gain Transmit: 3 dBi; receive: 9 dBi 0 dBi



Needed C/I 10 dB 19 dB

Adjacent channel leakage power

2 * Δf < 800 nW

3 * Δf < 250 nW

Scatted transmission

<250 nW/300kHz in 1893.5–1919.6 MHz,

<2.5 μW/MHz out of 1893.5–1919.6 MHz

Serving bandwidth 288 kHz 288 kHz

Receiver sensitivity < 16 dBμ (–97 dBm, 1 * 10 – 2)

Range of receiver signals

16–80 dBμ (–97 to –33 dBm)

Selectivity of adjacent channels

2 * Δf: > 50 dB

Level monitored by carrier

Level 1: 26 dBμ

Level 2: 44 dBμ

Basis features of PHS interference Time feature

It is related to PHS traffic and is in pulse signals. It marks the users' behavior. The RTWP might increase for about 20s. No interference is in half of a 5ms period. The timeslot feature of interference meets the timeslot feature of PHS.

Frequency feature The interference is strong in low-frequency band but weak in high-frequency band. Great burst RTWP in large quantity increases. The interference occurs frequently and becomes stronger between 1920 MHz and 1930 MHz. When the frequency changes to be a higher frequency, the interference occurs less frequently and becomes weak. The PHS interference signals are noise signals.

Space feature The PHS BTS nearby transmits weak interference signals. The BTS 10–50 meter far transmit strong interference signals. If the heights of two antennas are close (the further one antenna from another is, the weaker the interference between the two antennas are due to the difference of antenna heights), the BTS which the angle between WCDMA antenna direction and PHS BTS direction is smaller than 60° transmits strong signals.

Polarization feature The interference signals are vertical polarization signals. The signals transmitted on the two antennas are similar.

Modulation feature The interference is non-modulation feature noise.

Pulse feature (short-term feature) The occurrence of interference is closely related to the occurrence of PHS signals. No interference exists in half of the time.

Strength feature The interference strength changes sharply from the maximum RTWP according to the statistics to the noise level.

Affected range feature The Interference affects one or two sectors of BTS.

RTWP statistics feature of PHS



The impact on WCDMA NodeBs by PHS is closely related to the number of PHS interfered users. The RTWP varies with the number of users. Affected by PHS system, in the statistics RTWP, the RTWP is completely related to traffic and user behaviors. The RTWP keeps increasing for about 20s.

According to scanned RTWP diagram, with PHS interference, the scanner RTWP diagram is related to the number of PHS users. When there are many PHS users using a frequency, the RTWP increases sharply. Therefore the statistics data is sawtooth.

The RTWP of WCDMA fluctuates sharply in the working period of PHS, and high RTWP peaks appear in 1920–1930 MHz. It is similar in other RX bands of WCDMA, but the peaks occur less probably. Therefore, WCDMA NodeBs interfered with by PHS have RTWP peaks.

The BTS interfered by PHS has relevant main and diversity in terms of RTWP.

Impact on system by PHS interference PHS has less impact on system sensitivity than on RTWP. The interference can be ignored if its impact on RTWP is within 5 dB. PHS BTSs have little impact on WCDMA, especially when the PHS

antenna and WCDMA antenna are far away or near. Knowing the location of PHS sites upon WCDMA site construction

effectively helps to reduce PHS interference. Elimination of PHS interference

You can see by connecting multiple MSs to PHS system that the RTWP strength is related to access of the MS. To eliminate PHS interference, move the WCDMA antenna to PHS antenna as close as possible. The height of WCDMA antenna should be higher or lower than PHS.

2) Interference between GSM and WCDMA The interference between GSM and WCDMA is usually too weak to be considered. One exception is the interference between WCDMA 2100 MHz and GSM 1900 MHz, which cannot coexist. Instead, you can use WCDMA 1900 MHz or WCDMA 1700 MHz. Another exception is the interference between WCDMA 1800 MHz and GSM 1900 MHz, which also cannot coexist. Instead, you can use WCDMA 1900 MHz or WCDMA 1700 MHz. If a country using GSM1900 MHz constructs a network of WCDMA 2100 MHz, the following problems occur: The signals transmitting by GSM network of 1900 MHz interferes with the

receiving by WCDMA network, so you must use a narrowband transmission filter. This is easy. A 1900 MHz BTS uses a narrowband filter. If it uses a non-narrowband filter, a filter needs to be added on the top of the BTS.

WCDMA UEs transmit signals that interfere the signals from GSM MSs. When a WCDMA UE is transmitting signals, the GSM MSs nearby cannot make a call. This is difficult to be predicted and felt. In later stage of the network, it may be a critical problem. If the system in which GSM and WCDMA coexist is constructed by no other means, operators must be informed of this problem. Interference features

The interference sources are spreading, namely, widely and irregularly distributed in the whole area. Interferences are similar. A site with interference is not far away from other communication systems.

Interference location Check the spectrum distribution of the communication system. Check the relative location between BTSs. Check whether the wide-range statistics feature of RTWP is discrete. Check the transmission filter bandwidth and spectrum features of another communication system.

Solutions to interference Use the proper spectrum according to normal method for allocating spectrum.



II. Repeaters and Line Amplifier

1) Causes to interference with repeaters Repeaters are designed broadband without selection of frequencies. If a repeater uses an improper host NodeB or is far from the host NodeB, the

transmit power becomes too high to interfere with other adjacent NodeBs. Repeaters are unstable, so self-excitation of repeaters occurs. Improper configuration of repeaters and gain causes noise to interfere with

UEs. 2) Causes to problematic line amplifier

The gain of line amplifier (LA) is improperly configured. LAs are unstable, so self-excitation of LAs occurs.

3) Interference features of repeaters and Las Long-term stable interference and burst interference. The interference from repeaters is a directional large-scale interference. The interference from LAs spreads in a round shape. Long-term and stable interference spectrum is systematic spectrum feature. Burst interference spectrum is variable tone signal. Locate the approximate location of the interference source according to

interference features of a cell. A long-term stable interference is probably due to improper gain. The burst interference is due to self-excitation of active device in two aspects:

there are abundant irregular bursts; the burst interference exists in a fairly short time; the interference with a fixed period exists for several seconds.

4) Solutions to interference Change the way to use repeaters to ensure frequency selectiveness of repeaters and to guarantee stable and pure host link of repeaters. Adjust the gain of repeaters to proper range.

III. Microwave Transmission

The features of microwave transmission are as below:

Long-term stable interference. The interference is bidirectional. The interference is in a large-scale range The spectrum is broadband spectrum.

Eliminating the interference from microwave transmission is adjusting the frequency of microwave transmission.

IV. All Power-Consuming Equipment

V. All Controlling Components (Especially Big Electric Controlling Components)

The features of all controlling components are as below:

The interference is instantaneous. Maybe the time feature of interference surge is present but unseen.

The interference spectrum is from 0 (direct current) to several GHz. The interference affects a small range, usually a NodeB.

VI. Equipment with Clocks

The interference from equipment with clocks exists permanently or appears irregularly. It appears irregularly due to time frequency drift caused by unlocked frequency.

The interference spectrum is tone or drift tone. The interference exists in other transmission systems. Locate the approximate location of interference by using the features that

interference affects a cell.



VII. Non-linear Components in Great Electromagnetic Field

The features are as below:

The interference from non-linear components in great electromagnetic field is due to the PIM occurring on high-power transmission equipment. It is related to high-power transmission equipment.

The time feature of interference is related to work features of high-power transmission source.

The interference frequency includes broadband interference frequency and frequency meeting intermodulation conditions.

The interference affects a limited range, namely, a single cell.

VIII. Radar


The interference from radar is regular in period. It is pulse interference usually multiple periods.

Its spectrum has features of a SINC factor. It affects a wide range. Locate the approximate location of interference by using the feature that


IX. Handset Interferer


The interference from handset interferer exists for a certain period or for a long time, such as only during a daytime meeting. It features apparently in terms of time.

The interference spectrum has broadband features. The handset interferer is used by government, military, hospital, and gas stations. The outdoor antennas that receive the interference signals lie in spherical points. Locate the approximate location of interference by using the feature that


X. Intermodulation Signals from Various Transmitters (Especially TV Station)

The intermodulation signals from various transmitters, especially television station, features as below:

The signals are modulated, from which the features of carrier and modulation spectrum are distinguished.

The interference signals are stable and permanent, or exist intermittently. The interference affects a large range. Locate the approximate location of interference by using the feature that


XI. Large Equipment with Great Instant Variation of Electricity


The electricity changing instantly is the precondition of generating high-frequency signals. The size is the precondition of transmission capacity.

When the electricity changes, the interference occurs accordingly like pulse. The interference spectrum is broadband signals. The interference usually affects a single NodeB.

XII. Equipment with Feedback Channel (Self-excitation)

The equipment includes:

Signal source of various wireless systems Local oscillation



High-gain amplifier Repeater LA Automatic switch controlling equipment Sound-control equipment Light-control equipment

The features of the previous equipment are as below:

The interference is random. The spectrum is unstable tone spectrum. The affected range is also random.

XIII. Discharge Equipment


The features of interference are the same as the features of discharge, usually like pulse. A floodlight keeps blinking, so approximately continuous interference occurs.

The interference spectrum is broadband spectrum. The interference affects a small range.

8.4 PIM Description

The PIM appears as transmit power appears. Its spectrum and input frequency meet the mf1+/-nf2 relationship. It occurs most probably in antenna-feeder system, especially at the connector of feeder and antenna.

For connectors to feeders, a low PIM concerns the following six aspects:

Contact design Combining interface of connectors Internal connection of connectors Cable clamp device Materials and electroplate

While designing the structure of cable clamper of RF connector, increase the contact square and pressure as possible. Keep the mechanism stability of the contact interface between internal and external conducts of connectors and that of cables. Prevent the slight displacement of contact parts caused by curved cable or mechanical vibration from severe PIM.

Usually the jointing external conducts are ideal and on sale, but the majority is flared mechanical clamper. Connectors are usually assembled by operators on site, so the quality of the components is not under the quality control of connector manufacturer. Therefore consider the assembling conditions upon design, draw accurate cable layout and dimension table. This helps to assemble the connectors and reduces assembling errors.

Avoid the following pollution source during assembling connectors:

Dust Sweat Grease Metal clast Scratch on the conductor surface

The causes to the previous pollution are nonstandard operations during assembling, package, transport, and installation. Therefore ensure to prevent pollution from existing inside components, especially the sweat, grease, the metal clast, and scratch on the conductor surface. Avoid scratch, fish tail, and impress on the surface, especially the contact surface.



8.4.1 Connection of DIN connectors

Check the connection surface and internal conductor for foreign bodies, scratches, or problematic screw thread.

I. Checking Connection

1) Insert the connector forcibly and then connect 2) Rotate the bolt while the connector and the cable are relatively fixed. 3) Check the connection for loose components.

II. Important Checklist for Manufacturing Connectors

Check the connectors whether:

The stripper is accurate The size is proper The tools for manufacturing connectors is nonmagnetic The clearing is comprehensive The plating layer is complete Process adjustment is performed according to plating layer The connectors are in good condition

8.4.2 Occurrence of Antenna PIM

I. Two Types of Nonlinear Phenomena

Two types of nonlinear phenomena include:

1) Nonlinear contact occurs upon contact of metal with nonlinear electricity and voltage. In details, it includes looseness, being oxygenated. Nonlinear materials refer to alloys, such as magnet, carbon fiber, iron, cobalt, nickel, and aluminum, has the nonlinear V-I.

2) The antenna PIM occurs closely related to the following factors: Metal is used in antenna-feeder system to enhance the structure strength and MIM

leads to occurrence of PIM. Slight cracks, crazing, and hollow inside the metal cause PIM. Nonlinear carbon fiber and planning layer. Electronic channel effect and semi-conductor effect at the contact point with metal. Impact of uneven material structure on conductivity and micro change of some

particles due to unbalanced heat (energy). The edge processing procedure of antenna and some parts, rivet connection

techniques lead to occurrence of PIM. Oxygenation, rustiness, and erosion at connection points.

8.4.3 Controlling Antenna PIM

Manufacturing controlling board of reflectors is important to occurrence of PIM. The rivet connection aluminum controlling board is most frequently used. Every rivet might cause PIM. Solve this problem by using gluing technology during manufacturing.

PIM occurs probably where the high-voltage electricity intensively exists. Designing feeder channel is key. In principle the whole-set feeder is used, but it is possible actually. The metal-to-metal contact must not be used in the feeder design. The contact electric potential difference caused by different metal contact or uneven expansion must be eliminated in antenna design. For manufacturing single chips not for electric spark erosion at feeder part, the PCB should be nonmetal board when power splitter is used. The antenna must not be mounted in an environment where the temperature changes quickly.



8.4.4 Features of Antenna PIM

1) When metal clasts exist in the feeder point, the antenna PIM features that the intermodulation outcome increases by over 20 dB and that intermodulation outcome fluctuates.

2) Metal clasts on the surface mounting components have less impact than the feeder point.

3) The reliability of grounding metal around the antenna unit affects the fluctuation of system PIM. The metal partition board between the antenna units must be grounded by multiple jointing points, not by large-square grounding.

4) Nonmagnetic materials must be used for manufacturing antennas. 5) The oxygenation layer formed by brand iron in jointing is a major cause to

occurrence of PIM. 6) Do not touch the components. Clear the connector every time after using them,

especially after test. 7) Joint the connectors to the supporting structure if the connectors will not be moved. 8) Keep the connector and cable relatively fixed during connection. 9) The connection of power splitter and ground impact PIM as much as over 20 dB, so

the reliability of connection between power splitter and ground, as well as cable, must be guaranteed.

10) Clean the exposed parts of an antenna after it is made.

8.4.5 Relationship between PIM and NodeB Alarms

1) If alarms, such as VSWR alarms and TMA alarms, occur on the antenna and feeder with power, PIM occurs.

2) PIM occurs unrelated to previous alarms. It might occur with or without alarms. Do not determine the quality of connection of antenna-feeder by testing resistance and VSWR. Normal resistances and normal VSWR is necessary to good antenna-feeder, but is far from sufficiency.

3) The gain alarms on the Rx channel are usually impossible. Thought PIM causes irrelevant main and diversity RTWP, that the NodeB receives channel alarms is less probable, usually impossible.

4) Locate the antenna-feeder problems not by alarms, but by analyzing RTWP for basic features



Chapter 9 Appendix 2: RTWP Description

9.1 RTWP Definition

The RTWP of NodeB is the uplink inband received total power, clearly defined in the protocol:

Table 9-1 Received total wide band power(TS 25.215 v600)

Definition The received wide band power, including noise generated in the receiver, within the bandwidth defined by the receiver pulse shaping filter. The reference point for the measurement shall be the Rx antenna connector. In case of receiver diversity the reported value shall be linear average of the power in the diversity branches. When cell portions are defined in the cell, the total received wideband power shall be measured for each cell portion.

According to Table 9-1, the RTWP is the inband signal strength of NodeB, with the reference point at Rx connector; the RTWP involves the noise from NodeB.

Huawei uses the reference point as shown in Figure 9-1. The reference point is point A without TMAs or point B with TMAs.

NTTA+12dB

Line -4dBNDDL AMP+38dB

NDDL ATT-8dB

NRFB-8dB

NTRX+45dB

AGC AD

DDCRRCDAGC

MON ATT-35dB

NDDL(NF2<2) NTRX (NF3=19)

B A

ANT in

MON in

ANT (NF1<2)

Figure 9-1 Structure of uplink Rx channel of V1.3 NodeB

Antenna in: the input port of antenna, from which the signals S and PN are input. MON in: the loading input port, where white Gaussian noise is input. ANT frame: including TMA NTTA and feeder. The TMA has a gain of 12 dB. The

feeder has an attenuation of 4 dB. The noise figure of ANT frame NF1 <= 2. NDDL frame: including NDDL fixed gain amplifier with gain of 38 dB. The range of

the adjustable attenuation is 0–12 dB, which counteracts TMA gain and feeder attenuation. The white Gaussian noise for loading is input from the monitoring port. After attenuation of 35 dB is input, it is combined to uplink Rx channel. The NDDL NF2 <= 2.

NRFB: the backplane and connection line are combined as a frame, with an attenuation of 8 dB.

NTRX: its uplink gain is 45 dB. Its noise figure is NF3 = 19. AD sampling is performed on signals after passing AGC. Digital intermediate frequency is processed. Gain processing is performed by DAGC. The AGC and DAGC provide a



dynamic range of 35 dB. The AGC takes effect only when signals are strong. Its gain for weak signals is 1.

The NF of ANT frame, NDDL frame, and NTRX frame mentioned previously is obtained by respective test. The NF after cascading three modules is:

NF = NF1 + (NF2-1)/G1 + (NF3-1)/(G1*G2)

The gain of the class 1 and class 2 is large, so the NF primarily depends on class 1 and class 2. Now the NF of NB is about 3.

The following paragraphs describe the unloaded and loaded conditions.

1) Unloaded condition The power spectrum density of thermal noise is –174 dBm/Hz. It is –108.16 dBm / 3.84 MHz. The working point of uplink feeder port (RF) is –108.16 dBm / 3.84 MHz. The working point of intermediate DAGC is –108.16 + 5 + NF = –30.16 dBm / 3.84 MHz. Wherein, "75" is the entire gain of uplink Rx channel.

2) Assume uplink load is present. The uplink interference margin: 3 dB (50% load) uplink feeder port (RF) working point is –105.16 dBm / 3.84 MHz.

The working point of DAGC (intermediate frequency) is –105.16 + 75 + NF = –27.16 dBm /3.84 MHz.

9.2 Uplink RF Channel Adjustment Principles

Assume:

The thermal noise at feeder port is –108 dBm. The RF amplifier NF is 3. The rated gain of RF amplifier is G0. This value is an expected and theoretic gain

for the amplifier. The actual gain of RF amplifier is G1. This value is an actual gain for the amplifier.

The difference between G1 and G0 is d (= G0 - G1).

The gain of digital intermediate is 0, needless of consideration.

When no signals are input to the feeder port and the combination end connects to the matched load, according to the digital intermediate frequency, the calculated power PI is –108 + 3 + G1. After the software obtains PI, it calculates RTWP: RTWP1 = PI - G0. Because the rated gain of RF channel is G0, the actual gain of RF channel G1 is unknown. Actually the accurate RTWP0 is P1 - G1. The accuracy of power PI calculated by intermediate is high, and the error can be neglected. RTWP1 = PI - Go = PI - (G1 + d) = PI - G1 + d = RTWP0 + d. Therefore "d" is the error of RTWP. The adjustment aims to locate "d", consequently to obtain RTWP0. The software finally reports adjusted RTWP = RTWP1 – d = RTWP0.

If the opposite end is to match the load, an unadjusted RTWP = –105 dBm, different from expected –106 dBm. This shows that the RF gain increases by 1 dB. Namely, d is 1, so an adjustment of –1 is input. The software reports –105 dBm – 1 = –106 dBm to system before reporting. The formula remains the same whatever signals are input. RTWP1 = PI - Go = PI - (G1 + d) = PI - G1 + d = RTWP0 + d. After adjustment, the system will report correct RTWP value if ambient temperature remains the same.

The adjustment for different versions of NodeB is different. The V12 NodeB and previous versions of NodeB involve the RF channel gain of actual adjustment, which enables RTWP to restore to the rated value. The V13 NodeB has no gain adjustment components of RF channel, and instead it adjusts the RTWP value before the software reporting and the actual RF gain remains the same. The slight change (+/- 4 dB) of RF gain has neglectable impact on system performance. The RF channel gain is high, so the receiver



NF is approximately fixed under this gain variation. The RTWP compensation of V15 NodeB or higher versions of NodeB have it added before data reporting.

9.3 RTWP Error and Accuracy

Table 9-2 lists the requirements. The NodeB will perform better than this.

Table 9-2 Absolute accuracy requirement

Parameter Unit Accuracy [dB] Conditions

Range

Io dBm 4 –103<= Io <= –74 dBm

Relative accuracy requirement

The relative accuracy is defined as the Received total wideband power measured at one frequency compared to the Received total wideband power measured from the same frequency at a different time.

Table 9-3 Relative accuracy requirement

Parameter Unit Accuracy [dB] Conditions

Range

Io dBm [0.5] For changes <= 5.0dB and –103 <= Io <= –74dBm

Received total wideband power measurement report mapping

The reporting range for Received total wideband power (RTWP) is from -112 ... -50 dBm.

In following table the mapping of measured quantity is defined. The range in the signaling may be larger than the guaranteed accuracy range.

Table 9-4 Received total wideband power measurement report mapping

Reported value Measured quantity value Unit

RTWP_LEV _000 RTWP < -112.0 dBm

RTWP_LEV _001 -112.0 RTWP < -111.9 dBm

RTWP_LEV _002 -111.9 RTWP < -111.8 dBm

… … …

RTWP_LEV _619 -50.2 RTWP < -50.1 dBm

RTWP_LEV _620 -50.1 RTWP < -50.0 dBm

RTWP_LEV _621 -50.0 RTWP dBm

When the actual RTWP is smaller than the value –112 prescribed by protocol, the NodeB O&M system will not record its RTWP upon RTWP tracing.



9.4 RTWP Effect

The protocol defines the requirements on measurement accuracy of RTWP. The relative accuracy is +/- 0.5 dB. The absolute accuracy is +/- 4 dB. The protocol recommends using RTWP as admission control algorithm. Initially the RNC uses RTWP as admission control algorithm, so the NodeB must perform corresponding adjustment to conform the accuracy requirements on admission control. Actually the RTWP is affected by both accuracy of RF channel gain and external interference, which is frequent, especially on the operator S. Therefore Using RTWP as admission control algorithm is irrational. The RNC must use other admission control algorithm, so the RTWP should have less effect. Actually it is in this way.

The prior admission algorithm for RNC is not RTWP-based, which is a candidate algorithm. RTWP helps to judge whether the NodeB is affected by uplink interference and the location effect upon uplink interference.

The following paragraphs list the standard RTWP value of Huawei serials of NodeB with or without TMAs.

1) If all NodeBs are not equipped with TMAs, the antenna matches NodeBs, the system is adjusted, and no external signals interfere with the system, the RTWP is about –105.5 dBm. If the RTWP is beyond –105.5 dBm +/- 2 dB, the causes might be: The system adjustment is problematic, so the set gain of system is different

from the actual gain. The connection of antenna and feeder is problematic. External signals interferes the system.

2) If all NodeBs are equipped with TMAs, the antenna matches NodeBs, the system is adjusted, and no external signals interfere with the system, the RTWP is about –105.5 dBm. If the RTWP is beyond –105.5 dBm +/- 2 dB, the causes might be: The system adjustment is problematic, so the set gain of system is different

from the actual gain. The connection of antenna and feeder is problematic. External signals interferes the system. The attenuation of RF front end is problematic after adding TMAs.



List of Reference

[1] 3GPP, 25.215 3GPP 2001/06 protocol

[2] 3GPP, 25.133 3GPP 2001/06 protocol