Installation Manual Part 5

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Table Of Contents

RF Center Frequency and Interference Analysis Guidelines
- Before You Start
  - Overview
  - Required Equipment
- Spectrum Analyzer Settings

PRELIMINARY

D-1

BWX 8415 Basestation Installation and Commissioning Guide

OL-19519-01

APPENDIX

RF Center Frequency and Interference Analysis

Guidelines

Reference: RF Center Frequency and Interference Analysis

These guidelines are intended for an experienced and Cisco qualified specialist Field Engineer to gather

data for RF Engineering purposes. The procedures that are described are performed in order to make a

determination of basestation center frequency and possible interference points. Please refer to all

regulatory information for your region prior to performing these procedures.

Before You Start

Overview

An RF interference analysis is usually called for under two conditions. One is when it is used for

evaluating a candidate BWX 8415 Basestation (BS) site prior to deployment of equipment. We refer to

the interference testing under these circumstances as a Pre-installation Test. The second is the

Post-installation Test, when data is collected to determine (a) if there is any interference in the area at

all; or (b) the source, or cause, of known interference in the area of the installed and operational site. As

is obvious from the name of this test, it occurs after the basestation has been deployed and turned up.

The instructions in this document assume the Field Engineer is at the BS site where the testing will take

place. The data the Field Engineer gathers using the Interference Sweep procedure in this document will

be evaluated and used in the calibration of the basestation. The data will help verify and plan for noise

in the area.

To get the most benefit from this procedure, we suggest you follow these high-level steps:

Step 1: Read the entire procedure.

Step 2: Choose the correct Test configuration setup, per this procedure.

Step 3: Perform the Interference Sweep procedure.

Step 4: Send the results to Cisco or your RF Engineer.

Summary of content (20 pages)

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P R E L I M I N A RY A P P E N D I X D RF Center Frequency and Interference Analysis Guidelines Reference: RF Center Frequency and Interference Analysis These guidelines are intended for an experienced and Cisco qualified specialist Field Engineer to gather data for RF Engineering purposes. The procedures that are described are performed in order to make a determination of basestation center frequency and possible interference points.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Required Equipment You will need the equipment shown in Table D-1 to complete the interference testing. Table D-1 Required Equipment Equipment Comments HP4404B, FSH3, or FSH6 Spectrum Analyzer (or NOTE 1: If checking for 3.4/3.5 GHz spectrum, equivalent) make sure the Spectrum Analyzer reads up to 4 GHz.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Reference Level This parameter sets the level of the top line of the Spectrum analyzer display (Figure D-1). Figure E-1 shows a display with the reference level set to –50 dB and the noise floor at –104 dB. The Blue line is a display line showing a level of –103.9 dB. As you can see, the top-level line displays –50dB.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Figure D-2 -10 Reference Level Bandwidth Figure D-2 shows a reference level setting that was manually raised in the Spectrum Analyzer to –10. The blue line is the display line that was set with the original noise floor at the –50 reference level.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Figure D-3 -50 dB Reference Level with Injected Signal Figure D-4 -10 dB Reference Level with Injected Signal BWX 8415 Basestation Installation and Commissioning Guide OL-19519-01 D-5
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY The bandwidth parameter is used for the measurement and display of the signal level across a given range or span of frequencies. Within a given bandwidth there are 2 settings — one is Resolution bandwidth, and the other is Video bandwidth. To discuss bandwidth, an understanding of the Spectrum Analyzer display is needed. The display is broken out into frequencies and signal strength levels.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Figure D-6 100KHz Bandwidth Setting Time Domain Test The Time Domain test (Figure D-7) is a measurement of the duration of an incoming signal across a given bandwidth. The duration of an incoming signal affects the number of packet errors that are generated over a given period of time. The longer the duration of the signal the more packet errors are generated.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Resolution Bandwidth The resolution bandwidth parameter for the Time Domain test acts similarly to the span function in the Frequency Domain test. The bandwidth parameter opens up the receiver of the Spectrum Analyzer to look at all signals across that bandwidth for the given sweep time. The smaller the bandwidth, the more accurate the readings displayed.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Test Configurations There are two configuration scenarios used for interference testing: • Pre-installation Testing Configuration • Post-installation Testing Configuration Pre-installation Testing covers the initial equipment configurations when testing for interference at a site in order to determine whether or not the site is a good candidate for placing the BS.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY In the example above, there is 39 dB of loss. In order for the interference measurements to give an accurate indication of the environmental noise, an additional gain of over 39 dBi would need to be injected into the test. The best location for the optional LNA would be at the top of the tower prior to the main run of RF cable.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Step 1 Program the initial Spectrum Analyzer settings, per the following: a. Resolution Bandwidth = 30 KHz b. Video Bandwidth = 30 KHz c. Attenuation = 0 db d. Ref Level = -50 db e. Sweep Time = auto f. Detector Mode = positive peak g. Frequency = determined by which step you are on in the procedure Step 2 Set the frequency sweep range, as follows.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Note When you are calculating whether you need to add additional LNA, you need to have the following information. • 3.4 and 3.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Procedure The setup shown in Figure D-10 and the information below are for the post-installation test configuration. Step 1 Configure the test equipment as depicted in Figure D-10. Step 2 Program the initial Spectrum Analyzer settings, per the following. a. Resolution Bandwidth = 30 KHz b. Video Bandwidth = 30 KHz c. Attenuation = 0 db d. Ref Level = -50 db e. Sweep Time = auto f.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Interference Sweep Procedure This procedure guides you through the steps to capture the data required for the interference study. The number of steps will change with the type of antenna you are using and the frequency band you are investigating. For the Panel antenna, the number of passes through the procedure is determined by the beamwidth of the antenna.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Try to determine the polarization of the interfering signals during each sweep. To do this, flip the antenna 90 degrees. All captured measurements are with the antenna in the vertical polarization position. The frequency band to be investigated is determined by the range of the BS that is purchased by a customer. For example, the 2.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Figure D-12 Step 7 Note Max-hold Screen Capture Repeat steps 5 and 6 with the following Start and Stop frequencies. Refer to Table D-2 below, as examples. Licensed Bands – sweep only the required channel, plus the one above and the one below: Table D-2 Frequency Domain Channel Chart Licensed Bands Channel Start Stop 2.3 GHz Systems (WCS) A Channel Start Stop 3.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Licensed Bands Channel Start Stop 2.5 GHz Systems (MMDS) Channel Start Stop . . . -.0025 . . . +.0025 3.52000 3.52500 3.5 GHz Systems (WLL) 2.5005 2.5055 3.50000 3.50500 2.5065 2.5115 3.50025 3.50525 2.5125 2.5175 3.50050 3.50550 2.5185 2.5235 3.50100 3.50575 2.5245 2.5295 3.50100 3.50600 2.5305 2.5355 3.50125 3.50625 . . . -.0025 . . . +.0025 . . . -.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Frequency Domain Interference Sweeps Analysis The Frequency Domain Interference Sweep has two kinds of measurements, Max-hold and Single Sweep. First, we have to determine the theoretical noise floor. We will use the theoretical noise floor to interpret the Max-hold sweeps data. Calculating the Theoretical Noise Floor All analysis of interference is done from the theoretical noise floor.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY Time Domain Interference Sweeps Analysis The Time Domain sweeps capture how the interference sources behave, if the interference is constantly there or operating in a hopping method. Time Domain sweeps are typically used for the unlicensed 2.4 GHz systems’ interference measurements.
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Appendix D RF Center Frequency and Interference Analysis Guidelines Spectrum Analyzer Settings P R E L I M I N A RY BWX 8415 Basestation Installation and Commissioning Guide D-20 OL-19519-01