interference identification mitigation

Interference Identification and Mitigation 0. Authoring Team

Sprint PCS � Proprietary & Confidential � 5/20/02 �

Interference Identification andMitigation

Manager, RF Engineering, San Diego858-621-7118San Diego RF Engineering8/19/02

Your input is important. If you have questions, comments, or suggestionsregarding this document, contact the person listed above by e-mail or phone.Your knowledge and insight are invaluable resources for improving Sprint PCSdocumentation.

Authoring Team

Terry Kolody, RF Engineer, San Diego

Michael Erich, Senior Engineer, San Diego

Derek Yachanin, RF Manager, San Diego and Hawaii

Michael Lawson, Senior Engineer, Corporate RF

Darryl Romero, RF Technician, Southern California

Interference Identification and Mitigation 0. Authoring Team


Table of Contents

Authoring Team.................................................... 11.1. Summary of Changes .................................................... 4

1. General ............................................................. 41.2. Purpose .......................................................................... 41.3. Scope ............................................................................. 41.4. Responsibility................................................................ 4

2. Introduction ................................................... 52.1. General Information ...................................................... 52.2. Required Elements for Task Completion ...................... 5

3. Process Flowcharts....................................... 63.1. Overall Process.............................................................. 6

4. Performance Statistics ............................... 124.1. Verify Hardware operation.......................................... 12

5. Defining Interference .................................. 13PCS Spectrum Blocks .......................................................... 145.1. Isolate Approximate Area of Interference FromPerformance Statistics .......................................................... 145.2. RF Engineering Proceeds to Area and InvestigatesCause .................................................................................... 155.3. Identify Interference Type........................................... 16

6. Location of Interference ............................. 216.1. Triangulation and Location of the Interference Source.21

7. Mitigation of Interferer................................ 247.1. Turn off interfering source .......................................... 24

8. After Action Review .................................... 258.1. Update Management ................................................... 258.2. Report Generation an Submission............................... 25

Interference Identification and Mitigation 0.


9. After Action Review Reporting Format ...... 28

10. Approval Page.............................................. 29

List of TablesTable 0-1: Changes by Section Heading ......................................... 4

List of FiguresFigure 3-1: Interference Mitigation Flowchart................................ 6

Figure 3-2: Eliminate Potential Hardware Issues Flowchart .......... 7

Figure 3-3: Identify Interference Flowchart.................................... 8

Figure 3-4: Locate Interference Source Flowchart ......................... 9

Figure 3-5: Mitigate Interference Flowchart ................................. 10

Figure 3-6: After Action Review Flowchart ................................. 11

Figure 5-1: PCS Channel and Block Allocations.......................... 14

Figure 5-2: Normal Uplink Band with no Nearby Mobiles .......... 17

Figure 5-3: Normal Uplink Band with a local F1 Mobile in Call . 18

Figure 5-4: Representation of Uplink Band Interference.............. 18

Figure 5-5: Normal CDMA Downlink Carriers............................ 19

Figure 5-6: Downlink Band with GSM Carrier Interfering .......... 20

Figure 5-7: Typical GPS Downlink band...................................... 21

Figure 6-1: Triangulation Method................................................. 22

Figure 6-2: Multiple Triangulation Measurements ....................... 23

Figure 9-1: After Action Review Report Format .......................... 28

Interference Identification and Mitigation 0. 1. General


1.1. Summary of Changes

Table 0-1: Changes by Section Heading

Section # Description of Change

All Final Draft complete (TK) – May 20, 2002

5 Process tuned with results from San Diego RF Pilot test.

2.2 Added Analog Phone to equipment list. – August 19, 2002.

5.2 Modified procedure based on Chicago Pilot Test – August 19, 2002

7.1/7.1.1 Modified wording to clearly indicate procedure - Online Feedback – Dec 6,2002

5 Added MTA/BTA and Auction web site link.

7.1.3 Changed Core RF Contact number – December 17, 2002

1. General

1.2. PurposeThe propose of this document is to provide a procedure for identifying, locatingand mitigating harmful interference to the Sprint PCS CDMA network.

1.3. ScopeThis document contains the Sprint PCS recommended interference identification,location and mitigation procedures.

1.4. ResponsibilityThe San Diego RF Manager will be responsible for maintaining this document.Contact the San Diego RF manager at 858-621-7118.

Interference Identification and Mitigation 2. Introduction


2. Introduction

2.1. General Information

CDMA is an interference-limited technology. Generally when, we speak ofinterference, we speak of it as it relates to the interference generated by mobiles inthe current sector, or adjacent sectors. However, any other source of interference(Io) can have a dramatic impact on system capacity, coverage and performance.

Generally, there are two broad classes of interference that have an impact onsystem performance. The first type is broadband spectral interference which willcauses a rise in the overall noise floor (Io) and can also impact the coverage areaof the mobile. Typically this type of interference is caused by the environmentalconditions in which the BTS receiver resides. For example, the ambient noisefloor for a suburban or urban cell generally is higher than that for a rural cell site.

The second type of interference is that caused by a transmitting device that can actas a jammer when it appears in band. This type of interference is harmful tonetwork performance. This document deals with finding and mitigating thesesources.

2.2. Required Elements for Task Completion

To complete this process and successfully locate and mitigate an interferer youwill need the following gear:

• Spectrum Analyzer capable of scanning 1400MHz-2000MHz

• Directional Antenna – (Small Yagi or other panel antenna)

• Magnetic Compass

• Maps of the interference area

• Protractor

• Dual mode PCS phone in Analog mode.

Interference Identification and Mitigation

3. Process Flowcharts

Sprint PCS � Proprietary &

Confidential

� 5/20/02 �

3. P

rocess Flowcharts

3.1. Overall P

rocess

4.1PotentiHardwaIssue

5.interferen

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7.Interferen

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irectionAntenna,

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area

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interferenc

5.4.1

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Interferen

5.4.Scan D

ownlinkLook

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High Drops /

Blk sym

pto

No

5.4.3

Scan GPS

LookInterferen

7.2.Turn off

8. Afterrevie

7.1.3 EscalateRequire

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5.4.4 UpdateRF M

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4.1.Net Ops verifies cellif needed. Switch techswitch / trunk

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Sprint PCS Interference Identification and M

itigation Flowchart

LossSync

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6.1.PeakSi

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easuredonM6.1.4

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6.1.3 Move

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Figure 3-1: Interference Mitigation Flowchart

Interference Identification and Mitigation 3. Process Flowcharts


3.1.1. Eliminate Potential Hardware Issues

4.1 EliminatePotentialHardware

Issues

4.1.2Faulty equipment.Repair as required.

4.1.1Net Ops verifies cell operationif needed. Switch tech verifies

switch / trunk performance

Bad Hardware

4.1.3 Inform LocalRF Manager andCore RF group of

situation

OK

5. IdentifyInterference

OK

Figure 3-2: Eliminate Potential Hardware Issues Flowchart



3.1.2. Identify Interference

5. Identifyinterference

5.2 Determine Area ofInterference from

Performance Stats

5.3 RF Visits areaimpacted with

SpectrumAnalyzer,

DirectionalAntenna, and

mobile handset.

Use handset tonarrow search

area.

Use SpectrumAnalyzer to idenfiy

interference.

5.4.1Scan Uplink Band

Look forInterference

5.4.2Scan Downlink Band


High Drops / Blockssymptoms

No

5.4.3Scan GPS Band


5.4.4 Update LocalRF Manager andCore RF group of

situation

Yes

Yes

Yes

Loss ofSync or

Timing losssymptoms

6. LocateInterference

Source

OK

Figure 3-3: Identify Interference Flowchart



3.1.3. Locate Interference Source

6. Locateinterference

source

6.1.1Peak Signal.

Measure Azimuthto Signal

6.1.2Plot Line with

Measured Azimuthon Map

6.1.4Can InterfererLocation be

Triangulated?

6.1.3 Move to aNew Location.

RepeatMeasurements

No

Can InterfererLocation be Pin

Pointed?

Yes

Move Closer to theInterferer location

and repeattriangulation

No

6.1.5 Update LocalRF Manager and

Core RF ofsituation

Yes

7. MitigateInterference

OK

6.1.5If Interference can

not be isolated,Escalate to Core

RF

No

Figure 3-4: Locate Interference Source Flowchart



3.1.4. Mitigate Interference

7. MitigateInterference

7.2.1Turn off Source?

8. After actionreview

7.1.3 Escalate asRequired.

Involve Core RF

No

7.1.2 Update LocalRF Manager andCore RF group of

situation

Yes

OK

7.1.1RF Visits

InterferenceSource

Figure 3-5: Mitigate Interference Flowchart



3.1.5. After Action Review

8. After actionreview

8.2.1 Local RFEng. Generate

After ActionReview Report

8.1.1 Inform LocalRF Manager, NetOps and Core RFGroup of situation

8.2.2 Core RFReviews ARR

8.2.3 AARDistributed to allNational Markets

8.2.4 Core RFCorresponds with

interferer. FCCescalation if

required.

8.2.2AAR Sent to San

Diego RFManager.

InterferenceMitigation processtuned as required.

Figure 3-6: After Action Review Flowchart

Interference Identification and Mitigation 4. Performance Statistics


4. Performance StatisticsAn outside interference source, such as a rogue transmitting device,typically will manifest itself in the network by causing a sharp suddendegradation in system performance of a cell, sector, or cluster of cells.

However, such a sudden degradation in system performance can also bean indicator of other problems, such as commercial power failures,traffic jams resulting from car accidents, natural disasters, etc.Interference should be investigated as the problem source only when allother logical causes for network degradation have been eliminated.

4.1. Verify Hardware operation

4.1.1. Verify proper Cell and Switch Operation

If call blocking and call dropping is only happening at a single cell site,verify the suspected bad sector/cell by connecting a spectrum analyzerto the Rx test port on the BTS. Check for any unusual noise oranomalies associated with the reverse or forward link CDMA signal.Check for GPS alarms on BTS. If interference is detected, there is notlikely to be a BTS equipment problem. Proceed with interferencedetection and mitigation procedure.

If Call blocking/dropping or GPS alarms are occurring at multiplesites, verify whether the suspected sites are in the same cluster orgeographic location. Contact the MSC and verify all commonhardware (trunks, MUXes, Frame Relay shelfs, etc.) is operational. Ifthe problem sites are all in the same geographic area, it is unlikely thata BTS equipment problem exists. GPS alarms at multiple sites are agood indicator of GPS Interference.

4.1.2. Fix Faulty HardwareIf no interference is detected, proceed with vendor recommendedtroubleshooting procedures to locate and correct the problem with theBTS.

4.1.3. Inform Management Team of the Situation

Inform the local RF Manger that interference is suspected in yourmarket. The local RF Manager will keep Core RF Interference

Interference Identification and Mitigation 5. Defining Interference


Management informed of the situation. Proceed with interferencedetection and mitigation procedure.

5. Defining InterferenceInterference is the reception or any signal other than the one that isintended. It can be natural, man made, or a combination of both. It isoften frequency, geographic and/or time dependant.

Unintentional and unexpected RF sources of interference can occurwith surprising frequency and can completely disrupt a communicationlink. Some examples of unintentional sources include computers,microwave ovens, UPS units, power switches, vehicles, and florescentlights. The best way to prevent interference from these sources is toremove them from the area.

Intentional RF interference sources fall into two categories, Local andTerrestrial.

Local RF transmitters include but are not limited to cellular phones,cordless phones, AM radios, FM radios, studio transmitter links, pagingsystems, airport radar and amateur radio transmitters. These sources areusually not the same frequency as PCS systems but can cause problemsat high power levels or harmonic frequencies.

Terrestrial and airborne RF interference sources can include cellulartransmit towers, microwave links, airport radar, airplane radar, marineradar and military electronics. These sources can cause significantproblems for PCS band transmissions and reception. This type ofinterference is characterized by strong signal strength with intermittentbrief signal dropouts.



PCS Spectrum Blocks

To aid in finding interference a PCS Spectrum allocation chart has beenincluded for reference. It is important to know which block andchannel(s) you are operating in before hunting for an interferer.

1200 Channels spaced 50KHz apart on each of Forward and Reverse LinkCompute Channel Numbers and Frequencies

TransmitterEnter ChanNumber

ResultingFreq (MHz)

EnterFreq (MHz)

ResultingChan No. Channel #

CenterFreq MHz

Mobile 25 1851.25 1851.25 25 0 <= N <= 1199 1850.000 + 0.050N

Base 25 1931.25 1931.25 25 0 <= N <= 1199 1930.000 + 0.050N

A D B E F CReverse(Uplink)

LinkTransmit

1850 1865 1870 1885 1890 1895 1910

15MHz 5MHz 15MHz 5MHz 5MHz 15MHz

1930 1945 1950 1965 1970 1975 1990

A D B E F CForward

(Downlink)Link

Transmit

Figure 5-1: PCS Channel and Block Allocations

BTA/MTA/License holders can be found on the following web site:

http://wireless.fcc.gov/services/broadbandpcs/

5.1. Isolate Approximate Area of InterferenceFrom Performance Statistics

When an area experiences interference, it typically affects sites closestto the source of the interference first. Sites that are located farther awaysuffer less performance degradation. By reviewing current cellperformance an approximate location can be determined for theinterferer. If the cause is uplink or downlink typically onlyblock/drop/TCCF/origination counts will be affected. If a group of cells

http://wireless.fcc.gov/services/broadbandpcs/



lose GPS sync, GPS interference could be the cause and should beinvestigated. Use this information to help narrow the search area/band.Interference can also happen inside large venues and facilities. Thistype of interference may not impact clusters of cells but individualserving cells or sectors. Interference may only affect a single carrier orit may affect multiple carriers. Different interference sources will havedifferent areas of impact and this should be taken into account wheninvestigating. There may also be multiple interferers, in which casestart with the strongest one and mitigate one at a time and tackle themone by one.

Symptoms of uplink band interference:

• Cell drop rates increase over a large area

• Cell block rates increase over a large area

• Attempt rates decrease over a large area

Symptoms of downlink band interference:

• Cell drop rate increases but area is more confined then uplinkinterference

• Cell block rates increase but area is more confined then uplinkinterference

• Call performance is ok in well covered areas but degrades in weakerareas

• Attempt rate unaffected, TCCF rate high.

Symptoms of GPS interference:

• Group of cells experiencing sync/timing issues

5.2. RF Engineering Proceeds to Area andInvestigates Cause

Once a rough area has been determined, RF Engineering will proceedto the area equipped with a mobile handset, spectrum analyzer, and adirectional antenna. If you are unfamiliar with Spectrum Analyzer



operation refer to the appropriate user manual. If a spectrum analyzer isnot available a drive test unit equipped with a spectrum analyzer optioncan be a good substitute.

Before using the spectrum analyzer to find the interferer you should usea mobile phone to narrow the area search area. Begin making test calls.When you get to areas that you have origination/termination/dropproblems you should then begin using the spectrum analyzer. If you tryto identify the interferer in areas where call processing is unaffectedyou may not find the inteferer and waste valuable time looking. Themobile is a great tool in narrowing the search area.

A Sprint PCS phone set to Analog roaming mode should be used whenoperating in areas that are suffering performance issues frominterference when communications to and from management/RFengineering are required.

Once you are located in an area of poor call processing connect aspectrum analyzer to a nearby BTS’ RX test port or receive diversityantenna to aid in searching for the source of interference. A portabledirectional antenna such as a small Yagi or panel antenna can also yieldgood results. Ideally you should be above the local surrounding clutter,as this will reduce the likelihood of receive multipath. If takingmeasurements from a rooftop repeat the measurements a couple oftimes from different points separated by several yards to overcome anypotential multipath fading. The majority of readings should have thesame direction or azimuth however it is possible to have multiplesources in different directions. It is also entirely possible to make thesemeasurements in building. Interference can happen and is common inplaces like airports and convention centers.

CAUTION: Accidental connections of test gear to a BTS transmitport can cause permanent equipment damage.

5.3. Identify Interference Type

5.3.1. Search Uplink Band for Interference

The search should begin with the uplink frequency band. Set up theequipment to observe your uplink band. Reference Figure 5-1 forchannel assignments. Look for any signal that should not normally be



found in the uplink band. A typical CDMA uplink band should appearto have no signal and a low noise floor, -110dBm. This holds true evenat the base station. A CDMA carrier, commonly referred to as a Barthead (Bart Simpson), will only be seen if a mobile is in close proximityto the test antenna. Normally this is not the case. You may need to panthe antenna and use different polarization to best see the interferer.Watch the band for a few minutes. The interferer may be intermittent orhave a low duty cycle. Be patient. If you do not see any interference inthe uplink proceed to testing the downlink frequencies. If an interfereris identified move on to triangulating it’s position. Test gear set up indata logging mode can also prove helpful in tracking intermittentinterference. Logs may indicate patterns that can be used to pinpointinterference locations.

Figure 5-2: Normal Uplink Band with no Nearby Mobiles

Figure 5-2 shows a normal uplink band. Signals in the band arenormally at or near the noise floor. Note the lack of any strong carriersor other signals, this is normal.



Figure 5-3: Normal Uplink Band with a local F1 Mobile in Call

Figure 5-3 shows a normal uplink band with a mobile in conversationmode 5 feet from the antenna. This is not the normal case but you mayobserve a Bart head when nearby mobiles transmit. It is notinterference.

1850 1860

-110dB

-55dB

Figure 5-4: Representation of Uplink Band Interference



Figure 5-4 represents actual uplink interference generated by a USNavy vessel in San Diego harbor. Normally the uplink band is at ornear the noise floor with no visible carriers. This signal was so strongnearby mobiles transmitting could barely be seen over the Navy signal.Not all uplink interference will be this easy to identify.

5.3.2. Search Downlink Band for InterferenceIf no interference is observed in the uplink band, the downlink bandshould be checked next. Look for any signal that would not normally beseen in the downlink band. A typical CDMA downlink band will have adistinct Bart head for each carrier and each Bart head should beuniform in height and 1.25 MHz wide. Areas between carriers shouldbe at or near the noise floor. It is possible to have an interferer hide inthe Bart head. Panning of the search antenna and changing locationswill help to unmask such an interferer and cause it to rise above theCDMA Bart head. Watch the band for a few minutes. The interferermay be intermittent or have a low duty cycle. If an interferer isidentified you should move on to triangulating its position.

Figure 5-5: Normal CDMA Downlink Carriers

Figure 5-5 shows a normal two-carrier downlink band. It is normal tosee Bart heads in the downlink band. A typical CDMA carrier will havea distinct Bart head for each carrier and each Bart head should be



uniform in height and 1.25 MHz wide. Large spikes protruding from orbeside a Bart head indicate interference. Interference can also be wideband. In this case Io will be adversely effected and the noise floor willbe higher than normal.

1930 1940

-110dB

-100dB

-90dB

-80dB

1935

Figure 5-6: Downlink Band with GSM Carrier Interfering

Figure 5-6 shows a fictional downlink interferer, in this case a 200KHzwide mistuned GSM base radio. This signal could also appear insidethe Bart head.

5.3.3. Search GPS Band for Interference

It is possible to have GPS interference. This will show up as a loss ofsync to a cell or cluster of cells. In the case of an individual cellsuffering sync or timing problems hardware causes should beeliminated first. Look for any signal that should not be in the GPSdownlink band. A typical GPS downlink (1559 – 1610MHz) band willresemble a CDMA downlink band, with little or no visible signal. GPSuses Spread Spectrum technology and resembles the CDMA downlink.Any defined signal should be considered interference. Watch the bandfor a few minutes. The interferer may be intermittent or have a low duty

Interference Identification and Mitigation 6. Location of Interference


cycle. If an interferer is identified you should move on to triangulatingits position.

1559MHz 1610MHz

Figure 5-7: Typical GPS Downlink band.

A typical GPS downlink band will have no clear transmitters present.Anything that is should be considered interference.

5.3.4. Inform Management Team of the SituationInform the local RF Manager of the current situation. Information toreport must include type (Uplink, Downlink or GPS), frequency andbandwidth of the interferer. Local RF Management will keep Core RFInterference Management abreast of the situation.

6. Location of Interference

6.1. Triangulation and Location of theInterference Source.

Triangulation is a process by which the location of a transmittingsource can be determined by measuring either the radial distance, or thedirection, of the received signal from two or three different points.



Triangulation is sometimes used in cellular communications to pinpointthe geographic position of a user or interferer.

The drawing below illustrates the basic principle of triangulation. In thescenario shown, the location of the emitter is determined by measuringthe relative direction of the signal from three different locations. Thearea where the radials overlap becomes the search area for the emitter’slocation.

Figure 6-1: Triangulation Method

6.1.1. Begin TriangulationUse a spectrum analyzer and a directional antenna to locate the sourceof the Interference. Peak the signal coming from the interferer using thedirectional antenna and measure the direction or azimuth of the signalusing a compass.

6.1.2. Map Location of InterfererPlot this as a straight line on a map from the current location,remembering to correct for compass declination.



6.1.3. Repeat Triangulation MeasurementsProceed to a new measurement location, preferably far enough awayfrom the first measurement point to get good triangulation. Repeat theazimuth measurement on the peaked signal. Plot this new line on themap.

6.1.4. Interferer Location TriangulatedRepeat this process at least one more time from another new location.When completed you should have 3 intersecting lines. This is theapproximate location of the interferer within a triangle of uncertainty.

As you get closer to the target area, you may need to repeat thetriangulation measurements. Measurements should be made muchcloser to the triangle of uncertainty then any previous rounds. The firstset of measurements will be a good approximation of the location,while the second and any subsequent rounds will help pinpoint theinterferer’s exact location. This method can also be used to findinterferers inside a large building.

Figure 6-2: Multiple Triangulation Measurements

Once the interferer has been located you can begin the mitigationprocess. Remember that the longer the interferer broadcasts the morenetwork performance is impacted.

Interference Identification and Mitigation 7. Mitigation of Interferer


6.1.5. Inform Management Team of the SituationInform the local RF Manager of the current situation. Information toreport must include location and identity of interferer. Local RFManagement will keep Core RF Interference Management abreast ofthe situation. Sprint PCS phone placed in analog mode will facilitatecommunications in areas of interference.

6.1.6. Interference Location Can Not be IsolatedIn the rare case where the interference source cannot be triangulatedand identified, notification to Core RF Interference Management Groupis mandatory. Core RF has tools available to identify interferencecaused by passive emissions or other hard to detect sources. If thesituation warrants Core RF will dispatch a team to isolate and mitigatethe interference.

7. Mitigation of Interferer

7.1. Negotiate the turn off of interfering source

7.1.1. Visit Interfering Site

RF engineering will visit the location of the interference and negotiateto turn it off. Maintaining a professional approach when dealing with aninterfering agency is a must. In most cases interference is unintentional,however interference impacts the network and the interfering partymust be made aware of this. If the interferer is unwilling to stop theemissions, escalate to Core RF. Do not physically turn off the sourcewithout permission from the source owner. The act of turning off areceiver without permission of the transmitter owner is illegal. Escalateto Core RF if you do not get permission from the owner.

7.1.2. Inform Management Team of the SituationInform the local RF Manager of the current situation. Report the statusof the interferer and state the need for Core RF escalation if required.The local RF Management will keep Core RF Interference Managementabreast of the situation.

Interference Identification and Mitigation 8. After Action Review


7.1.3. Escalate to Core RF ManagementIf the interfering agency or person does not want to cease harmfultransmissions or continues to cause interference, Core RF will benotified and they will escalate to senior management and in some casesthe FCC.

Core RF Interference Management may be reached at 913-890-2519.

8. After Action Review

8.1. Update Management

8.1.1. Inform Management Team of the SituationInform the local RF Manager of the current situation. At this point theinterference should be mitigated or Core RF brought in to find andresolve the issue. The local RF Manager will keep Core RF informed ofthe situation.

8.2. Report Generation an Submission

8.2.1. Local RF Generates an After Action ReviewReportA final After Action Review report will be generated and submitted tothe local RF manager by the local RF team that mitigated the interferer.The format of the report is detailed in Section 9. Required informationincludes:

• RF Engineer(s) involved – RF team members involved in theinterference mitigation

• Event Start time and date

• Event End time and date

• Duration – Duration of the event

• Market(s) – Market(s) impacted



• System(s) – Lucent, Nortel, Motorola, Samsung

• Resulting action items – Action items resulting from theinterference event.

• Description of event – Details of the entire event, Symptoms, Typeof Interference, Location of Interferer, Identity of Interferer, TestEquipment Used, Spectrum Analyzer plots, etc.

• Event high points/low points – What could have been better? Whatwent well?

• Lessons Learned – Improvements to process, etc.

• Impacted cell list – List of cells where performance suffered.

• Performance Impact – Detail network performance degradation.Include all relevant drop/block performance information.

• Recommendations – Detail any recommendations resulting from theevent/process.

• Associated Documents – Any documents that can be associatedwith the event. This includes relevant SSEO documents.

8.2.2. Local RF Forwards AAR Report to San DiegoRF ManagerThe Local RF manager will review the report and submit the report tothe San Diego RF Manager who will use the input to refine andimprove this process. The San Diego RF Manager will forward thereport to the Core RF group.

8.2.3. Core RF circulates AAR reportCore RF will review the report. The After Action Review report willthen be forwarded to all Sprint PCS markets for information andreference.

8.2.4. Core RF Corresponds with Interfering PartyCore RF will generate a letter addressed to the agency involved in theinterference. All available data will be taken from the final report andused to justify Sprint PCS’s stance and advice the interferer to cease



and desist further interference. Core RF will furnish the local RFManager a copy of this letter for reference. In the case where theinterfering agency causes harmful interference a second time Core RFwill have justification to formally report them to the FCC.

Interference Identification and Mitigation 9. After Action Review Reporting Format


9. After Action Review Reporting FormatAFTER ACTION REVIEW SUMMARY – INTERFERENCE

RFEngineer:

ReviewDate:

Date: EventStart:

Event End: Duration:

Market(s): System(s):

Title: SeverityLevel:

Resulting Action Items:Owner Deliverable Est. Delivery

Disclaimer: Information contained within this document is considered reliable based on the information available at thetime of the After Action Review. New information derived from Action item may change the conclusions ofthe AAR.

Description of Event

What was done well?

What could have been done better?

RF ENGINEERING LESSONS LEARNED Type (FYI orWarning)

Impacted Cell List?

Performance Impact Attempts Blocks DropsRegular PeriodImpacted Period

RECOMMENDATIONS OWNER STATUS

ASSOCIATED DOCUMENTS

Figure 9-1: After Action Review Report Format

Interference Identification and Mitigation 10. Approval Page


10. Approval Page

Prepared by:

Terry KolodyRF EngineerSan Diego RF Engineering

858-621-7137

mailto:[email protected]

Michael ErichSenior RF EngineerSan Diego RF Engineering

858-621-7129


Derek YachaninRF Engineering ManagerRF San Diego & Hawaii

858-621-7118


Michael LawsonEngineer

Darryl RomeroRF TechnicianNetwork Operations - Southern California

619-785-5700


Concurred by:





Interference Identification and Mitigation 10. Approval Page


NameTitleDepartment

Approved by:

Name of ManagerTitleDepartment

Name of Director (if applicable)TitleDepartment