100498575 Actix Troubleshooting and Optimizing UMTS Network

Tr ou ble sh oot ing a n d Opt im izin g UM TS N e t w or k Actix Education Services April 2006

All contents of this document are the property of Actix and are provided for information purposes only. The information in this document is subject to change without notice. Actix will not be held liable for technical or editorial omissions made herein, and will not be held liable for incidental, consequential or other similar damages resulting from the use of its products. Copyright © Actix 2006. All Rights Reserved

Troubleshooting and Optimizing UMTS Network Workshop

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Con t e n t s INTRODUCTION ........................................................................................................................................ 5 SCOPE OF THE COURSE ................................................................................................................................. 5 WHO SHOULD ATTEND THIS TRAINING COURSE?.......................................................................................... 6 PREREQUISITES ............................................................................................................................................ 6 TOPICS TO BE COVERED ............................................................................................................................... 7 CHAPTER 1.................................................................................................................................................. 9 INTRODUCTION TO NETWORK DEPLOYMENT ............................................................................................... 9 CHAPTER 2................................................................................................................................................ 11 SCANNER THRESHOLDS, PREFERENCE & ATTRIBUTES .............................................................................. 11 UE THRESHOLDS, PREFERENCE & ATTRIBUTES ........................................................................................ 15 ATTRIBUTES .............................................................................................................................................. 23 EXERCISE 1: EXAM YOUR OWN DATA (ATTRIBUTES) ............................................................................... 31 CHAPTER 3................................................................................................................................................ 32 SITE AND CLUSTER INTEGRATION ............................................................................................................. 32 INTEGRATION PRE-REQUISITES ................................................................................................................. 33 CHAPTER 4................................................................................................................................................ 36 SITE INTEGRATION .................................................................................................................................... 36 POST PROCESSING AND ANALYSIS USING ACTIX SOFTWARE .................................................................... 38 EXAMPLE: HOW TO DETERMINE HARDWARE PROBLEM OR CROSSFEEDER DURING SITE INTEGRATION? . 39 EXERCISE 2: SITE INTEGRATION ................................................................................................................ 46 CHAPTER 5................................................................................................................................................ 47 CLUSTER INTEGRATION ............................................................................................................................. 47 FIRST DRIVE TEST: SC SCAN AND DEDICATED MODE ................................................................................ 49 IMPORTANT CRITERIA FOR CLUSTER INTEGRATION .................................................................................. 52 MISSING NEIGHBOURS ............................................................................................................................... 58 MISSING NEIGHBOURS ATTRIBUTES .......................................................................................................... 69 SCANNER BASED NETWORK ROLLOUT ANALYSES: NEIGHBOUR LIST ANALYSIS ..................................... 71 INTERFERENCE FACTOR (F FACTOR) ......................................................................................................... 74 F FACTOR REPORT ..................................................................................................................................... 77 EXAMPLE: COVERAGE ANALYSIS .............................................................................................................. 78 EXAMPLE: CPICH POLLUTION ANALYSIS ................................................................................................. 80 SECOND DRIVE TEST: DEDICATED MODE WITH SC SCANNING ................................................................. 83 TYPES OF DROPS (RADIO AND NON-RADIO RELATED):............................................................................. 86 EXAMPLE: DROPPED CALL ANALYSIS ....................................................................................................... 89 EXAMPLE: CALL SETUP FAILURE ANALYSIS ............................................................................................. 91 EXIT CRITERION DRIVE TEST .................................................................................................................... 93 EXERCISE 3: CLUSTER INTEGRATION ......................................................................................................... 96 SITE INTEGRATION IN INTEGRATED CLUSTER............................................................................................. 97 CHAPTER 6................................................................................................................................................ 98 CELL RESELECTION ................................................................................................................................... 98 RESELECTION CRITERIA ............................................................................................................................ 99 MEASUREMENT RULES ............................................................................................................................ 100 INTRA FREQUENCY SOFT HANDOVER ...................................................................................................... 101 HANDOVER ATTRIBUTES AND RELATED EVENTS .................................................................................... 105


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HANDOFF ANALYSIS................................................................................................................................ 108 EXERCISE 4: HANDOVER ......................................................................................................................... 111 CHAPTER 7.............................................................................................................................................. 112 REPORT.................................................................................................................................................... 112 EXERCISE 5: SINGLE FILE REPORT TEMPLATE ......................................................................................... 113 WHERE TO GET MORE HELP............................................................................................................ 116 HELP FILE ................................................................................................................................................ 116 TECHNICAL SUPPORT............................................................................................................................... 118 APPENDIX A UMTS EVENT DEFINITIONS .................................................................................. 119


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Introduction Scope of the course Troubleshooting and Optimizing UMTS Network workshop provides a comprehensive overview of the integration and radio optimisation procedure for WCDMA networks making use of the Actix Analyzer. Our goal is to give new users an understanding of what Analyzer can do and how it can help them improve the quality of service for their network subscribers. Advanced users will be introduced to Analyzer features they may not know about and to new network applications that can be performed using Analyzer. The instructors for this course are experts in optimising 3G networks and are familiar with the challenges faced by engineers using measurement and postprocessing software.

Class size is limited to ensure that everyone receives extensive one on one instruction. Participants are given ample opportunity to ask questions relevant to their particular optimization needs. Upon completing the course, participants will be able to use what they learned in class to identify and solve real network problems.

Troubleshooting and Optimizing UMTS Network workshop begins with a highlevel presentation of the Analyzer interface and its capabilities. We will then cover how Analyzer can be customized to tailor existing optimization processes to the specific needs of the participants. We will try to establish procedures and create Analyzer customized solutions for these procedures


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Who should attend this training course? Engineers responsible for enhancing cellular performance and implementing wireless system optimization. System Performance Engineers responsible for measuring and quantifying network quality relative to competitors and/or established benchmarks. Engineers looking to further understand the application of drive test, call trace and protocol data in optimizing networks. Experienced technicians involved in field optimization. Anyone looking to maximize the return on investment in Actix software.

Prerequisites Familiarity with network infrastructure and operation of the air interface. A general understanding of drive test and call trace collection and post-processing methodology and advantages/limitations with each dataset. Access to Actix software. Basic computer literacy, including familiarity with Windows and MS Office applications.


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A computer meeting optimal (or at least minimum) requirements: Hardware

Optimal Performance

Minimal Performance

Processor:

P4 2.6 GHz

Pentium II 440 MHz

1 GB

256 MB

60+ GB Available

1 GB Available

1280x1024 64k colour resolution

1024x768 256 colour resolution

Memory (RAM) Disk Space Monitor CD-ROM drive One parallel port

To install the application For single-use hardware key

Mouse and keyboard

Yes

In addition to the hardware requirements listed above, the Actix platform performs best when the Windows Virtual Memory Paging size is set to between 1000 and 1500 MB. The method for setting this parameter varies by operating system. Please consult your OS help for specific instructions regarding this parameter.

Topics to be covered Configuring your workspace, including map, cell site, and parameter configuration in order to display your geographic area and network cell plan. Viewing data in a variety of ways to gain insight into possible network problems. Diagnosing and solving quality of service problems with drive test and switch data. Using pre-defined and custom analyses to analyze data and devise tailored optimization solutions.


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Identifying the impact of wide area network optimization changes in terms of Quality of Service, using advanced features to develop optimization process and procedures. Using some of the latest engineering processes, which highlight how to fine tune network performance and further enhance quality of service. Using the Help options and maximizing the benefit of technical support.


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Chapter 1 Introduction to Network Deployment The common practice for Network Deployment is shown below:

Service Definition and QoS Requirements

Link budget establishment and Nominal design

Deployment activities (site acquisition, civil works, installation etc)

Design Validation

Site and Cluster Integration

KPI Definition and Tracking

Ongoing optimization

= Ongoing Optimization of Growing and mature network


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Network Design Validation Design validation is executed on the first cluster(s) of a new area where 3G is deployed. The aim of the validation is to approve the link budget and eventually to change or update that link budget with some radio engineering measurement quantities which can be typical for a certain region.

Site Integration Site integration is performed to test how well Node B is functioning, hardware (e.g. installation of aerials and cabling), and software (e.g. correct parameters downloaded and connection with RNC functions). A drive test can be conducted where scanner and trace mobile are used to verify if node B is functioning well.

Cluster Integration Cluster integration is performed to maximize the coverage in the cluster with the available sites. When performing on an unloaded network, cluster integration is coverage based. After the initial tuning (cluster integration), ongoing optimization tasks, such as Dedicated Drive Test (dedicated mode with SC scanning) will be performed. The network deployment activities will deal with real traffic KPI s, and trouble tickets will be raised if necessary.

Ongoing Optimization The ongoing optimization is performed on the growing and mature network to assure best quality of the network. Tracking and defining the optimum KPIs will be the key tasks in fine tuning and optimizing the network. If a new site or cluster is required, the site and cluster integration phases will be repeated.


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Chapter 2 Scanner Thresholds, Preference & Attributes Thresholds are user-definable values that can be used as constants in event detection and queries. For example: Uu_Scan_Poor_RSCP_Threshold defines the minimum value which the RSCP signal is considered to be poor. This threshold has a default value of -95 dBm, but users can change this to any other value. Using a threshold (rather than a hard-coded value) in queries and event diagrams makes it is easy to adjust them for individual requirements.

Tools

Display Thresholds

UMTS

Scan_Coverage

Scanner Thresholds Uu_Scan_PilotPollutionThreshold (Scanner Pilot Pollution) Recommended value is -15 dB and value should vary between -10 and -18 dB. By changing this threshold value, it will directly affect the Uu_Scan_PilotPollution attribute. Uu_Scan_TooManyServersThreshold (Scanner Too Many Server Event) Recommended value is 5 dB and value should vary between 1 and 10 dB. By changing this threshold value, it will directly affect the Uu_Scan_TooManyServers attribute.


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Scanner Attributes (Coverage Related Events) Uu_Scan_PilotPollution (Pilot Pollution) Actix Software s event detection allows you to visualize pilot pollution on a map with drive test scanner data. The pilot pollution event occurs when 4 or more pilots with Ec/Io greater than Uu_PilotPollutionThreshold are can be seen.

Uu_Scan_TooManyServer (Too Many Servers) Due to UMTS uses relative levels to evaluate additions/removals to the active set. Actix Software has a different event that allows the engineer to visualize pilot pollution relative to the best server. The Too Many Servers event behaves similarly like the pilot pollution event except with relative levels. The event occurs when 4 or more pilots with Ec/No within Uu_Scan_TooManyServersThreshold dB of the best server (CPICH_Scan_EcIo_SortedBy_EcIo [0]).

Other Information Attributes (Emulated Active Set Module) EventCellAddition EventCellRemoval EcIo_in_ActiveSet EcIo_in_MonitoredSet

CPICH Pollution Analysis and Handoff Analysis are both based on a calculated Active Set, which is determined by the Emulated Active Set module. The Emulated Active Set module implements the 3GPP handoff algorithm and uses scanner Ec/Io measurements in conjunction with user-specific 3GPP handoff thresholds to emulate the Active Set at each point along a drive test.


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A sample set of scanner data for three SCs with individual colour and vertical lines indicating transitions of pilots into and out of the Active Set is shown below:

Using Scanner Ec/Io measurements to implement 3GPP handoff algorithms for the Active Set

Scanner Preferences The WCDMA options within the General Settings group in the Tool Preferences dialog control the simulated active set feature. When this feature is selected, Analyzer calculates a UMTS simulated active set from the scanner data, as it envisages the handset would see it. You can configure the simulated active set and specify the maximum size of the simulated active set in the range 1 8. The simulated active set feature was useful in the early days of WCDMA technology, when logging devices were not readily available. Now that they are available, you may want to turn off the feature.


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Setting 3GPP handoff algorithm attributes including Reporting Range: Hysteresis Event and Time to Trigger Event

The parameters depicted in the picture are based on the WCDMA events defined in the 3GPP TR 25.922 V4.1.0 (2001- 09) Radio Resource Management Strategies specification. Max. Active Set Size (up to 8) specifies the maximum size of the Active Set (1-8). Disable active set simulation. Select this check box to turn off the active set simulation feature. This will usually give faster file loading times and will mean that the lines to cells feature in the map will be based on the measured SC (if it's available) rather than the simulated active set. This option is off (deselected) by default.


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UE Thresholds, Preference & Attributes UE Thresholds

Tools

Display Thresholds

UMTS

UE_Coverage

Uu_EcNoInterferenceThreshold (System Interference) Recommended value is -15 dB and value should vary between -10 and -18 dB. Uu_RSCP_InterferenceThreshold (System Interference) Recommended value is -80 dBm and value should vary between -60 and -90 dBm Uu_Poor_EcNoThreshold (Coverage Limited, Poor Downlink and Poor Uplink Coverage) Recommended value is -15 dB and value should vary between -10 and -18 dB Uu_Poor_RSCP_Threshold (Coverage Limited, Poor Downlink and Poor Uplink Coverage) Recommended value is -95 dBm and value should vary between -85 and -105 dBm Uu_HighUE_TxPower (Poor Uplink Coverage) Recommended value is 15 dBm and value should vary between 0 and 25 dBm Uu_LowUE_TxPower (Poor Downlink Coverage) Recommended value is -15 dBm and value should vary between 0 and -30 dBm Uu_CoverageLimitedUE_TxPowerThreshold (Coverage Limited) Recommended value is 10 dBm and value should vary between 0 and 25 dBm


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Uu_PilotPollutionThreshold (Pilot Pollution) Recommended value is -15 dB and value should vary between -10 and -18 dB Uu_CallSetupFailure_Num_RRCConnReq (Call Setup Failure event) Recommended value is 3 and value should vary between 1 and 5 Uu_CallSetupFailure_TimeDelay (Call Setup Failure event) Recommended value is 2 and value should vary between 1 and 45 seconds Uu_TooManyServersThreshold (Too Many Server event) Recommended value is 5 dB and value should vary between 1 and 10 dB Uu_t309_wait_timer (CellChangeOrderfromUTRAN process) Recommended value is 5000ms (5Sec) and value should vary between 5000 and 10000. Uu_ReEstablishment_wait_timer (Reestablishment process) Recommended value is 0ms and value should vary between 0 and 15000 Note: Zero = disables this feature. Uu_wait_timer_complete (Change Reconfig process) Recomended value is 8000ms (8Sec) and value should vary between 0 and 15000 Note: Zero = disables this feature.


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UE Attributes (Coverage Related Events) Uu_SystemInterference (System Interference) The system interference event occurs when the CPICH_EcNo_in_ActiveSet is less than Uu_EcNoInterferenceThreshold (in dB) and the CPICH_RSCP_in_ActiveSet is greater than Uu_RSCP_InterferenceThreshold (in dBm).

Example of system interference before a dropped call

Uu_PoorUL_Coverage (Poor Uplink Coverage) The poor uplink coverage event occurs when the CPICH_EcNo_in_ActiveSet is greater than Uu_Poor_EcNoThreshold and the CPICH_RSCP_in_ActiveSet is greater than Uu_Poor_RSCP_Threshold and UeTransmittedPower is greater than Uu_HighUE_TxPower threshold.

Example of poor uplink coverage before a dropped call


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Uu_PoorDL_Coverage (Poor Downlink Coverage) The poor downlink coverage event occurs when the CPICH_EcNo_in_ActiveSet is less than Uu_Poor_EcNoThreshold and the CPICH_RSCP_in_ActiveSet is less than Uu_Poor_RSCP_Threshold and the UeTransmittedPower is less than Uu_LowUE_TxPower threshold.

Example of poor downlink coverage before a dropped call

Uu_CoverageLimited (Coverage Limited) The coverage limited event occurs when the CPICH_EcNo_in_ActiveSet is less than Uu_Poor_EcNoThreshold and the CPICH_RSCP_in_ActiveSet is less than Uu_Poor_RSCP_Threshold and the UeTransmittedPower is greater than Uu_CoverageLimitedUE_TxPowerThreshold.

Example of coverage limited problem before a dropped call


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Uu_PilotPollution (Pilot Pollution) Actix Software s event detection allows you to visualize pilot pollution on a map with drive test data. The pilot pollution event occurs when 4 or more pilots with Ec/No greater than Uu_PilotPollutionThreshold are in the active or monitored set. Look at each SC and try to find out what is the best way to optimize the area. See the training document for a full detailed description on optimization techniques.

Example of pilot pollution before a dropped call


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Uu_TooManyServer (Too Many Servers) Due to UMTS uses relative levels to evaluate additions/removals to the active set, RVS has a different event that allows the engineer to visualize pilot pollution relative to the best server. The Too Many Servers event acts like the pilot pollution event except with relative levels. The event occurs when 4 or more pilots with Ec/No within Uu_TooManyServersThreshold dB of the best server (Uu_ActiveSet_EcNo_0) are in the active or monitored set. Look at each SC and try to find out what is the best way to optimize the area. See the training document for a full detailed description on optimization techniques.

Example of too many servers around a dropped call


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UE Attributes (System Related Events) Uu_HandoverProblem (Handover Problems) Actix Software s event detection allows you to visualize handover problems on a map with drive test data. The handover problem event works as follows: o Event detection looks for a dropped call or call setup failure o It counts the number of times when the first best SC in the Monitored set is stronger than the first best SC in the Active set, within an 8-second window leading up to the drop. o If that number is greater than the number of times the Active set is stronger than the Monitored set, it sets a Handover problem (assuming we have no Active set update messages)

Example of handover problems before a dropped call


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Uu_MissingNeighbour (Missing Neighbours) Actix Software s event detection allows you to visualize missing neighbour on a map with drive test data. The missing neighbour event occurs when a particular SC is not in the neighbour list and forces the call to drop. The following procedure is followed to trigger the event: o When the drop call occurs, a specific function looks for the next origination and gets the value of the new SC in the active set. If the new SC is different from the SC s in the active set before the call dropped, the function looks for the last neighbour list before the call dropped. If that same neighbour list does not contain the new SC, it is a possible missing neighbour.

o

o

So, in other words: If (SC in active set after drop call) <> (SC s in active set before drop call and Neighbour list before drop call) then missing neighbour Of course, in this case, the engineer needs to understand the coverage issues. If the new SC is not meant to cover the specific area, optimization is probably the best solution and the engineer should not add the specific neighbour.

Example of missing neighbour before a dropped call


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Attributes It is important to differentiate between the scanner and UE attributes. Upon loading a UMTS data file, several data groups are created for each device contained in the file.

The UE (Samsung Mobile in above example) provides real measured values, while the scanner (Agilent in above example) provides measurements from all scanned SCs. The active and monitored set information in the following example are simulated, based on thresholds which are set in the Tools preferences. Different UE s provides different Attributes. Some provides trace mobiles log data such as BLER, but others don t. The presented attributes under the UE group are the ones provided by the UE manufacturer. Note that the UE call trace attributes sometimes do not contain what you expect. For example: The Samsung mobile gives attributes on monitored, detected and active set count. These are not totally correct by just taken from the amount of measurements in the uplink measurement report.


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Example Example below shows that measurements obtained from an uplink measurement report might not be always correct. A measurement report gives measurement information on all detected SC of the combined neighbour list. Screenshot below shows that the attribute is not giving the expected data. On the measurement point the active set count is 6 (impossible).

The following tips should be considered when measuring the network: Always use the same trace mobiles Make sure all attributes you use contain the information you want Filter out the non-diagnostic attributes or attributes which are meaningless to you


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UMTS Handset Data Groups in Actix Software Upon loading a UMTS handset file, note that several data groups are created. These data groups are common in Analyzer to all UMTS handset files, regardless of data collection vendor. Each group will appear as long as at least one parameter within that group was collected by the device. The following data groups are created under the UMTS node:

Downlink Measurements This group contains Uu interface measurements reported by the mobile.

Pilot Measurements This group contains signal strength measurements for individual SCs detected within the logfile.

Dedicated Radio Link Once a call has been established, parameters that are associated with the SCs serving the call, such as Handoff State, are contained here.


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Uu_RRC Radio Resource Control is the protocol layer governing air interface communication within the UMTS network. Parameters associated with protocol messaging can be found in this group. Event Data Call events triggered by the current state of the UMTS mobile. If an event is not present in the tree, it did not occur in the file. This group also contains events with user-definable thresholds, such as Uu_PilotPollution and Uu_CoverageLimited. Statistics Data This group contains statistics calculated based on UMTS protocol messaging, including Call Duration and timing components of Call Setup Time. Vendor Specific This group contains parameters unique to a specific type of data collection equipment. Rake Finger Measurements This group (Qualcomm chipset handsets only) provides individual finger measurements, including multipath measurements for the same SC.


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UMTS Scanner Data Groups in Actix Software Due to the nature of the coding scheme in a UMTS system, scanner data is an invaluable tool for detecting problems in the network. Because SCs are reused across a UMTS network with a much lower frequency than in an FDMA/TDMA network, each SC scan can be directly linked to a particular site or sector in the network. The following data groups are created under the scanner stream:

Other This group contains scanner measurements concerning RSSI, Chip Offset, Carrier Error and the Scan Code Group.

Nth Best This node contains ranked measurements for EcNo, RSCP, SC and PathLoss. Within each group, the 0 element contains the best performing data. For example, CPICH_Scan_EcIo_SortedBy_EcNo_0 gives the strongest EcNo of all SCs scanned.

Ec/Io This group contains the interferenceto-chip-energy measurements organized by various dimensions.

RSCP This group contains the Received Signal Code Power organized by various dimensions.

Delay Find the CPICH Scan Delay Spread for each SC in this group.


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Pilot Measurements Find the CPICH PathLoss for each SC in this group.

Active Set This group contains simulated Active Set measurements based on scanner data and the user-defined WCDMA settings in the Tools Preferences dialog.

Monitored Set This group contains simulated Monitored Set measurements based on scanner data and the user-defined WCDMA settings in the Tools Preferences dialog.

Event Data Events in this group are based on the simulated Active Set and Monitored Set SCs based on scanner data and user defined thresholds set under WCDMA in the Tools Preferences dialog.


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Technology- Independent Data Under the Independent folder, you may find some technology independent parameters decoded in Actix Software such as GPS measurements, devicespecific data, and internal Analyzer messages:

GPS Data This group contains mobile longitude, latitude, distance traveled, and speed.

Message Info The date and time for the start of the data stream can be found in this group. This information is useful when building report templates.

Site Data Node If a cell site database is being used in the Analyzer, the software will automatically calculate these measurements that take both the drive and the cell site information into account. Some of the measurements contained here are: ServingCellDistance Distance (in meters) to the serving sector NeighborCellDistance Distance(in meters), to non-primary serving sectors


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File Info In this node find label and timestamp information for the logfile under investigation.

Device Info This group contains settings for the mobile device on which data is logged.

Vendor Specific Vendor Specific measurements may be grouped here or under the UMTS node. In either case, this group provides measurements specific to the particular collection device used.


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Exercise 1: Exam Your Own Data (Attributes) Exam these attributes from your UE and scanner logfiles by displaying them on a map, tables or charts:

Exam the attributes from the UE and scanner Find out the interaction between the values under tab Nth best and Ec/Io


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Chapter 3

Site and Cluster Integration This chapter explains what the radio engineering tasks are and the tests to be performed during site and cluster integration. This includes the phase between site commissioning and site for commercial use. This RF intervention (initial tuning and optimization) happens after the design part and before the ongoing optimization phase:

Detailed Radio Design using Planning Tool Software

Initial Tuning and Optimization: Site and Cluster I ntegration

Performance Engineering and Ongoing Optimization

Site Integration Site integration is performed to test the well functioning of the Node B, hardware (e.g. installation of aerials and cabling), and software (e.g. correct parameters downloaded, connection with RNC functioning). Cluster Integration Cluster integration is performed to maximize the coverage in the cluster with the available sites. Cluster integration is coverage based and as such it is performed in an unloaded network. After cluster integration (initial tuning), ongoing optimization tasks will be performed. These actions are based upon (real) traffic KPI s and eventually trouble tickets. If a new site is needed, the steps in site integration will be repeated.


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Integration Pre- Requisites Before you start to integrate a site or/and a cluster, the following roll-out procedure should be performed and make sure the site and integration information documentation is available. This section elaborates how a site and cluster is integrated (from the beginning to the end of roll-out process). It also defines the integration pre-requisites and how the integration is triggered or performed.

1. Roll- out Procedure The following definitions and requirements should be taken into account in the roll-out procedure:

a) Cluster definition Cluster definition is performed at the stage of network design and according to the rules and thresholds coming from the link budget analysis. In general clusters will contain between 15 and 20 sites.

b) Radio Site definition This step is taken place before the site construction begins. The radio engineer will define the initial site configuration and decide on the followings: Node B type Sector definition Antenna type per sector Azimuths and tilts per sector Initial CPICH power setting Antenna heights and cable lengths Additional radio equipment (boosters, MHA, combiners, etc) The site will be constructed and implemented according to these definitions. It is important to keep track of this information and check the integrated site against these site definitions.


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c) Data build The RF part of the data build can be prepared just after the installation and measurement of the radio chain of the site. In this stage the following data needs to be prepared for each cell: Scrambling Code (from planning tool ) Cell Id (from local rule) Local Cell Id (can be equal to Cell Id) SAC (service area code) (can be equal to Cell Id) LAC (location area code) RAC (routing area code) CPICH power (set to 30dBm at TMA level per default) Cable loss (from installation measurements)

2. Site and Cluster Integration Information Documents Before you start to integrate a site and cluster, the following documentation should be available on the cluster: a) Simulation results on final design of the cluster (all sites in nominal plan): CPICH RSCP CPICH Ec/Io Pilot Pollution Overlap b) Simulation results on detailed design: CPICH RSCP CPICH Ec/Io Pilot Pollution Overlap c) Simulation results on individual sites: CPICH RSCP d) Initial 3G-3G neighbour plan: performed in planning tool according to local neighbour planning guidelines At this point, the design will be pre-optimized for coverage. It is clear that the design will not completely fulfill the coverage objectives of the cluster if not all planned sites are ready for integration. These simulations will help you (RF engineer) to detect trouble areas in the cluster where you should be focus on during cluster integration.


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Trigger for site integration The trigger for site integration can be given site per site after installation. Site integration process, as described further in this training course will lead to cluster integration. Trigger for cluster integration The trigger for cluster integration is given on a per cluster basis. Cluster integration can start when all sites in cluster for which detailed design is performed which have had a successful site integration. Any site reaching the status of ready to build , but not previously included in the frozen detailed design, will only be considered in a later phase when it is decided to retune the cluster (see later).


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Chapter 4 Site Integration Purpose of Drive Test When a single site or a new site is integrated, it is important to complete the I&C tests (on-line commissioning tests mainly). This verification shall be done by performing some drive tests around each site clockwise and anti-clockwise at 25-35 percent of the expected cell range (50m 100m in build up area). A scanner and a trace mobile are used to verify if Node B is functioning well.

Drive Tests

Traces are collected from the scanner and the mobiles using any measurement data collection tool. First analysis is done live on the measurement trace tool. Post processing is done with Analyzer by an optimization engineer. The purpose of the site verification is NOT to propose optimization changes for the aerial system or to propose new parameter settings. At this stage, the neighbour planning is not complete and the cluster is not completely build.


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Site I ntegration Procedure

A) Node B installation check The purpose of Node B Installation check is to ensure the Node B is installed and integrated correctly. The focus will be on the following points: Node B up and running; NO ALARMS Feeders connected correctly Antenna clearance OK B) Drive test procedure Choose position in the middle of cell 1 (main beam of antenna) at max 100m (in car or outdoor). Start up UE and scanner logging tool and start logfile Setup CS voice call or CS video call to test number Go (drive) to middle of cell 2, clockwise and check: o SHO functionality (link addition and link removal) o CPICH RSCP (should be > -70 dBm when outdoor; in the middle of the main beam of the antenna; and line of site. o UE TX pwr (should remain below 0 dBm all the time when outdoor, ) o Cell ID (should be the planned one for the SC Terminate CS call and setup new call Go to cell 3 and verify identical parameters Stop and restart CS call and go to cell 1 while checking the same parameters Redo the procedure counter clockwise but with continuous call Setup PS call (ftp download of 10 Mb file) and drive clockwise route


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Post Processing and Analysis Using Actix Software With all the information gathered during the drive test, we can now using Actix Software to analyze the following information to determine if any hardware problem or installation issues occur: SHO functionality (RL addition and deletion in both directions) Call setup on each cell Normal output power behaviour (roughly) Crossed feeders (through SC) and correct identifier parameters (Cell ID) Antenna orientation PS throughput MHA functionality The following information mentioned above can be obtained by examining and analyzing the attributes using Actix Software. 1. All Radio Information (RF Condition) Active Set RSCP (Scanner and UE) EcIo (Scanner and UE) UE TxPower 2. Call Event CS Event PS Event 3 . MHA Malfunction Conclude if Malfunction is due to high UL Tx Power 4. Site Integration Report If all the attributes is OK, the site is considered verified and can be included in the cluster optimization phase. Follow by that, a site integration report should be created with the following information: Test result summary Coverage plots of each cell Parameter summary


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Example: How to Determine Hardware Problem or Crossfeeder During Site Integration? The following example demonstrates how to determine hardware problem or crossfeeder during site integration. After taking the measurements from a site integration drive test, the optimization engineer will check the measured data for the following conditions:

1. RF Condition a) Active Set

By examining the Active Set attributes, you can find out the answers of the following questions: Are the correct Scrambling codes implemented on each cell compared with the data fill values? Are all intra-site SHO working, i.e. active set updates in both directions: addition and deletion?

Screen Layout of Active Set (UE and Scanner) and Tx Power


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Good Practice: Screen layouts are very useful to have an immediate view of how well a site is functioning. The screen shots from previous page shows: Information to look for

Attribute

Site environment & parameter

Display new map to view all available sites

Active set size, simulated from scanner

Uu_SimulatedActiveSet_EcIo_0; Uu_SimulatedActiveSet_Count (if you want to know the count)

Active set size from UE

Uu_ActiveSet_EcN0

UL Tx power

UE_TxPow

b) RSCP (scanner/mobile) for all SC of Node B

By displaying the Serving SC information (from UE and Scanner) on maps, you can quickly determine if any cross feeder (where dominant SC not in its supposed best server area) occurs. By displaying the EcIo and RSCP information from scanner, you ll obtain an overview of the quality and coverage of your network.

Screen Layout of RSCP and EcIo of UE and Scanner


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The screenshot from the previous page shows: Information to look for

Attribute

Serving SC from UE

Uu_ActiveSet_SC_0

Best SC from Scanner

CPICH_Scan_RSCP_For_SC_xxx

Best EcIo from scanner

CPICH_Scan_EcIo_SortedBy_EcIo_0

Best RSCP from scanner

CPICH_Scan_RSCP_SortedBy_EcIo_0

Things to be considered: Is the CPICH RSCP a normal value? Should it be better than -70 dBm, close to the site (< 150m) and outdoor? Is the CPICH Ec/Io a normal value? Should it be better than -8 dB, close to the site (< 150m) and outdoor?

c) Ec/Io (scanner/mobile) for all SC of Node

By displaying the EcIo information from UE and scanner, you ll obtain an overview of the quality of your network. (See example above). Thing to be considered: Is the CPICH Ec/Io a normal value? Should it be better than -8 dB if it is close to the site (< 150m) and outdoor?

d) UE TX power

By displaying the UE TxPower information on a map, it will quickly and easily detect any hardware or installation issue on the downlink path (from Power Amplifier to antenna positioning). The view immediately shows that there are problems with this site. Thing to be considered: Is the UE Tx Power a normal value? Should it be less than 0 dBm if it is close to the site (< 150m) and outdoor. Note: If there are some points above 0 dBm, it may be a mobile issue or an issue on the Uplink path.


41

2. Call events

By displaying the Call Events attributes, such as outgoing call, drop call, and call setup failures, you can obtain the following information: Call Setup Status PS Throughput CrossFeeder

If issues occur, it is possibly come from the Node B (hardware) or from the CS core side. Information to look for

Attribute

Serving SC from UE

Uu_ActiveSet_SC_0

Out Going Call OK

Uu_OutgoingCall_OK

Call Setup Failure

Uu_CallSetup_Failure

Drop Calls

Uu_CallDropped


42

a) Can we setup a CS call on all cells?

To check if a call was successfully done on each sector and soft handover from one sector to another one was good, this is done using the message logging information, checking if call setup and active set update were successful in CS and in PS.

b) PS throughput

Do we have a normal throughput under good radio conditions and low load? Is it better than 90% of maximum RAB (currently 90% of 384 kbps is 350 kbps)? Any throughput that is lower than this may come from issues on mobile / laptop configuration, or issues on the PS side.

c) Crossed feeders

A typical problem that can be, and must be detected at this stage is the crossedfeeder problem. A SC (scrambling code) plot with the designated SC per cell indicated on the antenna is sufficient to detect the problem.


43

3. MHA malfunction A MHA (TMA) malfunction will cause a very high uplink UE Tx Pwr on one cell. If the high TX power occurs on all cells of a Node B, it is more likely the Digital radio modulation (CE) unit has a malfunction. In the example below you can see this last phenomenon. A simple verification on the UL and DL coupling loss gives you an indication of the correctly applied UL Tx Pwr: Formulae: Coupling Loss Downlink (CL DL) CL DL = CPICH Tx Pwr at AE (30 dBm)

CPICH RSCP

Coupling Loss Uplink (CL UL) CL UL = UE Tx Pwr sensitivity at MHA input in unloaded condition (± -120 dBm) If

|CL UL

CL DL| > 8dB

For most measurement points over the service area of the cell, the MHA functionality needs to be checked. This criteria can be checked with the Analyzer tool.


44

Example The map below shows you the result of UE TxPower = 0 based on the criteria mentioned in the previous page. This means there is no problem.

4. Site Integration Report If all these parameters are OK, the site is considered as verified and can be included in the cluster optimization phase. Followed by that, a site integration report should be generated. The report should contain the following information: Test result summary Coverage plots of each cell Parameter summary


45

Exercise 2 : Site Integration Exam your own data Load you own logfile Define views you want to see and create a screen layout. Make report on and save as report template if necessary.


46

Chapter 5 Cluster Integration Procedure


47

Drive test definition Due to the unique nature of each cluster that is defined, it is not possible to put a strict definition on how to plan the drive test route. However, some useful guidelines can be considered as follows:

Soft Handoff Boundaries Because cluster testing is important in optimising the handover boundaries, it is necessary to ensure the drive test route will have the potential to handoff between each cell and each site. Looking at simulation estimations of where soft and softer handoff is predicted can help carry this out. If an RNC boundary falls inside a cluster, this boundary should be taken into account and drive tested intensively.

Weak Coverage Areas It is essential to establish how the air interface performs in areas of predicted weak coverage. Using results gathered from the test measurement equipment will allow the user to establish what causes the weak coverage in a particular area and understand what steps can be taken to improve the situation.

Pilot Non- Dominance Areas The presence of several pilots at a similar level in a particular location can lead to pilot pollution. Areas of pilot pollution can be estimated using the RF planning tool and the person defining the drive test routes can ensure that these areas are tested thoroughly. The scanning receiver will allow the user to measure the received Ec/Io of many pilots (independent of the Ec/Io threshold) and corrective actions can be taken.

High Traffic Areas When carrying out loaded tests, it is imperative that the user includes areas of potential high traffic in the drive test route definition. This will then allow the user to analyse the drive test data and estimate what limitations of the air interface may have in these potentially high traffic areas. For cluster integration purposes only unloaded drive tests will be performed. This unloaded drive test of the tuned radio network will serve as a reference for any drivetest in loaded conditions which can be performed at later stages of the network development. As mentioned, it is necessary for the person defining the drive test routes to carry this task out in conjunction with viewing various simulation plots from the radio-planning tool.


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First Drive Test: SC scan and dedicated mode

Drive Test 1: Unloaded scan test & Dedicated CS


49

The unloaded scan test is intended to show the basic RF performance in the best-case scenario of the cluster, i.e. when the cells portray a minimal load. A test measurement system (which normally consists of a scanning receiver, location receiver and associated software) is used for this task. Analyzing the results on the downlink is straightforward using the software supplied with the measurement system and at this stage the only needed information. We run in parallel with the scanner a UE in dedicated mode (CS 64 videophony, because this is the most limiting service in uplink) in order to detect missing neighbours at this stage. UE and scanner are connected to external (outdoor) antennas. The basic RF performance mentioned above includes: Identification of Coverage Holes Determining handoff regions and neighbour relations Detecting areas of multiple pilot coverage (pilot pollution) Detecting cell overlap The following radio quality indicators need to be measured and as such be included in the log mask of the measurement equipment: P-CPICH Ec/Io Strongest Pilot P-CPICH Ec/Io for best N pilots (above a certain threshold Ec /Io, e.g. 15dB) RSCP RSSI (Io) P-SCH Ec/Io S-SCH Ec/Io Delay Spread The outcome of the drivetest provides he RF engineer the opportunity to check the coverage quality of the CPICH. Based on this check, he/she will be able to decide what to be changed. The changes include: Antenna Type: If the chosen antenna cannot fulfil the coverage objectives of the cell Antenna Azimuth: If the coverage objectives are not met in a certain area or if the cell induces too much interference along a street (canyon effect) Antenna Tilt: If a coverage problem occurs at cell boarder: Below threshold: up tilt Too much above threshold: down tilt


50

Preference is given to adapt electrical tilt above mechanical tilt. Only in special cases mechanical tilt is preferred. The optimization changes should result in an increase of the number of measurement points with good coverage. This good coverage means that the following conditions are fulfilled for the measurement point: Criteria

DU Area

Urban

SU Deep Indoor

SU Indoor Daylight

Best CPICH RSCP >

-82 dBm

-82 dBm

-83 dBm

-90 dBm

Best CPICH Ec/Io >

-8 dB

-8 dB

-8 dB

-8 dB

4 best CPICH RSCP <

Best CPICH RSCP -8dB

Best CPICH RSCP -8dB

best CPICH RSCP -8dB

best CPICH RSCP -8dB

2nd best CPICH RSCP <

-71 dBm

-71 dBm

-72 dBm

-79 dBm

th


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Important Criteria for Cluster Integration There are four important criteria for best practice while performing a cluster integration drive test: Criteria 1: Optimizing UL Coverage Criteria 2: Optimizing DL Coverage Criteria 3: Avoiding Pilot Pollution Criteria 4: Avoiding Cell Overlap The first two criteria are the pilot coverage criteria including slow fading losses. They are drawn from the link budget calculation. Bear in mind that these pilot coverage criteria give the uplink coverage indication for the limiting service for the morphology only when CPICH power settings are set to its default values: 30 dBm at antenna entrance The third criteria is taken from the pilot pollution criteria and defined for 3G radio design. The fourth criteria is taken from the cell overlap criteria. The measurement conditions for pilot pollution and cell overlap cannot be taken immediately from the measurement but can be calculated using Actix Software. The plots and queries that need to be visualized, and examples of the reports that can be drawn from a drivetest, can be generated automatically (see the following pages). In this stage, apart from fulfilling the above mentioned criterion as much as possible, we should try to minimize interference induced or caused in neighbour cells. For this purpose we will visualize the CPICH RSCP per SC. From this plot we will detect any unnecessary coverage outside the area where the SC is dominant. Action should be undertaken to avoid overshooting and unnecessary leaking into neighbour cells.


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Criteria 1: Optimizing UL Coverage

The map above is a combination of different drive tests in the same cluster. The attribute CPICH_Scan_RSCP_Sortedby_EcIo_0 is dragged and dropped different times on the map view. Best practice: The better solution is to create a super stream of all files from one cluster and perform the analysis on the super stream. In this map, we only have problems of UL coverage outside the cluster and in the centre of the 3 sites. The next necessary step is to find out where we have the dominant servers. We can do this by displaying the CPICH_Scan_SC_Sortedby_EcIo_0 attribute on the map to find out the dominance areas.


53


54

Criteria 2: Optimizing DL coverage

Not much problem for the example above, only some degraded downlink quality at the edge of the cluster. This is due to edge of coverage.


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Criteria 3: Avoiding pilot pollution In order to detect pilot pollution, the following criterion needs to be checked: Number of [Best CPICH Ec/Io - CPICH Ec/Io

2 x SH O_ w in dow

]

4

All measurement points fulfilling the criterion above suffer from pilot pollution and optimization changes need to be undertaken. The possible solution for pilot pollution can be: Up tilt the antenna providing the best server in the area in order to improve the CPICH RSCP Down tilt the antennas from interfering cells and as such reduce the RSSI. Change azimuth from antennas in order to create a dominant server in the polluted area. In the following graph you can detect an area of pilot pollution. The next step in this case would be to detect which of the surrounding sites is covering the area and to try to limit the amount of servers through up- and down tilting. That comes down to creating 1 or 2 dominant servers.


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Criteria 4: Avoiding cell overlap In order to detect cell overlap, the following criteria need to be checked if 3 rd best CPICH RSCP > - 71 dBm For measurement points where the criterion is fulfilled, we need to adopt more down tilt in order to reduce the CPICH RSCP. As such mutual interference will be reduced in the neighbour cells and we will have a more stable system.

In the example above, there is only some coverage overlap on area were the sites are built very close to each other. By applying the appropriate tilt and azimuth, you can avoid this problem.


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M issing neighbours Missing Neighbour Analysis is a fundamental aspect to WCDMA network optimisation. It should be performed as part of the rollout phase of a network to construct and/or optimise the adjacency lists of each cell; and throughout the life of the network as changes to traffic and tilt affect the coverage pattern and interference interaction between the cells. Missing Neighbour Analysis in Actix RVS solution has been designed to allow engineers to generate a list of suggested Missing Neighbours and allow engineers to visualise the suggested cells on a map. Full control of the suggestion criteria is included to allow for changes in clutter, terrain and rollout phase of the network. These suggestion criteria are described as follows:

WCD Neighbour List Settings: Tools > Preferences These criteria are applied to the scanned signal measurements to build a suggested list of cells. Only cells which satisfy all criteria are included in the final list of suggested Missing Neighbours.


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Preference Settings Description

Criteria Default

Value Description


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Missing Neighbours Example The following example explains how the Missing Neighbours are calculated:

Example Scanner Measurement drive. SC 103 on Site 1 is the strongest signal at point X

In this example, at point X , SC 103 is the Nth_Best SC (CPICH_Scan_SC_SortedBy_EcIo_0). The closest cell to point X is at Site 11. Its adjacency list includes 101, 102, 201 and 202. At point X , the scanned list is as follows:

S At point X , the strongest signal is SC 103 is at -5dBm. Applying the Reporting Range of 5dB creates a short-list of SC 202, 302, 203, 402 and 301 (greater than -10dBm). The signals from SC 101 and 303 are too weak to be considered. Note: The scanner reports SC numbers, so Actix RVS selects the closest cell to the drive route at that time, with a matching SC. 1


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SC 202 is already defined as a neighbour of SC 103, so this is eliminated too, leaving us with a suggested list of 203, 302, 402 and 301. Applying the intersite distance threshold, SC 402 is over 5Km away from SC 103, so it is removed from the suggested list, leaving us with SC 203, 302 and 301. The angle between the point X and the azimuth of the SC s is now analysed. To be considered, the azimuth must fall with +/- 90 degrees of the line-of-sight vector from the point X to that site. To allow for the spread of beamwidth, half the beamwidth is added/subtracted to the azimuth to give extra tolerance of angle.

Example of angle to site threshold for validation of SC 203, 302 and 302

When half the beamwidth is added/subtracted (depending on whether the azimuth is to the left or right of the vector connecting the scanner point and the cell) to the azimuth of the cell, the final criteria is applied to the cell. If the angle of the cell then falls within the angle setting in Tools Preferences the cell will be included in the suggested list. In the example above, SC 302 is included as a Missing Neighbour. The azimuth of SC 301 was originally outside our 90 threshold, but when subtracting half its beamwidth, it falls within our acceptable range so is therefore included as a Missing Neighbour. The azimuth of SC 203 + half its beamwidth still does not fall within our 90 threshold, so it is not included in the list.


61

Our final list of Missing Neighbours is then 301 and 302. Due to the fact that SC 302 has a stronger EcIo value than SC 301 at point X , the Missing Neighbours at point X are as follows: Missing_Neighbours_0 = 302 Missing_Neighbours_1 = 301 ..relative to CPICH_Scan_SC_SortedBy_EcIo_0 = 103 at point X . This is repeated for all points in the scanned drivetest route, creating an array of SC s at each point, sorted by their EcIo value, which satisfy the selection criteria and are not currently defined as a neighbour of the Nth_Best_0 cell at that time. If the Only use Nth Best cell option is disabled, not only the Nth_Best cell will be considered. Using the principle that if cell A and cell B are within 5dB, and cell A and cell C are within 5dB, the relationship between cell B and cell C should be analysed too. This obviously increases where processing is needed at each point, and is recommended for neighbour list optimisation of more mature networks. Once the final list of suggested Missing Neighbours has been compiled, the results can be viewed in two ways: through the Accelerated Network Rollout Analysis pack report (Neighbour List Recommendations), and also by visualising them on the map/chart/table.


62

Neighbour List Recommendations report Once this report has been run from the ANR analysis pack, the recommended additions/ removals / retentions are presented in a tabular format as follows:

In this example, SC 110 (Site123-a) was the Nth_Best measurement for 5000 samples during the scanner measurement. It s current adjacency list includes SC 112 and 113. While SC 111 was the Nth_Best cells, there were 1250 samples of SC 200, 500 samples for SC 112 and only 5 samples for SC 113 (sorted by % samples). SC 200 is not already in the adjacency list for SC 110, all criteria have been met for this cell, so it is suggested as a Missing Neighbour. SC 112 was scanned enough times to recommend to be kept in the adjacency list. SC 113 (at the same site as SC 112, 3.5Km away from SC 110) was only scanned 5 times, so it has been recommended to be removed. NOTE: It is important to drive enough routes and collect enough data to ensure these cell suggestions are statistically valid.


63

Missing and Removal Neighbour attributes In the workspace explorer, a new grouping has been introduced. Neighbour Analysis containing 2 sorted lists, for Missing Neighbour suggestions and Removal suggestions.

Workspace Explorer showing new Neighbour Analysis group

The lists are sorted by signal strength and contain the SC values of the cells in the list at each point in the scanned drivetest. The strongest Missing Neighbour (Missing_Neighbour_0) should be analysed first, as it could potentially be the strongest pollution source at that time. Drag the parameter onto the map and open the Top 10 Scan Measurements stateform (optionally dock it to under the Workspace Explorer). The legend of the map gives you the list of SCs that were the strongest Missing Neighbour at any point in the drive. The most frequent SC should be targeted first, and by selecting any point in the map, the stateform will synchronise to show the top 10 scanned measurements giving the Nth_Best SC at the top of the list2. A decision needs to be made whether to add this suggested Missing Neighbour SC into the adjacency list of the Nth_Best SC.

2

In the case of repeated SC values, the closest cell with a matching SC to the Nth_Best_0 cell will be selected.


64

Screenshot of Nth_Best SC (CPICH_Scan_SC_SortedBy_EcIo_0) plotted on the map. Missing_Neighbours_0 is added to the map, and synchronised to the Top 10 Scan Measurements stateform. The Display Cell Data view shows t he a dj a ce ncy list of ce ll e x a m ple 0 1 8 4 c (SC 242).

Once all the strongest Missing Neighbours have been analysed, the next strongest signal should be analysed. Following this process with ensure that the most important Missing Neighbours are analysed first. The same SC could appear as a Missing Neighbour for multiple Nth_Best cells, so it may be easier to create a Crosstab query with two dimensions: Missing_Neighbours_0 and Nth_Best_0, to give all occurrences of the combinations. This list can then be filtered from the Statistics Explorer to filter the map view for single SC combinations individually.


65

Screenshot showing validation of intersite distance between Nth- Best SC 242 at site Example0184 and Missing Neighbour 202 at site Example0199. The map s distance tool has been used and the distance 1.7046Km is underlined.


66

Dropped Call Analysis due to Missing Neighbours Neighbour list analysis can also be used verify the reason behind a dropped call. This method uses the process of combining the scanner and UE together and checking the Active and Monitored Sets for the UE against the scanned measurements at the point of a dropped call.

Screenshot showing synchronised scanner and handset traces, indicating Missing Neighbour 202 (and differences between best scanned SC 242 and Active Set SC 338.

This requires the scanner and UE traces to be collected at the same time, and for the resulting collection files to be superstreamed together (and correcting any time offset between the collection devices). See the online Help for instructions on superstreaming using Time Offsets. Once the files have been combined, parameters such as the UTRA_UE_CarrierRSSI and the Uu_CallDropped event can be dragged onto the map. By opening the UE Missing Neighbours stateform for the superstream and synchronising it with dropped call, the top 10 scanned measurements can be visually compared to the Active and Monitored sets for the UE at the time.


67

Screenshot showing how dropped calls from the handset can be viewed with the Missing Neighbour attributes when the scanner and handset are synchronised. Here the Active Set and Monitored Set SC s are at very low RSCP values, and poor EcNo too. The scanner detected 3 other SCs, and a missing neighbour just before the drop.

This allows the engineer to understand whether the UE had dropped a call due to a missing neighbour not being defined in the cell s adjacency list, or whether it was a handset problem, resulting in a neighbour that had already been defined not being added to the Monitored Set, and therefore never being able to be added to the Active Set.


68

Missing Neighbours Attributes Uu_MissingNeighbour (Missing Neighbours) Actix Software s event detection allows you to visualize missing neighbour on a map with drive test data. The missing neighbour event occurs when a particular SC is not in the neighbour list and forces the call to drop. The following procedure is followed to trigger the event. When the drop call occurs, a specific function looks for the next origination and gets the value of the new SC in the active set. If the new SC is different from the SC s in the active set before the call dropped, the function looks for the last neighbour list before the call dropped. If that same neighbour list does not contain the new SC, it is a possible missing neighbour. So, in other words: o If (SC in active set after drop call) <> (SC s in active set before drop call and Neighbour list before drop call) then missing neighbour o In this case, the engineer needs to understand the coverage issues. If the new SC is not meant to cover the specific area, optimization is probably the best solution and the engineer should not add the specific neighbour.

Example of missing neighbour before a dropped call


69

Uu_UE_NbrList, Uu_UE_NbrListCount (UMTS Neighbour List) These attributes are generated from Measurement Control signaling within file. The Measurement Control messages are sent from the network to the UE during a RRC connection. They can contain the list of the available neighbours (Scrambling codes) a UE should consider in it s measurement procedures. The first of these Measurement Control messages usually is the setup Mode, meanwhile the concessive ones are modify mode (i.e. changing the list). After the RRC connection procedure the algorithm, considers the first Measurement Control message to be the Setup and builds up an internal array of Scrambling Code with their corresponding index numbers (from attributes Uu_RRC_NewIntraFreqCell_intraFreqCellID and Uu_RRC_PrimaryCPICH_Info_primaryScramblingCode). This information is then used to populate attributes Uu_UE_NbrList and Uu_UE_NbrListCount (i.e. the number of SCs in the array). Concessive Measurement Control messages then modify this list, this continues until a new RRC Setup procedure is detected at which point the array is reset. Note: If there are any missing Measurement Control messages, this neighbour list will become out of sync with the true neighbour list being measured by the UE.


70

Scanner Based Network Rollout Analyses: Neighbou r List Analysis The Neighbour List Analysis provides an automated approach for generating optimal neighbour lists and overcoming major service degrading problems such as missing neighbours. The key components of the neighbor list module are: Generation of recommendations for optimal neighbor list settings based on UMTS/WCDMA scanner drive test data. Integration with Network Element Database to audit existing neighbor lists and suggest changes, and to correlate non-unique measured data attributes such as Scrambling Code with unique identifiers such as Sector ID. The Neighbor List Module implements the following algorithm: Ec/Io measurements below a noise floor are filtered out of the data set before analysis. User definable binning is used to reduce the number of measurement points in each bin to create one value per bin optionally, no binning at all can be applied and the analysis will run on the full data set. At each point along the drive test, a list of prospective neighbors is accumulated. If a neighbor signal is within a user-definable threshold of the best server in the active set, then it is considered as a potential neighbor. Using the geographic information in the log file and the SC, the network element database is searched to identify the Sector and Cell IDs of the SC. Once all the bins in the log file have been compiled into the symmetrical matrix, the results are compared against actual neighbor lists contained in the network element database and the following are calculated: o A list of sector IDs included in the matrix, but not the actual neighbor list. o A list of sector IDs included in the actual list, but not the matrix.


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C Neighbour 2

Figure 1 - Neighbor List Analysis Example

In the figure above, Cell A is the best server by CPICH Ec/Io. Cells B and C are within a user-specified threshold of Cell A's are Ec/Io, and so are counted as potential neighbors of A. Cell D is not within the required threshold and so is not counted as a prospective neighbor, nor is Cell E which did not have a measurable signal contribution at this point in the drive test. Here is a sample symmetric prospective neighbor array using sector IDs A, B, C and D:

A B C D

A

B

C

D

N/A 10 2 15

10 N/A 40 0

2 40 N/A 12

15 0 12 N/A

The limitations of this algorithm are: Results are only produced in areas that have been tested, so the test areas should be carefully considered before removing any Sectors from the neighbor lists. Drive test do not necessarily emulate the radio environment encountered by pedestrian and in-building users; however, walk tests and in-building test may be included in the analysis as desired.


72

Perform the following steps to access the Neighbour List Recommendations report: Step Action 1

Ensure that a suitable UMTS scanner file and corresponding Network Element Database are loaded in the workspace.

2

Configuration parameters for this analysis can be set by selecting Tools Preferences WCDMA Neighbour List. The configuration preferences include the reporting range, maximum list size, addition and removal thresholds and minimum number of samples to include a server in the analysis.

3

From the main menu, select Analysis Network Rollout.

4

Double-click on the Neighbour List Recommendations report icon in the lower pane of the Application Pack.

UMTS Accelerated

If there is no cell site database corresponding to the current dataset, or if the current cell site database does not contain neighbor list information, the report will work, though the results in the Cell , Site and Action columns will be invalid.

Figure 2 - Neighbor List Recommendations Report Output


73

Interference Factor (F Factor) The DL interference factor (also known as F factor) for a mobile station is the ratio of received power from external cells over the received power of the serving cell. This factor mainly depends on the relative position of the mobile in the cell, the relative load of the neighbouring cells, the morphology of the environment and the degree of optimization of the network. The DL interference factor has a great impact on the required transmit power per service for one particular user. As such we need to limit as much as possible this value of F in the cell and particularly at the cell edge. In the below is given a distribution of F on an optimized network in a suburban environment. SU F_DL

2 3 .1 2 6 .7

3 3 .0

40

H6 5 V 6 T0 H6 5 V 6 T2

2 .6 2 .4 2 .0

3 .4 3 .1 2 .6

4 .3 4 .0 3 .5

5 .7 5 .1 4 .5

7 .2 6 .7 6 .0

10

6 .6 6 .1 4 .6

H6 5 V 6 T4 9 .8 9 .6 8 .9

20

8 .2 7 .9 7 .3

1 6 .7 1 6 .5 1 6 .5

30

1 2 .2 1 1 .9 1 1 .0

F_DL cov e r ag e p e r ce n t ag e

50

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Area with too much interference

The graph above shows the F factor on a map and indicates areas where we have too much interference. In this example, F factor is smaller than 2 covers 95% of the area.


74

The F factor is also an indication of pilot pollution, where the higher the F factor is, the more the coverage quality will suffer from an increased load.


75

DL Interference factor versus path loss The graph below shows a typical representation of the F factor versus the cell edge, expressed as a ratio of path loss i.e. the path loss of mobile position over the max permissible path loss at cell edge. Note: F factor will be equal to 2 when the mobile station is at the cell edge. Relation between interference factor F and fraction of path loss (path loss/path loss at cell edge) 4 y = 0.0023e

4

6.7541x

3

F

3 2 2

F Expon. (F)

1 1 0 0.40

0.60

0.80

1.00

1.20

Fraction DL PL

F Factor vs. Path Loss


76

F Factor Report

8

0

7 -5

5

-10 EcIo

F factor

6

4 -15

3 2

-20

1 -25 -88.5 -91.5 -94.5 -97.5 -100.5 -103.5 -106.5 -109.5 -112.5 -115.5 -118.5 -121.5 -124.5 -127.5 -130.5 -133.5 -136.5 -139.5 -142.5 -145.5 -148.5 -151.5 -154.5 -157.5 -160.5 -163.5 -166.5 -169.5 -172.5 -175.5 -178.5

0

Path Loss (dB) in 3dB steps

F Factor Report

This graph is produced by the F Factor report. It shows the distribution of EcIo and F factor for different values of the pathloss. It gives us a signature for a certain area or cell and will give us visual information if a certain area is well-optimised or not. You can open this report at: Workbook Open Workbook/Report

F_Factor Report.xls


77

Example: Coverage Analysis Objective The objective of this example is to find out bad pilot coverage areas within the network. We will then determine whether the problem is localized, and the effect that the problem is having on the network quality.

Attributes Uu_ActiveSet_RSCP_0 Uu_CallDropped Uu_IncomingCallSetupFail Uu_OutgoingCallSetupFail Uu_Trch_DownlinkBlerAgg CPICH_AllSets_UE_RSCP_For_SC

Stateforms UMTS UE Active Set + Monitor Set

Queries Poor Mobile Receive Power, or Low Mobile Receive Power (Condition: Uu_ActiveSet_RSCP_0 < -95dBm)

Screen Layout UMTS Coverage Analysis Flirst click on the stream name, then click on Layouts UMTS UMTS Coverage Analysis


78

Coverage Analysis Procedure Step

Action

1

Superstream logfiles.

2

Display Uu_ActiveSet_RSCP_0, Uu_CallDropped, Uu_IncomingCallSetupFail and Uu_OutgoingCallSetupFail on the map.

3

Display Uu_ActiveSet_RSCP_0, Uu_TrCh_DownlinkBlerAgg, and ServingCellDistance on a table.

4

Apply Poor Mobile Receive Power or Low Mobile Receive Power.

5

Find and investigate further area with poor coverage and drop calls.

6

Use distance tool to find sites that provides adequate coverage to this region.

7

Un-apply filter and close all open windows.

8

Display Pilot Measurement CPICH_AllSets_UE_RSCP_For_SC for the three sectors that would be expected to provide coverage in problem area.

9

Investigate further to conclude your findings.


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Example: CPICH Pollution Analysis The CPICH or Pilot Pollution Analysis uses an Simulated Active Set to estimate which pilots would have been actively demodulated by the UE, and then detects other pilots above a user-definable threshold that cause excessive interference. Please see the Simulated Active Set section for more details on how the Active Set is estimated based on WCDMA scanner measurements. The pilot pollution algorithm has these components: Ec/Io measurements below a noise floor are filtered out of the data set prior to analysis. User definable binning is used to reduce the number of measurement points in each bin to create one value per bin optionally, no binning at all can be applied and the analysis will run on the full data set. At each point along the drive test, CPICH Ec/Io data for each Scrambling Code is used to assign SCs to an Active Set or a Pollution Set (please see the Simulated Active Set section for more details). The Pollution Set consists of all SCs that are not in the Active Set, and have a CPICH Ec/Io within a user specified pollution threshold of the strongest CPICH Ec/Io in the Active Set. Using the geographic information in the log file and the SC, the network element database is searched to identify the Sector and Cell IDs of the SC. A pollution array is created in memory which records the number of times each sector ID is seen as a source of pilot pollution. All bins in the log file are then processed into the pollution matrix.


80

A Active Set

Figure 3 - CPICH Pollution Analysis Example

In the example above, Cells A, B and C are part of the Active Set, as determined by the Simulated Active Set module. Cell D has a CPICH Ec/Io within a user-specified pollution threshold of the Active Set s best server Ec/Io, and so is counted as a contributer to pilot pollution at this point in the drive test. Cell E has a CPICH Ec/Io that is not within this threshold and so is not a pollution source. Shown below is a sample pollution array indicating the number of points at which each sector caused pilot pollution for sector IDs A, B, C and D: Sector ID A

Pollution Count 0

B

150

C

45

D

12

Results are presented in the Pilot Pollution Analysis application report. In addition, Pilot Pollution may be geographically analyzed for each SC by accessing the Pollution_for_SC attribute in the workspace view.


81

Perform the following steps to access the Pilot Pollution Analysis report: Step Action 1


2


3

Double-click on the Pilot Pollution Analysis report icon in the lower pane of the Application Pack.

4

Double-click on the Pilot Pollution Analysis report icon in the lower pane of the Application Pack.

5

Enter the Pilot Pollution Margin (dB). This margin is used to determine which pilots in the monitored set are within close proximity to the strongest pilot in the active set.

UMTS Accelerated

As shown below, the Pilot Pollution Analysis Report indicates the worst interferers sorted by Scrambling Code:

Figure 4 - Pilot Pollution Analysis Report Output


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Second Drive Test: Dedicated Mode with SC Scanning

Drive Test 2: Dedicated Mode with SC Scanning


83

Dedicated Drive Test The dedicated drive test is performed to check radio conditions in dedicated mode. For this test, two UE traces in dedicated mode will be logged, in parallel with a scan drive test. A call trace will be launched on both UEs in order to log uplink information and UE related Iub and Iu messaging. The two UEs will call each other, the mobile originating call will have automated call setup and release sequences. The measurement setup is identical as the first drive test (with external antennas). The configuration is as follows: UE 1 o o o UE 2 o

video call (voice call if not possible) mobile originating 90 seconds call 10 seconds guard before new call is set up Video call mobile terminating

The following results will be checked against the requirements: Criteria DU Area Urban Sub-Urban UE 1 Tx pwr < UE 1 BLER < UE 2 Tx pwr < UE 2 BLER <

-2 dBm

-2 dBm

-2 dBm

1%

1%

1%

-2 dBm

-2 dBm

-2 dBm

1%

1%

1%

Apart from the coverage criteria, the dropped calls will be analyzed. The cluster integration is successful when no dropped calls are due to radio quality. Note that this is only applicable when the cluster is fully built. If radio drops are a consequence of a missing site (and the site is in the final design), they cannot be a blocking point for cluster integration at this point. Analyzing dropped calls to determine the cause can be done using Analyzer, which enables to see decoded RRC messages. A dropped call usually occurs during an abnormal behaviour in one of the following procedures: call setup CS and PS call clearing soft handoff If a call drops the messaging before the drop should be checked and compared with the normal messaging sequences.


84

In order to find the cause for a dropped call, we should approach the problem in a structured way and always look at the different possible causes in the same way. Actix Software has many ways to endorse this procedure, and one of them is displaying the results on the Statistic Explorer. The sequence to check were the cause for dropping is can be as follows: Import and run Drop Analysis Crosstab Query to obtain the information mention below:

a) Active Set CPICH Ec/Io (and CPICH RSCP) I nformation to look for Ec/Io below the threshold?

If Yes, check if Out of coverage DL?

High F factor?

Due to pilot pollution?

Low F factor and good RSCP?

Due to load

Ec/Io below the monitored set?

Failed handover?

Ec/Io below the scanned best SC?

Missing neighbour?

RSCP below 115 dBm?

Out of coverage UL

b) DL BLER Information to look for

If Yes

When DL BLER > 10%

Start of DL channel limitation

When DL BLER > 50%

DL channel lost

c) RRC Messages Information to look for

If Yes

Synchronize RRC message flow with drop Check last seconds messaging Normal termination with cause?

Check cause

Measurement reports

Due to Failed HO?

During active set update

Radio synchronization


85

Types of D rops (Radio and Non- Radio Related) : The typical types of radio drops are due to the following problems: Missing Neighbours Low RSCP or Low Ec/Io UE Tx Power The other types of non- radio related drops are due to the following problems: Mobile Issue Core Network Issue

Types of Radio Drops Examples: 1. Missing neighbour See Dropped Call Analysis due to Missing Neighbours in pg 67.

2. Low RSCP or Low Ec/Io Low RSCP is mainly when there is no server in the area, while low Ec/Io is when there is no dominant server with a good quality. They may be combined as in this example:

Call Dropped due to Low CPICH and Low RSCP


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The example shows a drop due to low CPICH RSCP. Further analysis will show that on this point, the situation could be avoided by optimising the cell with SC100. In this case there is no other way to optimize this area than adding a new site, as no other antenna change will improve the situation. Else low RSCP can be improve by up tilt, and low Ec/Io by giving only one sector dominant in the area where the drop occurs.

3. UE TX power

No example from pre-launch. This will hardly ever happen since the measurements are taken out door, while our design is done for indoor coverage. The only possible occurrence of this problem is where we drive outside 3G coverage areas. This will only happen during the exit criterion drive test.


87

Types of Non- Radio Related Drops Examples:

Non-radio related drop example

The reason of call drop in the example above is not very clear, but the BLER goes up to 100% and the serving cells are not the obvious ones. A downlink power limitation is probably the reason for this. 1. Mobile Issue CM service abort, pegged as a drop, but coming from a cancellation on mobile side 2. Core Network Issue Disconnect received as there are a temporary unavailability from the CS side.


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Example: Dropped Call Analysis Objective The objective of this example is to analyze each dropped call (10 seconds before and 5 seconds after) and report a possible diagnosis.

Attributes Uu_ActiveSet_SC_0 Uu_IncomingCallOK Uu_OutgoingCallOK Uu_CallDropped CPICH_AllSets_UE_RSCP_For_SC

Stateform UMTS UE Active + Monitor Set

Queries UMTS Call Statistics query shows which File/Sector/Cell/Call ID that contains the drop call. Which one should we look at? Dropped Call Analysis query shows event and what causes the drop


89

Dropped Call Analysis Procedure Step 1

Action Superstream logfiles. Display Drop Analysis crosstab query or drop call related query on Statistic Explorer to obtain the following information:

2

Drop Call RSSI BLER

3

Exam and further investigate the result (i.e: Check out which File contains the drop call).

4

Close Statistic Explorer and open the problematic file. Superstream them if there are more than 1 file.

5

Display Uu_ActiveSet_SC_0, Uu_IncomingCallOK, Uu_OutgoingCallOK, and Uu_CallDropped on the map. Display the relevant attributes on tables and chart if necessary.

6

Zoom in on the Call Dropped event.

7

Display UMTS UE Active + Monitored Set stateform. Note: Make sure the stateform is synchronized with the map.

8

Display the Direction arrow

9

If necessary, select a data point shortly before the start of the call, and use the Replay Tool to step toward the drop.

to verify the drive test route

direction.

10

Observe the information displayed on the stateform as the drop approaches.

11

Display Pilot Measurement CPICH_AllSets_UE_RSCP_For_SC for the three sectors that would be expected to provide coverage in problem area.

12



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Example: Call Setup Failure Analysis Objective The objective of this example is to investigate the call setup failure based on the layer 3 messaging for call setup procedures.

Attributes Uu_IncomingCallSetupFail Uu_OutgoingCallSetupFail Uu_ActiveSet_SC_0 Uu_ActiveSet_EcNo_0 UE_TxPow

Stateform N/A

Queries UMTS Call Setup Statistic, or UMTS Call Setup Failure Analysis

Application Packs UMTS Call Setup Analysis


91

Call Setup Failure Analysis Procedure Step

Action

1

Superstream logfiles.

2

Display Call Setup Statistic by File Name crosstab query or Call Setup Failure on Statistic Explorer to obtain the call setup information.

3

Exam and further investigate the result (i.e: Check out which File contains the call setup failures).

4

Close Statistic Explorer and open the problematic file. Superstream them if there are more than 1 file.

5

Run UMTS Call Setup Analysis Application Pack to learn the additional information about the call setup failure events by sorting the data by Failed MOC Setups.

6

In the same Application Pack, run the Call Setup Status report to find out the reasons why the call failed.

7

Switch back to the UMTS Call Setup Analysis Application Pack window.

8

In the same Application Pack, run the Call Sequence Outcome report to find out the procedures carried out during the call setup phase for each call on the drive route.

9

Display Uu_InComingCallSetupFail, Uu_OutgoingCallSetupFail, Uu_ActiveSet_RSCP_0, and Uu_ActiveSet_EcNo_0 on the chart.

10

Display Protocol Stack Browser (UMTS Radio Interface view) and synchronize with the chart

11

Observe if any unusual event such as if a mobile sends a CM Service Abort immediately after the CM Service Request; or any repeated Connection Request.

12

Display UE_TxPow on the same chart and synchronize with the call setup failure.

13



92

Exit Criterion Drive Test In order to have a clear view on the performance of the cluster a third session of drive tests is organized. The aim of the exit criterion is to give us a quality indication on: the border of the cluster and interaction with neighbour clusters 3G 2G mobility status of cluster (KPI s) Accessibility Drive tests executed for the exit criterion need to fulfil different requirements than those performed for the first 2 drive tests in the FN8c procedure: Routes don t need to be extreme dense, but should be nicely spread over the cluster. One route inside 3G coverage and a second one on the boarders of 3G-2G coverage. One route need to be defined on cluster borders in order to check HO planning in between clusters Drive tests are taken in car (UEs and scanner)


93

Drive Tests For best practise, it is recommended to perform two different drive tests using the same pre-defined route: Drive test 1: Within 3G coverage, focus on CR (setup, maintain and clear) Within the 3G coverage area, with existing scenario (in-car, route density etc) suitable o o

UE1 - DL 4Mb file UE2 - Accessibility CS-PS-CS (if not possible, separate CS and PS for different UEs) CS calls; 10 sec call and release with 5 sec guard PS calls; webpage attach and release with

Metrics o UE1 - DL Throughput (average), for successful calls o DL CR (call success rate, = Call setup, maintained and cleared) o UE2 - CR (call success rate, = Call setup, maintained and cleared) Targets o o

CR UE1 > 96% CR UE2 > 98%

Drive test 2 o UE 1: CS voice short call: 10 sec call and release with 5 sec guard o UE 2: PS file download: 10 sec call and release with 5 sec guard o The following statistics are taken from the drive tests: CS call setup success rate PS call setup success rate


94

Cluster Integration Report In Actix Software, you can open the pre-defined report UMTS Cluster Acceptance App Pack (Application Pack) from Analysis UMTS Cluster Acceptance App Pack to obtain the following information: 1. Coverage plots from the planning tool 2. General description of the cluster with description of missing sites etc 3. The tools used and the references of the drive tests 4. Plots before (1st drive) and after (2nd drive) of a. Drive Test Route b. CPICH best EcIo c. RSCP best d. Pilot pollution e. Cell overlap f. Individual site problems like overshooting, missing neighbours, etc 5. Statistics on the 4 criteria before and after 6. All implemented network changes 7. Analysis of remaining dropped calls


95

Exercise 3 : Cluster Integration Exam your own data Load logfile and check 4 criteria using Actix Software o Create query if necessary or run an application package/report if necessary. o Are there other ways to detect pilot pollution? o Study the dropped calls Load logfile with Troubleshooter and evaluate different approach. (if you have a Troubleshooter license)


96

Site Integration in integrated cluster When a site needs to be integrated in a cluster an adapted process needs to be followed. Since the site was not part of the detailed planning of the cluster, optimization changes will be needed on multiple cells within the cluster (or neighbour cluster). Before retuning the cluster, individual site integration needs to be performed. Before doing so ensure that: Planned SC is OK and as such no SC reuse in and around the cluster Planned frequency is NOT the frequency of the macro layer which is on air. Radio configuration and radio parameters are pre-optimized for interworking with the cluster. The site integration will be performed as described earlier, with the following additions: A complete cell drive test is performed; meaning all streets in the cell from close range until out of coverage . As such the coverage footprint will be detected and this will be used for cluster re-tuning. Post-processing of data is mandatory since it will be used for tuning the Node B in question and all cells bordering the optimized coverage footprint of the cells. When preparing the optimization changes of the new Node B and the surrounding cells, try to achieve the following: Equal cell ranges, meaning the equal power boundary is in the middle of the two Node B s. To do so the integration drive test needs to projected on top of the reference drive test of the cluster Prepare neighbour relations and prepare deletion of existing neighbour relations All optimization changes need to be performed at the same time. At this moment the frequency of the site needs to be changed to the frequency of the macro-layer. As soon as possible a complete drive test needs to be performed of check if the site is successfully inter-working with neighbour sites and eventually further optimize the cluster.


97

Chapter 6 Cell Reselection What is cell reselection? Cell reselection is the procedure where the UE reselects the cell from which he reads the BCCH. This happens in idle mode, but also in cell FACH and cell/URA PCH mode. In idle mode, the cell reselection can be detected through the decoding of a new BCCH. In cell PCH and cell FACH state, the reselection can be noticed by an RRC cell update message. The transitions from those states to idle mode and back can be detected by the following RRC messages: Physical channel reconfiguration Transport channel reconfiguration RRC connection release


98

Reselection Criteria Cell is suitable if this condition is fulfilled: S- Criterion for FDD cells: Srxlev > 0 AND Squal > 0 Where:

S qual = Qqualmeas - Qqualmin S rxlev = Qrxlevmeas - Qrxlevmin - Pcompensation Parameter Squal

Description Cell Selection quality value (dB) Applicable only for FDD cells.

Srxlev

Cell Selection RX level value (dB)

Qqualmeas

Measured cell quality value. The quality of the received signal expressed in CPICH Ec/N0 (dB) for FDD cells. CPICH Ec/N0 shall be averaged. Applicable only for FDD cells.

Qrxlevmeas

Measured cell RX level value. This is received signal, CPICH RSCP for FDD cells (dBm) and PCCPCH RSCP for TDD cells (dBm).

Qqualmin

Minimum required quality level in the cell (dB). Applicable only for FDD cells.

Qrxlevmin

Minimum required RX level in the cell (dBm)

Pcompensation

max(UE_TXPWR_MAX_RACH

UE_TXPWR_MAX_RA_CH

Maximum TX power level an UE may use when accessing the cell on RACH (read in system information) (dBm)

P_MAX

Maximum RF output power of the UE (dBm)

P_MAX, 0) (dB)


99

In order to perform cell reselection UE, measures and ranks the neighbour cells. For each type of neighbour cells (Intra freq, inter-freq, Inter-RAT) thresholds are definable. Measurements of neighbour cells will be triggered if these thresholds are reached. (Re-) Selected cell is a suitable cell (fulfils the S criterion) and is the best ranked cell (has the highest R). The UE shall however reselect the new cell, only if the following conditions are met: The new cell is better ranked than the serving cell during a time interval Treselection More than 1 second has elapsed since the UE has camped on the current serving cell In the below mentioned ranking criteria the following naming convention applies: s indicates the serving cell n indicates the candidate cell

Measurement Rules If Squal > Sintrasearch, UE need not perform intra-frequency measurements. If Squal <= Sintrasearch, perform intra-frequency measurements. If S intrasearch, is not sent for serving cell, perform intra-frequency measurements Reselect highest ranked if access not restricted: R- Criterion

R s = Qmeas,s + Qhysts R n = Qmeas,n Qoffsets,n


100

Intra Frequency Soft Handover Handover While moving from one cell to another, the best server conditions change and there is a need to redirect the mobile to a new serving base station. Unlike in GSM, WCDMA takes advantage of the time where the received signal strength of different pilot channels is within a certain window. During this time the mobile is connected to different serving base stations, this is called soft handover (softer if the serving cells are from the same Node B). In the case of soft handover the RNC performs selective combining on all the active links. This gives a typical gain of 4dB (2 links) or 5 dB (3 links), depending on the fading conditions. In the case of softer handover, the signals are rake processed in the Node B, and the gain is slightly higher. The following terminology is used to indicate the handover state of the mobile: Active Set The cells in the active set form a soft handover connection to the Ue Monitored Set The monitored set is the list of cells that the UE continuously measures, but which pilots are not strong enough to be added to the active set. This is the same set as the so-called neighbour list. Remaining Set Is the set of all the other scrambling codes in use, which are not in the active or the monitored set This name is not frequently used, only for planning purposes.

You can obtain the Intra-Freq handover information by displaying the UMTS Handover Analysis (Intra Freq) screen layout from Layouts UMTS UMTS Handover Analysis (Intra Freq)


101

H andover Events The following events and thresholds are in use in the WCDMA handover algorithm: Radio Link Addition Event 1A If Pilot Ec/Io > Best Pilot Ec/Io reporting range + hysteresis 1A for a period of t and the active set is not full, the cell is added to the active set. Radio Link Removal Event 1B If Pilot Ec/Io < Best Pilot Ec/Io reporting range hysteresis 1B for a period of t, then the cell is removed from the active set. Combined Radio Link Addition and Removal Event 1C If the active set is full and Best candidate Pilot Ec/Io > Worst Pilot Ec/Io + hysteresis 1C for a period of t, then the weakest cell in the active cell is replaced by the strongest candidate cell. These are the basic, standardised handover events and they are UE triggered event. As for other, more complicated handover algorithms will be vendor dependant and you can make use of the available measurement report data to obtain the information you need.


102

UE Measurement reports Depending on the handover type (MEHO or NEHO), different measurement reporting criteria can be used. These measurement reports give the necessary information to the RNC (NEHO) or UE (MEHO) to trigger a handover, but they also allow the RF engineer to understand the behaviour of the UE/network in certain conditions (load, location). Measurements done by the UE are collectable during drive tests, whereas Node B measurements have to be found in the Iub traces. In a UE report, the following Ies are included to identify the neighbours; PCPICH information, UTRA RF channel number (for IF measurement reports), BCCH freq (for GSM IS measurement report).

Event triggered Intra- Freq measurement report Event 1A: P-CPICH enters the reporting range Event 1B: P-CPICH leaves the reporting range Event 1C: non active P-CPICH becomes better than an active one Event 1D: Change of best cell (affects the reporting range, but not the active set) Event 1E: P-CPICH becomes better than an absolute threshold plus optional hyst. Event 1F: P-CPICH becomes worse than an absolute threshold minus optional hyst.

Periodic Intra- Frequency measurement report Event triggered measurement reports typically cause an active set update. If for one or another reason (hardware, software resources) this update cannot take place. The UE will switch to periodic reporting until, the HO took place, the conditions are no longer fulfilled or it has reached the maximum number of periodic measurement reports.

Inter- Frequency

Intersystem Measurement Report

They are always periodic and the way of using the measurements in handover algorithms is not part of the standard.


103

UE Internal measurements The UE internal measurements can be divided in two groups: measurements to indicate the status of the mobile TX power measurements to indicate the UE TX RX time difference The first group of measurements can be used by the RNC to trigger interRNC or system handover. The second group is used to adjust the downlink DPCH air interface timing, when the difference ion time between the UE uplink DPCCH/DPDCH frame transmission and the first significant path of the downlink DPCH frame from a measured active set cell becomes too large. Event 6A: UE TX power becomes larger than an absolute threshold Event 6B: UE TX power becomes less than an absolute threshold Event 6C: UE TX power reaches its minimum value (-50 dBm) Event 6D: UE TX power reaches its maximum value (21 dBm) Event 6E: UE RSSI reaches the UE s dynamic receiver range Event 6F: UE Rx Tx time difference for a radio link included in the active set becomes larger than an absolute threshold Event 6G: UE Rx Tx time difference for a radio link included in the active set becomes less than an absolute threshold


104

Handover Attributes and Related Events Uu_HandoffOK ( Handoff OK) ActiveSetUpdate message (Uu_RRC_MsgType == ActiveSetUpdate) ActiveSetUpdateComplete message (Uu_RRC_MsgType == ActiveSetUpdateComplete) Note: This attribute is only incremented if the RRC event Diagram is in the RRC Connected State.

Uu_HandoffFail (Handoff Failure) ActiveSetUpdate message (Uu_RRC_MsgType == ActiveSetUpdate) ActiveSetUpdateFailure message (Uu_RRC_MsgType == ActiveSetUpdateFailure) Note: This attribute is only incremented if the RRC event Diagram is in the RRC Connected State.

Uu_Handover_toGSM (Handover to GSM event OK) HandoverfromUTRANcommand Uu_RRC_MsgType == HandoverfromUTRANcommand-GSM And then GSM_Um_Msg_Type == RR Handover Complete OR GSM_Um_Msg_Type == RR Measurement Report for 10 concessive message CellChangeOrderfromUTRAN Uu_RRC_MsgType == CellChangeOrderfromUTRAN And then GSM_Um_Msg_Type == RR Channel Request OR GSM_Um_Msg_Type == RR Immediate Assignment OR GSM_Um_Msg_Type == RR Immediate Assignment Extended Note: One of the above must be received before the expiry of the timer Uu_t309_wait_timer


105

Uu_Handover_toGSM_Failure (Handover to GSM event Failure) HandoverfromUTRANcommand Uu_RRC_MsgType == HandoverfromUTRANcommand-GSM And then Uu_RRC_MsgType == HandoverFromUTRANFailure OR Any GSM or UMTS BCCH messages. OR GSM_Um_Msg_Type == RR Channel Request OR Uu_RRC_MsgType == RRC Connection Request CellChangeOrderfromUTRAN Uu_RRC_MsgType == CellChangeOrderfromUTRAN And then Uu_RRC_MsgType == CellChangeOrderFromUTRANFailure OR Any UMTS BCCH messages. OR Timer Expiry, which is configured by threshold Uu_T309_Wait_Timer OR Uu_RRC_MsgType == RRC Connection Request Uu_Handover_toUTRAN (Handover to UMTS event) Uu_RRC_MsgType == HandovertoUTRANcomplete Note: If a call is completed in GSM mode (after the handover from UTRAN to GSM), the call event will appear in the GSM section of the Workspace Explorer window.

Uu_IRAT_Reselection3G2G, Uu_IRAT_Reselection2G3G (IRAT Reselection) If a device is determined to be idle, and system information from the other technology is seen then there will be an event to indicate there has been a technology change. Uu_CellReselection (Cell Reselection) If a device is determined to be in Cell Fach and there is a server cell change, then there will be a event to indicate there has been a Cell reselection.


106

Uu_IFHO_OK (Inter-Freq Handover Event OK) This attributes indicates that a UE has performed an Inter-Freq handover successfully. Uu_IFHO_Failure (Inter-Freq Handover Event Failure) This attributes indicates that a UE has performed an Inter-Freq handover failure. Uu_UE_HandoffState (UE Handoff State) The handoff state algorithm has the following components: The Active Set information from the Handset Using the geographic information in the log file and the SC, the network element database is searched to identify the Sector and Cell IDs of the SC Handoff state is calculated by determining the configuration of the sectors in the Active Set


107

Handoff Analysis The Handoff Analysis module uses the Simulated Active Set to determine the handoff state at each point along a drive test. Statistics on handoff state may then be calculated and presented in a report format. Excessive handoff state reduces capacity and increases infrastructure costs for a given traffic level. Please see the Simulated Active Set section for more details on how the Active Set is estimated based on WCDMA scanner measurements. The handoff state algorithm has the following components: The Active Set of pilots is determined using the Simulated Active Set module. Using the geographic information in the log file and the SC, the network element database is searched to identify the Sector and Cell IDs of the SC. Handoff state is calculated by determining the configuration of the sectors in the Active Set. All bins in the log file are then processed into the handoff state matrix. Reports showing the percentage of handoff state for each sector and for the total drive test may then be calculated.


108

The Handoff State Analysis examines Sector IDs involved in call at a given drive test point and determines which of the above states applies, based on UMTS scanner data:

Figure 5 - Handoff State Descriptions

Perform the following steps to access the Handoff Analysis report: Step Action 1


2


3

Double-click on the Handoff Analysis report icon in the lower pane of the Application Pack.

UMTS Accelerated


109

The populated Handoff Analysis report will look like this:

Figure 6 - Handoff Analysis Report Output


110

Exercise 4 : Handover Exam Your Own Data Load logfile and select handover scenario Display on graph the quality indicators per cell Display handover triggers How can they be influenced (which parameters) Study missing neighbours Do we automatically add missing neighbours to the neighbour list?


111

Chapter 7 Report Creating Reports You may want to create high-level management reports based on your collected data. You can print from map and chart windows, but the Workbook function (using Microsoft Excel ) allows you to collate these views and perform other data analysis functions to produce an integrated, polished report. Actix makes the creation of user-definable report templates effortless, by allowing users to have a direct access to MS Excel. The easiest way to get data into reports is to use the right-mouse selection Display on Workbook, which automatically displays three types of datasets in Excel: series data, statistical data, and histogram data. Note: Series data always takes the longest to re-generate as a template.


112

Exercise 5: Single File Report Template Objective The objective of this exercise is to create a report template that will return KPIs from one file. Create a report template from existing parameters and queries which can be run on any file. This will return the total number of dropped calls, a histogram of the handoff state, the average call setup time, mean (linear) RSCP for the strongest SC in the Active Set and total call duration for all calls in the whole file.

Procedure Step

Action

1

Choose and load a log file.

2

Based on the requirement, this report can be separated into existing KPIs and new KPIs (new queries). Existing KPIs: Average call setup time (Uu_TimeBetweenRRC_REQandCallStart) Total Dropped Call (Uu_CallDropped) New KPIs: HandOff State Histogram Mean(linear) RSCP from the strongest Active Set SC Total Call duration for the whole file The Handoff State is an attribute (Dedicated Radio Link Uu_UE_HandOffState) that you can drag and drop to a workbook to obtain an automatic histogram view of data. Somehow, we are trying to create a generic report template to be run on other files. To use the automatic view, the legends will be controlled through the format group of the parameter and may filter out ranges not found in the file. For this reason, we need to force the number of ranges used in the histogram through a query.

3

Display the call setup time parameter Uu_TimeBetweenRRC_REQandCallStart (from the UMTS Statistics Data data group) on a workbook.


113

Step 4

Action Keep the workbook open. Switch back to Actix Software and display the Uu_CallDropped (from UMTS Event Data Call data group) on the existing workbook (active workbook).

Notice how all three views from these two attributes have been added to the workbook (Series, Histogram and S.tatistic Formatted Data tabs). 5

Save your workbook

6

To create new query, goto Analysis Manager (ctrl- A)

7

Create a histogram query using the Uu_UE_HandoffState parameter, and creating discrete values from 0 (inclusive) to 6 (inclusive).

8

Create a crosstab query with FileName from the Attribute Picker(

) as the dimension, and add 2 new statistics for:

Mean (linear) of Uu_ActiveSet_RSCP[0] formatted as WCDMA RSCP, and Sum of Uu_CallDuration formatted as Time. 9

Save your query into the workspace and check the results are accurate.

10

Open the report template through the Workbook Open Workbook/Report menu option, and choose to run it on your log file.

11

Right-click on Queries folder, find your new query and display it on the existing workbook. It will be added to a new sheet called Crosstab Formatted Data.

12

These tabs will contain the results from whatever file you run the report template on. Open Sheet 1 and create your KPI statistics here as follows (see next page):


114

Holding Time or Mean Time Between Failures = call duration / drops (roughly)

From Statistics results

From Crosstab results

From Histogram results

Step

Action

13

Now go back into the all other sheets and delete the raw data from row 2 downwards. This cleans the report template so that it can be run on any other file, of varying size.

14

Save your report template.

15

Open another log file and run the report template on this file as you did in step 10. Compare the results.


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Where to Get More Help Help File Analyzer includes comprehensive online help, which can be accessed by clicking on Help menu on the main menu. The primary help documentation can be found under Help Con t e n t s. You can look up information about a particular topic either by choosing an item from the index or by entering keywords and performing a search.

Key Word

Search Result

Actix Online Help Showing Search Results For cellrefs

Specific information, like the definition of engineering parameters, can be accessed by clicking on Help Show Context Help. You can look up an item in the alphabetized list, or you can open the Context Help window, then click on an item in the Workspace.


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Attribute Definition

Selected Attribute

Highlighted Item in the Workspace and the Corresponding Entry in Attribute Help

The contents of the Help window can be printed, stored under Favorites, and resized or minimized to enable side-by-side review as operations are performed in Analyzer.


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Technical Support Technical support is available by phone, email, and on the Actix Web site. Technical personnel are located in London UK, USA, and Singapore to provide assistance. In the EMEA technical support can be reached at: Phone : +44 (02) 8735 6300 Email : [email protected] or [email protected] Web (Extranet): www.myactix.com

MyActix (Extranet) If you would like to obtain the latest information of the software release, problem reporting, support issues, access to our self-study modules or Knowledge Base, please register yourself at http://www.myActix.com

Click on Release tab to download the latest release of Actix Software Click on News tab Self- Study Module News Items to download all the self-study recordings (in WebEx and Flash) Click on Analyzer Knowledge Base to access information from Knowledge Base.


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Appendix A Event Data

UMTS Event Definitions

Call Events

Call Event Name

Triggering Sequence (1)

Uu_OutgoingCallOK

Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following: *RRC_OriginatingConversationalCall *RRC_OriginatingStreamingCall *RRC_OriginatingInteractiveCall *RRC_OriginatingBackgroundCall *RRC_OriginatingSubscribedTrafficCall *RRC_Registration (1)

Uu_RRC_MsgType == RRC Connection Setup

Uu_RRC_MsgType == RRC Connection Setup Complete

(1)

GSM_Um_Msg_Type == MM CM Service Request GSM_Um_Msg_Type == MM Authentication Request

(*)

GSM_Um_Msg_Type == MM Authentication Response Uu_RRC_MsgType == Security Mode Command Uu_RRC_MsgType == Security Mode Complete GSM_Um_Msg_Type == CC Setup

(*)

(*)

(*)

(*)

GSM_Um_Msg_Type == CC Call Proceeding Uu_RRC_MsgType == Radio Bearer Setup

(*)

(*)

Uu_RRC_MsgType == Radio Bearer Setup Complete GSM_Um_Msg_Type == CC Connect

(*)

(*)

GSM_Um_Msg_Type == CC Alerting OR CC Connect Acknowledge

(1)

At least one of those messages (RRC Connection Request, Setup or Complete) needs to be present to initiate the call setup

(*)

The messages with the symbol star are usually present but not mandatory

Uu_IncomingCallOK

Uu_RRC_MsgType == PagingType1 with Uu_RRC_PagingRecord_cn_Identity_pagingCause equals any of the following: *TerminatingConversationalCall *TerminatingStreamingCall *TerminatingInteractiveCall *TerminatingBackgroundCall (2)

Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following:


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Call Event Name

Triggering Sequence *TerminatingConversationalCall *TerminatingStreamingCall *TerminatingInteractiveCall *TerminatingBackgroundCall Uu_RRC_MsgType == RRC Connection Setup

(2)

Uu_RRC_MsgType == RRC Connection Setup Complete

(2)

GSM_Um_Msg_Type == RR Paging response GSM_Um_Msg_Type == MM Authentication Request

(*)

GSM_Um_Msg_Type == MM Authentication Response Uu_RRC_MsgType == Security Mode Command Uu_RRC_MsgType == Security Mode Complete GSM_Um_Msg_Type == CC Setup

(*)

(*)

(*)

(*)

GSM_Um_Msg_Type == CC Call Proceeding Uu_RRC_MsgType == Radio Bearer Setup

(*)

(*)

Uu_RRC_MsgType == Radio Bearer Setup Complete GSM_Um_Msg_Type == CC Connect

(*)

(*)

GSM_Um_Msg_Type == CC Alerting OR CC Connect Acknowledge (2)

At least one of those messages (RRC Connection Request, Setup or Complete) needs to be present to initiate the call setup. Paging type 1 message is required for an incoming call.

(1)

At least one of those messages (RRC Connection Request, Setup or Complete) needs to be present to initiate the call setup

(*)

The messages with the symbol star are usually present but not mandatory

Uu_OutgoingCallSetupFail

Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following: *RRC_OriginatingConversationalCall *RRC_OriginatingStreamingCall *RRC_OriginatingInteractiveCall *RRC_OriginatingBackgroundCall *RRC_OriginatingSubscribedTrafficCall *RRC_Registration Then any of the following options: *Uu_RRC_MsgType == RRC Connection Reject or *Uu_RRC_MsgType == RRC Connection Setup *Uu_RRC_MsgType == RRC Connection Release or *Any BCCH messages during the call setup


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Call Event Name Uu_IncomingCallSetupFail

Triggering Sequence Uu_RRC_MsgType == PagingType1 with Uu_RRC_PagingRecord_cn_Identity_pagingCause equals any of the following: *TerminatingConversationalCall *TerminatingStreamingCall *TerminatingInteractiveCall *TerminatingBackgroundCall Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following: *TerminatingConversationalCall *TerminatingStreamingCall *TerminatingInteractiveCall *TerminatingBackgroundCall Then any of the following options: *Uu_RRC_MsgType == RRC Connection Reject or *Uu_RRC_MsgType == RRC Connection Setup *Uu_RRC_MsgType == RRC Connection Release or *Any BCCH messages during the call setup

Uu_CallCompleted

When in Call (Outgoing Call Ok or Incoming Call Ok), you get one of the following messages: *GSM_Um_Msg_Type == CC Disconnect or *GSM_Um_Msg_Type == CC Release Complete or *GSM_Um_Msg_Type == CC Release And any of the above messages with a normal cause for ending the call (CauseCodeCC is equal or less than 31)

Uu_CallDropped

When in Call (Outgoing Call Ok or Incoming Call Ok), you get any of the following options: Any BCCH Message or Uu_RRC_MsgType == RRC Connection Release AND Release Cause is not Normal or One of the following messages: *(GSM_Um_Msg_Type == CC Disconnect) OR *(GSM_Um_Msg_Type == CC Release Complete) OR *(GSM_Um_Msg_Type == CC Release) *AND any of the above messages with NOT a normal cause for ending the call (CauseCodeCC is greater than 31)

Uu_LocationUpdateOK

GSM_Um_Msg_Type == MM Location Updating Request GSM_Um_Msg_Type == MM Location Updating Accept

Uu_LocationUpdateFail

GSM_Um_Msg_Type == MM Location Updating Request


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Call Event Name

Triggering Sequence GSM_Um_Msg_Type == MM Location Updating Reject

Event Data

RRC Events

RRC Event Name Uu_OutgoingRRC_ConnectionOK

Triggering Sequence Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following: *RRC_OriginatingConversationalCall *RRC_OriginatingStreamingCall *RRC_OriginatingInteractiveCall *RRC_OriginatingBackgroundCall *RRC_OriginatingSubscribedTrafficCall *RRC_Registration Uu_RRC_MsgType == RRC Connection Setup Uu_RRC_MsgType == RRC Connection Setup Complete

Uu_IncomingRRC_ConnectionOK

Uu_RRC_MsgType == RRC Connection Request with Uu_RRC_RRCConnectionRequest_establishmentCause equals any of the following: *TerminatingConversationalCall *TerminatingStreamingCall *TerminatingInteractiveCall *TerminatingBackgroundCall Uu_RRC_MsgType == RRC Connection Setup Uu_RRC_MsgType == RRC Connection Setup Complete


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Event Data

RAB Events

RAB Event Name

Triggering Sequence

Uu_RadioBearerSetupOK

RAB Setup message Followed by RAB Setup Complete

Uu_RadioBearerSetupFail

RAB Setup message Followed by RAB Setup Failure

Uu_RadioBearerReleaseOK

RAB Release message Followed by RAB Release Complete

Uu_RadioBearerReleaseFail

RAB Release message Followed by RAB Release Failure

Event Data

Coverage Events

All Coverage Events which make use of thresholds may be customized by the user in the Tools Display Thresholds menu. Coverage Event Name

Triggering Condition(s)

Uu_PilotPollution

4 or more pilots detected above Uu_PilotPollutionThreshold

Uu_TooManyServers

4 or more pilots are detected within X dB of the server, threshold X is set by the user as Uu_TooManyServersThreshold

Uu_System_Interference

CPICH_EcNo_in_ActiveSet < Uu_EcNoInterferenceThreshold and CPICH_RSCP_in_ActiveSet > Uu_RSCP_InterferenceThreshold

Uu_Coverage_Limited

CPICH_EcNo_in_ActiveSet < Uu_Poor_EcNoThreshold and CPICH_RSCP_in_ActiveSet < Uu_Poor_RSCP_Threshold and UeTransmittedPower > Uu_CoverageLimitedUE_TxPowerThreshold

Uu_PoorDL_Coverage

CPICH_EcNo_in_ActiveSet < Uu_Poor_EcNo_Threshold and CPICH_RSCP_in_ActiveSet < Uu_Poor_RSCP_Threshold and UeTransmittedPower < Uu_LowUE_TxPower_Threhold

Uu_PoorUL_Coverage

CPICH_EcNo_in_ActiveSet > Uu_Poor_EcNoThreshold and CPICH_RSCP_in_ActiveSet > Uu_Poor_RSCP_Threshold and UeTransmittedPower > Uu_HighUE_TxPower_Threshold


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Coverage Event Name

Triggering Condition(s)

Uu_HandoverProblem

This event monitors the Ec/No of Monitored Set SCs with the Ec/No of Active Set SCs in an 8 second window prior to each dropped call. The Uu_HandoverProblem event is pegged if the Monitored Set SCs are stronger than the Active Set SCs more often than the Active Set SCs are stronger than the Monited Set SCs.

Uu_MissingNeighbor

SC in Active Set after drop is not in Active Set before drop and SC in Active Set after drop is not in Neighbor List before drop

Event Data

Handoff Events

Handoff Event Name Uu_HandoffOK

Triggering Sequence ActiveSetUpdate message (Uu_RRC_MsgType == ActiveSetUpdate) ActiveSetUpdateComplete message (Uu_RRC_MsgType == ActiveSetUpdateComplete)

Uu_HandoffFail

ActiveSetUpdate message (Uu_RRC_MsgType == ActiveSetUpdate) ActiveSetUpdateFailure message (Uu_RRC_MsgType == ActiveSetUpdateFailure)


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100498575 Actix Troubleshooting and Optimizing UMTS Network

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