Optimizing Wcdma Ran

Nokia Siemens Networks WCDMA RAN, Rel. RU20, Operating Documentation, Draft, Issue 02

Optimizing WCDMA RAN

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Table of ContentsThis document has 25 pages.

Summary of changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1 Optimizing and expanding WCDMA RAN overview. . . . . . . . . . . . . . . . . 7

2 Principles of optimizing GSM/WCDMA interworking . . . . . . . . . . . . . . . 12

3 Operation and Management Server. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

4 Optimization use cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154.1 WCDMA adjacency optimization based on measurements . . . . . . . . . . 154.2 Soft handover analysis and optimization . . . . . . . . . . . . . . . . . . . . . . . . 184.3 Interference analysis for performance and coverage optimization . . . . 204.4 WCDMA capacity optimization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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List of TablesTable 1 Network element software requirements . . . . . . . . . . . . . . . . . . . . . . . . 15Table 2 Use case information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Table 3 Network element software requirements . . . . . . . . . . . . . . . . . . . . . . . . 18Table 4 Use case information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Table 5 Network element software requirements . . . . . . . . . . . . . . . . . . . . . . . . 20Table 6 Use case information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Table 7 Use case information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

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Optimizing WCDMA RAN Summary of changes

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Summary of changes Changes between document issues are cumulative. Therefore, the latest document issue contains all changes made to previous issues.

Changes between issues 10-0 and 10-1The identification numbers of certain RAN KPIs have changed in this release. This infor-mation has been updated in the document as follows:

IFHO Success Ratio (RNC168 or M1014C1/M1014C0) has been changed to IFHO Success Ratio (RNC_168a or M1014C1/M1014C0) in the section WCDMA adja-cency optimization based on measurements.

There have been changes to two KPI names in section WCDMA adjacency optimi-zation based on measurements: SHO Success Ratio (M1013C2/ M1013C3) has been changed to SHO Success

Ratio (M1013C1/ M1013C0.) SHO Average Ec/No Difference (Information available, but not yet an official

counter in RAN) has been changed to SHO Average Ec/No Difference (M1013C2/ M1013C3).

There have been changes to two KPI names in section Soft handover analysis and optimization: Average EcNo difference between cell A and cell B in the dropped call cases

(Information available, but not yet an official counter in RAN) has been changed to Average EcNo difference between cell A and cell B (M1013C2/M1013C3).

Soft Handover Overhead [%] for One Cell or whole RNC (RAN_KPI_0019) has been changed to Soft Handover Overhead [%] for One Cell or whole RNC (RNC_79b).

The list of interference analysis and optimization KPIs has been updated in section Interference analysis for performance and coverage optimization.

The list of KPIs for checking performance problems in the RNC has been updated in section WCDMA capacity optimization.

The KPIs for checking the performance problems of Iub/Iur have been updated as follows in section WCDMA capacity optimization: AAL2 resources availability in the RNC [%] has been updated to AAL2 connec-

tion reservation success rate [%] (RNC_602a) AAL2 path average reserved bandwidth [%] has been updated to AAL2 path

average reserved bandwidth [%] (RNC_601a).

Changes between issues 9-1 and 10-0

NEMU is not supported and has been replaced with OMS. SectionOperation and Maintenance Unit has been renamed Operation and Management Server.

Counter availability information related to KPIs has been updated in sections WCDMA adjacency optimisation based on measurements and Interference analysis for performance and coverage optimisation inOptimisation use cases.

Changes between issues 9-0 and 9-1Editorial changes have been made.

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Summary of changes

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Optimizing WCDMA RAN Optimizing and expanding WCDMA RAN overview

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1 Optimizing and expanding WCDMA RAN overviewPurposeThe main objectives of WCDMA RAN optimization are to enable a better availability of network services (coverage criteria) and to provide a pre-defined level of service quality and performance (Quality of Service criteria). Since the WCDMA network is often built on top of an existing GSM network, it is also essential to ensure seamless mobility within and between the networks. In mature WCDMA networks, capacity optimization also becomes very important.

Optimization based on coverage criteria:

Coverage for different data rate services and maximum loading based on traffic fore-casts and margins set for load variation. The cell breathing effect allows the cell size to vary according to the load - the smaller the load, the greater the coverage and vice versa.

Pilot channel coverage Soft handover areas and probabilitiesThe coverage criteria are met by pre-planning as well as continuous measuring, moni-toring and fine-tuning of the roll-out and the running network.

Optimization based on performance and capacity criteria:

Total data throughput in a cell End-user data throughput (application throughput) Delays Call setup success rates for different services Call drop rates Handover performanceThe Quality of Service criteria are verified by checking the KPIs related to them. For more information on KPIs, see Section Overview of WCDMA RAN key performance indi-cators in WCDMA RAN Key Performance Indicators.

Optimization based on mobility criteria:

Defining the neighbouring cells for seamless handovers Handover criteria and performance Soft handover connections and gains Service-based and load-based handover optimizationIn multi-technology and multi-service networks, mobility-based optimization is challeng-ing. Due to the dynamic nature of the WCDMA (load coverage capacity), it is often necessary to optimize the network that has been launched based on the actual statistics instead of on predictions.

Optimization is necessary in several phases of the network evolution. The following dif-ferent methods are used in the different phases:

1. Pre-launch optimization: the aim is to find the best settings for fulfilling the network dimensioning and coverage criteria. This is based on predictions and simulations that have been made before the network is rolled out.

2. Roll-out phase verification: this includes error detection and verification of the initial performance and coverage through the use of field measurements.

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Optimizing and expanding WCDMA RAN overview

3. Operational phase optimization: this takes place when the roll-out has been com-pleted and verified and when the network is carrying subscriber traffic. In this phase, the best results are achieved when the optimization is done based on actual network measurements.

The scope and pace of the pre-launch optimization is determined by the pre-defined network quality and performance targets and the roll-out scope and schedule. The main focus of the pre-launch optimization is on troubleshooting, that is:

1. Locating problem areas2. Prioritizing them3. Fixing them accordinglyThe problem-solving capabilities and processes of the network operator personnel should also be in the scope of pre-launch optimization.

The aim of the operational phase optimization is to maintain network quality and perfor-mance while the complexity of the network environment is multiplied due to additional features and services, as well as network expansions and increased traffic.

For more information, see the following:

Monitoring use cases overview in Monitoring WCDMA RAN Introduction in Dimensioning WCDMA RAN Planning (detailed radio network) configuration in Planning WCDMA RAN Measuring WCDMA RAN in Measuring WCDMA RAN Overview of WCDMA RAN key performance indicators in WCDMA RAN Key Perfor-

mance Indicators

For a full list of parameters, see WCDMA Radio Network Configuration Parameters.

Before you start

Change only one parameter at a time so that the impact of the change on the network can be seen.

Keep track of all of the changes that you make, so that you can restore the network to the previous configuration if the changes have unwanted effects.

Networks are typically optimized in clusters. Since the frequency is the same, the opti-mization should be conducted simultaneously for the whole cluster. Cell-based optimi-zation produces the best performance, but in a homogeneous environment or traffic scenarios it is not significantly better than cluster-based optimization. Cluster-based optimization, however, takes less effort. Clusters that are geographically isolated, for example clusters that are separated by a hill, do not cause excessive interference between each other. In practice, however, the roll-out plan affects the initial selection of clusters.

In the operational phase optimization, pay particular attention to the following:

Interference and noise control (pilot pollution) This exists if the received code power is high but the Ec/I0 is very low. Pilot pollution can be optimized by, for example, reducing the signal of the neighbouring cells and by optimiz-ing the antenna tilts of the neighbouring cells.

Weak coverage Low mobile receiver power leads to degradation of the service quality due to such things as fading, low Ec/I0 or a poor FER. This can be improved by adding a site, adding a better antenna, or adjusting the parameters.

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Call functionality problems For example, call setup fail or call drop.

System performance degradation due to an unbalanced control channel For example, capacity degradation.

Mobility management Handover performance optimization in particular.

Operational phase optimization is an area-wide tuning of parameters based on long-term statistics and trends. Network statistics are usually used to provide information about problem spots. If the problem cannot be solved, field measurements can also be taken into consideration. The aim of this is to identify future problems in traffic areas that are growing quickly in order to react in time and to be prepared for network expansions.

This is done as follows:

Locate the problem spots geographically and by network elements by monitoring the network

Prioritize the actions with the help of KPIs Identify the reasons for the non-performance by analyzing information on the various

statistical indicators and the history of the network

SummaryThe following procedure is an example of radio network optimization.

Steps

1 Agree on a master plan.Decide on the additional services and features that are going to be introduced into the network and the kind of capacity and service area expansions that are going to be made. Consider both the short-term and long-term modifications. This clarifies the targets to be set for the network and gives input for future actions in the plan, for both hardware and software.

2 Set KPIs.After deciding on the long and short-term plans, set targets for the network performance for capacity, coverage and quality. The KPIs are network-specific and depend, for example, on the life stage and needs of the network.

3 Prepare a measurement test plan and tool guidelines.In optimization, two major measurement types can be defined:

a) Drive/field test measurements b) Network management measurements (Nokia Siemens Networks NetAct Frame-

work)

Drive test measurements focus on coverage-related and call-related parameters. The route cannot take more than 1-2 hours to drive, as otherwise the measurement data files become too large and too complicated to be analyzed. The measurement routes should include urban, suburban and rural roads, as well as streets and highways. Special areas should also be included, for example shopping centers and airports. The main focus should be on area types with the tightest requirements for network performance in terms of quality, capacity, and coverage, typically urban regions or traffic hot spots with the

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Optimizing and expanding WCDMA RAN overview

densest penetration of mobile subscribers. The measurement time period must be 3-5 working days and must cover busy hours in the network.

Network management measurements focus on quality. Activate the measurements nec-essary, such as traffic, resource availability, resource access, handover, power control and quality on the RNC-level. This provides the raw counters that are needed to build up key performance indicators on the network management and service management level.

Define the tools that will be used for creating the measurements. Decide how the reports will be presented, including the format and the template used.

4 Run the drive test measurements.Drive according to the pre-defined routes and make several two-minute test calls in the cell cluster area. Store the results in files that are named properly.

g If the network configuration changes, repeat the measurements along the same routes. It is not otherwise possible to compare the results for evaluating potential performance improvements.

5 Run the measurements with NetAct.Before you start

NetAct statistics are not reliable in the early network life stage because of the small number of subscribers. There should be typically at least 50 calls during a busy hour per cell.

Run the measurements on the RNC-level according to the pre-defined list of measure-ments. The raw counters in the NetAct database can be grouped for each network element to build up formulae to describe the network in terms of performance indicators. The performance indicators can be pre-defined or tailored to meet the requirements.

6 Analyze and process the measurements.Use post-processing tools to analyze the network performance.

7 Identify the problems.Check if the resolution database contains descriptions of any similar problems.

8 Find solutions.Before you startTake the following into account:

Missing a site results in non-performance in the area and exclusion zones in accep-tance.

Adding a site later affects the neighbouring sites, and a re-optimization is necessary in the area.

Problems can be solved by either making hardware changes or optimizing parameters.

File all of the optimization actions in the resolution database for future reference.

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The following are examples of different solutions:

Adding or deleting radio network objects:This can be done using the system defaults or a reference site. An additional Base Transceiver Station (BTS) site can be created with a number of cells or additional cells to a given site.When a radio network object is deleted, all objects beneath the object are deleted as well. For example, if you delete a BTS site then all cells under it are also deleted.

Modifying:adjacenciesModifying adjacencies is necessary when BTSs are added or deleted from the network.

RNC split (3G rehosting):RNC split, also known as 3G rehosting, means re-configuring and expanding the network by rehosting a BTS site to another RNC or by adding a BTS under an RNC using an existing site as a reference site. For further information on RNC split/3G rehosting, see Rehosting WCDMA BTS Sites in NetAct Product Documentation.a) Configure the BTS under the target RNCb) Connect the cables from the RNC to the BTSc) Unlock the additional site under the target RNC

Modifying parametersConsider whether the modifications affect the services. If so, plan a date and time for the task and inform the organisation about the plans. If an element has to be locked for modification, it cannot transmit traffic. Plan and prepare for service loss in order to minimise the unavailability of the services.

Expected outcomeThe network should perform within the range expected after optimization.

VerificationVerify the performance against the changes in the network.

Further informationFor information on parameters and counters, see:

Overview of WCDMA RAN key performance indicators in WCDMA RAN Key Per-formance Indicators

WCDMA Radio Network Configuration Parameters RNC Counters - RNW Part Introduction to RNC transport and HW part counters in the RN4.0 release in RNC

Counters - Transport and HW Part Radio network management in Administering Radio Networks AXC countersMore information can also be found in Implementing Parameter Plans for WCDMA, Creating WCDMA BTS sites and Rehosting WCDMA BTS sites in NetAct Product Doc-umentation.

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Principles of optimizing GSM/WCDMA interworking

2 Principles of optimizing GSM/WCDMA inter-workingThe purpose of optimizing GSM/WCDMA interworking is to enhance the effective usage of both GSM and WCDMA networks. In doing so, the largest capacity and coverage possible can be obtained while still maintaining a good Quality of Service.

Optimizing GSM/WCDMA handover means the tuning of the parameters that trigger and make inter-system handovers between GSM and WCDMA possible. When planning GSM/WCDMA interworking, cell re-selection and inter-system handover parameters for GSM and WCDMA were planned. In the optimization phase, these parameters are tuned to meet the needs of the operator.

Handovers from WCDMA to GSM are performed mainly for coverage reasons, whereas handovers from GSM to WCDMA are mainly carried out for load and service reasons. In other words, WCDMA can be used to relieve the GSM overload and GSM to extend the WCDMA coverage area. GPRS calls are switched to WCDMA whenever possible, if so configured.

The compressed mode enables an inter-system handover in WCDMA to be performed. When the UE uses the Uu interface in compressed mode, the contents of the Uu inter-face frame are compressed to open a time window through which the mobile station can peek and decode the GSM Broadcast Control Channel (BCCH) information. In RU10, all dual-mode users in idle mode and call setup phase are kept in the WCDMA. In the call active phase, the following handovers and cell re-selections can be per-formed:

GSM-WCDMA: load-based handover or service-based handover GPRS-WCDMA: network-controlled cell re-selection WCDMA-GSM: coverage-based handover WCDMA-GPRS: coverage-based, network-initiated cell re-selectionFor more information on handovers, see Section WCDMA RAN RRM Handover Control in WCDMA RAN RRM Handover Control .

Coverage-based handoverThe following triggers in the RNC can initiate the coverage-based handover:

Inter-system handover or cell re-selection due to Uplink Dedicated Channel (DCH) quality

Inter-system handover or cell re-selection due to UE Radio Transmitter (UE Tx) power

Inter-system handover or cell re-selection due to Downlink Dedicated Physical Channel (DPCH) power

Inter-system handover or cell re-selection due to Common Pilot Channel, Received Signal Code Power (CPICH RSCP)

Inter-system handover or cell re-selection due to CPICH Ec/No.For information on the parameters that trigger WCDMA-GSM handovers, see WCDMA Radio Network Configuration Parameters. For information on the counters for triggering and the actual performing of each WCDMA-GSM handover, see Section Introduction to RNC transport and HW part counters in RNC Counters - Transport and HW Part.

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Optimizing WCDMA RAN Principles of optimizing GSM/WCDMA interworking

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Load-based handoverOptimize the load-based handover to avoid unnecessary handovers. Take interference from the surrounding cells into account. Set a certain threshold, for example 80%, for the load of a GSM cell. In high load situations, speech calls are directed to the WCDMA to ensure sufficient speech capacity. If the target cell load seems to be high, that is, there are many rejected handovers, set a penalty timer to prevent inter-system handover for a certain time.

Service-based handoverDirect data calls to the WCDMA regardless of the GSM load to ensure higher bit rates for data users and keep speech calls in the GSM, except in high load situations. GPRS calls are shifted to the WCDMA whenever possible.

The idle mode of GPRS mobile stations can be controlled by packet BCCH. This means that the GPRS mobile stations can be pushed into WCDMA in idle mode.

The dedicated mode of GPRS mobile stations can be controlled by network-controlled cell re-selections for load reasons. Inter-system cell re-selections GSM-WCDMA force a particular mobile station into WCDMA, for example for load reasons or in the case of an inter-system directed retry.

For more information, see Section Planning GSM/WCDMA interworking in Planning WCDMA RAN.

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Operation and Management Server

3 Operation and Management ServerOperation and Management Server (OMS) is a Linux OS-based management server that is connected to the Telecommunication Management Network. OMS is used for running measurements, storing measurement data and viewing the results.

OMS is used for making local RNC-level changes, one RNC at a time. Use the Nokia Siemens Networks NetAct Framework for network level changes that are aimed at several RNCs.

Main functions of OMSOMS provides the following:

A platform for different network management applications and tools Redundant and expandible hard disk capacity for storing measurement and config-

uration data as well as, for example, database backups Scalable hardware to support additional applications An easy to use graphical user interface A mediation functionality between DX/IPA2800 network elements and NetAct that

can be used, for example, to filter and buffer the data collected Common network element management tools and interfaces for 2G and 3G network

elementsFor more information, see Section Administrative interfaces in WCDMA RAN Inter-faces.

Performance management in OMSOMS performs the post-processing of the statistics data required for performance man-agement in the RNC. The radio network measurement timing and handling in the RNC is located in OMS, which provides measurement timing, starting and stopping, as well as data handling, storing, and forwarding. For the RNC platform, measurement (ATM and NE performance) handling is located in the network element and OMS performs post-processing for the ATM module data.

The prerequisite for OMS performance management is that the RNC implements a per-formance management function. OMS has the following Graphical User Interfaces (GUIs):

RNW Measurement Management for managing radio network measurements RNW Measurement Presentation for creating graphical and textual presentations of

radio network measurement data NE Measurement Explorer for viewing transmission and NE performance measure-

ment data NE Threshold Management GUI for managing KPIs and threshold monitoring

parameters in the RNC

More information can be found in the OMS documents in this library. See section How to find Operation and Management Server (OMS) documentation in Guide to WCDMA RAN Documentation.

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Optimizing WCDMA RAN Optimization use cases

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4 Optimization use cases

4.1 WCDMA adjacency optimization based on measurementsPurposeThese instructions are used to perform the use case for WCDMA adjacency optimization based on measurements. This can be done by using the NetAct tools, for example, Opti-mizer. For more information, see NetAct Product Documentation.

Perform this use case in the following situations:

When changes have been made in the network and this causes a need for the neighbour cell list to be optimized

When the validity of the adjacency optimization plan needs to be checkedBefore you startCheck the network element software requirements for this use case using the table below.

SummaryCandidates for the neighbour cell list are measured and selected on the basis of set per-formance criteria. Measurements are carried out by rotating cells that have adjacency candidates.

There are different types of adjacencies, depending on the type of cells for which the relationship is defined:

Inter-System Adjacency (ADJG): an adjacency from a WCDMA Cell (WCEL) to a Master BTS

Intra-frequency Adjacency (ADJS): an adjacency between WCELs on the same fre-quency

Inter-frequency Adjacency (ADJI): an adjacency between WCELs on different fre-quencies

The following table gives the basic information on the WCDMA adjacency optimization based on measurements use case.

Network element Release

RNC RN4.0

BTS N/A

AXC N/A

NetAct OSS5.0 CD set 1

SGSN N/A

MSC N/A

MGW N/A

UE N/A

Table 1 Network element software requirements

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Optimization use cases

The KPIs measured for ADJS are:

Soft Handover (SHO) Attempts (M1013C0) SHO Success Ratio (M1013C1/ M1013C0) SHO Average Ec/No Difference (M1013C2/ M1013C3) SHO Average Ec/No (M1013C4/M1013C5) SHO Average RSCP (M1013C6/M1013C7)The KPIs measured for ADJG are:

Inter-system Handover (ISHO) Attempts (M1015C0) ISHO Success Ratio (M1015C1/ M1015C0) Received Signal Strength Indicator (RSSI) (M1015C2/M1015C3) Base Station Identity Code (BSIC) Verification Time (M1015C4/M1015C5) The KPIs measured for ADJI are:

Inter-frequency Handover (IFHO) Attempts (M1014C0) IFHO Success Ratio (RNC_168a or M1014C1/M1014C0) IFHO Average Ec/No (M1014C2/M1014C3) IFHO Average RSCP (M1014C4/M1014C5) The KPIs measured for detected set cells are:

Detected set Average Ec/No (M1028C0/M1028C1) Detected set Average RSCP (M1028C2/M1028C3)Based on these KPIs, Optimizer calculates a share of handover attempts per adjacency (SHO Share for ADJS, ISHO Share for ADJG, and IFHO Share for ADJI) and fitness value to help you to verify the performance of the adjacency.

ID RAN_USE_CASE_OPT_001

Use case name WCDMA adjacency optimization based on measurements

RAN releases All RAN releases

Actors Network planner, operation engineer

Summary An optimized neighbour cell list is produced based on measurements from the network.

Reasons for performing the use case

Changes have been made in the network resulting in a need to optimize the neighbour cell list

The validity of the adjacency optimization plan needs to be checked.

Triggers for service/resource information used

KPIs based on measurement reports 1A and 1C

Limitations and restrictions None

Preconditions The adjacency list to be used has been decided.

Postconditions A new neighbour cell list has been defined based on the measurements.

Table 2 Use case information

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Optimizing WCDMA RAN Optimization use cases

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For information on using Optimizer, see Section Introduction to Optimizer in Optimizer Principles and Section Overview of the procedure in Optimizing a Network Using Opti-mizer in NetAct Product Documentation.

Steps

1 Select the scope of the adjacency creation.

2 Select the adjacency types.ADJS, ADJG, and ADJI add a reference to the parameter descriptions to be optimized. It is recommended that you optimize the ADJSs first.

3 Define the input parameters for the algorithm.Define the criteria on the basis of which adjacencies are created and/or deleted.

4 Check BSIC/BCCH or scrambling code/frequency collisions.

5 Correct any possible collisions.

6 Define whether to have a fixed number or variable number of candidates for each cell.

7 Generate the candidate pool.

8 Verify the pool generated and decide whether to continue to the rotation.

9 Start the cell rotation.Start by defining the time to provision the candidate adjacencies from the pool. Then define the time to get the performance needed to evaluate the adjacency candidates.

10 Check if performance measurements have been retrieved.

11 Repeat steps 9 and 10 until all iterations have been performed.

12 Study the candidate list and modify it if needed.

13 Save the results in a plan.

14 Verify the results in a table format or on a map.This can be done, for example, by displaying the relevant KPIs on the top of the cell dominance area.

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4.2 Soft handover analysis and optimizationPurposeFollow these instructions to perform the use case for Soft handover analysis and optimi-zation. This use case may need to be performed if problematic areas have been found based on cell-level SHO KPIs. Based on cell-to-cell level KPIs, SHO problems can be identified, profiled and corrected manually.

Perform this use case using the NetAct tools. For more information, see NetAct Product Documentation.

Before you startCheck the network element software requirements for this use case using the table below.

SummaryThe following table contains the basic information needed to perform this use case.


RNC All RN releases

BTS N/A

AXC N/A

NetAct All OSS releases

SGSN N/A

MSC N/A

MGW N/A

UE N/A



Use case name Soft handover analysis and optimization


Actors Network planner, operation engineer

Summary Based on cell-to-cell level KPIs, you can identify, profile and manually correct SHO problems


KPIs based on mobile reports

Limitations and restrictions Measurements are not available


Problematic areas were found based on cell-level SHO KPIs.

Preconditions Reliable traffic data is available.

Postconditions Initial adjacencies have been created and their performance can be measured.


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SHO analysis and optimization is based on the following counters/KPIs:

Number of SHO attempts from cell A to cell B, leading to a dropped call (M1013C0 M1013C1)

Total SHO attempts from cell A to cell B (M1013C0) Average Ec/No difference between cell A and cell B (M1013C2/M1013C3) Number of events where a temporary strong cell causes an SHO (Information avail-

able, but not yet an official counter in RAN) Average SHO duration between cell A and cell B (Information available, but not yet

an official counter in RAN) Period of time where cell A and cell B are in the active set simultaneously, cell A

being the controlling cell (Information available, but not yet an official counter in RAN)

Average number of SHO attempts from cell A to cell B per call (Information available, but not yet an official counter in RAN)

Total number of radio link failure messages during an SHO attempt between cell A and cell B (Information available, but not yet an official counter in RAN)

Total time in SHO (Information available, but not yet an official counter in RAN) Total time a cell is in Active Set Size = 1 (Information available, but not yet an official

counter in RAN) Soft Handover Overhead [%] for One Cell or whole RNC (RNC_79b)Steps

1 Select the threshold for the cell level cost function for cells that are performing well and those that are performing badly.

2 Visualise the cell-level SHO KPIs and identify problematic areas.

3 Visualize the cell-to-cell KPIs further for adjacencies to the problematic cells.

4 Modify the CM data necessary to improve the SHO conditions.

5 Verify and save the changes.

6 Provision the changes to the network.

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4.3 Interference analysis for performance and coverage opti-mizationPurposeFollow these instructions to perform the use case for Interference analysis for perfor-mance and coverage optimization. This use case may need to be performed to find out about interference-related problems in the NW in both DL and UL direction.

Perform the use case by using the NetAct tools, for example, Optimizer. For more infor-mation, see NetAct Product Documentation.

This use case allows you to, for example, show and analyze the average noise level on the top of the dominance area and the average uplink load on the cell icon. Depending on whether the cells with high noise are clustered or singular, different conclusions can be drawn and respective measures can be taken.

To analyze load against throughput (efficiency), show a KPI indicating downlink/uplink total traffic or throughput on a dominance area and show Average downlink/uplink load on the cell icon. If a cell has a high load and low traffic, there is a problem with the down-link/uplink.

For interference levels experienced in the cell from the bordering cells that have not been defined as adjacent cells in the adjacent cell list, analyze the cell level Soft Handover (SHO) overhead. Show the KPI on a map, and check the adjacent cell list length. Check the other KPIs for the problem cells.

To check the differences in Cell Common Pilot Channel (CPICH), visualise the CPICH on the dominance area and the Tx power or SHO Overhead in the cell icon.

Before you startCheck the requirements for network element software for this use case by using the table below.

SummaryThe following table gives the basic information on the Interference Analysis use case.


RNC All RN releases

BTS N/A

AXC N/A

NetAct OSS5.0 CD set 1 / OSS5.0 CD set 2

NOTE: Optimizer WCDMA cell pair-level interference analysis is available in OSS5.0 CD set 2.

SGSN N/A

MSC N/A

MGW N/A

UE N/A


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Interference analysis and optimization is based on the following counters/KPIs:

Noise floor of the system [dBm] (RNC_177b) Average Uplink R99 Load [dBm] (RNC_101b) Average R99 Downlink Load [dBm] (RNC_102b) Average HSUPA Uplink Load [dBm] (RNC_1180a) Average HSPA Downlink Load [dBm] (RNC_1181a) Average CPICH Ec/No (WCEL pair) (M1013C4/M1013C5) CPICH RSCP (WCEL pair) (M1013C6/M1013C7) Detected set Average Ec/No (M1028C0/M1028C1) Detected set Average RSCP (M1028C2/M1028C3) Propagation delay (Timing advance during call setup, propagation delay = time dif-

ference between mobile and base station) (M1006C128 .. M1006C148)

For information on using Optimizer, see Section Introduction to Optimizer in Optimizer Principles and Section Overview of the procedure in Optimizing a Network Using Opti-mizer in NetAct Product Documentation.

Steps

1 Display and analyze the interference-related KPIs on a cell level.a) Analyze the cell KPIs and the parameters.

Average uplink load against average noise levelIf a cell has a low load and high noise, this means that there is a problem with the uplink conditions.

Downlink total traffic (or throughput ) against average downlink loadIf a cell has a high load and low traffic, this means that there is a problem with the downlink conditions.


Use case name Interference Analysis


Actors Network planner, performance engineer

Summary Cells receiving high interference are identified.


Low performance Alarms As a regular check


Common measurement report Mobile reports


Preconditions There are measurements available.

Postconditions High interfering cells have been identified and subsequent actions should be taken to reduce the interference.


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CPICH Power against Total DL Tx Power (and/or SHOO)If there are big differences between bordering cells in CPICH Tx Power, find a way to change the CPICH Tx Power.

b) Select the problematic cells/RNCs.c) Check the Scrambling Code re-use for any collisions and make corrections if

needed (Optimizer can be used for this).d) Create a correction plan and provision to the network.

2 Proceed to the cell pair level analysis using Optimizer.a) Fetch IM raw data to Optimizer (downlink measurements).

Fetch the Timing Advance KPI also.b) Create the Interference Matrix.c) Visualize the interference on a map.d) Perform the interference root cause analysis.

3 Identify and remove the man-made interference and/or improve the site installa-tion.To improve the interference situation, check swapped cables, bad connections, shad-owers nearby and so on.

Change downtilts for the cells that are interfering a lot. Change parameters (for example, CPICH Tx Power, Targets for the Max Tx Powers

and offsets). Create new adjacencies.

4 Verify and save the changes.

5 Provision the changes to the network.

6 Verify the changes after provisioning.

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4.4 WCDMA capacity optimizationPurposeFollow these instructions to perform the use case WCDMA capacity visualisation and analysis. This use case can be performed as part of a regular check or because capacity problems have been identified.

Perform this use case by using the NetAct tools. For more information, see NetAct Product Documentation.

Before you startCheck the following:

All of the configuration information needed and the most critical KPIs have been loaded

KPIs can be retrieved from NetAct (the retrieval is a minimum of 5 days). Configura-tion Management (CM) parameters have been retrieved from NetAct Configurator.

SummaryThe following table provides the basic information needed for this use case.

The following list contains the elements and interfaces and the capacity information with which you can investigate them:


Use case name WCDMA capacity visualisation and analysis


Actors Network planner, operations engineer

Summary Some elements/interfaces are selected a NetAct capacity analysis tool is started for the elements/ interfaces with all elements as the scope. A WCDMA capacity analysis tool view is opened and the information needed on elements/ interfaces and their performance/capacity is shown.


Capacity problems have been identified As a regular check

Triggers for used service/resource information

Common measurement report Mobile reports


Preconditions All of the configuration information needed and the most critical KPIs are loaded.

KPIs can be retrieved from NetAct (retrieval is a minimum of 5 days). Configuration Management (CM) parameters have been retrieved from NetAct Configurator.

Postconditions 3G network elements/interfaces and their performance can be seen in the 3G capacity analysis tool visualisation view.


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WCEL/Uu: High-speed Downlink Packet Access (HSDPA), DCH data performance and congestion

WCDMA Base Station (WBTS): Wideband Signalling Processor (WSP) cards for HSDPA

Iub: Asynchronous Transfer Mode, Virtual Channel Connection (ATM VCC) perfor-mance and congestion for HSDPA and DCH data and its capacity

RNC: performance for HSDPA and DCH data capacity Iur: ATM VCC performance and congestion IuPS: ATM VCC performance and congestion 3G SGSN performanceSteps

1 Select the scope of the optimization.

2 Start the measurements for a minimum of five days.Define the KPI groups needed.

3 Analyze the radio capacity after completing the measurements . Check the configuration mis-matches of Power Optimization for HSDPA:

PtxMaxHSDPA [W] PtxTargetHSDPA [W] PtxOffsetHSDPA [W] HSDPA Priority [enum]

Check for performance problems of WCDMA Base Station (WBTS) (Wideband Sig-nalling Processor cards for HSDPA).

Check for performance problems of WCEL/Uu (High-speed Downlink Packet Access (HSDPA), DCH data).

Check for performance problems of the RNC, for example, performance for HSDPA and DCH data capacity. HSDPA Resource Accessibility for NRT Traffic (RNC_605a) HSUPA Resource Accessibility for NRT Traffic (RNC_913a) HSDPA MAC-d Average net throughput at BTS [Mbps] (RNC_606d) HSDPA MAC-d data volume at BTS [Mbit] (RNC_739c) Average NRT DCH DL Throughput [Mbps] (RNC_611b) Average NRT HS-DSCH DL Throughput [Mbps] (RNC_613b) Average Allocated Downlink Dedicated Channel Capacity for Data Calls in Con-

trolling RNC [Mbps] (RNC_165g) Average Allocated Uplink Dedicated Channel Capacity for Data Calls in Control-

ling RNC [Mbps] (RNC_164f) RAB Success Ratio, NRT Services from Network Perspective [%] (RNC_100d) Packet Service Setup Success Ratio (CSSR) [%] (RNC_576d)

Check for performance problems of Iub/Iur, for example, transmission capability. Iub throughput capacity for PS traffic Available Iub transport capacity per HSDPA connection AAl2 connectivity capacity

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AAL2 connection reservation success rate [%] (RNC_602a) AAL2 path average reserved bandwidth [%] (RNC_601a)

4 Solve the problem(s).

5 Save the changes.

6 Visualize the changes.

7 Provision the plan.

8 Verify the changes.

Optimizing WCDMA RANTable of ContentsList of TablesSummary of changes1Optimizing and expanding WCDMA RAN overview2Principles of optimizing GSM/WCDMA interworking3Operation and Management Server4Optimization use cases4.1WCDMA adjacency optimization based on measurements4.2Soft handover analysis and optimization4.3Interference analysis for performance and coverage optimization4.4WCDMA capacity optimization

Optimizing Wcdma Ran

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