Optimization Guidelines - ACCESSIBILITY Ericsson - Rev01

Optimization Guidelines: Accessibility in Ericsson

CONTENTS 1 INTRODUCTION.............................................................................................................................3 2 ACCESSIBILITY..............................................................................................................................4 2.1 Idle Mode..................................................................................................................................................4 2.2 Call Establishment Process.....................................................................................................................4

3 ACCESSIBILITY KPIs (Key Performance Indicators)...................................................................5 3.1 High Level KPIs.......................................................................................................................................5 3.1.1 Call Setup Success Rate - CSSR (%)..................................................................................................................5 3.1.1.1 CS CSSR (%).........................................................................................................................................5 3.1.1.2 PS CSSR (%).........................................................................................................................................5 3.1.1.3 CS CSSR (%) –from P7.1-....................................................................................................................6 3.1.1.4 PS CSSR (%) – from P7.1-....................................................................................................................6 3.1.2 Overall Service Accessibility - OSAC (%).........................................................................................................7

3.2 Medium Level KPIs.................................................................................................................................8 3.2.1 RRC Connection Success Rate (%).....................................................................................................................8 3.2.1.1 RRC Connection Success Rate CS (%).................................................................................................8 3.2.1.2 RRC Connection Success Rate PS (%).................................................................................................8 3.2.2 Iu Signalling Establishment Success Rate (%)....................................................................................................8 3.2.2.1 Iu-CS Signalling Establishment Success Rate (%)................................................................................9 3.2.2.2 Iu-PS Signalling Establishment Success Rate (%)................................................................................9 3.2.3 NAS Signalling Establishment Success Rate (%) –from P7.1-...........................................................................9 3.2.3.1 NAS CS Signalling Establishment Success Rate (%) – from P7.1-......................................................9 3.2.3.2 NAS PS Signalling Establishment Success Rate (%) – from P7.1-......................................................9 3.2.4 (RAB) Establishment Success Rate (%)..............................................................................................................9 3.2.5 Sending Paging Failure Rate (%)......................................................................................................................10 3.2.6 Blocking Probability..........................................................................................................................................10 3.2.6.1 GoS Speech (%)...................................................................................................................................10 3.2.6.2 GoS PS (%)..........................................................................................................................................10

3.3 Failures after Admission Rate (%):......................................................................................................11

4 PERFORMANCE ANALYSIS.......................................................................................................12 4.1 Admission Control.................................................................................................................................12 4.1.1 Admission Policy...............................................................................................................................................12 4.1.2 Resources to be monitored................................................................................................................................13 4.1.2.1 RF Power.............................................................................................................................................13 4.1.2.2 Code Tree Consumption......................................................................................................................13 4.1.2.3 DL and UL ASE..................................................................................................................................13 4.1.2.4 SF Code Limit (Code Hystogram).......................................................................................................13 4.1.2.5 HSDPA and EUL connections Limit...................................................................................................13 4.1.2.6 UL and DL Channel Elements.............................................................................................................13 4.1.3 RRC Admission Blocks.....................................................................................................................................13 4.1.4 RAB Admission Blocks....................................................................................................................................14

4.2 MP Load (High processor Load)..........................................................................................................14 4.3 After Admission.....................................................................................................................................14 4.3.1 Failure after Admission: Iub Congestion.........................................................................................................15 4.3.1.1 Low RRC Success Rate.......................................................................................................................15 4.3.1.2 Low RAB Success Rate.......................................................................................................................15 4.3.2 Failure after Admission: Core Transport Network Congestion.......................................................................15 4.3.3 Failure after Admission: Hardware Usage (Channel Elements)......................................................................16 4.3.4 Failure after Admission: Channelization Codes...............................................................................................16 4.3.5 Failure after Admission: Others.......................................................................................................................16

4.4 Accessibility issues not detected by counters.......................................................................................17 4.4.1 HW Problems in the RBS..................................................................................................................................17 4.4.2 UL Interference.................................................................................................................................................17 4.4.3 RACH misconfiguration....................................................................................................................................17 4.4.4 Cell Unavailability.............................................................................................................................................17 4.4.5 Node Blocking...................................................................................................................................................17

5 REFERENCES...............................................................................................................................18 6 ANNEX I: UE Idle Mode Procedures............................................................................................19 6.1 PLMN Selection and Reselection..........................................................................................................19 6.2 Reading System Information................................................................................................................20 6.3 Cell Selection and Reselection...............................................................................................................21 6.3.1 Cell Selection.....................................................................................................................................................21 6.3.2 Cell Reselection.................................................................................................................................................21 6.3.3 Location/Routing Area Update..........................................................................................................................22 6.3.4 Paging Procedure...............................................................................................................................................23

7 ANNEX II: Call Establishment Procedure....................................................................................24 7.1 Voice Call Establishment ......................................................................................................................24 7.2 PS Data Call Establishment .................................................................................................................24 7.3 Radio Resource Control (RRC) ...........................................................................................................24 7.3.1 RRC connection Request & Setup....................................................................................................................25

7.4 Core Network Negotiation ....................................................................................................................27 7.5 Radio Access Bearer (RAB) Setup and Reconfiguration....................................................................27

1 INTRODUCTION This series of Optimization Guidelines covers all the main topics regarding

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Performance Monitoring & Analysis Configuration settings Troubleshooting Refer to the internal Claro document “Optimization Process” (DEO.OTM.IOP3000), for a summary of 3G WCDMA Radio Access Network Optimization Basics. This specific document focuses on ACCESSIBILITY and its specifics within ERICSSON infrastructure (Release P7.1). Target users for this document are all personnel requiring a detailed description of this process (Accessibility Optimization), as well as configuration managers who require details to control the functions and optimize parameter settings. It is assumed that users of this document have a working knowledge of 3G telecommunications and are familiar with WCDMA.

Document Revision Control Revision Draft 01

Date 13-Nov-2009

Author QCES/Ericsson

Changes First Release of the document Update from P7 to P7.1:

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NAS signalling phase counters added, both to CSSR KPIs and Medium Level KPIs

Corrections/Additions::

01

12-Mar-2010

QCES/Ericsson

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pmNoLoadSharingRrcConnCs/Ps added to CSSR KPIs Iu Signalling connection phase added to CSSR KPIs CS and PS CSSR now correctly expressed in terms of SUM of all CS / PS RAB types Additional formulas for GoS metrics New sections added in Annex for Core Negotiation and RAB Setup and Reconfiguration phases

2 ACCESSIBILITY Accessibility is the ability of a service to be obtained within specific tolerances and other given conditions, when requested by the user. In other words, the ability of a user to obtain the requested service from the system.

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Target is to get a 100% Accessibility, i.e., all users always get the service they request. Poor Accessibility is typically due to some form of congestion (before or after Admission Control?) hardware/software fault (Check ALARMS, Cells Downtime, tickets in REMEDY…) misconfiguration (AUDIT the settings in RNC)

other reasons (for instance, it is also possible that there is some external source of interference (such as a microwave link on the same frequency) affecting the accessibility) Accessibility is to be monitored independently for the different RAB types (e.g. Speech, CS Video, PS Interactive R99, PS Interactive HSDPA, etc.) as in certain situations only one of the RAB types will be affected.

2.1 Idle Mode Accessibility issues may occur related to the UE idle mode behavior. •

The UE in Idle mode performs next 5 main tasks [Refer to ANNEX I for a brief review]: PLMN selection and reselection

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Reading system information (MIB, SIB) Cell selection and reselection

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Location area (LA) and routing area (RA) registration/update Paging procedure Settings should guarantee that the UE in idle mode is always in the best conditions to access the network (i.e., to initiate a Mobile Originated call, MO) and be reached by the network (i.e., to receive a Mobile Terminated call, MT).

2.2 Call Establishment Process Each step in the Call Establishment process should be monitored in order to clearly identify where the accessibility issue is located. For a more complete review of the Call Establishment Process, refer to ANNEX II.

3 ACCESSIBILITY KPIs (Key Performance Indicators) Below the main metrics used for Accessibility Monitoring of a 3G WCDMA/UMTS Network, and their implementation with Ericsson counters.

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Refer to “SMART Documentation” for further details on the actual implementation of these KPIs in the tool, together with the additional considerations regarding: Treatment of zeros in the denominators Cell Reselection during RRC Establishment Phase RRC Redirections (Load Sharing feature) RRC Repetitions Incoming HHO and SRNS Relocations RAB Load Sharing features (Inter-frequency and Directed Retry to gsm)

3.1 High Level KPIs

3.1.1

Call Setup Success Rate - CSSR (%)

This is the first “overall” metric we are considering to monitor Accessibility as a whole. Up to P7.1, this KPI was typically calculated by considering just 2 steps in Call Establishment: RRC Connection Setup and RAB Establishment. They are assumed to be independent processes, and therefore CSSR was hence calculated as product of the Success Rates of each of these 2 phases (described later in section 3.2): CS/PS_CSSR = 100 * CS/PS_RRC_SSR * CS/PS_RAB_ESR where: CS/PS_RRC_SSR = RRC Setup Success Rate (with CS/PS Establishment Causes) = ( # CS/PS RRC Connection Setup Complete / # CS/PS RRC Connection Request) CS/PS_RAB_ESR = RAB Establishment Success Rate (for CS/PS RABs, both R99 and HS) = ( # CS/PS RAB Assignment Complete / # CS/PS RAB Assignment Request) 3.1.1.1 CS CSSR (%) (For CS connection requests) ∑ pmNoRabEstablishSuccess(RAB)   pmTotNoRrcConnectReqCsSucc (RAB)     100 * *  (pmTotNoRrcConnectReqCs - pmNoLoadSharingRrcConnCs)  [ ∑ pmNoRabEstablishAttempt(RAB)] - pmNoDirRetryAtt   (RAB) 

where (RAB) = Speech, Cs64, Cs57 Low value (e.g.