UMTS RAN Performance Trouble Shooting Guidelines – Nokia Accessibility Document Information

UMTS RAN Performance TroubleShooting Guidelines – Nokia AccessibilityNational & Region Performance Engineering

Document Initiated

November 05, 2008

Revision Number 2.2Revision Date August 26, 2009

© Copyright 2008 T-Mobile USA, Inc. All rights reserved.Confidential and proprietary information of T-Mobile USA, Inc. Not for

distribution outside T-Mobile.

UMTS RAN Performance Trouble Shooting Guidelines – Nokia Accessibility

Document InformationThe information in these materials is confidential and proprietary to T-Mobile USA, Inc. These materials are authorized for the use of T-Mobile USA service providers and their employees and agents, solely for the purposes of the agreement under which these materials are provided. The rights granted hereunder constitute a limited, nonexclusive, revocable license and not a transfer of title. Authorized T-Mobile USA service providers and their employees and agents may view, copy or print pages of these materials solely for the purposes set forth herein, but may not otherwise use, modify, copy, print, display, reproduce, distribute, transmit, publish, license, sublicense or createderivative works from these materials in whole or in part, or remove any copyright or other proprietary notices set forth herein, without the express written permission of T-Mobile USA. The information in these materials is subject to change without notice. T-Mobile USA's liability for anyerrors in these materials is limited to the documentary correction of errors. T-Mobile USA will not be responsible in any event for errors in these materials or for any damages, incidental or consequential (including monetary losses), that might arise from the use of these materials or the information in them. T-Mobile, the T-Mobile logo and the World Class logo are registered or unregistered trademarks of Deutsche Telekom AG.

Acknowledgements The following individuals are responsible for contribution to the specifications, design and implementations represented in the various revisions:

Russell Foreman (South)Sanjay Chawla (South)Tim Zhang (FSC)Heitor Almeida (FSC)

Dinesh Kumar (FSC - NSN)Protection of Information Credibility

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Revision Code The revision number will reflect the modifications by following the format Rev. x, y, whereX is the first digit, incremented for changes of substance, i.e. technical/procedural issues.

T-Mobile USA, INC. Confidential Rev. 2.2 August 26, 2009 2 of 45

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Y is the second digit, incremented when editorial only changes have been incorporated.

All draft/preliminary versions are 0.n; the first final version is Revision 1.0.

Revision HistoryRev. Date Author Information1.0 11/05/08 Russell Foreman

Sanjay ChawlaInitial document for Nokia UMTS Phase 1 Trouble Shooting Guideline document for KPI category “Accessibility’.

1.5 1/20/09 Russell Foreman Sanjay Chawla

Revamped document for Nokia Accessibility – includes formulas, counter descriptions, flowcharts, and examples for troubleshooting

1.6 1/28/09 Tim Zhang Re-format the document with standard format1.7 2/5/09 Dinesh Kumar (NSN) Modified on section 2.3.31.8 2/5/09 Sanjay Chawla Updates on section 2.51.9 2/6/09 Tim Zhang Troubleshooting flowchart added in Section

2.22.0 2/13/09 Heitor Almeida Updated the PS NRT Access Failure rate

formula/section including the Rab reconfiguration phase for the rab 0/0, and added section describing the RAB 0/0 kbps Reconfiguration Phase. Excluded HS specific section since PS section is treating both R99 and PS now.

2.1 2/19/09 Heitor Almeida , Dinesh Kumar (NSN)

Updated flowchart and cell analysis for PS setup failure causes for the rab 0/0 reconfiguration phase.

2.2 8/26/2009

Russell Foreman Corrected minor errors and removed copied data from Retainability document paste error. Also updated Tools section



Table of Contents

1. Introduction.............................................................51.1. Purpose & Scope 51.2. Definitions for this Document 5

2. Accessibility............................................................82.1. T-PIM Reports 82.2. Troubleshooting Flowchart 82.3. CS Voice Accessibility 102.3.1. Nokia Accessibility Messaging Diagram (CS and PS R99) 102.3.1.1. RRC Phase 112.3.1.2. RAB Phase 152.3.2. RNC/Market/Region Level Reporting 182.3.3. Cell Analysis 222.3.3.1. RRC Setup Phase Failure Causes 222.3.3.2. RRC Access Phase Failure Causes 232.3.3.3. Voice RAB Setup Failure Causes 242.3.3.4. Voice RAB Access Failure Causes 252.4. R99 PS RAB Accessibility 262.4.1. RNC/Market/Region Level Reporting 272.4.1.1. RRC Phase 272.4.1.2. RAB Phase (0.0 kbps) 282.4.1.3. RAB 0/0 kbps Reconfiguration Phase 292.4.2. Cell Analysis 342.4.2.1. RRC Setup Phase Failure Causes 342.4.2.2. RRC Access Phase Failure Causes 342.4.2.3. PS R99 RAB Setup Phase Failure Causes 342.4.2.4. PS R99 RAB Access Phase Failure Causes 342.4.2.5. Packet Call Setup Failure Causes 35

3. Configuration Management................................................364. Troubleshooting Tools...................................................375. References..............................................................38



1. Introduction1.1.Purpose & Scope

The intent of this document is to provide UMTS Trouble Shooting and Optimization from KPI and Counter perspectives for Nokia Accessibility and provide detailed analysis strategies for identifying reason for the KPI trends and offering guidelines for improving performance by Key Optimization techniques. The KPI/Counters described here are applicable to the RAS6 release of the Nokia UTRAN.This document is not all inclusive and is only intended to provide aquick cook book to understand available for trouble shooting and optimization best practices Guideline Document. For any information not covered here, the NSN NED documentation should be referenced.

1.2.Definitions for this Document

Term or Acronym Definition

3GPPThird Generation PartnershipProject

AS Active Set

BSIC Base Station Identity Code

BTS Base Transceiver Station

CN Core Network

CPICH Common Pilot Channel

DCH Dedicated Channel

DL Downlink

DPCCHDedicated Physical ControlChannel

DPCH Dedicated Physical Channel

DRNC Drift Radio Network Controller

FACH Forward Access Channel




FIFO First In First Out

GERAN GSM EDGE RAN

GSMGlobal System for MobileCommunications

HCS Hierarchical Cell Structure

HSDPA High Speed Data Packet Access

IAF Intra Frequency

IE Information Element

IEF Inter Frequency

IFHO Inter Frequency Handover

Inter-RAT Inter Radio Access Technology

IRAT Inter Radio Access Technology

Iur Interface between two RNC’s

KPI Key Parameter Indicator

LA Location Area

LAI Location Area Indicator

NBAP Node B Application Part

Node B

Logical node responsible forradio transmission and receptionin one or several cells

OCNSOrthogonal Channel NoiseSimulator

PLMN Public Land Mobile Network

RA Routing Area

RAB Radio Access Bearer

RAI Routing Area Indicator

RAN Radio Access Network




RAT Radio Access Technology

RB Radio Bearer

RBSRadio Base Station – anothername for the Node B

RF Radio Frequency

RL Radio Link

RNC Radio Network Controller

RRC Radio Resource Control

RSCP Received Signal Code Power

RSSIReceived Signal StrengthIndicator

SIB System Information Block

SIR Signal to Interference Ratio

TRX Transceiver

TX Transmit

UE User Equipment

UL Uplink

UMTSUniversal MobileTelecommunication Services

UTRANUMTS Terrestrial Radio AccessNetwork

WCDMAWideband Code Division MultipleAccess



2. AccessibilityThe metrics measures user ability to access the mobile network for circuit switched and packet switched calls. The metrics consists of two components RRC and RAB. The RRC part of the equation measures originating and terminating calls. The non-access stratum (signaling) part of the access call flow is not included in this KPI.

2.1.T-PIM Reports The primary T-PIM Reports used for the Accessibility metrics are:

AccessibilityThese reports are explained in detail in the T-PIM Report Documentation.

2.2.Troubleshooting Flowchart The following flowchart may be useful for troubleshooting the voice and ps accessibility issues based on the problem areas.

Flow chart in PowerPoint



2.3.CS Voice AccessibilityFind below the Metric Definition for CS (Voice) Accessibility % as perT-PIM Specs for Nokia -The metrics measures user ability to access the mobile network for circuit switched voice calls. The metrics consists of two Access components of CS call, RRC and RAB. The RRC part of the equation measures Conversational (originating and terminating). The RAB part ofthe equation measures Speech RAB and is pegged on the best cell in theactive set in Serving RNC. The RRC measures Conversational Voice and Data(CSV+CSD) while RAB part measures only Speech for both originating andterminating causes. Formula:Voice Access Failure Rate% = 100 * (1 - RRC_Access_Success_Rate * RAB_Access_Success_Rate)Where RRC_Access_Success_Rate = (Voice Successful Rrc Connection Requests / Voice Attempted Rrc Connection Requests)RAB_Access_Success_Rate = (Voice Successful Rab Establishments / VoiceAttempted Rab Establishments)AndVoice Successful Rrc Connection Requests = ((Moc_Conv_Call_Atts + Mtc_Conv_Call_Atts) - (Rrc_Acc_Rel_Mo_Conv + Rrc_Acc_Rel_Mt_Conv) - (Moc_Conv_Call_Fails + Mtc_Conv_Call_Fails))Voice Attempted Rrc Connection Requests = ((Moc_Conv_Call_Atts + Mtc_Conv_Call_Atts) - (Rrc_Acc_Rel_Mo_Conv + Rrc_Acc_Rel_Mt_Conv) - (Rrc_Att_Rep_Mo_Conv + Rrc_Att_Rep_Mt_Conv)) Voice Successful Rab Establishments = (Rab_Acc_Comp_Cs_Voice)Voice Attempted Rab Establishments = (Rab_Stp_Att_Cs_Voice + Rab_Stp_Fail_Cs_Not_Supp_Par + Rab_Stp_Fail_Cs_Ue_Capa)

2.3.1. Nokia Accessibility Messaging Diagram (CS and PS R99)



Figure 1: Ericsson vs. Nokia counter pegging in the Access phase of the call



Nokia Accessibility contains RRC phase and RAB phase (due to lack of the counter, SRB phase is not counted in Accessibility now). In each of the phase, there is Setup and Access procedure. Setup procedure usually involves the resource allocation in RAN system.

RRC PhaseNote that if a failure which leads to RRC connection release occurs during any RAB phase, both RRC active and RAB (setup, access or active) failure counters are updated with an appropriate cause.

Figure 2: RRC phase and triggering of specific countersThe following details the specific RRC counters pictured in Figure 3.1. RRC setup attempts. 2. RRC setup attempts per setup cause. 3. RRC setup failures due to

o handover control



o admission controlo transport (Transmission)o RNC internalo frozen BTSo BTS o RNTI Allocation failo IuB AAL2 o ICSU overload

4. RRC setup failures per setup cause. 5. RRC setup complete. 6. RRC access failures due to

o radio interfaceo UEo RNC internal

7. RRC access complete. 8. Special reason: RRC active release due to

o SRNC Relocationo Pre-emption

9. RRC active failures due to o Iu interface (transport)o radio interface (synchronization)o BTSo Iur interface (DRNC)o RNC internalo UE

10. RRC active complete.

RRC setup phase fail counters (item 3 from Figure 2)The RRC setup failure counters below include all traffic types, not just CS voice. So, the setup failure count from the following counters will be greater than that of the CS RRC setup attempts – the CS RRC setup successes.

Counter Service

Definition

RRC_CONN_STP_FAIL_HC All RRC connection request rejects dueto handover control entity reporting a failure

RRC_CONN_STP_FAIL_AC All RRC connection request rejects dueto the admission control entity reporting a failure (excluding frozen BTS reason).

RRC_CONN_STP_FAIL_BTS All RRC connection request rejects due



to unsuccessful radio link setup. RRC_CONN_STP_FAIL_TRANS All RRC connection request rejects due

to transport failure. (Includes fails due to AAL2 Iub)

RRC_CONN_STP_FAIL_RNC All RRC connection request rejects dueto RNC internal failure.

RRC_CONN_STP_FAIL_FROZBS

All RRC connection request rejects dueto admission control entity blocking the radio link establishment in order to ensure the setup of high priority calls.

RRC_CONN_STP_FAIL_RNTI_ALLO

All RRC connection request rejects dueto RNTI allocation failure caused by RRMU overload.

RRC_CONN_STP_FAIL_IUB_AAL2

All RRC connection request rejects dueto Iub transport resource shortagebetween RNC and WBTS.

RRC_CONN_STP_FAIL_ICSU_OVERL

All RRC connection request rejects dueto ICSU overload. (Counter not currently loaded into TPIM, pre-RAS 06 load)

* RRC setup fails due to transport errors (T1 slips, DIP errors, etc.), but not due to Iub congestion must be calculated as RRC_CONN_STP_FAIL_TRANS - RRC_CONN_STP_FAIL_IUB_AAL2

RRC access phase fail counters (item 6 from Figure 2)Counter Servic

eDefinition

RRC_CONN_ACC_FAIL_RADIO All RNC does not receive the RRC: RRC CONNECTION SETUP COMPLETE message from the UE within 6 seconds, and theRNC has not received the NBAP messagewhich indicates that L1 synchronization has been established between UE and BTS.

RRC_CONN_ACC_FAIL_MS All RNC does not receive the RRC: RRC CONNECTION SETUP COMPLETE message from the UE within 6 seconds, and theRNC has received the NBAP message which indicates that L1 synchronization has been established



between UE and BTS.RRC_CONN_ACC_FAIL_RNC All RNC internal failure occurs before

receiving the RRC: RRC CONNECTION SETUP COMPLETE message from the UE.

RAB Phase

Figure 3: RAB phase and triggering of counters

Note that RAB active phase is completed also when CN sends RANAP: Iu Release Command.



1. RAB setup attempts. Separate counter per each RAB type. Details in the section RAB setup.

2. RAB setup failures due to (separate counter for each RAB type)o admission controlo transport (transmission)o RNC internalo frozen BTSo BTS (RT only)o anchoring (NRT only)

3. RAB setup complete. Separate counter per each RAB type. 4. RAB access failures due to (separate counters per each RAB

type)o UE o RNC internal

5. RAB access complete. Separate counters per each RAB type.6. Special reason: RAB active release due to (separate counters

per each RAB type)o SRNC relocationo pre-emption

7. RAB active failures due to (separate counters per each RAB type)o Iu interface (transport) o radio interface (synchronization)o BTSo Iur interface (DRNC)o RNC internal o UE.

8. RAB reconfiguration attempts.9. RAB reconfiguration failures.10. RAB active complete. Separate counters per each RAB type.

RAB setup phase fail counters (item 2 from Figure 3)Counter Service Definition

RAB_STP_FAIL_CS_VOICE_AC CS (Voice)

RNC rejects the CS voice RAB request because the admission control entity reports a failure(excluding frozen BTS reason).

RAB_STP_FAIL_CS_VOICE_BTS CS (Voice)

RAB assignment fails due to radio link setup or



reconfiguration failure. The failure can happen either in theIub or in the Iur interface.

RAB_STP_FAIL_CS_VOICE_TRANS

CS (Voice)

RNC rejects the CS voice RAB request due to transport failure. (Includes fails due to AAL2 Iub)

RAB_STP_FAIL_CS_VOICE_RNC CS (Voice)

RNC decides to reject the CS voice RAB request due to RNC internal failure.

RAB_STP_FAIL_CS_VOICE_FROZBS

CS (Voice)

RNC rejects the CS voice RAB request because the admission control entity blocks the radio link establishment to ensure thesetup of high priority calls.

RAB_STP_FAIL_CS_V_IUB_AAL2

CS (Voice)

RNC decides to reject the CS voice RAB request due to Iub transport resource shortage between RNC and WBTS.

RAB_STP_FAIL_CS_NOT_SUPP_PAR

CS (Voice)

CS RAB setup attempt is not started due to requested parameters are not supported by the RNC. (CS data calls)

RAB_STP_FAIL_CS_UE_CAPA CS (Voice)

CS RAB setup attempt is not started due to requested parameters are not supported by the UE. (CS Data calls)

RAB access phase fail counters (item 4 from Figure 4)Counter Service Definition

RAB_ACC_FAIL_CS_VOICE_MS CS (Voice)

RAB access setup for a CS Voice Call fails because of the UE.

RAB_ACC_FAIL_CS_VOICE_RNC

CS (Voice)

RAB setup access failures for CSVoice Calls caused by RNC's internal reasons.



2.3.2. RNC/Market/Region Level ReportingThis section covers analysis of Accessibility % for Nokia and identification of issues using the available Nokia accessibility Counters.

AtlantaIn the analysis, data for Atlanta from the South region has been presented. The following charts clearly indicates the following

Atlanta Market has three RNCs and has daily traffic of around 5,500 Erlangs for the timeframe under consideration.

The majority of days show that RRC Failure rate is the highest contributing factor to the Total Accessibility score

G1 launch elevated traffic and call setup attempts RNC2 and RNC3 had incorrect RNC level parameters for Iur parameter,

AAL2 CPS-SDU multiplexing delay. One RNC end point had 10 ms,while the other RNC’s end point had 100 ms.

Accessibility was impacted due to this incorrect Iur parameter and the elevated traffic from the G1 launch

Parameter was fixed on Oct 28, 2008 Problem also impacted SHO failure rate and MOU/drop negatively.

Atlanta Accessibility

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Voice Access Failure rate (% ) Conversational RRC Failure Rate (% ) Voice RAB Failure Rate (% ) Voice Access Failures (RRC+RAB)



Figure 4: Atlanta's accessibility mostly influenced by RAB FailuresThe G1 launch increased traffic in ATRNC002 and ATRNC003 tremendously. It highlighted a problem not seen before the G1 launch.

Atlanta Accessibility RRC vs. RAB Fails

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Figure 5: Raw counts of RRC and RAB FailuresRAB Failures increased disproportionally as the G1 launch increased RAB attempts across the Iur interface. Whereas before the G1 launchthe volume of RAB attempts across the Iur boundaries was not sufficient to reveal the issue.

Atlanta Accessibility - M obile Term inated vs M obile O riginated Call Fails

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Figure 6: Atlanta shows mobile originated calls as having the worst problem in Access FailsNo real change in the RRC fail reasons of terminated calls as opposed to originating calls. Mobile originated calls bear a greater percentage of failures over mobile terminating call.

Atlanta Accessibility - RAB Setup Fail Reasons

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% RAB_STP_FAIL_CS_VOICE_AC % RAB_STP_FAIL_CS_VOICE_BTS % RAB_STP_FAIL_CS_VO ICE_RNC % RAB_STP_FAIL_CS_VO ICE_FRO ZBS% RAB_STP_FAIL_CS_V_IUB_AAL2 % RAB_STP_FAIL_CS_NOT_SUPP_PAR % RAB_STP_FAIL_CS_UE_CAPA % RAB_STP_FAIL_CS_V_Trans(not Iub)

Figure 7: In RAB Setup phase, the majority of Atlanta’s problems arein the non Iub transport and the RNC level reasons for access failuresWhen the Iur parameter mismatch was fixed, there is an immediate decrease in the transport related RAB setup fails on Oct. 28.



Atlanta Accessibility - RAB Access Fail Reasons UE vs. RNC

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Figure 8: RAB access fail reasons show the UE as being the weak linkwhich is more an indication of RF conditions rather than the UE being faulty

No major impacts on RAB access fail reasons of the UE as opposed to the RNC relating to this Iur problem.

Atlanta Accessibility - RRC connection setup fail reasons

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Figure 9: RRC connection setup fails in Atlanta for the most part isdominated by RNC errors with some contribution from Access Control and BTS errorsThe increase in IUB AAL2 (blocking in the Iub reservations) RRC setup fails can be seen starting mainly on 10/20 which corresponds



to the launch of the G1. This fail metric is starting to dominate the RRC setup failures. The solution is to start adding Iub capacity and to utilize more Iub saving features where additional capacity is not feasible.

Atlanta Accessibility - RRC Access Fail Reasons

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08

%

% RRC_CONN_ACC_FAIL_RADIO % RRC_CONN_ACC_FAIL_M S % RRC_CO NN_ACC_FAIL_RNC

Figure 10: RRC Access fails show the RF conditions are the majority of the problems reside in the radio link for Atlanta

2.3.3. Cell Analysis

RRC Setup Phase Failure CausesPlease note all these RRC failure counters for all type of services or establishment causes (not just voice).

a) RRC Request Reject due to Handover ControlWhen the RNC decides to reject the RRC connection request because the handover control entity reports a failure. Identify, if the problem is RNC wide or spread over a group of cells and report to tier 2 for further investigation.

b) RRC Request Reject due to Admission Control



The RNC will check the available resources during the RRC setup stage;DL Codes, UL Load (Prx total), DL load (Downlink Tx power). (Note the RNC does not check for CE in the NodeB)Detailed analysis can be done to find exactly which resource is causing the admission problem from traffic and cell resource counters.

c) RRC Request Reject due to Transport Failure (include failure due to AAL2)

Transport failures are mostly due to T1 related issues which can be checked from BER counters. This counter will also include the number of times the T1 was congested (AAL2 blocking).Detailed analysis can be done from AAl2 resource reservation counters.

d) RRC Request Reject due to RNC Internal Failure

This counter is pegged if the RNC can not assign the failure to any other failure counters or if there is a RNC hardware/software/resourceproblem/L2 failure. This counter needs to be monitored for any step changes for it might indicate RNC is having some internal problem likehanging resources.

e) RRC Request Reject due to Frozen BTS

This counter pegs in the event when the RNC rejected the RRC setup to ensure the setup of high priority calls. This is related to congestion& should be analyzed as per RRC Request Reject due to Admission Control

f) RRC Request Reject due to RNTI Allocation FailureThis counter point out resource issues in the RRMU. Investigate RNC dimensioning. g) RRC Request Reject due to Iub AAL2 Transport This counter points out T1 capacity problems between RNC and NodeB..



Before a T1 upgrade is raised for cells having a high count in Iub congestion a detail analysis must be done to investigate if the congestion can be resolved by improving the Soft Handover Overhead (bydown tilt or parameter change).Detailed analysis can be done from AAl2 CAC/ resource reservation counters.

h) RRC Request Reject due to ICSU OverloadIt is unlikely that this will be a cell specific issue and would rather be an RNC wide or multiple sites connected to the ICSU. There is a few know problems in the RNC that are related to the ICSU load and dimensioning issues, see “List of Generic Faults LGF-RNC-2008-07 Radio Controllers WCDMA RNC RN2.2, RN3.0” on NED for more details.

i) RRC Request Reject due BTSThis counter is showing that there is potentially a hardware, configuration or resource issue in the NodeB.Resource problems can be verified from the CE usage counters, if the traffic is low and the CE usage is high it is due to hanging resources. If the traffic is high it might be that there is not enoughlicense keys for CE. (Compare the max CE used counters with installed license keys in the WBTS) Also check the number of users in CompressedMode, currently defined as maximum of 16 with the T-Mobile USA baseline parameter set. If the number of users in compressed mode is high when there is no traffic in the cell it is also indicates that there is hanging resources in the cell.

A site reset normally corrects these problems, if the problem does notclear or repeats a ticket should be open with the field technicians toinvestigate. Potential issues on the site that can cause this problemcan be:

Incorrect configuration data (audit the commissioning file for any discrepancies)

Corrupt files in the NodeB (Recommissioning should resolve this problem)

Corrupt software in the NodeB (Software upgrade/ downgrade can beused to reload the software in the site)

Faulty hardware (System module). It has been seen that replacing the system module resolved this problem. Note in these instances there were no alarms on the site to indicate that there was a hardware issue.



RRC Access Phase Failure Causes

a) RRC Connections Access Failure due to Radio ReasonsThese failures are mostly RF related and can be split between:

Bad Coverage (Low RSCP) Interference (Low Ec/No)

Route cause analysis will in most cases require drive test analysis.Also verify that the uplink PRXnoise for these sites is within acceptable range.

b) RRC Connections Access Failure due to MS FailuresThe cause for this counter can be coverage even though L1 synchronization has been achieved it can still be that a sudden lossin coverage was experienced. If only one site is showing a high count for this counter the most likely cause is that it is coverage related. If this is an RNC wide problem it needs to be determine if it is a specific UE type that is causing the problem, this will require advance analysis with the help of K18 and potentially the Xmine team. Also verify that the uplink PRXnoise for the site is within acceptable range.

c) RRC Connections Access Failure due to RNC FailuresIf the counter is showing a step change it might be related to a newsoftware load that was loaded on the RNC or core network side. To trouble shoot these problem it will require in-depth analysis on theRNC which should be done by Tier 2. If only particular sites are showing a high count for this counter investigate if there is any common point of failure for these cells ( Same RNC, same Transmission path/ hardware) Also investigate if the T1 for these sites are error free ( Look at the cell availability and BER for T1)

Voice RAB Setup Failure Causesa) Voice RAB Setup Failure Due to Admission Control



Same as RRC admission control (2.3.3.1) only difference is that now the exact number of voice attempts rejected due to admission can be seen rather than the total for all the services.

b) Voice RAB Setup Failure Due to BTSSame as RRC setup failures due to BTS (2.3.3.1)

c) Voice RAB Setup Failure Due to Transport (includes failures due to AAL2 Iub)Same as RRC setup failures due to Transport (2.3.3.1)

d) Voice RAB Setup Failure Due to RNCSame as RRC setup failures due to RNC (2.3.3.1)

e) Voice RAB Setup Failure Due to Frozen BTSSame as RRC setup failures due to Frozen BTS (2.3.3.1)

f) Voice RAB Setup Failure Due to AAL2 IubSame as RRC setup failures due to AAL2 (2.3.3.1)

g) Voice RAB Setup Failure Due to Non-support RequestCS RAB setup attempt is not started due to requested parameters are not supported by the RNC. (CS data calls) It should be looked into if this is a specific device that is requesting the unsupported RAB configuration, this investigation can only be done with the help of K18 or similar advance tracing equipment.

h) Voice RAB Setup Failure Due to UE CapabilitySame as above, voice RAB Failure Due to Non-supported Request.

Voice RAB Access Failure Causesa) Voice RAB Access Failure Due to UE

Same as RRC access failures due to MS (2.3.3.2)



b) Voice RAB Access Failure Due to RNC Internal FailuresSame as RRC setup failures due to RNC (2.3.3.1)



2.4. R99 PS RAB AccessibilityFind below the Metric Definition for PS (Packet) Accessibility as per T-PIM Specs for Nokia PS NRT Access Failure Rate (%)The metrics measures user ability to access the mobile network for PS, both HSPA and R99, interactive and background connections. The metrics consists of three components of PS Access call, RRC, RAB andRAB 0/0 reconfiguration.

Figure 11 Three phases considered in the PS Access Failure formulaThe RRC part of the equation measures RRC failures for both originating and terminating calls. The RAB part of the equation



measures failures for the PS NRT RAB 0/0 kbps both originating and terminating and is pegged on the best cell in the active set in Serving RNC. The RAB 0/0 reconfiguration part measures the failures when trying to actual reserve resources to reconfigure the RAB 0/0 and assign it certain bit rate.The non-access stratum (signaling) and PDP access part of the accesscall flow is not included in this KPI.Formulas:PS NRT Access Failure Rate (%) = 100*(1-(Ps Successful RRC Connection Requests / Ps Attempted RRC Connection Requests) * (Ps Successful RAB Establishments / Ps Attempted RAB Establishments) * (Packet Call Allocation Success/Packet Call Attempts)) Where:Ps Successful Rrc Connection Requests = (Moc_Inter_Call_Atts + Mtc_Inter_Call_Atts + Moc_Backg_Call_Atts + Mtc_Backg_Call_Atts) - (Rrc_Acc_Rel_Mo_Interactive + Rrc_Acc_Rel_Interactive + Rrc_Acc_Rel_Mo_Background + Rrc_Acc_Rel_Mt_Background) - ( Moc_Inter_Call_Fails+Mtc_Inter_Call_Fails + Moc_Backg_Call_Fails+ Mtc_Backg_Call_Fails )Ps Attempted Rrc Connection Requests = (Moc_Inter_Call_Atts + Mtc_Inter_Call_Atts + Moc_Backg_Call_Atts + Mtc_Backg_Call_Atts) - (Rrc_Acc_Rel_Mo_Interactive + Rrc_Acc_Rel_Interactive + Rrc_Acc_Rel_Mo_Background + Rrc_Acc_Rel_Mt_Background) - (Rrc_Att_Rep_Mo_Interactive + Rrc_Att_Rep_Interactive + Rrc_Att_Rep_Mo_Background + Rrc_Att_Rep_Mt_Background)Ps Successful Rab Establishments = Rab_Acc_Comp_Ps_Inter + Rab_Acc_Comp_Ps_Backg Ps Attempted Rab Establishments = Rab_Stp_Att_Ps_Inter + Rab_Stp_Att_Ps_BackgPacket Call Allocation Success = Hs_E_Req_Hs_E_Allo_Int + Hs_E_Req_Hs_E_Allo_gr + Hs_E_Req_Hs_D_Allo_Int + Hs_E_Req_Hs_D_Allo_Bgr + Hs_D_Req_Hs_D_Allo_Int + Hs_D_Req_Hs_D_Allo_Bgr + Hs_E_Req_D_D_Allo_Int + Hs_E_Req_D_D_Allo_Bgr + Hs_D_Req_D_D_Allo_Int + Hs_D_Req_D_D_Allo_Bgr + D_D_Req_D_D_Allo_Int + D_D_Req_D_D_Allo_Bgr Packet Call Attempts = Ps_Att_Hsdsch_Edch_Int+Ps_Att_Hsdsch_Edch_Bgr + Ps_Att_Hsdsch_Dch_Int + Ps_Att_Hsdsch_Dch_Bgr + Ps_Att_Dch_Dch_Int +Ps_Att_Dch_Dch_Bgr



2.4.1. RNC/Market/Region Level Reporting

RRC PhaseSame RRC phase signaling diagram is used for both Voice and R99 PS RRC phase. Please refer to section 2.3.1.1.

RRC setup phase fail counters Same RRC setup phase failure cause counters are applied for both Voice and PS R99 service. Please refer to section 2.3.1.1 for detail.

RRC Access phase fail counters Same RRC Access phase failure cause counters are applied for both Voice and PS R99 service. Please refer to section 2.3.1.1 for detail. In addition, there are a few more RRC Access failure counters available for PS only.

Counter Service DefinitionRRC_ACC_REL_MO_INTERACTIVE

PS Number of RRC connection access releases due to cell reselectionfor calls established with the cause originating interactive call

RRC_ACC_REL_INTERACTIVE PS Number of RRC connection access releases due to cell reselectionfor calls established with the cause terminating interactive call

RRC_ACC_REL_MO_BACKGROUND

PS Number of RRC connection access releases due to cell reselectionfor calls established with the cause originating background call

RRC_ACC_REL_MT_BACKGROUND

PS Number of RRC connection access releases due to cell reselectionfor calls established with the cause terminating background call



RAB Phase (0.0 kbps)

RAB setup phase fail counters (item 2 from Figure 4)Counter Service Definition

RAB_STP_FAIL_PS_CONV_AC PS R99 Conv/stream

RAB setup failures due to rejection of the PS data conversational RAB request because the admission control entity reports a failure (excluding frozen BTS reason)

RAB_STP_FAIL_PS_CONV_BTS PS R99 Conv/stream

RAB assignment fails due to radio link setup or reconfiguration failure. The failure can happen either in the Iub or in the Iur interface.

RAB_STP_FAIL_PS_CONV_TRANS

PS R99 Conv/stream

RAB setup failures caused by transport for PS data conversational.

RAB_STP_FAIL_PS_CONV_RNC PS R99 Conv/stream

RAB setup failures caused by RNC internal failure for PS data conversational.

RAB_STP_FAIL_PS_CONV_FROZBS

PS R99 Conv/stream

When the RNC decides to reject the PS data conversational RAB request because the admission control entity blocks the radiolink establishment to ensure the setup of high priority calls

RAB_STP_FAIL_PS_INTER_AC PS R99 Inter

RAB setup failures due to rejection of the PS data interactive RAB request becausethe admission control entity reports a failure (excluding frozen BTS reason)

RAB_STP_FAIL_PS_INTER_RNC PS R99 Inter

RAB setup failures caused by RNC internal failure for PS data interactive.

RAB_STP_FAIL_PS_INTER_FROZBS

PS R99 Inter

When the RNC decides to reject the PS data interactive RAB request because the admission control entity blocks the radio



link establishment to ensure the setup of high priority calls

RAB_STP_FAIL_PS_INTER_ANCH

PS R99 Inter

Number of RAB setup failures caused by anchoring for PS datainteractive

RAB_STP_FAIL_PS_BACKG_AC PS R99 Backg

RAB setup failures due to rejection of the PS data background RAB request because the admission control entity reports a failure (excluding frozen BTS reason)

RAB_STP_FAIL_PS_ BACKG _RNC

PS R99 Backg

RAB setup failures caused by RNC internal failure for PS data background.

RAB_STP_FAIL_PS_ BACKG _FROZBS

PS R99 Backg

When the RNC decides to reject the PS data background RAB request because the admission control entity blocks the radiolink establishment to ensure the setup of high priority calls

RAB_STP_FAIL_PS_ BACKG _ANCH

PS R99 Backg

Number of RAB setup failures caused by anchoring for PS databackground

RAB access phase fail counters (item 4 from Figure 4)Counter Service Definition

RAB_ACC_FAIL_PS_CONV_MS PS R99 Conv/steam

RAB access setup for a PS conversational Call fails because of the UE.

RAB_ACC_FAIL_ PS_CONV_RNC

PS R99 Conv/stream

RAB setup access failures for PSconversational Calls caused by RNC's internal reasons.

RAB_ACC_FAIL_PS_INTER_MS

PS R99 Inter

RAB access setup for a PS Interactive Call fails because of the UE.

RAB_ACC_FAIL_PS_INTER_RNC

PS R99 Inter

RAB setup access failures for PSInteractive Calls caused by RNC's internal reasons.



RAB_ACC_FAIL_ PS_BACKG_MS

PS R99 Backg

RAB access setup for a PS background Call fails because ofthe UE.

RAB_ACC_FAIL_ PS_ BACKG_RNC

PS R99 Backg

RAB setup access failures for PSbackground Calls caused by RNC'sinternal reasons.

RAB 0/0 kbps Reconfiguration Phase

In NSN, for non-real time (NRT) services, the radio access bearers(RAB) are initially created without immediate reservation of radioresources (RAB 0/0 kbps). Instead, radio resources are allocatedafter that, based on the capacity requests (event 4A). Therefore theHS and R99 resources are only verified during the attempt toreconfigure the RAB 0/0 to a certain bit rate different than 0/0.

The packet call attempts measured in this kpi are updated when theUE-specific packet scheduler attempts to allocate an HS-DSCH/E-DCH,HS-DSCH/DCH or DCH/DCH transport channels for the NRT RAB that hasno dedicated/shared channels that are already allocated for the RAB(RAB 0/0). So only RAB 0/0 kpbs to higher bit rate RAB or FACH toDCH channel switches are computed. Packet call channel switches fromRAB>0/0 kbps to higher or lower bit rate are not considered in thisKPI.Below is the formula for the RAB Reconfiguration component of theheadline PS Access Failure Rate metric.

Packet Call Allocation Failure Rate (%) = 100*(1- (Packet Call Allocation Success/Packet Call Attempts)) Where,Packet Call Allocation Success = Hs_E_Req_Hs_E_Allo_Int + Hs_E_Req_Hs_E_Allo_gr + Hs_E_Req_Hs_D_Allo_Int + Hs_E_Req_Hs_D_Allo_Bgr + Hs_D_Req_Hs_D_Allo_Int + Hs_D_Req_Hs_D_Allo_Bgr + Hs_E_Req_D_D_Allo_Int + Hs_E_Req_D_D_Allo_Bgr + Hs_D_Req_D_D_Allo_Int + Hs_D_Req_D_D_Allo_Bgr + D_D_Req_D_D_Allo_Int + D_D_Req_D_D_Allo_Bgr Packet Call Attempts = Ps_Att_Hsdsch_Edch_Int+Ps_Att_Hsdsch_Edch_Bgr + Ps_Att_Hsdsch_Dch_Int + Ps_Att_Hsdsch_Dch_Bgr + Ps_Att_Dch_Dch_Int +Ps_Att_Dch_Dch_Bgr



The formula considers the user point of view in terms that as longas the customer gets the data service access, it is considered asuccessful allocation. For example, if the transport channelallocation request was for HS-DSCH/DCH - HSDPA on the downlink andR99 on the uplink (counter Ps_Att_Hsdsch_Dch_Bgr) - and the actualallocation was DCH/DCH - R99 on both downlink and uplink (counterHs_D_Req_D_D_Allo_Bgr ) - , it is still considered a successfulaccess since the user got the data service anyway.The figure below shows the possible types of packet allocationrequests and their respective successful allocations types. Thereare counters for each of them.

Below is the description of all the counters used on the RAB 0/0kbps Reconfiguration Phase part of the ps access failure metric.

Counter Description Condition MO Class

PS_ATT_HSDSCH_EDCH_INT

PS_ATT_HSDSCH_EDCH_BGR

The number of HS-DSCH/E-DCH packetcall attempts forthe interactive

Updated: When the UE-specific packet scheduler attempts to allocate an HS-

Packet Call (M1022)




or background traffic class.

DSCH/E-DCH transportchannel for the NRT RAB, and there are no dedicated/shared channels that are already allocated for the RAB.

PS_ATT_HSDSCH_DCH_INT

PS_ATT_HSDSCH_DCH_BGR

The number of HS-DSCH/DCH packet call attempts forthe interactive or background traffic class.

Updated: When the UE-specific packet scheduler attempts to allocate an HS-DSCH/DCH transport channel for the NRT RAB, and there are no dedicated/shared channels that are already allocated for the RAB.

Packet Call (M1022)

PS_ATT_DCH_DCH_INT

PS_ATT_DCH_DCH_BGR

The number of DCH/DCH packet call attempts forthe interactive or background traffic class.

Updated: When the UE-specific packet scheduler attempts to allocate a DCH/DCH transport channelfor the NRT RAB, andthere are no dedicated/shared channels that are already allocated for the RAB.

Packet Call (M1022)

HS_E_REQ_HS_E_ALLO_INT

HS_E_REQ_HS_E_ALLO_BGR

The number of allocations for the HS-DSCH/E-DCHafter an HS-DSCH/E-DCH request for the interactive or background traffic class.

Updated: When the user's HS-DSCH/E-DCHuser plane allocation is successfully completed.

Packet Call (M1022)

HS_E_REQ_HS_D_ALLO_INT

HS_E_REQ_HS_D_ALLO_BGR

The number of HS-DSCH/DCH allocations afteran HS-DCSH/E-DCH

Updated: When the user is successfullyallocated to the HS-DSCH/DCH user plane

Packet Call (M1022)




request for the interactive or background traffic class.

and the request was for the HS-DSCH/E-DCH.

HS_D_REQ_HS_D_ALLO_INT

HS_D_REQ_HS_D_ALLO_ BGR

The number of HS-DSCH/DCH allocations afteran HS-DSCH/DCH request for the interactive or background traffic class.

Updated: When the user is successfullyallocated to the HS-DSCH/DCH user plane and the request was for the HS-DSCH/DCH.

Packet Call (M1022)

HS_E_REQ_D_D_ALLO_INT

HS_E_REQ_D_D_ALLO_ BGR

The number of DCH/DCH allocations afteran HS-DSCH/E-DCH request for the interactive traffic class.

Updated: When the user is successfullyallocated to the DCH/DCH user plane and the request was for the HS-DSCH/E-DCH.

Packet Call (M1022)

HS_D_REQ_D_D_ALLO_INT

HS_D_REQ_D_D_ALLO_ BGR

The number of DCH/DCH allocations afteran HS-DSCH/DCH request for the interactive traffic class.

Updated: When the user is successfullyallocated to the DCH/DCH user plane and the request was for the HS-DSCH/DCH.

Packet Call (M1022)

D_D_REQ_D_D_ALLO_INT

D_D_REQ_D_D_ALLO_ BGR

The number of DCH/DCH allocations aftera DCH/DCH requestfor the interactive or background traffic class.

Updated: When the user is successfullyallocated to the DCH/DCH user plane and the request was for the DCH/DCH.

Packet Call (M1022)

If the PS user plane allocation fails due to some reason, the corresponding packet call setup failure counters are updated. The following setup failures are seen with these counters:

Admission Control (AC) failures BTS failures DMPG resource allocation failures Iub transport failures



Failures due to UE Any other failures not covered by the other failure counters


PS_SETUP_FAIL_AC_INT

PS_SETUP_FAIL_AC_BGR

The number of packet call setupfailures due to the admission control for the interactive or background traffic class.

Updated: When the PSuser plane allocation is rejected by the admission control.

Packet Call (M1022)

PS_SETUP_FAIL_BTS_INT

PS_SETUP_FAIL_BTS_ BGR

The number of packet call setupfailures due to the BTS for the interactive or background traffic class.

Updated: When the PSuser plane allocation fails dueto the BTS responding with an NBAP: RADIOLINK SETUP FAILURE or an NBAP: RADIO LINK RECONFIGURATIONFAILURE message, or not responding at all.

Packet Call (M1022)

PS_SETUP_FAIL_DMCU_INT

PS_SETUP_FAIL_DMCU_ BGR

The number of packet call setupfailures due to lack of DMCU resources for theinteractive or background traffic class.

Updated: When the PSuser plane allocation fails dueto a DMCU resource allocation failure.

Packet Call (M1022)

PS_SETUP_FAIL_TRANS_INT

PS_SETUP_FAIL_TRANS_ BGR

The number of packet call setupfailures due to transport for theinteractive or background traffic class.

Updated: When the PSuser plane allocation fails dueto an Iub transport setup failure.

Packet Call (M1022)

PS_SETUP_FAIL_UE_INT

PS_SETUP_FAIL_UE_ BGR

The number of packet call setupfailures due to the UE for the

Updated: When the PSuser plane allocation fails dueto the UE responding

Packet Call (M1022)




interactive or background traffic class.

with an RRC: RADIOBEARER RECONFIGURATION FAILURE message or not responding at all.

PS_SETUP_FAIL_OTHER_INT

PS_SETUP_FAIL_OTHER_ BGR

The number of packet call setupfailures for the interactive or background traffic class dueto other reasons than those covered by the other failure counters.

Updated: When the PSuser plane allocation fails dueto any other reason not covered by the other failure counters.

Packet Call (M1022)

Below is a snapshot of the current distribution per market of the packet call setup failure counters described above.



2.4.2. Cell Analysis

RRC Setup Phase Failure CausesThe PS RRC Setup Phase Failure Causes are same as Voice. Please refer to section 2.3.3.1 for detail.

RRC Access Phase Failure CausesThe PS RRC Access Failure due to Radio Reason, UE or RNC is same as Voice. Please refer to section 2.3.3.2 for detail.

PS R99 RAB Setup Phase Failure Causes

a) PS R99 RAB Setup Failure Due to Admission ControlSame as RRC admission control (2.3.3.1)

b) PS R99 RAB Setup Failure Due to BTS Failure



Same as RRC setup failures due to BTS (2.3.3.1)

c) PS R99 RAB Setup Failure Due to TransportSame as RRC setup failures due to Transport (2.3.3.1)

d) PS R99 RAB Setup Failure Due to RNCSame as RRC setup failures due to RNC (2.3.3.1)

e) PS R99 RAB Setup Failure Due to Frozen BTSSame as RRC setup failures due to Frozen BTS (2.3.3.1)

f) PS R99 RAB Setup Failure Due to Anchoring for PS Data Background This happens when NRT RAB setup requested, but NRT RAB is not allowed during anchoring

PS R99 RAB Access Phase Failure Causes

a) PS R99 RAB Access Failure Due to UESame as RRC access failures due to MS (2.3.3.2)

b) PS R99 RAB Access Failure Due to RNC Internal FailuresSame as RRC setup failures due to RNC (2.3.3.1)

Packet Call Setup Failure Causes

a) Packet Call Setup Failure due to Admission Control (AC)In case the starting state of the terminal is Cell_FACH (Cell_PCH) or DCH 0/0 and AC rejects the bit rate allocation and the terminal stays at same state. This scenario will trigger this counter. Check RRC admission control section (2.3.3.1- b) for more details on AC failures.

b) Packet Call Setup Failure due to BTS



This is mainly caused by CE shortage or no response from BTS. Check RRC admission control section (2.3.3.1-i) for more details on BTS failures

c) Packet Call Setup Failure due to DMPG resource allocationThis is mainly caused by lack of DMCU resources. Check the DSP performance measurements in RNC or report to tier 2 as there might be an issue with the DMCU capacity or the HW in the RNC. If the failures are high then it will require in-depth analysis on the RNC which should be done by Tier 2.

d) Packet Call Setup Failure due to Iub transportThese failures are mainly caused by lack of IuB resources (T1). Detailed analysis can be done from AAl2 CAC/ resource reservation counters. If T1 is loaded then see the possibility of activating some additional features or modifying parameters otherwise follow the T-Mobile process to trigger the additional T1.

e) Packet Call Setup Failure due to Failures due to UEThis happens when UE doesn’t respond to RB reconfiguration message or reports a failure. For more detail please refer to section 3.3.3.2-b.

f) Packet Call Setup Failure due to OtherAll other failures i.e. NOT AC, BTS, DMCU, TRANS or UE are counted as OTHER failures. If there are lots of failures due to other reasons then report to tier2 for further investigation.



3. Configuration ManagementConfiguration Management tools and methods should also be used in improving accessibility. Some of these items have been discussed already but these include:

– Neighbour List Optimization• Counts (3G-3G)

– Removals– Additions

– Antenna Changes• Tilts• Azimuths

xConfig should also be used to ensure all parameters are consistent with the FSC Baseline Set unless otherwise agreed for performance reasons.



4. Troubleshooting Tools

The following tools can be used for troubleshooting: Tektronix K-18

This is a protocol analyzer used for analysis of the Iu and Iub links and the layer 1, 2 and 3 messaging. This can be used for further analysis of the call flows

More detailed information on this can be found in the Tektronix Documentation

Optimizer The Optimizer is Nokia OSS Tool which provides suggestions

on missing neighbour additions and neighbour removals It also can provide geographical PRACH analysis for distance

from serving sector at call setup More detail on this tool can be found in NED



5. References1. 3GPP TS 25.331 V 5.19.0 “UMTS Radio Resource Control Protocol

Specification”.2. NED (Nokia Online)3. Alejandro Aguirre, Sireesha Panchagnula Ericsson UTRAN

Parameters.4. 3GPP TS 25.304 V 5.9.0 “UMTS UE Procedures in Idle Mode and

Procedures for Cell Reselection in Connected Mode”.5. UMTS Network KPI, U12 UMTS Network KPI v6.14 080406TMO LR.doc6. UMTS Network KPI Level 2, UMTS Network KPI Level-

2_v1_20070205ERI_Updated.doc7. UMTS RNC LCS KPI definitions and Formulas, Michael Gebretsadik8. 3GPP TS 25.331, UMTS RRC protocol specification.9. 3GPP TS 25.211 V 5.8.0, “UMTS Physical channels and mapping of

transport channels onto physical channels”.10. 3GPP TS 25.413 V 5.12.0, “UTRAN Iu Interface RANAP Signaling”.11. 3GPP TS 25.214, ”UMTS Physical Layer Procedures FDD”.


UMTS RAN Performance Trouble Shooting Guidelines – Nokia Accessibility Document Information

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