UMTS Performance Trouble Shooting and Optimization Guidelines Ericsson Accessibility

UMTS RAN Performance Trouble Shooting Guidelines – Ericsson UMTS Accessibility Performance Engineering

Introduction Purpose & Scope The intent of this document is to provide UMTS Trouble Shooting and Optimization from KPI and Counter perspectives for Ericsson (E///) 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 P6 release of Ericsson UTRAN. This document is not all inclusive and is only intended to provide a quick cook book to understand available E/// for trouble shooting and optimization best practices Guideline Document. For any information not covered here, Ericsson product documentation (CPI/ALEX Libraries) should be referenced.

Definitions for this Document Term or Acronym

Definition

3GPP

Third Generation Partnership Project

AS

Active Set

BSIC

Base Station Identity Code

BTS

Base Transceiver Station

CN

Core Network

CPICH

Common Pilot Channel

DCH

Dedicated Channel

DL

Downlink

DPCCH

Dedicated Physical Control Channel

DPCH

Dedicated Physical Channel

DRNC

Drift Radio Network Controller

FACH

Forward Access Channel

FIFO

First In First Out

GERAN

GSM EDGE RAN

Term or Acronym

Definition

GSM

Global System Communications

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

Node B Application Part Logical node responsible for radio transmission and reception in one or several cells

OCNS

Orthogonal Channel Noise Simulator

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 Radio Base Station – another name for the Node B

RBS

for

Mobile

Term or Acronym

Definition

RF

Radio Frequency

RL

Radio Link

RNC

Radio Network Controller

RRC

Radio Resource Control

RSCP

Received Signal Code Power

RSSI

Received Signal Strength Indicator

SIB

System Information Block

SIR

Signal to Interference Ratio

TRX

Transceiver

TX

Transmit

UE

User Equipment

UL

Uplink Universal Mobile Telecommunication Services

UMTS UTRAN WCDMA

UMTS Terrestrial Radio Access Network Wideband Code Division Multiple Access

Accessibility Accessibility is defined as the ability of a user to access the UMTS network successfully to utilize the available services. The metrics within Ericsson RNC and OSS provide counters and KPI’s that describe the behaviors and experience of the subscribers while accessing the UMTS network. This is divided up into a number of areas, CS and PS, as well as being divided on an RRC and RAB basis. The services which have counters for Accessibility are: •

CS Voice

•

CS Data

•

SRB

•

Video

•

PS Streaming & Interactive

•

HSDPA Streaming & Interactive

•

EUL (HSUPA)

In the following sections, CS Voice, PS Interactive and HSDPA will be discussed in detail.

Troubleshooting Flowchart The following flowchart may be useful for troubleshooting accessibility issues based on the problem areas

Flow chart in PowerPoint

Microsoft Office PowerPoint 97-2003 Presentation

Voice Access Failure Rate The metrics measures user ability to access the mobile network for circuit switched voice calls. The metrics consists of two components of CS Access call, RRC and RAB. RRC part of the equation measures Conversational (originating and terminating) and Emergency calls. The RAB part of the equation measures Speech RAB and is pegged on the best cell in the active set in Serving RNC. The RRC measures Conversational Voice and Data (CSV+CSD) while RAB part measures only Speech for both originating and terminating causes. The non-access stratum (signaling) part of the access call flow is not included in this KPI. KPI’s Formula & stats availability: KPI’s are based on following formulae. Voice Access Failures = Voice RRC Failures + Voice RAB failures

Voice Access Failure Rate (%) = 100 *

(1

– (Voice RRC Failure Rate* Voice RAB

Failure Rate))

Voice Access failures Breakdown These metrics can be used to determine the breakdown of access failures on an RNC, Market or Region level and can be shown as following to identify the distribution of RRC / RAB failures to total Voice access failures.

This chart helps us to analyze issues impacting Voice accessibility showing the breakdown between RRC & RAB failures and accordingly troubleshoot the prominent failures with help of corresponding counters listed for RRC & RAB failures.

CS Voice RRC Accessibility The counters for CS Voice RRC Accessibility are extensively available for the UMTS Services in Ericsson OSS; however RRC access failures formula is based on two counters. These metrics can be run on Cell /RNC/Market/Region level. This is made up of the following counters: Counter

Description

Condition

MO Class

pmTotNoRrcConnectReqCs

Total number of Conversation al Call (originating and terminating) and Emergency Call RRC Connection attempts Total number of Successful Conversation al Call (originating and terminating) and Emergency Call RRC Connection attempt

The counter is increased when the RRC Connection Request message is received with Establishment Cause ’Originating Conversational Call’ or ’Terminating Conversational Call’. Note: This counter does not count repeated RRC connection requests.

UtranCell

The counter is increased when an RRC Connection Setup Complete message is received following an attempt to setup an originating or terminating conversational call.

UtranCell

(CS RRC connection requests)

pmTotNoRrcConnectReqCsS ucc (CS RRC

connection successes)

This KPI shows the percentage of RRC access failures by the total number of RRC attempts. Following formula is used for these KPI:

To understand clearly the causes for CS RRC access failures, we would divide it in two main categories: a) CS RRC Setup Failures: These failures are mainly associated with RRC rejections due to MP load, Node-B / Transport network congestion or configuration errors, Cell Congestion (Admission Control) and insufficient licensed capacity. b) CS RRC Access (Radio reasons) Failures: These failures are mainly due to radio reasons. By subtracting RRC setup failures from Total RRC access failures, we can get the numbers for RRC access failures due to radio reasons. In Ericsson RNC, counters are available to breakdown RRC Setup failures to aid troubleshooting of such access issues. These single counter based KPIs are available in the same Accessibility report.

CS RRC Setup Failures Counters: (Pegged for CS calls only) Counter

Description

Condition

MO Class

pmNoRrcConnReqBlockTnCs

# RRC Connection Setup attempts for Circuit Switched calls that fail due to Transport Network blocking.

This counters is stepped if the establishment of an RRC Connection Request with Establishment Cause = Originating/Terminating Conversational or Emergency, fails due to congestion on the user plane (AAL2) or control plane (UniSaal or SCTP) of the transport network as a result of user dimensioned transport network resource shortages. This counter is stepped if the establishment of an RRC Connection Request - with Establishment Cause equal to Originating/Terminating Conversational or Emergency - fails due to node configuration error, node limitations or transport network layer service unavailability. Counter is triggered when an RRC CONNECTION REQUEST with the cause; “Originating Conversational Call”, “Terminating Conversational Call”, or “Emergency call” is denied by Admission Control. Incremented by one when an RRC connection request with cause Originating Conversational Call, Terminating Conversational call, or emergency call is denied by admission control due to insufficient licensed capacity in the

UtranC ell

(CS RRC fails - TN Congestion/Blocking)

pmNoRrcConnReqBlockNode Cs (CS RRC Fails -

NodeB Blocking)

pmNoRrcCsReqDeniedAdm

(CS RRC rejects due to Admission control)

pmNoFailedRrcConnectReqC sHw (CS RRC denied -

Insufficient Licensed Capacity)

# RRC Connection Setup attempts for Circuit Switched calls that fail due to node blocking. # CS calls denied by admission control. # CS calls denied by admission control due to insufficient licensed capacity in

UtranC ell

UtranC ell

UtranC ell

Counter

Description

Condition

the RBS.

RBS.

MO Class

RRC Setup Failures Counters: (Pegged for CS & PS calls together) Counter

Description

Condition

MO Class

pmNoRejRrcConnMpLoadC

# of rejected RRC connections due to module MP load control (includes incoming Inter-RAT CC)

Sending of the RRC message RRC connection Reject with rejection cause congestion when the congestion cause has been indicated by internal load control.

UtranC ell

(RRC reject due to MP load control)

Please Note This counter is pegged for CS & PS services.

Above mentioned counters can be used to determine the access failures caused by Setup issues in the cell. These counters can also be used in conjunction with the Total RRC failures for the trend analysis on the RNC/Market or Region level. Subtracting their value from total RRC failures can give us the Voice RRC access failures due to radio reasons – Radio Reasons CS RRC access failures = (Total CS RRC access failures)–(CS RRC Setup failures) A special attention must be paid for using (RRC reject due to MP load control) counter as this is pegged for both CS & PS calls, so contribution from CS & PS RRC access failures to this counter value must be decided based on CS & PS total RRC failures.

There are two additional counters available also which are pegged for both CS + PS calls and Setup + Radio access failures together. So, these counters can be used more for information & trending instead of troubleshooting.

RRC Failures Counters: (Pegged for CS + PS calls and Setup + Radio Access failures together) Counter

Description

Condition

MO Class

pmTotNoUtranRejRrcConnRe q (Total RRC rejects by

Total number of UTRAN rejected RRC Connection

When an RRC Connection Request is received and no internal UE identity is available in the RNC, or MP load

UtranC ell

UTRAN)

Counter

pmNoFailedAfterAdm

(RRC+RAB) Failures after Admission Control

Description

Condition

Requests

control function, or Admission Control function does not grant permission to proceed, or any internal parameter retrieving or calculations fail, or a DL channelization code fails to be allocated, A connection fails to be setup to the RBS, this counter is increased. Note: This counter is never stepped if there is inter-frequency loadsharing. The counter is increased if a function that has been granted admission for a UE fails after being admitted due to a problem in the RRC or RAB Setup procedure. Then the admission control function must be informed about the release of previously requested resources due to the failed procedure and this counter is increased. The counter is

# RRC or RAB establishmen t requests failed after being admitted by admission control.

(Please note this counter also counts RAB failures)

MO Class

UtranC ell

increased in the cell or cells where the UE is located. This counter is stepped for all cells if UE is in macrodiversity. Note: The counter is not stepped for D-RNC cells or at failure of repeated RRC connection requests.

RNC/Market/Region Level Reporting This section covers analysis of Accessibility % for Ericsson and identification of issues using the available Ericsson accessibility counters.

CS RRC Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level and can be shown as following.

VoiceRRCFailuresDistribution CSRRC Failures_Radio Access

100%

CSRRC Failures_Setup

90% 80% 70% 60% 50% 40% 30% 20% 10%

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0%

Figure : CS RRC’s accessibility mostly influenced by Radio Access Failures, however on certain days, RRC setup failures have also increased significantly to 60%, for example on 1/1/2009) In the next chart, we would break up the causes for these setup failures to identify the prominent cause for such failures:

Figure : “RRC rejects due to MP Load” is the main cause for CS RRC setup failures increasing as high as 100% on certain days.

Although this chart provides an overview of Setup issues impacting CS RRC accessibility, yet the highlighting point of this chart is CS RRC failures due to NodeB Blocking (failures due to node configuration error, node limitations or transport network layer service unavailability) which increased up to 95+% on 1/31/2009. This is where optimizers must focus their attention also to ensure NodeB’s configuration is appropriate to meet traffic demand.

Since the counter for “RRC rejects due to MP Load” is stepped up for all network access causes (CS call, PS call, SMS, Location update), hence appropriate estimation should be made during analysis to count CS RRC failures due to this reason. This has been done in to plot the values for RRC reject due to Mp load (CS calls) in graphs for figure 3 & 4. Following methodology was used i)

Ratio (%) for CS RRC attempts to total RRC attempts was calculated.

ii)

Same ratio was then applied to “RRC rejects due to MP Load” counter value to calculate the value for RRC reject due to Mp load (CS calls) used in this graph.

Plotting the same causes in Bar format graph to show number of failures per reason.

Figure “RRC rejects due to MP Load” is the main cause for RRC setup failures increasing as high as 100% on certain days.

Cell Analysis CS RRC Setup Phase Failure Causes a) CS RRC rejects due to Admission control This counter is pegged when the RNC decides to reject the RRC connection request because of the Admission control on the cell. This admission control can be initiated generally due to lack of downlink power or lack of downlink channelization codes as seen in the Northeast network until now since commercial launch. Problem can be due to uplink causes also but downlink ideally gets congested before uplink. However, before concluding this admission control has been triggered due to increased traffic in the cell, please verify following 3 main points: i)

OCNS is deactivated on the cell.

ii)

Feeder length attenuation & TMA parameters are set correctly as per CIQ.

iii)

Admission control parameters (Power Adm, power offset, dlcodeAdm…) are consistent to Baseline values.

b) CS RRC Fails - NodeB Blocking This counter is stepped up fails due to node configuration error, node limitations or transport network layer service unavailability. So, please check Transport network availability (T1 related issues which can be checked from T1 error counters) to identify the main cause for these failures. c) CS RRC Fails – Transport Network Blocking This counter is stepped up fails due to congestion on the user plane (AAL2) or control plane (UniSaal or SCTP) of the transport network as a result of user dimensioned transport network resource shortages. So, please verify IuB link AAl2 path (ATM cells) configuration to identify the main cause for these failures. d) CS RRC denied - Insufficient Licensed Capacity This counter value is stepped due to potential hardware, configuration or resource issue in the Node-B. Resource congestions can be verified from the Channel Element usage counters. If traffic is low and CE usage is high, it may be due to hanging resources. However, If traffic is high, it might be due to shortage of license keys for CE. (Compare the max CE used counters with installed license keys in the Node-B). Also check the number of users in Compressed Mode. Current parameter settings allow maximum 16 users in Compressed Mode. 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 not clear or repeats a ticket should be open with the field technicians to investigate. Potential issues on the site that can cause this problem can 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 be used to reload the software in the site) • Faulty hardware (System module).

e) RRC rejects due to High MP Load This counter value is generally stepped whenever the issue is RNC wide or multiple sites connected to Main / Extension sub-Rack of RNC. It is unlikely that this will step up for a cell specific issue. So, please check for Core network (MSS/SGSN) outages if this counter value is exceptionally high on any given day. MP load counters are available from Capacity 1 report to correlate these rejections with high load. For the regularly reported values of this counter, please check sites configuration on Main & Extension sub-racks of the RNC. As this may require, rehoming of sites from one rack to another or addition of new Extension Sub-rack to decrease MP load on all sub-racks.

0.0.0.1. CS RRC Radio Access Phase Failure Causes a) CS RRC Connections Access Failure due to Radio Reasons These 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 WMRR/drive test analysis. Also verify that the uplink RTWP value for these sites is within acceptable range to isolate the problem due to uplink issues. b) CS RRC Connections Access Failure due to UE Failures The cause for this counter can be coverage even though L1 synchronization has been achieved it can still be that a sudden loss in 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 RTWP value for these sites is within acceptable range to isolate the problem due to uplink issues. c) CS RRC Connections Access Failure due to RNC Failures If the counter is showing a step change it might be related to a new software load that was loaded on the RNC or core network side. To trouble shoot these problem it will require in-depth analysis on the RNC 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)

Worst Cells Analysis All of the mentioned metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level should be ranked by the following metrics: •

CS RRC access failures

•

CS Radio Reasons RRC access failures

•

CS RRC access failures due to Admission control

•

CS RRC access fails –Node B/ TN Congestion

CS Voice RAB Accessibility The metrics for CS Voice RAB Accessibility are extensively available also and similar to RRC accessibility, CS .KPIs are based on following two counters: Counter

Description

Condition

MO Class

pmNoRabEstablishAttemptS peech (CS Voice RAB

Number of RAB establishmen ts attempts (Speech) referred to the Best Cell in the Active Set.

The counter is incremented after successful RAB Mapping when when a RANAP RAB Assignment Request message is received from the CN with RABs to be setup or modified. The counters shall be reported per single RAB state on Best Cell level for each RAB that is established Note: This counter is only incremented in the SRNC. This counter is incremented after successful RAB Establishment (on DCH or common channel) before sending the RANAP RAB

UtranCell

connection requests)

pmNoRabEstablishSuccessS peech (CS Voice RAB

connection success)

Number of successful RAB establishmen ts (Speech)

UtranCell

referred to the Best Cell in the Active Set.

Assignment Response message to the CN.

Formula: Following formulas are used for these KPIs:

Similar to CS RRC access failures breakdown, CS RAB access failures are also broken down in two main categories: c) CS RAB Setup Failures: These failures are mainly associated with RRC rejections due to MP load, Node-B / Transport network congestion or configuration errors, Cell Congestion (Admission Control), Lack of hardware resources, lack of ASE and UE capability. d) CS RAB Access (Radio reasons) Failures: These failures are mainly due to radio reasons. By subtracting RRC setup failures from Total RRC access failures, we can get the numbers for RRC access failures due to radio reasons.

CS RAB Setup Failures Counters: (Pegged for CS calls only) Counter

Description

Condition

MO Class

pmNoOfNonHoReqDeniedSp eech (Voice

Number of Speech RAB establishments rejected by admission control. Note: The counter is applicable to all Speech RAB establishments including establishment on a Speech /Interactive multi RAB configuration. Number of RAB establishment attempts for RAB-type Speech that are blocked due to TN congestion or TN failure, counted on the best cell.

The counter is increased in the cell where admission is rejected. Note: The counter is not stepped when admission is rejected in a D-RNC cell.

UtranCell

This counter is stepped when the establishment of a Speech RAB fails due to UNI-SAAL or AAl2 congestion, IP resource limitations or blocking as a result of

UtranCell

RAB Failures due to Admission Control)

pmNoRabEstBlockTnSpeech Best (Speech

RAB Block - TN Congestion/Failure (Best Cell)

Counter

pmNoRabEstBlockTnSpeech

(Speech RAB Block - TN Congestion/Failure (Blocked cell)

pmNoRabEstBlockNodeSpee chBest (Speech RAB

Block - Node Congestion/Failure (Best Cell)

Description

Number of RAB establishment attempts for RAB-type Speech that are blocked due to TN congestion or TN failure, counted on the blocking cell.

Number of RAB establishment attempts for RAB-type CS Speech that are blocked due to node congestion or node failure, counted on the best cell.

Condition user dimensioned transport network configured capacity. The counter is stepped for the best cell in the active set but only if the cell is in the SRNC. This counter is stepped when the establishment of a Speech RAB fails due to congestion on the user plane (AAL2) or control plane (UniSaal or SCTP) of the transport network as a result of user dimensioned transport network resource shortages. This counter is stepped when the establishment of a CS Speech RAB fails due to node configuration error, node limitation, or transport network layer service unavailability.

MO Class

UtranCell

UtranCell

CS RAB Setup Failures Counters: (Pegged for CS & PS calls) Counter

Description

Condition

MO Class

PmNoFailedRabEstAttemptLackDlPwr

Number of failed RAB establishment attempts due to lack of DL power

Counter is stepped when admission control fails with reject reason lack of DL power. Number of failed RAB establishment attempts due to lack of DL channelization codes.

UtranCel l

(RAB failures - Lack of DL power) pmNoFailedRabEstAttemptLackDlCh nlCode (RAB failures -

Lack of DL Channelization code)

Number of failed RAB establishment attempts due to lack of DL channelization codes.

UtranCel l

Counter

Description

Condition

MO Class

PmNoFailedRabEstAttemptLackDlAse

Number of failed RAB establishment attempts due to lack of DL ASE

Counter is stepped when admission control fails with reject reason lack of DL ASE. Number of failed RAB establishment attempts due to lack of UL ASE. The counter is stepped for the IubLink containing the best cell in the active set.

UtranCel l

The counter is stepped for the IubLink containing the best cell in the active set.

UtranCel l

The counter is stepped for the IubLink containing the first cell to fail admission in the active set When the Ue Capability check fails for the state to which it is established, the counter is incremented.

UtranCel l

(RAB failures - Lack of DL ASE) pmNoFailedRabEstAttemptLackUlAse

(RAB failures - Lack of UL ASE)

pmNoFailedRabEstAttemptLackUlHw Best (RAB failures - Lack of UL

hardware resources- Best cell)

pmNoFailedRabEstAttemptLackDlHw Best (RAB failures - Lack of

DL hardware resources- Best cell)

pmNoFailedRabEstAttemptLackUlHw (RAB failures - Lack of UL

hardware resources)

pmNoRabEstablishFailureUeCapabilit y (RAB failures due to UE

Capability)

Number of failed RAB establishment attempts due to lack of UL ASE Number of failed RAB establishment attempts due to lack of UL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of DL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of UL hardware resources. Number of failed RAB establishments due to insufficient UE capabilities

UtranCel l UtranCel l

UtranCel l

Above mentioned counters can be used to determine the access failures caused by Setup issues in the cell. These counters can also be used in conjunction with the Total CS RAB failures for the trend analysis on the RNC/Market or Region level. Subtracting their value from total RRC failures can give us the CS RAB access failures due to radio reasons – Radio Reasons CS RAB access failures = (Total CS RAB access failures)–(CS RAB Setup failures)

A special attention must be paid for using counters pegged for both CS & PS calls. Contribution from CS & PS RAB access failures to this counter value must be decided based on ratio of CS & PS total RAB failures. There 1 more counter available also which are pegged for both CS + PS calls and Setup + Radio access failures together. So, this counter can be used more for information & trending instead of troubleshooting. (already mentioned in CS RRC access failure part of this report)

RAB Failures Counter: (Pegged for CS + PS calls and Setup + Radio Access failures together) Counter

Description

Condition

MO Class

pmNoFailedAfterAdm

# RRC or RAB establishmen t requests failed after being admitted by admission control.

The counter is increased if a function that has been granted admission for a UE fails after being admitted due to a problem in the RRC or RAB Setup procedure. Then the admission control function must be informed about the release of previously requested resources due to the failed procedure and this counter is increased. The

UtranC ell

(RRC+RAB) Failures after Admission Control

(Please note this counter also counts RAB failures)

counter is increased in the cell or cells where the UE is located. This counter is stepped for all cells if UE is in macrodiversity. Note: The counter is not stepped for D-RNC cells or at failure of repeated RRC connection requests.

CS RAB Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level and can be shown as following.

VoiceRABAccessFailures 100%

VoiceRABRadio AccessFailures

Voice RABSetup Failures

90% 80% 70% 60% 50% 40% 30% 20% 10%

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0%

Figure : New Jersey RAB’s accessibility mostly influenced by Radio Access Failures. Everyday ~90% of the failures are reported due to Radio Reasons. In the next chart, we would break up the causes for these setup failures to identify the prominent cause for such setup failures:

VoiceRABSetupFailuresDistribution CSRABBlock -Node Congestion/Failure(Best Cell)

CSRABFailures_AdmControl

CSRABBlock -TN Congestion/Failure(Blocked cell)

CSRABBlock -TN Congestion/Failure(Best Cell)

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Figure 6: “CS RAB failures due to – Node Congestion” is the main cause for CS RAB setup failures. Although Figure 6 chart provides an overview of setup issues impacting CS RAB accessibility, yet the highlighting point of this chart is CS RAB failures due to Admission Control which has increased from 2/1/2009 . This site has high traffic but

verifying the parameter settings before concluding these rejects are caused due to increased traffic. Plotting the same causes in Bar format graph to show number of failures per reason.

VoiceRABSetupFailuresDistribution CSRABBlock -Node Congestion/Failure(Best Cell)

CSRABFailures_AdmControl

CSRABBlock -TN Congestion/Failure(Blocked cell)

CSRABBlock -TN Congestion/Failure(Best Cell)

1,400 1,200 1,000 800 600 400 200

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0

Figure : “CS RAB failures due to – Node Congestion” is the main cause for CS RAB setup failures. Following flowchart also explains how Capacity management system works in E/// OSS system.

This flowchart helps us to understand Downlink/Uplink power, channelization codes, ASE, Hardware resources and UTRAN parameters are the key aspects we must look at before concluding congestion in the cell is due to increased traffic.

The following set of system resources are relevant within the Capacity Management scope:

Per Cell:          

Downlink channelization codes Downlink transmitted carrier power, non-HS part and HS-required part Air Interface Speech Equivalents (ASE) in uplink and downlink Uplink Received Total Wideband Power (RTWP) The number of radio links per DL Spreading Factor (not including the codes (spreading factor = 16) reserved for or used by HSDPA connections) The number of radio links per UL Spreading Factor (not including codes used by EUL) The number of radio links in compressed mode The number of serving HS connections The number of serving EUL connections The number of non-serving EUL connections

Per Hardware Pool: 

RBS hardware utilization in uplink (both DCH and EUL) and downlink (both DCH and MTCH)

To monitor the system resources, Capacity Management performs periodic and event based measurements and keeps track of every radio connection setup, deletion and modification in a cell.

Since the counter for RAB failures due to lack of Tx Power/channelization codes/ASE/Hardware resources are stepped up for CS & PS calls, hence appropriate estimation should be made during analysis to count CS RAB failures due to this reason. In the next chart, counters for Downlink path has been shown for clear visibility in the graph as RAB setup failures due to admission control are only in downlink & not in uplink.

RABSetupFailuresDistribution RABfailures

- Lackof DLpower

RABfailures

- Lackof DLChannelization code

RABfailures

- Lackof DLASE

RABfailures

- Lackof DLhardwareresources

3,000 2,500 2,000 1,500 1,000 500

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0

Figure : “CS RAB setup failures due to lack of Downlink Tx power” is the main cause for CS RAB setup failures. Although this chart highlights lack Downlink Tx Power is the prominent cause triggering admission control in this market, however attention must be paid to RAB setup failures due to lack of channelization code. In the next section, root causes for such failures have been explained.

CS RAB Setup Failure Causes a) CS RAB Setup Failure Due to Admission Control Same as CS RRC admission control b) CS RAB Failures - NodeB Blocking (Best Cell) Same as CS RRC NodeB Blocking c)

CS RRC Fails – Transport Network Blocking(Best cell) / (Blocked cell)

Same as CS RRC Transport Network Blocking d) CS RAB Setup Failure Due to lack of DL/UL Tx power Same as CS RRC admission control e) CS RAB Failures Due to lack of DL Channelization Codes Same as CS RRC admission control . However, along with checking Admission control parameters & OCNS activation status, channelization code (code tree) utilization trend must be checked to confirm the lack of resources.

f) CS RAB Failures Due to lack of DL / UL ASE Uplink / Downlink ASE admission policy provides a way to limit excessive interference in the respective direction (UL / DL) avoiding large variations in cell breathing. Hence, whenever RAB failures are reported due to lack of ASE, high interference should be observed in that cell for the respective link asking for UMTS radio network optimization. However, current baseline settings has disabled DL & UL ASE admission policy, hence counters for CS RAB Failures Due to lack of DL/UL should not be

pegged. g) CS RAB Setup Failure Due to lack of DL/ UL Hardware Resources Whenever the hardware utilization in uplink and downlink by means of Channel Elements (CE) usage for dedicated channels is higher than utilization thresholds (separate for UL and DL), this counter is stepped up indicating towards the need of additional hardware in RBS to support traffic demand. Thresholds for CE usage are related to the HW cost-model of the RBS. There may be different cost models for different channels types and for different RBSs (depending on HW type used), and therefore the HW cost-model in uplink may differ. h) CS RAB Setup Failure Due to UE Capability RAB Failure due to Non-supported Request. RAB setup attempt is not started due to requested parameters are not supported by the RNC. (e.g. 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.

Voice RAB Radio Access Failure Causes a) Voice RAB Access Failure Due to Radio Reasons Same as CS RRC access failures due to MS b) Voice RAB Access Failure Due to UE failures Same as CS RRC access failures due to MS

c) Voice RAB Access Failure Due to RNC Internal Failures Same as CS RRC setup failures due to RNC

Worst Cells Analysis All of the mentioned metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level should be ranked by the following metrics: •

Voice RAB access failures

•

Voice RAB access failures – Radio Reasons

•

Voice RAB access failures – Admission Control

•

Voice RAB access failures –Node B/ TN Congestion

Packet Interactive Access Failure Rate This metrics measures user ability to access the mobile network for PS (interactive) including HSDPA. The metrics consists of two components of PS Access call, RRC and RAB. The RRC part of the equation measures PS (Interactive) for both originating and terminating calls. For multiple RRC connection request only one is considered corresponding to one call. The RAB part of the equation measures PS interactive (R99 and HS) RAB and is pegged on the best cell in the active set in Serving RNC. The nonaccess stratum (signaling) and PDP access part of the access call flow for Streaming is not included in this KPI. After RRC setup, PS interactive RAB type depends on service requested by the UE, resources availability and features enabled in UTRAN network, e.g. R99 interactive RAB, HSDPA interactive, R99 streaming, HSDPA streaming, EUL (HSUPA) etc. Since R99 streaming, HSDPA streaming, EUL features are not currently activated in the network, hence we are only covering R99 interactive RAB & HSDPA interactive RAB accessibility in this document. For easier understanding and clarity, R99 interactive access failure section has been separated from the HSDPA interactive access failure’s section in this report. Hence, PS Interactive Access failures are now classified in 3 sub sections for detailed discussion. a) Packet Interactive RRC Access Failure Rate (common for both R99 & HSDPA) b) R99 Interactive RAB Access Failure Rate c) HSDPA Interactive RAB Access Failure Rate KPI’s Formula & stats availability: 2 KPI’s are available in T-PIM accessibility detailed report and these KPI’s are based on following formulae. PS Interactive Access Failures = PS Int RRC Failures + PS Int RAB failures

PS Interactive Access Failures (%) = 100 * (1 – (PS Int RRC Failure Rate* PS Int RAB Failure Rate))

PS Interactive Access failures Breakdown These metrics can be used to determine the breakdown of access failures on an RNC, Market or Region level and can be shown as following.

Figure : “PS RRC Access Failures” are the main cause for PS Access failures. This chart helps us to analyze issues impacting Packet Interactive accessibility showing the breakdown between RRC & RAB failures and accordingly troubleshoot the prominent failures with help of corresponding counters listed these failures. Contrary to Voice Access failures trend, PS RRC failure rate is higher PS RAB failure rate.

Cell/RBS Analysis PS access failure metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level could be ranked by the following metrics: •

PS Interactive access failures

•

PS Interactive RRC access failures

•

PS Interactive RAB access failures

Now in the next 3 sub sections, we would discuss in detail the following 3 main KPIs. a) Packet Interactive RRC Access Failure Rate (common for both R99 & HSDPA) b) R99 Interactive RAB Access Failure Rate c) HSDPA Interactive RAB Access Failure Rate

PS Interactive RRC Accessibility The KPI for PS Int RRC access failures is the PS Interactive RRC Access Failure Rate%. This KPI is cumulative for R99 Interactive + HSDPA interactive. Following counters are directly making up these PS interactive RRC access failures: Counter

Description

Condition

MO Class

pmTotNoRrcConnectReqPs

Total number of 'Originating Interactive Call', 'Terminating Interactive Call', 'Originating Background Call', 'Terminating Background Call' or 'Originating Subscribed Traffic Call', RRC connection attempts.

UtranCell

pmTotNoRrcConnectReqPsS ucc (PS RRC

Total number of Successful 'Originating Interactive Call', 'Terminating Interactive Call', 'Originating Background Call', 'Terminating Background Call', or 'Originating Subscribed Traffic Call' RRC connection setups.

Counter is increased when the RRC Connection Request message is received with Establishment Cause 'Originating Interactive Call', 'Terminating Interactive Call', 'Originating Background Call', 'Terminating Background Call', or 'Originating Subscribed Traffic Call'. The counter is increased when an RRC Connection Setup Complete message is received following an attempt to setup Originating Interactive Call', 'Terminating Interactive Call', 'Originating Background Call', 'Terminating Background Call' or 'Originating Subscribed Traffic Call'.

(PS RRC connection requests)

connection successes)

UtranCell

Above mentioned counters can be used in the following formulae to calculate PS RRC access failures & Failure rate (%):

To understand clearly the causes for PS RRC access failures, we would divide it in two main categories:

a) PS RRC Setup Failures: These failures are mainly associated with RRC rejections due to MP load, Node-B / Transport network congestion or configuration errors, Cell Congestion (Admission Control) and insufficient licensed capacity.

b) PS RRC Access (Radio reasons) Failures: These failures are mainly due to radio reasons. By subtracting RRC setup failures from Total RRC access failures, we can get the numbers for RRC access failures due to radio reasons.

PS RRC Setup Failures Counters: (Pegged for PS calls only) Counter

Description

Condition

MO Class

pmNoRrcConnReqBlockTnPs

Number of RRC Connection Setup attempts for Packet Switched calls that fail due to Transport Network blocking.

UtranCell

pmNoRrcConnReqBlockNode Ps (PS RRC Fails -

Number of RRC Connection Setup attempts for Packet Switched calls that fail due to node blocking.

This counters is stepped if the establishment of an RRC Connection Request with Establishment Cause = Originating/Terminating Interactive or Background or Originating Subscribed Traffic Call, fails due to congestion on the user plane (AAL2)or control plane (UniSaal or SCTP) of the transport network as a result of user dimensioned transport network resource shortages. This counter is stepped if the establishment of an RRC Connection Request - with Establishment Cause equal to Originating/Terminating Interactive, or Background or Originating Subscribed Traffic Call - fails due to node configuration error, node limitations or transport network layer service unavailability. Counter is stepped after denied admission after an RRC CONNECTION REQUEST with any of the cause values 'Originating Interactive Call', 'Terminating Interactive Call', 'Originating Background Call', 'Originating Subscribed Traffic Call' or 'Terminating Background Call' has been received. Incremented by one when an RRC connection request with cause Originating Conversational Call, Terminating Conversational call, or emergency call is denied by admission control

(PS RRC fails - TN Congestion/Blocking)

NodeB Blocking)

pmNoRrcPsReqDeniedAdm

Number of PS calls denied by admission control.

pmNoFailedRrcConnectReqP sHw (PS RRC denied -

Number of PS calls denied by admission control due to insufficient licensed capacity in the RBS.

(PS RRC rejects due to Admission control)

Insufficient Licensed Capacity)

UtranCell

UtranCell

UtranCell

RRC Setup Failures Counters: (Pegged for CS & PS calls together) Counter

Description

Condition

MO Class

pmNoRejRrcConnMpLoadC

# of rejected RRC connections due to module MP load control (includes incoming InterRAT CC)

Sending of the RRC message RRC Connection Reject with rejection cause congestion when the congestion cause has been indicated by internal load control. Please Note

UtranC ell

(RRC reject due to MP load control)

This counter is pegged for CS & PS services.

Above mentioned counters can be used to determine the PS RRC access failures caused by Setup issues in the cell. These counters can also be used in conjunction with the Total RRC failures for the trend analysis on the RNC/Market or Region level. Subtracting their value from total RRC failures can give us the PS RRC access failures due to radio reasons – Radio Reasons PS RRC access failures = (Total PS RRC access failures)–(PS RRC Setup failures) A special attention must be paid for using (RRC reject due to MP load control) counter as this is pegged for both CS & PS calls, so contribution from CS & PS RRC access failures to this counter value must be decided based on CS & PS total RRC failures.

There are two additional counters available also which are pegged for both CS + PS calls and Setup + Radio access failures together. So, these counters can be used more for information & trending instead of troubleshooting.

RRC Failures Counters: (Pegged for CS + PS calls and Setup + Radio Access failures together) Counter

Description

Condition

MO Class

pmTotNoUtranRejRrcConnRe q (Total RRC rejects by

Total number of UTRAN rejected RRC Connection Requests

When an RRC Connection Request is received and no internal UE identity is available in the RNC, or MP load control function, or Admission Control function does not grant permission to proceed, or any internal parameter retrieving or calculations fail, or a DL channelization code fails to be allocated,

UtranC ell

UTRAN)

Counter

pmNoFailedAfterAdm

(RRC+RAB) Failures after Admission Control

Description

Condition

# RRC or RAB establishmen t requests failed after being admitted by admission control.

a connection fails to be setup to the RBS, this counter is increased. Note: This counter is never stepped if there is inter-frequency loadsharing. The counter is increased if a function that has been granted admission for a UE fails after being admitted due to a problem in the RRC or RAB Setup procedure. Then the admission control function must be informed about the release of previously requested resources due to the failed procedure and this counter is increased. The

(Please note this counter also counts RAB failures)

MO Class

UtranC ell

counter is increased in the cell or cells where the UE is located. This counter is stepped for all cells if UE is in macrodiversity. Note: The counter is not stepped for D-RNC cells or at failure of repeated RRC connection requests.

PS RRC Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level and can be shown as following.

Figure : PS RRC’s accessibility mostly influenced by Radio Access Failures, however on certain days, RRC setup failures have also increased significantly to 60%, for example on 1/1/2009) In the next chart, we would break up the causes for these setup failures to identify the prominent cause for such failures:

Figure : “RRC rejects due to MP Load” is the main cause for PS RRC setup failures increasing as high as 99% on certain days,

Although this chart provides an overview of Setup issues impacting CS RRC accessibility, yet the highlighting point of this chart is CS RRC failures due to - NodeB Blocking (failures due to node configuration error, node limitations or transport network layer service unavailability) which increased up to 100+% on 1/31/2009. This is where optimizers must focus their attention also to ensure Node-B’s configuration is appropriate to meet traffic demand.

Since the counter for “RRC rejects due to MP Load” is stepped up for all network access causes (CS call, PS call, SMS, Location update), hence appropriate estimation should be made during analysis to count PS RRC failures due to this reason. This has been done in to plot the values for RRC reject due to Mp load (PS calls) in graphs for figure 3 & 4. Following methodology was used iii)

Ratio (%) for PS RRC attempts to total RRC attempts was calculated.

iv)

Same ratio was then applied to “RRC rejects due to MP Load” counter value to calculate the value for RRC reject due to Mp load (PS calls) used in this graph.

Plotting the same causes in Bar format graph to show number of failures per reason.

PSRRCSetupFailuresDistribution RRC reject due to MP load control (PS Calls)

PSRRC rejectsdue to Admission control

PSRRC denied - Insufficient Licensed Capacity

PSRRC fails - TN Congestion/Blocking

PSRRC Fails - NodeB Blocking 3,000,000 2,500,000 2,000,000 1,500,000 1,000,000 500,000

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0

Figure : “RRC rejects due to MP Load” is the main cause for RRC setup failures increasing as high as 99% on certain days; e.g. 1/31/2009

Cell Analysis PS RRC Setup Phase Failure Causes a) PS RRC Setup Failure Due to Admission Control Same as CS RRC admission control

b) PS RAB Failures - NodeB Blocking (Best Cell) Same as CS RRC NodeB Blocking d) PS RRC Fails – Transport Network Blocking(Best cell) / (Blocked

cell) Same as CS RRC Transport Network Blocking d) PS RRC denied - Insufficient Licensed Capacity Same as CS RRC Transport Network Blocking

e) PS RRC rejects due to High MP Load Same as CS RRC admission control f) PS RRC Setup Failures Due to lack of DL/UL Tx power Same as CS RRC admission control g) PS RRC Failures Due to lack of DL Channelization Codes Same as CS RRC admission control . However, along with checking Admission control parameters & OCNS activation status, channelization code (code tree) utilization trend must be checked to confirm the lack of resources.

PS RRC Radio Access Failure Causes a) PS RRC Connections Access Failure due to Radio Reasons Same as CS RRC access failures due to Radio Reasons

b) PS RRC Access Failure Due to UE Failures Same as CS RRC access failures due to MS

c) PS RRC Access Failure Due to RNC Internal Failures Same as CS RRC setup failures due to RNC

Worst Cells Analysis All of the mentioned metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level should be ranked by the following metrics: •

PS RRC access failures

•

PS Radio Reasons RRC access failures

•

PS RRC access failures due to admission control

•

PS RRC access fails –Node B/ TN Congestion

R99 Interactive RAB Accessibility In Ericsson OSS, same metrics for R99 interactive RAB Accessibility are available as for CS RAB accessibility. R99 interactive RAB accessibility is also based on two counters which are pegged on the best cell in the active set in Serving RNC. These metrics can be run on Cell/RNC/Market/Region level. The counters are as follows: Counter

Description

Condition

MO Class

pmNoRabEstAttemptPsIntN onHs (R99 Interactive

Number of RAB establishment attempts for the PS Interactive RAB in a nonHS configuration (that is on DCH or FACH). Reported on the best cell in the active set. Number of successful RAB establishment s for the PS Interactive RAB in a nonHS configuration (that is on DCH or FACH). Reported on the best cell in the active set.

Incremented by one when a RANAP RAB Assignment Request message is received from the CN with RABs to be set up or modified, after successful RAB mapping to PS Interactive. The counter is reported per single RAB state for each RAB that is attempted, on the best cell in the active set, only when the last reattempt is on a nonHS configuration (that is on DCH/DCH or RACH/FACH).

UtranCell

Incremented by one after sending the RANAP RAB Assignment Response message to the CN, indicating a successful PS Interactive RAB establishment. The counter is reported per single RAB state for each RAB that is established, on the best cell in the active set, only if the last reattempt is on a non-HS configuration (that is on DCH/DCH or RACH/FACH).

UtranCell

RAB connection requests)

PmNoRabEstSuccessPsIntN onHs (R99 Interactive

RAB connection successes)

Formula:

However, this formula is not implemented in XPM and we only get the values of PS R99 Interactive RAB access failures based on following formula and not the failure rate (%).

In Ericsson RNC, there are counters available that breakdown some of R99 interactive RAB Access failures to aid the troubleshooting of issues. All these single counter based KPI’s are available in T-PIM Accessibility detailed report.

R99 Interactive RAB Setup Failures Counters: (Pegged for PS calls only) Counter

Description

Condition

MO Class

pmNoOfNonHoReqDeniedSpe ech (PS

Number of Interactive RAB establishments rejected by admission control.

Incremented by one when admission is rejected.

UtranC ell

Interactive RAB Failures due to Admission Control)

pmNoRabEstBlkNodePsIntNo HsBest (R99 Int RAB

Block - Node Congestion/Failure (Best Cell)

pmNoRabEstBlockTnPsIntNon Hs (R99 Int RAB

Block - TN

Note: The counter is applicable to all Interactive RAB establishments including establishment on a Speech/Interactive multi RAB configuration. Number of RAB establishment attempts for RAB-type PS Interactive that are blocked due to node congestion or node failure, counted on the best cell. Number of RAB establishment attempts for RAB-type PS

Note: The counter is not incremented when admission is rejected in a DRNC cell.

This counter is stepped when the establishment of a PS Interactive RAB, excluding PS Interactive for HS, RAB fails due to node configuration error, node limitation or transport network layer service unavailability. This counter is stepped when the establishment of a PS Interactive RAB,

UtranC ell

UtranC ell

Counter

Description

Condition

Congestion/Failure (Blocking cell)

Interactive that are blocked due to TN congestion or TN failure, counted on the blocking cell.

pmNoRabEstBlockTnPsIntNo HsBest (R99 Int RAB

Number of RAB establishment attempts for RAB-type PS Interactive that are blocked due to TN congestion or TN failure, counted on the best cell.

not including PS Interactive for HS, fails due to congestion on the user plane (AAL2) or control plane (UniSaal or SCTP) of the transport network layer as a result of user dimensioned transport network capacity. Step counter when the establishment of a PS Interactive (excluding HS) RAB fails due to UNISAAL or AAl2 congestion, IP resource limitations or blocking as a result of user dimensioned transport network configured capacity.

Block - TN Congestion/Failure (Best Cell)

pmNoFailedREstAttExcConnLi mit (PS RAB failures -

Exceeded connection limit)

Number of failed PS RAB establishment attempts due to exceeding the configured connection limit when allocating Spreading Factor ('SF Histogram' in Admission Reject signal)

The counter is stepped for the best cell in the active set but only if the cell is in the SRNC. Counter is stepped when admission control fails with reject reason value SF8, SF16, or SF32.

MO Class

UtranC ell

UtranC ell

Since, there is no direct counter available for R99 Interactive RAB Failures due to Admission Control, so we can calculate it by using the following formula based on other 2 KPIs from this accessibility report (listed as # 1 & #2 in the table shown above).

R99 Int RAB Failures due to Admission Control = (PS Int RAB Failures due to Admission Control) – (HSDPA Int RAB Failures due to Admission Control)

To calculate the values for R99 RAB failures due to radio reasons, we can use the following formula

R99 RAB access failures (Radio Reasons) = (Total R99 RAB access failures) –(R99 RAB setup failures) Additional counters are also available to provide insight on R99 RAB accessibility failures but these are pegged for both CS & PS RABS, hence a fair estimation is required to correlate these reasons to R99 Interactive RAB access failures.

RAB Setup Failures Counters: (Pegged for CS & PS calls together) Counter

Description

Condition

MO Class

PmNoFailedRabEstAttemptLackDl Pwr (RAB failures -

Number of failed RAB establishment attempts due to lack of DL power

Counter is stepped when admission control fails with reject reason lack of DL power. Number of failed RAB establishment attempts due to lack of DL channelization codes. Counter is stepped when admission control fails with reject reason lack of DL ASE. Number of failed RAB establishment attempts due to lack of UL ASE. The counter is stepped for the IubLink containing the best cell in the active set.

UtranC ell

The counter is stepped for the IubLink containing the best cell in the active set.

UtranC ell

The counter is stepped for the IubLink containing the first cell to fail admission in the

UtranC ell

Lack of DL power) pmNoFailedRabEstAttemptLackDl ChnlCode

(RAB failures - Lack of DL Channelization code) PmNoFailedRabEstAttemptLackDl Ase (RAB failures -

Lack of DL ASE) pmNoFailedRabEstAttemptLackUl Ase (RAB failures -

Lack of UL ASE) pmNoFailedRabEstAttemptLackUl HwBest (RAB failures - Lack

of UL hardware resourcesBest cell) pmNoFailedRabEstAttemptLackDl HwBest (RAB failures - Lack

of DL hardware resourcesBest cell) pmNoFailedRabEstAttemptLackUl Hw (RAB failures -

Lack of UL hardware resources)

Number of failed RAB establishment attempts due to lack of DL channelization codes. Number of failed RAB establishment attempts due to lack of DL ASE Number of failed RAB establishment attempts due to lack of UL ASE Number of failed RAB establishment attempts due to lack of UL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of DL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of UL hardware resources.

UtranC ell

UtranC ell

UtranC ell UtranC ell

Counter

Description

Condition

MO Class

active set pmNoRabEstablishFailureUeCapa bility (RAB failures due

to UE Capability)

Number of failed RAB establishments due to insufficient UE capabilities

When the Ue Capability check fails for the state to which it is established, the counter is incremented.

UtranC ell

RNC/Market/Region Level Reporting These plots should be used as an indication of issues that should be investigated further on a Cell/RBS basis.

R99 RAB Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level. However, counters reporting R99 RAB Access failures are not being reported correctly by T-PIM currently, hence graphs to show this breakdown could not be prepared.

Worst Cells Analysis All of the mentioned metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level should be ranked by the following metrics: •

R99 interactive RAB access failures

•

R99 interactive RAB access failures – Radio Reasons

•

R99 interactive RAB access failures – Admission Control

•

R99 interactive RAB failures - Exceeded connection limit

•

R99 interactive RAB access failures–Node B/ TN Congestion

HSDPA Interactive RAB Accessibility HSDPA interactive RAB accessibility is also based on two counters which are pegged on the cell level in Serving RNC. These metrics can be run on Cell/RNC/Market/Region level. The counters are as follows: Counter

Description

Condition

MO Class

pmNoRabEstablishAttemptPacketInter activeHs (HS Interactive RAB

The number of attempted RAB establishmen ts for PS Interactive RAB mapped on HS-DSCH.

The counter is incremented after successful RAB Mapping when a RANAP RAB Assignment Request message is received from the CN with RABs to be setup or modified. The counters are reported per single RAB state after successful HS-DSCH selection on Serving HS-DSCH cell at RAB establishment for HS. The counter is stepped for the selected Serving HS-DSCH cell at RAB establishment after the successfully transition SRB-DCH to PS Interactive 64/HS - HSDSCH.

UtranCell

connection requests)

pmNoRabEstablishSuccessPacketInter activeHs (HS Interactive RAB

connection successes)

The number of successful RAB establishmen ts for PS Interactive RAB mapped on HS-DSCH.

UtranCell

Formula:

In Ericsson RNC, counters are available to breakdown some of HS interactive RAB Access failures to aid the troubleshooting of issues. All these single counter based KPI’s are available in T-PIM Accessibility detailed report.

HSDPA Interactive RAB Setup Failures Counters: (Pegged for HSDPA calls only) Counter

Description

Condition

MO Class

pmNoOfNonHoReqDeniedHs

Number of Interactive RAB establishments

Incremented by one when admission is

UtranCell

(HSDPA Interactive RAB

Counter

Description

Condition

Failures due to Admission Control)

on a (High Speed) HS configuration rejected by admission control.

rejected.

pmNoRabEstBlockNodePsInt HsBest (HS Int RAB Block

Number of RAB establishment attempts for RAB-type PS Interactive for HS that are blocked due to node congestion or node failure, counted on the best cell.

- Node Congestion/Failure (Best Cell)

pmNoRabEstBlockTnPsIntHs

(HS Int RAB Block - TN Congestion/Failure (Blocking cell)

pmNoRabEstBlockTnPsIntHsB est (HS Int RAB Block -

TN Congestion/Failure (Best Cell)

pmNoFailedREstAttExcConnLi mit (PS RAB failures -

Exceeded connection

Number of RAB establishment attempts for RAB-type PS Interactive for HS that are blocked due to TN congestion or TN failure, counted on the blocking cell.

Number of RAB establishment attempts for RAB-type PS Interactive for HS that are blocked due to TN congestion or TN failure, counted on the best cell.

Number of failed PS RAB establishment attempts due to exceeding the

Note: The counter is not incremented when admission is rejected in a DRNC cell. This counter is stepped when the establishment of a PS Interactive RAB for HS RAB fails due to node configuration error, node limitation or transport network layer service unavailability. This counter is stepped when the establishment of a PS Interactive RAB for HS, fails due to congestion on the user plane (AAL2) or control plane (UniSaal or SCTP) of the transport network layer as a result of user dimensioned transport network capacity. This counter is stepped when the establishment of a PS Interactive RAB fails due to UNI-SAAL or AAl2 congestion, IP resource limitations or blocking as a result of user dimensioned transport network configured capacity. The counter is stepped for the best cell in the active set but only if the cell is in the SRNC. Counter is stepped when admission control fails with reject reason value

MO Class

UtranCell

UtranCell

UtranCell

UtranCell

Counter

Description

Condition

limit)

configured connection limit when allocating Spreading Factor ('SF Histogram' in Admission Reject signal)

SF8, SF16, or SF32.

MO Class

The counter is stepped for the best cell in the active set in the SRNC for both R99 & HS RABs .

To calculate the values for HSDPA RAB failures due to radio reasons, we can use the following formula HS RAB access failures (Radio Reasons) = (Total HS RAB access failures) –(HS RAB Setup failures) Aadditional counters are also available to provide insight on RAB accessibility failures but these are pegged for both CS & PS RABS, hence a fair estimation is required to correlate these reasons to HS Interactive RAB access failures.

RAB Setup Failures Counters: (Pegged for CS + PS calls together) Counter

Description

Condition

MO Class

PmNoFailedRabEstAttemptLackDlPwr

Number of failed RAB establishment attempts due to lack of DL power

Counter is stepped when admission control fails with reject reason lack of DL power. Number of failed RAB establishment attempts due to lack of DL channelization codes. Counter is stepped when admission control fails with reject reason lack of DL ASE. Number of failed RAB establishment

UtranCel l

(RAB failures - Lack of DL power) pmNoFailedRabEstAttemptLackDlCh nlCode (RAB failures -

Lack of DL Channelization code)

Number of failed RAB establishment attempts due to lack of DL channelization codes.

PmNoFailedRabEstAttemptLackDlAse

Number of failed RAB establishment attempts due to lack of DL ASE

pmNoFailedRabEstAttemptLackUlAse

Number of failed RAB establishment

(RAB failures - Lack of DL ASE)

(RAB failures - Lack of UL

UtranCel l

UtranCel l

UtranCel l

Counter

Description

Condition

ASE)

attempts due to lack of UL ASE Number of failed RAB establishment attempts due to lack of UL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of DL hardware resources, for the best cell in the active set. Number of failed RAB establishment attempts due to lack of UL hardware resources.

attempts due to lack of UL ASE. The counter is stepped for the IubLink containing the best cell in the active set.

pmNoFailedRabEstAttemptLackUlHw Best (RAB failures - Lack of UL

hardware resources- Best cell)

pmNoFailedRabEstAttemptLackDlHw Best (RAB failures - Lack of

DL hardware resources- Best cell)

pmNoFailedRabEstAttemptLackUlHw (RAB failures - Lack of UL

hardware resources)

pmNoRabEstablishFailureUeCapabilit y (RAB failures due to UE

Capability)

Number of failed RAB establishments due to insufficient UE capabilities

MO Class

UtranCel l

The counter is stepped for the IubLink containing the best cell in the active set.

UtranCel l

The counter is stepped for the IubLink containing the first cell to fail admission in the active set When the Ue Capability check fails for the state to which it is established, the counter is incremented.

UtranCel l

UtranCel l

There 1 more counter available also which are pegged for both CS + PS calls and Setup + Radio access failures together. So, this counter can be used more for information & trending instead of troubleshooting. (already mentioned in CS RRC access failure part of this report)

RAB Failures Counter: (Pegged for CS + PS calls and Setup + Radio Access failures together) Counter

Description

Condition

MO Class

pmNoFailedAfterAdm

# RRC or RAB establishmen t requests failed after being admitted by admission control.

The counter is increased if a function that has been granted admission for a UE fails after being admitted due to a problem in the RRC or RAB Setup procedure. Then the admission control function must be informed about the release of previously requested resources due to the failed

UtranC ell

(RRC+RAB) Failures after Admission Control

(Please note this

Counter

counter also counts RAB failures)

Description

Condition

MO Class

procedure and this counter is increased. The

counter is increased in the cell or cells where the UE is located. This counter is stepped for all cells if UE is in macrodiversity. Note: The counter is not stepped for D-RNC cells or at failure of repeated RRC connection requests.

RNC/Market/Region Level Reporting This section covers analysis of HSDPA RAB Accessibility % for Ericsson UMTS network and identification of issues using the available Ericsson accessibility Counters.

HSDPA RAB Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level and can be shown as following.

0.0.0.1. HSDPA RAB Access failures Breakdown These metrics can be used to determine the breakdown of drops on an RNC, Market or Region level and can be shown as following.

HSDPARABAccessFailures 100%

HSRAB Radio AccessFailures

HSRAB Setup Failures

90% 80% 70% 60% 50% 40% 30% 20% 10%

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0%

Figure : HSDPA RAB’s accessibility was mostly influenced by Radio Access Failures. But after launching new sites on 2/1/2009, failures due to setup causes are also increasing . In the next chart, we would break up the causes for these setup failures to identify the prominent cause for such setup failures: HSDPARABSetupFailuresdistribution HSRABBlock

-NodeCongestion/Failure(Best Cell)

HSDPARABFailures_AdmControl

HSRABBlock

-TNCongestion/Failure(Blockingcell)

HSRABBlock

-TNCongestion/Failure(Best Cell)

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

Figure : “HS RAB failures due to Admission Control” is the main cause for HSDPA RAB setup failures, however “HS RAB failures due to Node Congestion” are also on rise in the last 2 days. Plotting the same causes in Bar format graph to show number of failures per reason.

HSDPARABSetupFailuresdistribution HSRAB Block -Node Congestion/Failure(Best Cell)

HSDPARABFailures_AdmControl

HSRAB Block -TN Congestion/Failure(Blocking cell)

HSRAB Block -TN Congestion/Failure(Best Cell)

12,000 10,000 8,000 6,000 4,000 2,000

/1 2 9 0 /2 1 9 0 /2 1 3 9 0 /2 1 4 9 0 /2 1 5 9 0 /2 1 6 9 0 /2 1 7 9 0 /2 1 8 9 0 /2 1 9 0 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 /1 2 9 0 /0 2 9 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 9 0 /9 2 0 9 0 /1 2 9 0 /1 2

0

Figure : “HS RAB failures due to Admission control” is the main cause for HSDPA RAB setup failures. As seen in Figure 14 &15 graphs, HS RAB failures due to Admission Control is the prominent cause for these HS RAB access setup failures, Hence in the next step, we would analyze those counters which are pegged in case of congestion / lack of resources in the cell to understand better the causes of this admission control. In the next chart, counters for Downlink path has been shown for clear visibility in the graph as RAB setup failures due to admission control are only in downlink & not in uplink.

RABSetupFailuresDistribution RABfailures - Lackof DL power RABfailures - Lackof DL ASE HSDPARABFailures_AdmControl_Usersallowed

RABfailures - Lackof DL Channelization code RABfailures - Lackof DL hardware resources

7,000 6,000 5,000 4,000 3,000 2,000 1,000

9 0 2 /1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 2 /0 1 9 0 /2 1 9 0 /2 1 9 0 2 /3 1 9 0 2 /4 1 9 0 2 /5 1 9 0 2 /6 1 9 0 2 /7 1 9 0 2 /8 1 0 2 /9 1 9 0 /2 1 9 0 /2 1 9 0 /2 1 9 0 3 /2 1 9 0 4 /2 1 9 0 5 /2 1 9 0 6 /2 1 9 0 7 /2 1 9 0 8 /2 1 0 9 /2 1 9 2 0 /3 1 9 0 2 /3 1 9 0 /1 2 9 /0 2 9 0 /3 2 9 0 /4 2 9 0 /5 2 9 0 /6 2 9 0 /7 2 9 0 /8 2 0 /9 2 9 0 /1 2 9 0 /1 2

0

Figure : “HS RAB setup failures due to Admission control triggered by number of users allowed in the cell” is the main cause for HS RAB setup failures. Although this chart highlights the limitation of HS Users allowed in the cell is the prominent cause triggering admission control for HSDPA RAB’s access failures, however attention must be paid to HSDPA RAB setup failures due to lack of Downlink Tx Power to troubleshoot all causes. In the next section, root causes for such failures have been explained.

HS RAB Setup Failure Causes a) HSDPA RAB Setup Failure Due to Admission Control Same as CS RRC admission control . However as explained, HSDPA Admission parameters settings limiting the number of users must be verified to baseline settings. b) HSDPA RAB Failures - NodeB Blocking (Best Cell) Same as CS RRC NodeB Blocking c) HSDPA

RAB Fails – Transport Network Blocking(Best cell) / (Blocked cell) Same as CS RRC Transport Network Blocking

d) HSDPA RAB Setup Failure Due to lack of DL/UL Tx power Same as CS RRC admission control e) HSDPA RAB Failures Due to lack of DL Channelization Codes Same as CS RRC admission control . However, along with checking Admission control parameters & OCNS activation status, channelization code (code tree) utilization trend must be checked to confirm the lack of resources. f) HSDPA RAB Failures Due to lack of DL / UL ASE Same as CS RAB Failures Due to lack of DL/UL ASE g) HSDPA RAB Setup Failure Due to lack of DL/ UL Hardware

Resources Same as CS RAB Failures Due to lack of DL/UL Hardware Resources h) HSDPA RAB Setup Failure Due to UE Capability

Same as CS RAB Failures Due to Ue capabilities.

HSDPA RAB Radio Access Failure Causes

a) HSDPA RAB Access Failure Due to Radio Reasons Same as CS RRC access failures due to MS

b) HSDPA RAB Access Failure Due to UE Failures Same as CS RRC access failures due to MS

c) Voice RAB Access Failure Due to RNC Internal Failures Same as CS RRC setup failures due to RNC

Worst Cells Analysis All of the mentioned metrics are pegged on Cell level. The Worst Offenders in an RNC/Market/Region level should be ranked by the following metrics: •

HS interactive RAB access failures

•

HS interactive RAB access failures – Radio Reasons

•

HS interactive RAB access failures – Admission Control

•

HS interactive RAB access failures–Node B/ TN Congestion

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

Admission Control Parameters

–

CS / Multi RAB Features implementation

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

Troubleshooting Tools The following tools can be used for troubleshooting: •

GPEH  The General Performance Event Handling (GPEH) tool is a feature in Ericsson OSS that provides capability similar to a protocol analyzer. This also has visibility of internal RNC events such as Missing neighbour etc  This can be run on an RNC level  More detail on this tool can be found in ALEX

•

CTR  The Call Trace (CTR) tool is a feature in Ericsson OSS that provides capability similar to the GPEH Tool  This can be run on a Cell level for specific cell troubleshooting. These files can be read in Actix  More detail on this tool can be found in ALEX

•

UETR  The User Equipment Trace (UETR) tool is a feature in Ericsson OSS that provides capability similar to the GPEH Tool  This is run on a particular IMSI for specific issue troubleshooting, typically a test SIM attempting to recreate problem conditions. These files can be read in Actix  More detail on this tool can be found in ALEX