Informacion 3G

1 © Nokia Siemens Networks Presentation / Author / Date

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Telefónica Perú

Capacity Management 3G Network


For internal use

Outline

• Introduction

• Capacity Areas in UTRAN1. Air Interface

2. WBTS HW Resourses

3. RNC

4. Transport IuB

• Iu Monitoring• Iu-CS

• Iu-PS

• Iu-R


For internal use

Introduction

WCDMA network interfaces and internal resources should be monitored


For internal use

Introduction

• The various measurement were used to identify the capacity issues and their negative impact on accessibility (CSSR) of the various RABs:

1. CS speech (AMR)

2. PS data (R99)

3. HSPA data


For internal use

Capacity Areas in UTRAN

• Essential to monitor the available resources in UTRAN

– Capacity from initial dimensioning phase may no be sufficient in some cases

– Marketing campaigns lead to higher resource utilization

• Capacity bottlenecks impact the call setup success rates (CSSR)

– Mobile user perceives poor setup success rates directly

• With these measurements, network capacity can be monitored in a proactive mode

– Capacity upgrades can be triggered taking into account existing lead times HW units, internal procedures like planning or implementation


For internal use

IuB

Air Interface WBTS HW Resources Transport

UL interference

DL transmisson power

DL Codes

FSP/ WSP capacity (N*) E1 capacity / AAL2

Capacity Areas in UTRAN

RLC/MAC

During call set-up [RRC, RAB] several resource areas are checked and

physical / logical resources allocated.

DSP processing

RNC

1 – Radio resources

1a – Code resources

2 – WBTS resources (Channel Elements)

3 – DMCU

allocation

4 – Iub resources(transmission)


For internal use

Call Setup Success Rate - CSSR

CSSR for a specific service is calculated the following way:

For RAB setup & access phase we can distinguish various failure causes:

CSSR any service = RRC connection setup & access X RAB setup & access any service

RRC part RAB part

SETUP PHASE:

• due to AC

• due to BTS

• due to Transport

• due to RNC

• due to Frozen BTS

• due to AAL2 iuB, License, AAL2 IuCS, anchoring, UE

capabilities, not supp. params

ACCESS PHASE:

• due to UE

• due to RNC

Failures due to UE

• are not related to capacity issues in the

network

• related to UE problems


For internal use

Decision criteria

Accesibility < 99%

Cell OK

No

Yes

Additional KPI check & optimization (if necessary)

• AMR accessibility

• PS R99 accessibility

• HSPA accessibility

Radio

resourcesChannel

elements

Transport

resources

RNC internal

resources

Lack of

Radio Resoures

Lack of

Channel Elements

Lack of

Iub resourcesLack of

RNC resources

Failures due to

AC >1%

Failures due to

BTS >1%

Failures due to

TRANS >1%

Failures due to

RNC >1%


For internal use

RAB setup failures1. Admission Control (AC) failures – RADIO

• Indicates lack of radio resources:– DL power

▪ Measurement of PtxTotal, transmission power of NonHSDPA, HSDPA etc.

– UL interference

▪ Measurement of RSSI

▪ Measurement of PrxTotal and PrxNoise

– DL channelization codes:

▪ Channelization code occupancy (min, max, avg)

▪ Channelization code blocking rate

▪ HSDPA code usage

▪ HSDPA code downgrades

– Rejection rate in downlink and uplink (SRB, AMR, CS data, PS data) due to congestion

– Common channel load (RACH, FACH, PCH) – typically not a problem


For internal use

RAB setup failures1. Admission Control (AC) failures – RADIO

Posible to

reduce the

code usage?

Upgrade

BTS power

High UL

interference/loadPosible to reduce

R99 usage?

High non-

HSPA load

High non-

HSPA load

Posible to

optimize

throughput?

Upgrade

to 2nd carrier

‘

DL power

Marginal Load Time Share DL > 50%

Overload Time Share DL> 2%

Average DL R99 Load > PtxTarget

Marginal Load Time Share UL > 50%

Overload Time Share UL> 2%

Average UL R99 Load > PrxTarget

Noise floor of the System

>-90dBm

High DL load

Failures due to

AC >1%

R99 power >> HSDPA power

No

Yes

Yes

No

UL interference

Spread. Code Blocking Rate in DL

>5%;

SFxx Blocking Rate high

Max_Code Occupancy >95%;

Avg_Code Occupancy >80%

Channelization

codes

High chan. Code

utilization

No

• AMR accessibility

• PS R99 accessibility

Yes

External

Interference


For internal use

RAB setup failures1a. HSDPA accessibility

• Indicates problems for access of HS-DSCH (HSDPA access failure rate):

1. Due to UL DCH

• Problems of return UL return channel

• Related to R99 radio resources

2. Due to TOO MANY HSDPA USERS

• Licence limit – 48 users HSDPA license upgrade to 64 users

• R99 is selected, which can cause capacity problem in use of radio resources Check radio resources for R99

• If licence upgrade is not sufficient, the Dedicated HSDPA scheduler is an option

3. Due to BTS (channel elements)

4. Due to Iub (transmission)

5. Due to RNC


For internal use

RAB setup failures1a. HSDPA accesibility

HSDPA

accessibilit

y < 99%

Go to

RADIO

Resoures

Go to

BTS failures

Go to

RNC failures

Go to

TRANSPORT

failures

1. HSDPA 64 users

License upgrade

Problem in

R99 ?

2. HSDPA Dedicated

Scheduler upgrade

HSDPA Access FR

due to UL DCH

HSDPA Access

FR due to RNC

HSDPA Access

FR due to BTS

HSDPA Access

FR due to Iub

OR LATER

Radio related issues

Others

DCH Selected

due to too many

HSDPA users

> 0.5%


For internal use

RAB setup failures2. BTS failures

• Indicates lack of WBTS baseband resources = channel elements (CE):

– Measurement of available CEs (min, max, avg)

– Measurement of usage of CEs:

▪ In UL, DL (min, max, avg)

▪ Per service

WBTS HW upgrade

(system module)

CE usage

can be

reduced?

No

Yes

Fast Failures due to

BTS >1%

AVG_CE_USAGE > 80%

MAX_CE_USAGE >95%

High CE utilization

CE utilization


For internal use

RAB setup failures3. RNC failures

• Indicates lack of RNC internal resources

– DSP Service Statistics Measurement

– DSP Resource Utilisation Measurements

– DSP State Change Measurements

– DSP Load Measurements

– Iub, IuCS, IuPS throughput measurement at RNC

RNC HW upgrade

Fast

RNC Interface

capacity upgrade

Failures due to

RNC >1%

High DSP load

RNC_Unit Load:

AVG_Load >80%

MAX_Load >95%

DSP load

RNC_Traffic Load:

Iub Traffic Load

IuCS Traffic Load

IuPS Traffic Load

High Iu Traffic

Traffic load


For internal use

RAB setup failures4. Transport failures

• Indicates lack of transport resources

– Traffic load measurements

▪ Average VCC Ingress/Egress utilisation

▪ Average VPC Ingress/Egress utilisation

– CAC reservations

▪ Allocated Average Capacity of CBR VCC

▪ Allocated Capacity per ATM VCC (cps)

▪ AAL2 connection reservation success rate

– Number of AAL2 Connections

▪ Average AAL2 connection utilisation

▪ Max_AAL2_connections (248 max)

▪ Max_AAL2_connections_HSPDA

– Shared HSDPA AAL2 allocation utilisation Iub upgrade

Posible to

reduce Iub

utilization?

Yes

No

Yes

Fast Failures due to

TRANS/AAL2 Iub >1%

AVG_UP_CAC Reservation > 80%

Peak_UP_CAC Reservation >90%

High Iub load

Iub Reservations


For internal use

Additional tasks

• Even if all the capacity issues would be resolved, the 100% accessibility can not be expected

• RF optimization (e.g. overshooting cells)

– Propagation delay measurements

– CQI measurements

– RSCP, Ec/Io measurements

• Mobility optimization

– Soft handover

– Inter-system handover

• Failures due to UEs can not be avoid


For internal use

Iu Monitoring

• The scope of this presentation is RNC interfaces monitoring using measurements in the RNC and in the BTS

Iu-CS

Iu-PS

Iur

RNC BTS

RNC

MGW

SGSN

Iub


For internal use

Content

1. ATM load measurements

2. AAL2 CAC measurements


For internal use

ATM Load Measurements - Overview

ATM Load Measurements in RNC

• Virtual Path Connection (VPC)

• Virtual Circuit Connection (VCC)

• ATM interfaceA

TM

inte

rface

Virtual path

Virtual path

Virtual channel

AAL2

connection


For internal use

ATM VPC and VCC Measurements

• ATM VPC/VCC measurements count cells per VPC/VCC during measurement period

• Up to 1024 VPCs and all VCCs (RU10 onwards) can be measured per RNC at the same time

• Enables calculating average throughput over the measurement period

Configured capacity

Measurement period

Cells/period

Actual traffic

Measured average traffic


For internal use

ATM VPC and VCC Measurements

• Iu-CS, Iu-PS and Iur can be measured as well

• Use of ingress and egress counters

– Iub in downlink direction is measured using egress counters

– Iu-PS in downlink direction is measured using ingress counters

Iu-CS

Iu-PS

Iur

RNC BTS

RNC

MGW

SGSN

Iub

Egress

directionIngress

direction


For internal use

ATM Interface Measurement

• ATM interface utilization and traffic per service category CBR, UBR and UBR+

• The ATM interface level measurement is relevant if you have unshaped VPCs with UBR+ VCCs inside and the sum of VCC PCRs exceeds the interface capacity

– Otherwise the ATM CAC and/or VCC/VPC configuration will prevent overload possibility

• Potentially useful for Iu if IuPS and IuCS are on their own NIS cards.

AT

M inte

rface

Virtual path

Virtual path

Virtual channel

AAL2

connection


For internal use

Content

1. ATM load measurements

2. AAL2 CAC measurements


For internal use

RNC AAL2 Connection Admission Control

• Bandwidth requirement is affected by

– ALC parameters, ALC set (for DCCH), Activity factors

– Delay requirement, loss tolerance

– Done for common channels, SRB, RT DCH, NRT DCH, Streaming HSDPA and SharedHSDPAAllocation

– VCC bundle is a special case

ATM

VCC

PCRAAL2 reservation

for existing

connections

New

connection

requiring

this much

capacity

would be

blocked

New

connection

up to this

capacity

would fit in


For internal use

Summary

RAN capacity monitoring processes are focused on the following interfaces and network elements:

• Radio Interface capacity – WBTS power, code tree

• Iub capacity – Transmission capacity

• Node B capacity –WBTS Base band processing capacity

• RNC processing capacity

• Iu-CS, Iu-PS and Iur traffic

RNC Capacity

-RNC traffic load

-Unit load

-Setup failure due to RNC

Proactive Monitoring

Reactive Monitoring

-BTS power DL/UL

-Channelisation code utilisation

-S-CCPCH & PRACH load

-Setup failure due to AC

-Service rejection ratio

-Code blocking

-RB downgrade/release

Monitoring / Interface Air Interface Iub Interface HW Channel Element

-Setup failure due to

transmission

-Resource reservation success

rate

-Iub traffic load

-Resource reservation -CE utilisation

-Setup failure due to BTS


For internal use


For internal use

Thank You!

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Informacion 3G