intro to quality of service & traffic load monitoring b10.pdf

7/28/2019 Intro to Quality of Service & Traffic Load monitoring B10.pdf

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Introduction to Quality of Service and Traffic Load Monitoring - B10 - Page 1All Rights Reserved 2007, Alcatel-Lucent

All rights reserved 2007, Alcatel-Lucent

EVOLIUM Base Station Subsystem - Introduction to Quality of Service and Traffic Load Monitoring - B10

EVOLIUM Base Station SubsystemIntroduction to Quality of Service

and Traffic Load Monitoring - B10

TRAINING MANUAL

3FL10491ADAAWBZZAEdition 01

Copyright 2007 by Alcatel-Lucent - All rights reserved

Passing on and copying of this document, use andcommunication of its contents not permitted withoutwritten authorization from Alcatel-Lucent


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All Rights Reserved Alcatel-Lucent 2007

EVOLIUM Base Station Subsystem

Introduction to Quality of Service and Traffic Load

Monitoring - B10

2

Legal Notice

Switch to notes view!Safety Warning

Both lethal and dangerous voltages are present within the equipment. Do not wear conductive jewelry

while working on the equipment. Always observe all safety precautions and do not work on theequipment alone.

Caution

The equipment used during this course is electrostatic sensitive. Please observe correct anti-static

precautions.

Trade Marks

Alcatel and MainStreet are trademarks of Alcatel.

All other trademarks, service marks and logos (Marks) are the property of their respective holders

including Alcatel-Lucent. Users are not permitted to use these Marks without the prior consent of Alcatel

or such third party owning the Mark. The absence of a Mark identifier is not a representation that a

particular product or service name is not a Mark.

Copyright

This document contains information that is proprietary to Alcatel-Lucent and may be used for training

purposes only. No other use or transmission of all or any part of this document is permitted without

Alcatel-Lucents written permission, and must include all copyright and other proprietary notices. No

other use or transmission of all or any part of its contents may be used, copied, disclosed or conveyed to

any party in any manner whatsoever without prior written permission from Alcatel-Lucent.

Use or transmission of all or any part of this document in violation of any applicable Canadian or other

legislation is hereby expressly prohibited.

User obtains no rights in the information or in any product, process, technology or trademark which itincludes or describes, and is expressly prohibited from modifying the information or creating derivative

works without the express written consent of Alcatel-Lucent.

Alcatel-Lucent, The Alcatel-Lucent logo, MainStreet and Newbridge are registered trademarks of Alcatel-

Lucent. All other trademarks are the property of their respective owners. Alcatel-Lucent assumes no

responsibility for the accuracy of the information presented, which is subject to change without notice.

2007 Alcatel-Lucent. All rights reserved.

Disclaimer

In no event will Alcatel-Lucent be liable for any direct, indirect, special, incidental or consequential

damages, including lost profits, lost business or lost data, resulting from the use of or reliance upon the

information, whether or not Alcatel has been advised of the possibility of such damages.

Mention of non-Alcatel-Lucent products or services is for information purposes only and constitutes

neither an endorsement nor a recommendation.

Please refer to technical practices supplied by Alcatel-Lucent for current information concerning Alcatel-

Lucent equipment and its operation.


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EVOLIUM Base Station SubsystemIntroduction to Quality of Service and Traffic Load

Monitoring - B10

3

Table of Contents

Switch to notes view!1. GSM QoS Monitoring

1. Introduction

2. Global Indicators

3. Detailed Indicators

4. Handover Indicators

5. Directed Retry Indicators

6. Radio Measurement Statistics Indicators

7. Traffic Indicators

8. Case Studies

9. Annexes


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Monitoring - B10

4

Table of Contents [cont.]

Switch to notes view!

This page is left blank intentionally


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Monitoring - B10

5

Course Objectives


Welcome to Introduction to Quality of Service and Traffic Load Monitoring - B10

After successful completion of this course, you should understand:

Global indicators, in order to assess the general quality of the network

Detailed indicators, in order to detect / identify / locate the main malfunctions

Handover indicators, in order to quantify efficiency and reason of HO

Directed retry indicators, in order to quantify efficiency of directed retry

RMS indicators to ease radio optimization and fault detection

Traffic indicators, in order to detect/predict overload and compute adequate celldimensioning as well as to understand how RTCH resources are used in the network


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Monitoring - B10

6

Course Objectives [cont.]




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Monitoring - B10

7

About this Student Guide

Switch to notes view!Conventions used in this guide

Where you can get further information

If you want further information you can refer to the following:

Technical Practices for the specific product

Technical support page on the Alcatel website: http://www.alcatel-lucent.com

Note

Provides you with additional information about the topic being discussed.

Although this information is not required knowledge, you might find it useful

or interesting.

Technical Reference(1) 24.348.98 Points you to the exact section of Alcatel-Lucent Technical

Practices where you can find more information on the topic being discussed.

WarningAlerts you to instances where non-compliance could result in equipment

damage or personal injury.


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Monitoring - B10

8

About this Student Guide [cont.]




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Monitoring - B10

9

Self-Assessment of Objectives

At the end of each section you will be asked to fill this questionnaire

Please, return this sheet to the trainer at the end of the training


Instructional objectives

Yes (or

globallyyes)

No (or

globallyno)

Comments

Contract number :

Course title :

Client (Company, Center) :

Language : Dates from : to :

Number of trainees : Location :

Surname, First name :

Did you meet the following objectives ?

Tick the corresponding box

Please, return this sheet to the trainer at the end of the training


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Monitoring - B10

10

Self-Assessment of Objectives [cont.]


Instructional objectivesYes (orGlobally

yes)

No (orglobally

no)Comments

Thank you for your answers to this questionnaire

Other comments


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Section 1 Module 1 Page 1


3JK11043AAAAWBZZA Issue 01

Do not delete this graphic elements in here:

11All Rights Reserved Alcatel-Lucent 2008Module 1

Introduction3JK11043AAAAWBZZA Issue 01

Section 1GSM QoS Monitoring

EVOLIUM Base Station SubsystemIntroduction to Quality of Service and Traffic Load Monitoring - B10

3FL10491ADAAZZZZA Issue 01


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EVOLIUM Base Station Subsystem Introduction to Quality of Service and Traffic Load Monitoring - B10GSM QoS Monitoring Introduction

1 1 2

Blank Page


First editionLast name, first nameYYYY-MM-DD01

RemarksAuthorDateEdition

Document History


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1 1 3

Module Objectives

Upon completion of this module, you should be able to:

Explain what is QoS and Traffic Load monitoring of the BSS Explain what are the information sources available for that purpose


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1 1 4

Module Objectives [cont.]



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1 1 5

Table of Contents

Switch to notes view!Page

1 Monitoring the QoS of the BSS 72 Monitoring the Traffic Load of the BSS 10

3 Information Sources Available 124 Introduction to K1205 PC Emulation 28


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1 1 7

1 Monitoring the QoS of the BSS


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1 1 8


Definition

"Monitor" "network" "quality"

monitor = measure or ensure?

network = BSS? BSS+NSS? BSS+NSS+PSTN quality = service (end-user) and/or system (technical)

But also detect, localize, diagnose outages

detect (decide according to thresholds)

localize (which cell, BSC, etc.)

diagnose: radio, BSS, TC problems


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1 1 9


Usage

QoS ResultsQoS Results

Management network monitoring comparison with competitor

comparison of manufacturers

contractual requirement: licence

quality responsible

Management network monitoring

comparison with competitor

comparison of manufacturers

contractual requirement: licence

quality responsible

Radio optimization cell radio quality survey

HO quality monitoring assessment of tuning efficiency

Radio optimization cell radio quality survey

HO quality monitoring

assessment of tuning efficiency

BSS maintenance cell/BSC/TC problem detection

BSS maintenance cell/BSC/TC problem detection

3 usages of QoS data 3 levels of QoS reports:

1. Management team: has to compare Network QoS with competitors' one and to plan Network evolutions.

needs to have a general view of the Network QoS on a monthly (and sometimes weekly) basis.

2. Radio Optimization team: has to detect bad QoS areas in the network and to implement and assess

modifications for QoS improvement.

needs to have a detailed status and evolution of the QoS at BSS and cell (and sometimes TRX) levels on

a weekly, daily (and sometimes hourly) basis.

3. Supervision and Maintenance team: has to detect dramatic QoS degradations and identify the responsible

Network Element (and if possible component).

needs to have the most detailed status of QoS at cell and TRX levels on an hourly basis.


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1 1 10

2 Monitoring the Traffic Load of the BSS


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2 Monitoring the Traffic Load of the BSS

Definition

Measure the "quantity" of traffic handled by:

the network

the BSCs the cells

Analyze traffic characteristics

call, handover, location update, etc.

As input for dimensioning/architecture team


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1 1 12

3 Information Sources Available


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Observation Means

DIFFERENT WAYS TO OBSERVE/MEASURE the GSM network

External Interface Analysis

A interface: MSC/TC-BSC

Abis interface: BSC/BTS

Air MS/BTS

Counter browser

OMC Counters

BSC

(NSS)

Tektronix K1205

Gnnettest MPAW&G NPA

QoS data can be built up from different and complementary kinds of information sources.

Usually post-processing applications will build up QoS indicators from:

OMC-R counters provided by the BSS system itself.

Signaling messages provided by a protocol acquisition tool on the different interfaces handled by the BSS:

Air, Abis, A (or Ater).


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A Interface Trace

INFORMATION SOURCE: EXTERNAL INTERFACE "A"

Capture/decode signaling between MSC and BSC-TC (A or Ater MUX)

with "protocol analyzer" (Wandel, Tektronix, Gnnettest, etc.)+ GSM standard, can be used for arbitrage between manufacturers

+ Complete information (message contents, time-stamp)

+ Possible detection of User/MS/BSS/TC/NSS problems

- High cost of equipment

- Time consuming, "post mortem" (installation of tool, file analysis)

- Expertise needed for analysis

- Low coverage (K1103/MA10: 8 COCs, K1205/MPA: 32 COCs maximum!)

- Large amount of data (>> 10 Mbytes /hour/BSC)

The main advantage of the A interface is to allow the detection of Call Setup failures either due to the User

or to the NSS (or PSTN).

Some typical user failure causes are: Some typical NSS failure causes are:

IMSI Unknown in VLR Temporary Failure

IMSI Unknown in HLR Resource Unavailable

IMEI Not Accepted Switching Equipment Congestion

PLMN Not Allowed Normal Unspecified

Service Option Not Supported Recovery on Timer Expiry

Requested Service Not Supported Call Reject

Unassigned Number Interworking

Operator Determined Barring Protocol Error

User Alerting Network Failure

Facility Not Subscribed Congestion

No Route to Destination

Normal Call Clearing

User Busy

Invalid Number Format

Call Reject

Interworking

Normal Unspecified

CAUTION: In order to assess the QoS of a BSS or some cells of a BSS, all N7 links between this BSC and the

MSC must be traced. Indeed, as the N7 signaling load is spread over all N7 links, signaling messages relating

to one call can be conveyed on any of the active N7 links.

K1103 protocol analyzer can trace up to 8 COCs at the same time but on maximum 4 PCM physical links.

K1205 protocol analyzer can trace up to 32 COCs at the same time but on maximum 16 PCM physical links.


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Example of Trace

On a K1205 protocol analyzer


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Abis Interface Trace

INFORMATION SOURCE: EXTERNAL INTERFACE "Abis"

Capture/decode signaling between BSC and BTS with "protocol

analyzer" (Wandel, Tektronix, Gnnettest, etc.)+ Complete information (message contents, time-stamp)

+ Possible detection of User/MS/BSS/TC/NSS problems

+ Complete radio information thanks to measurement messages

+ Downlink and uplink


- Time consuming, "post mortem" (installation of tool, file analysis)

- Important expertise needed for analysis

- Very low coverage (A few RSLs, a few cell(s))- Very large amount of data (>> 10 Mbytes/hour/BTS)

The main advantage of the Abis trace is to allow a detailed and precise assessment of the radio quality of a

cell at TRX level. Both DownLink and UpLink paths can be observed and compared.

BUT from B7 release, the Radio Measurement Statistics (RMS) feature implemented in the BSS provides a

good level of information allowing to reduce the number of Abis traces to be done for radio network

optimization.


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Air Interface Trace

INFORMATION SOURCE: EXTERNAL INTERFACE "Air"

Use trace MS to capture signaling and signal characteristics

+ Give precise location (x,y) of problems+ Give downlink radio information

+ Only way to localize a lack of coverage

+ Only way to monitor competitor


- Very time-consuming

- Difficulty to perform a lot of calls

-> number of samples insufficient

-> only a few streets- No uplink

The main advantage of the Air trace is to associate a radio quality measurement to a given geographical

area of the network.

Even if the RMS feature will allow to assess the radio quality as perceived by the end user, no location of

the radio problems is provided through the RMS.


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1 1 18


Performance Measurement Counters

SUB-SYSTEM COUNTERS

Count events seen by sub-system, value reported periodically

(1 hour)

+ Low cost: collected directly at OMC

+ Compact data: possibility to store counters for a complete network

- Raw information, having to be consolidated to be understandable

- Manufacturer's dependent: questionable/difficult to compare

- Weak to analyze other sub-systems

The main advantage of the BSS counters is to provide easily QoS data for permanent QoS monitoring.


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Exercise

Draw the BSS PM counters flow on the chart

In which sub-system are the BSS QoS indicators computed and stored?

BSC

BSC

BSC

OMC-R

OMC-R OMC-R

NPA

RNO


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1 1 20


BSS Counters

Combined into significant formulae: indicators

Used to monitor BSS network quality

Over a complete network, with breakdown per cell/BSC

SPECIFIC DRAWBACK

NSS/PSTN/MS/USER problems not seen

As BSS PM counters are defined in order to provide information to assess the QoS of the BSS and help to

detect BSS misbehavior, there is no way to identify QoS problems due to NSS, PSTN or User.


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NSS Counters

Combined into significant formulas: indicators

Used to monitor NSS network quality

Over a complete network, with breakdown per BSC (maximum)

SPECIFIC DRAWBACKS

BSS problems usually not precisely identified

No breakdown per cell

The NSS QoS is provided through NSS PM counters and indicators. It is out of the scope ot this training

course.


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Alcatel-Lucent BSS Counters

INFORMATION SOURCES: BSS Counters (1/2)

Performance Management implementation

Easy and cost-effective way to monitor network and carried traffic Principle:

For a given duration (granularity period= typically 1 hour)

To count pre-defined events occurring on the Abis or A interface, orinternally.

Counters stored with breakdown per network component (i.e. cell)

In the BSS B9, around 1000 counters are available (without GPRS).

Alcatel-Lucent has chosen to implement PM counters in the BSC and to increment them mostly on Abis

interface signaling messages.

Other suppliers may have chosen to increment them on A interface signaling messages or to implement

them in the BTS.

Therefore caution should be taken when interpreting QoS indicators value since some discrepancies may be

observed due to these possible choices.

In order to provide the operators with an easy and cost-effective way to monitor their network and carried

traffic, BSS manufacturers have implemented specific software features, called performance management.

The principle is to count for a given duration called granularity period (typically 1 hour) pre-defined events

occurring on the Abis or A interface, or internally. These counters are stored for each duration, with

breakdown per network component (i.e. cell).


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Alcatel-Lucent BSS Counters [cont.]

INFORMATION SOURCES: BSS Counters (2/2)

In Alcatel-Lucent BSS (except GPRS), counters are computed by the

BSC, based mainly on Abis messages. Every reporting period, counters values are sent to the OMC-R for

storage.

Several counters are reported to the OMC-R permanently every PMgranularity period:

Type 180: per cell adjacency

Type 110 per cell

Other Types: per TRX / N7 Link / BSC /

Millions of counters are collected every day


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BSS Counter Example

MC718:counter number

NB_TCH_NOR_ASS_SUCC_TRX: counter name Cumulative: method of computation

Type 110: BSS PM measurement type to which the counter belongs

Measured object: minimum object level for which the counter isprovided: TRX or CELL or BSC or N7 LINK or X25 LINK etc.

All counters are described in PM Counters and Indicators.


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BSS Counter Characteristics

Collection mechanism

Cumulative The counter is incremented at the occurrence of a specific event.

Abis or A message, or internal event.

At the end of a collection period, the result is the sum of the events.

Inspection

Every 20 or 10 seconds, a task quantifies an internal resource status (usuallya table).

At the end of a collection period, the result is the mean value.

Observation

Set of recorded information about a telecom procedure (handover, channelrelease, UL & DL measurements reporting).

Main counters are of cumulative type.

Inspection counters are of gauge type.

Observation counters are grouped in a Performance Measurement record associated to a particular GSM BSS

telecom procedure: SDCCH channel seizure, TCH channel seizure, internal handover, etc.


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BSS Performance Measurement TypesB10

N Type Name Type definition

1 Traffic Measurement Set of counters related to the traffic evaluation per telecom procedure

2 Resource Availability Measurement Set of counters related to the availability of the CCCH, SDCCH, or TCH channels

3 CCCH channel resource usage measurements Set of counters related to the usage of CCCH channel (PCH, AGCH, RACH)

4 SDCCH channel resource usage measurements Set of counters related to the usage of SDCCH channel

5 TCH channel resource usage measurements Set of counters related to the usage of TCH channel6 TCH Handover Measurements Set of counters related to the TCH handover procedure

7 LAPD Measurement Set of counters related to the LapD logical links

8 X.25 Measurement Set of counters related to the X25 links OMC-BSC

9 N7 Measurement Set of counters related to the N7 Signaling Links

10 SDCCH Observations Observation counters on SDCCH channels allocated

11 TCH measurements observations Observation counters on 08.58 MEASUREMENT REPORT for a TCH

12 Internal Handover Observations Observation counters on internal intra-cell or inter-cell SDCCH or TCH handover

13 Incoming External Handover Observations Observation counters on incoming external SDCCH or TCH handover

14 Outgoing External Handover Observations Observation counters on outgoing external SDCCH or TCH handover

15 TCH Observation Observation counters on TCH channel allocated

18 A Interface measurements different causes of 08.08 CLEAR REQUEST and 08.08 ASSIGNMENT FAILURE

19 SMS PP Measurements Set of counters related to Short Message Service Point to Point

25 SCCP Measurements Set of counters related to SCCP Layer of the N7 signaling Links

26 TCH outgoing Handover per adjency Set of counters related to outgoing TCH handover provided per adjency

27 TCH incoming Handover per adjency Set of counters related to incoming TCH handover provided per adjency

28 SDCCH Handover Set of counter related to the SDCCH handover procedure29 Directed Retry measurements Set of counter related to the directed retry handover procedure

30 SMS CB Meas urements Set of counters related to Short Message Service Cell Broadcast

31 Radio Measurement Statistics Set of counters providing radio quality measurements for TRX/Cell

32 Change of frequency band measurements Set of counters related to handovers including a change of TCH Frequency band

33 BTS Power Measurement Average emitted power at the BTS antenna output

110 Overview measurements Set of key counters allowing to access Quality of Service of a given Cell/BSC/Network

180 Traffic Flow measurements Set of counters related to incoming inter-cell SDCCH/TCH handover performed per adjencyANNEX 6Modified B10

BSS Performance Measurement types (PM types) are split into two categories:

standard types (7, 8, 9, 18, 19, 25, 28, 29, 30, 31, 32,110, 180)

detailed types (1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 15, 26, 27)

The most important types for QoS monitoring and Radio Network Optimization are in bold.

A standard PM type can be activated for the whole network. It means that the related counters are

reported for all the Network Elements they are implemented on (TRX, CELL, N7 link, X25 link, LAPD link,

Adjacency).

A detailed PM type can be activated only on a sub-set of the network. It means that the related counters

are reported only for a limited number of Network Elements:

40 cells per BSS for PM types 1, 2, 3, 4, 5, 6, 26, 29

15 cells per BSS for PM types 10, 12, 13, 14, 15

1 cell per BSS for PM types 11, 27

Counter numbering rules:

Cyz: cumulative or inspection counters in PM types 1, 2, 3, 4, 5, 6, 18, 19, 25, 26, 27, 28, 29, 30, 32, 180

Ly.z: cumulative counters in PM type 7 (L stands for LAPD link)

Xy.z: cumulative counters in PM type 8 (X stands for X25 link)

Ny.z: cumulative counters in PM type 9 (N stands for N7 link)

Syz: observation counters in PM type 10 (S stands for SDCCH)

Ryz:: observation counters in PM type 11 (R stands for Radio measurements)

HOyz: observation counters in PM type 12, 13, 14 (HO stands for HandOver)

Tyz: observation counters in PM type 15 (T stands for TCH) RMSyz: cumulative counters in PM type 31 (RMS stands for Radio Measurement Statistics)

MCyz or MNy.z: cumulative counters in PM type 110 (M stands for Major)


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1 1 27


Exercise

Observation Means: find the best source of information.Observation to be done: Best source Why

6- history of network quality for several

weeks

8- discriminate problems between BSS/NSS.

BSS and NSS coming from differentproviders

9- In a building, one is thinking that an

elevator is inducing PCM trouble, how to

confirm ?

10- Identify potential interfering cells of 1

Cells

5- localise abnormal cells in a network

7- compare networks quality

3- get average network quality

4- localise precise location of a radio pb

1- overall radio quality of 1 cell Counters Type 31: RMS

2- monitor user failures


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4 Introduction to K1205 PC Emulation


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Usage

The trace done with K1205 can be read:

Directly on K1205 itself

On any PC Windows NT with dedicated emulation software

Practical exercises will be done during the course using this software

The following slides and exercises are here to teach you the basic skillneeded to operate the tool for A Interface decoding


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Measurement Scenarios Screen

To select binarytrace file

To select binarytrace file

To enter in

monitoring mode to

analyze the

A trace

To enter in

monitoring mode to

analyze the

A trace

To filter the main

GSM protocols and

messages

To filter the main

GSM protocols and

messages

1. Start the K1205 Protocol Testerapplication.

2. In the Recording File box: click on the Open button and select the "PAIB29.rec" file.

3. Select all displayed N7 logical links (corresponding to 4 PCMs in this case).

4. Click on the Browse button and select gsm2_A.stk in the gsm2 sub-directory (corresponding to the GSMPhase 2 A interface protocol stack).

5. Click on OK.

6. Click on theMonitorbox to display the content of the recorded trace.


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Filter Configuration

Configure your filter to remove some messagesand protocols => Bypass Protocol Filter

and select:

SCCP Except UDT

Keep all DTAP

BSSM Except PAGIN

Select also allLogical Links

ANNEX 4

The ANNEX 4 introduces some basics on the GSM protocol layers that will be traced for the A interface

analysis.

UDT: Unit Data (for Signaling Control Point) Remove Paging information


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Monitor Screen

Short View

1 line / message

Short View

1 line / message

Frame View

Full decoding of

selected message

Frame View

Full decoding of

selected message

Packet view

Message content

in hexadecimal

Packet view

Message content

in hexadecimal

To extract 1 callTo extract 1 call


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Extract a Call

How to find a specific message?

Edit - Find (or ctrl + F3)

Select All Logical Links. Choose the protocol.

Select the message studied.

Use F3 to find another same message.

How to extract a call from these traces?

Click on the Zoom button.

Select CC message (Connection Confirm).

And UnZoom + Zoom to get:

SLR: Source Location Reference

LR: Destination Location Reference

At call setup, the first signaling message on the A interface is sent by the BSC to the MSC in order to set up

a logical link (called SCCP connection) between the BSS and the NSS.

Both BSS and NSS entities choose a unique reference which has to be used by the other party to identify the

SCCP connection on which the messages are conveyed. Both BSS reference (xxx) and NSS reference (yyy)

are exchanged during the SCCP Connection Request and Connection Confirm phases. After that only the

reference of the other party is used.


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Call Extraction

Then

Click on the Filterbutton and filter out all protocol layers and messages except:

all DTAP messages,

all BSSMAP messages except "Paging,

SCCP CR (Connection Request) and CC (Connection Confirm) messages.


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1 1 35


Exercise

Use the tool to extract a few calls from file PAIB29.REC

1) Zoom on a CC message:

Find the definition of all messages in the Frame View.2) Zoom on a CR message with LUREQ.

How to extract the complete call?

3) Use Find to extract a call with an ALERTING message.Can you see the CC message? If not, Why?


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1 1 36

Self-assessment on the Objectives

Please be reminded to fill in the formSelf-Assessment on the Objectives

for this module The form can be found in the first part

of this course documentation


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1 1 37

End of ModuleIntroduction


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Do not delete this graphic elements in here:

12All Rights Reserved Alcatel-Lucent 2008Module 2

Global Indicators3JK11044AAAAWBZZA Issue 01

Section 1GSM QoS Monitoring

EVOLIUM Base Station SubsystemIntroduction to Quality of Service and Traffic Load Monitoring - B10

3FL10491ADAAZZZZA Issue 01


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EVOLIUM Base Station Subsystem Introduction to Quality of Service and Traffic Load Monitoring - B10GSM QoS Monitoring Global Indicators

1 2 2

Blank Page


First editionLast name, first nameYYYY-MM-DD01

RemarksAuthorDateEdition

Document History


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1 2 3

Module Objectives

Upon completion of this module, you should be able to:

Explain what is a Global indicator and what are the main BSS indicatorsregarding GSM services provided by the Alcatel-Lucent BSS


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1 2 4

Module Objectives [cont.]



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1 2 5

Table of Contents

Switch to notes view! Page

1 Indicators Definition 7

2 Methodological Precautions 133 Typical Call Failures 204 Description of Global Indicators 835 Traps and Restrictions of Global Indicators 1046 Global Indicators Interpretation 111


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Switch to notes view! Page


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1 Indicators Definition


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BSS Indicators Definition (Alcatel-Lucent)

Global / Detailed

Numerical data providing information about network performance regarding: The complete network: GLOBAL indicator

An element of the network: DETAILED indicator TS/TRX/CELL/BTS/BSC/TC

A formulae of several counters

Counters vs. Indicators

Counters: provided by the BSS equipment

Indicators: computed by BSS Monitoring equipment

The indicators computation can be performed from several counters or by a simple counter mapping.

Example:

call drop rate = Call Drop nb / Call nb = f(counters)

call drop = Call drop nb = 1 counter


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Global Indicators

Measure the performance of the complete network

Analyzed according to their trend and values Usually every day (week, month)

Compared with:

Competitor results if available

Contractual requirements

Internal quality requirements


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Thresholds

EXAMPLE: Thresholds on Call Drop Rate indicator

Weekly CDR "GSM"

0,00%

0,50%

1,00%

1,50%

2,00%

2,50%

3,00%

3,50%

1 5 913

17

21

25

29

33

37

41

45

week number

CDR

weekly call drop rate

contractual call drop rate

quality CDR

Weekly CDR "GSM"

0,00%

0,50%1,00%

1,50%

2,00%

2,50%

3,00%

3,50%

1 5 913

17

21

25

29

33

37

41

45

week number

CDR

weekly call drop rate

contractual call drop rate

quality CDR

The Call Drop rate at network level has to compared to:

Contractual threshold: can be requested by the operator management to the operational radio team, can

be requested by the operator to the provider on swap or network installation

Quality threshold: fixed internally by radio team management.

Quality thresholds are usually tighter than contractual ones.


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Exercise

Are the indicators in the table below global ones?

INDICATOR DESCRIPTION G ?

average of call setup success rate for the network Yes

rate of call lost due to radio pb on cell CI=14, LAC=234 No

call drop rate in your capital

call drop rate of the cell covering a specific buidling

% of HO with the cause better cell (among other causes) for the network

average rate of TCH dropped for all TRX of the network carrying 1 SDCCH8

rate of SDCCH dropped on TRX1 of cell 12,24

call success of 1 PLMN

% of cells being congested today

INDICATOR DESCRIPTION G ?

average of call setup success rate for the network Yes

rate of call lost due to radio pb on cell CI=14, LAC=234 No

call drop rate in your capital

call drop rate of the cell covering a specific buidling

% of HO with the cause better cell (among other causes) for the network

average rate of TCH dropped for all TRX of the network carrying 1 SDCCH8

rate of SDCCH dropped on TRX1 of cell 12,24

call success of 1 PLMN

% of cells being congested today


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Typical KPI of Radio Network

Example of KPI used on network:

KPI Parameter Source

Call Drop Rate OMC/Drive test

Congestion Rate Drive test

Handover Success Rate OMC/Drive test

Busy Hour Traffic OMC

TCH Utilization OMC

Call Setup success rate OMC/Drive test

Coverage Drive test

Quality Drive test

The KPI is a good way to measure the overall performance of the network. Several KPI parameters will be

defined in the network to enable the operator to monitor the network performance throughout important

events, new release, soft/hardware upgrades, etc.

Normally the formula of KPI are defined by the operator, and usually different operators may consider

different KPIs and use different formulas. The KPI can be derived from driving tests and OMC traffic

statistics.


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2 Methodological Precautions


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Objective

Avoid typical errors regarding indicators interpretation


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Global Indicator Value

A good value for a global indicator

All network components are OK regarding this indicator

Example:

A global call drop rate of 1% can hide some cells with 10% of call drop rate


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Network Element Aggregation

The average value of an indicator for a Network:

Is not the average of cell results (or any sub-part of it)

BUT is the average weighted by the traffic

number of calls number of call drop call drop rate

cell 1 390 8 2,10%

cell 2 546 29 5,25%

cell 3 637 20 3,10%cell 4 1029 12 1,14%

cell 5 536 3 0,50%

cell 6 2 1 50,00%

cell 7 3 1 33,00%

cell 8 210 4 2,11%

cell 9 432 5 1,20%

cell 10 321 4 1,11%

average of cell results 9,95%

total nb of drop/total number of calls 2,10%


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Global Indicator Validity

To be reliable, an indicator must be based on a sufficient number ofevents

Estimation theory (MR.Spiegel, theory and problems of probability andstatistics , SCHAUM): if p is the probability of success for a complete population

if one is measuring the probability P based on a sample of size N

There is a probability of 95 % that p is between:P +/- 1.96*[(p*(1-p))/n]

Example: for p = 90 % and N = 100 => [ 84,12% ; 95,88% ]

This law cannot be used directly for indicators (an hourly indicator isnot based on a random sample), but it is giving a rough estimate of

level of confidence one can apply regarding the size of the sample If a sample (number of calls) is too small, one can take it for a longer

duration

On Alcatel-Lucent QoS monitoring tool (MPM application on OMC-R, NPA or RNO), NEs (BSS, Cell or TRX) are

highlighted with bad QoS indicator value if enough corresponding events have been observed (called

Validity threshold).

Examples:

Cells with bad Call Drop rate will be highlighted if CDR > CDR_threshold and if the Number of Calls is

greater than the CDR Validity threshold.

Cells with bad Outgoing handover success rate will be highlighted if OHOSUR > OHOSUR_threshold and if

the Number of Outgoing Handovers is greater than the OHO Validity threshold.


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Time Period Aggregation

Take care of data consolidation

Example:Mean cell congestion rate during busy hour:

Weighted average of cell congestion at the busy hour of the network?

Weighted average of cell congestion rate for its specific busy hour?

(definition of busy hour?)

Usually:

Cell Busy Hour = hour of the day where max TCH traffic (in erlang) is observed.

BSC Busy Hour = hour of the day where max TCH traffic (as the sum of the TCH traffic of all cells of the

BSS) is observed.


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Exercise

Is the conclusion given for each indicator right?

INDICATOR Sample

(calls)

conclusion OK ?

call drop = 0.9% in your country 2456435 all the cells have a good call dropNOK

call setup success for cell 15, 145 = 99.5% 2315 there is a good call setup success rate for

15, 145

In Paris: 2500 cells with 95% of call setup

successIn the rest of France: 5000 cells with

98%

3267872

for France

In France, call setup success = 97 %

call drop for BSS BSS_1 = 1% 4500 the call drop for BSS_1 is good

call drop for cell 156;13 = 5% 215 cell 156;13 has certainly a trouble

for BSS 1, call drop of 2.0%

for BSS 2, call drop of 3.0%

4000

2000

LA = BSS1 + BSS2 has a call drop of 2.3 %

MSC Stadium has a call setup success of

95 %

15346 BSS1 belonging to MSC Stadium has a call setup

success of 95%


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3 Typical Call Failures


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Objective

Description of the main call success and failures cases, with:

Main specific counters

Main protocol timers

Diagnose the main case of failures on A interface traces using the K1205emulation software


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Call Setup phasing

4 stages for a call establishment, 2 for alocation update:

1- Radio link establishment2- "SDCCH phase

then only for "Circuit Switch call"

3- TCH assignment

4- "Alerting/connection" phase

Each phase has a specific utility and someweaknesses

Radio Link EstablishmentSDCCH PhaseTCH assignmentAlerting/CNX Phase


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Radio Link Establishment - OC success

Originated Call: RLE success case

T3101: guard timer for SDCCH allocation (Default: 3 seconds)

CR/CC are used to exchange SCCP references

Any further message related to this call will have one (or 2) of these 2 references

K1205 can extract the call using these references (SLR, DLR!!)

MS BTS BSCMSC

CHANNEL REQUEST-------------(RACH)------------> CHANNEL REQUIRED

----------------------------------------------> MC8CCHANNEL ACTIVATION (SDCCH)

IMMEDIATE ASSIGN COMMAND

IMMEDIATE ASSIGN stop T3101

CC


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Radio Link Establishment - TC Success

Terminated Call: RLE success case

MS BTS BSC MSC

PAGINGPAGING COMMAND


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Radio Link Establishment - MO Success for DTM

Terminated Call: RLE success case

Radio Link EstablishmentSDCCH Phase

TCH assignment

Alerting/CNX Phase

MS BTS BSC MSC

CHANNEL REQUEST-------------(RACH) ------------> CHANNEL REQUIRED



IMMEDIATE ASSIGN


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Radio Link Establishment - Paging

RLE > Paging: MC8A=C8A

Normally all cells of the same Location Area must have the same MC8A counter value since all these cells

must be paged for an MT call on an MS located in the Location Area they are included in.

If not: it means that a cell is not declared in the right LA at NSS level.


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Radio Link Establishment - RACH Counter

RLE > RACH: MC8C=C8C

Caution: All Channels Required (therefore RACH) are counted in MC8C: valid and invalid causes (see later). Indeed ghostRACHs are also counted.

The Channel Required content corresponds to the Channel Request message sent by the MS to the BTS.

This Channel Request message is made up of one byte with 2 Information Elements (IEs):

8 7 6 5 4 3 2 1

+-----------------------------------------------+

ESTABLISHMENT RANDOM + - - - - - - - - + CAUSE REFERENCE +-----------------------------------------------+

ESTABLISHMENT CAUSE: This information field indicates the reason for requesting the establishment of a connection.This field has a variable length (from 3 bits up to 6 bits).

RANDOM REFERENCE: This is an unformatted field with a variable length (from 5 bits down to 2 bits).

Due to the fact that the NECI bit is always set to 1 in Alcatel-Lucent BSS, Establishment causes can be divided into 2

categories:

Valid causes: 5 (6 if GPRS)

000: Location Update (Normal, Periodic, IMSI Attach)100: Terminating call

101: Emergency call110: Call Re-establishment

111: Originating call (not emergency)011: if GPRS is implemented in the cell

Invalid causes: 3 (2 if GPRS)

001:010:

011: if GPRS is not implemented in the cell


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3 Typical Call Ffailures

Radio Link Establishment - OC Success Counters Split

RLE > success MO split: MC02x=C02x

MC02 =MC02A+MC02B+MC02C+.+MC02G+MC02H+MC02i

MC02A: LU

MC02B: SMS

MC02C: SS

MC02D: LU follow-on

MC02E: CR

MC02F: unknown

MC02G: IMSI Detach

MC02H: EC or NCMC02i: LCS

MC02A = Number of SDCCHs successfully seized for Normal or Periodic LU request (IMSI Attach also counted).

MC02B = Number of SDCCHs successfully seized for Short Message Service.

MC02C = Number of SDCCHs successfully seized for Supplementary Service.

MC02D = Number of SDCCHs successfully seized for LU with follow-on bit set to 1 (means that the SDCCH

phase will be followed by a TCH assignment for speech call establishment).

MC02E = Number of SDCCHs successfully seized for Call Re-establishment.

MC02F = Number of SDCCHs successfully seized in case of L3 Info (within 08.58 ESTABLISH INDICATION)

unknown by the BSC but transferred to the MSC.

MC02G = Number of SDCCHs successfully seized for IMSI Detach.

MC02H = Number of SDCCHs successfully seized for Normal or Emergency call.MC02i = Number of Mobile Originating SDCCH establishments for LCS purposes.

Also, Evaluation of the Mobiles location (see the next slides)

LCS: Location Services


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Radio Link Establishment - SDCCH Congestion Failure

Main failure cases for Radio Link Establishment Radio Link EstablishmentSDCCH Phase

TCH assignment

Alerting/CNX Phase

SDCCH

Access Failure

SDCCH

Congestion

SDCCHCongestion

SDCCH

Radio Failure

SDCCH

Radio Failure

SDCCH

BSS Problem

SDCCH

BSS Problem


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Radio Link Establishment - SDCCH Congestion

RLE > SDCCH congestion

The Immediate Assignment Reject mechanism can be disabled at OMC-Rlevel

It is not activated for answer to paging

If disabled, no answer to the MS

The MS will repeat automatically its request in case of congestion (nextslides)

Waiting for T3122 expiry in case of Immediate Assignment Reject

Waiting for T3120 expiry otherwise

MS BTS BSCMSC


----------------------------------------------> MC8CNo free SDCCH !!MC04



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Radio Link Establishment - SDCCH Congestion Counter

RLE > SDCCH congestion: MC04=C04


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Radio Link Establishment - SDCCH Cong. Consequences

RLE > SDCCH congestion: MAIN CONSEQUENCES

The MS will try "max_retrans +1 " times before giving up Immediately for phase 1 MS

After T3126 for phase 2 MS (still waiting for Immediate Assignment during this timer)

In case of "max_retrans+1" failures, the MS will: Either try an automatic cell reselection

Or do nothing

In case of LU, the MS will attempt a new LU request

In case of Call establishment, the MS will not re-attempt automatically. It is up to thesubscriber to try to set up the call again


TCH assignment

Alerting/CNX Phase


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Radio Link Establishment - SDCCH Cong. Causes/Solutions

RLE > SDCCH congestion: MAIN causes/solutions

Location area border results in excessive location update and SDCCHattempt Inadequate LA design (too many LUs) Modify CRH (Cell Reselect Hysteresis)

Modify BSC period location update Solve frequent handover problem between dual-band network

Excessive short messages Add SDCCH channel

Enable dynamic SDCCH Dynamic Allocation function

Insufficient system capacity, lack of SDCCH channels Expansion for more TCH and SDCCH channels More SDCCHs should be added

Improper configuration of system parameters, RACH system parameter Increase RACH access threshold (overcoming interference) with care!


TCH assignmentAlerting/CNX Phase

SDCCH congestion can be too high because of the subscribers' traffic demand in terms of calls / LUs.

Solution = add a TRX or site / redesign the LA plan

High SDCCH congestion can be observed at peculiar period of the day due to a peak of LU requests

generated by a big group of subscribers entering a new LA at the same time (bus, train, plane).

Solution = redesign the LA plan or play on radio parameters (CELL_RESELECT_HYSTERESIS, WI_OP)

High SDCCH congestion can be abnormally observed without real MS traffic in case a high level of noise or

the proximity of a non-GSM radio transmitter.

Solution = change the BCCH frequency or put an RX filter

High SDCCH congestion can also be abnormally observed in a cell in case one of its neighboring cell is

barred.

Solution = Remove the barring


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Radio Link Establishment - SDCCH Cong. Causes/Solutions [cont.]

RLE > SDCCH congestion: MAIN causes/solutions

Board (TRX) fault and transmission fault result in SDCCH congestion

"Common Transport Effect"

Difficult to avoid for small cells

Abnormal SDCCH traffic

Phantom" channel requests (seen in SDCCH RF failure session)

Neighboring cell barred


TCH assignment

Alerting/CNX Phase

SDCCH congestion can be too high because of the subscribers' traffic demand in terms of calls / LUs.

Solution = add a TRX or site / redesign the LA plan

High SDCCH congestion can be observed at peculiar period of the day due to a peak of LU requests

generated by a big group of subscribers entering a new LA at the same time (bus, train, plane).

Solution = redesign the LA plan or play on radio parameters (CELL_RESELECT_HYSTERESIS, WI_OP)

High SDCCH congestion can be abnormally observed without real MS traffic in case a high level of noise or

the proximity of a non-GSM radio transmitter.

Solution = change the BCCH frequency or put an RX filter

High SDCCH congestion can also be abnormally observed in a cell in case one of its neighboring cell is

barred.

Solution = Remove the barring


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Radio Link Establishment - SDCCH Cong. Resolution?

RLE > SDCCH congestion

DYNAMIC SDCCH ALLOCATION

CHANNEL REQUEST

CHANNEL REQUIRED

MS BTS BSC

(RACH)

If No free SDCCH, then

run dynamic SDCCH/8timeslot allocation

algorithm. If allocation is successful, then

activate dynamic SDCCHsub-

channeland serve request

If allocation was unsuccessful, then reject SDCCH request (possibly

using the Immediate Assignment Reject procedure).

MC801a&b

MC802a&b


TCH assignment

Alerting/CNX Phase

SPECIFIC COUNTERS (Type 110 / Cell Level):

MC800 Average number ofavailable dynamic SDCCH/8 timeslots.

MC801a Average number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR).

MC801b Maximum number of busy dynamic SDCCH/8 timeslots allocated as TCH (FR or HR).

MC802a Average number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots.

MC802b Maximum number of busy SDCCH sub-channels allocated on the dynamic SDCCH/8 timeslots.These four previous counters are Inspection Counters; that means that the resource is checked regulary by the BSC and at the

end of the period, an average is done. Example: 3 physical channels are defined as Dyn SDCCH and the counter gives the following

indication:

MC801a = 1.7 that means sometimes the 3 Dyn SD are allocated as TCH, sometimes only 2 of them, sometimes 1 or 0 and the

average is 1.7.

The FOLLOWING COUNTERS ARE IMPACTED BY the Dynamic SDCCH Allocation feature: MC28, MC29 The Number of busy radio timeslots in TCH usage takes into account the busy TCH timeslots and the dynamicSDCCH/8 timeslots allocated as TCH.

C30, MC31 The Number of busy SDCCH sub-channels takes into account the SDCCH sub-channels allocated on the static anddynamic SDCCH/8 timeslots.

C370a, MC370a, C370b, MC370b The Number of times the radio timeslots are allocated for TCH usage (FR / HR) takes intoaccount the busy TCH timeslots and the dynamic SDCCH/8 timeslots allocated as TCH.

C/MC380a/b C/MC381a/b The Cumulated time (in second) the radio timeslots are allocated for TCH usage (FR or HR) does nottake care whether the TCHs are allocated on the TCH radio timeslot or on the dynamic SDCCH/8 timeslots.

C39, MC390, C40, MC400 The Number of times or the Cumulated time (in second) the SDCCH sub-channels are busy does nottake care whether the SDCCH sub-channels are allocated on the static or dynamic SDCCH/x timeslot.

C/MC34 C/MC380 The Cumulated time (in second) all TCHs / SDCCHs in the cell are busy does not take care whether the TCHs /SDCCHs are allocated on the TCH radio timeslot /SDCCH/x timeslot or on the dynamic SDCCH/8 timeslots.

C/MC320a/b/c/d/e Free TCH radio timeslots count the free TCH timeslots and the free dynamic SDCCH/8 timeslots.


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Radio Link Establishment - SDCCH Radio Failure

Main failure cases for Radio Link Establishment

SDCCH

Access Failure

SDCCH

Congestion

SDCCH

Congestion

SDCCHRadio Failure

SDCCHRadio Failure

SDCCH

BSS Problem

SDCCH

BSS Problem


TCH assignment

Alerting/CNX Phase


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Radio Link Establishment - SDCCH Radio Access Failure

RLE > SDCCH RF Failure

MS BTS BSC MSC




IMMEDIATE ASSIGN


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Radio Link Establishment - Real Radio Problems

RLE > SDCCH RF Failure

Main causes > real radio problems

Unbalanced cell power budget

Bad coverage (for example a moving car)

Interference (for example downlink)

In case of radio failure, the MS will retry as for SDCCH congestion


TCH assignment

Alerting/CNX Phase

Unbalanced Power Budget:

Bad coverage:

Interference:

DL interference area

AGCH lost

RACH

building

BTS

Channel Request

Access Grant

Max Path Loss UL

Max Path Loss DL

AGCH

RACH


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Radio Link Establishment - Ghost RACH

intro to quality of service & traffic load monitoring b10.pdf

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