1Astellia confidential

www.astellia.com

Cigale GSM basics

2Astellia confidential

At the end of the lesson the student will be able to:

Describe the GSM architecture Define the technical characteristics of Cigale Understand the Interests of Cigale Understand the usage of the different tools Describe the A-Interface protocol Understand the different Basic call flow

ObjectivesObjectives

3Astellia confidential

GSM Architecture

GSM OverviewGSM Overview

4Astellia confidential

Post processing software of GSM A interface capture frames:

Works under PC windows

Manages several types of capture platforms

Processing on specific time ranges and by time intervals

Processes Gigabytes of data

Technical Technical charactericticscharacterictics

5Astellia confidential

Measure and help for QoS improvement:

Detection of shortcomings : radio, BSS, NSS, transmission (PCM, CICs, transcoders)

Generation of both user and system oriented indicators

Investigation of user or network problems

Optimization (radio) and dimensioning

Information for marketing

InterestsInterests

6Astellia confidential

Statistics: Complementary to those of OMCs and manufacturer tools, more

accurate Manufacturer independent

Investigations: Better approach (more global) than a simple protocol analyzer Possibility of quickly isolating specific groups of users who

encounter problems (roamers, data calls, ) Troubleshooting with Activity Analysis

InterestsInterests

7Astellia confidential

Shortcomings detection: Allocation issues (looped PCM, CIC Pb) Traffic less cells (blocked TS) Handover failures (by cells couples), bad neighbourhood

declarations, parameter settings Radio drops (interferences) Saturations (radio, network, queuing) Paging efficiency Roaming (location updates failures) SMS efficiency (statistics per SMS Center)

InterestsInterests

8Astellia confidential

Examples

QoS indicators SDCCH failures, assignment failures, TCH drops Call setup efficiency, established calls drops Inter BSC handover successes Location update success rates SMS sending and reception success rates

Investigation ExamplesInvestigation Examples

9Astellia confidential

Investigation with Cigale view High call drop rates Handovers inefficiency, ping-pong handovers Location update rejects

Deeper investigation with Activity Analysis Too long call setup durations (according to the called numbers) Data calls discrimination Location update rejects (per IMSI) Calls traces per identities (IMSI, IMEI, numbers)

Investigation ExamplesInvestigation Examples

10

Astellia confidential

Software architectureSoftware architecture

SQL

Txt files

XL3 files

Cigale GSM

Cigale Roaming

Activity Analysis

Cigale View

Roaming View

SLM

Cigale Trace Activity AnalysisRoaming AnalysisTrace AnalysisSLM Analysis

Trending & aggregation

11

Astellia confidential

Processing & Viewers

SotwareSotware architecturearchitecture

12

Astellia confidential

Cigale Engine

Processing & viewersProcessing & viewers

13

Astellia confidential

Cigale View

Processing & viewersProcessing & viewers

14

Astellia confidential

Activity Analysis

Processing & viewersProcessing & viewers

15

Astellia confidential

Way to use the ToolsDetections of lack of QoS, thanks to statistics

Detailed causes

Calls impacted by a specific cause

Flow chartAvailable in V5.5

Protocol decoding

Statistic(View)

Troubleshooting(Activity Analysis)

Processing & viewersProcessing & viewers

16

Astellia confidential

Characteristics of the main layers Several protocol layers manage the messages exchange between the

mobile terminal and the network

SCCP: connection management between MSC and BSC for every MS

BSSAP: divided in two parts- BSSMAP: procedures between BSC and MSC related to a MS

(HO execution for example)- DTAP: messages directly exchange between the MS and the MSC

MM, CM: Mobility & Connection Management- MM include message related to the mobility and the security- CM include call treatment (CC), supplementary services (SS) and short messages

services (SMS)

A interface protocolsA interface protocols

17

Astellia confidential

MTP1

MTP2

MTP3

SCCP

MTP1

MTP2

MTP3

SCCP

A interface protocolsA interface protocols

Ph. Layer

LAPDm

RR

MM

CM

Ph. Layer

LAPD

RR

(+BTSM)

DTAP BSSMAP

BSSAP

distribution function

DTAP BSSMAP

MM

CM

BSSAP

distribution function

Direct dialogue between peer entities

Air Interface

AbisInterface

MS BSC MSC

18

Astellia confidential

Ph LayerIP

SCTPM2UAMTP3B

M3UA

SCCP

Ph LayerIP

SCTPM2UA

MTP3BM3UA

MTP1MTP1

MTP2 MTP2

MTP3

SCCP

A interface A interface protocolsprotocolsNGN ArchitectureNGN Architecture

Ph. Layer

LAPDm

RR

MM

CM

Ph. Layer

LAPD

RR

(+BTSM)

DTAP BSSMAP

BSSAP

distribution function

Direct dialogue between peer entities

Air Interface

AbisInterface

MS BSC

DTAP BSSMAP

MM

CM

BSSAP

distribution function

MSSMGW (SGW)

MTP3

19

Astellia confidential

Description of the SCCP messages

SCCP connection establishment- Request : Connection Request, CR- response OK : Connection Confirm, CC- Refusal : Connection Refused, CREF

Sending of messages : Data Form 1, DT1

Release of an SCCP connection- request : Released, RLSD- confirmation : Release Complete, RLC

A interface protocolsA interface protocols

20

Astellia confidential

BSS MSCCR [ CL3I [ LUREQ ] ]Connection Request [ Complete Layer 3 Information [ Location Updating Request ] ]

CCConnection Confirm

BSS MSCCR [ HOREQ ]Connection Request [ Handover Request ]

CC [ HORAC [ HOCMD_RR ] ]Connection Confirm [ Handover Request Acknowledge [ Handover Command (RR) ] ]

Details of proceduresDetails of procedures

Location Update:

Incoming Handover driven by the MSC

21

Astellia confidential

CHANNEL REQUESTIMMEDIATE ASSIGNMENT Establishment of a RR

connection

ALERTING Call confirmation

CONNECT ACK Call startedCONNECT

ASSIGNMENT CMDASSIGNMENT CMP Allocation of a traffics channel

MSGSM NETWORK RTCP or RNIS

CM SERVICE REQUEST Service Indication

AUTHENTICATION REQUESTAUTHENTICATION RESPONSE Authentication

CIPHERING MODE CMDCIPHERING MODE COMPLETE Ciphering mode

SET UPCALL PROCESSING Call routing

Details of Originating CallDetails of Originating Call

Originating call

22

Astellia confidential

PAGING REQUEST

ALERTING Call confirmation

CONNECT ACKCall startedCONNECT

ASSIGNMENT CMDASSIGNMENT CMP Allocation of a traffics channel

MSGSM NETWORK RTCP or RNIS

AUTHENTICATION REQUESTAUTHENTICATION RESPONSE Authentication

CIPHERING MODE CMDCIPHERING MODE COMPLETE Ciphering mode

SET UPCALL CONFIRMED Call routing

CHANNEL REQUEST

IMMEDIATE ASSIGNMENT

Establishment of a RR connection

Service Indication PAGING RESPONSE

Details of Terminating Details of Terminating CallCall

Terminating call

23

Astellia confidential

CHANNEL REQUESTIMMEDIATE ASSIGNMENT Establishment of a RR

connection

LOCATION UPDATING ACCEPT

CHANNEL RELEASE

TMSI REALLOCATION CMD

Allocation of a temporary identity

MSGSM NETWORK RTCP or RNIS

MM LU REQUEST Service Indication

AUTHENTICATION REQUESTAUTHENTICATION RESPONSE Authentication

CIPHERING MODE CMDCIPHERING MODE COMPLETE Ciphering mode

TMSI REALLOCATION CMP

LU accepted

Radio resource released

Details of Location Update Details of Location Update procedureprocedure

Location Update

TMSI reallocation only for the first location update and for location update between VLR