9C. GSM - Roaming and Switching

7/28/2019 9C. GSM - Roaming and Switching

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ROAMING ANDSWITCHING

Mobile Application Part (MAP)

Interface

Key thing in GSM is that subscribers can be called

globally. This is because of roaming or mobility functions

These rely mostly on GSM extensions of SS#7

Mobile Application Part procedures relevant to roaming

are: Location Registration/update, IMSI Attach/Detach,requesting subscriber data for call se-up, and paging.

Additionally in MAP: functions for supplementary

services and handover, subscriber management, IMEI

management, authentication/identification management,

data transfer for SMS

Mobile Application Part (MAP)

Interface

MAP entities for roaming services are in MSC,

HLR and VLR.

At subscriber interface MAP functions

correspond to functions of Mobility management(MM)

Most important functions Location registration

and location update –enables to route the calls

where the subscriber is

Overview of Location

Registration

Before mobile user can get GSM services the MS has t be

registered to the network

Registration can happen in Home Network (Home PLMN) or to a

visited network provided there is roaming agreement between the

network operators

New registration needed when user changes network and a TMSI

has not been issued yet. In this case the user has to report to the

network using IMSI and receives TMSI when doing location

registration

The registration data is stored to the SIM card. So after power up

only location update is needed if uses stays within same network A5 = encryption algorithm in air interface, TMSI is transmission is

encrypted

Overview of Location

Registration

Location Update

MS already has TMSI in the current network.

This and LAI identify the user. User also has

encryption key Kc.

After authentication new TMSI is generated, andit is transmitted in encrypted form (Kc).

After the process the new: 3-tuple RAND,

SRES, Kc also called SIM-Triplet are updated to

VLR and consumed old ones are deleted. Authentication center usually has pre-calculated

triplets available to make process faster.

Location Update

Location Update After

Changing VLR Area

In this case user changes to a new VLR area,

and in location update the new VLR has to ask

registration parameters (IMSI, RAND, SRES,

Kc) from old VLR. In case user data (TMSI etc.) is lost from

database, the authentication needs to be done

by using IMSI.

After that a new TMSI is assigned and it is nowtransferred in encrypted form.

Location Update After

Changing VLR Area

Routing Call to MS

Due to mobility users cannot be called directly.

In location update The MS obtains temporary

routing number MSRN according to which MS is

reachable. In case of incoming call from outside the MS is

dialed by MSISDN. Call is routed to Gateway

switch GMSC based by MSISDN. GMSC

interrogates the MSRN from HLR. GMSC routes

the call using MSRN. MSC then searches

corresponding TMSI from VLR and routes the

call to destination

Routing Call to MS

Call Routing Variants for

National MSISDN

Call Routing Variants for

International MSISDN

Routing Through GSMC for

International MSISDN

Outgoing Call Setup

Interrogating of Routing

Information for Incoming Call

Incoming Call Setup

Mobile Initiated Call

Termination

Forwarding Short Message

In the air interface a connectionless protocol

(Short Message Transfer Protocol, SM-TP) used

for transfer short messages

Short messages are transferred using signalingchannels (SACCH or SDCCH). Messages are

stored in Short Message Center (SMS-SC) and

delivered by store and forwarded basis

(transmission when receiver available)

Incoming message

Arrives from Short message Center SMS-SC to a Short Message

Gateway MSC (SMS-GMSC). Location MS need to be

determined, then authentication etc.

MAP procedures used for transfer. Success / failure reported to

SMS-GMSC (MAP message Forward Acknowledgement / Error

Indication). GMSC then informs SMS-SC.

Outgoing message

SMS from MS is straightforward sins SMS-GMSC is know to all

MSC, os message can be immediately passed to SMS-GMSC

Handover

Handover is the process where the connection is

set to a new base station as signal goes too low.

This ensures continuous communication despite

of user movement.

Several possibilities depending on location at

the network.

Controlled by protocols and algorithms based on

measurement data.

Handover

Internal and External

Handover

Signaling for Intra MSC

Handover

Handover Decision

Handover Causes and

Threshold

Handover is based on measurements. When

predefined limits are exceeded handover is

commanded.

Limits can be fine-tuned by operator to optimizenetwork

Handover Causes and

Threshold

Handover Causes and

Threshold

Detection of Mandatory

Handover

Typical situations for a mandatory handover

The received signal level in the uplink or downlink

(RXLEVEL_UP / RXLEVEL_DL) drops below the respective

handover threshold value (L_RXLEVEL_UP_H /

L_RXLEVEL_DL_H) and power control range has been

exhausted, i.e. MS or BSS have reached their maximaltransmitted power

The bit error rate ratio as a measure of signal quality in uplink

and/or downlink (RXQUAL_UP / RXQUAL_DL) exceeds the

respective handover threshold value (L_RXQUAL_UP_H /

L_RXQUAL_DL_H) while at the same time the received signal

level drops into the neighbourhood of threshold value

The maximum distance to the base station (MAX_MS_RANGE)

has been reach

Detection of Mandatory

Handover

Basic Handover Between Two

Subsequent Handover

(Handback) MSC-A MSC-B

Subsequent Handover MSC-B

MSC-B’

9C. GSM - Roaming and Switching

Documents

GSM Association Roaming Database, Structure and Updating

PART - A Vtusolutionvtusolution.in/uploads/9/9/9/3/99939970/wireless_communication... · GSM and TDMA techniques, ... GSM system operation, Traffic cases, Cal handoff, Roaming, GSM

International Roaming for GSM - National Tsing Hua Universitywmnet.cs.nthu.edu.tw/.../International_roaming_for_gsm.pdf · 2013-05-23 · 4 Introduction GSM supports roaming services

GSM Association Roaming Database, Structure and Updating

Roaming Database, Structure and Updating Procedures 7.4 · PDF file4 GSM Associations Official Document: IR.21

Multi-user operation and roaming over wide area networks · Product Evolution Future personal ... BTS GSM Pico-cell PSTN Internet Roaming Gateway BTS Controller WLAN Access ... •

Discussion Paper - DotEcon · International roaming– the ability to use one’s mobile phone on foreign ... is a widely shared view that the roaming capabilities available to GSM

DELIVERING PROFITABLE GSM/3G ACCESS TO UNDERSERVED … · GSM/3G management systems and facilitates roaming and MNO inter-working. DELIVERING PROFITABLE GSM/3G ACCESS TO UNDERSERVED

Roaming Configuration For Huawei - congodouane.orgcongodouane.org/sites/default/files/2019-06/Huawei - Roaming Audit - v4.pdfOutbound GSM SCCPGT, VSLIST HLR,PGW Outbound GPRS SCCPGT,

Etisalat International Roaming Partners List · Etisalat International Roaming Partners List ©2017 Etisalat.ae Page 1 of 17 No Country Operator Zone GSM Postpaid WASEL Direct CAMEL*

Organisation of GSM International Roaming Tests

Roaming Hubs for CDMA: Rapid Roaming Expansion Made Possiblecdg.org/resources/files/white_papers/CDMA Roaming Hub... · 2017-12-08 · 5 Learning from GSM Roaming Experiences GSM

GSM roaming brokerage allows integration of Carribean’s fragmented mobile markets

LBS Roaming and Inter working Guidelines 12 February 2010 · 2015-02-05 · GSM Association Non-confidential Official Document IR.63 - LBS Roaming and Inter-working Guidelines V3.0.0

ROAMING : THE POTENTIAL IMPACT OF A … submission - attachment 1... · dependent on the figures published by the GSM Association, which is itself an ... roaming shows, however, that

GSM 900 GSM 1800 GSM 1900 Roaming …GSM Association Non-confidential Official Document IR.30 - GSM 900 GSM 1800 GSM 1900 Roaming Interoperability V3.0.0 Page 3 of 16 1 Introduction

International Roaming for Gsm New

Roaming Details document - techsixtyfour.com International... · Chad Airtel Chad GSM 900 6 Chad MILLICOM TCHAD GSM 900 6 Chad Thuraya (sattelite) SAT Chile Claro GSM 1900 6 Chile

KTF Interstand KTF InterstandInterstandInterstand Roaming ...cdg.org/.../events/CDMASeminar/031211/16-KTF_CGR_Panel_Present… · - Service : ‘GSM/CDMA Automatic Roaming Service’

GSM roaming