CORE PLANNING ANG ENGINEERING.pdf

8/11/2019 CORE PLANNING ANG ENGINEERING.pdf

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NSD - CORE Planning & Engineering

GSM SYSTRA

(NSS)




GSM SUBSYSTEM ARCHITECTURE




Network Switching Subsystem Components


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AC VLR BTS Air Interface ME SIM

A3

A8 A8 A5 A5

A3 Authentication

EIR MEIMEI Checking

Ciphering

COMPARING

RAND

KiSRES SRES

A3 A3

A8Kc Kc

Traffic Traffic

TDMA FNTDMA FN

A8 A5 A5

Request of IMEI

Provide IMEI

Encrypted DataEncrypted Data

GSM SECURITY MANAGEMENT

Ki




CALL SET-UP IN A GSM NETWORK

MSISDN = CC +NDC +SN

CC = Country CodeNDC = National Destination Code

SN = Subscriber #

IMSI = MCC + MNC + MSIN ( fixed 15 digits )

MCC = Mobile Country CodeMNC = Mobile Network CodeMSIN = Mobile Subscriber Identification #

LAI = MCC + MNC + LAC

MCC = Mobile Country Code (of visiting country)MNC = Mobile Network Code(of serving PLMN)LAC = Location Area Code




CALL ESTABLISHMENT (Mobile Originating–Mobile Terminating)

PSTNBTS

1

BTS2BSC

2

BSC

1

MSC

VLR1

MSC

VLR2

HLR

HLREnquiry

VLR DBIMSI MSRN LAI

Services2

Speech

LAI 1

LAI2

MSRN

MS

MSB

IMSI

B

C

MSISDN

MSISDN (C)

CC+ NDC + SN1 2142345678

IMSI = MCC+MNC+MSIN

MSRN = CC+NDC+SN

MSISDN

HLR DBMSISDN IMSI VLR Address Sub.Data1+972+7452856 310+02+1234567890 xyzservices58+2+1234567 xxx + xx + xxxxxxxxxx abcservices:




PSTNBTS

1BSC

1

MSC

VLR1

MSC

VLR2

HLR

HLREnquiry

HLR DBMSISDN IMSI VLR Address Sub.Data1+214+1234567 310+02+1234567890 xyzservices58+2+1234567 xxx + xx + xxxxxxxxxx abcservices:

VLR DBIMSI MSRN LAI

DATA310+02+1234567890 1

services

LAI 1

MSRNPOOL

MSB

IMSI

A

B

MSISDN

MSISDN (B)CC+ NDC + SN1 214

1234567

IMSI = MCC+MNC+MSIN

MSRN = CC+NDC+SN

MSISDN

CALL ESTABLISHMENT (PSTN Originating–Mobile Terminating)




CALL ESTABLISHMENT (Mobile Originating – PSTN Terminating)

PSTNBTS

1BSC

1

MSC

VLR1

MSC

VLR2

MS

LAI 1

B

MSISDN

MSISDN (A)CC+ NDC + SN1 9723456789

HLR

A




SMS FLOW

MO SMS PROCEDURE




MO – SMS PROCEDURE

MS-AMSC/VLR SMSCBTS / BSC

The MS sends an SM through SDCCH (if the MS is idle) or

SACCH (if the MS is busy) signaling channel on the radio interface.

The VMSC checks the data of subscriber A from the VLR.

The VMSC routes the SM to the SMSC

The SMSC sends delivery report to the VMSC

The VMSC sends a report to the MS of subscriber A through SDCCH or SACCH

The report is a delivery or a failure report, depending on whether

the sending was successful or not.

MT SMS PROCEDURE




MT – SMS PROCEDURE

GMSC/VLR HLRSMSC MSC/VLR MS-B

SMSC sends SRI (Send Routing Info) to HLR

HLR provides VMSC address of B subscriber

SMSC routes SMS to VMSC

The VMSC asks the VLR for the status and

location area of the MS of subscriber B .

BTS / BSC

If the MS is in idle mode, the VMSC starts paging and delivers

the SM to it through the SDCCH of the BTS where the MS is

located. If the MS is in busy mode, the VMSC sends the SM

through the SACCH .

MS sends delivery report to VMSC

The VMSC sends a report to the SMSC.

The report is a delivery or a failure report

SMP/SMSC sends delivery status to HLR for

the MNRF / MWD uodate

UNSUCCESSFUL MO SMS DELIVERY




UNSUCCESSFUL MO – SMS DELIVERY

The sending of the MO-SM can fail in any of the below situations:

Teleservice Not Provisioned - Subscriber A does not have the T22 (MO-SMS) subscription

Operator-determined barring is activated by the network operator or barringsupplementary service is activated by the subscriber

UnknownSC - SMSC address and A number prevention is defined. Short message service

center in unknown.

Facility Not Supported - The MO-SM facility is not supported in the network Invalid SME Address - The short message transfer is rejected because the SME address is

invalid

Unidentified Subscriber - Subscriber A is not the subscriber of the relevant SMSC

SC Congestion - There is congestion in the SMSC System failure - SystemFailure on the MAP interface and MSC-SMSC interface

UNSUCCESSFUL MT SMS DELIVERY




The delivery of the MT-SM can fail if any of the following conditions are applicable:

Absent Subscriber - Subscriber B is absent. As a result, MWD (including the SMSC address)and the MNRF flag are set in the HLR. The following error codes are considered as absent subs

in MAP V2Reason code Network element setting the reason code

No paging response through the MSC VLR

IMSI detached VLRRoaming restriction HLR

MS purged HLR

Unidentified subscriber through the MSC VMSC

Unidentified Subscriber - The subscriber is unknown in the VLR. As a result, (including the

SMSC address) the MNRF flag is set in the HLR.

Unknown Subscriber - The subscriber is unknown in the HLR. In this case, the MWI is not

set. If the global title analysis fails in the GMSC towards the HLR, the SMSC receives the

Unknown_Subscriber error code from the GMSC. This error code is a permanent error code, andthe SMP/SMSC ceases to retry the sending of the SM.

MS Busy for MT SMS - The message is rejected because of congestion encountered at the

visited MSC.

Busy Subscriber - An SMSC is trying to send an SM to the subscriber while another SMSC is

already sending him SMs (the paging request is rejected )

UNSUCCESSFUL MT – SMS DELIVERY

UNSUCCESSFUL MT SMS DELIVERY




MNRF flag is set in the HLR, but the priority flag is not set. The corresponding error code is

transferred on the MSC-SMSC interface.

Call Barred - Information is found in the HLR that incoming call barring applies to subscriber

B

Memory Capacity Exceeded - A positive response is received for paging, but the memory

capacity of the MS is exceeded (the MCEF flag was not set in the HLR). As a result, MWD

(including the SMSC address) and the MCEF flag are set in the HLR.

Facility Not Supported - SMSC address is barred for the visitor subscribers

Illegal Subscriber - SMSC address is barred for home subscribers

System Failure - System failure occurs

MT Congestion – Unavailability of resources during the MT-SMS delivery

Network / Protocol Failure – Unknown LAC, paging error, system failure and protocol failure

such as non-response from channel release

No Report From the Network – Network time-out reached while waiting for response /

acknowledgement

UNSUCCESSFUL MT – SMS DELIVERY

REPORTSM DELIVERY REPORT




REPORTSM – DELIVERY REPORT

1. SMP sends SRI request to HLR and HLR provides

the SRI Response

2. SMP forwards SM to VMSC and VMSC sends an

error notification to SMP

3. SMS-GMSC informs the HLR if an absentsubscriber, unidentified subscriber, or SM

delivery failure with 'error cause MS memory

capacity exceeded' indication is received from

the visited MSC

4. HLR invokes an alert SC procedure to the

corresponding SMSC/SMP after location update

of MS-B

NOTE:

If subscribers are temporarily out of coverage, and a short message is sent to them, an MNRF is

set in the VLR. The service centre address is set in the subscriber's message waiting data(MWD) list. When the MS goes back to coverage area, the VLR does not recognize any change,

so the MNRF is not checked until a call or a periodic location update is made. This situation

causes delay in the SM delivery.




GPRS(General Packet Radio Services)

Planning & Engineering - CORE

GPRS OVERVIEW




GPRS OVERVIEW

• GPRS is basically a service introduced to the existingGSM network which permits mobile data transmission

using packet switching techniques.

• GPRS is basically a service introduced to the existingGSM network which permits mobile data transmission

using packet switching techniques.

DATA APPLICATIONS SUPPORTED

• WAP / Internet

• Multimedia Messaging Service• E-mail• other data supported applications

GPRS OVERVIEW




GPRS OVERVIEW

EVOLUTION TO 3G

Circuit Data

Speech

HSCSD

GPRS171.2 kbps

EDGE384 kbps

3G2 Mbps

Pre 1997 1997 1998 1999 2000 2001 2002

Functionalityand

Capabilities

GPRS OVERVIEW




GPRS OVERVIEW

GSM NETWORK

MS

BTS

BSCMSC

GPRS NETWORK

INTERNET

SGSN

GGSN

FW

• This is a technology that

introduce new networkequipments for dataapplication such as internet.

• This is a technology that

introduce new networkequipments for dataapplication such as internet.

CIRCUIT SWITCH VS PACKET SWITCH




C CU S C S C S C

PSTN

GPRSBackboneIP Network

Internet

Circuit Switched

GPRS Core

BSC

MSC

GGSN

SGSN

BTS

Packet Switching

Circui t Switching

Packet Switched

GPRS NETWORK




Border Gateway(BG)

GGSN

ChargingGateway (CG) Internet

Backbonenetwork

(IP based)

Intranet

Fire Wall(FW)

LIG

SGSN

Inter-PLMNnetwork Domain Name Server

(DNS)

HLR/AuCEIR/SMSC

PSTNNetworkMSC/VLR

IubBTS

BTS

BTS

BSC

BSC

GPRS NETWORK




SGSN (Serving GPRS Support Node)

• Mobility management• Authentication (PAPU/SMMU)• Ciphering & compression (PAPU)• Protocol conversion

• GTP tunneling to GGSN• Interaction with HLR, MSC/VLR • Charging & statistics• NMS interfaces

GPRS NETWORK




SGSN Sub-units:

PACKET PROCESSING UNIT (PAPU)

– Protocol conversion from Gn to Gb interfaces

– 15,000 connected subscriber

– Collects CDR’s and sends to MCHU for transmission to CG

SIGNALLING AND MOBILITY MANAGEMENT UNIT

(SMMU)

Signaling – Provides CCS7 interfaces to NSS network elements (max 24).

– Handles MTP, SCCP, TCAP, BSSAP+ and MAP protocols.

– SMS forwarding.

Mobili ty management – Visiting GPRS subscriber database can handle a maximum

of 60,000 subscribers.

– IMSI/GPRS attach detach, LA/RA updates, paging,

authentication, etc.

– Storage of 10 triplets per attached subscriber.

GPRS NETWORK




GGSN (Gateway GPRS Support Node)

• Essentially a router

• Interfaces to external IP networks• GTP tunneling to SGSN

• Charging & statistics• NMS interfaces

BG (Border Gateway)

• Essentially a router similar to GGSN

• Provides a secure 'tunnel' for

transferring data on the inter-PLMNbackbone between different operators

• Supports protocols like BGP-4

GPRS NETWORK




DNS (Domain Name Server)

• Standard IP device

• Converts domain names into IP addresses• Based on a hierarchical & distributed

model

FW (FIREWALL)


• Protects against unauthorized access (hackers)

GPRS NETWORK




DNS (Domain Name Server)


• Converts domain names into IP addresses• Based on a hierarchical & distributed

model

FW (FIREWALL)


• Protects against unauthorized access (hackers)

GPRS NETWORK




CG (Charging Gateway)

• Collects charging data from SGSN & GGSN

• Processes the charging data & forwards it to the Billing System

Ethernet Catalyst Switch

• Connects all the Backbone elements

• Separates different segments of traffic by providing VLAN configuration

GPRS CONNECTION PROCEDURE




• GPRS Mobility Management (GMM) - Connection to GPRS network

Procedures that take care of the mobility of the user such as GPRS attach, updates about

the location of the mobile & security. The GMM procedures are similar to the mobilitymanagement procedures for circuit switched users.

• Session Management (SM) - Connection to IP network

Procedures that handle the GPRS MS connection management to external datanetworks. The process of assigning an IP address for becoming part of the IP-network isknown as PDP context activation. An MM context must be established between the MS &the SGSN before any SM activities are possible.

GPRS MOBILITY MANAGEMENT STATE




• Idle State – Subscriber is not attached to the GPRS network

– No valid MM context of the subscriber e.g. MS switched off

• Ready State

– After successful GPRS Attach

– Location tracked to the cell level

– Activation & deactivation of PDP context possible

– Sending and receiving of SMS is possible

– MS can receive paging for circuit switched services (optional)

– Data can not be transferred until a PDP context is activated. After thePDP context activation, the SGSN can send data to the MS withoutpaging at any time.

– Ready timer expire moves MS to the STANDBY state

GPRS MOBILITY MANAGEMENT STATE




• Standby State

– Subscriber is attached to the MM context

– Location tracked at RA level – If SGSN receives a packet for the MS, it pages in the RA. A PDP context

must be active.

– Activation of PDP context possible. If the MS sends data, it moves to the

ready state.

– MS can receive paging for CS services (optional)

– The MS Reachable Timer starts ticking when the MS enters the Standbystate & the MS is detached (IDLE state) upon its expiry (Implicit detach).

SESSION MANAGEMENT STATE




PDP CONTEXT ACTIVATION

• Process of assigning an IP address for becoming a part of the IP network

• One or more addresses can be assigned to an IMSI (MS).

• Contains mapping and routing information for transferring PDUs between MS andGGSN.

• Information includes: IP address, Access Point Name, QoS, Radio Priority….etc.

• Static addresses: address allocated by operator to an MS permanently and thisaddress is stored in the HLR.

• Dynamic addresses: GGSN dynamically allocates and releases addresses as PDPcontexts are activated and deactivated.

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CORE PLANNING ANG ENGINEERING.pdf