2g call advanced nsn5

8/6/2019 2G Call Advanced NSN5

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2G Call Scenario

(Advanced)



B

T

S

FCCH

SCH

BCCH

Idle Mode

B

T

S

RACH

AGCH

SDCCH

TCH

B

T

S

PCH

AGCH

RACH

SDCCH

TCH

O/G Mode I/C Mode



SMS Overview

SMS stands for Short Message Service SMS supports the sending and receiving of text, images,

animation and sound

SMS messages are originated and received by Short Messaging

Entities (SME). Examples of SMEs are: mobile phones; servers;personal computers

SMS messages contain up to 140 octets which is equivalent to:

160 Latin characters (7 Bit Coding) ± Text Mode

70 Unicode characters (double byte) e.g. Arabic Characters,

Chinese Characters

SMS messages can also contain up to 140 octets of binary

information



Basic Network Architecture

GMSC

HLR

MSSMSC MSC/

SGSN

VLR



Basic Network Architecture

1. Short Message Service Centre (SMSC) ± stores-and-forwards messages

2. GMSC receives messages from the SMSC, interrogates the

HLR for routing information and forward the messages to the

MSC or SGSN3. GMSC receives messages from the MSC or SGSN and

forwards them to the SMSC

4. Serving GPRS Support Node (SGSN) ± performs packet

switching functions for mobile stations in a geographical

area. The SGSN is used instead of the MSC when SMS info

is transferred over GPRS.



Message Flow SM-MT

Message

TransfersendRoutingInfo-

Delivery

ForShortMsg

forwardShortMessage

sendInfoFor-

MT-SMS

Message TransferDeliver Report

SM-Delivery

ReportStatus

Report

SMSC GMSC HLR MSC VLR

Page

Authenticate

MS



Message Flow SM-MO

Message

Transfer

Delivery

forwardShortMessage

sendInfoFor-

MO-SMS

Message Transfer

Delivery ReportDelivery

Report

Report

SMSC SMS-

IWMSC

HLR MSC VLR

Access Request

Authenticate

MS



Service Centre Functionality

The SC should be capable of ::

- submitting a short message to an MS, retaining the

responsibility of the message until

1) the report has been received; or 2) the validity period expires.

- receiving a short message from an MS.

- returning a report to the PLMN for previously received short

message.



SMS - GMSC Functionality

- reception of short message TPDU.

- inspection of the parameters.

- interrogating the HLR for mobile subscriber routing

information.

- transferring a short message to the MSC using routing

information obtained from HLR.

- receiving a report associated with short message from

the MSC and forwarding it to HLR and SC.



- reception of short message from GMSC.

- receiving information from VLR ie location area address.

- transferring the short message to the MS.

- relaying the delivery confirmation to the SMS-GMSC in a

delivery report.

MSC Functionality [ SM -MT ]



MSC Functionality [ SM -MO ]

- reception of short message from MS.

- inspection of TPDU parameters.

- examination of destination address.

- transferring the short message to the SMS-IWMSC.

- On receiving a report of the short message from the SMS-

IWMSC, relaying the report to the MS.



SMS - IWMSC Functionality

- reception of short message from MSC.

- transferring the short message to the SC.

- If a report associated with the short message is received from

the SC, -relaying the report to the MSC.

- On getting Alert from HLR, SMS-IWMSC will :

- inspect the SC address.

- transfer the alert message to the SC.



Originating Prepaid Charged call

Prepaid Call



Prepaid Call

� MSC/VLR functions identify that the call requires aMIN service and contacts the SSF.

� SSF determines which SCF must be contacted for

the service and identifies the call data, which must be

sent to the SCF. The SSF requests instructions from

the SCF about how to implement the MIN service.

� The SCF executes the logic for the requested service

and retrieves the necessary data from the SDF.

� The SCF sends instructions to SSF about the

processing of the service.



Prepaid Call

� The SSF performs actions to process the service,

interacting with the MSC/VLR¶s call control functions

where necessary.



Originating Charged Call 1(3)

1. The call is initiated from the PPS subscriber. The

OICK (Originating IN Call Key) in the VLR routes the

call to the SSF.

2. The SSF invokes the SCP where data about the callis collected to be transferred to the SDP (Service

Data Point)-Prepaid.

3. The data collected in Step 2 is sent to the SDP-

Prepaid where the Service Scenario of the account ischecked and Charging Analysis takes place. Allowing

and Barring Lists are also checked at this stage.




4. The SDP-Prepaid sends the result of the calculated

call duration together with call data such as

announcements to be played.

Further on the SCP orders the SSF to set up the calland to supervise it based on the call duration

calculated by the SDP-Prepaid.




HLR

IVR

VMS

SCP

Rating Engine

MSC/

VLR

S

S

F

1

2 3

4




5. If the call lasts longer than the call duration sent to the

SSF, the SSF notifies the SCP.

If there is still money left on the PPS subscriber¶saccount the SCP can request the SDP-Prepaid to make

another deduction from the account.

If such a request is made the SDP-Prepaid will make a

new Charging Analysis and send down the new callduration to the SCP which will pass it on to the SSF.




HLR

IVR

VMSSCP

Rating engine

MSC/

VLR

S

S

F

5




6. The call is ended.

7. The SSF notifies the SCP on the call disconnection

and a Final Report is sent from the SCP to the SDP-

Prepaid. It contains the remaining call duration which

is re-calculated back into monetary units and added

back to the account.

8. If USSD notification is used the SDP-Prepaid will

send the USSD information to the HLR.



CR BT

� CRBT Components

± MSC-SSP ( in-built into the Switch)

± Media Player

± Registration Server

± Content Repository

Voice Conversation (CRBT turned off)

Content Repository Registration Server

Intelligent peripheral (IP)

CRBT play

SS7 links

Calling party Called partyReceiver Switch (MSC)MSC

Similar to IN based solution. In this case the SCP

functionality is derived from the switch through

a potential switch upgrade / purchase of CRBT

feature from switch vendor

Ring Back Tone



Call flow for CR BT(Switch based)

Calling

PartyMSC Receiver MSC HLR Called Party

Voice Conversation

Initiate a Call

Ring Back Tone

IP

IAM

ACM

SRI

SRI ² ACK + CRBT ONPage the receiver

IAM

ACM

ANM

Answer

REL

RLC

Voice Conversation (CRBT turned off)



MMS ±Call Flow

2g call advanced nsn5

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