gsm call scenarios at a glance

8/3/2019 Gsm Call Scenarios at a Glance

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Title GSM Call Scenarios

Version V1.0

Author Praveen Devarmani

Ref:

Recommended Viewer ListGPS OAM , BSS Teams

Legend

Call Flow:- MS to Network Side

Call Flow:- Network to MS side


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Publication History

V1.0

09w32 Creation


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Mobile is Switched On

Network Attachment

Network Attachment

Network attachment is the process of selecting an appropriate

the mobile station to provide the available services, and makin

network. The process starts when the mobile station is switche

mobile station enters the idle mode

The network attachment process consists of the followintasks:

Step 1 Cell identification

When a mobile station is switched on, it attempts to make con

performing the following actions:

1)Measure the BCCH channels

2)Search for a suitable cellThe mobile station measures the signal strength of the BCCH

Channel) channels received. It stores in list information about

channels, such as the signal strength and the frequency corre

channels

Step 2 PLMN selection(Selects GSM PLMN)

A suitable PLMN is chosen.

PLMN selection mechanism

The particular PLMN to be contacted can be selected either in

modes:

Automatic mode

In automatic mode, the mobile station will choose which PLMN

automatic mode is based on the existence of the preferred list

volatile memory in the SIM. This list includes a number of PLM

preference and is under control of the user. The most preferre

PLMN. The list is filled in by the user through a mechanism to

station manufacturer. Manual mode

In manual mode, the user is presented a list containing all founThe user chooses one of the PLMNs from the list.


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Step 3 CELL selection(Selects Suitable ARFCN)

Cell selection is the process of selecting an appropriate cell (ra

mobile station to provide the available services.

Cell selection criteriaThe mobile station attempts to find a suitable cell by passing t

descending order of received signal strength; the first BCCH c

of requirements is selected. The requirements that a cell must

station can provide service from it, are:

It should be a cell of the selected PLMN

The mobile station checks whether the cell is part of the select

It should not be "barred"

The PLMN operator may decide not to allow mobile stations to

These cells may, for example, only be used for handover traffi

broadcast on the BCCH to instruct mobile stations not to acce The radio path loss between the mobile station and the selec

threshold set by the PLMN operator

Step 4 Location UpdateIn order to initiate a call or to receive a call, the mobile station

(BCCH plus CCCH) of the chosen cell. Then, it registers its pr

(registration process) by means of a location updating procedu

Step 5If No suitable cell found after cell selection process(MS enters

into Emergency Call Mode

If the mobile station is unable to find a suitable cell to access,

irrespective of the PLMN identity, and enters a "limited service

attempt to make emergency calls.

Mobile in Idle ModeIdle mode is the node in which mobile station does not have a

it for make or receive a call, but the Public Land Mobile Netwo

existence of the mobile station within the chosen cell.

PLMN area

A Public-Land-Mobile-Network (PLMN) area is the geographic

PLMN operator provides land mobile communication services

position within a PLMN area, the mobile user can set up calls t

network, or to a user of another network. The other network m

another GSM PLMN, or another type of PLMN. Other network

networks, can also call a mobile user who is active in the PLMWhen there are several PLMN operators, the geographical are

networks may overlap. National borders normally limit the exte


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Location area identity

Every radio transmitter in the PLMN broadcasts, via a control c

Identity (LAI) code to identify the location area that it serves.

When an MS is not engaged in a call, it automatically scans thbroadcasts transmitted by the base stations in the locality and

delivering the strongest signal. The LAI code broadcast by the

the location area in which the MS is currently situated. This LA

Subscriber Identity Module (SIM) of the mobile equipment.

As the MS moves through the network area the signal receive

channel gradually diminishes in strength until it is no longer the

MS re-tunes to the channel that has become dominant and ex

is broadcasting. If the received LAI code differs from that store

has entered another location area and initiates a location upda

change to the MSC. At the end of the procedure the LAI code

updated.Location area identity format


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Mobile Originating Call

MS BTS BSCRADIO RESOURCE ALLOCATION RADIO RESOURCE ALLOCATION RAD

MS to BTS(RACH)

CHANNEL REQUEST(RACH CCCH)

Reason(MOC) [Establisment Cause]

Random Reference Number BTS to BSC

CHANNEL REQUIRED

Channel Req (Reason, Rand ref Num)

Timing Advance

Frame NumberChannel Number

BSC to BTS

CHANNEL ACTIVATE

Channel number

Activation Type

Channel Mode (DTX??)

Channel Identification

Encryption information

Handover Reference

BS Power

MS Power

Timing Advance

BS Power ParametersMS Power Parameters

Physical Context

SACCH Information

BTS to BSC

CHANNEL ACTIVATE ACK

Frame Number

Channel number

BSC to BTS

IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Random Reference

[Full Imm. Assign Info]

BTS to MS(AGCH)SDCCH is Assigned

IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Reference



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LAYER 2 ESTABLISHMENT(LAPDm) [Data Link Layer] LAYER 2 ESTABLISHMENT(LAPDm)

MS to BTS(SDCCH)

CM_SERV_REQUEST(SABM)

CM_SERV_REQ

MS data

CM service type

Ciphering key sequence Number

Mobile station classmark

Mobile identity

BTS to MS BTS to BSC(EST_INDICATION)

CM_SERV_REQUEST(UA) CM_SERV_REQ

CM_SERV_REQ

MS data

CM service type



Mobile identity

AUTHENTICATION AUTHENTICATION

BSC to BTS

AUTH_REQ

BTS to MS Auth. Parameter -RAND AUTH_REQ(SDCCH) Cipher Key Sequence Number

Auth. Parameter -RAND Auth. Request Message Type

Cipher Key Sequence Number

Auth. Request Message Type

MS to BTS(SDCCH)

AUTH_RES(RESPONSE)

Authentication Parameter [SRES] BTS to BSC(SDCCH)

Auth Response message type AUTH_RES(RESPONSE)

Authentication Parameter [SRES]

Auth Response message type


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BSC to BTS

CM_SER_ACCEPT

BTS to MS CM Service Accept message type

CM_SER_ACCEPT

CM Service Accept message type


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CIPHERING CIPHERING

BSC to BTS

ENCR_CMD(SDCCH)

BTS to MS KC (Ciphering Key)

CIPHER_MODE_CMD(SDCCH) CIPHER_MODE_CMD

A5/X information

MS to BTS(SDCCH)

CIP_MODE_COMPLETE

Cipher mode complete Message type BTS to BSC(SDCCH)

Mobile equipment identity CIP_MODE_COMPLETECipher mode complete Message type

Mobile equipment identity

IMEI CHECK IMEI CHECK

BSC to BTS

IDENT_REQUEST(SDCCH)

BTS to MS Identity Request message type

IDENT_REQUEST(SDCCH) Identity type(IMEI)

Identity Request message type

Identity type(IMEI)

MS to BTS(SDCCH)

IDENT_RSP

Mobile Identity(IMEI) BTS to BSC(SDCCH)

IDENT_RSP

Mobile Identity(IMEI)

TMSI REALLOCATION TMSI REALLOCATION

BSC to BTS

BTS to MS TMSI_REAL_CMD(SDCCH)

TMSI_REAL_CMD(SDCCH) TMSI Number

TMSI Number LAI

LAI Mobile Identity

Mobile Identity

MS to BTS(SDCCH)

TMSI_REAL_COMPLETE

BTS to BSC(SDCCH)

TMSI_REAL_COMPLETE


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SETUP SETUPMS to BTS(SDCCH)

SETUP

Bearer Capablities BTS to BSC(SDCCH)

Calling party sub- address SETUP

Called party BCD number Bearer Capablities

Called party sub-address Calling party sub- address S

Called party BCD number B

Called party sub-address C

C

C

C

BSC to BTS

BTS to MS CALL_PROCEEDING(SDCCH)

CALL_PROCEEDING(SDCCH)

ConnectingDispalyed in Mobile

TCH ALLOCATION TCH ALLOCATION

A

BSC to BTS C

PHY_CONTEXT_REQ L

Query for Situation on Air Interface PC

BTS to BSC(SDCCH) D

PHY_CONTEXT_CONF I

Send MS Power to BSC C

Sends BTS Power to BSC

Sends TA info to BSC

BSC to BTS

CHANNEL_ACTIVATATION

Activation Type

Channel Mode



Handover Reference

BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC(SDCCH)

CHAN_ACT_ACK

Channel Number

Frame Number


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BSC to BTS

ASSIGNMENT_CMD(SDCCH)

BTS to MS Data of the TCH [TRX Info, Time Slot]


Data of the TCH [TRX Info, Time Slot]

TCH ALLOCATED HERE for MS


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LAYER 2 ESTABLISHMENT(LAPDm) LAYER 2 ESTABLISHMENT(LAPDm) L

MS to BTS(FACCH) BTS to BSC

FACCH/SABM EST_IND

Request for Lapdm layer2 connection Channel Number (which TCH Time Slt)

Link Identifier (C1 & C2)

BTS to MS L3 Information

(UA)(FACCH)

MS to BTS

ASSIGNMENT_COMPLETE

RR causeCell identifier

Chosen channel BTS to BSC

Chosen encryption algorithm ASSIGNMENT_COMPLETE

Indicates Signalling Link is Estb Successfully RR cause etcA

R

SDCCH RELEASE SDCCH RELEASE

BSC to BTS

RF_CHAN_RELEASE

Channel number [to be released]

BTS to BSC

RF_CHAN_RELEASE_ACK

Channel number [released]

ALERT ALERT

A

BSC to BTS A

BTS to MS ALERT/PROGRESS F

ALERT/PROGRESS Alerting Messge type U

Alerting Messge type Facility P

Facility User -User

User -User Progress indicator

Progress indicator

C

BSC to BTS C

BTS to MS CONNECT F

CONNECT P

BOTH USERS START CONVERSATION C

C

MS to BTS


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CONNECT_ACKNOWLEDGEIndicates call is going on and charges Applies BTS to BSC

CONNECT_ACKNOWLEDGE


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CALL RELEASE CALL RELEASE

MS to BTS

DISC

Disconnect message type BTS to BSC

Cause(Normal Clearing Examlple)-Reason DISC

Facility

Progress indicator

User-user

MS side user Releases the call

BSC to BTS

BTS to MS REL(RELEASE)REL(RELEASE) Release Cause

Release Cause

MS to BTS

RELEASE COMPLETE

Release Cause BTS to BSC

RELEASE COMPLETE

Release Cause

Traffic Channel RELEASE (by MS) Traffic Channel RELEASE

BSC to BTS

BTS to MS CHANNEL_RELEASE

CHANNEL_RELEASE Release Cause

Release Cause

BSC to BTS

DEACTIVATE_SACCH

MS to BTS Channel number

FACCH/DISC (LAPDm)

Request for Layer 2 connection Release

BTS to MS

FACCH/UA (LAPDm)

Confirmation of Layer 2 Connnection Release BTS to BSC

RELEASE_INDICATION

Channel number

Link Identifier

Release of Air Interface connection

Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX)

BSC to BTS

RF_CHN_RELEASE

Channel number (to be released)


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BSC requests to BTS for TRX release on airInterface

BTS to BSC

RF_CHN_RELEASE_ACK

TRX release acknowledge

Channel number ( which is released)


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MS to MS (Within PLMN)

Mobile Terminating Call

MS BTS

PAGING PAGING

MSC to BSC

PAGING_CMD

MSC to BSC Paging request type

PAGING_REQUEST Message type

Paging request type Page mode

Message type Channels needed for Mobiles

Page mode Mobile identitiesChannels needed for Mobiles P3 rest octets

Mobile identities TMSI

P3 rest octets IMSI

TMSI CELL Ids

IMSI

CELL Ids

Response to Paging Request

RADIO RESOURCE ALLOCATION RADIO RESOURCE ALLOCATION

MS to BTS(RACH)


Reason(MOC) [Establisment Cause]


CHANNEL REQUIRED


Timing Advance

Frame Number

Channel Number

BSC to BTS

CHANNEL ACTIVATE

Channel number

Activation Type




Handover Reference


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BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC


Frame Number

Channel number

BSC to BTS

IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Random Reference



IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Reference


LAYER 2 ESTABLISHMENT(LAPDm) LAYER 2 ESTABLISHMENT(LAPDm)

MS to BTS(SDCCH)PAGING_RESPONSE(SABM)

MS data

Request for Lapdm layer2 connection

BTS to BSC(EST_INDICATION)

PAGING_RESPONSE

Paging response message type

BTS to MS Ciphering key sequence Number

PAGING_RESPONSE(UA) Spare half octet

Mobile Stattion ClassMark

Mobile Identity


BSC to BTS

AUTH_REQ

BTS to MS Auth. Parameter -RAND

AUTH_REQ(SDCCH) Cipher Key Sequence Number


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Auth. Parameter -RAND Auth. Request Message Type



MS to BTS(SDCCH)

AUTH_RES(RESPONSE)

Authentication Parameter [SRES] BTS to BSC(SDCCH)Auth Response message type AUTH_RES(RESPONSE)



CIPHERING CIPHERING

BSC to BTS

ENCR_CMD(SDCCH)

BTS to MS KC (Ciphering Key)


A5/X information

MS to BTS(SDCCH)

CIP_MODE_COMPLETE


Mobile equipment identity CIP_MODE_COMPLETE

Cipher mode complete Message type



BSC to BTS


BTS to MS Identity Request message type



Identity type(IMEI)

MS to BTS(SDCCH)

IDENT_RSP


IDENT_RSP


TMSI REALLOCATION TMSI REALLOCATION

BSC to BTS


TMSI_REAL_CMD(SDCCH) TMSI NumberTMSI Number LAI


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LAI Mobile Identity

Mobile Identity

MS to BTS(SDCCH)

TMSI_REAL_COMPLETE

BTS to BSC(SDCCH)

TMSI_REAL_COMPLETE

SETUP SETUPBTS to MS(SDCCH)

BSC to BTS(SDCCH)

SETUP

Bearer Capablities

Calling party sub- address

BTS to MS Called party BCD number

SETUP Called party sub-address

Bearer Capablities

Calling party sub- addressCalled party BCD number

Called party sub-address

MS to BTS(SDCCH)

CALL_CONF BTS to BSC(SDCCH)

Call confirmed message type CALL_CONF

Repeat Indicator

Bearer capability

Bearer capability

Cause

CC Capabilities

TCH ALLOCATION TCH ALLOCATION

BSC to BTS

PHY_CONTEXT_REQ

Query for Situation on Air Interface

BTS to BSC(SDCCH)

PHY_CONTEXT_CONF

Send MS Power to BSC

Sends BTS Power to BSC

Sends TA info to BSC

BSC to BTS

CHANNEL_ACTIVATATION

Activation Type

Channel Mode



Handover Reference

BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information


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BTS to BSC(SDCCH)

CHAN_ACT_ACK

Channel Number

Frame Number

BSC to BTSASSIGNMENT_CMD(SDCCH)

BTS to MS Data of the TCH [TRX Info, Time Slot]



TCH ALLOCATED HERE for MS

LAYER 2 ESTABLISHMENT(LAPDm) LAYER 2 ESTABLISHMENT(LAPDm)

MS to BTS(FACCH) BTS to BSC

FACCH/SABM EST_IND

Request for Lapdm layer2 connection Channel Number (which TCH Time Slt)

Link Identifier (C1 & C2)

BTS to MS L3 Information(UA)(FACCH)

MS to BTS

ASSIGNMENT_COMPLETE

RR cause

Cell identifier

Chosen channel BTS to BSC

Chosen encryption algorithm ASSIGNMENT_COMPLETE

Indicates Signalling Link is Estb Successfully RR cause etc

SDCCH RELEASE SDCCH RELEASE

BSC to BTS

RF_CHAN_RELEASE

Channel number [to be released]

BTS to BSC

RF_CHAN_RELEASE_ACK

Channel number [released]

ALERT ALERT

BTS to MS

ALERT/PROGRESSAlerting Messge type

Facility BSC to BTS

User -User ALERT/PROGRESS

Progress indicator Alerting Messge type

Facility

BTS to MS User -User

CONNECT Progress indicator

Connect message type BSC to BTS

Facility CONNECT

Progress indicator

Connected number

Connected subaddress

User-userMS to BTS


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CONNECT_ACKNOWLEDGE

Indicates call is going on and charges Applies BTS to BSC

CONNECT_ACKNOWLEDGE

Indicates call is going on and charges

Applies

CALL RELEASE CALL RELEASE

BTS to BSC

DISC

MS to BTS

DISC

MS to BTS

REL(RELEASE)Release Cause BTS to BSC

REL(RELEASE)

Release Cause

BTS to BSC

MS to BTS RELEASE COMPLETE

RELEASE COMPLETE Reason

Reason


BSC to BTS



Release Cause

BSC to BTS

DEACTIVATE_SACCH


FACCH/DISC (LAPDm)


BTS to MS

FACCH/UA (LAPDm)


RELEASE_INDICATION

Channel number

Link Identifier


Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX)

BSC to BTS

RF_CHN_RELEASE

Channel number (to be released)

BSC requests to BTS for TRX release on airInterface


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BTS to BSC

RF_CHN_RELEASE_ACK


Channel number ( which is released)


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BSC MSC HLR

VLR

HLR to VLR

UDT/BEGIN(Provide roamining number)

VLR to HLR

UDT/END(Provide roamining number)

G-MSC to MSC

E-Interface (Initial Address Message)

PAGING

MSC to BSC

PAGING

Paging request type

Message type

Page mode

Channels needed for Mobiles

Mobile identities

P3 rest octetsTMSI

IMSI

CELL Ids

RADIO RESOURCE ALLOCATION


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LAYER 2 ESTABLISHMENT(LAPDm)

BSC to MSC

PAGING_RESPONSE

Adds LAC to Paging Response

Adds CI to Paging Response

Sends SCCP Connection request to MSC

MSC to BSC

CONNECTION CONFIRMED

SCCP Connection Established

Now onwards Logical Conn exist betn MS-MSC

AUTHENTICATION

MSC to BSC

AUTH_REQ

Auth. Parameter -RAND




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BSC to MSC(SDCCH)

AUTH_RES(RESPONSE)



CIPHERING

MSC to BSC

CIPHER_MODE_CMD(SDCCH)

KC (Ciphering Key)

A5/X Algorithm info(Encryption Info)

BSC to MSC (SDCCH)

CIP_MODE_COMPLETE

Cipher mode complete Message type


IMEI CHECK

MSC to BSC



Identity type(IMEI)

BSC to MSC(SDCCH)

IDENT_RSP


TMSI REALLOCATION

MSC to BSC

TMSI_REAL_CMD(SDCCH)

TMSI Number

LAI

Mobile Identity


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BSC to MSC(SDCCH)

TMSI_REAL_COMPLETE

SETUPMSC to BSC(SDCCH)

SETUP

Bearer Capablities

BSC to MSC(SDCCH)

CALL_CONF

TCH ALLOCATION

MSC to BSC

ASSIGNMENT_REQUEST(SDCCH)

Channel type

Layer 3 header information

Priority

Circuit identity code

Downlink DTX flag

Interference band to be used

Classmark information 2


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LAYER 2 ESTABLISHMENT(LAPDm)

BSC to MSC

ASSIGNMENT_COMPLETE

RR cause etc

SDCCH RELEASE

ALERT

MSC to BSC MSC to G-MSC

ALERT/PROGRESS ADDRESS COMPLETE MESSAGE

Alerting Messge type

Facility

User -User

Progress indicator

MSC to BSC MSC to G-MSC

CONNECT ISUP(ANSWER MESSAGE)

BOTH USERS START CONVERSATION


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BSC to MSC

CONNECT_ACKNOWLEDGE

Indicates call is going on and charges Applies

CALL RELEASE ISDN to G-MSC to MSC

BSC to MSC ISUP(RELEASE)

DISC

Disconnect message type

Cause(Normal Clearing Examlple)-Reason

Facility

Progress indicator

User-user

BSC to MSC

REL(RELEASE)

Release Cause MSC to G-MSC to ISDN

ISUP(RELEASE COMPLETE)

BSC to MSC

RELEASE COMPLETE

Reason

Traffic Channel RELEASE

MSC to BSC

CLEAR_COMMAND

Layer 3 header information

Release Cause

BSC to MSC

CLEAR_COMPLETE

Radio Channel RELEASE (TRX)

MSC to BSC


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RLSD

MSC requests BSC to release SCCP resources

BSC to MSC

RLC

Release CauseSCCP Release Acknowledge


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G-MSC ISDN

ISDN to G-MSC

IAM(ISUP)

G-MSC to HLR

UDT/BEGIN(Send Routing Info)

HLR to G-MSC

UDT/END(Send Routing Info)


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G-MSC to ISDN

ADDRESS COMPLETE MESSAGE

G-MSC to ISDN

ISUP(ANSWER MESSAGE)


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LOCATION UPDATE SCENARIO WHERE VLR CHANGES A

MS BTSRADIO RESOURCE ALLOCATION RADIO RESOURCE ALLOCATION

MS to BTS(RACH)


Reason(Location Update) [Establisment Cause]


CHANNEL REQUIRED


Timing Advance

Frame Number

Channel Number

BSC to BTS

CHANNEL ACTIVATE

Channel number

Activation Type

Channel Mode (DTX??)Channel Identification


Handover Reference

BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC


Frame Number

Channel number

BSC to BTS

IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Random Reference



IMM_ASS_CMD

Channel Number

Timing Advance

Frame Number

Reference[Full Imm. Assign Info]


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Location Update Request Location Update Request

MS to BTS(SDCCH)

LOC_UPDATE_REQUEST(SABM)


Mobile station classmarkMobile identity

Location area identification

Locatio Updating request Message type

OLD LAC Info

BTS to MS BTS to BSC(EST_INDICATIO

LOC_UPDATE_REQUEST(UA) LOC_UPDATE_REQUEST

Ciphering key sequence Num


Mobile identity

Location area identification

Locatio Updating request Me

OLD LAC Info


B

AUTH_REQ

BTS to MS Auth. Parameter -RAND

AUTH_REQ(SDCCH) Cipher Key Sequence Numb

Auth. Parameter -RAND Auth. Request Message Typ



MS to BTS(SDCCH)

AUTH_RES(RESPONSE)

Authentication Parameter [SRES] BTS to BSC(SDCCH)

Auth Response message type AUTH RES(RESPONSE)


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CIPHERING CIPHERING

B

ENCR_CMD(SDCCH)BTS to MS KC (Ciphering Key)


A5/X information

MS to BTS(SDCCH)

CIP_MODE_COMPLETE


Mobile equipment identity CIP_MODE_COMPLETE

Cipher mode complete Mess



B


BTS to MS Identity Request message ty



Identity type(IMEI)

MS to BTS(SDCCH)

IDENT_RSP


IDENT_RSP


TMSI REALLOCATION TMSI REALLOCAT

B


TMSI_REAL_CMD(SDCCH) TMSI Number

TMSI Number LAI

LAI Mobile Identity

Mobile Identity

MS to BTS(SDCCH)


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LOCATION UPDATE ACCEPT LOCATION UPDATE A

B

BTS to MS LOCATION UPDATE ACCEPTLOCATION UPDATE ACCEPT(SDCCH) TMSI Number

TMSI Number LAI

LAI Mobile Identity

Mobile Identity Location Updating Accept m

Location Updating Accept message type




Release Cause

DEACTIVATE_SACCH

MS to BTS Channel numberFACCH/DISC (LAPDm)


BTS to MS

FACCH/UA (LAPDm)


RELEASE_INDICATION

Channel number

Link Identifier

Release of Air Interface conne

Radio Channel RELEASE (TRX) Radio Channel RELEASE (T

RF_CHN_RELEASEChannel number (to be relea

BSC requests to BTS for TRX


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INTRA BTS HANDOVER :MS CHANGES ONE CELL to OTHER WITHIN ONEIn intra-BTS handover, a new channel in the same BTS is

assigned to the MS.The intra-BTS handover does notdistinguish whether the new channel is just on another

timeslot in the same TRX (frequency) or whether the TRX

changes as well.

MS BTS BSCActive Phase of call going on using old channel Active Phase of call going on using old channel

BSC to BTS

CHANNEL ACTIVATE

Channel number

Activation Type



Encryption informationHandover Reference

BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC


Frame Number

Channel number

BSC to BTS

HND_CMD/ASS_CMD

BTS to MS OR

HND_CMD/ASS_CMD(FACCH) HND_CMD/ASS_CMD

Hand Over Reference Hand Over Reference

Data of the TCH [TRX Info, Time Slot] Data of the TCH [TRX Info, Time Slot]


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Handover Access Handover Access

MS to BTS

HND_ACCESS

hand Over reference

MS to BTS

HND_ACCESS

hand Over reference

Max. 4 times not after ASS_CMD only after

HND_CMD

MS to BTS

HND_ACCESS

hand Over reference

MS to BTS

HND_ACCESS

hand Over reference

MS to BTS

SABM(FACCH) MS to BTS

ESTABLISH_INDICATION

BTS to MS

UA(FACCH)

MS to BTS

HND_COMPLETE

OR BTS to BSC

ASSIGNMENT_COMPLETE HND_COMPLETE

Handover complete message type OR

RR cause ASSIGNMENT_COMPLETE

Mobile observed time difference

PREVOUSLY OCCUPIED RESOURCE FREE PREVOUSLY OCCUPIED RESOURCE FREE

BSC to BTS

RF_CHAN_RELEASE

BTS to MSC

RF_CHAN_RELEASE_ACK

Active Phase of call strarts using new channel Active Phase of call strarts using new channel


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INTRA BSC HANDOVER: MS CHANGES from ONE BTS to ANOTHER BTS WI

MS BTS BSCActive Phase of call going on using old channel of old BTS

The measurement results on the currently used traffic channel

suggest an intra-BTS handover. The decision is made by the BSC.

BSC to BTS

CHANNEL ACTIVATE to New BTS

Channel number

Activation Type




Handover ReferenceBS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC

CHANNEL ACTIVATE ACK from New BTS

Frame Number

Channel number

BSC to BTS

HND_CMD to OLD BTS

BTS to MS Hand Over Reference

HND_CMD(FACCH) to OLD BTS Data of the TCH [TRX Info, Time Slot]

Hand Over Reference



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Handover Access Handover Access

MS to BTS

HND_ACCESS

hand Over reference

BTS TO MS

PHYSICAL_INFO(New Timing Advance Value)

MS to BTS

HND_ACCESS

hand Over reference

BTS TO MS

PHYSICAL_INFO(New Timing Advance Value)

MS to BTS

SABM(FACCH) MS to BTS


BTS to MS

UA(FACCH)

MS to BTS

HND_COMPLETE

Handover complete message type BTS to BSC

RR cause HND_COMPLETE

Mobile observed time difference

PREVOUSLY OCCUPIED RESOURCE FREE PREVOUSLY OCCUPIED RESOURCE FREE

BSC to BTS

RF_CHAN_RELEASE

BTS to MSC

RF_CHAN_RELEASE_ACK

Active Phase of call strarts using new channel of New BTS


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INTRA MSC HANDOVER -MS CHANGES BTS FROM ONE BSC TO BTS OF ANOTHER BSC(EXTERNAL HANDOVER)MS READ THE NOTE FIRST OLD/NEW NEW

BTS BSC

Active phase of the call using the old BTS/BSC

MSC to NEW BSC HND_REQ

HND_REQUEST

Channel type

NEW BSC to NEW BTS Encryption information

CHANNEL ACTIVATE to New BTS Circuit identity code

Channel number Classmark information 1

BS Power Classmark information 2

MS Power Classmark information 3

Channel Mode (DTX??) NEW BSC to MSC

Connection Confirmed(SCCP c

NEW BTS to NEW BSC

CHAN_ACT_ACKG

Frame Number

Channel number NEW BSC to MSC

HND_REQUEST_ACK(HANDOV

Layer 3 information

Chosen channel

OLD BSC to OLD BTS(FACCH)HND_CMD


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Handover Reference Target Frequecy

Channel Information Time SlotOLD BTS to MS (FACCH)


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HND_CMD

Handover ReferenceChannel Information

Target Frequecy

Time Slot

Handover Access Handover Access Handover Access

MS to NEW BTS

HND_ACCESS

hand Over reference

NEW BTS TO MS

PHYSICAL_INFO(New Timing

Advance Value)

MS to NEW BTS

HND_ACCESS

hand Over reference NEW BTS to NEW BSC

HANDOVER_DETECT

NEW BTS TO MS NEW BTS to NEW BSC

PHYSICAL_INFO

(New Timing Advance Value) HANDOVER_DETECT

MS to NEW BTS

SABM(FACCH) NEW BTS to NEW BSC


NEW BTS to MS

UA(FACCH)

MS to NEW BTS

HND_COMPLETE

Handover complete message type NEW BTS to NEW BSC

RR cause HND_COMPLETE NEW BSC to MSC

Mobile observed time diff HND_COMPLETE

Cause

Cell identifier

Chosen channel

Chosen encryption algorithmTraffic Channel RELEASE (by MS) Traffic Channel RELEASE Traffic Channel RELEASE

OLD BSC to OLD BTS

OLD BTS to MS CHANNEL_RELEASE



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Release Cause

OLD BSC to OLD BTSDEACTIVATE_SACCH

MS to OLD BTS Channel number

FACCH/DISC (LAPDm)

Request for Layer 2 connection

Release

OLD BTS to MS

FACCH/UA (LAPDm)

Confirmation of Layer 2

Connnection Release OLD BTS to OLD BSC

RELEASE_INDICATION

Channel number

Link Identifier


Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX

OLD BSC to OLD BTS

RF_CHN_RELEASEChannel number (to be released)

BSC requests to BTS for TRX release

on air Interface

OLD BTS to OLD BSC

RF_CHN_RELEASE_ACK


Channel number

( which is released)


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INTRA MSC HANDOVER -MS CHANGES BTS,BSC FROM ONE MSC TO BTS,BSC OF ANOTMS READ THE NOTE FIRST BTS A A

BSC MSC

Active phase of the call using the old BTS/BSC

BSC A to MSC AHND_REQUIRED E Interface

MSC A to MSC B

HND_REQUEST

MSC B to MSC A

HND_REQUEST_ACK

(HND_CMD)

Channel type

Encryption informatio

Circuit identity code

Classmark informatio



Cell identifier (target B

Interference band to b

Current Channel Info

MSC A to BSC A Handover Cause(HND_CMD) Cell identifier (Curren


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BSC to BTS

CHANNEL ACTIVATE to

New BTS

Channel number

Activation Type




Handover Reference

BS Power

MS Power

Timing Advance

BS Power Parameters

MS Power Parameters

Physical Context

SACCH Information

BTS to BSC MSC A to MSC


from New BTS ISUP(IAM)

Frame Number

Channel number MSC B to MS

ISUP(ACM)

BSC to BTS

HND_CMD to OLD BTS

BTS to MS Hand Over Reference MSC B to MS

HND_CMD(FACCH) to OLD

BTS

Data of the TCH [TRX Info,

Time Slot]

HND_DETECT(P

Signalling)

Hand Over Reference

Data of the TCH [TRX Info,

Time Slot] MSC B to MSC

ISUP(ANM)


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Handover Access Handover Access Handover Access

MS to BTS

HND_ACCESS

hand Over reference

BTS TO MS


Advance Value)

MS to BTS

HND_ACCESS

hand Over reference

BTS TO MS


Advance Value)

MS to BTSSABM(FACCH) MS to BTS


BTS to MS

UA(FACCH)

MS to BTS Act

HND_COMPLETE

BTS to BSC

HND_COMPLETE BSC to MSC

Handover complete message

type HND_PERFORMED

RR cause CauseMobile observed time

difference Cell identifier MSC B to M

Chosen channel HND_COMPLET

Chosen encryption

algorithm

Traffic Channel RELEASE (by MS) Traffic Channel RELEASE Traffic Channel RELEASE

MSC to BSC

CLEAR_COMMAND

BSC to BTS Layer 3 header information

BTS to CHANNEL_RELEASE Release Cause


Release Cause


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BSC to BTS

DEACTIVATE_SACCH


FACCH/DISC (LAPDm)

Request for Layer 2

connection Release

BTS to MS

FACCH/UA (LAPDm)

Confirmation of Layer 2

Connnection Release BTS to BSC

RELEASE_INDICATION

Channel number BSC to MSC

Link Identifier CLEAR_COMPLETE

Release of Air Interface

connection


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Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX) Radio Channel RELEASE (TRX)

BSC to BTS

RF_CHN_RELEASE

Channel number (to be

released)

BSC requests to BTS for

TRX release on air Interface MSC to BSC

BTS to BSC RLSD

RF_CHN_RELEASE_ACK

MSC requests BSC to

release SCCP resources


Channel number

( which is released) BSC to MSC

RLC

Release Cause

SCCP Release

Acknowledge


69/71


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SL No:- Reference

1 GSM_Messages.pdf

2 GSM_Book-Gunnar_Heine.pdf

3

4

5

6


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Links\\netapp1\proptima\Presentations\GSM_Presentations\Reference_Docs_PPT's\G

SM_Messages.pdf

\\netapp1\repo-nmcgps\Presentations\GSM_Book-Gunnar_Heine.pdf
http://../asrini/Local%20Settings/Temporary%20Internet%20Files/OLK3/GSM_Messages.pdfhttp://../asrini/Local%20Settings/Temporary%20Internet%20Files/OLK3/GSM_Messages.pdfhttp://netapp1/repo-nmcgps/Presentations/GSM_Book-Gunnar_Heine.pdfhttp://netapp1/repo-nmcgps/Presentations/GSM_Book-Gunnar_Heine.pdfhttp://../asrini/Local%20Settings/Temporary%20Internet%20Files/OLK3/GSM_Messages.pdfhttp://../asrini/Local%20Settings/Temporary%20Internet%20Files/OLK3/GSM_Messages.pdf

gsm call scenarios at a glance

Documents