session mgmt in ps

8/3/2019 Session Mgmt in Ps

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UMTS Networks 1 Andreas Mitschele-Thiel 16-Nov-04

Communication Management

• Connection management (call control – CC)for CS mode

• Session management (SM) for PS mode

References:

• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks – Architecture,Mobility and Services. Wiley 2001, ch. 5.3

• 3G 23.060 GPRS, Service Description, ch. 9

• 3G 24.007 Mobile radio interface signalling layer 3, General aspects




Fundamental Difference BetweenCS and PS Communication

Connection (e.g. voice, CS data)

• clearly defined start and end

• no burstiness

minutes

connectionsetup

connectionrelease

Differences require

different solutions to• mobility mgmt and

• communication mgmt

Packet session (e.g. web surfing)

• start and end times are typically unknown to the UMTS system

• traffic is highly bursty

hours

seconds




Connection Management – CS Mode

Basic activities of connection management• number analysis (check called number for correctness, check of call

barring of calling number)

• set up of connection (according to routing rules)• collection of charging information

• release of connection

Types of calls

• normal voice call

• emergency call• data call (FAX, etc.)




Connection Management

Access Domain MSC/VLR Other Elements

PTCMOC

ConnectionManagement

POCMTC

A call consists of several call legs (parts of the call)

• Mobile Originated Call (MOC)

• Mobile Terminated Call (MTC)

• PSTN Originated Call (POC)

• PSTN Terminated Call (PTC)


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Connection Management

Network Interworking

• echo cancelation (2/4-line conversion echo, acustic echo)• modems and rate adapters

Charging

• Collection of charging information for each leg due to UMTS commercialmodel (subscriber, network operator, service provider, contentprovider)

• Fraud control between serving and home network

• Cost control by charged party• Itemized billing

Call Detail Record (CDR) – Charged party

– Terminal identity and class called address – Used 3G resources – QoS parameters – Serving 3G network and network element identities – Time stamps – MM information – CDR identity



C a l l C o n t r o l o f M o b i l e - T e r m i n

a t e d C a l l ( C S )



Service graph of Call Control entity - Network side

RELEASE

REQUEST

DISONNECTINDICATION

DISCONNECT

REQUEST

CALL INIT

NO CALL

PROCEEDING

CALL

DILIVERED

ACTIVE

CALL

RECEIVED

CONNECTREQUEST

MT CALL

CONFIRMED

CALL

PRESENT

NULL0

1

3

4

10

19

12

6

9

7

8

11

MNCC-

REL-

IND

MNCC-REJ-IND

MNCC-SETUP-REQ

MNCC-

DISC-

IND

MNCC-

DISC-

REQMNCC-

ALERT-

IND

MNCC-FACILITY-

IND

ANY STATE

EXCEPT 0ANY STATE

MNCC-

REL-

IND

0ANY STATE

EXCEPT 0,19

MNCC-

FACILITY

REQ

MNCC-SETUP-REQ

MNCC-REJ-IND

STATES

4,6,8,9,10

MNCC-REL-CNF

MNCC-

DISC-

IND

MNCC-

CALL-

CONF-IND

MNCC-

ALERT-

IND

MNCC-SETUP-

CNF

MNCC-

SETUP-CNF

MNCC-SETUP-COMPL-REQ

MNCC-CALL

PROC-REQ

CONNECT

INDICATION28

MNCC-

PROGRESS-

REQ MNCC-

ALERT-

REQ

MNCC-

SETUP-

RSP

MNCC-REL

REQ

(excerpt)

Output des Automaten:• Request (REQ),

• Response (RSP)

Input des Automaten:

• Indication (IND),

• Confirmation (CNF)



Service graph of Call Control entity - MS side

RELEASE

REQUEST

DISONNECT

INDICATION

STATES

3,4,7,8,9,10

DISCONNECT

REQUEST

CALL INIT

NO CALL

PROCEEDING

RELEASE

REQUEST

CALL

DELIVERED

ACTIVE

CALL

RECEIVED

CONNECT

REQUEST

MT CALL

CONFIRMED

CALL

PRESENT

NULL0

1

3

419

10

19

12

6

9

7

8

11

MNCC-SETUP-IND

MNCC-REJ-REQ

MNCC-REL-

REQ

MNCC-

DISC-IND

MNCC-

REL-

IND

MNCC-REJ-IND

MNCC-SETUP-REQ

MNCC-DISC-

REQ

MNCC-

DISC-

IND

MNCC-CA

CONF-REQ

MNCC-

SETUP-RSP

MNCC-

ALERT-

REQ

MNCC-

SETUP-RSP

MNCC-SETUP-

COMPL-IND (ERR)

MNCC-

DISC-

IND

MNCC-

DISC-

REQ

MNCC-SETUP-COMP-INDMNCC-SETUP-

CNF

MNCC-

SETUP-

CNF

MNCC-

ALERT-

IND

MNCC-REL-

REQ

MNCC-

PROGRESS-

IND

MNCC-CALL

PROC-IND

MNCC-REL-

CNF

MNCC-FACILITY-

IND

ANY STATE

EXCEPT 0ANY STATE MNCC-

REL-

IND

0ANY STATE

EXCEPT 0,19MNCC-

FACILITY

REQ

(excerpt)



Session Management – PS Mode

States of SM (state of PDP contexts)

– inactive: no packet data transfer, no valid routing information

– active: packet data transfer possible, valid routing information

Support for various packet data protocols (PDP)

Examples: IP, PPP, X.25

Attributes of packet session: PDP context

– defines all paramters of the packet data session by end-to-endattributes and QoS

– one PDP context per PS services with a certain QoS, e.g. for webserving, streaming video, packet voice, etc.



Session Management: States of PDP Context

A GPRS subscription contains the subscription of one or more PDP addresses

Each PDP address is described by one or morePDP contexts in the MS, SGSN, and GGSN

Each PDP context is associated with – A QoS profile

– a traffic flow template (TFT) to discriminateflows sharing the same PDP address

Every PDP context exists independently in one of

two PDP states

The PDP state indicates whether data transfer isenabled for that PDP address and TFT or not

GPRS subscription

PDPaddress

PDPcontext

PDP state

active

PDP state

inactive

Reference: 3G 23.060, ch 9

Field Description GSM UMTS



P D

P c o n t e x

t f i e l d s m

a i n t a i n e

d b y G G

S N

f o r

a P D P A

d d r e s s

Field Description GSM UMTS

IMSI International Mobile Subscriber Identity. X X

NSAPI Network layer Service Access Point Identifier. X X

MSISDN The basic MSISDN of the MS. X X

PDP Type PDP type; e.g. PPP or IP. X X

PDP Address PDP address; e.g. an IP address. X X

Dynamic Address Indicates whether PDP Address is static or dynamic. X X

APN in Use The APN Network Identifier currently used. X X

TEID Tunnel Endpoint Identifier. X X

TFT Traffic flow template. X X

QoS Profile Negotiated The quality of service profile negotiated. X X

SGSN Address The IP address of the SGSN currently serving this MS. X X

MNRG Indicates whether the MS is marked as not reachable for PS at theHLR.

X X

Recovery Indicates if the SGSN is performing database recovery. X X

GTP-SND GTP-U sequence number of the next downlink N-PDU to be sent

to the SGSN.

X X

GTP-SNU GTP-U sequence number of the next uplink N-PDU to be received

from the SGSN.

X X

Charging Id Charging identifier, identifies charging records generated by

SGSN and GGSN.

X X

Charging Characteristics The charging characteristics for this PDP context, e.g. normal,

prepaid, flat-rate, and/or hot billing.

X X

Trace Reference Identifies a record or a collection of records for a particular trace. X X

Trace Type Indicates the type of trace. X X

Trigger Id Identifies the entity that initiated the trace. X X

OMC Identity Identifies the OMC that shall receive the trace record(s). X X

S o u r c e : 3 G P P

2 3 . 0 6 0 -

4 . 1 . 0 , C h

1 3




Inactive state:

– no valid routing or mapping

information to process data related

to PDP address-> no data transfer

-> no updates due to location

changes (even in GPRS-attached

state)

PDP context activation (transition to

active state):

– MS-initiated PDP context activation

– network-requested PDP context

activation

Deactivate PDP Contextor PMM-DETACHED

Activate PDP

Context

PDP Context

INACTIVE

PDP Context

ACTIVE





Active state:

– valid routing or mapping

information to process data related

to PDP address (MS, SGSN, GGSN) – Requires MM state PMM-idle or

PMM-connected

-> data transfer possible

-> updates due to location changes

PDP context deactivation:

– PDP context deactivation procedure

– MM state changes to PMM-

detached

PDP context modification, e.g. to

modify QoS profile

Deactivate PDP Contextor PMM-DETACHED

Activate PDP

Context

PDP Context

INACTIVE

PDP Context

ACTIVE





Relation between PDP Context and MM

GPRS subscription

PDPaddress

PDPcontext

PDP state

inactive

PDP state

active

PDPcontext

PDPcontext

PDPcontext

Single

MM context

Relation between MM andPDP states:

• All PDP contexts of asubscriber are associatedwith the same MM contextfor the IMSI of thatsubscriber

• The MM state isindependent of the numberand state of PDP contextsfor the subscriber

• In both the PMM-IDLE andthe PMM-CONNECTEDstates, session managementmay or may not haveactivated a PDP context



UMTS Networks 15 Andreas Mitschele-Thiel 16-Nov-04 E x a m

p l e o

Cell_DCH connected active

URA_PCH connected active

Cell_FACH connected active




UE initiated service request

RAB allocation CN bearer allocation

Packet data transfer

RAB clearing CN bearer clearing

. . .For details see Kaaranen, ch 5.3.2

f

S t a t e s D u r i n g

P a c k e t

F l o w SGSN GGSNUTRANUE

SMPMMRRC

idle detached inactiveRRC conn. establishment

Cell_ DCH detached inactiveGPRS attach

(incl. authentication & security)Cell_DCH connected inactive

PDP context establishment (UE originated)Cell_DCH connected activeRAB allocation CN bearer allocation




. . .



UMTS Networks 16 Andreas Mitschele-Thiel 16-Nov-04 E x a m

p l e o f

S t a t e s D u r i n g

P a c k e t

F l o w

( c o n t ‘ d )

SGSN GGSNUTRAN





Cell_FACH connected active


idle detached inactive

Cell_DCH connected inactive


RRC connection release

PDP context deactivationand IMSI detach

Instead of cell_DCH, cell_FACH may be used for small messages

UESMPMMRRC

. . .(packet) paging incoming data

UE initiated service request

RAB allocation CN bearer allocation



. . .

PDP ctxt deletion




Service Request Procedures

Usage of procedure:

• MS in PMM-IDLE state:

-> request the establishment of a secure connection to a SGSN

– to send uplink signalling messages (e.g. PDP Context ActivationRequest) or

– to send user data or

– as paging response or – after regain of radio coverage

• MS in PMM-CONNECTED state:-> request resource reservation for active PDP contexts

Source: 3GPP 23.060-4.1.0, Ch 6.12




Service Request Procedure Initiated by MS

SGSNMS

2. Service Request

3. Security Functions

RNC

1. RRC Connection Request

8. Uplink PDU

1. RRC Connection Setup

4. Radio Access Bearer Assignment Request

6. Radio Access Bearer Assignment Response

5. Radio Bearer Setup


Complete

HLR GGSN

7. SGSN-Initiated PDP Context Modification

4. Service Accept

Service type: data• setup of signaling connection• allocation of resources for active

PDP context(s)Service type: signaling• setup of signaling connection,

e.g. to activate PDP context

If none exists for CS

F o r s e r v i c e

t y p e d a t a o n l y

For PMM-idle mode only




Service Request Procedure Initiated by Network

7. SGSN-Initiated PDP Context Modification Procedure

8. Downlink PDU

SGSNMS

5. Security Functions

RNC

3. RRC Connection Request

1. Downlink PDU

3. RRC Connec tion Setup

6. Radio Access Bearer AssignmentRequest

6. Radio Access Bearer AssignmentResponse


6. Radio Bearer SetupComplete

2. Paging

2. Paging

4. Service Request

HLR GGSN

3G-SGSN sends a pagingrequest to UTRAN when itreceives a downlink packet (e.g., a requestfor PDP context

activation, MT SMS, userdata) for an MS inPMM-IDLE state

The paging request

triggers the ServiceRequest procedure in theMS

NAS Protocol Architecture Supporting PS Mode




NAS Protocol Architecture Supporting PS Mode,MS side Source: 3GPP 24.007, Ch 5

MM-sublayer

G S M S

MNSMS-SAP

PMMSMS-SAPG M M SM - SA P

SESSION

M A N A G E M E N T

TI

G M M RE G -

SA P

CM

PD

G M M

SMREG-SAP

A ccess Stratum sublayer

RABMAS-SAP GMMAS-SAP

RRCPDCP

RABMSM-SAP

PDCPn-SAP

G M M RA BM _SA P

BM C

PDCP2-SAPDCP1-SAP

PDP

R A B M

RAB1-SAP

RABEntity

1

RA B

Entity

2RA B

Entity

n

RA B

Control

RABn-SAPRAB2-SAP

Suplemen.

Services

(SS)

MNSMS-SAP

GMMSS-SAP

TI

NAS Protocol Architecture Supporting CS/PS




NAS Protocol Architecture Supporting CS/PSMode, MS side

GMMSM-

SAP

MM-sublayer

GMM

GMM

coord

MNSMS-SAP

GMMREG

-SAP MMSMS-

SAP

MMCC-SAP MMSSSAP

PMMSMS

-SAP

MNSS-SAPMNCC-SAP

GMMSMS-

SAP

TITIPDP TI

CM

CC SSGSMS

TI

PD

MM MM

coord PD

SMREG-SAP

R A B M S M - S A P

RABM

RAB1-SAP

RAB

Entity

1

RAB

Entity

2RAB

Entity

n

RAB

Control

RABn-SAPRAB2-SAP

SM

G M M R

A B M - S A P

Access Stratum sublayer

RABMAS-SAP GMMAS-SAP

RRCPDCP

PDCPn-SAP

BMC

PDCP2-SAPPDCP1-SAP RR-SAP

GMMSSSAP

TI

GMMSS2SAP

Source: 3GPP 24.007, Ch 5

session mgmt in ps

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