Wireless and Mobile Network Architectures

Kwangwoon Univ.http://netcom.kw.ac.kr

Wireless and Mobile Network Architectures

Wireless and Mobile Wireless and Mobile Network ArchitecturesNetwork Architectures

Chapter 7Chapter 7

PACS Network SignalingPACS Network Signaling



PACS Network SignalingPACS Network Signaling

We describes network signaling for the Personal Access We describes network signaling for the Personal Access Communications System (PACS)Communications System (PACS)

PACS supports basic call control, roaming, and handoff PACS supports basic call control, roaming, and handoff managementmanagement

Does not use MSCs or HLR/VLR, but uses Advanced IntDoes not use MSCs or HLR/VLR, but uses Advanced Intelligent Network (AIN) protocol with an Access Manager elligent Network (AIN) protocol with an Access Manager (AM), AIN switch, and AIN SCP, SSP(AM), AIN switch, and AIN SCP, SSP



Advanced Intelligent Network (AIN)Advanced Intelligent Network (AIN)

By taking full advantage of the network intelligence generBy taking full advantage of the network intelligence generated by SS7 advancements ated by SS7 advancements

the Advanced Intelligent Network (AIN) can deliver new anthe Advanced Intelligent Network (AIN) can deliver new and profitable services to subscribers. d profitable services to subscribers.

In the AIN environment, new services are not tied to the cIn the AIN environment, new services are not tied to the call-processing logic of individual switching systems, but aall-processing logic of individual switching systems, but are defined through the interworking of these switches and re defined through the interworking of these switches and other network elements. other network elements.

A switch is alerted to the need for AIN processing through A switch is alerted to the need for AIN processing through various types of triggers that can accompany a call. various types of triggers that can accompany a call.



PACS ArchitecturePACS Architecture



PACS Network InterfacesPACS Network Interfaces

The RPCU provides management and control functions between the RP and the local exchange network.

The access manager (AM) in the RPCU, it provides: radio control : managing the RPs, trunk provisioning, RP to RP li

nk transfers non-radio service control : call control (managing the B channel

s), switching, routing The RPCU has to deal with inter-RPCU handoff (similar to inter-BSC

handoff) and inter-RP handoff. Note: an AM is also located in the AIN SCP; the two interact with th

e ISDN/AIN Switch providing tunneling/de-tunneling (i.e., encapsulation) of the ISDN REGISTER messages over AIN.



The major goal of PACS network signalingThe major goal of PACS network signaling

Utilize the existing AIN network entities, such as AIN SCUtilize the existing AIN network entities, such as AIN SCP and SSPP and SSP

there is no need to create new entities, such as MSC, uthere is no need to create new entities, such as MSC, using in other PCS systems.sing in other PCS systems.

In PACS signaling, telephony switching functions are sepIn PACS signaling, telephony switching functions are separated from the PCS-related signalingarated from the PCS-related signaling

To achieve this goalTo achieve this goal Noncall-associated signaling is introduced to minimize the modi

fications to the AIN SSP; that is, the AIN SSP does not interpret the PCS-related or IS-41-like signaling message

Many functions of the MSC have been removed from the SSP and moved to the AM and RPCU

The creation of the RPCU introduces a new kind of handoff : inter RPCU handoff



AIN/ISDN SwitchAIN/ISDN Switch The AIN switch is equipped with SS7, ISDN, and AIN capabilities. SS7 ISUP is used in the switch to set up the trunks in call control

and intersystem handoff. The SS7 TCAP is used to support mobility management, and to tra

nsport AIN message between the switch and the SCP. Triggering and querying

Triggering is the process of identifying calls that need AIN handling Querying is the process of assembling an AIN message to an AIN SCP

at a trigger detection point ISDN/AIN Interworking

Noncall-associated (NCA) signaling provides a generic method for the SCP to communicate with an ISDN connected device through the switch

PACS Network ElementsPACS Network Elements



PACS Network ElementsPACS Network Elements

AIN SCPAIN SCP The AIN SCP provides the service logic, database, and operation

capabilities to support HLR, VLR, AM and Auc. The SCP communicates with the switch using AIN TCAP and the

external PCS database using the IS-41 protocol. The HLR contains a PCS application process, end-user service p

rofiles, and accounting management capabilities.

Intelligent peripheralIntelligent peripheral 지능망 서비스에서 제공되는 각종 안내 멘트를 제공하고 ,

사용자와의 음성 인터페이스를 통해서 필요한 정보를 제공하며 , 서비스를 위해 필요한 각종 정보 ( 사용자 번호 , 비밀번호 , 서비스 선택 등 ) 를 수집하는 기능을 제공합니다 .



PACS Network InterfacesPACS Network Interfaces

AIN interfaceAIN interface During the call-processing procedure, the switch may detect the ne

ed for AIN processing at trigger detection points (TDPs) Then process between the AIN switch and the AIN SCP

ISDN interfaceISDN interface The RPCU communicates with the switch via ISDN basic rate interf

aces (BRIs)

Terminal Service Profile 1 (DN1)

Terminal Service Profile 2 (DN2)

Virtual Terminal 1 (DN1)

Virtual Terminal 2 (DN2)

B Channel

B Channel

D Channel

Switch RPCU

ISDN Basic Rate Interface



In ISDN signaling, every message contains a common In ISDN signaling, every message contains a common mandatory information element, referred to as the call mandatory information element, referred to as the call reference.reference.

ALERT ALERT B channel selection

CALL-PROC CALL-PROC call establishment from the called party to calling party

CONN , CON-ACK CONN , CON-ACK call acceptance by the called party

REL , REL-COMREL , REL-COM SETUPSETUP

Call initiation from calling party to called party FACILITYFACILITY

To request permission for a handoff operation (AIN switch RPCU)

REGISTERREGISTER To inform the VLR to carry out various operations



AIN/ISDN InterworkingAIN/ISDN Interworking

With NCA signaling, the switch provides interworking functWith NCA signaling, the switch provides interworking functions between the SCP/VLR(AIN) and the RPCU (ISDN).ions between the SCP/VLR(AIN) and the RPCU (ISDN).

The ISDN messages exchanged between the switch and The ISDN messages exchanged between the switch and the RPCU are of type the RPCU are of type REGISTERREGISTER

The AIN messages exchanged between the switch and thThe AIN messages exchanged between the switch and the VLR are of type e VLR are of type NCA_DataNCA_Data



NCA Signaling Initiated by the RPCUNCA Signaling Initiated by the RPCU The RPCU initiates NCA signaling by The RPCU initiates NCA signaling by

sending an ISDN REGISTER message to the sending an ISDN REGISTER message to the switch.switch.

The switch forwards the information to the The switch forwards the information to the VLR using an AIN NCA_DATA messageVLR using an AIN NCA_DATA message..

VLR Switch RPCU

REGISTER

REL-COM

NCA_Data

Invoke Component of FacilityMSG Type

envelopNCADataREGISTER

MSG Type

NCA_Data

Package Type

Unidirectional

Component Type

Invoke(Last)

Component

nCAData

(ISDN message)

(AIN message)

<NCA message format translation (ISDN to AIN)><NCA signaling initiated by the RPCU>



NCA Signaling Initiated by the VLRNCA Signaling Initiated by the VLR

The VLR initiates NCA signaling by sending The VLR initiates NCA signaling by sending an AIN NCA_DATA message to switch.an AIN NCA_DATA message to switch.

The switch sends an ISDN REGISTER The switch sends an ISDN REGISTER message to the RPCU.message to the RPCU.

VLR RPCUSwitch

REGISTER

REL-COM

NCA_Data

Invoke Component of FacilityMSG Type

envelopNCAData5REGISTER

MSG Type

NCA_Data

Package Type

Unidirectional

Component Type

Invoke(Last)

Component

nCAData

(ISDN message)

(AIN message)

<NCA signaling initiated by the VLR> <NCA message format translation (AIN to ISDN)>



NCA Signaling Initiated by the VLRNCA Signaling Initiated by the VLR

The REL-COM message is to clear the invocation The REL-COM message is to clear the invocation and the call reference of the REGISTER message.and the call reference of the REGISTER message.

The major goal of NCA signaling is to disassociate The major goal of NCA signaling is to disassociate the AIN SSP from PCS-related signaling.the AIN SSP from PCS-related signaling.

When the PCS signaling message is modified in When the PCS signaling message is modified in the feature, there will be no need to change the the feature, there will be no need to change the switch.switch.

NCA Signaling design featureNCA Signaling design feature The AIN SSP only translates the NCA signaling from one format

to another, the SSP does not interpret the message. In the ISDN interface between the AIN SSP and the RPCU, the

call reference is cancelled after every ISDN NCA message In the AIN interface between the AIN SSP and the AIN SCP, the

unidirectional TCAP message format is used instead of the general AIN transaction format- the query/response TCAP format



RegistrationRegistration

1. REGISTER(P-REGNOT)

OldVLR/AM

HLRNew

VLR/AMISDN/AIN

SwitchRPCU

2. NCA_Data(P-REGNOT)

8. NCA_Data(P-REGNOT-ACK)

9. REGISTER(P-REGNOT-ACK)

3. REL-COM

10. REL-COM

4. RegistrationNotification(INVOKE)

6. RegistrationCancellation(INVOKE) 5. RegistrationNotification

(RETURN RESULT)

7. RegistrationCancellation(RETURN RESULT)



Call OriginationCall Origination

1. REGISTER(P-CALL-ORG)

TerminatingSwitch

VLR/AMServing

ISDN/AIN SwitchRPCU

2. NCA_Data(P-CALL-ORG)

3. REL-COM

Rining

4. NCA_Data(P-CALL-ORG-ACK) 5. REGISTER

(P-CALL-ORG-ACK)

6. REL-COM

7. SETUP

8. Info_Collected

9. Analyzed_Route

10. IAM

11. ACM

13. CALL-PROC

14. ALERT

12. ANM

15. CONN

16. CONN-ACK



Call TerminationCall Termination

4. REGISTER(P-ALERT)

OriginatingSwitch

VLR/AMServing

ISDN/AIN SwitchRPCU

3. NCA_Data(P-ALERT)

5. REL-COM

Rining

1. Info_Analyzed

20. CONN

22. CONN-ACK

Serving SCPHLR

2. RouteRequest

6. REGISTER(ALERT_ACK)7. NCA_Data

(ALERT_ACK)8. REL-COM

9. RouteRequestAcknowledge

10. Analyze_Route

11. NCA_Data(RCID_ASSIGN) 12. REGISTER

(RCID_ASSIGN)

13. REL-COM

14. IAM

15. Termination_Attempt

16. Forward_Call

17. SETUP

18. ALERT

19. ACM

21. ANM



NewRPCU

OldRPCU

Old Switch

New Switch

NewRPCU

OldRPCU

Old Switch

New Switch

Before the ALT After the ALT

Intersystem HandoffIntersystem Handoff



Intersystem HandoffIntersystem HandoffOld

RPCU VLR/AM New SwitchNew

RPCU

The portable moves from old RPCU to the new RPCU

Old Switch

1. SETUP(ALT REQUEST)

3. IAM

2.CALL-PROC4. FACILITY

(ALT REQUEST)

5. FACILITY(ALT PERMISSION)

6. ANM

7. CONN

8. CONN-ACK

9. REGISTER(ALT COMPLETE)10. NCA_Data

(ALT COMPLETE)11. REL-COM

12. NCA_Data(ALT COMPLETE)13. REGISTER

(ALT COMPLETE)

14. REL-COM

15. DISC

16, REL

17. REL-COM



Inter-RPCU hand-off approachesInter-RPCU hand-off approaches

OldRPCU

NewRPCU

RP RP

Switch

OldRPCU

NewRPCU

RP RP

Switch

OldRPCU

NewRPCU

RP RP

Switch

OldRPCU

NewRPCU

RP RP

Switch

OldRPCU

NewRPCU

RP RP

Switch

(a) Before ALT (b) After ALT(Switch Loopback)

(c) After ALT(Direct Connect)

(d) During ALT(Three-way Calling Connection)

(e) After ALT(Three-way Calling Connection)



Inter-RPCU hand-off approachesInter-RPCU hand-off approaches

To minimize the impact of inter-RPCU handoff on the AIN SSP, tow anchorTo minimize the impact of inter-RPCU handoff on the AIN SSP, tow anchor-RPCU handoff approaches have been proposed.-RPCU handoff approaches have been proposed.

In the switch loopback,In the switch loopback, The old RPCU dials the new RPCU to make the connection through the switch. disadvantage : handoff consumes two more links between the switch and the

RPCUs In the Direct connection,In the Direct connection,

The RPCUs are connected with trunks Disadvantage : extra trunks are required to connect the RPCUs

and an inter-RPCUs handoff protocol is required Three-way calling connectionThree-way calling connection

Utilize the existing three-way calling facility of the AIN switch Minor modifications to the RPCU , does not consume extra trunks

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Wireless and Mobile Network Architectures