WO2007038273A1 - Centralized management of a multi-mode wireless call - Google Patents

Abstract

A supervisory network (200) such as an IP Multimedia Subsystem is employed to manage a multiple-mode wireless subscriber (10) operating in a telecommunications system of circuit-switched (120) and packet-switched (110) wireless access networks. A protocol-translating interface (210) between the supervisory network and the circuit-switched wireless access (120) networks helps provide centralized feature management, and seamless handover of active calls from one wireless access network to another.

Description

Centralized Management of a Multi-Mode Wireless Call

Cross-Reference to Related Applications

This application is related to and claims the benefit of

commonly-owned U.S. Provisional Application no. 60/719,804, filed

September 23, 2005, and titled "An IMS-anchored Dual Mode Solution for

Roaming and Handover between GSM and WLAN Networks," incorporated

herein by reference.

Background of the Invention

The system described and claimed here concerns call management for

wireless telephone devices capable of operating in multiple modes such as

circuit-switched and packet-switched, realized as cellular (including digital

and analog), wireless IP such as Wi-Fi and WiMAX, and any other suitable

mode. The system permits a multiple mode wireless telephone to roam from

one network to another, and place and receive calls from any of those

networks. It also affords seamless mid-call handover from one network to

another and centralized management of call features for these wireless

subscribers. Brief Description of the Drawings

Figure 1 is a block diagram of a telecommunications system;

Figure 2 is a block diagram of a supervisory network;

Figure 3 is a block diagram of another telecommunications system;

Figures 4 and 5 are flow charts of procedures for registering a

multimode wireless subscriber in circuit-switched wireless access networks

and packet-switched wireless access networks, respectively;

Figures 6 and 7 are flow charts of procedures for re-registering a

multimode wireless subscriber as it roams from a packet-switched wireless

access network to a circuit-switched wireless access network and vice versa;

Figures 8-10 are flow charts of procedures for passing call feature

management from an access network to the IP Multimedia Subsystem (IMS);

Figure 11 is a block diagram of the telecommunications system of

Figure 3 further illustrating voice bearer components; and

Figures 12 and 13 are flow charts of procedures for call handover from

one wireless access network to another.

Description of the Invention

Figure 1 depicts a multimode wireless subscriber 10 operating in a

telecommunications network. The multimode wireless subscriber 10 has the

ability to place and receive calls through two or more access networks 100. These access networks 100 may utilize circuit switched or packet switched

(IP) technology as suits the application. A supervisory network 200

enhances this capability by providing management of a) calls placed and

received by the multimode wireless subscriber 10, b) call features available

to the multimode wireless subscriber 10, and c) roaming and handover

between the access networks 100. Although not shown, the supervisory

network 200 also may interface with non-wireless networks, such as the

public-switched telephone network.

The supervisory network 200 is shown in greater detail in Figure 2. In

this example, the supervisory network 200 is configured as an IP Multimedia

Subsystem (or IMS). The components of the IMS 200 illustrated in Figure

2, as well as Figures 3 and 11 discussed below, are dictated by industry

standards and explained in various publicly-available documents such as

3GPP TS 22.228 V8.0.0 (2006-06): Technical Specification, 3rd Generation

Partnership Project; Technical Specification Group Services and System

Aspects; Service requirements for the Internet Protocol (IP) multimedia core

network subsystem; Stage 1 (Release 8); and 3GPP TS 23.228 V7.4.0 (2006-

06): 3rd Generation Partnership Project; Technical Specification Group

Services and System Aspects; IP Multimedia Subsystem (IMS); Stage 2

(Release 7), incorporated here by reference. These are available from the

3rd Generation Partnership Project, European Telecommunications Standards Institute, 650, route des Lucioles 06921 Sophia- Antipolis Cedex,

France, and on the Internet at www.3gpp.org.

An interface such as a gateway or access router 210 provides a

connection point for the access networks 100. The IMS 200 also contains a

call session control function (CSCF) 220, a home subscriber server (HSS)

230, and one or more voice application servers 240. The voice application

servers 240, occasionally referred to as "voice feature servers" or just simply

as "application servers," provide centralized subscriber feature

implementation (e.g., call forwarding, call bearing) for the all of the access

networks. The voice application servers 240 may also provide management

in lieu of the HSS 230.

The IMS 200 also contains a management application server (MAS)

250. The management application server 250 provides applications, i.e.,

programs or instructions, to the IMS 200 for managing the roaming and

handover processes discussed below. The management application server

250 also functions as an interface between the IMS 200 and circuit-switched

access networks 100, communicating with the components of the IMS 200 in

a suitable format through an ISC (IP multimedia subsystem Service Control

interface) and with circuit-switched access networks 100 using a protocol

such as MAP (Mobile Application Part). For example, the management

application server 250 converts subscriber-signaling information in the IMS 200 to the MAP protocol of a circuit-switched access network 100, and

vice versa.

A specific implementation of the IMS 200 is shown in Figure 3.

There, the IMS 200 is connected to two access networks: a packet-switched

wireless (PSW) access network 110 and a circuit-switched wireless (CSW)

access network 120. Although not further defined or described in the

drawings, the PSW access network 110 is not limited to a specific format or

protocol, and may be implemented as a wireless LAN, Wi-Fi, WiMAX,

other IEEE 802 protocols, or any other wireless, packet-based or internet

protocol (IP) network, which may also be described as an IP-CAN (IP

Connectivity Access Network). Similarly, the CSW access network 120 is

not limited to any particular implementation, and may include any wireless,

circuit-switched network (e.g., GSM, CDMA, TDMA, AMPS (advanced

mobile cellular system), UMTS-CS (universal mobile telecommunications

system-circuit switched)).

The multimode wireless subscriber 10 is capable of accessing both the

PSW access network 110 and the CSW access network 120. An IP router

212 serves as the gateway/access router 210 for the PSW access network 110

and a signaling gateway 214 serves as the gateway/access router 210 for the

CSW access network 120. The CSW access network 120 comprises a home

location register (HLR) 130 and a mobile switching center (MSC) 140. Registration

Initially, the multimode wireless subscriber 10 powers up, seeking

entry into one of the access networks. The subscriber 10 may be configured

to arbitrarily select one particular network first before attempting a

connection to another. If the subscriber 10 attaches to the CSW access

network 120 first, an entry is made in the HLR 130 (Figure 4). The

subscriber 10 can then place and receive calls through that network.

Conversely, should the subscriber 10 instead attach to the PSW access

network 110, an entry is entered in the HSS 230 (Figure 5).

Under the presently-employed standard for the IP Multimedia

Subsystem, the IMS 200 would normally not forward registration

information to a CSW access network 120. However, should the IMS 200 in

question be configured to send such information, the CSW access network

120 could then receive registration information from the IMS 200. In that

event, when the multimode wireless subscriber 10 registers through the PSW

110, the management application server 250 would issue a message for the

HLR 130. In this instance, the management application server 250 is

emulating a visitor location register (VLR) for the CSW access network 120

(third box in Figure 5). Roaming between Access Networks

The multimode wireless subscriber 10 may have occasion to move

from an area covered by one access network to an area served by another

network. For example, the subscriber 10 may initially attach to the PSW

access network 110, but later move into an area served by a CSW access

network 120, detaching from the PSW access network 110 (Figure 6).

In such a case, the HSS 230 and the HLR 130 would be updated to reflect

this movement. Similarly, if the subscriber 10 moves from the CSW access

network 120 to the PSW access network 110, the HSS 230 is updated to

reflect the entry of the subscriber 10 (Figure 7). Optionally, the IMS 200

notifies the CSW access network 120 of this event. The management

application server 250 provides the applications for controlling the foregoing

processes (Figures 6 and 7).

CaIl Feature Management and Implementation

To provide uniformity and achieve efficiency in call management, the

features applied to the multimode wireless subscriber 10 are managed,

specified, and implemented by the IMS 200, not the access networks 110.

Such features may include call forwarding, call bearing, caller ID,

simultaneous ringing, distinctive ringing, and any others available to the

multimode wireless subscriber 10. This is accomplished in part by referring

all feature-related issues to the IMS 200. The specifics of call features for a

given multimode wireless subscriber 10 may be stored in the HSS 230 and

implemented by the voice application servers 240. Alternatively, the

feature set available to the multimode wireless subscriber 10 may be

managed by a voice application server 240 instead of the HSS 230.

If the multimode wireless subscriber 10 places or receives a call

through the PSW access network 110, that network will route the call to the

IMS 200, enabling a voice application server 240 to apply the feature

specifications for the multimode wireless subscriber 10 (Figure 8).

Similarly, if the multimode wireless subscriber 10 places or receives a call

through the CSW access network 120, the call is routed to the IMS 200 and

again the IMS 200 manages the features available to the subscriber 10

(Figures 9 and 10). (The management application server (MAS) 250 is also

invoked at this time so that it will be available to the IMS 200 for other functions.) As for the PSW access network 110, the HSS 230 or a voice

application server 240 specifies the features available to the multimode

wireless subscriber 10 and a voice application server 240 implements the

specific feature.

The CSW access network 120 can be configured to route the call from

the multimode wireless subscriber 10 to the IMS 200 in at least two ways. In

one method, an intelligent network trigger is provided to the CSW access

network 120, such that when the multimode wireless subscriber 10 places or

receives a call, the CSW access network 120 queries the IMS 200 (Figure 9).

This approach may use a CAMEL SCP (Customized Applications for

Mobile network Enhanced Logic) (Service Control Point) in the CSW access

network 120 with a previously-established trigger detection point. In an

alternative method, the multimode wireless subscriber 10 is assigned a

number (e.g., an MSISDN, the Mobile Station International ISDN Number)

having a prefix which forces the CSW access network 120 to route the call to

the IMS 200 (Figure 10).

The foregoing mechanisms insure centralized, uniform feature

management and implementation across multiple wireless access networks.

Management of an Active Call (Call in Progress) and Handover

A more detailed rendering of the telecommunications network of

Figure 3 is shown in Figure 11, introducing three additional components: a media gateway 260, a multimedia resource function controller 270, and a

media gateway control function 280. These three items are involved in the

handling and management of the voice bearer paths. The management

application server (MAS) 250 provides the applications for the following

handover processes (Figures 12 and 13).

When moving from one wireless access network to another (CSW to

PSW, or vice versa), the bearer path of the multimode wireless subscriber 10

engaged in a call is maintained through the transfer, so that there is no break

in the call, i.e., loss of speech packets or the circuit. Given the dual-mode

configuration of Figure 11, two scenarios are presented: moving from the

PSW access network 110 to the CSW access network 120 (Figure 12), and

the reverse (Figure 13).

In the former scenario (moving from the PSW access network to the

CSW access network), the multimode wireless subscriber 10 is initially

connected the PSW access network 110. The multimode wireless subscriber

10 then begins the transfer by attaching to the CSW access network 120,

while maintaining the original connection with the PSW access network 110.

The mechanics of attachment to the CSW access network 120 are the same

as required for registration of the multimode wireless subscriber 10 with the

CSW access network 120 described in connection with Figure 4. Once the

attachment to the CSW access network 120 has been successfully completed, - l i the multimode wireless subscriber 10 places a new call in the CSW access

network 120, which is routed to the IMS 200. The management application

server 250 then instructs the other party to the call to connect via the MGCF

280 (e.g., using third party call control issuing a "re-invite"), and then the

connection of the subscriber 10 to the PSW access network 110 can

be terminated.

In the second case, the call moves from the CSW access network 120

to the PSW access network 110. The multimode wireless subscriber 10

attaches to the PSW access network 110, registering with the IMS 200, and

then places a new call in the PSW access network 110. The management

application server 250 then instructs the other party to the call to establish a

new connection via the media gateway 260 (e.g., using third party call

control issuing a "re-invite"). Once this call is established, the original CSW

call from the multimode wireless subscriber 10 is terminated.

Claims

What is claimed is:

1. A telecommunications system for wireless subscribers, comprising:

circuit-switched and packet-switched wireless access networks;

at least one multimode wireless subscriber comprising means for

placing and receiving calls through the circuit-switched and packet-switched

wireless access networks; and

a supervisory network comprising means for managing calls placed

and received by the multimode wireless subscriber through the

circuit-switched and packet-switched wireless access networks.

2. A telecommunications system as set forth in claim 1, where the

supervisory network comprises an IP Multimedia Subsystem.

3. A telecommunications system as set forth in claim 1, where the

means for managing calls comprises a management application server

comprising an interface between the supervisory network and the

circuit-switched wireless access network.

4. A telecommunications system as set forth in claim 3, where the

interface comprises means for converting subscriber-signaling information

from a format of an ISC (IP multimedia subsystem Service Control interface) to MAP (Mobile Application Part) protocol, and from MAP

protocol to the format of the ISC.

5. A telecommunications system as set forth in claim 1, where the

means for managing calls comprises means for providing notification of the

registration of the multimode wireless subscriber attaching to a packet-

switched wireless access network to a circuit-switched wireless access

network.

6. A telecommunications system as set forth in claim 5, where the

means for providing notification comprises a management application server

comprising an interface between the supervisory network and the circuit-

switched wireless access network.

7. A telecommunications system as set forth in claim 6, where the

interface comprises means for converting subscriber-signaling information

from a format of an ISC (IP multimedia subsystem Service Control

interface) to MAP (Mobile Application Part) protocol, and from MAP

protocol to the format of the ISC.

8. A telecommunications system as set forth in claim 1, where the

means for managing calls comprises means for recording the registration of the multimode wireless subscriber attaching to a circuit-switched wireless

access network.

9. A telecommunications system as set forth in claim 8, where the

means for recording the registration of the multimode wireless subscriber

attaching to a circuit-switched wireless access network comprises a

management application server comprising an interface between the

supervisory network and the circuit-switched wireless access network.

10. A telecommunications system as set forth in claim 8, where the

means for recording the registration of the multimode wireless subscriber

attaching to a circuit-switched wireless access network further comprises

means for recording the detachment of the multimode wireless subscriber

from the circuit-switched wireless access network.

11. A telecommunications system as set forth in claim 10, where the

means for recording the registration of the multimode wireless subscriber

detaching from a circuit-switched wireless access network comprises a

management application server comprising an interface between the

supervisory network and the circuit-switched wireless access network.

12. A telecommunications system as set forth in claim 1, where the

means for managing calls comprises means for managing call features for

the multimode wireless subscriber attached to either a circuit-switched or a

packet-switched wireless access network.

13. A telecommunications system as set forth in claim 12, where the

means for managing call features comprises:

a voice application server; or

a combination of a voice application server and a home

subscriber server.

14. A telecommunications system as set forth in claim 12, where the

means for managing call features comprises means for routing a call placed

or received by the multimode wireless subscriber in the circuit-switched

wireless access network to the supervisory network.

15. A telecommunications system as set forth in claim 14, where the

means for routing a call placed or received by the multimode wireless

subscriber in the circuit-switched wireless access network comprises means

for detecting an intelligent network trigger or a predetermined prefix

assigned to the subscriber.

16. A telecommunications system as set forth in claim 14, where the

means for managing call features comprises:

a voice application server; or

a combination of a voice application server and a home

subscriber server.

17. A telecommunications system as set forth in claim 12, where the

means for managing call features comprises at least one means for

implementing a call feature for a call placed or received by a multimode

wireless subscriber attached to either a circuit-switched or a packet-switched

wireless access network.

18. A telecommunications system as set forth in claim 18, where the

means for implementing a call feature comprises a voice application server.

19. A telecommunications system as set forth in claim 1, where the

means for managing calls comprises:

means for registering the attachment of the multimode wireless

subscriber to a first wireless access network; and

means for detecting the attachment of the multimode wireless

subscriber to a second wireless access network.

20. A telecommunications system as set forth in claim 20, where the

means for registering the attachment of a multimode wireless subscriber to a

first wireless access network and the means for detecting the attachment of

the multimode wireless subscriber to a second wireless access network

comprise a management application server.

21. A telecommunications system as set forth in claim 20, further

comprising means for recording the attachment of the multimode wireless

subscriber to a second wireless access network.

22. A telecommunications system as set forth in claim 22, where

the second wireless access network is a circuit-switched wireless

access network; and the means for recording the attachment of the multimode wireless

subscriber to a second wireless access network is a management application

server.

23. A telecommunications system as set forth in claim 20, further

comprising:

means for detecting the presence of a call in progress between the

multimode wireless subscriber and at least one other party;

means for re-inviting the other party to re-establish the call through

the second wireless access network; and

means for terminating the call through the first wireless

access network.

24. A telecommunications system as set forth in claim 24, where the

means for re-inviting the other party to re-establish the call through the

second wireless access network and the means for terminating the call

through the first wireless access network comprise a management

application server.

25. A management application server for a supervisory network for a

telecommunications system for multimode wireless subscribers comprising

circuit-switched and packet-switched wireless access networks, and at least one multimode wireless subscriber comprising means for placing and

receiving calls through circuit-switched and packet-switched wireless access

networks, comprising:

means for controlling roaming of a multimode wireless subscriber

between circuit-switched and packet-switched wireless access networks.

26. A management application server as set forth in claim 26, further

comprising an interface between the supervisory network and the

circuit-switched wireless access network.

27. A management application server as set forth in claim 27, where the

interface comprises means for converting subscriber-signaling information

from a format of an ISC (IP multimedia subsystem Service Control

interface) to MAP (Mobile Application Part) protocol, and from MAP

protocol to the format of the ISC.

28. A management application server as set forth in claim 26, where the

means for controlling comprises means for controlling handover of a call

placed or received by a multimode wireless subscriber from

a circuit-switched wireless access network to a packet-switched

wireless access network; or

from a packet-switched wireless access network to a circuit-switched

wireless access network.

29. A management application server as set forth in claim 29, where the

means for controlling comprises means for converting subscriber-signaling

information from a format of an ISC (IP multimedia subsystem Service

Control interface) to MAP (Mobile Application Part) protocol, and from

MAP protocol to the format of the ISC.

30. A method for managing a telecommunications system for multimode

wireless subscribers, comprising circuit-switched and packet-switched

wireless access networks, at least one multimode wireless subscriber

comprising means for placing and receiving calls through circuit-switched

and packet-switched wireless access networks, and a supervisory network,

comprising:

routing calls placed and received by the multimode wireless subscriber

through the circuit-switched and packet-switched wireless access networks

to the supervisory network; and

managing the calls within the supervisory network.

31. A method for managing a telecommunications system as set forth in

claim 31, where the step of managing the calls comprises: recording

the registration of the multimode wireless subscriber attaching to a packet-

switched wireless access network; andproviding notification of the

registration of the multimode wireless subscriber attaching to a packet-

switched wireless access network to a circuit-switched wireless access

network.

32. A method for managing a telecommunications system as set forth in

claim 32, further comprising recording the detachment of the multimode

wireless subscriber from the packet-switched wireless access network.

33. A method for managing a telecommunications system as set forth in

claim 31, where the step of managing the calls comprises:

managing call features, from within the supervisory network, for a

multimode wireless subscriber attached to either a circuit-switched or a

packet-switched wireless access network; and

implementing a call feature, from within the supervisory network, for

a multimode wireless subscriber attached to either a circuit-switched or a

packet-switched wireless access network.

34. A method for managing a telecommunications system as set forth in

claim 31, where the step of managing the calls comprises:

registering the attachment of the multimode wireless subscriber to a

first wireless access network; and

detecting the attachment of the multimode wireless subscriber to a

second wireless access network.

35. A method for managing a telecommunications system as set forth in

claim 35, further comprising recording the attachment of the multimode

wireless subscriber to a second wireless access network.

36. A method for managing a telecommunications system as set forth in

claim 35, further comprising:

detecting the presence of a call in progress between the multimode

wireless subscriber and at least one other party;

re-inviting the other party to re-establish the call through the second

wireless access network; and

terminating the call through the first wireless access network.