WO2008096258A1

WO2008096258A1 - A system and method for dynamic bearer allocation

Info

Publication number: WO2008096258A1
Application number: PCT/IB2008/000291
Authority: WO
Inventors: Lars Gunnar Lovsen; Gunnar Rydnell; Hans Bertil Ronneke; Stefan Karl Toth
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2007-02-09
Filing date: 2008-02-08
Publication date: 2008-08-14

Abstract

A system and method of allocating bearers in a telecommunications system. The system and method enable the integration of multicast bearers with unicast bearers. In the method of allocating bearers, a unit equipment (UE) requests a service to a telecommunications system. Next, a type of bearer associated with the requested service is determined. The type of bearer may be either be a multicast or a unicast bearer. The determined type of bearer is then allocated for the requested service by the UE.

Description

A SYSTEM AND METHOD FOR DYNAMIC BEARER ALLOCATION

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to communications networks, and in particular, to communications networks that employ methods and systems for dynamically allocating bearers in a telecommunications network.

DESCRIPTION OF RELATED ART

In current mobile communications systems, such as the 3^rd Generation Partnership Project (3GPP) based systems, signaling is based on associating a bearer (a logical and/or physical communications channel for communicating information between points). Bearers are utilized on several levels. There is a physical radio bearer service between a mobile terminal (MT) and a Radio Access Network (RAN) and a physical bearer server between the RAN and a Core Network (CN) node, such as a Serving GPRS Support Node (SGSN). In addition, there is a radio bearer service between the MT and the RAN, and an access bearer service between the RAN and the SGSN. A backbone bearer service is also located between the SGSN and a CN gateway, such as a Gateway GPRS Support Node (GGSN). There is also a radio bearer service between the RAN and the SGSN. A Radio Access Bearer (RAB) service extends between the MT and SGSN, and a backbone bearer service extends between the SGSN and the GGSN.

IP Multimedia Subsystem (IMS) is a technology which is defined by the 3GPP to provide IP Multimedia services over 3G mobile communication networks. IMS provides key features to enrich the end-user person-to-person communication experience through the integration and interaction of services. IMS allows rich person-to-person (client-to-server) communications over an IP- based network.

In GPRS, there also exists a Multimedia Broadcast/Multicast Service (MBMS) for efficient distribution of a service to a large number of users using GPRS specific multicast distribution. However, currently, the MBMS and the IMS services are not integrated in any way. It would be advantageous to have a system and method which integrates IMS and MBMS services and an enhanced function for delivery of payload in the Packet Switched (PS) core network. The present invention provides such a system and method.

SUMMARY OF THE INVENTION

The present invention is a system and method of allocating bearers in a telecommunications system. The system and method enable the integrated use of multicast bearers with unicast bearers. In one aspect, the invention is directed to a method of allocating bearers. The method begins by a unit equipment (UE) requesting a service to a telecommunications system. Next, a type of bearer associated with the requested service is determined. The type of bearer may be either a multicast or a unicast bearer. The determined type of bearer is then allocated for the requested service by the UE.

In another aspect, the present invention is a system for allocating bearers in a telecommunications system. The system includes at least one unit equipment (UE) initiating a service request in a telecommunications system. A type of bearer associated with the requested service is then determined. The type of bearer may be either a multicast or a unicast bearer. The determined type of bearer is then allocated for the requested service by the UE.

In still another aspect, the present invention is a decision node for allocating bearers in a telecommunications system. The decision node includes a function for determining a type of bearer associated with a requested service received from a unit equipment operation in a telecommunications system. The type of bearer may be either a multicast or a unicast bearer. The decision node also includes a function for allocating the determined type of bearer for the requested service by the UE in the telecommunications system.

In another aspect, the present direction is directed to a method of dynamically allocating bearers during a session in a telecommunications system. The method begins by determining that a service provided during a session by a plurality of users of the telecommunications system is optimized by changing a type of bearer associated with the service. The type of bearer may either be a unicast bearer or a multicast bearer. Next, a new type of bearer different from a currently used type of bearer is allocated for the service. Users of the service are then signaled to use the allocated new type of bearer. The currently used type of bearer is then removed for use by the service.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 (prior art) is an existing simplified block diagram of a 3GPP MBMS architecture;

FIG. 2 is a simplified block diagram of a system splitting a BM-SC into a user part and a bearer related part according to an embodiment of the present invention;

FIG. 3 illustrates a simplified block diagram of an IMS-MBMS bearer use in a preferred embodiment of the present invention;

FIG. 4 is a flow chart illustrating the steps of bearer selection according to the teachings of the present invention; and

FIG. 5 is a flow chart illustrating the steps of reallocating multicast bearers during a session in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention is a system and method of dynamically allocating bearers in a telecommunications system. FIG. 1 is an existing simplified block diagram of a 3GPP MBMS architecture. The MBMS architecture includes a network 10 having a broadcast/multicast service center (BM-SC) 12 communicating with a GGSN 14. The BM-SC is a collection of MBMS user functions and MBMS bearer functions. The GGSN then communicates through one or more SGSNs 16 to RANs 20, 22, 24, and 26. In turn, services are provided to end users (not shown). In the MBMS architecture, typically a GPRS Tunneling Protocol (GTP) is utilized. In this current architecture, the MBMS and the IMS services are not integrated.

FIG. 2 is a simplified block diagram of a system 100 splitting a BM-SC into a user part and a bearer related part. The system includes a GGSN 102 having an interface G_n 104. The GGSN communicates with a BM-SC 106 through an interface G_mb 108. The GGSN also communicates with a Policy and Charging Rules Function (PCRF) 110 through an interface G_x 112. The PCRF communicates with an IMS Proxy Call Session Control Function (P- CSCF) 114 through an interface R_x 116.

The BM-SC 106 is split into a BM-SC user service 120 and a BM-SC bearer service 122. The user service performs similar functions to IMS Application Function (AF) functionality. The BM-SC bearer service 122 performs functions similar to those performed by an existing PCRF. The user service may be integrated into the IMS AF functionality, while the BM-SC bearer is integrated with the PCRF. The AF function provides user service related functions. The PCRF/MBMS bearer service provides bearer related functions, such as bearer activation.

FIG. 3 illustrates a simplified block diagram of an IMS-MBMS bearer use in a preferred embodiment of the present invention. A Terrestrial Radio Access Network (UTRAN) 150 communicates with a SGSN 152 through an interface l_u 154. A GSM/EDGE Radio Access Network (GERAN) 156 communicates with the SGSN 152 through an interface G_b 160. The SGSN communicates with the GGSN 102 through the G_n interface 104. The PCRF 110, having the MB-SC bearer service communicates with the GGSN through the G_mb interface 108 and G_x interface 112. The GGSN also communicates with a media resource function (MRF) 162 through an interface G₁ 164. A unit equipment (UE) 166 initiates a service request to the P-CSCF 114. The P-CSCF communicates with the PCRF through the interface R_x 116. The P-CSCF includes an IMS application server (AS) and BM-SC user service functionality 170.

With reference to FIG. 3, the operation of the system will now be explained. First, the UE 166 initiates a service request to the IMS AF (P-CSCF 114) by (session initiation protocol) SIP. Next, the P-CSCF sends a request for a bearer to the PCRF 110. The PCRF then makes a decision about bearer quality of service (QOS), etc. including utilization of unicast/multicast bearers. In particular, the PCRF makes a decision of whether the bearer is unicast or multicast. The chosen service is dependent upon the momentary user situation. If a service is foreseen to have many users using a download service in one geographic area (e.g., downloading a file at the same time), a broadcast bearer may be advantageous. For example, such a service may be an arena application, where many users subscribe to goal downloads during a football match. It may also be that the momentary user situation may influence the bearer choice, e.g., a roaming user may use an application which is usually used as a broadcast application, but due to the roaming of the user, the user may be geographically isolated and the choice of a unicast bear may be better.

The PCRF requests bearer capability from the GGSN 102. The GGSN sends a network requested secondary PDP context activation (NRSPCAO/unicast/multicast mode indicators; IP MC Address) request to the UE 166. The UE then initiates secondary packet data protocol (PDP) extension or MBMS UE connection bearer establishment.

FIG. 4 is a flow chart illustrating the steps of bearer selection according to the teachings of the present invention. With reference to FIGs.3 and 4, the method will now be explained. The method begins in step 200 where a bearer selection algorithm is initiated in a decision node, such as the PCRF or the BM- SC. Next, in step 202, it is determined by the decision node if a session description protocol (SDP) multicast bearer request has been made. If it is determined that an SDP multicast bearer request has not been made, the method moves to step 204 where the decision node instructs the GGSN to start network initiated PDP activation.

However, in step 202, if it is determined by the decision node that the SDP multicast bearer request has been received, the method moves to step 206 where it is determined by the decision node if multiple users are in the same area. If it is determined that multiple users are not in the same area, the method moves to step 204 where the decision node instructs the GGSN to start network initiated PDP activation.

In step 206, if it is determined that there are multiple users in the same area, the process then moves to step 208 where the decision node determines if the user is roaming. If it is determined that the user is roaming, the method moves to step 204 where the decision node instructs the GGSN to start network initiated PDP activation. In step 208, if it is determined that the user is not roaming, the process moves to step 210 where the decision node allocates a multicast bearer and sends a start session to the GGSN.

A specific problem may arise when a service may be applicable for both unicast and broadcast bearers. The present invention may provide for the dynamic reallocation of the service during a session. For example, a group call may start out between only two users, but later during the session, other users may join. In such a situation, it is advantageous to implement a method to change the bearer of the service from unicast to broadcast and vice versa. Without explicit procedures for dynamically changing the bearer during a session, bearer type request may be signaled to the PCRF over the Rx interface.

FIG. 5 is a flow chart illustrating the steps of reallocating multicast bearers during a session in accordance with a preferred embodiment of the invention. In step 300, a decision node, such as the PCRF or the BM-SC, determines that the bearer should be changed from unicast to a multicast bearer (e.g., when a new UE is added to the session). Next, in step 302, the multicast bearer is allocated by the decision node. In step 304, a signal is sent to the new UE to use the multicast bearer. In step 306, a signal to all old UEs is sent to change to the new MC bearer. Step 308 removes the old unicast bearers. The present invention may also be utilized to change from multicast to unicast bearers as decided by the decision node.

The present invention provides the advantage of efficient utilization of radio resources. The present invention may utilized both multicast and unicast bearers for use in a telecommunications network. An efficient distribution of a service to a large number of users may be realized by using GPRS specific multicast distribution.

The present invention may of course, be carried out in other specific ways than those set forth herein without departing from the essential characteristics of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

1. A method of allocating bearers in a telecommunications system, the method comprising the steps of: requesting by a unit equipment (UE) a service to a telecommunications system; determining a type of bearer associated with the requested service, the type of bearer being a multicast or a unicast bearer; and allocating the determined type of bearer for the requested service by the UE.

2. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of requesting by a UE includes requesting a service to a IP Multimedia Subsystem (IMS) application function (AF).

3. The method of allocating bearers in a telecommunications system of claim 2 wherein the step of requesting includes using Session Initiation Protocol (SIP) signaling.

4. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of determining a type of bearer is conducted by a Policy and Charging Rules Function (PCRF) within the telecommunications system.

5. The method of allocating bearers in a telecommunications system of claim 4 wherein the PCRF provides a bearer service functionality.

6. The method of allocating bearers in a telecommunications system of claim 5 wherein the step of requesting a service includes requesting to a IP Multimedia Subsystem (IMS) application server (AS).

7. The method of allocating bearers in a telecommunications system of claim 6 wherein the IMS AS provides a user service functionality.

8. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of determining a type of bearer includes determining a bearer quality of service (QoS) for determining a type of bearer.

9. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of determining a type of bearer includes determining if the request is a multicast bearer request, and if so, determining that the type of bearer is a multicast bearer and allocating a multicast bearer for the requested service.

10. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of determining a type of bearer includes determining if multiple users using the service are located in the same area, and if so, determining that the type of bearer is a multicast bearer and allocating a multicast bearer for the requested service.

11. The method of allocating bearers in a telecommunications system of claim 1 wherein the step of determining a type of bearer includes determining if the UE is roaming, and if so, determining that the type of bearer is a unicast bearer and allocating a unicast bearer for the requested service.

12. A system for allocating bearers in a telecommunications system, the system comprising: at least one unit equipment (UE) initiating a service request in a telecommunications system; means for determining a type of bearer associated with the requested service, the type of bearer being a multicast or a unicast bearer; and means for allocating the determined type of bearer for the requested service by the UE.

13. The system for allocating bearers in a telecommunications system of claim 12 further comprising a IP Multimedia Subsystem (IMS) application function (AF) for receiving the service request.

14. The system for allocating bearers in a telecommunications system of claim 12 wherein the UE requests the service using Session Initiation Protocol (SIP) signaling.

15. The system for allocating bearers in a telecommunications system of claim 12 wherein the means for determining a type of bearer is conducted by a Policy and Charging Rules Function (PCRF) within the telecommunications system.

16. The system for allocating bearers in a telecommunications system of claim 15 wherein the PCRF provides a bearer service functionality for determining a type of bearer. f

17. The system for allocating bearers in a telecommunications system of claim 12 wherein the means of determining a type of bearer includes determining a bearer quality of service (QoS).

18. The system for allocating bearers in a telecommunications system of claim 12 further comprising a broadcast/multicast service center (BM-SC) having a bearer portion and a user portion.

19. The system for allocating bearers in a telecommunications system of claim 18 wherein the bearer portion performs functions of a Policy and Charging Rules Function (PCRF).

20. The system for allocating bearers in a telecommunications system of claim 18 wherein the user portion of the BM-SC performs functions of a Multimedia Subsystem (IMS) application function (AF).

21. A decision node for allocating bearers in a telecommunications system, the decision node comprising: means for determining a type of bearer associated with a requested service received from a unit equipment operation in a telecommunications system, the type of bearer being a multicast or a unicast bearer; and means for allocating the determined type of bearer for the requested service by the UE in the telecommunications system.

22. The decision node for allocating bearers in a telecommunications system of claim 21 wherein the decision node is a Policy and Charging Rules Function (PCRF).

23. The decision node for allocating bearers in a telecommunications system of claim 21 wherein the means for determining a type of bearer associated with a requested service includes determining a type of requested service and a momentary user situation of the telecommunications system to determine a optimized bearer type for use of the service.

24. The decision node for allocating bearers in a telecommunications system of claim 21 wherein the decision node dynamically changes types of bearers dependent upon use of a service within the telecommunications system.

25. A method of dynamically allocating bearers during a session in a telecommunications system, the method comprising the steps of: determining that a service provided during a session by a plurality of users of the telecommunications system is optimized by changing a type of bearer associated with the service, the type of bearer being either a unicast bearer or a multicast bearer; allocating a new type of bearer different from a currently used type of bearer; signaling to users of the service to use the allocated new type of bearer; and removing the currently used type of bearer.

26. The method of dynamically allocating bearers during a session of claim 25 wherein the currently used type of bearer is a unicast bearer and the new type of bearer is a multicast bearer.

27. The method of dynamically allocating bearers during a session of claim 25 wherein the currently used type of bearer is a multicast bearer and the new type of bearer is a unicast bearer.