WO2013024054A1

WO2013024054A1 - Method and a system for identification of bearers in a mobile communication network

Info

Publication number: WO2013024054A1
Application number: PCT/EP2012/065752
Authority: WO
Inventors: Gottfried Punz; Andreas Kunz
Original assignee: Nec Europe Ltd.
Priority date: 2011-08-12
Filing date: 2012-08-10
Publication date: 2013-02-21

Abstract

The present invention relates to a method for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile network, comprising the steps of a) Establishing a session inducting at least one bearer between a user equipment and a core network entity b) Identifying at least one of the bearers for performing an action on this at least one bearer, c) Informing the user equipment about the identified bearer. The invention also relates to a system for identification of bearers in a mobile communication network.

Description

METHOD AND A SYSTEM FOR IDENTIFICATION OF BEARERS IN A MOBILE COMMUNICATION NETWORK

The invention relates to a method for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile communication network.

The present invention also relates to a system for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile network, comprising a user equipment and at least one core network entity, preferably a mobility management entity.

Although applicable to any bearers defined or established between a user equipment and a core network entity, the present invention will be described with regard to bearers in the packet switched domain according the 3^rd Generation Partnership Project 3GPP.

In release 1 1 of the 3^rd Generation Partnership Project 3GPP a so-called Single Radio Video Call Continuity vSRVCC is described. By the use of the Single Radio Video Call Continuity a handover of an IP Multimedia Subsystem voice and video session from an Evolved Universal Terrestrial Radio Access Network E-UTRAN to a Universal Terrestrial Radio Access Network UTRAN is enabled as well as a conversion of the packet switched voice and video session into a circuit switched video call. However a user equipment does not recognize which of the packet switched bearers of the voice and video session are part of the Single Radio Video Call Continuity handover and will be further moved to the circuit switched domain. Video media maybe included in any of the packet switched bearers; therefore a handover of an IP multimedia subsystem voice and video session to the Universal Terrestrial Radio Access Network might fail.

It is therefore an objective of the present invention to provide a simple and flexible method and system enabling a recognition of bearers for an action. It is a further objective of the present invention to provide a method and a system for identification of bearers in a mobile communication network enabling a provision of bearer properties in addition to well defined end-to-end bearer properties like quality of service (QoS) or filters.

The aforementioned objectives are accomplished by a method of Claim 1 and a system of Claim 13.

According to Claim 1 the method for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile network is characterized by the steps of

a) Establishing at least one bearer between a user equipment and a core network entity

b) Identifying at least one of the bearers for performing an action on this at least one bearer,

c) Informing the user equipment about the identified bearer.

According to Claim 13 the system for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile network, comprising a user equipment, and at least one core network entity, preferably a mobility management entity.

According to Claim 13 the system characterized in that the user equipment and the at least one core network entity are configured to be operable to establish at least one bearer between the user equipment and at least one core network entity, that an identifying core network entity is configured to be operable to identify at least one of the bearers for performing an action on this at least one bearer, and that the identifying core network entity is configured to be operable to inform the user equipment about the identified bearer.

According to the invention it has first been recognized that a dynamical "marking" of bearers in Evolved Packet System or PDP contexts in GPRS is provided by informing the user equipment about identified bearers. According to the invention it has first been recognized that the method and the system for identification of bearers is more flexible since for example an indication of bearers/PDP contexts being candidates for packet switched to circuit switched session continuity is enabled.

Further features, advantages and preferred embodiments are described in the following subclaims.

According to a preferred embodiment a core network entity performs step c) preferably in form of a mobility management entity. One of the advantages by informing the user equipment from their network side is, that this enables a very simple and lightweight as well as reliable information of the user equipment about the identified bearer. According to a further preferred embodiment, step b) and/or step c) are performed during step a). This enables a very fast identification of bearers in the mobile communication network, providing a high quality of experience for a user of the user equipment. According to a further preferred embodiment step c) is performed by sending an information message including identified bearer information. This provides a simple and lightweight way to inform the user equipment about the identified bearers. According to a further preferred embodiment an existing signaling message of the mobile communication network is used as session management information message with added identified bearer information. This allows a reuse of existing messages and therefore an easy way to inform the user equipment about the identified bearer(s) without the need to introduce a new type of message exchange between the involved mobile communication network components.

According to a further preferred embodiment the existing message is an EMM, GMM or ESM notification message. This provides dependent on the involved mobile communication network best suited messages sent from the core network to the user equipment unacknowledged. In case of a mobile communication network of type GPRS the GPRS mobility management GMM information message could be used. Further in an evolved packet system EPS an EPS session management message ESM could also be used.

According to a further preferred embodiment an information element is added in the content of the session management information message representing identified bearer information. Such information elements maybe "EPS bearer context status" in an involved packet system EPS or "PDP context status" in a GPRS network or "EPS bearer identity". This allows in a very simple and "noninvasive" way to inform the user equipment about the identified bearer.

According to a further preferred embodiment the identification of the bearer according to step b) is dependent on network and/or bearer conditions, preferably a network overload, network congestion and/or bearer degradation. If for example the identification of the bearer according to step b) is dependent on network conditions, the user equipment may consider application related means against a degradation of the bearer, allowing an enhanced quality of experience for a user. According to a further preferred embodiment in a further step d) the action is performed on the identified bearer. This enables performing the action on the identified at least one bearer.

According to a further preferred embodiment executing step d) is dependent on a fulfilled predefined network operator trigger condition which is preferably location based. This enables to perform the action on the bearer when the user equipment for example enters a wireless local area network hotspot or a certain area so that for example connections to the Internet are established via the wireless local area network and not via the mobile communication network providing a user a faster and in general cheaper connection of his user equipment to the internet. The trigger could be based on network conditions, for example overload situations in the mobile communication network. According to a further preferred embodiment step c) is performed after the network operation trigger condition is fulfilled. One of the advantages is that information exchange between the core network and the user equipment is reduced thus saving resources.

According to a further preferred embodiment step c) is performed prior to a fulfilled network operation trigger condition. One of the advantages is that the user equipment gets unformed prior to a fulfilled trigger condition thus time for executing of step d) is reduced. This further enhances the Quality of Experience (QoE) for users.

There are several ways how to design and further develop the teaching of the present invention in an advantageous way. To this end, it is to be referred to the patent claims subordinate to patent claim 1 on the one hand and to the following explanation of preferred examples of embodiments of the invention, illustrated by the drawing on the other hand. In connection with the explanation of the preferred embodiments of the invention by the aid of the drawing, generally preferred embodiments and further developments of the teaching will we explained.

In the drawings

Fig. 1 shows bearer paths between a user equipment and a core network before a vSRVCC handover according to a first embodiment of the present invention.

Fig. 2 shows bearer paths after vSRVCC handover according to Fig.

1 ;

Fig. 3 shows bearer paths of three video sessions before a vSRVCC handover similar to Fig. 1 according to a second embodiment of the present invention;

Fig. 4 shows a method according to a third embodiment of the present invention; Fig. 5 shows a signaling flow for a vSRVCC handover according to a fourth embodiment of the present invention;

Fig. 6 shows a bearer identification for offload according to a fifth embodiment of the present invention;

Fig. 7 shows a method according to a sixth embodiment of the present invention;

Fig. 8 shows a method according to a seventh embodiment of the present invention; and

Fig. 9 shows a method according to an eighth embodiment of the present invention.

In Fig. 1 bearer paths between the user equipment and the core network before the vSRVCC handover are shown. A user equipment UE comprising an interface 1 establishes 3 bearers, B1 , B2, B3 via an access system AS1 to the network domain CN1 in the core network CN of the mobile communication network. The user equipment UE and the access system AS1 are part of the radio access network RAN. The interface 1 is according to Fig. 1 an LTE interface. The access system AS1 is an evolved Node B eNB and the network domain CN1 is E-UTRAN. To move a video session from E-UTRAN to UTRAN the corresponding packet switched session comprising the three bearers B1 , B2, B3 is converted into a circuit switched video call. For this reason at least one voice bearer with the quality of service class indicator QCI=1 and one of the bearers B1 , B2, B3 being a video bearer must exist. Since there is no binding of the Quality of Service class indicator to the video session (as it is provided for the voice session) it is not possible for the user equipment UE to recognize, in which bearer B1 , B2, B3 the video data is located. The user equipment UE could have multiple bearers and a bearer marking for the video is done only up to the core network entity in form of the mobility management entity in the context of the dedicated bearer setup procedure, where the policy-and-charging-rules-function PCRF receives the session description information from the application function AF or from the traffic detection function TDF, and creates rules accordingly.

In Fig. 1 the user equipment has 3 bearers B1 , B2, B3: The general packet switched bearer B1 , one bearer B2 for voice data and one bearer B3 for video data. The user equipment UE needs therefore to be aware that the video is included in the third bearer B3. According to vSRVCC the second and the third bearer B2, B3 are moved to the circuit switched domain in the UMTS Terrestrial Radio Access Network UTRAN. The bearers B2, B3 are therefore not anymore in the packet switched domain. Since the user equipment UE recognizes that the voice bearer B2 with QCI=1 is gone, it does not recognize in which of the bearers B1 , B2, B3 the video data is inside and the user equipment UE would expect that the third bearer B3 is also moved to the packet switched domain of UTRAN. For this reason the user equipment UE needs to be aware that the video data in the third bearer B3 is also moved to the circuit switched domain.

Fig. 2 shows bearer paths after vSRVCC handover according to Fig. 1 .

In Fig. 2 the situation after the vSRVCC handover is shown. The first bearer B1 is moved to a second interface 2 providing UTRAN packet switched domain whereas the second and third bearer B2, B3 are moved to the UTRAN circuit switched domain of interface 3. The interfaces 1 , 2, 3 of the user equipment UE are related to corresponding network domains CN1 , CN2 and CN3. Interface 1 is a LTE interface, interface 2 is an UMTS packet switched interface and interface 3 is an UMTS circuit switched interface. The access system AS1 comprises an evolved NodeB eNB whereas the access system AS2 comprises a NodeB. The network domain CN1 is an E-UTRAN, the network domain CN2 is packet switched UTRAN and the network domain CN3 is a circuit switched UTRAN. After the vSRVCC handover the first bearer B1 is moved to the UTRAN packet switched domain and the second and third bearer B2, B3 are moved to the circuit switched UTRAN domain. If the user equipment UE would not recognize that the third bearer B3 is also moved to the circuit switched UTRAN domain, it will expect that the bearer respectively the corresponding session would get continued over the packet switched domain in UTRAN. However, this is not the case. From the two expected packet switched bearers B1 , B3 the user equipment UE will receive only one, namely the first bearer B1 . A corresponding application is affected since the user equipment UE would assume that the video was terminated by the core network CN during the handover.

Fig. 3 shows bearer paths of three video sessions before a vSRVCC handover similar to Fig. 1 according to a second embodiment of the present invention. In Fig. 3 bearer paths of three different video sessions before the vSRVCC handover are shown. This is the case, if the user equipment UE has one or more voice and video sessions at the same time, for example when video conferencing is performed on the user equipment UE. The core network CN then decides which video and voice sessions are to be transferred to the circuit switched domain. According to 3GPP TS 23.237 and 3GPP TS 23.216 the latest active voice and video session is selected for the transfer and all other voice and video sessions are terminated.

In Fig. 3 the first bearer B1 is the default bearer. Bearers B2, B4 and B6 correspond to speech media and bearers B3, B5 and B7 correspond to video media. In case the latest active voice and video session is the one in the second and third bearer B2, B3 then the resulting bearers B4, B5, B6, B7 after the vSRVCC handover are accordingly switched to the circuit switched domain in correspondence with Fig. 2. The user equipment UE in this case needs to know that the bearers B3, B5 and B7 will be terminated and not continued over packet switched domain.

In the following Fig. 4 a method according to third embodiment of the present invention is shown. Fig. 4 shows an option of providing the information of the candidate video bearers for example for switching after dedicated bearer setup procedure described in 3GPP TS 23.401 , clause 5.4.1 . After the dedicated bearer activation procedure in a first step S1 is performed between a user equipment UE, a mobility management entity MME and a serving gateway SGW, respectively a packet data network gateway PGW, the mobility management entity MME sends in a second step S2 EMM information to the user equipment UE. With the message according to the second step S2, namely the EMM information message the user equipment UE gets instructed which bearers are candidates of the vSRVCC handover. It is also possible to send already the EMM information message during the dedicated bearer activation procedure according to the first step as 1 , preferably after the mobility management entity MME receives a bearer setup response according to 3GPP TS 23.401 , clause 5.4.1 -1 , step 7. Fig. 5 shows a signaling flow for a vSRVCC handover according to a forth embodiment of the present invention.

In Fig. 5 a detailed vSRVCC handover procedure is shown including a new step S4a-12a where the EMM information message including identified bearer information is sent to the user equipment UE. This new step S4a-12a should be performed preferably after the forth step 4 of bearer splitting and before the handover command of step 13 is sent. The EMM information message is sent from the source mobility management entity to the user equipment UE. All other steps shown in Fig. 5 are conventional steps according to 3GPP TS 23.216, clause 6.2.2.3.

Fig. 6 shows a bearer identification for offload according to a fifth embodiment of the present invention. In Fig. 6 a bearer identification for hinting on offload preference is shown. In Fig. 6 the information about an identified bearer is used for offloading that identified bearer, for example when the mobile communication network runs into an overload situation. After the user equipment UE, the mobility management entity MME and the serving gateway SGW/packet data network gateway PGW have established a packet switched bearer session via 3GPP access in a first step S1 , the mobility management entity MME identifies bearers for a potential offload and sends corresponding information included in an EMM information message to the user equipment UE in a second step S2. Therefore after normal bearer establishment in the first step S1 the mobility management entity MME signals the user equipment UE in the EMM information message which bearers are candidates for offload, for example to a non-3GPP access e.g. a wireless local area network if available and if the user equipment UE is capable of connecting to it.

When the user equipment UE gets triggered, for example by an operator defined trigger based on network conditions, e.g. by the mobility management entity MME or the serving gateway SGW/packet data network gateway PGW, in a third step S3 the user equipment UE starts in a fourth step S4 the access transfer and moves the corresponding bearers that are marked in the EMM information message to the non-3GPP access. The operator defined trigger according to step S3 could be location based, for example when the user equipment UE enters a wireless local area network WLAN hotspot or a certain area or it can be based on network conditions, for example overload situations by any other mobile network operator policy which is recognized by or communicated to the user equipment UE.

Fig. 7 shows a method according to a sixth embodiment of the present invention. In Fig. 7 corresponding steps S1 - S4 of Fig. 6 are shown. However, the EMM information message is sent in a third step S3 after an operator defined trigger is recognized in a second step S2. In Fig. 7 the mobility management entity MME recognizes the operator defined trigger in the second step S2 and informs then the user equipment UE in a third step S3 to indicate to the user equipment UE which of the bearers should be moved to non-3GPP access in a fourth step S4.

Fig. 8 shows a method according to a seventh embodiment of the present invention. In Fig. 8 a similar procedure according to the Figs. 6 and 7 is shown. After a conventional packet switched bearer setup via 3GPP access between the user equipment UE, the mobility management entity MME and the Serving Gateway SGW/packet data network gateway PGW the mobility management entity MME decides in a first step S1 which bearers are subject to a bearer degradation, in case for example of a network overload. The user equipment UE is therefore informed in advance by the core network CN which bearer(s) should be offloaded if certain conditions are fulfilled. If the user equipment UE, the mobility management entity MME and/or the Serving Gateway SGW/packet data network gateway PGW detects in a third step S3 an overload, the user equipment UE or an entity in the core network, in particular the mobility management entity MME or the serving gateway SGW/packet data network gateway PGW starts a corresponding bearer modification procedure for the bearers that are marked in the EMM information message according to step S2 to degrade them according to the new situation in a fourth step S4.

Fig. 9 shows a method according to an eighth embodiment of the present invention. Fig. 9 shows a triggering of a user equipment UE to perform an action directly with a EMM information message once the mobility management entity MME detects an overload situation in the network or gets triggered by any other operator defined trigger. Fig. 9 is therefore similar to Fig. 8 with steps S2 and S3 swapped. When the mobility management entity MME detects a network overload in a second step S2 the mobility management entity MME informs the user equipment UE in a third step S3 by sending an EMM information message to the user equipment UE about the detected overload as well as about the identified bearers for degradation. The user equipment UE, the mobility management entity MME and/or the serving gateway SGW/packet data network gateway PGW then start a bearer modification procedure for the bearers that are marked in the EMM information message to degrade them according to the new situation.

In the following a detailed coding on the protocol level in an evolved packet system EPS of an EMM information message according to 3GPP TS 24.301 is shown and extended for the purposes to include information about identified bearers. Such a coded EMM information message may be used in particular in the Fig. 4 to 9. In GPRS, a corresponding extension is made in the GMM information message according to 3GPP TS 23.008. The coding of the EMM information message maybe then as follows:

Table 1 : EMM INFORMATION message content

A new information element "extended EPS bearer context status" is introduced and maybe described in principal as follows:

A "Reason" maybe included and represented by a 1 octet field. "Reasons" as given in the embodiments of the Figs. 4 to 9 may be a) "PS-to-CS-continued"

This information element may be sent by a network entity. If this information element is sent, the contents of this information element indicates the bearers which are to be continued in the circuit switched domain CS after SRVCC handover. Once the user equipment UE received the EMM INFORMATION message, it can interpret the following handover command HO COMMAND in the right way, so that it can remove the corresponding packet switched bearers in the user equipment.

b) Offload preference"

This information element may be sent by a network entity. If this information element is sent, the contents of this information element indicate the bearers which are preferred by the network to be offloaded from the 3GPP domain. The user equipment UE will start access transfer for those bearers once it gets triggered.

c) "Degradation possible"

This information element may be sent by a network entity. If this information element is sent, the contents of this information element indicate the bearers for which degradation is deemed imminent by the network. The user equipment UE uses this information once it gets triggered to do a user equipment requested bearer resource modification or, in case of network initiated bearer modification, the user equipment UE is prepared and can take action accordingly on application layer e.g. start codec changes early for smooth user experience.

Further, the "EPS bearer context status" may be 4 octet field according to 3GPP TS 24.301 , subclause 9.9.2.1 .

In summary the present invention enables signaling of bearers that are part of a vSRVCC handover to the user equipment within a non-access stratum NAS message. The present invention further enables a signaling of candidate bearers for offload and a signaling of candidate bearers that could be subject of bearer degradation. One of the advantages of the present invention is that it enables video SRVCC. Another advantage is that the present invention provides a lightweight method and system for signaling bearer related information to the user equipment. Many modifications and other embodiments of the invention set forth herein will come to mind the one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

The EMM INFORMATION message can be replaced with any other message sent from the core network to the user equipment, for example ESM NOTIFICATION message from the mobility management entity to the user equipment.

Claims

C l a i m s

A method for identification of bearers (B1 , B2, B3, B4, B5, B6, B7) in a mobile communication network (RAN, CN), preferably in form of a LTE, UMTS or GPRS mobile network, characterized by the steps of

a) Establishing a session inducting at least one bearer (B1 , B2, B3, B4, B5, B6, B7) between a user equipment (UE) and a core network entity (CN, CN1 , CN2, CN3)

b) Identifying at least one of the bearers (B1 , B2, B3, B4, B5, B6, B7) for performing an action on this at least one bearer (B1 , B2, B3, B4, B5, B6, B7),

c) Informing the user equipment (UE) about the identified bearer (B1 , B2, B3, B4, B5, B6, B7).

The method according to claim 1 , characterized in that a core network entity (MME) performs step c), preferably in form of a mobility management entity.

The method according to one of the claims 1 -2, characterized in that step b) and/or step c) are performed during step a).

The method according to one of the claims 1-3, characterized in that step c) is performed by sending (S2; S3; S4a-12a) an session management information message including identified bearer information.

The method according to claim 4, characterized in that an existing signaling message of the mobile communication network (RAN, CN) is used as session management information message with added identified bearer information.

The method according to claim 5, characterized in that the existing message is an EMM, GMM or ESM notification message.

7. The method according to one of the claims 4-6, characterized in that an information element (IE) is added in the content of the session management information message representing identified bearer information. 8. The method according to one of the claims 1 -7 characterized in that the identification of the bearer according to step b) is dependent of network and/or bearer conditions, preferably a network overload, network congestion and/or bearer degradation.

9. The method according to one of the claims 1 -8, characterized in that in a further step d) the action is performed on the identified bearer (B1 , B2, B3, B4, B5, B6, B7).

10. The method according to one of the claims 1 -9, characterized in that executing step d) is dependent on a fulfilled predefined network operator trigger condition which is preferably location based.

1 1. The method according to claims 9 and 10, characterized in that after the network operation trigger condition is fulfilled, step c) is performed.

12. The method according to claims 9 and 1 1 , characterized in that step c) is performed prior to a fulfilled network operation trigger condition.

13. A system for identification of bearers in a mobile communication network, preferably in form of a LTE, UMTS or GPRS mobile network, comprising a user equipment (UE), and

at least one core network entity (CN), preferably a mobility management entity (MME),

characterized in that

the user equipment (UE) and the at least one core network entity (CN) are configured to be operable to establish at least one bearer (B1 , B2, B3, B4, B5, B6, B7) between the user equipment (UE) and the at least one core network entity (CN), that an identifying core network entity (MME) is configured to be operable to identify at least one of the bearers (B1 , B2, B3, B4, B5, B6, B7) for performing an action on this at least one bearer (B1 , B2, B3, B4, B5, B6, B7), and that

the identifying core network entity (MME) is configured to be operable to inform the user equipment (UE) about the identified bearer (B1 , B2, B3, B4, B5, B6, B7).