CN101496352A - An internet protocol multimedia subsystem network element for reducing signalling overhead - Google Patents

Abstract

An Internet Protocol Multimedia Subsystem, IMS, (109) comprises a network element (115), such as Session Border Controller, which implements a Back to Back User Agent (B2BUA). A remote station (101) implements a User Agent Client (UAC) (111) which can transmit Session Interface Protocol (SIP) session negotiation requests intended for a User Agent Server (UAS) (113). The B2BUA receives the SIP session negotiation requests and evaluates a negotiation frequency criterion. Only the SIP session negotiation requests for which the negotiation frequency criterion is met are forwarded to the UAS (113).

Description

Internet protocol multimedia subsystem network element and method of operation thereof

Technical field

The present invention relates to a kind of internet protocol multimedia subsystem (IMS) network element and method of operation thereof, and especially but nonexcludability ground, relate to a kind of IMS of cell mobile communication systems.

Background technology

Internet protocol (IP) IP multimedia subsystem, IMS (IMS) provides the measured network architecture, and this network architecture has realized being used for fixing the multimedia communication with mobile telecommunication service.

The purpose of IMS not only is the service that provides new, and is to provide the Internet the current and following all services that provide.The user carries out its all services when in addition, must and leave its home network when roaming.In order to realize these targets, IMS uses the open standard IP agreement by the Internet engineering duty group (IETF) definition.Therefore, use identical agreement set up between the user between two IMS users, on IMS user and the Internet and the Internet on two users between Multimedia session.In addition, be used for service development personnel's interface also based on the IP agreement.This is that IMS makes the Internet and the true reason that merges of cellular world; It uses cellular technology to provide ubiquitous access and internet usage technology that attracting service is provided.

Usually, in data communication network, the communication behavior between terminal use's (or end user device) is made up of two parts, i.e. signaling and data.The IMS system does not have difference in this.Signaling mechanism allows the user location and initiates and the communicating by letter of other users or application.In case set up end-to-end communication, data division (being medium) just flows through network.

As any other network or computer system, IMS has Limited resources set (disposal ability, persistent storage and the network bandwidth), and IMS can utilize this resource collection to carry out its work.Each user in the system and application all consume those resources.The task of Virtual network operator is exactly to provide and manage these resources in the following manner: the terminal use receives the service level of its charges paid.In this example, user's actual purchase is the actual transmissions (and thereby produce experience) of data.Signaling moiety is essential expense; And himself can not bring income in essence.Therefore, can for Virtual network operator, will meet cost benefit more to any mechanism that the user provides the service level that is equal to still to have the signaling consumption of minimizing.

With one of matching used principle signaling mechanism of IMS network be the Session Initiation Protocol that in ietf standard RFC3261, defines.As its name suggests, SIP at first is used to initiate the session (for example, calling out) between the user.This SIP provides and makes user's (or equipment) can state that it is present on the network and can locatees and ask necessary information with other users' (or equipment) session.Session Description Protocol (SDP) is encapsulated in this Session Initiation Protocol.Use SDP, equipment can be consulted to obtain the access to the medium bandwidth with network (and target device), and this medium bandwidth can provide suitable service quality (QoS).Depend on bandwidth and processing requirements, end user device will adopt and use various Voice ﹠ Video encoder/decoders (codec) to handle its Media Stream.

Usually, when the user is in fixedly IP and connects in the access network (IP-CAN), session will be retained in identical bandwidth and the class of codec with initial negotiation during initial session foundation.Yet, in mobile IP-CAN, a side of Hu Jiaoing or moving in many ways wherein, they will experience variable radio propagation condition, and these contingent conditions may influence quality of call.Determine the upgrade or downgrade class of codec repeatedly in the continuous trade-off process of these contingent conditions requirements between call quality, bandwidth use, disposal ability and battery life.Each decision of change codec will cause end-to-end SIP (and SDP) message by the IMS network.This continuous exchange will influence the many equipment in the IMS network and obviously increase signaling consumption.

Therefore, a kind of improved system will be favourable, and especially, a kind of system that allows to increase flexibility, minimizing signaling, the expense that reduces, minimizing resource consumption, minimizing complexity and/or improve performance will be favourable.

Summary of the invention

Therefore, the present invention manages preferably individually or alleviates in combination, alleviates or eliminate above-mentioned one or more shortcoming with any.

According to a first aspect of the invention, a kind of network element that is used for internet protocol multimedia subsystem IMS is provided, this network element comprises the back-to-back user agent B2BUA, and this B2BUA is configured to: the User Agent Client UAC of the distant station of supporting from radio air interfaces receives session interface protocol SIP session negotiation request; The negotiation frequency criterion of assessment SIP session negotiation request; And only transmit the SIP session negotiation request that satisfies this negotiation frequency criterion to remote user agent server UAS.

The present invention can allow a kind of improved IMS.Especially, the equipment for from distant station to realization UAS can reduce signaling consumption.Especially, can provide filtration treatment, this filtration treatment only allows the subclass of SIP session negotiation request is forwarded to AUS.This method can allow to reduce signaling consumption and reduce resource consumption, the propagation conditions that compensation simultaneously changes.

The SIP session negotiation request can relate to the change support from the setting of the SIP session of the communication of distant station or the request of parameter.Particularly, the SIP session negotiation request can be to change the request that the SIP session is provided with, and this SIP session setting is more reliable or more insecure for the communication on the air interface.For example, the SIP session negotiation request can relate to change source code scheme, such as changing into different voice or Video Codec.

According to a further aspect in the invention, a kind of internet protocol multimedia subsystem IMS that comprises network element is provided, this network element comprises the back-to-back user agent B2BUA, and this B2BUA is configured to: the User Agent Client UAC of the distant station of supporting from radio air interfaces receives session interface protocol SIP session negotiation request; The negotiation frequency criterion of assessment SIP session negotiation request; And only transmit the SIP session negotiation request that satisfies this negotiation frequency criterion to remote user agent server UAS.

According to a further aspect in the invention, a kind of method of operation that is used for the network element of internet protocol multimedia subsystem IMS is provided, this network element comprises the back-to-back user agent B2BUA, and this method comprises by this B2BUA carries out the following step: the User Agent Client UAC of the distant station of supporting from radio air interfaces receives session interface protocol SIP session negotiation request; The negotiation frequency criterion of assessment SIP session negotiation request; And only transmit the SIP session negotiation request that satisfies this negotiation frequency criterion to remote user agent server UAS.

With reference to the embodiments described below, these and other aspects of the present invention, feature and advantage will be conspicuous and will be illustrated.

Description of drawings

To only embodiments of the invention be described with reference to the accompanying drawings by example, wherein:

Fig. 1 is the diagram that comprises the cellular communication system of some embodiments of the present invention;

Fig. 2 illustrates the example according to the SIP signaling flow of prior art;

Fig. 3 illustrates the example according to some functional blocks of the network element of some embodiments of the present invention;

Fig. 4 illustrates the example according to the SIP signaling flow of some embodiments of the present invention; And

Fig. 5 illustrates the example according to the flow chart of the method for operation of some embodiments of the present invention.

Embodiment

Following description concentrates on and can be applicable to for example embodiments of the invention of the IMS of UMTS cellular communication system, still should be appreciated that to the invention is not restricted to this application, but can for example be applied to other cellular communication systems.

Fig. 1 illustrates the example of some network elements of the UMTS cellular communication system with IMS core network.With clear, only illustrate among Fig. 1 and describe the required system element of embodiment for simplicity.

Fig. 1 illustrates first distant station 101 of communicating by letter with second distant station 103.In concrete example, this communication is voice communication, but should be appreciated that described principle can be applicable to other communications equally, such as video communication.In concrete example, this voice communication further is ip voice (VoIP) communication.

First distant station 101 is UMTS distant stations of being supported by first Radio Access Network (RAN) 105.Particularly, a RAN 105 comprises the UMTS base station of the communication on the air interface of supporting the UMTS cellular communication system.Similarly, second distant station 103 supported by the 2nd RAN 107, and the 2nd RAN 107 comprises going to and the different UMTS base station of communicating by letter from second distant station on the air interface of supporting the UMTS cellular communication system particularly.

Should be appreciated that in other examples distant station 101,103 can be supported by identical RAN, and can support by the base station of the difference (or identical) of single RAN particularly.It is also understood that described principle for example can be applicable to equally, the communication between first distant station 101 and fixed terminal (such as via the terminal that is coupled to the Internet at the gateway between UMTS cellular communication system and the Internet).

In the system of Fig. 1, RAN 105,107 is coupled by the core network that comprises IMS 109.This IMS network be based on the network of Internet protocol (IP) and in the IMS network and the communication between RAN 105,107 use this IP agreement.Especially, Session Initiation Protocol is used to initiate and manage the Multimedia session that comprises voip call.

Carry out therein in the concrete example of VoIP communication, first distant station 101 is realized sip user agent client (UAC) 111, and this UAC 111 has initiated and set up the SIP session of supporting voip call.UAC 111 is responsible for initiating the SIP request, so that change the SIP session parameter.

Similarly, second distant station 103 is realized sip user agent servers (UAS) 113, and this UAS 113 can receive the SIP request and can enter negotiations process with UAC 111, changes the SIP session parameter with the request according to UAC 111.

Although should be appreciated that Fig. 1 only shows first distant station 101 that comprises UAC 111 for clarity and brevity and comprise that second distant station, 103, the first distant stations 101 of UAS 113 can comprise that also the UAS and second distant station 103 also can comprise UAC.In other words, the SIP session parameter also can change by second distant station 103.

In the example of Fig. 1, IMS 109 comprises the Session Border Controller (SBC) 115 at the point of interface place between a RAN 105 and the IMS 109.SBC is the equipment that uses in some voip networks, with to set up, carry out with end call in the signaling and the Media Stream that involve apply control.SBC is positioned in the signaling and/or media path between calling party and the callee.At last, SBC allow its owner control can by its KOC kind of call carried out of resident network, and overcome by for example some problems of the voip call that fire compartment wall causes.In this example, SBC 115 is in the path of signaling between first and second distant stations 101,103 and media communication.

In the example of Fig. 1, SBC 115 is coupled to sip server 117, and sip server 117 further is coupled to the 2nd RAN by IMS 109.Be to be understood that, although Fig. 1 illustrates in SBC 115 and sip server 117 and the direct connection between sip server 117 and the 2nd RAN 107, but this only for purposes of illustration, and actual the connection usually realizes via many middle IMS network elements.Particularly, the 2nd RAN 107 can be coupled to IMS 109 via the SBC similar to the SBC 115 of a RAN 105.

Usually, IMS will comprise more than physical embodiments of sip server, and sip server 117 can be regarded as the representative of all sip servers of being associated with first and second distant stations 101,103.Sip server has logic and physical function simultaneously.Each example of sip server in the IMS network can be played the part of role passive or active in the exchange of SIP signaling.The exemplary functions of sip server comprises (but being not limited to) user registration, authorizes, calls out routing and charging.

Therefore, in this system, carry out the signaling of supporting from the VoIP communication of first distant station, 101 to second distant stations 103 by SBC 115.

In this example, SBC 115 comprises back-to-back user agent (B2BUA), and this B2BUA is as the SIP Xin Lingdaili of UAC 111.Act on behalf of on the node (being SBC 115 in this example) in the IMS network in the sip message message flow that directly resides between two sides.It represents the calling party (UAC) of a side and the callee (UAS) of opposite side.For the calling party, B2BUA is as the callee.For the callee, B2BUA is as the calling party.

B2BUA can be regarded as the cascade corresponding to UAC and UAS particularly.In fact, the function of B2BUA is signaling and decision and the modification SIP signaling flow that can observe between two sides.This function allows Virtual network operator to carry out many IMS inter-related tasks, comprises value-added service, call manager and safety.In this example, B2BUA resides on the SBC 115, but should be appreciated that B2BUA can reside on other nodes in other embodiments.

In most of situation, sip agent equipment has to transmit its signaling message, so that keep the integrality in the signaling paths.This comprises that SIP/SDP consults.As described previously, in the IMS network of supporting mobile distant station, the radio condition of the variation of distant station may influence the quality of air interface communication significantly.In order to address this problem, SIP allows the dynamic multiple aspect of negotiation communication again.Particularly, SIP allows to carry out between UAC 111 and UAS 117 and consults again to change the source code scheme.

For VoIP communication, can use many voice codec schemes, comprise different audio coder ﹠ decoder (codec)s and different coding parameters.These schemes are vicissitudinous to the sensitiveness of disadvantageous propagation conditions, and some encoding schemes are to restore for the radio condition of difference, and other encoding scheme needs good wireless electricity condition, but better speech quality can be provided.SIP allows the negotiation of dynamic initiation of UAC and UAS, so that change the codec of current use.

Therefore, in the mobile SIP system, the change of propagation conditions may cause the UAC request to use new codec.Particularly, if propagation conditions improves, then UAC can ask codec is become the lower codec (normally having higher data speed) that still has better quality of nerve, if and the propagation conditions deterioration, but then UAC can ask codec become that nerve is higher to have a low-qualityer codec (normally having lower data rate).

Yet as shown in Figure 2, each request changes codec and all initiates negotiations process, wherein the many sip messages of exchange between institute's involved parties and intermediate network element.This has increased signaling consumption and has therefore increased the IMS offered load.And for the mobile remote unit of for example fast moving, radio propagation changes rapidly and therefore a large amount of codecs changes and may take place, thereby has caused a large amount of SIP signalings.This is illustrated in Fig. 2, and how the radio environment that Fig. 2 shows quick change causes a large amount of media codec negotiations that spreads all over network.In concrete example, No. eight codecs took place in the illustrated time interval changed.In addition, in order to use high network bandwidth resources, this has also increased the computation burden on the element that is involved, and has increased the computation burden on the UAS especially.

In the system of Fig. 1, B2BUA comprises filtering function, and this filtering function is carried out the filtration of SIP/SDP signaling.Particularly, B2BUA has been realized filtration or throttling algorithm, and this algorithm has reduced the number that is forwarded to the codec change scheme request of UAS 113 from UAC 111.Therefore, in this system, the subclass that only will come from the sip message of UAC 111 and request change codec is forwarded to UAS 113.Therefore, the filtering function of B2BUA can suppress to change request from some codecs of UAC 111.This can cause (downstream) signaling among the IMS 109 to reduce and can reduce computation burden on the UAS 113, because only need codec to change to consult and the subclass of codec change.

The filter operation of SIP/SDP message is preferably such that terminal use's experience keeps the influence that not changed by radio condition, makes the influence to the downstream signaling consumption minimize simultaneously.

Fig. 3 illustrates the example of some functional blocks of B2BUA.B2BUA comprises B2BUA UAS 301, and this UAS 301 is as the UAS operation that is used for UAC 111.Therefore, the SIP session negotiation request is transferred to B2BUA UAS 301 from UAC 111, and from UAC 111, UAS 301 is as the UAS of second distant station 113.

B2BUA further comprises B2BUA UAC 303, and this UAC 303 is as the UAC operation of the UAS 113 that is used for second distant station (UAS in the middle of perhaps any).Therefore, in order to change the parameter of SIP session, such as changing codec, B2BUA UAC 303 initiates negotiation procedure thus to UAS 113 transmitting SIP session negotiation request.

B2BUA also comprises filtering treater function 305, and this filtering treater function 305 is docked between B2BUA UAS 301 and the B2BUA UAC 303.The SIP session negotiation request that filtering treater 305 filters from UAC 111 is so that only be forwarded to UAS 113 with its subclass.

Particularly, the negotiation frequency criterion of filtering treater 305 assessment SIP session negotiation request, and only transmit the SIP session negotiation request that satisfies this criterion.Therefore, for each SIP session negotiation request assessment level all, and if satisfy this criterion, then this request is forwarded to USA113.If do not satisfy this criterion, then B2BUA is not forwarded to request UAS 113.

Should be appreciated that any suitable criterion that is used to assess the request of whether transmitting can be realized by filtering treater 305.

Fig. 4 illustrates the concrete example of the operation of B2BUA.This example is corresponding to the illustrative case of Fig. 2 and illustrate the restriction effect of being carried out by B2BUA.This example is corresponding to the example that wherein dynamically changes the VoIP audio coder ﹠ decoder (codec) according to radio condition between the lower codec of the higher codec of nerve and nerve.Particularly, when measured reception level increase was higher than given threshold value, the low still higher codec of quality of nerve was changed in UAC 111 requests.When being reduced to given threshold value under the reception level, but the lower codec of the higher quality of nerve is changed in UAC 111 requests.The request that changes codec asks the UAC 111 of SIP INVITE (invitation) message of codec change to excite (instigate) by transmission.

The SIP INVITE is received by B2BUA UAS 301.It is forwarded to filtering treater 305 then, filtering treater 305 assessment negotiation frequency criterion.If satisfy this criterion, then the SIP INVITE is forwarded to UAS 113 via sip server 117.

In this example, a SIP INVITE satisfies criterion, therefore this SIPINVITE forwards is arrived UAS 113, thereby has caused codec to change the carrying out of negotiations process.Particularly, UAS 113 echo reply codecs change the SIP 200 OK message of request.

Therefore, satisfy in the example of criterion in the SIP session negotiation request, B2BUA continues to transmit all message between UAC 111 and UAS 113 of the negotiations process that is excited.In other words, if initial request message satisfies this criterion, then this excites complete negotiations process.

If do not satisfy this criterion, then the SIP session negotiation request by throttling and not with transmission of messages to UAS 113.In the example of Fig. 4, the second and the 3rd message does not satisfy this criterion, and therefore not to UAS 113 transmitting SIP session negotiation request, has reduced the signaling consumption among the IMS109 thus in fact.

Should be appreciated that in different embodiment the operation of not satisfying the B2BUA in the situation of criterion can be different.

For example, in certain embodiments, B2BUA can transmit back UAC111 with consulting refuse information, changes thereby cause abandoning the SIP session.

In the example of Fig. 4, B2BUA continues to carry out to be consulted and the change codec.Particularly, B2BUA returns the 200OK transmission of messages UAC 111 and continues to change codec.Therefore, B2BUA changes VoIP communication between UAC 111 and B2BUA using new codec, and the communication of the VoIP between B2BUA and UAS 111 continues to use old codec.Therefore, in this case, B2BUA has also realized being used for speech data is converted to from a codec scheme code converter of another codec scheme.

Therefore, in this embodiment, B2BUA carry out transfer process in addition and be supported in UAC 111 simultaneously and B2BUA UAS 301 between a SIP session setting, be supported in the different SIP session setting between B2BUA UAC 303 and the UAS 113 simultaneously.The one SIP session is provided with the setting that changes request corresponding to the up-to-date SIP session that receives from UAC 111, and the 2nd SIP session setting changes the setting of request corresponding to a last SIP session that sends to UAS 113.

This method can allow dynamically to change codec to adapt to air interface radio conditions under the situation that does not cause a large amount of signaling consumptions.In concrete example, for the given time interval, eight end-to-end negotiations are reduced to three negotiations.Especially, take place therein in the environment that quick change that frequent codec changes propagates, signaling can obviously reduce.

In described system, B2BUA is configured to utilize the specified default parameters set that meets predetermined quality of service requirement to make a call to UAS 113.Therefore, particularly, B2BUA is established, to use default codec and to utilize predetermined bandwidth parameter etc. to call out to UAS 113 and initiate.

Should be appreciated that concrete throttling algorithm and negotiation frequency criterion can be implemented, to adapt to concrete preference and the requirement of independent embodiment.

Particularly, B2BUA can stop that the SIP/SDP of two-forty consults again, and allows the negotiation request of low rate to pass through network.

As a specific example, negotiation frequency criterion can comprise that the average frequency of the SIP session negotiation request of being transmitted is lower than the requirement of threshold value.For example, B2BUA can be measured the frequency of SIP session negotiation request, and can use the reasonable time constant that determined frequency is carried out low-pass filter.If the frequency of institute's low-pass filter is lower than specified value, then can allow the SIP session negotiation request by UAS 113, and if the frequency of institute's low-pass filter be higher than threshold value, then stop the SIP session negotiation request.

As another example, B2BUA can be alternatively or duration of requiring in addition when last SIP session negotiation request is forwarded to UAS 113, to rise surpass given threshold value.Minimum time between this negotiation request that will allow just be sent out, therefore and guarantee the maximum rate consulting to ask, and therefore guarantee maximum signaling consumption.

In certain embodiments, negotiation frequency criterion is included in the requirement of the maximum number N of the SIP session negotiation request that allows forwarding among the given time interval T.Therefore, B2BUA adopts filter algorithm, consults again to pass through only to allow N in configurable time T.

For example, for given period of time T, distant station can move to poor radio propagation environment and return good environment from good radio propagation environment.In the change of attempting the reply radio propagation condition, UAC 111 carries out never recoverable codec to recoverable codec, and returns the SIP negotiation set of the codec that can not restore.In other words, twice independently negotiation arranged in time interval T.If identical situation takes place, then will always have four negotiations initiating by UAC 111 in following second interval T of first interval T closely.Yet, if the B2BUA filter is configured to only consult request, the decreased number twice of end-to-end negotiation by one in the period of time T of each disappearance.

In certain embodiments, negotiation frequency criterion has realized the different sub-criterion of different SIP session negotiation request.Particularly, than change, can use different criterions to the change of higher quality of service parameter from low QoS parameter from the higher quality of service parameter to low QoS parameter.This can the desired service quality of permission system deflection.

For example, codec that quality is higher is carried out the communication between the B2BUA and second distant station 103 if current use nerve is low, then can always allow to pass through from the SIP request of UAC 111, so that guarantee high-quality.Yet, rising when being forwarded through after the given time interval since last SIP request, can only allow to pass through from the SIP request of changing into low quality codec from quality codecs of UAC 111.This can make the communication deflection better quality between the B2BUA and second distant station 103, and especially, if use low-quality codec, can prevent that then the voice communication on this link from only using low-quality codec from the communication of first distant station 101.

The application of negotiation frequency criterion can cause some SIP requests to be blocked, so that it is identical with the last SIP request that is forwarded to UAS 113 to satisfy next SIP request of this negotiation frequency criterion.For example, after codec changes into the request of quality codecs, can stop the subsequent request of changing into low quality codec making of being transmitted.Next request of being initiated by UAC 111 will be the request of changing into quality codecs.Yet, although this request can not need to transmit this message than the late required duration of last request.Therefore, in certain embodiments, B2BUA can further stop and the identical SIP request of a last request that is forwarded.

In certain embodiments, negotiation frequency criterion can dynamically change.Therefore, B2BUA can the dynamic monitoring parameter and is correspondingly changed negotiation frequency criterion.

Particularly, can be in response to load or the congested modification negotiation frequency criterion of IMS.For example, if, then being useful on the ample resources and the B2BUA of complete signaling less than given threshold value, load can allow to transmit all requests.Yet, for ever-increasing load, can use strict further requirement, so that reduce signaling consumption and discharge more resources.For example, for ever-increasing load, can reduce the request number that in given interval, allows forwarding.

In certain embodiments, can revise negotiation frequency criterion in response to the quantity of the SIP session negotiation request that receives.For example, B2BUA can be realized the negotiated speed limit from main regulation.Therefore, the frequent negotiation request in time interval T can cause transmitting the reduction (for example, being reduced to configurable minimum value) of request N.On the contrary, the not frequent negotiation request in time interval T can cause the increase (being increased to configurable maximum) of N.

Should be appreciated that described method provides many advantages, comprise one or more in for example following:

● can realize the signaling consumption that reduces.

● can realize the minimizing of fixed network bandwidth requirement.

● can realize the minimizing of wireless network bandwidth requirement.

● the influence of the radio condition of the variation in the IMS core is minimized.

● can realize the minimizing of the computation burden of core IMS network element.

● can realize in the non-IMS core network element minimizing of the computation burden of (and end user device in) in particular.

● can realize the minimizing of the capital expenditure of Virtual network operator.

● can realize the minimizing of the operating cost of Virtual network operator.

Fig. 5 illustrates the method for operation according to the B2BUA of some embodiments of the present invention.

This method begins in step 501, and wherein B2BUA UAS 301 receives air interface SIP session negotiation request from UAC 111.

After the step 501 is step 503, the negotiation frequency criterion of filtering treater 305 assessment SIP session negotiation request in step 503.

After the step 503 is step 505, and B2BUA UAC 303 only transmits the SIP session negotiation request that satisfies this negotiation frequency criterion to UAS 113 in step 505.

Should be appreciated that for the description above for the purpose of clear and described embodiments of the invention with reference to different functional unit and processors.Yet, it is evident that, do not impairing under the situation of the present invention, can use any appropriate functional between different function units or processor to distribute.For example, can carry out the illustrated function of carrying out by independent processor or controller by identical processor or controller.Therefore, should only be regarded as reference with reference to concrete functional unit and be used to provide the appropriate device of described function, and not represent strict logic OR physical structure or tissue.

The present invention can realize with any suitable form that comprises hardware, software, firmware or its any combination.The present invention can be implemented at least partly as the computer software that moves on one or more data processors and/or the digital signal processor alternatively.The element of embodiments of the invention and parts can physically, functionally and logically be realized in any suitable manner.In fact, function can realize in individual unit, a plurality of unit that perhaps the part as other functional units realizes.Similarly, the present invention can realize in individual unit or can physically and functionally be distributed between the different unit and processor.

Although described the present invention, be not intended to the concrete form that limit the invention to set forth herein in conjunction with some embodiment.Or rather, scope of the present invention is only defined by the appended claims.In addition, although as if can describe feature in conjunction with specific embodiment, one of ordinary skill in the art appreciates that can described embodiment combined according to the invention various features.In the claims, term " comprises " existence of not getting rid of other elements or step.

And although list separately, a plurality of means, element or method step can be by for example, and individual unit or processor are realized.In addition, although separately feature can be included in the different claims, these features can advantageously make up, and be included in the different claims be not the hint combination of features be infeasible and/or disadvantageous.And the feature that comprises in a class claim is not that hint is limited to such, but represents that this feature according to circumstances can be applied to other claim classes equally.And the order of the feature in the claim is not any concrete order that hint these feature works institute must adopt, and especially, and the order of the independent step in the claim to a method is not to hint that these steps must carry out in proper order with this.Or rather, this step can be carried out with any suitable order.

Claims (10)

1. network element that is used for internet protocol multimedia subsystem IMS, described network element comprises the back-to-back user agent B2BUA, described B2BUA is configured to:

The User Agent Client UAC of the distant station of supporting from radio air interfaces receives session interface protocol SIP session negotiation request;

Assess the negotiation frequency criterion of described SIP session negotiation request; And

Only transmit the described SIP session negotiation request that satisfies described negotiation frequency criterion to remote user agent server UAS.

2. network element as claimed in claim 1, wherein said B2BUA is further configured to supporting a SIP session that is used for described UAC that the different SIP session setting of supporting to be used for described UAS simultaneously is set, a described SIP session setting is provided with corresponding to the SIP of the SIP session negotiation request that is blocked, and described different SIP session setting is provided with corresponding to the SIP of the SIP session negotiation request that is forwarded.

3. network element as claimed in claim 1, wherein said negotiation frequency criterion comprises following requirement: the average frequency of the SIP session negotiation request that is forwarded is lower than threshold value.

4. network element as claimed in claim 1, wherein said negotiation frequency criterion comprises following requirement: the duration of rising when the SIP session negotiation request is forwarded to described UAS surpasses threshold value.

5. network element as claimed in claim 1, wherein said negotiation frequency criterion comprises following requirement: transmit N SIP session negotiation request of maximum number in time interval T.

6. network element as claimed in claim 1, wherein said negotiation frequency criterion comprise the first sub-criterion and the different sub-criterion that is used to consult to change into from low service quality setting the higher quality of service setting that is used to consult to change into from the higher quality of service setting low service quality setting.

7. network element as claimed in claim 1, wherein said negotiation frequency criterion comprises following requirement: if the SIP session negotiation request is different from the SIP session negotiation request of up-to-date forwarding, then only transmit described SIP session negotiation request to described UAC.

8. network element as claimed in claim 1 further comprises the device that is used for rewriting in response to the load of described IMS described negotiation frequency criterion.

9. network element as claimed in claim 1 further comprises being used for rewriting the device of described negotiation frequency criterion in response to the quantity of the SIP session negotiation request that is received.

10. method of operation that is used for the network element of internet protocol multimedia subsystem IMS, described network element comprises the back-to-back user agent B2BUA, described method comprises by described B2BUA carries out the following step:

The User Agent Client UAC of the distant station of supporting from radio air interfaces receives session interface protocol SIP session negotiation request;

Assess the negotiation frequency criterion of described SIP session negotiation request; And

Only transmit the described SIP session negotiation request that satisfies described negotiation frequency criterion to remote user agent server UAS.

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