CN101743769B - Method and apparatus for inter-technology handoff of a user equipment - Google Patents

Abstract

In order to facilitate a handoff between a legacy circuit switched network (110) and a packet data network (120), such as a 3GPP LTE, 3GPP2 UMB, or WiMAX network, of a communication session anchored in an IMS Voice Call Continuity Application Server (VCC AS) (158), a Circuit Switched Proxy (CS Proxy) (132) is provided in the packet data network that communicates with a Mobile Switching Center (MSC) (118) of the circuit switched network. The CS Proxy allows the packet data network to communicate with the VCC AS, the MSC to communicate with the packet data network, and the MSC to communicate with the VCC AS via the packet data network, thereby allowing an exchange of handoff-related information between the packet data network and the VCC AS, the packet data network and the circuit switched network, and the circuit switched network and the VCC AS via the packet data network.

Description

For the method and the equipment that switch between the technology of subscriber equipment

The cross reference of related application

The application requires the provisional application sequence number 60/944 that is entitled as " METHOD ANDAPPARATUS FOR INTER-TECHNOLOGY HANDOFF OF A USEREQUIPMENT " of submitting on June 18th, 2007,674 priority, it is for the applicant is common and its overall content is merged in herein by reference.

Technical field

The present invention relates generally to wireless communication system, and more specifically, relate to the transfer of the subscriber equipment between the cordless communication network of realizing different air interface technologies.

Background technology

The evolution of radio communication has caused the procreation of the network of the different air interface with different technologies and correspondence.Result, in the process of individual call, wireless user equipment (UE) may be roamed between multiple radio access networks (RAN), wherein each such RAN realizes the technology that is different from other RAN in the plurality of RAN, for example, the second generation (2G) circuit switching RAN, such as GSM (global system for mobile communications) network, it mainly provides circuit voice service, and grouped data RAN, such as 3GPP LTE of future generation (third generation partnership projects Long Term Evolution scheme) network, 3GPP2 UMB (third generation partnership projects 2 Ultra-Mobile Broadbands) network, WiMAX network, or based on the wireless fidelity network of IEEE 802 standards, it provides packet-switched the Internet protocol voice (VoIP) and other data related services.

When UE is at circuit switching RAN with provide while roaming between the grouped data RAN of packet data service, for systematic function advantageously, UE switches between circuit switching RAN and grouped data RAN.For example, because of the factor of the available horsepower located such as decline, adjacent channel and common-channel interference and serving BS (BS) or radio access network (RAN), the channel condition associated with the latter RAN may be than more favourable with the associated channel condition of the former RAN.As another example, the operator of legacy circuit network and packet data network may be for the object of system load balance by UE from such Network Mobility to another network.In internet protocol multi-media sub-system (IMS), involve the calling of UE in current grappling, and need to keep grappling this while involving the calling of UE, additionally make UE from 2G network to 3GPP LTE, the switching of 3GPP2 UMB or WiMAX network is complicated.As known in the art, IMS should not understand the transport layer transmitting below IMS data.

Between the RAN technology of 3GPP LTE, 3GPP2 UMB and WiMAX, transfer standard is in its initial stage.As a result, still there is not the method being defined for switching the voice conversation of UE between the legacy circuit-switched networks network such as GSM network and 3GPP LTE, 3GPP2 UMB or WiMAX network.Therefore, need to be a kind of for realizing method and the equipment of such switching.

Brief description of the drawings

Fig. 1 is the block diagram of wireless communication system according to various embodiments of the present invention.

Fig. 2 is the block diagram of the subscriber equipment of Fig. 1 according to an embodiment of the invention.

Fig. 3 is Mobility Management Entity/circuit switching agency's of Fig. 1 according to an embodiment of the invention block diagram.

Fig. 4 is the block diagram of the mobile switching centre of Fig. 1 according to an embodiment of the invention.

Fig. 5 A is according to various embodiments of the present invention, in the time that audio call is switched to the circuit-switched network of Fig. 1 from the packet data network of Fig. 1, and the signal flow graph of the method that the communication system of Fig. 1 is carried out.

Fig. 5 B is the continuous figure of the signal flow graph of Fig. 5 A, and it shows according to various embodiments of the present invention, in the time that audio call is switched to the circuit-switched network of Fig. 1 from the packet data network of Fig. 1, and the method that the communication system of Fig. 1 is carried out.

Fig. 6 A is according to various embodiments of the present invention, in the time that audio call is switched to the packet data network of Fig. 1 from the circuit-switched network of Fig. 1, and the signal flow graph of the method that the communication system of Fig. 1 is carried out.

Fig. 6 B is the continuous figure of the signal flow graph of Fig. 6 A, and it shows according to various embodiments of the present invention, in the time that audio call is switched to the packet data network of Fig. 1 from the circuit-switched network of Fig. 1, and the method that the communication system of Fig. 1 is carried out.

Fig. 6 C is the continuous figure of the signal flow graph of Fig. 6 A and 6B, and it shows according to various embodiments of the present invention, in the time that audio call is switched to the packet data network of Fig. 1 from the circuit-switched network of Fig. 1, and the method that the communication system of Fig. 1 is carried out.

Fig. 7 is the block diagram of the application server for continuity of voice call of Fig. 1 according to an embodiment of the invention.

Embodiment

Need now a kind of legacy circuit-switched networks network and method and equipment such as the switching of the voice conversation between the packet data network of 3GPP LTE, 3GPP2UMB or WiMAX network realized, wherein voice conversation is anchored in IMS application server for continuity of voice call (VCC AS), in order to solve this needs, in the packet data network of communicating by letter with the mobile switching centre (MSC) of circuit-switched network, provide circuit switching agency (CS agency).This CS agency allows this packet data network to communicate by letter with this VCC AS, allow this MSC and this packet data network communication, and allow this MSC to communicate by letter with this VCC AS via this packet data network, allow thus the exchange of the handover relevant information between this packet data network and this VCC AS, the exchange of the handover relevant information via this packet data network between the exchange of the handover relevant information between this packet data network and this circuit-switched network and this circuit-switched network and this VCC AS.

Conventionally, embodiments of the invention comprise a kind of method of switching between technology for the communication session from packet data network to circuit-switched network.The method comprises: via this packet data network to subscriber equipment (UE) transmit forward link session service and certainly this UE receive reverse link session service, determine and switch communication session, and in response to determining, this communication session is called out and is switched to this circuit-switched network, transmit the information about the target mobile switching centre (MSC) of this circuit-switched network by the circuit switching agency (CS agency) of this packet data network to this UE.The method further comprises: transmit Target Cell Identifier, MSC mark and other information by this UE and via this packet data network to application server for continuity of voice call (VCC AS), prepared to transfer via this target MSC of CS agency instruction of this packet data network by this VCC AS, and continue this Session Anchor in this VCC AS.The method further comprises: obtain this UE by the subsystem of objective base station associated with this target MSC (BSS), and provide communication session service by this target BS S to this UE.

Another embodiment of the present invention comprises a kind of method of switching between technology for the service from circuit-switched network to packet data network.The method comprises: via this circuit-switched network to UE transmit forward link service business and certainly this UE receive reverse link service business, determine and switch communication session, switch this communication session in response to determining, BSS by this circuit-switched network transmits this communication session is called out to the request that is switched to this packet data network to the n MSC of this circuit-switched network, and, in response to receiving this handover request, act on behalf of to the CS of this packet data network the request that transmission preparations are switched by this MSC.The method further comprises: the VCC AS exchanging handover information by this CS agency with internet protocol multi-media sub-system (IMS), provide by this CS agency the handover information receiving from this VCC AS to this MSC, continuation by this Session Anchor in this VCC AS, indicate this UE to access this packet data network by this circuit-switched network, obtain this UE by the radio access network of this packet data network, and, provide service by this packet data network to this subscriber equipment.

The equipment that between a kind of technology providing between circuit-switched network and packet data network, service is switched is provided another embodiment of the present invention.This equipment comprises CS agency, and it can operate in this packet data network and comprise processor, this processor be suitable for and the MSC exchange mobile switching centre of this circuit-switched network between signaling and with IMS VCC AS exchanging handover related signaling.

Another embodiment of the present invention comprises a kind of MSC, its support circuit-switched audio call and comprise for and the CS agency exchange mobile switching centre of packet data network between the device of signaling.

An embodiment more of the present invention comprises a kind of application server for continuity of voice call, and it is suitable for the circuit switching agency exchange MAP information receiving and transmitting with packet data network.

Forward now accompanying drawing to, can describe more all sidedly the present invention by reference to Fig. 1～7.Fig. 1 is the block diagram of wireless communication system 100 according to various embodiments of the present invention.Communication system 100 comprises wireless user equipment (UE) 102, such as but not limited to, cell phone, radio telephone or personal digital assistant (PDA), personal computer (PC) or outfit are for the laptop computer of wireless voice communication.UE 102 can participate in calling out with the packetized voice data of packet data network 120 and further can participate in and the circuit voice call of circuit-switched network 110, and more specifically, can preferably communicate by letter with the radio access network (RAN) 122 of this packet data network via 3GPP LTE (third generation partnership projects Long Term Evolution scheme) agreement, and preferably communicate by letter with the BSS 112 of circuit-switched network via the legacy protocol such as GSM (global system for mobile communications) agreement.

Circuit-switched network 110 comprises base station sub-system (BSS) 112, and this BSS is coupled to mobile switching centre (MSC) 118.BSS 112 comprises transceiver 114, for example, base station transceiver (BTS), its can operational coupled to controller 116, for example, base station controller (BSC).MSC 118 comprises calling control and mobile management function (not shown) and function of exchange (not shown).

Packet data network 120 comprises the radio access network (RAN) 122 such as E-UTRAN (evolved universal terrestrial radio access network), radio access network (RAN) 122 comprises the transceiver 124 such as enode b, and this transceiver 124 is coupled to the controller 126 such as radio network controller (RNC).But, in other embodiments of the invention, can be carried out by single entity the function of transceiver and controller execution.RAN 122 is coupled to gateway 138 and Mobility Management Entity (MME) 134.Preferably, gateway 138 comprises one or more gateways (service GWG) (not shown) and public data network (PDN) gateway (not shown).Circuit switching agency (CS agency) 132 functions can be included in MME 134, or comprise in other embodiments of the invention, and CS agency 132 can separate with this MME.CS agency 132 further via " E " interface coupling to MSC 118, via " S6x " interface coupling to home subscriber servers (HSS) 152, for retrieving application server for continuity of voice call information from this HSS in other information, and via " SGx " interface coupling to application server for continuity of voice call (VCC AS) 158.CS agency 132 imitates MSC, that is, for MSC 118 be rendered as another MSC and circuit-switched network 110 is provided and packet data network 120 between circuit switching transfer function.For another angle, CS agency 132 provides circuit-switched network function in packet data network 120, allows circuit-switched network 110 to intercom mutually such as agreement between the system of MAP (MAP) via " E " interface and by using with packet data network 120.CS agency 132 further promotes the communication between MSC 118 and VCC AS 158 via packet data network 120.MME 134 further via " S11 " interface coupling to gateway 138 and via " S3 " interface coupling to Serving GPRS Support Node (SGSN) 136.Gateway 138 further via " S4 " interface coupling to SGSN136 and via " S7 " interface coupling to policy control and charging rule functions (PCRF) 140.CS agency 132, MME 134, SGSN 136 and gateway 138 are called the evolution block core (EPC) 130 of packet data network 120 jointly.

Circuit-switched network 110 and packet data network 120 are all coupled to IP Multimedia System (IMS) 150.The MSC 118 of circuit-switched network 110 is coupled to IMS 150, more specifically, via bearing interface, for example, time division multiplexing pulse code modulation (PCM on TDM) interface, and signaling interface, for example, ISDN User Part (ISUP) interface, is coupled to MGCF (MGCF)/media gateway (MGW) 154 of IMS150.In various embodiment of the present invention, MGCF/MGW 154 can realize in consolidated network entity or in the network entity separating.MME 134 is coupled to IMS 150, and the HSS 152 to IMS 150 via " S6a " interface coupling preferably.Gateway 138 has via " SGi " interface and signaling and bearer connection IMS 150, and PCRF 140 via " Rx+ " interface coupling to IMS 150.

IMS 150 comprises: IMS core network 156, and it comprises HSS 152, MGCF/MGW154 and other network entities, such as CSCF (CSCF) (not shown); With multiple application servers, comprising can be via VCC AS 158 and the telco application server (TAS) 160 of this IMS core network access.Except being coupled to MSC 118, MGCF/MGW 154 is further coupled to EPC 130, and is coupled to particularly gateway 138, and is each gateway providing for IMS 150 of circuit-switched network 110 and packet data network 120.Gateway 138 can further be coupled to HSS 152 via CSCF (CSCF) (not shown) of this IMS core network.When UE 102 participates in being anchored in IMS 150 during with audio call circuit-switched network 110, MGCF/MGW 154 can be for example, based on real-time protocol (RTP)/User Datagram Protoco (UDP)/Internet protocol (RTP/UDP/IP) protocol suite, the pulse code modulation receiving from MSC 118 (PCM) signal is converted to packet, be used in this IMS network route, and the speech data receiving from this IMS network can be converted to the PCM form on TDM (time division multiplexing), for routing to MSC 118.

Except " E ", " SGx " and " S6x " interface, interface listed above is known in the art, and will not be described in greater detail herein.And, although described the individual interface between many network elements of communication system 100 herein, but the each interconnection between element can comprise multiple interconnection and/or interface, such as one or more signaling interfaces, for example, for exchanging the interface of SIP, ISUP, MAP or Megaco message, and bearing interface or path, this path is for switched voice information.

The each of BSS 112 and RAN 122 provides radio communication service via corresponding air interface 104,106 to the subscriber equipment (UE) of the overlay area that is arranged in BSS or RAN.Each air interface 104,106 comprises forward link, and this forward link comprises pilot channel, at least one forward and forward link is public and Dedicated Signaling Channel.Each air interface 104,106 further comprises reverse link, and this reverse link comprises at least one reverse link traffic channel, reverse link public and Dedicated Signaling Channel and access channel.

With reference now to Fig. 2,, provide the architecture of UE 102 according to embodiments of the invention.UE 102 comprises processor 202, such as known these other equipment of one or more microprocessors, microcontroller, digital signal processor (DSP), its combination or those of ordinary skill in the art, this processor is configured to carry out the function described herein that UE 102 carries out.UE 102 further comprises at least one memory devices 204, such as random access memory (RAM), dynamic random access memory (DRAM) and/or read-only memory (ROM) or its equivalent, this at least one memory devices 204 is coupled to processor and save data and program, and this program can be carried out and be allowed UE to carry out for operating necessary all functions in communication system 100 by associated processor.UE 102 can preserve the information of programming in advance at least one memory devices 204, and this information promotes the switching between network 110 and 120.

With reference now to Fig. 3,, provide MME 134/CS agency 132 architecture according to embodiments of the invention.This MME/CS agency comprises processor 302, such as known other the such equipment of one or more microprocessors, microcontroller, digital signal processor (DSP), its combination or those of ordinary skill in the art, this processor is configured to carry out the function described herein of carrying out as this MME/CS agency.This MME/CS agency further comprises at least one memory devices 304, it can comprise random access memory (RAM), dynamic random access memory (DRAM) and/or read-only memory (ROM) or its equivalent, this at least one memory devices 304 save datas and program, this program can be carried out and be allowed MME/CS agency to carry out for operating needed all functions in communication system 100 by associated processor.At least one memory devices 304 is further preserved the configuration information such as the neighbours MSC of MSC 118, for promote for or from the switching of such MSC.For example, such configuration information can comprise the agreement for information router is supported to the routing iinformation of such MSC, by such MSC and identifier, the transceiver comprising such as BSS and/or the identifier of controller of the BSS that supported by such MSC.The program of preferably, being preserved based at least one memory devices 304 by processor 302 and data realize CS agency 132.But in another embodiment of the present invention, CS agency 132 can be included in the network entity separating with MME 134.In the latter's example, CS agency 132 comprises the processor of himself and at least one associated memory devices of save data and program, this program can be carried out and be allowed this CS agency to carry out for operating needed all functions in communication system 100 by this processor, and at least one memory devices that the configuration information mentioned above of alternatively, preserving as MME 132 can be acted on behalf of by this CS is preserved or can between this MME and this CS agency, be distributed.

With reference now to Fig. 4 and 7,, provide the architecture of MSC 118 and VCCAS 158 according to embodiments of the invention.Each processor 402,702 comprising separately of MSC 118 and VCC AS 158, such as known other the such equipment of one or more microprocessors, microcontroller, digital signal processor (DSP), its combination or those of ordinary skill in the art, this processor is configured to carry out the function described herein of being carried out by MSC 118 and VCC AS 158.MSC 118 and VCC AS 158 all further comprise at least one memory devices 404,704 separately, such as random access memory (RAM), dynamic random access memory (DRAM) and/or read-only memory (ROM) or its equivalent, this at least one memory devices 404,704 is coupled to processor and save data and program, and this program can carry out and allow MSC and VCC AS to carry out for operating needed all functions in communication system 100 by associated processor.

The function described herein of being carried out by UE 102, MME 134, CS agency 132, MSC 118 and VCC AS 158 is realized or is realized in this software program and instruction by software program and instruction, and this software program and instruction are stored in corresponding at least one memory devices 204,304,404,704 associated with this UE, MME, CS agency, MSC and VCC AS and by carrying out with the associated processor 202,302,402,702 of this UE, MME, CS agency, MSC and VCC AS.But, those of ordinary skill in the art will be appreciated that, embodiments of the invention can be realized alternatively in hardware, for example, integrated circuit (IC), application-specific integrated circuit (ASIC) (ASIC) etc., such as the ASIC realizing in one or more of this UE, MME, CS agency, MSC and VCC AS.Based on the disclosure, those skilled in the art will easily can produce and realize such software and/or hardware the undo experimentation not in the situation that.

In order to make UE 102 participate in circuit service audio call or packetized voice data calling via circuit-switched network 110 or packet data network 120 respectively, UE 102, circuit-switched network 110 and packet data network 120 are all according to known wireless telecommunications protocols operation.Preferably legacy communications system of circuit-switched network 110, this legacy communications system provides circuit-switched communications service and operates according to GSM standard or GSM standard of future generation to the subscriber of this network (it can also provide packet data service) service.As illustrated herein, packet data network 120 is 3GPP LTE communication systems that packet data communication service is provided to the subscriber of this network service; But other applicable packet data network comprise 3GPP2 UMB and WiMAX packet data network.In order to ensure compatibility, radio system parameters and call processing program are indicated by standard, comprise by UE and serve the base station sub-system of this UE or call treatment step that other access networks are carried out and base station sub-system or other access networks and associated infrastructure between call treatment step.But, those of ordinary skill in the art will be appreciated that, packet data network 120 can be according to any one operation of supporting in the various wireless packet data communication systems of communication session based on multi-media packet data, such as IEEE (institute of electrical and electronic engineers) 802.xx standard, for example, 802.11,802.15,802.16 or 802.20 standards, and circuit-switched network 110 can be according to any one operation in the various known conventional wireless telecommunication system that provides circuit-switched communications to serve.

In communication system 100, in the time that UE 102 participates in audio call by one of circuit-switched network 110 and packet data network 120, UE may roam in system.As the result of roaming, may there is following situation, wherein need UE 102 to be switched to another network from one of circuit-switched network 110 and packet data network 120.For example, as known in the art, in the time that UE 102 roams and served by BSS 112 in communication system 100, UE 102 may receive the stronger signal from RAN 122.And similarly,, in the time that UE 102 roams and served by RAN 122 in communication system 100, UE 102 may receive the stronger signal from BSS 112.Typically, measure the pilot channel associated with this RAN or BSS by UE (such as UE 102), determine signal strength signal intensity.In the time that the pilot channel of serving RAN or BSS is weaker than the pilot channel of threshold value and another RAN or BSS, typically point out to need to switch.

As another example, and on circuit-switched network 110, operate the associated cost of UE 102 and may be different from and on packet data network 120, operate the associated cost of UE 102.And then the operator of network 110 and 120 can be to the different expense of using tricks that makes of each network.As a result, the user of UE 102 may be set as user preference, no matter when, in the time that UE can obtain the Traffic Channel in lower cost network, on this lower cost network, operates.In the time that UE 102 participates in the audio call in higher cost network and can obtain the Traffic Channel in lower cost network, if to the availability of the Traffic Channel in this lower cost network of user notification, UE, or the user of this UE can initiate the switching for this lower cost network.As another example, may preferably use video phone service but not audio call and packet data network 120 while supporting that but visual telephone circuit-switched network 110 is not supported the user of UE 102, the UE of the audio call in circuit-switched network 110 will be participated in actively, such as UE 102, move to packet data network 120.As another example, for the object of load balance, the object of considering for network cost, or owing to removing the Traffic Channel in overlay area so that promote the needs of urgency communication, operator such as the communication system of communication system 100 may find will to participate in actively the UE of an audio call in circuit-switched network 110, such as UE 102, move to packet data network 120, vice versa.

In order to promote the switching such as the UE of UE 102, communication system 100 provides a kind of method and equipment, in the time that UE participates in the communication session in arbitrary network actively, this communication session can comprise audio call and/or the non-voice calling such as video, and the method and equipment are for the active UE that switches between circuit-switched network 110 and packet data network 120.By the active switching of the communication session between circuit-switched network 110 and packet data network 120 is provided, communication system 100 guarantees that UE participated in and network 110 and 120 communication session one of at least actively in nearly all time, made to lose in handoff procedure the possibility minimum of voice or data service thus.

With reference now to Fig. 5 A and 5B,, signal flow graph 500 is provided, it illustrates the method that communication system 100 is carried out in the time that UE 102 is switched to circuit-switched network 110 from packet data network 120 according to various embodiments of the present invention.In the time that UE 102 participates in IMS telephone conversation (501～504) via packet data network 120, signal flow graph 500 starts, and this IMS telephone conversation is controlled by IMS 150, and particularly, is anchored in VCC AS 158.UE 102 communicates by letter with VCC AS 158 with MGCF/MGW 154 via RAN 122, EPC 130.

When UE 102 in via packet data network 120 and remote parties (not shown) such as audio call enliven communication session time, this UE monitors the quality of (506) and the each associated pilot tone of the RAN 122 of packet data network 120 and the BSS 112 of circuit-switched network 110, specifically signal strength signal intensity or alternatively, any quality in various other signal qualitys, such as signal to noise ratio (SNR), Carrier interference ratio (C/I), pilot power gross power (Ec/Io) ratio, bit error rate (BER) or frame error ratio (FER).UE 102 can monitor the pilot tone of each network 110,120 simultaneously or can in the time monitoring this pilot tone, between network, switch.UE102 can determine when or whether monitor the pilot tone associated with the BSS 112 of circuit-switched network 110 voluntarily, or can monitor this pilot tone in response to the instruction receiving from this pilot tone of supervision of packet network 120.

UE 102 reports according to known report code the pilot tone (multiple) that (506) monitor.For example, when in packet data network 120 operation UE 102 measuring circuit switching networks 110 (and more specifically, air interface 104) the quality of pilot tone and this quality while exceeding intersystem handover threshold value, or when the UE 102 of operation in packet data network 110 measures packet data network 120 (and more specifically, air interface 106) the quality of pilot tone of previous report and this quality during lower than intra-system handover threshold value, UE can return to RAN 122, and reports monitored pilot tone (multiple) to controller 126 particularly.Controller 126 is stored the pilot measurement of reporting subsequently.

Based on pilot measurement associated with RAN 122 and BSS 112 and that reported by UE 102, packet data network 120, and particularly, RAN 122, can determine that UE 102 is switched to circuit-switched network 110 and BSS 112 by (508).For example, when the pilot tone of RAN 122 is than (in the situation in signal strength threshold, lower than) pilot tone of the unfavorable and/or BSS 112 of intra-system handover threshold value is than (in the situation of signal strength threshold, exceeding) intersystem handover threshold value is when favourable, and this can point out to need to switch.As another example, and on network 110, operate the associated cost of UE102 and may be different from and on network 120, operate the associated cost of UE 102.And then the operator of network 110 and 120 can be to the different expense of using tricks that makes of each network.If circuit-switched network 110 is lower cost networks, no matter when in the time that the measurement of the pilot tone associated with this circuit-switched network is favourable than intersystem handover threshold value, the user of UE 102 can be programmed into the instruction of operation on circuit-switched network 110 in this UE.As another example, for the object of load balance, the object of considering for network cost, or owing to removing the Traffic Channel in overlay area so that promote the needs of urgency communication, no matter when in the time that the measurement of the pilot tone associated with circuit-switched network is favourable than intersystem handover threshold value, the operator of communication system 100 may find by participating in actively the UE of the communication session in grouped data 120, such as UE 102, to move to circuit-switched network 110.

In response to determining, UE 102 is switched to circuit-switched network 110 and BSS 112 from packet data network 120 and RAN 122, the request that communication session is switched in RAN 122 assemblings, this request comprises this measurement, mark target BS S, be BSS 112, and further identify to be switched UE, be i.e. UE 102.RAN 122 arrives EPC 130 by this request transmission (510) subsequently, and particularly, is sent to MME 134.Request based on this reception and the configuration information of preserving by reference to MME134, this MME determines (512) target MSC, be MSC 118, and the response of assembling to transfer request, and transmitted (514,516) via RAN 122 and return UE 102.This response comprises Target cell or sector, be BS 112 (and particularly, transceiver 114) identifier of target MSC 118 of the community of service or the identifier of sector, configuration information based in MME 134, such as MSC number or other routing iinformations and CS agency's 132 identifier, such as acting on behalf of associated Directory Number with this CS, for example number E.164, or other route related information.But, in another embodiment of the present invention, can in the time that UE 102 registers to packet data network 120, this CS agent identifier be offered to this UE 102.

In response to the transfer request response receiving from MME 134, UE 102 assembles SIP (Session initiation Protocol) REFER message and via packet data network 120, via RAN122 and EPC 130 (particularly, gateway 138), transmitted (518～520) to VCC AS158, this SIP REFER message comprises the identifier, VCC AS PSI (public service identity), CS agent identifier of Target cell or sector marker, target MSC 118 and for handing over to the required authentication in 2G CS territory, authorization and accounting (AAA) information.This CS agent identifier identifies this VCC AS by the CS agency of negotiation, i.e. CS agency 132, this be because, in the prior art, because agreement is incompatible, VCC AS can not be directly and MME negotiate.Preferably, UE 102 is sent to VCC AS 158 by sip message being encapsulated in IP packet by this SIP REFER message, transmits this IP packet on the user plane that this UE is connected to this VCC AS.In response to receiving this SIP FERER message, VCC AS 158 is preferably by assembling SIP 202 ACCEPT (SIP 202 accepts) message and via packet data network 120, via EPC 130, particularly, via gateway 138, with RAN 122, send it to UE 102, confirm the acceptance of the transfer that (522～524) propose to UE 102.

And in response to receiving this SIP FERER message, VCC AS 158 acts on behalf of 132 instruct MS C 118 via CS and prepares to transfer.,, in response to receiving this SIP FERER message, VCC AS 158 assembles and transmits (526) MAPPREPARE-HANDOVER (MAP prepares to switch) message to CS agency 132.MAP is the circuit-switched network agreement that can be used for communicating by letter between MSC.By comprising that at packet data network 120 CS agency 132, VCC AS 158 and MSC 118 all can negotiate with this packet data network, and can act on behalf of 132 negotiations with CS particularly, and further can mutually negotiate via this packet data network.

The MAP PREPARE-HANDOVER message that VCC AS 158 assembles comprises CS agent identifier, MSC identifier and AAA information.In response to receiving this MAPPREPARE-HANDOVER message, CS agency 132 transmits to target MSC 118 the MAP PREPARE-HANDOVER message that (528) comprise CS agent identifier and AAA information.In one embodiment of the invention, CS agency 132 can forward the MAP PREPARE-HANDOVER message receiving from VCC AS 158 or do not have with this CS agent identifier; But in another embodiment of the present invention, CS agency 132 can assemble and transmit and comprise some or another MAPPREPARE-HANDOVER message of all information of receiving from VCC AS 158.

In response to receiving this MAP PREPARE-HANDOVER message, MSC 118 assembles and transmits (530) to target BS S 112 and transfer request, preferably, HO-REQUEST (HO request) message, and as response, this BSS receives the confirmation of (532) this request certainly.MSC 118 further transmits (534) MAP PREPARE HANDOVERRESPONSE (MAP prepares handoff response) message to CS agency 132, it comprises the Handover Number (HO#) that the circuit for setting up between this MCS and MGCF/MGW 154 (and particularly, MGW) connects, the VCC AS identifier of transferring order (HO_CMD) and being identified at the application moving on the VCC AS of this communication session of grappling or calling.In response to receiving this MAPPREPARE-HANDOVER-RESPONSE message, CS agency 132 transmits (536) MAP PREPARE-HANDOVER-RESPONSE message to VCC AS 158, and it comprises VCC AS identifier, transfers number and transfers order.In one embodiment of the invention, CS agency 132 can forward the MAPPREPARE-HANDOVER-RESPONSE message receiving from target MSC 118; But in another embodiment of the present invention, CS agency 132 can assemble and transmit and comprise from some of MSC reception or another MAP PREPARE-HANDOVER-RESPONSE message of all information to VCC AS.

In response to this MAPPREPARE-HANDOVER-RESPONSE message receiving from CS agency 132, VCC AS 158 sets up (538～564) and is connected with the circuit of target MSC 118, and via this MSC, set up and being connected of UE 102 via circuit-switched network 110.More specifically, in response to this MAP PREPARE-HANDOVER-RESPONSE message receiving from CS agency 132, VCC AS 158 assembles and transmits (538) session invitation to MGCF/MGW 154, this session invitation is SIPINVITE message preferably, and it comprises transfers number and the Route Distinguisher associated with UE 102 and remote parties for communication session.In response to receiving this session invitation, MGCF/MGW 154 provides (540) to transfer number and for switching the reserved repeat circuit of communication session via the exchange of ISUP IAM (initial address message) and ISUP ACM (the complete message in address) message to target MSC 118.In response to receiving this transfer number, target MSC 118, preferably by transmit SIP PROGRESS (SIP process) message to VCCAS 158, is transferred and is carried out to this VCC AS notice (542).In response to receiving this SIP PROGRESS message, VCC AS 158 passes through via packet data network 120, via EPC 130 (particularly, gateway 138), with RAN 122, transmit SIP NOTIFY (SIP notice) message to UE 102, to this UE notice (544～546) in circuit-switched network 110 (and more specifically, at target MSC 118 places), resource is just being assigned to this UE, and wherein this SIP NOTIFY comprises transfer order.

And in response to receiving the request transferred (530), target BBS 112 obtains UE 102 and will distribute to UE 102 in the resource at BSS place.For example, target BS S 112 can this UE of paging or is indicated in addition this UE to access this BSS.In response to the access attempts receiving from this UE, target BS S 112 is to this UE Resources allocation, preferably by transmit HO-DETECTED (HO being detected) message to target MSC 118, detect that to this MSC notice (548) this BSS obtaining of UE 102 and this UE carry out.As response, target MSC 118 is notified the detection of (550,552) circuit-switched network 110 to UE 102 via packet data network 120 to VCC AS 158.; target MSC 118 is preferably by transmitting MAP PROGRESS-ACCESS-SIGNAL REQUEST (MAP process access request signal) message to CS agency 132; to this detection of CS agent advertisement (550) target BS S 112 to UE 102; the i.e. access attempts of this UE; and obtaining of this UE carried out.CS agency 132 is subsequently preferably by forwarding to VCC AS 158 the MAPPROGRESS-ACCESS-SIGNAL REQUEST message receiving, preferably, by this MAP message being encapsulated in sip message and transmitting this sip message to this VCC AS, notify the access attempts of (552) this UE and obtain to this VCC AS.

In the time that target BS S 112 has completed obtaining of UE 102, this BSS provides communication session related service and preferably by transmit HO-COMPLETE (HO completes) message to target MSC 118, obtains to the success of this MSC notice (554) this UE to this UE.In response to receiving this HO-COMPLETE message, target MSC 118 makes circuit be connected with UE 102 by this MSC.And in response to obtaining UE 102, target BS S 112 notifies (556,558) circuit-switched network 110 successfully to obtain UE 102 via packet data network 120 to VCC AS 158, and the resource triggering in packet data network 120 is removed.; target BS S 112 transmits MAPSEND-END-SIGNAL REQUEST (MAP sends end signal request) message by acting on behalf of 132 via MSC 118 to CS, successfully obtains UE 102 and triggers the resource removing in packet data network 120 to this MSC and this BSS of this CS agent advertisement (556).And then, CS agency 132, by this MAPSEND-END-SIGNAL REQUEST message is forwarded to VCC AS 158, successfully obtains UE 102 and triggers the resource removing in packet data network 120 to this VCC AS notice (558) circuit-switched network 110.In response to receiving this MAP SEND-END-SIGNALREQUEST message, VCC AS 158 preferably passes through via EPC 130 (particularly, gateway 138), transmit SIP BYE (SIP goodbye) message with RAN 122 to UE 102, indicate (560～562) this UE to stop the communication session of this UE in this packet data network via packet data network 120 and RAN 122.In response to receiving this SIP BYE message, UE 102 stops the bearer connection for this UE of packet data network 120.

In addition, successfully obtain UE 102 in response to notified target BS S 112, target MSC 118, preferably by transmit ISUP ANSWER (ISUP replys) message to MGCF/MGW 154, obtains to the success of this MGCF/MGW notice (564) this UE.MGCF/MGW 154 preferably responds the SIP 200OK message of the session invitation that this MGCF/MGW receives from VCC AS 158 subsequently by transmission, accept transfer to this VCC AS notice (566) circuit-switched network 110.

Now, UE 102 has been switched to circuit-switched network 110.As a result, need the resource that remains in advance UE 102 in removal packet data network 120.Therefore, accept transfer in response to notified circuit-switched network 110, VCC AS 158, via circuit switching agency, arranges the resource in packet data network 120 to discharge., VCC AS 158 consults the release of the resource of distributing to UE 102 in (568) packet data network 120 via CS agency 132.CS agency 132 consults the release of (570) packet data network resource via MME 134 and RAN 122 subsequently.Target MSC 118 is also by transmitting MAP-SEND-END-SIGNALRESPONSE (MAP sends end signal response) message to CS agency 132, notify (572) this UE to be switched to circuit-switched network 110 with BSS 112 and to have indicated this CS agency to discharge any MAP resource associated with UE 102 to VCC AS 158, this MAP-SEND-END-SIGNALRESPONSE message forwards (574) to VCC AS 158 by this CS agency.

In response to receiving this MAP-SEND-END-SIGNAL RESPONSE message, VCC AS 158 is by transmit SIP RE-INVITE (SIP re-invites) message to MGCF/MGW 154, and instruction (576) this MGCF/MGW makes the bearer path of communication session be connected with circuit-switched network 110 and is switched to circuit-switched communication session conversion plan.In response to receiving this SIP RE-INVITE message, MGCF/MGW 154 makes the bearer path of this communication session be connected with circuit-switched network 110, be switched to circuit-switched communication session conversion plan, and by transmitting SIP 200 OK message to VCC AS 158 to this VCC AS notice (578) this switching and conversion.Now, set up the circuit switched bearer path via target BS S 112, target MSC 118 and MGCF/MGW 154 between (580～583) UE 102 and VCC AS 158, and call flow diagram 500 finishes subsequently.

By the CS agency 132 in the packet data network 120 of the MSC 118 that is coupled to circuit-switched network 110 is provided, communication system 100 allows these MSC to communicate by letter with packet switching network and further communicate by letter with the VCC AS 158 of IMS 150 via packet data network.Therefore this MSC and VCC AS can be before the connections of setting up for the circuit-switched network of the UE that is switched, via this packet switching network, and switched circuit switching network message, and particularly, switched circuit switching network is transferred message, such as MAP message.By allowing MSC 118 and VCC AS 158 via the packet switching network transmitting-receiving that exchanges messages, communication system 100 has promoted the exchange of the handover relevant information between VCC AS and objective circuit switching network 110 that grappling calls out, allow thus this VCC AS to control the foundation of the communication session in objective circuit switching network, think to transfer and prepare.

CS agency 132 further promotes the transfer of communication session from circuit-switched network 110 to packet data network 120.With reference now to Fig. 6 A, 6B and 6C,, signal flow graph 600 is provided, it illustrates according to various embodiments of the present invention, in the time that UE 102 is switched to packet data network 120 from circuit-switched network 110, the method that communication system 100 is carried out.When UE 102 participates in the communication session of (602～613) and remote parties (not shown) via circuit-switched network 110, for example when audio call, signal flow graph 600 starts, and this communication session is controlled by IMS 150, and particularly, be anchored to VCC AS 158.Previously built vertical signaling paths (602～608) and bearer path (610～613).

In the time of the beared information of exchange such as voice messaging, UE 102 exchanges (613) beared information such as acoustic code speech via air interface 104 with BSS 112.In the event of acoustic code speech, BSS 112 receives this acoustic code speech via the reverse link traffic channel of air interface 104 from UE 102, be 64kbps pulse code modulation (PCM) (G.711) by this acoustic code speech transcoding, and this transcoding speech transmission (612) is arrived to MSC 118.Similarly, BSS 112 can be and the compatible vocoder format of UE 102 by the communication transcoding receiving from MSC 118, and launch (613) this transcoding information via the forward of air interface 104 to UE 102.MSC 118 forwards (611) to MGCG/MGW154 by the PCM signal receiving from BSS 112, and the PCM signal receiving certainly this MGCG/MGW is forwarded to (612) to this BSS.MGCG/MGW 154 is acoustic code speech by the PCM signal transcoding receiving from MSC 102, acoustic code speech is included in the packet that is preferably formatted as RTP/UDP/IP form, and by this packet route (610) to remote endpoint (not shown).The acoustic code voice conversion that MGCG/MGW 154 further comprises the packet receiving from remote parties be 64kbpsPCM (G.711) and by this PCM signal route (611) to MSC 120.In fact, can think that communication session has a side associated with UE 102 and communication system 100, be CALL1B (calling out 1B) (611～613), with a side associated with the external network of for example PSTN (PSTN) and remote parties, i.e. CALL 1A (calling out 1A) (610).

When UE 102 in circuit-switched network 110 (CALL 1B) enliven communication session time, this UE monitors the quality with the each associated pilot tone of the BSS 112 of circuit-switched network 110 and the RAN 122 of packet data network 120, specifically signal strength signal intensity or alternatively, any quality in various other signal qualitys, such as signal to noise ratio (SNR), Carrier interference ratio (C/I), pilot power gross power (Ec/Io) ratio, bit error rate (BER) or frame error ratio (FER).UE 102 can monitor the pilot tone of each network 110,120 simultaneously or can in the time monitoring this pilot tone, between network, switch.UE 102 can determine when or whether monitor the pilot tone associated with the RAN 122 of packet data network 120 voluntarily, or can monitor this pilot tone in response to the instruction receiving from this pilot tone of supervision of circuit-switched network 110 (and particularly, from one of BS 112 and MSC 118).

UE 102 reports according to known report code the pilot tone (multiple) that (616) monitor.For example, in the time that the pilot tone of circuit-switched network 110 monitoring exceedes intra-system handover threshold value, MS to BS 112, and particularly to controller 116, reports the strength of pilot channels of this pilot tone and measurement via the reverse link of air interface 104.Similarly, when the pilot tone monitoring is during lower than intra-system handover threshold value, this MS, being sent to via the reverse link of air interface 104 in the report of BSS, to BS 112, and particularly to controller 116, reports the pilot signal strength of this pilot tone and measurement.When the UE 102 operating in circuit-switched network 110 measures packet data network 120 (and more specifically, air interface 106) the quality of pilot tone and this quality while exceeding intersystem handover threshold value, or when operating in UE 102 measuring circuit switching networks 110 in this circuit-switched network (and more specifically, air interface 104) the quality of pilot tone of previous report and this quality during lower than intersystem handover threshold value, this UE returns to BS 112, and more specifically to controller 116, the pilot tone (multiple) that report (616) monitors.Controller 116 is stored the pilot measurement of reporting subsequently.

Based on pilot measurement associated with BS 112 and RAN 122 and that reported by UE 102, circuit-switched network 110, and particularly, source BSS 112 or source MSC 118, can determine subsequently UE 102 is switched to targeted packets data network 120 and target RAN 122.For example, when the pilot tone of BSS 112 is than (in the situation in signal strength threshold, lower than) pilot tone of the unfavorable and/or RAN 122 of intra-system handover threshold value is than (in the situation of signal strength threshold, exceeding) intersystem handover threshold value is when favourable, and this can point out to need to switch.As another example, and on network 110, operate the associated cost of UE 102 and may be different from and on network 120, operate the associated cost of UE 102.And then the operator of network 110 and 120 can be to the different expense of using tricks that makes of each network.If packet data network 120 is lower cost networks, no matter when in the time that the measurement of the pilot tone associated with this packet data network is favourable than intersystem handover threshold value, the user of UE 102 can be programmed into the instruction of operation on second network 120 in this MS.As another example, for the object of load balance, the object of considering for network cost, or owing to removing the Traffic Channel in overlay area so that promote the needs of urgency communication, no matter when in the time that the measurement of the pilot tone associated with packet data network is favourable than intersystem handover threshold value, the operator of communication system 100 may find by participating in actively the UE of the communication session in circuit network 110, such as UE 102, to move to packet data network 120.

In response to determining, UE 102 is switched to packet data network 120 and RAN 122 from circuit-switched network 110 and BSS 112, the request that communication session is switched in BSS 112 assemblings, this request comprises the identifier of this measurement, target RAN (being RAN 122) and the identifier of to be switched UE (being UE 102), moves and subscribes mark (IMSI) such as the world.BSS 112 arrives MSC 118 by this request transmission (618) subsequently.In response to receiving this handover request, MSC 118 assembles and to packet data network 120, and particularly, to CS agency 132, the message of transferring is prepared in (620) request that transmits, and this message is MAPPREPARE-HANDOVER-REQUEST message preferably, it comprises this CS agency's associated with this CS agency identifier, such as Directory Number, for example number E.164, or other route related information; The identifier of target MME (being MME 134); With UE identifier.

Prepare message in response to this transfer receiving from circuit-switched network 110 (from MSC 118), CS agency 132 determines the VCCAS application associated with UE 102 (being service UE 102) and retrieves its routing iinformation.Preferably, CS acts on behalf of the request of searching the identifier such as Directory Number of the VCC AS of service UE 102 (being VCC AS 158) by transmit (622) to HSS 152, determine this VCC AS application and retrieve associated routing iinformation, this request comprises the identifier of this UE.In response to receiving this request, HSS 152 returns to the VCC AS identifier of (624) asking to this CS agency.

Based on the VCC AS identifier receiving, CS agency 132 is subsequently preferably by transmitting (626) MAP PREPARE-HANDOVER-REQUEST message to VCCAS 158, this message comprises the identifier of identifier, VCC AS identifier, CS agent identifier and the target MME 134 of UE 102, asks VCC AS 158 to prepare UE 102 to hand over to packet data network 120.In response to receiving this transfer preparation request, VCC AS 158 assignments transfer numbers (HO#) and provide on VCC AS 158 operation and service UE 102 application reference number (REF#) and transmit (628) response to CS agency 132, this response is MAP PREPARE-HANDOVER-RESPONSE message preferably, and it comprises transfers number, reference number, CS agent identifier and carry out the order (HO_CMD) of switching (for making this UE access target RAN).And then CS agency 132 forwards (630) this response to MSC 118, i.e. this MAP PREPARE-HANDOVER-RESPONSE message.Alternatively, CS agency 132 can assemble and transmit another MAPPREPARE-HANDOVER-RESPONSE message to MSC 118, and this message comprises some or all information receiving from VCC AS 158 and can comprise or not comprise the reference number of reception.

In response to receiving this MAP PREPARE-HANDOVER-RESPONSE message, source MSC 118 is preferably by transmitting and have the ISUPIAM message of transferring number to MGCF/MGW 154, by switching and booting (632) to the MGCF/MGW in the territory of VCC AS, be MGCF/MGW 154, and reserve the switching of repeat circuit for communication session at this MGCF/MGW place.And then MGCF/MGW 154 is preferably by transmitting and comprise the session invitation of transferring number to VCC AS 158, preferably SIP INVITE, switches to this VCC AS notice (634).Based on this session invitation, VCC AS 158 determines that communication session is just being moved toward packet data network 120 sides of communication system 100 and is notifying (636,638) to carry out for the transfer of packet data network 120 (and particularly, for RAN 122) to the circuit-switched network 110 of communication system 100.Preferably, VCC AS 158 transmits (636) SIP PROGRESS message to MGCF/MGW154.In response to receiving this SIP PROGRESS message, MGCF/MGW 154 is by transmit ISUP IAM message to source MSC 118, transfers and carrying out and trunk has been reserved for transferring to this source MSC notice (638).

Carry out in response to the notified transfer for packet data network 120, source MSC 118 is preferably by transmitting to UE 102 switching command message that comprises VCC AS application reference number, indicate (640) this UE accessing group data network 120 via BSS 112, and access target RAN 122 particularly.In response to receiving this instruction, UE 102 is according to known technology, for example, according to 3GPP LTE standard, and more specifically, according to the standard of describing in detail in the TS of 3GPP LTE specification (technical specification) 23.401 5.3.2, access (642) RAN122 and EPC 130 and obtained by it, and RAN 122 provides communication session related service to this UE.

In response to successfully accessing RAN 122, UE 102 is by transmitting (644) session invitation via packet data network (being target RAN 122 and EPC 130) to VCC AS 158, preferably SIP INVITE, sets up via packet data network 120 and communication session remote parties.This session invitation is included in the identifier of the application of operation on VCC AS 158, i.e. reference number.VCC AS 158 is subsequently preferably by transmitting SIP 200 OK message in response to this session invitation, points out that to UE 102 (646) accept this session invitation.VCC AS 158 is further preferably via SIP 200 OK message, instruction (648) MGCF/MGW 154 for providing from the communication session of UE 102 for the link of communication session of breaking away from MSC, provides the link for branch road (611) and the CALL 1A (610) of the CALL 1B from this MSC via packet data network 120.In response to receiving this instruction, MGCF/MGW 154 this communication session of link or callings, and transmit (650) ISUP ANM to MSC 118.In response to receiving this ISUP ANM, source MSC 118 verifies that UE 102 is connected to reserved relaying, and if be like this, starts book keeping operation.And in response to receiving this ISUP ANM, MSC118 instruction (652) BSS 112 discharges the resource associated with UE 102, the i.e. branch road 612 and 613 of CALL 1B.

Now, communication session still loop by source MSC.Initialization signaling path (654～657) and bearer path (610～611) for CALL 1A and 1B retain, and are established for signaling paths (660～662) and the bearer path (663～666) of CALL 2A and 2B.; now; to route to MGCF/MGW 154 (CALL 1A) with the communication session of this remote parties from remote parties; route to source MSC 118 (branch road 611 of CALL 1B) from this MGCF/MGW; get back to this MGCF/MGW (branch road 611 of the packet data communication session of just having set up from this MSC route; be CALL 2A); and from this MGCF/MGW via packet data network 120; route to UE 102 via EPC 130 and RAN 122 (the second branch road of the packet data communication session of just having set up, i.e. CALL 2B).Communication session is from MGCF/MGW154 to MSC 118 and the route of getting back to MGCF/MGW 154, i.e. branch road 611 (CALL1B) and branch road 663 (CALL 2A), is the unwanted loop in communication session.

In order to eliminate the loop of carrying and signaling paths, VCC AS 158 is preferably by transmitting SIP RE-INVITE to MGCF/MGW 154, re-invite (668) this MGCF/MGW and participate in the communication session that involves UE 102 and CALL 1A, this SIPRE-INVITE comprises UE 102 Session Description Protocols (SDP) proposal, this SDP proposes to comprise the information of descriptive session side, the media that involve, Session ID, mark is by the circuit identification code (CIC) of the trunk channel for MSC 118 being dropped (branch road 611 of CALL 1B), with other known SDP information.Re-invite in response to receiving this session, this MGCF instruction (670) this MGW abandons the CIC of CALL 1B and further indicates this MGW, via packet data network 120, the CIC associated with CALL 1A is connected to the IP-based communication session for UE 102.MGCF/MGW 154 (particularly, this MGW) further assignment be connected to the MGW port of CALL 1A via packet data network 120 for UE 102, and preferably by transmit SIP 200 OK message to VCC AS 158, to this VCC AS notice (672) this assignment port.

VCC AS 158 further exits communication session by instruct MS C 118 and instruction MGCF/MGW 158 discharges the branch road (branch road 611 and 663) associated with CALL 1B and 2A, and arrangement removes MSC 118 from the signaling of communication session and bearer path.VCC AS 158 transmits (674,678) for a SIP BYE message of CALL 1B with for the 2nd SIP BYE message of CALL 2A to MGCF/MGW.In response to receiving a SIP BYE message, MGCF asks this MGW from the bearer path of CALL 1B, to remove the terminal of reservation, thus this MGW is removed from the bearer path of circuit-switched communication session, and further preferably by transmit ISUP RELEASE CALL 1B message to MSC 118, this MSC of request (676) discharge distributed by this MSC for communication session being routed to via circuit-switched network 110 to the link of UE 102.In response to receiving the 2nd SIP BYE message, MGCF asks this MGW to remove terminal from the bearer path of CALL 2A, thus this MGW is removed from the bearer path of the CALL 2A branch road of packet data communication session, and further preferably by transmit ISU:RELEASE CALL 2A message to MSC 118, this MSC of request (680) discharges and is allocated for the link of getting back to MGCF/MGW 154 using communication session as a part of route of CALL 2A.

In addition, VCC AS 158 is further by transmitting (682) session invitation to UE 102, preferably SIP RE-INVITE, this session invitation provides the MGW portal number with the CIC of CALL 1A and the SDP information association of CALL1A, further arranges direct connection of CALL 2B (branch road 664～666) and CALL 1A (610).In response to receiving this SIPRE-INVITE, UE 102 arranges communication session for the coupling of provided MGW portal number and sets up subsequently (664～666) via target RAN 122, EPC 130 and MGCF/MGW154 and bearer path remote parties.The signaling paths of the bearer path of CALL 1A (610) and 2B (664～666) and CALL 1A (684～685) and 2B (686) is connected now and no longer involves circuit-switched network 110, and signal flow graph 600 finishes subsequently.

By comprise CS agency 132 at packet data network 120, communication system 100 allows packet data network to communicate by letter with the VCC AS 158 of IMS 150, allow MSC 118 and the packet data network communication of circuit-switched network 110, and allow this MSC to communicate by letter with this VCC AS via packet data network, promote thus the exchange of the handover relevant information between packet data network and this VCC AS, the exchange of the handover relevant information between packet data network and circuit-switched network, and the exchange of the handover relevant information via packet data network between circuit-switched network and this VCC AS.

Although illustrate particularly and described the present invention by reference to specific embodiment of the present invention, but it should be appreciated by those skilled in the art that, under the prerequisite of the scope of the present invention of setting forth in not departing from as appended claims, can carry out various changes and its element be carried out to equivalence and replace.Therefore, specification and accompanying drawing should be regarded as illustrative and nonrestrictive, and all this changes and replace should be covered by scope of the present invention.

For specific embodiment, benefit, other advantages and the solution to problem are described above.But, this benefit, advantage, solution to problem and can draw any benefit, advantage or solution or make it become more significant any factor and should not be interpreted as crucial, the essential or basic feature of any or all claim.As term used herein " comprises " or its any version should be contained non-exclusive inclusion, process, method, article or the equipment that comprises thus element list not only comprise these elements and also can comprise clearly do not list or be other intrinsic elements for this process, method, article or equipment.As term used herein " comprises " and/or " having " is defined as comprising.And, unless pointed out in addition herein, otherwise, such as first and second, the use of the relation property term of top and bottom etc., if any, unique for making an entity or action be different from another entity or action, there is no need require or mean such entity action between any reality such relation or order.The in the situation that of more restriction not, before with the element of " ", do not get rid of the existence of the extra identical element in this process, method, article or equipment.

Claims (10)

1. the method for switching between communication system communication session technology, described communication system comprise can with the internet protocol multi-media sub-system of communications of user equipment (IMS), described method comprises:

Transmit forward link session service and receive reverse link session service from described subscriber equipment to subscriber equipment via packet data network;

Determine and switch described communication session;

In response to determining, described communication session is switched to circuit-switched network, transmits the information about the target mobile switching centre of described circuit-switched network by the circuit switching agency of described packet data network to described subscriber equipment;

Transmit Target Cell Identifier and mobile switching centre's mark by described subscriber equipment and via described packet data network to the application server for continuity of voice call of described IMS;

Acted on behalf of via the described circuit switching of described packet data network by described application server for continuity of voice call, indicate described target mobile switching centre to prepare to transfer;

Continue described Session Anchor in described application server for continuity of voice call;

Obtain described subscriber equipment by the subsystem of objective base station associated with described target mobile switching centre; With

Provide communication session service by described subsystem of objective base station to described subscriber equipment.

2. the method for claim 1, further comprises: transmitted and transfer relevant information to described application server for continuity of voice call via described circuit switching agency by described mobile switching centre.

3. the method for claim 1, is wherein exchanging MAP message between described application server for continuity of voice call and described circuit switching agency and between described circuit switching agency and described target mobile switching centre.

4. the method for claim 1, further comprises: by described application server for continuity of voice call via described packet data network to described notification of user equipment resource assignation to described subscriber equipment in described circuit-switched network.

5. the method for claim 1, further comprises:

Notify described circuit-switched network to obtain described subscriber equipment via described circuit switching agency to described application server for continuity of voice call by described subsystem of objective base station; With

In response to the notice that receives described circuit-switched network and obtained described subscriber equipment, arrange the resource in described packet data network to discharge by described application server for continuity of voice call via described circuit switching agency.

6. the method for switching between communication system service technology, described communication system comprise can with the internet protocol multi-media sub-system of communications of user equipment (IMS), described method comprises:

Transmit forward link service business and receive reverse link service business from described subscriber equipment to subscriber equipment via circuit-switched network;

Determine and switch communication session;

Switch described communication session in response to determining, transmit to the mobile switching centre of described circuit-switched network the request that described communication session is switched to packet data network by the base station sub-system of described circuit-switched network;

In response to the request that receives described switching, act on behalf of to the circuit switching of described packet data network the request that transmission preparations are switched by described mobile switching centre;

By the application server for continuity of voice call exchanging handover information of described circuit switching agency and internet protocol multi-media sub-system;

Provide by described circuit switching agency the handover information receiving from described application server for continuity of voice call to described mobile switching centre;

Continue described Session Anchor in described application server for continuity of voice call;

Indicate described subscriber equipment to access described packet data network by described circuit-switched network;

Obtain described subscriber equipment by the radio access network of described packet data network; With

Provide service by described packet data network to described subscriber equipment.

7. method as claimed in claim 6, further comprises following one or more step that removes:

Remove described mobile switching centre one or more from following: the bearer path of described communication session and the signaling paths of described communication session, and

After the described radio access network of described packet data network obtains described subscriber equipment, remove the loop in the described communication session between described mobile switching centre and gateway.

8. method as claimed in claim 6, wherein MAP message is used to one or more in following step: the request that transmission preparations are switched is acted on behalf of to circuit switching by described mobile switching centre, and described circuit switching agency and described application server for continuity of voice call exchanging handover information.

9. method as claimed in claim 6, wherein said circuit switching agency comprises with the step of described application server for continuity of voice call exchanging handover information: in response to the request that receives described preparation switching, carry out following one or more step:

Acted on behalf of the application of the application server for continuity of voice call of definite and described user device association by described circuit switching; With

Prepare to switch described subscriber equipment by application server for continuity of voice call described in described circuit switching proxy requests.

10. method as claimed in claim 6, wherein provides the step of the handover information receiving from described application server for continuity of voice call to comprise by described circuit switching agency to described mobile switching centre: between described application server for continuity of voice call and described circuit switching agency and between described circuit switching agency and described mobile switching centre, exchange MAP message.