WO2009015601A1 - Procédé assurant la continuité des appels et dispositif correspondant - Google Patents

Procédé assurant la continuité des appels et dispositif correspondant Download PDF

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Publication number
WO2009015601A1
WO2009015601A1 PCT/CN2008/071799 CN2008071799W WO2009015601A1 WO 2009015601 A1 WO2009015601 A1 WO 2009015601A1 CN 2008071799 W CN2008071799 W CN 2008071799W WO 2009015601 A1 WO2009015601 A1 WO 2009015601A1
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WIPO (PCT)
Prior art keywords
access network
call
network
handover
multimode terminal
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Application number
PCT/CN2008/071799
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English (en)
French (fr)
Inventor
Zhaohui Zhang
Dongming Zhu
Hengliang Zhang
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Huawei Technologies Co., Ltd.
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Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Publication of WO2009015601A1 publication Critical patent/WO2009015601A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • H04W36/1446—Reselecting a network or an air interface over a different radio air interface technology wherein at least one of the networks is unlicensed

Definitions

  • the present invention relates to the field of communications, and in particular, to a method and apparatus for implementing call continuity. Background technique
  • Voice Call Continuity is a service provided by the IMS (IP Multimedia Subsystem) network to which the user belongs, enabling the user's voice call to be between the circuit domain (CS domain) and the IMS network. Perform a two-way switch.
  • the converged IMS architecture enables seamless voice call services in the CS domain and IP-Connectivity Access Network IP-CAN (such as various IEEE 802 series wireless packet access networks). It can reduce the load on the wireless resources of GSM/UMTS (Global System for Mobile communication, Universal Mobile Telecommunications System, Universal Mobile Telecommunications System) and increase the revenue of operators.
  • GSM/UMTS Global System for Mobile communication, Universal Mobile Telecommunications System, Universal Mobile Telecommunications System
  • the VCC user initiated or received call is anchored to the domain switching function entity DTF of the IMS network to which the user belongs.
  • the DTF is an application server with the B2BUA (Back-to-Back User Agent) function.
  • B2BUA Back-to-Back User Agent
  • the access leg the session between the DTF and the VCC UE
  • the remote leg the session between the DTF and the remote user
  • Switching is to use a new access leg cut alternative network connected to the distal end and the leg cut out the old network access l eg.
  • the VCC terminal can accurately sense the strength of the wireless signals of each access network than the core network. Therefore, the domain handover process with higher delay requirements is initiated by the terminal to the network.
  • the destination network calls a special number (establishing a new access leg).
  • the DTF process can be reached by the number call request, and the DTF can determine the domain switch request and the direction of the handover accordingly.
  • the call in the switching source network is released by the DTF or VCC terminal (release the old access leg). This completes the replacement of the two access legs so that the user's voice call is switched to the destination network.
  • Figure 1 shows the flow of a call from the IMS to the CS domain in the VCC, including the following steps (some of the non-critical processes in the middle have been omitted; some of the entities described by the remote UE are also omitted):
  • the VCC UE determines that the call needs to be switched to the CS domain according to the wireless environment, and the domain name is switched in the CS domain calling VDN (VCC domain transfer number).
  • VMSC Voice Mobile Switching Centre
  • CAMEL Customerised Applications for Mobile Networks Enhanced Logic
  • the DTF determines the domain switching request destination domain information according to the number in the INVITE.
  • the anchored session is located based on the calling information.
  • the DTF proxy user and the remote user re-negotiate the media of the far leg (DTF to remote UE) using the media information in the handover request.
  • the DTF releases the VCC user's access part of the call resource in the CS domain (which may also be a terminal-initiated release, where the DTF release in the network is taken as an example).
  • multimode terminals exist in the case of single radio and dual radio. That is, the terminal supports two or more access network technologies, but cannot support communication under a specific two access technologies at the same time, and the terminal is said to be a single wireless for the two access technologies;
  • the above access network technology can simultaneously support communication under a specific two access technologies, and the terminal is said to be dual wireless for the two access technologies.
  • the multimode terminal When a multimode terminal performs call handover, the multimode terminal arbitrarily selects an available handover destination access network, so that there may be a dual wireless relationship between the handover destination access network and the original access network, but it may also be a single wireless relationship. .
  • the connection in the original access network can be interrupted first, and then the connection in the destination network is switched, so that the user's service will be inevitably interrupted. Therefore, in the prior art, when a multimode terminal performs call handover, the continuity of the call cannot be guaranteed. Summary of the invention
  • Embodiments of the present invention provide a method and apparatus for implementing call continuity, so as to ensure continuity of a call when a multimode terminal performs call handover.
  • the method of the embodiment of the present invention includes: when a multimode terminal makes a call in the first access network, detecting that a handover will occur; the multimode terminal is in an access network that has a dual wireless relationship with the first access network according to the handover policy. And selecting a currently available third access network; and the multimode terminal switching the call in the first access network to the third access network.
  • a multimode terminal includes: a detecting unit, configured to detect whether a handover will occur when the multimode terminal makes a call in the first access network, and issue a trigger signal when a handover occurs a switching policy saving unit, configured to save a switching policy; a selecting unit, configured to use a trigger signal sent by the detecting unit as a trigger condition, and according to the switching policy saved by the switching policy holding unit, from the first access network, there is a dual wireless In the access network of the relationship, a third access network that is currently available is selected; and a switching unit is configured to switch the call in the first access network to the third access network.
  • the method for implementing call continuity provided by the embodiment of the present invention is that, when a multi-mode terminal performs a call in the first access network, when a handover is detected, the destination switching network is not arbitrarily selected, but according to the handover policy. From the access network having a dual wireless relationship with the first access network, a currently available third access network is selected, and the call in the first access network is switched to the third access network. Therefore, when the multi-mode terminal performs call handover, the continuity of the call is ensured.
  • the embodiment of the present invention further provides a multi-mode terminal, including: a detecting unit, a switching policy holding unit, a selecting unit, and a switching unit, corresponding to the method for implementing call continuity provided by the embodiment of the present invention.
  • 1 is a flow chart of a call from an IMS to a CS domain in an existing VCC; 2 is a flow chart of steps of a method according to an embodiment of the present invention;
  • FIG. 3 is a schematic structural diagram of a multimode terminal according to an embodiment of the present invention.
  • FIG. 5 is a flowchart of Embodiment 2 of the present invention.
  • FIG. 6 is a flowchart of Embodiment 3 of the present invention.
  • FIG. 7 is a flowchart of Embodiment 4 of the present invention.
  • FIG. 8 is a flowchart of Embodiment 5 of the present invention.
  • FIG. 9 is a flow chart of Embodiment 6 of the present invention. detailed description
  • the embodiment of the present invention provides a method and a multi-mode terminal for implementing call continuity.
  • the first access network and the second access network in the embodiment of the present invention are in a single wireless relationship, and the third access network and the first access network and the second access network are both in a dual wireless relationship, and are not further described below.
  • a method for implementing call continuity provided by an embodiment of the present invention, as shown in FIG. 2, includes the following main steps:
  • the multimode terminal when the multimode terminal detects at least one of the following conditions, it is determined that the handover is detected: the detected call is about to lose the connection in the first access network; the current service quality of the detected call is lower than the previous The threshold value is set; the switching operation indication of the user is detected; and the access network having the communication tariff lower than the first access network is detected.
  • the multimode terminal selects a currently available third access network from the access network that has a dual wireless relationship with the first access network according to the handover policy.
  • the multimode terminal switches the call in the first access network to the third access network.
  • the switching policy stored in the multimode terminal can be set or updated by the network operator or the user. If the handover policy requires that the call is switched to a second access network that has a single wireless relationship with the first access network, the multimode terminal has a dual wireless relationship from both the first access network and the second access network. In the access network, selecting a currently available third access network; and switching the call in the first access network to the third access network, and then switching the call from the third access network to the second Access to the network.
  • the third access network that belongs to the same operator as the first access network may be preferred; and/or preferably the second access network belongs to the same operator. Access Network.
  • the embodiment of the present invention further provides a multimode terminal.
  • the method includes: a detecting unit, a switching policy saving unit, a selecting unit, and a switching unit.
  • the detecting unit 1 is configured to detect whether a handover will occur when the multimode terminal makes a call in the first access network, and issue a trigger signal when the handover occurs. Specifically, the detecting unit 1 detects at least one of the following situations, and determines that detecting that a handover will occur: detecting that the call is about to lose connectivity in the first access network; detecting that the current quality of service of the call is lower than preset Threshold value; detecting a handover operation indication of the user; detecting that the communication tariff is lower than the access network of the first access network.
  • the switching policy saving unit 3 is configured to save the switching policy.
  • the switching policy saved in the switching policy holding unit 3 is set or updated by the network operator or the user, and the switching policy includes, but is not limited to: switching to the switching policy of the access network that is in the dual wireless relationship with the current access network.
  • a handover policy of the transit handover preferably a handover policy with a third access network of the first access network belonging to the same operator, and/or preferably a second access network with the same access network belonging to the same operator Switching strategy.
  • the selecting unit 4 is configured to use the trigger signal sent by the detecting unit 1 as a triggering condition, and select one according to the switching policy saved by the switching policy holding unit 3 from the access network having a dual wireless relationship with the first access network.
  • the third access network currently available.
  • the switching unit 2 is configured to switch the call in the first access network to the third access network.
  • the selection unit 4 from the first access network and the second access In the access network where the network has dual wireless relationship, the third access network currently available is selected; after the switching unit 2 switches the call to the third access network, the call is transferred from the third access network. Switch to the second access network.
  • the call in the first access network (the WLAN1 network) is directly switched to the third access network.
  • the WLAN 2 network is used as an example, and other eligible IP-CAN networks may also be used. WiMAX, etc.). See Figure 4, including the following steps:
  • the multimode terminal detects that the handover is about to occur, and selects, according to the handover policy, the WLAN 2 access network that belongs to the same WLAN 1 network as the handover destination network from the access network that has the dual wireless relationship with the WLAN1 network;
  • the multimode terminal initiates a multimedia call handover process in the WLAN2 network.
  • a typical WLAN network or a 3G high-bandwidth IPC AN network is hot-covered at the beginning of the network deployment, that is, its coverage is very small compared to the mature 2G/3G CS, PS and other wide coverage.
  • the multimode terminal chooses to use the WLAN network or IPCAN network as the final handover destination access network, especially for mobile users, the duration of the call on the WLAN network or IPCAN network will be short. Therefore, the switching policy saved in the multimode terminal may be preset by the network operator or the user.
  • the switching destination access network selected by the multimode terminal satisfies the switching policy of the transit switching, the third access network is required according to the requirements of the switching policy.
  • the switched transit network the call in the first access network is further switched to the widely covered second access network.
  • the multimode terminal detects that the communication tariff is lower than the second access network of the first access network, and requires the call to be switched to the second access network; and the user also indicates that the user switches to the second connection according to his own preference.
  • the multimode terminal has already conducted a multimedia session with the remote UE in the first access network (3G CS network), and the anchoring is completed at the DTF.
  • the third access network (in the embodiment, the WLAN access network is taken as an example, or other eligible IP-CAN access networks, such as WiMAX, etc.) may be switched to the second access network after the transit (2G CS). Network), to avoid the degradation of CS multimedia calls.
  • 2G CS the following steps are included:
  • the multimode terminal detects that the handover is about to be initiated, and the determined final handover destination network (2G CS network) will require the CS multimedia call to degrade and interrupt the user's service (ie, the 2G CS network and the 3G CS network have a single wireless relationship).
  • the multimode terminal detects that it can currently access the WLAN network or IPCAN network that supports the multimedia call.
  • the multimode terminal selects a WLAN network having a dual wireless relationship with the 3G CS network as a third access network for relaying the multimedia call according to the handover policy.
  • the multimode terminal initiates a handover request in the WLAN network to switch the multimedia call to the WLAN network.
  • the multimode terminal continues to switch according to the handover policy.
  • the multimode terminal initiates a handover request carrying a voice component in the 2G CS network, and the DTF receives the voice component to the 2G CS network after receiving.
  • the voice component of the multimedia call is switched to the third access network in the first access network due to the transit of the third access network in a dual wireless relationship with the first access network and the second access network. And in the process of switching the third access network to the second access network, the quality is not degraded, so the user does not feel the change of the voice quality during the entire call, and also ensures the continuity of the voice call. Give users a better experience.
  • the multimode terminal has made a voice call with the remote UE in the first access network (3G PS network), and the anchoring is completed in the DTF. After the call is forwarded through the new session of the third access network or the existing session, the call is switched to the second access network (2G CS network).
  • the third access network uses WLAN as an example, and may also be other IP-CANs, such as WiMAX.
  • the single radio switch that can be applied to the embodiment of the present invention further includes 2G CS switching to 3G PS, and LTE switching to 3G CS. Or 2G CS or the like; the media component in this embodiment is not limited to a voice call, and may also be other media components. See Figure 6, which includes the following steps:
  • the multimode terminal detects that the handover is about to be initiated, and determines the final handover destination network (2G CS network). A single wireless relationship with the 3G PS network where the call is currently located will interrupt the user's service.
  • the multimode terminal detects that it can currently access the WLAN network or IP-CAN network that supports voice calls.
  • the multimode terminal selects a WLAN network having a dual wireless relationship with the 3G PS network according to the handover policy as the third access network for relaying the voice call.
  • the multimode terminal initiates a handover request in the WLAN network, and switches the voice call to the WLAN network (if switching to a new session in the WLAN network, the SIP INVITE is used to initiate the handover; if switching to the existing session in the WLAN network) , then use RelNVITE to initiate a switch on the target session).
  • the handover is continued according to the handover policy.
  • the multimode terminal initiates a handover request carrying a voice component in the 2G CS network, and the DTF receives the voice component to the 2G CS network after receiving.
  • the transit of the third access network that is in a dual wireless relationship with the first access network and the second access network Since the transit of the third access network that is in a dual wireless relationship with the first access network and the second access network, the first access network and the second access network having a single wireless relationship are avoided.
  • the service interruption caused by voice switching brings a better experience to the user.
  • the multimode terminal has performed a voice session with the remote UE in the first access network (2G CS network), and has performed a video session in the third access network (WLAN network), and both are in the DTF.
  • the anchoring is completed.
  • the multimode terminal switches the voice session to the WLAN network, it merges with the video session and then switches the merged session to the second access network (3G PS network).
  • the third access network uses WLAN as an example, and may also be other IP-CANs, such as WiMAX.
  • the single radio switch that can be applied to the embodiment of the present invention further includes 2G CS switching to 3G PS, and LTE switching to 3G CS. Or 2G CS or the like; the media component in this embodiment is not limited to a voice call, and may also be other media components. See Figure 7, which includes the following steps:
  • the multimode terminal detects that the handover is about to be initiated, and the determined final handover destination network (3G PS network) and the 2G CS network where the voice session is currently located have a single wireless relationship, which will interrupt the user's voice service.
  • the multimode terminal detects that it can currently access the WLAN network or IPCAN network that supports the voice session.
  • the multimode terminal selects a WLAN network that has a dual wireless relationship with the 2G CS network according to the handover policy.
  • the multimode terminal initiates a handover request in an existing video session in the WLAN, switches the voice session to the WLAN network, and merges the video session and the voice session into a multimedia session.
  • the handover is continued according to the handover policy.
  • the multimode terminal initiates switching of multimedia components in the 3G PS network, and switches the multimedia session to the 3G PS network.
  • the multimode terminal has performed a voice session with the remote UE in the first access network (3G PS), and has performed a video session in the third access network (WLAN network), and both are completed in the DTF. Anchored. After the multimode terminal switches the voice session to the WLAN network, it will be combined with the video session. After the call is transferred through the third access network, the video component is switched to the second access network (2G PS network).
  • the third access network uses WLAN access as an example, and may also be other IP-CAN access, such as WiMAX.
  • the single radio switch that can be applied to the embodiment of the present invention also includes 2G CS switching to 3G PS, LTE. Switching to 3G CS or 2G CS, etc.; the media component in this embodiment is not limited to a voice call, but may be other media components. See Figure 8, which includes the following steps:
  • the multimode terminal detects that the handover is about to be initiated, and determines the final handover destination network (2G PS network) and the 3G PS network where the voice session is currently located as a single wireless relationship, which will interrupt the user's voice service.
  • the multimode terminal detects that it can currently access the WLAN network or IPC AN network that supports voice calls.
  • the multimode terminal selects a WLAN network having a dual wireless relationship with the 3G PS network according to the handover policy as a third access network for relaying the voice call.
  • the multimode terminal initiates a handover in an existing video session in the WLAN network, requesting that the voice components of the first access network be merged.
  • the handover is continued according to the handover policy.
  • the multimode terminal initiates a handover request carrying a video component in the 2G PS network, and the DTF receives the video component to the 2G PS network after receiving.
  • the process of setting or updating the handover policy by the operator In this embodiment, only the device management mechanism is used as an example, and the other handover policies, such as the policy of switching the same carrier network, may also be used.
  • the program to set or update Referring to Figure 9, the following steps are included:
  • the switching management entity in the network advertises the switching policy information (here, the switching policy of the transit switching as an example) to the multimode terminal through device management (DM).
  • the switching policy information here, the switching policy of the transit switching as an example
  • the multimode terminal determines that the handover policy is received for the first time, and then saves; otherwise, the corresponding handover policy is updated.
  • the multimode terminal can also provide the user with an interface to set and update the switching policy.
  • the method for implementing call continuity provided by the embodiment of the present invention, when a multi-mode terminal performs a call in the first access network, detects that a handover will occur, and does not arbitrarily select a destination switching network. According to the handover policy, selecting a currently available third access network from the access network having a dual wireless relationship with the first access network, and switching the call in the first access network to the third access network . Therefore, when the multi-mode terminal performs call handover, the continuity of the call is guaranteed.
  • the embodiment of the present invention further provides a multi-mode terminal, including: a detecting unit, a switching policy holding unit, a selecting unit, and a switching unit, corresponding to the method for implementing call continuity provided by the embodiment of the present invention.
  • the embodiment of the present invention proposes a scheme for transit switching through the third access network, so that the call interruption caused by the single radio environment to the handover process can be avoided, and the service experience of the user is improved. Specifically, because the transit of the third access network that is in a dual wireless relationship with the first access network and the second access network, the call interruption caused by the CS multimedia call degradation process to the user during handover is avoided.
  • the switching policy saved in the multimode terminal may be set or updated by the network operator or the user.
  • the switch may select an access network that belongs to the same carrier as the current call network according to the handover policy, thereby improving the network usage rate of the operator. Improve the revenue of operators.

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Description

一种实现呼叫连续性的方法及装置 技术领域
本发明涉及通信领域， 特别是涉及一种实现呼叫连续性的方法及装置。 背景技术
语音呼叫连续 （Voice Call Continuity VCC ) 是在用户归属的 IMS ( IP Multimedia Subsystem, IP多媒体子系统） 网络提供的一种业务， 能够使用户的 语音呼叫在电路域（CS域）和 IMS网络之间进行双向切换。 融合的 IMS架构 使在 CS域和 IP连接接入网 ( IP-Connectivity Access Network IP-CAN ) (比如 各种 IEEE 802系列的无线分组接入网等） 下实现无缝的语音呼叫服务， 不但可 以减轻 GSM/UMTS ( Global System for Mobile communication, 全球移动通信系 统； Universal Mobile Telecommunications System, 通用移动远程通信系统)无线 资源的负荷， 还可增加运营商的收益。
为了能进行域切换， VCC用户发起的或接收的呼叫都要锚定到该用户归属 的 IMS网络的域切换功能实体 DTF。 DTF是具有 B2BUA ( Back-to-Back User Agent背靠背用户代理）功能的应用服务器。 在 VCC中， DTF和 VCC UE之间 的会话叫做 access leg (接入腿 ), DTF和远端用户间的那段会话叫做 remote leg (远端腿）。 切换就是使用切入网络中新的 access leg替换和远端腿相连的切出 网络中旧的 access leg。一般情况下 VCC终端比核心网络更能准确感知各接入网 络无线信号的强弱， 故对于时延要求较高的域切换过程都是由终端到网络的方 向发起。
当用户的 VCC终端检测到无线信号等因素判断需要从源网络切换到目的网 络时， 在目的网络呼叫一个特殊的号码（建立新接入腿）。 通过该号码呼叫请求 可以到达 DTF处理， DTF据此可以确定是域切换请求， 以及切换的方向。 根据 VCC终端在新建立呼叫中支持的媒体信息和原呼叫的远端用户终端间重新协商 媒体， 以实现媒体流改向 （更新远端腿以替换旧的接入腿）。 完成媒体协商以及 新的呼叫建立后， 此时由 DTF或者 VCC终端释放切换源网络中的呼叫 （释放 旧接入腿）。 这样完成两个接入腿的替换， 从而用户的语音呼叫就切换到了目的 网络。
图 1是 VCC中呼叫从 IMS切换到 CS域的流程， 包括下列步骤（中间的一 些非关键流程已经省略； 远端 UE所述的部分实体也省略了 ):
1 , VCC UE根据无线环境判断呼叫需要切换到 CS域，在 CS域呼叫特殊号 码 VDN ( VCC domain transfer number VCC域切换号码）起域切换。
2, VMSC ( Visited Mobile Switching Centre, 拜访地移动交换中心）根据 CAMEL ( Customised Applications for Mobile networks Enhanced Logic, 移动网络 增强逻辑的定制化应用）业务过程将呼叫改向为 IMS网络 DTF的 PSI号码， 故 呼叫可以路由到 VCC用户归属 IMS网络的 DTF处理。
3 , DTF根据 INVITE中的号码确定域切换请求目的域信息。 并根据主叫信 息定位锚定的会话。
4-8 , DTF 代理用户和远端用户使用切换请求中的媒体信息重协商远端腿 ( DTF到 remote UE ) 的媒体。
9, 在目的网络的会话建立完成后， DTF释放 VCC用户在 CS域中的接入 部分呼叫资源 （也可以是终端发起的释放， 此处以网络中的 DTF释放为例；)。
发明人在发明过程中发现，多模终端存在单无线（ single radio )和双无线（ dual radio ) 的情况。 即该终端支持两种以上的接入网络技术， 但不能同时支持特定 的两种接入技术下的通信， 则称该终端对于这两种接入技术属于单无线的情况； 该终端支持两种以上的接入网络技术， 并能同时支持特定的两种接入技术下的 通信， 则称该终端对于这两种接入技术属于双无线的情况。
多模终端进行呼叫切换时， 由多模终端随意选择可用的切换目的接入网络， 这样切换目的接入网络与原有接入网络之间有可能是双无线关系， 但也有可能 是单无线关系。 当多模终端在单无线关系的接入技术网络间进行呼叫切换时， 只能先中断原有接入网络中的连接， 再建立切换目的接入网中的连接， 这样用 户的业务将出现不可避免的中断。 所以现有技术在多模终端进行呼叫切换时， 不能保证呼叫的连续性。 发明内容
本发明实施例提供一种实现呼叫连续性的方法及装置， 以实现在多模终端 进行呼叫切换时， 保证呼叫的连续性。
本发明实施例的方法包括： 多模终端在第一接入网络中进行呼叫时， 检测 到将发生切换； 多模终端根据切换策略， 从与第一接入网络存在双无线关系的 接入网络中， 择一当前可用的第三接入网络； 以及多模终端将第一接入网络中 的呼叫切换到第三接入网络。
本发明实施例的一种多模终端， 包括： 检测单元， 用于在该多模终端在第 一接入网络中进行呼叫时， 检测是否将发生切换， 并在将发生切换时， 发出触 发信号； 切换策略保存单元， 用于保存切换策略； 选择单元， 用于以收到检测 单元发出的触发信号作为触发条件， 根据切换策略保存单元保存的切换策略， 从与第一接入网络存在双无线关系的接入网络中， 择一当前可用的第三接入网 络； 切换单元， 用于将第一接入网络中的呼叫切换到第三接入网络。
本发明实施例提供的实现呼叫连续性的方法， 由于多模终端在第一接入网 络中进行呼叫的过程中， 检测到将发生切换时， 不是任意选择目的切换网络， 而是根据切换策略， 从与第一接入网络存在双无线关系的接入网络中， 择一当 前可用的第三接入网络， 并将第一接入网络中的呼叫切换到第三接入网络。 所 以在多模终端进行呼叫切换时， 保证了呼叫的连续性。 本发明实施例还提供了 一种多模终端， 包括： 检测单元、 切换策略保存单元、 选择单元和切换单元， 与本发明实施例提供的实现呼叫连续性的方法相对应。 附图说明
图 1为现有 VCC中呼叫从 IMS切换到 CS域的流程图； 图 2为本发明实施例的方法步骤流程图；
图 3为本发明实施例的多模终端结构示意图；
图 4为本发明实施例 1的流程图；
图 5为本发明实施例 2的流程图；
图 6为本发明实施例 3的流程图；
图 7为本发明实施例 4的流程图；
图 8为本发明实施例 5的流程图；
图 9为本发明实施例 6的流程图。 具体实施方式
为了实现在多模终端进行呼叫切换时， 保证呼叫的连续性， 本发明实施例 提供了一种实现呼叫连续性的方法和多模终端。 本发明实施例中的第一接入网 络与第二接入网络是单无线关系， 第三接入网络与第一接入网络和第二接入网 络均为双无线关系， 以下不再赘述。
本发明实施例提供的一种实现呼叫连续性的方法， 参见图 2 所示， 包括下 列主要步骤：
51、 多模终端在第一接入网络中进行呼叫时， 检测到将发生切换。
本发明实施例中多模终端至少检测到下述情况之一， 则判定为检测到将发 生切换： 检测到呼叫在第一接入网中即将失去连接； 检测到呼叫当前的服务质 量低于预先设置的门限值； 检测到用户的切换操作指示； 检测到存在通信资费 低于第一接入网络的接入网络。
52、 多模终端根据切换策略， 从与第一接入网络存在双无线关系的接入网 络中， 择一当前可用的第三接入网络。
S3、 多模终端将第一接入网络中的呼叫切换到第三接入网络。
进一步， 可由网络运营者或者用户设置或更新保存在多模终端中的切换策 略。 若切换策略要求将所述呼叫切换到与第一接入网络存在单无线关系的第二 接入网络时， 多模终端从与第一接入网络和第二接入网络均存在双无线关系的 接入网络中， 择一当前可用的第三接入网； 并将第一接入网络中的呼叫切换到 第三接入网络后， 再将该呼叫从第三接入网络中转切换到第二接入网络。
网络运营者或者用户设置或更新切换策略时， 可优选与第一接入网络归属 于同一运营商的第三接入网络； 和 /或优选与第一接入网络归属于同一运营商的 第二接入网。
本发明实施例还提供了一种多模终端， 参见图 3所示， 其包括： 检测单元、 切换策略保存单元、 选择单元和切换单元。
检测单元 1 , 用于在该多模终端在第一接入网络中进行呼叫时，检测是否将 发生切换， 并在将发生切换时， 发出触发信号。 具体的， 检测单元 1 至少检测 到下述情况之一， 则判定为检测到将发生切换： 检测到呼叫在第一接入网中即 将失去连接； 检测到呼叫当前的服务质量低于预先设置的门限值； 检测到用户 的切换操作指示； 检测到存在通信资费低于第一接入网络的接入网络。
切换策略保存单元 3 , 用于保存切换策略。 具体的， 切换策略保存单元 3中 保存的切换策略， 由网络运营者或者用户设置或更新， 切换策略包括但不限于： 切换到与当前所在接入网是双无线关系的接入网的切换策略， 中转切换的切换 策略， 优选与第一接入网络归属于同一运营商的第三接入网络的切换策略， 和 / 或优选与第一接入网络归属于同一运营商的第二接入网的切换策略。
选择单元 4 , 用于以收到检测单元 1发出的触发信号作为触发条件，根据切 换策略保存单元 3保存的切换策略， 从与第一接入网络存在双无线关系的接入 网络中， 择一当前可用的第三接入网络。
切换单元 2 , 用于将第一接入网络中的呼叫切换到第三接入网络。
若切换策略保存单元 3保存的切换策略要求将所述呼叫切换到与第一接入 网络存在单无线关系的第二接入网络， 则选择单元 4从与第一接入网络和第二 接入网络均存在双无线关系的接入网络中， 择一当前可用的第三接入网； 切换 单元 2将所述呼叫切换到第三接入网络后， 再将该呼叫从第三接入网络中转切 换到第二接入网络。 以下通过 6个实施例具体描述。
[实施例 1] 将第一接入网络（ WLAN1网络）中的呼叫直接切换到第三接入 网络（本实施例中，以 WLAN2网络为例，也可是其它符合条件的 IP-CAN网络， 如 WiMAX等）。 参见图 4所示， 包括下列步骤：
1 , 多模终端检测到即将发生切换， 根据切换策略， 从与 WLAN1网络存在 双无线关系的接入网络中选择和 WLAN1 网络同属于一个运营者的 WLAN2接 入网络作为切换目的网络；
2, 多模终端在 WLAN2网络中发起多媒体呼叫的切换过程。
一般的 WLAN网络或者 3G的高带宽的 IPC AN网络在网络部署初期都是热 点覆盖， 即其覆盖范围和成熟的 2G/3G CS, PS等广覆盖相比非常小。 若多模终 端选择以 WLAN网络或者 IPCAN网络作为最终的切换目的接入网络， 尤其对 于移动着的用户， 呼叫在 WLAN网络或者 IPCAN网络可持续的时间会很短。 因此可由网络运营者或者用户预先设置保存在多模终端中的切换策略， 当多模 终端选择的切换目的接入网络满足中转切换的切换策略时， 根据切换策略的要 求， 将第三接入网络作为切换的中转网络， 进一步将第一接入网络中的呼叫切 换到广覆盖的第二接入网络。
存在多模终端检测到通信资费低于第一接入网络的第二接入网络， 并要求 将呼叫切换到第二接入网络的需求； 还存在用户根据自己的偏好， 指示切换到 第二接入网络的需求。 因此可由网络运营者或者用户预先设置保存在多模终端 中的切换策略， 根据切换策略的要求， 将第三接入网络作为切换的中转网络， 进一步将第一接入网络中的呼叫切换到第二接入网络， 以满足用户的需求。 以 下实施例描述这种情况。
[实施例 2] 多模终端已经和远端 UE在第一接入网络（3G CS网络） 中进 行了多媒体会话，并在 DTF完成了锚定。第三接入网络（本实施例中，以 WLAN 接入网络为例， 也可是其它符合条件的 IP-CAN接入网络， 如 WiMAX等）中转 后部分媒体切换到第二接入网络（2G CS网络）， 避免 CS多媒体呼叫的降质。 参见图 5所示， 包括下列步骤：
1 , 多模终端检测到即将发起切换， 确定的最终切换目的网络（2G CS网络） 将要求 CS多媒体呼叫降质而中断用户的业务（即 2G CS网络与 3G CS网络存 在单无线关系）。
此时多模终端检测到当前可以接入到支持多媒体呼叫的 WLAN 网络或 IPCAN 网络。 多模终端根据切换策略选择与 3G CS 网络存在双无线关系的 WLAN网络作为中转切换该多媒体呼叫的第三接入网络。
2,多模终端在 WLAN网络中发起切换请求，将多媒体呼叫切换到了 WLAN 网络中。
3 , 多模终端在上述切换完成后 （如媒体已经转移到了 WLAN 网络中且多 模终端和 3G CS网络的所有连接已经释放 ), 根据切换策略继续切换。
4, 多模终端在 2G CS网络中发起携带有语音成分的切换请求， DTF收到后 将语音成分切换到 2G CS网络。
由于通过与第一接入网络和第二接入网络均为双无线关系的第三接入网络 的中转， 所以所述多媒体呼叫的语音成分， 在第一接入网络切换到第三接入网 络， 以及在第三接入网络切换到第二接入网络的过程中， 均未降质， 所以用户 在整个呼叫过程中不会感觉到语音质量的变化， 而且也保证了语音呼叫的连续 性， 给用户带来了更好的体验。
[实施例 3] 多模终端已经和远端 UE在第一接入网络（ 3G PS网络 )中进行 了语音呼叫， 并在 DTF完成了锚定。 呼叫经第三接入网络的新会话或既有会话 中转后， 切换到第二接入网络（2G CS 网络）。 本实施例中， 第三接入网络以 WLAN为例， 也可是其它 IP-CAN, 如 WiMAX等； 可以应用本发明实施例的 single radio切换还包括 2G CS 切换到 3G PS、LTE切换到 3G CS或者 2G CS等； 本实施例中媒体成分不限于语音呼叫， 也可以是其它或多种媒体成分。 参见图 6 所示， 包括下列步骤：
1 , 多模终端检测到即将发起切换， 确定的最终切换目的网络（2G CS网络） 与呼叫当前所在的 3G PS网络为单无线关系， 将中断用户的业务。
此时多模终端检测到当前可以接入到支持语音呼叫的 WLAN 网络或 IP-CAN 网络。 多模终端根据切换策略选择与 3G PS 网络存在双无线关系的 WLAN网络作为中转切换该语音呼叫的第三接入网络。
2,多模终端在 WLAN网络中发起切换请求，将该语音呼叫切换到了 WLAN 网络中 （若切换到 WLAN网络中的新会话， 则使用 SIP INVITE发起切换； 若 切换到 WLAN网络中的既有会话， 则在目标会话上使用 RelNVITE发起切换）。
3 , 多模终端检测到上述切换完成后 （如媒体已经转移到了 WLAN 网络中 且多模终端和 3G PS网络的所有连接已经释放）， 根据切换策略继续切换。
4, 多模终端在 2G CS网络中发起携带有语音成分的切换请求， DTF收到后 将语音成分切换到 2G CS网络。
由于通过与第一接入网络和第二接入网络均为双无线关系的第三接入网络 的中转， 所以避免了存在单无线关系的第一接入网络与第二接入网络之间的语 音切换导致的业务中断， 给用户带来了更好的体验。
[实施例 4] 多模终端已经和远端 UE在第一接入网络（ 2G CS网络）中进行 了语音会话， 在第三接入网络（WLAN网络） 中进行了视频会话， 并都在 DTF 完成了锚定。 多模终端将语音会话切换到 WLAN网络后， 与视频会话会并， 再 切换合并的会话到第二接入网络（3G PS网络）。 本实施例中， 第三接入网络以 WLAN为例， 也可是其它 IP-CAN, 如 WiMAX等； 可以应用本发明实施例的 single radio切换还包括 2G CS 切换到 3G PS、LTE切换到 3G CS或者 2G CS等； 本实施例中媒体成分不限于语音呼叫， 也可以是其它或多种媒体成分。 参见图 7 所示， 包括下列步骤：
1 , 多模终端检测到即将发起切换， 确定的最终切换目的网络（3G PS网络） 与语音会话当前所在的 2G CS网络为单无线关系， 将中断用户的语音业务。
此时多模终端检测到当前可以接入到支持语音会话的 WLAN网络或 IPCAN 网络。多模终端根据切换策略选择与 2G CS网络存在双无线关系的 WLAN网络 作为中转切换该语音呼叫的第三接入网络。
2, 多模终端在 WLAN 中已有的视频会话中发起切换请求， 将语音会话切 换到 WLAN网络中， 并将视频会话和语音会话合并为多媒体会话。
3 , 多模终端检测到上述切换完成后 （如媒体已经转移到了 WLAN 中且多 模终端和 2G CS网络的所有连接已经释放）， 根据切换策略继续切换。
4, 多模终端在 3G PS网络中发起多媒体成分的切换， 将多媒体会话切换到 3G PS网络。
[实施例 5] 多模终端已经和远端 UE在第一接入网络（3G PS ) 中进行了语 音会话， 在第三接入网络（WLAN网络） 中进行了视频会话， 并都在 DTF完成 了锚定。 多模终端将语音会话切换到 WLAN网络后， 与视频会话会并。 呼叫经 第三接入网络既有会话中转后，将视频成分切换到第二接入网络（2G PS网络）。 本实施例中 , 第三接入网络以 WLAN接入为例 , 也可是其它 IP-CAN接入， 如 WiMAX等；可以应用本发明实施例的 single radio切换还包括 2G CS 切换到 3G PS、 LTE切换到 3G CS或者 2G CS等； 本实施例中媒体成分不限于语音呼叫， 也可以是其它或多种媒体成分。 参见图 8所示， 包括下列步骤：
1 , 多模终端检测到即将发起切换， 确定的最终切换目的网络（2G PS网络） 与语音会话当前所在的 3G PS网络为单无线关系， 将中断用户的语音业务。
此时多模终端检测到当前可以接入到支持语音呼叫的 WLAN网络或 IPC AN 网络。 多模终端根据切换策略选择与 3G PS网络存在双无线关系的 WLAN网络 作为中转切换该语音呼叫的第三接入网络。
2, 多模终端在 WLAN 网络中的既有视频会话中发起切换， 请求将第一接 入网络的语音成分合入。
3 , 多模终端检测到上述切换完成后 （如媒体已经转移到了 WLAN 中且多 模终端和 3G PS网络的所有连接已经释放）， 根据切换策略继续切换。
4, 多模终端在 2G PS网络中发起携带视频成分的切换请求， DTF收到后将 视频成分切换到 2G PS网络。 [实施例 6] 运营者设置或更新切换策略的流程（本实施例中仅以设备管理机 制为例并不限定于此机制， 其它切换策略， 如优选同一运营者网络进行切换的 策略也可以使用该方案来设置或更新）。 参见图 9所示， 包括下列步骤：
1 , 网络中的切换管理实体通过设备管理（DM )将切换策略信息 （此处以 中转切换的切换策略为例）发布到多模终端中。
2, 多模终端判定是第一次收到该切换策略， 则保存； 否则更新对应的切换 策略。
多模终端也可以向用户提供设置和更新切换策略的接口。
综上所述， 本发明实施例提供的实现呼叫连续性的方法， 由于多模终端在 第一接入网络中进行呼叫的过程中， 检测到将发生切换时， 不是任意选择目的 切换网络， 而是根据切换策略， 从与第一接入网络存在双无线关系的接入网络 中， 择一当前可用的第三接入网络， 并将第一接入网络中的呼叫切换到第三接 入网络。 所以在多模终端进行呼叫切换时， 保证了呼叫的连续性。
本发明实施例还提供了一种多模终端， 包括： 检测单元、 切换策略保存单 元、 选择单元和切换单元， 与本发明实施例提供的实现呼叫连续性的方法相对 应。
进一步， 由于本发明实施例提出了通过第三接入网络中转切换的方案， 所 以可避免 single radio环境给切换过程带来的呼叫中断，改善了用户的业务体验。 具体的， 由于通过与第一接入网络和第二接入网络均为双无线关系的第三接入 网络的中转， 避免了切换时 CS多媒体呼叫降质过程给用户带来的呼叫中断。
进一步， 本发明实施例中， 可由网络运营者或者用户设置或更新多模终端 中保存的切换策略。 当多模终端检测到有多个候选接入网络可供切换时， 可根 据切换策略， 选择与当前呼叫所在网络属于同一运营商的接入网络进行切换， 从而提高该运营商的网络使用率， 提高运营者的收益。 明的精神和范围。 这样， 倘若本发明的这些修改和变型属于本发明权利要求及 其等同技术的范围之内， 则本发明也意图包含这些改动和变型在内。

Claims

权 利 要 求
1、 一种实现呼叫连续性的方法， 其特征在于， 包括下列步骤：
多模终端在第一接入网络中进行呼叫时， 检测到将发生切换；
多模终端根据切换策略， 从与第一接入网络存在双无线关系的接入网络中， 择一当前可用的第三接入网络； 以及
多模终端将第一接入网络中的呼叫切换到第三接入网络。
2、 如权利要求 1所述的方法， 其特征在于， 所述多模终端至少检测到下述 情况之一， 则判定为检测到将发生切换：
检测到呼叫在第一接入网中即将失去连接；
检测到呼叫当前的服务质量低于预先设置的门限值；
检测到用户的切换操作指示；
检测到存在通信资费低于第一接入网络的接入网络。
3、 如权利要求 1所述的方法， 其特征在于， 切换策略要求将所述呼叫切换 到与第一接入网络存在单无线关系的第二接入网络时， 多模终端从与第一接入 网络和第二接入网络均存在双无线关系的接入网络中， 择一当前可用的第三接 人网； 以及
将第一接入网络中的呼叫切换到第三接入网络后， 再将该呼叫从第三接入 网络中转切换到第二接入网络。
4、 如权利要求 3所述的方法， 其特征在于， 多模终端通过下述方式检测所 述呼叫已切换到第三接入网络： 呼叫的媒体通道已经转移到第三接入网络， 并 且该多模终端与第一接入网络的连接已经释放。
5、 如权利要求 3所述的方法， 其特征在于， 多模终端在第三接入网中发起 切换请求， 或者在第三接入网中的既有会话中发起切换请求， 以将呼叫从第一 接入网切换到第三接入网。
6、 如权利要求 1所述的方法， 其特征在于， 所述切换策略优选与第一接入 网络归属于同一运营商的第三接入网络。
7、 如权利要求 1、 3或 6 所述的方法， 其特征在于， 由网络运营者或者用 户设置或更新保存在所述多模终端中的切换策略。
8、 一种多模终端， 其特征在于， 包括：
检测单元， 用于在该多模终端在第一接入网络中进行呼叫时， 检测是否将 发生切换， 并在将发生切换时， 发出触发信号；
切换策略保存单元， 用于保存切换策略；
选择单元， 用于以收到检测单元发出的触发信号作为触发条件， 根据切换 策略保存单元保存的切换策略， 从与第一接入网络存在双无线关系的接入网络 中， 择一当前可用的第三接入网络；
切换单元， 用于将第一接入网络中的呼叫切换到第三接入网络。
9、 如权利要求 8所述的多模终端， 其特征在于， 所述检测单元至少检测到 下述情况之一， 则判定为检测到将发生切换：
检测到呼叫在第一接入网中即将失去连接；
检测到呼叫当前的服务质量低于预先设置的门限值；
检测到用户的切换操作指示；
检测到存在通信资费低于第一接入网络的接入网络。
10、 如权利要求 8 所述的多模终端， 其特征在于， 切换策略保存单元保存 的切换策略要求将所述呼叫切换到与第一接入网络存在单无线关系的第二接入 网络， 则
选择单元从与第一接入网络和第二接入网络均存在双无线关系的接入网络 中， 择一当前可用的第三接入网；
切换单元将所述呼叫切换到第三接入网络后， 再将该呼叫从第三接入网络 中转切换到第二接入网络。
11、 如权利要求 8或 10所述的多模终端， 其特征在于， 切换策略保存单元 中保存的切换策略， 由网络运营者或者用户设置或更新。
PCT/CN2008/071799 2007-07-30 2008-07-29 Procédé assurant la continuité des appels et dispositif correspondant WO2009015601A1 (fr)

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