CN1319409C - Switching method for keeping continuous communication in mobile communication system - Google Patents

Abstract

The invention relates to a switching method of a mobile communication system, and discloses a switching method for maintaining continuous communication in the mobile communication system, so that the communication is not interrupted when the switching occurs, and the continuity of sound playback and data services is maintained. In the present invention, the new terminal in the context after switching is notified to inherit the channel of the original terminal through the extended switching packet, so that the new terminal continues to communicate through the same channel, thereby maintaining the continuity of communication. For the synchronous tone channel in the playback process For the IWF instance channel in the data service communication, different takeover channel signals are defined in the switching packet to carry related parameters; the channel inheritance and continuous communication can also be realized through the change of the network topology between terminals in the context.

Description

Handover method for maintaining continuous communication in mobile communication system

technical field

The invention relates to a switching method of a mobile communication system, in particular to a switching method for maintaining continuous communication in the mobile communication system.

Background technique

With the rapid development of communication technology, people's expectations and requirements for personal communication are getting higher and higher, so mobile operators need to pay special attention to aspects such as user interface and service quality that directly affect the effect of users using mobile services. The characteristics of the third generation (3rd Generation, referred to as "3G") mobile communication system, such as high bandwidth, multiple services, and high quality, have greatly attracted the mobile consumer market. To a certain extent, it restricts market expansion and affects the development of mobile operation affairs.

Wideband Code Division Multiple Access (WCDMA for short) mobile communication system consists of a core network (Core Net, referred to as "CN"), a Universal Mobile Telecommunications System Terrestrial Radio Access Network (UMTS Terrestrial Radio Access Network, referred to as "UTRAN") and user equipment (User Equipment, referred to as "UE"). UTRAN and UE adopt WCDMA radio access technology. The WCDMA network follows the following principles when designing: The functions of the wireless access network and the core network should be separated as far as possible. That is, the management function of radio resources is concentrated in the radio access network, while the functions related to services and applications are executed in the core network.

The basic feature of the WCDMA network architecture is that the core network gradually evolves and transitions from the core network of the Global System for mobile Communication ("GSM"). The wireless access network is a revolutionary change, it will be completely different from the GSM wireless access network; and in terms of business, it is fully compatible with GSM business, which fully reflects the continuity of business

In the network architecture after R4 of WCDMA, the core network is no longer limited to circuit switching, but can choose packet switching, such as Asynchronous Transfer Mode (Asynchronous Transfer Mode, referred to as "ATM"), Internet Protocol (Internet Protocol, referred to as "IP") as the bearer technology. Packet switching not only improves the network transmission rate and enriches the types of network services, but also facilitates network management and network structure design. At the same time, in order to realize the separation of call control and bearer control, the mobile switching center (Mobile Switching Center, referred to as "MSC") is divided into MSC server (G MSC Server) and media gateway (Media Gateway, referred to as "MGW"), where (G ) The MSC Server completes the call control and mobility management functions, and the MGW completes the bearer control and transmission functions. The interface between the two is called the Mc interface, and H.248 is used as the bearer control protocol. The core network and the access network communicate through the radio network controller (Radio Network Controller, referred to as "RNC") and the Iu interface of the MSC. The control channel is between the RNC and the MSC Server, and the RNC accepts the signaling control of the MSC Server. There is a data channel between the RNC and the MGW, and the data of the RNC is aggregated and distributed through the MGW. On the wireless access side, when the UE accesses wirelessly through a cell base station node (NodeB), it is controlled by the RNC.

The core network also completes the function of integrating with other networks, in which the MSC Server maintains the signaling interaction interface between the mobile network and other networks, and the MGW implements functions such as data forwarding and channel establishment. Figure 1 shows a call networking model in which a mobile user calls a fixed user. MSC Server completes the link control and maintenance from RNC to Public Service Telecommunications Network (Public Service Telecommunication Network, referred to as "PSTN"), while MGW has a context (Context) to establish a connection between RNC and PSTN. Terminal (Termination) T1 Receive RNC signals, T2 receives PSTN signals, realize signal modulation matching in the context, etc. The call connection process from a mobile user UE to a PSTN fixed user is described as follows:

First, after the mobile UE completes the wireless access, it sends a message through the air interface to initiate a call (Setup), and the message carries the called number;

Secondly, this signaling is delivered to MSC Server by RNC, and MSC Server analyzes called number, it is characterized in that, described step B1 also comprises following substep:

When the system plays the sound to the user, it establishes a virtual terminal in the context, the virtual terminal accepts the sound signal, and sets a one-way topology from the virtual terminal to the original terminal, and the virtual terminal passes through the The original terminal plays the sound to the user;

When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the virtual terminal to the new terminal, and the virtual terminal simultaneously playing sound through the original terminal and the new terminal;

After the handover is completed, the resources of the original terminal are released.

11. The handover method for maintaining continuous communication in the mobile communication system according to claim 9, characterized in that, said step B1 also includes the following sub-steps:

During the data service communication process, a two-way topology between the original terminal and the terminal on the other side of the channel is set in the context for communication;

When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the terminal on the other side of the channel to the new terminal, while maintaining the Describe the bidirectional topology between the original terminal and the terminal on the other side of the channel;

After the media gateway detects the change of the network topology, it transfers the channel of the interactive function instance from the original terminal to the new terminal, and sets the connection between the terminal on the other side of the channel and the original terminal. a one-way topology, setting a two-way topology between the new terminal and the terminal on the other side of the channel;

After the handover is completed, the resources of the original terminal are released.

12. The handover method for maintaining continuous communication in the mobile communication system according to any one of claims 1 to 3, characterized in that the method further comprises the following steps:

The mobile switching center server judges whether an event request has been sent to the original terminal, and if so, re-sends the event request to the new terminal;

When the PSTN side sends an off-hook message (ANM), the MSC Server sends a modification (MODIFY) command (H.248 message) to the MGW, instructing to activate the IWF. According to 3GPP TS 29.232 V.4.8.0, the MGW is in T1/T2 Send the signal to activate the higher layer protocol (Activate the higher layer protocol, referred to as "actprot"), and request to detect the protocol negotiation result (Protocol Negotiation Result, referred to as "protres") event. At this time, on the mobile side, that is, on the connection with T1, the IWF will perform the synchronization of the Radio Link Protocol (Radio Link Protocol, "RLP") and the point-to-point protocol (Point-to-Point Protocol, "PPP") negotiation. On the fixed side, ie the connection to T2, the IWF performs the usual modem negotiations. The MGW reports a protres event to the MSC Server, indicating the negotiation result. After the negotiation is completed, data can be sent and received between the mobile station and the fixed user.

In the mobile access network, when the UE moves to access the NodeB in the cell coverage area, there is a handover problem between different cells, that is, when the UE enters another cell from one cell, or due to reasons such as radio signal quality or network load When a user is handed over, the NodeB communicating with it also changes, and even the RNC also changes. During the handover process of the base station, the RNC side of the communication link needs to be reset. This brings discontinuity to ongoing communications, such as the system's ongoing announcement or user data traffic.

If the local office needs to perform an announcement operation for the user, for example, the called number is wrong and the connection fails, the MSC Server will send an announcement instruction to the terminal in the MGW. The playback content can be divided into two types. One is that there is no clear start mark, and the user can start listening to the sound from any position, such as the busy tone of "beep...beep...beep...", which is called asynchronous tone ; The other one has a clear start mark, and the user needs to listen to the tone from the beginning, such as the pre-recorded voice "The number you dialed does not exist, please check and dial again", which is called synchronous tone. According to the H.248 specification, playback is realized by sending a signal (Signal) up and down the terminal. This is no problem under normal circumstances, but when the user switches, it may cause playback interruption.

As the first step in the handover process, according to 3GPP TS 23.205 V4.7.0, when the UE is handed over, the MSC Server will receive a handover request from the RNC side, and a new terminal should be added (ADD) in the context of the MGW , such as named T1 ', which is connected to the new ground circuit. When the UE switches to the new air channel, the new NodeB/RNC will detect the user's access, and after the MSC Server gets the report, it will notify the original RNC to release the call-related resources and delete the original terminal T1 on the context of the MGW. And if during the handover process, the MGW is playing the user's announcement, that is, there is a signal on T1, then after the user switches to the new air channel, it is connected through the ground circuit corresponding to T1', so the announcement on T1 If it cannot be transmitted to the user, playback to the user will suddenly stop.

Similarly, when a mobile user performs data communication, such as connecting to a fixed network through an IWF, if the mobile user is handed over, as mentioned above, after receiving the handover request, the MSC Server should add (ADD) a A new terminal, T1', is connected to the new ground circuit. The same BC parameters as T1 are delivered on this T1′, but because the original IWF works based on the negotiation result with the original mobile terminal and the fixed terminal, the IWF is connected to T1 before the handover, and will be connected to T1′ after the handover connected. If the new terminal does not directly inherit the IWF for communication, the IWF will need to conduct a new negotiation, obtain the negotiation result between the new terminal and the fixed side, and continue the communication. This process will inevitably lead to interruption and discontinuity of communication services.

For the interruption of playback caused by switching, one solution is that after the switching is completed, the MSC Server also sends the same signal on the new terminal T1', so that the system continues to play the sound to the user. For asynchronous tones, since there is no clear start mark, no matter when the user starts to listen, it has no effect; for synchronous tones, this will cause discontinuous playback, such as playing "The number you dialed does not exist, please check "Dial again" prompt, when the word "no" is placed, a switch occurs, the user switches from listening to the playback from T1 to listening to the playback from T1', and T' restarts the playback, so the actual voice heard is It may be "the number you dialed does not exist, please check and dial again", the discontinuous synchronous tone causes inconvenience or even misunderstanding for users to understand.

When the user switches during playback, if the MSC Server does not send the same signal to the new terminal after the switch, it will cause the user to listen to the audio and it will suddenly stop; if the MSC Server sends the same signal to the new terminal after the switch, the user The voice heard is a combination of discontinuous fragments, resulting in discontinuous playback, and the voice effect is extremely unsatisfactory, especially when playing synchronous sounds.

As for the communication service of the mobile user, especially when inter-network communication is performed through the IWF, the data service is interrupted due to the renegotiation of the IWF. If no measures are taken to make the new terminal after switching inherit the original IWF, the data service will be interrupted until the new IWF completes the negotiation between the mobile side and the fixed network side again.

In practical application, the above solution has the following problems: discontinuous communication due to user switching, user interface deterioration due to audio playback interruption, or data service interruption resulting in reduced transmission efficiency and service quality.

The main reason for this situation is that when the handover occurs, the new terminal does not inherit the channel of the original terminal, but re-uses or negotiates a new channel for communication.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a handover method for maintaining continuous communication in a mobile communication system, so that the communication is not interrupted when the handover occurs, and the continuity of the announcement and data services is maintained.

To achieve the above object, the present invention provides a handover method for maintaining continuous communication in a mobile communication system, comprising the following steps:

A When handover occurs, the mobile switching center server issues a command to establish a new terminal in the context of the media gateway;

The new terminal described by B inherits the channel of the original terminal and uses this channel to continue communication.

Wherein, the channel is a synchronous sound channel, which is used for the system to play sound to the user.

The channel is an interactive function instance channel for data service communication.

Said step B also includes the following sub-steps,

The mobile switching center server sends a switching packet to the media gateway;

The media gateway transfers the channel from the original terminal to the new terminal according to the information carried in the switching packet;

Wherein the switching packet is used to carry a signal to take over the channel.

The switching packet includes a takeover synchronous tone channel signal, the takeover synchronous tone channel signal is used to instruct the new terminal to take over the synchronous tone channel of the original terminal, and the takeover synchronous tone channel signal includes an initial terminal identification parameter, Used to specify the original terminal in the context.

The processing flow of the switching packet includes the following steps,

During the system playing the sound to the user, the mobile switching center server establishes the new terminal in the media gateway after receiving the switching request, and sends the switching packet to the new terminal in the media gateway , the switching packet includes a signal that is the takeover synchronous tone channel signal;

The media gateway judges whether the terminal specified by the initial terminal identification parameter carried by the takeover synchronous tone channel signal has the synchronous tone channel and is in the same context as the new terminal, and if so, sets the The synchronous tone channel is transferred to the new terminal, otherwise, an error is returned to the mobile switching center server.

The switching packet includes a takeover interaction function instance signal, the takeover interaction function instance signal is used to instruct the new terminal to take over the interaction function instance channel of the original terminal, and the takeover interaction function instance signal includes the initial terminal An identification parameter used to specify the original terminal in the context.

The processing flow of the switching packet includes the following steps,

During the data service communication process, after receiving the switching request, the mobile switching center server establishes the new terminal at the media gateway, and sends the switching packet to the new terminal, and the switching packet includes a signal of Said taking over the interaction function instance signal;

The media gateway judges whether the terminal specified by the initial terminal identification parameter carried by the takeover interaction function instance signal has the interaction function instance channel and is in the same context as the new terminal, and if so, then Transfer the interactive function instance channel to the new terminal, otherwise, return an error to the MSC server.

Said step B also includes the following sub-steps,

B1 When the handover occurs, transfer the channel from the original terminal to the new terminal through the change of the topology between the terminals in the context.

The step B1 also includes the following sub-steps:

When the system plays the sound to the user, it establishes a virtual terminal in the context, the virtual terminal accepts the sound signal, and sets a one-way topology from the virtual terminal to the original terminal, and the virtual terminal passes through the The original terminal plays the sound to the user;

When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the virtual terminal to the new terminal, and the virtual terminal simultaneously playing sound through the original terminal and the new terminal;

After the handover is completed, the resources of the original terminal are released.

The step B1 also includes the following sub-steps:

During the data service communication process, a two-way topology between the original terminal and the terminal on the other side of the channel is set in the context for communication;

When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the terminal on the other side of the channel to the new terminal, while maintaining the Describe the bidirectional topology between the original terminal and the terminal on the other side of the channel;

After the media gateway detects the change of the network topology, it transfers the channel of the interactive function instance from the original terminal to the new terminal, and sets the connection between the terminal on the other side of the channel and the original terminal. a one-way topology, setting a two-way topology between the new terminal and the terminal on the other side of the channel;

After the handover is completed, the resources of the original terminal are released.

The method also includes the steps of:

The mobile switching center server judges whether an event request has been sent to the original terminal, and if so, re-sends the event request to the new terminal;

After the handover is completed, the resources of the original terminal are released.

Through comparison, it can be found that the main difference between the technical solution of the present invention and the prior art is that the present invention notifies the new terminal in the context after switching through the extended switching packet to inherit the channel of the original terminal, so that the new terminal continues to communicate through the same channel, In order to maintain the continuity of communication, for the synchronous audio channel in the playback process and the IWF instance channel in the data service communication, different takeover channel signals are defined in the switching packet to carry relevant parameters; or through the context between terminals Changes in the topology of the network to achieve channel inheritance and continuous communication. For the playback process, a virtual terminal is added to play the sound to the new terminal and the original terminal at the same time when switching to achieve the continuity of the synchronous tone. For data services The communication detects the occurrence of handover through the change of topology between terminals in the context, so as to transfer the IWF instance channel from the original terminal to the new terminal, thereby ensuring the continuity of data services.

The difference in this technical solution has brought obvious beneficial effects, that is, the continuity of synchronous playback and data service communication is realized through extended switching packets or network topology changes, and the interruption of synchronous playback caused by switching is solved. , data service interruption and other issues, improving the friendliness of the user interface is conducive to expanding the business market. The problem caused by switching is solved, the transmission efficiency is improved, and the service quality is improved.

Description of drawings

Fig. 1 is a schematic diagram of a calling network in which a mobile user calls a fixed user;

2 is a flowchart of a handover method for maintaining continuous communication by handover packets according to an embodiment of the present invention;

Fig. 3 is a schematic diagram of changes in terminal connections in the context during the process of taking over the synchronous tone channel according to an embodiment of the present invention;

Fig. 4 is a schematic diagram of changes in the connection between the terminal and the IWF instance in the context during the process of taking over the IWF instance channel according to an embodiment of the present invention;

5 is a schematic diagram of a network topology change process for realizing continuous playback according to an embodiment of the present invention;

Fig. 6 is a schematic diagram of a network topology change process for implementing continuous data services according to an embodiment of the present invention.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings.

The present invention maintains continuous communication through the method that the new terminal inherits the channel of the original terminal. Under the framework of the H.248 protocol, through the custom extension package (switching package), it is used for MSC Server to notify and send parameters to the new terminal, so that it can inherit the channel of the original terminal and transfer the synchronous tone channel when the system plays sound , transfer the IWF instance channel during the data service communication, so that the new terminal can continue to communicate on the original channel, thereby maintaining the continuity of the announcement or data service. In the extended switching package, it is necessary to define the necessary parameters for inheriting the synchronous audio channel or the IWF instance channel, and at the same time, all functional entities of the core network jointly implement the necessary process for channel inheritance. In addition, the present invention also provides a switching method for channel inheritance and continuous communication through changes in the network topology in the context of the MGW. When the system plays sound, by adding a virtual terminal, the topological structure among the three terminals Changes occur during switching, so that the new terminal inherits the synchronous audio channel of the original terminal. During data service communication, there is a network topology structure in the connection of the IWF instance. Therefore, the IWF is realized by detecting the occurrence of switching and related information of the topology change. The inheritance of the instance channel finally realizes the purpose of continuous communication when switching.

In one embodiment of the present invention, the channel inheritance under the control of the MSC Server, such as the inheritance of the synchronous tone channel or the IWF instance channel, is realized through the extended switching package. When the MSC Server receives the handover request from the RNC side, it immediately sends it to the MGW and establishes a new terminal (Termination, referred to as "T") in the context. The new T establishes a connection with the ground circuit, which is used to Access communication to the new RNC. At the same time, MSC Server needs to issue a switching packet, which carries the parameters required for switching. After the new T receives the switching packet, it can inherit the channel of the original T according to the parameters to keep the communication going on continuously.

In one embodiment of the present invention, the format of the handover package (Handover Package) is defined as follows: the package ID (PackageID) is threegho, and its hexadecimal value is determined by the Internet Assigned Numbers Authority (Internet Assigned Numbers Authority, referred to as "IANA") ) allocation, where threegho is the abbreviation of 3GHandOver. Other parameters are defined as follows, such as Version: 1, Extends: None, Properties: None, Events: None, Signals: Take over various channel-related signals, statistics ( Statistics): None. Among them, the switching package is used to define the signals needed to ensure smooth switching during switching, which is one of the key parameters. This signal carries the parameters necessary for the new T to take over the channel of the original T.

In one embodiment of the present invention, the signal of the switching packet defines a signal for taking over the synchronous tone channel: Take over the synchronous tone channel (Take over announcement channel). The parameters carried by the signal that takes over the synchronous audio channel include:

Signal ID (SignalID): tkann (O×0001), which is an English abbreviation, is used to identify the signal; Signal Description (Description): captures the synchronous tone channel on the specified terminal, and is used to notify the new T to take corresponding actions; signal Type (Signal type): Brief; Duration (Duration): None. The additional parameters included are as follows: Original Termination ID: the original T ID, which is one of the key parameters for the new T to obtain the positioning operation object; Parameter ID: oriterm (O×0001), used to specify the nature of additional parameters; Type (Type): integer, specifying the data type of additional parameters, considering the naming convention of 3GPPTS 29.232 V.4.8.0 for terminal identification, when binary encoding is used, the terminal The identifier is 4 bytes, so it is sufficient to use an integer; Possible values: any legal terminal identification number, but does not include root (Root) and wildcards; Parameter description (Description): Indicates which terminal to take over A terminal sync tone channel.

It can be seen that the above-mentioned signal taking over the synchronous tone channel defines the parameters required for the new T to take over the synchronous tone channel of the original T, such as the identification number of the original T, action description and so on. This signal is used during system playback. If a handover occurs, the MSC Server will send a signaling to establish a new T after receiving the handover request from the RNC side, and send a handover with this signal to the MGW After receiving the switching packet, the MGW learns the command to take over the synchronous tone channel according to the signal description, and the MGW transfers the synchronous tone channel that is playing on the original T to the new T according to the identification number of the original T. After the new RNC establishes a connection with the new T, so as to continue the task of playing sound, realize the function of continuous sound playing when switching, and solve the problem of sound interruption or discontinuity.

In one embodiment of the present invention, the signal of the switching package defines a signal for taking over the IWF instance channel: Take over IWF instance (Take over interworking function). The parameters carried by the signal that takes over the IWF instance include:

Signal ID (SignalID): tkiwf (0×0002), which is an English abbreviation, is used to identify the signal; Signal Description (Description): captures the IWF instance on the specified terminal, and is used to notify the new T to take corresponding actions; signal type (Signal type): Brief; Duration: None. The additional parameters included are as follows: Original Termination ID: the original T ID, which is one of the key parameters for the new T to obtain the positioning operation object; Parameter ID: oriterm (O×0001), used to specify the nature of additional parameters; type (Type): integer, specifying the data type of additional parameters; range of values (Possible values): any legal terminal identification number, but does not include the root (Root ) and wildcards; parameter description (Description): indicates which IWF instance of the terminal to take over.

It can be seen that the above signal to take over the IWF instance channel defines the parameters required for the new T to take over the IWF instance channel of the original T, such as the identification number of the original T, action description, and so on. This signal is used for data service communication. For example, during the communication between a mobile user and a fixed user, if handover occurs, the MSC Server will issue a signaling to establish a new T after receiving the handover request from the RNC side, and send The MGW sends a switching packet with this signal. After receiving the switching packet, it knows the command to take over the IWF instance channel according to the signal description. The MGW transfers the IWF on the original T that is communicating with the data service according to the identification number of the original T. The instance channel is inherited by the new T. After the user accesses the new RNC, a connection is established with the new T, so as to continue the data service in communication, realize the function of continuous communication during handover, and solve the problem of data service interruption or discontinuity.

In another embodiment of the present invention, text encoding is used for the parameter "initial terminal identifier" in the switching packet signal. According to H.248, the terminal identifier can be as long as 64 characters, so the data type is defined as a character string.

Those skilled in the art can understand that the specific format and parameter definition and value of the above switching packet can be set according to the actual situation so as to conveniently and reasonably realize the carrying of the parameters required by the inheritance channel. The format of the signal and the carrying parameters It can be expanded according to the needs in practical applications to realize switching and inheritance of more types of channels, not limited to the solutions given in the embodiments, and achieve the purpose of the invention without affecting the essence and scope of the present invention.

In one embodiment of the present invention, procedures (Procedures) implemented by network entities such as MSC, MGW, terminal, etc. corresponding to various signals in the above handover packet are defined accordingly.

When the MGW receives the "take over synchronous tone channel" signal, it should check the "initial terminal identification" parameter carried in the signal, if there is a synchronous tone channel on the specified terminal, and the terminal is in the same context as the terminal that received the signal , then it should be seized and handed over to the terminal that received the "take over synchronization tone channel" signal. If there is no synchronous tone channel on the specified terminal, or not in the same context, an error should be returned to MSC Server.

When the MGW receives the "Take over IWF instance" signal, it should check the "initial terminal identification" parameter carried in the signal. If there is an IWF instance on the specified terminal, and the terminal is in the same context as the terminal that received the signal, then It should be captured and handed over to the terminal that received the "take over IWF instance" signal. If there is no IWF instance on the specified terminal, or not in the same context, an error should be returned to MGC Server.

According to the definition of the aforementioned handover packet, FIG. 2 shows the flow of a handover method for maintaining continuous communication according to an embodiment of the present invention.

At first in step 201, after MSC Server receives handover request, issue and join (ADD) instruction and set up a new T in the context, new T is connected with new ground circuit, after the user switches to the new air channel, The new NodeB/RNC detects the user's access and reports it to the MSC Server.

Then enter step 202, the MSC Server sends a handover packet with a signal to take over the corresponding channel on the new T, and notifies the MGW to transfer the channel on the original T to the new T, and the MGW according to the parameters carried by the signal in the handover packet, such as The initial terminal identifier, and the new T takes over and inherits the channel of the original T.

Then enter step 203, the MSC Server re-sends the event requests originally sent to the original T on the new T, such as the notification of the end of the announcement, the notification of the change of the service rate, etc., to ensure the integrity of the signaling communication and avoid resource loss .

Then enter step 204, after the handover is completed, the new T continues to communicate on the original T channel, and the MSC Server notifies the original RNC to release the call-related resources, and deletes the original T on the MGW.

According to the above process, in one embodiment of the present invention, the switching process corresponding to the synchronous sound channel takeover is described as follows: when the system plays the sound to the user through T1, the switching occurs, and after receiving the switching request, the MSC Server in the context Create a new T, named T1′, which is connected to the new ground circuit; after the user switches to the new air channel, the new NodeB/RNC will detect the user’s access, and after the MSC gets the report, if the user is on the original T1 If the synchronous tone is being played, the signal threegho/tkann is sent up and down T1' (that is, the signal is a switching packet to take over the synchronous tone channel), requesting the MGW to transfer the synchronous tone channel on T1 to T1'; after completing the inheritance of the synchronous tone, The new T can continue to play the sound to the user; if the MSC Server has sent an event request to T1, such as the announcement of the end of the sound, then the MSC Server should send the event request again at the same time as T1's signal threegho/tkann ; After the handover is completed, notify the original RNC to release call-related resources, and delete T1 on the MGW. Fig. 3 shows the change of the terminal connection in the context during the process of taking over the synchronous tone channel according to an embodiment of the present invention.

According to the above process, in one embodiment of the present invention, the switching process corresponding to the channel takeover of the IWF instance is described as follows: when the user is communicating with the data service, in a context of the MGW, the terminal T1 is connected to the terminal T2 through the IWF instance, When the user is handed over, after receiving the handover request, MSC Server creates a terminal in the context, named T1′, which is connected to the new ground circuit; after the user switches to the new air channel, the new NodeB/RNC will After detecting the user's access and the MSC getting the report, if there is an IWF instance on the original T1, it will send a signal threegho/tkiwf up and down T1' (that is, the signal is a switching packet to take over the channel of the IWF instance), requiring the MGW to transfer the IWF instance on T1 The IWF instance is transferred to T1′; after the channel inheritance of the IWF instance is completed, the new T maintains the continuous data service communication; if the MSC Server has sent an event request to T1, such as a rate change notification, the MSC Server should send the event request to T1′ While signaling threegho/tkiwf, re-send the event request; after the handover is completed, notify the original RNC to release call-related resources and delete T1 on the MGW. Fig. 4 shows the changes of the terminal and IWF instance connections in the context during the process of taking over the IWF instance channel according to an embodiment of the present invention.

In one embodiment of the present invention, the transfer of the channel of the original T to the new T is realized by changing the topology structure of the terminal network in the context during the handover.

Fig. 5 shows the network topology change process for realizing continuous playback according to an embodiment of the present invention. For the situation where the system performs synchronous playback for users, there is no network topology between multiple Ts in the context. Structure, so virtual T is added to form a network topology. The system releases the synchronous tone to the virtual T, and then the virtual T plays the tone to the original T or the new T. That is, when the system needs to play the synchronous tone to the original T (called T1), it does not directly send the tone signal up and down T1, but It is to establish another virtual T (called T2), and specify the topology as T2->T1 unidirectional, and the announcement signal is sent to T2, and the system plays the announcement to the user through the topology structure from T2 to T1. The user is actually listening to the T2 playback. When T1 is switched, a new T (called T1') needs to be established to correspond to the new ground circuit. At this time, the designated topology is T2->T1' one-way. During this switching process, T2 plays sound to T1 and T1' at the same time , so whether the user accesses from T1 or T1' before and after switching, the listening effect will not be affected, and continuous playback will be maintained. After the switching is over, T1 can be deleted, and after listening to the audio, T2 can be deleted, so as to ensure that resources are not wasted.

Fig. 6 shows the network topology change process of realizing continuous data service according to one embodiment of the present invention. For the situation of data service communication, since in the context T1 (original T) on the mobile side and T2 on the other side have passed through the IWF instance The connection is established, and there is a network topology relationship between the two. When T1 switches, a new T (called T1′) needs to be established to correspond to the new ground circuit. At this time, the specified topology is T2<->T1 bidirectional, T2- > T1' one-way; when it is detected that the user has switched to a new air channel, the topology is modified to T2->T1 one-way, T2->T1' two-way, and the MGW judges that a switch has occurred based on the change of the topology, and sets the IWF The instance channel is transferred from T1 to T1', so T1' inherits the original IWF instance channel of T after switching, and continues to communicate with data services.

Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein, and without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (12)

1. A handover method for maintaining continuous communication in a mobile communication system, characterized in that, comprising the following steps: A When handover occurs, the mobile switching center server issues a command to establish a new terminal in the context of the media gateway; The new terminal described by B inherits the channel of the original terminal and uses this channel to continue communication. 2. The switching method for maintaining continuous communication in the mobile communication system according to claim 1, wherein the channel is a synchronous tone channel for the system to play a tone to the user. 3. The switching method for maintaining continuous communication in the mobile communication system according to claim 1, wherein the channel is an interactive function instance channel for data service communication. 4. The handover method for maintaining continuous communication in the mobile communication system according to any one of claims 1 to 3, characterized in that, said step B also includes the following sub-steps, The mobile switching center server sends a switching packet to the media gateway; The media gateway transfers the channel from the original terminal to the new terminal according to the information carried in the switching packet; Wherein the switching packet is used to carry a signal to take over the channel. 5. The handover method for maintaining continuous communication in the mobile communication system according to claim 4, wherein the handover packet includes a takeover synchronous tone channel signal, and the takeover synchronous tone channel signal is used to instruct the new terminal to take over For the synchronous tone channel of the original terminal, the takeover synchronous tone channel signal includes an initial terminal identification parameter, which is used to specify the original terminal in the context. 6. The handover method for maintaining continuous communication in the mobile communication system according to claim 5, characterized in that, the processing flow of the handover packet comprises the following steps, During the system playing the sound to the user, the mobile switching center server establishes the new terminal in the media gateway after receiving the switching request, and sends the switching packet to the new terminal in the media gateway , the switching packet includes a signal that is the takeover synchronous tone channel signal; The media gateway judges whether the terminal specified by the initial terminal identification parameter carried by the takeover synchronous tone channel signal has the synchronous tone channel and is in the same context as the new terminal, and if so, sets the The synchronous tone channel is transferred to the new terminal, otherwise, an error is returned to the mobile switching center server. 7. The handover method for maintaining continuous communication in a mobile communication system according to claim 4, wherein the handover packet includes a takeover interaction function instance signal, and the takeover interaction function instance signal is used to instruct the new terminal to take over For the interactive function instance channel of the original terminal, the takeover interactive function instance signal includes the initial terminal identification parameter, which is used to specify the original terminal in the context. 8. The handover method for maintaining continuous communication in the mobile communication system according to claim 7, wherein the processing flow of the handover packet comprises the following steps, During the data service communication process, after receiving the switching request, the mobile switching center server establishes the new terminal at the media gateway, and sends the switching packet to the new terminal, and the switching packet includes a signal of Said taking over the interaction function instance signal; The media gateway judges whether the terminal specified by the initial terminal identification parameter carried by the takeover interaction function instance signal has the interaction function instance channel and is in the same context as the new terminal, and if so, then Transfer the interactive function instance channel to the new terminal, otherwise, return an error to the MSC server. 9. The handover method for maintaining continuous communication in the mobile communication system according to any one of claims 1 to 3, wherein said step B also includes the following sub-steps, B1 When the handover occurs, transfer the channel from the original terminal to the new terminal through the change of the topology between the terminals in the context. 10. The handover method for maintaining continuous communication in the mobile communication system according to claim 9, characterized in that, said step B1 also includes the following sub-steps: When the system plays the sound to the user, it establishes a virtual terminal in the context, the virtual terminal accepts the sound signal, and sets a one-way topology from the virtual terminal to the original terminal, and the virtual terminal passes through the The original terminal plays the sound to the user; When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the virtual terminal to the new terminal, and the virtual terminal simultaneously playing sound through the original terminal and the new terminal; After the handover is completed, the resources of the original terminal are released. 11. The handover method for maintaining continuous communication in the mobile communication system according to claim 9, characterized in that, said step B1 also includes the following sub-steps: During the data service communication process, a two-way topology between the original terminal and the terminal on the other side of the channel is set in the context for communication; When handover occurs, the mobile switching center server issues a command to establish the new terminal in the context, and set the unidirectional topology from the terminal on the other side of the channel to the new terminal, while maintaining the Describe the bidirectional topology between the original terminal and the terminal on the other side of the channel; After the media gateway detects the change of the network topology, it transfers the channel of the interactive function instance from the original terminal to the new terminal, and sets the connection between the terminal on the other side of the channel and the original terminal. a one-way topology, setting a two-way topology between the new terminal and the terminal on the other side of the channel; After the handover is completed, the resources of the original terminal are released. 12. The handover method for maintaining continuous communication in the mobile communication system according to any one of claims 1 to 3, characterized in that the method further comprises the following steps: The mobile switching center server judges whether an event request has been sent to the original terminal, and if so, re-sends the event request to the new terminal; After the handover is completed, the resources of the original terminal are released.