KR100353086B1 - Handoff Processing Method Using Gatekeeper - Google Patents

Abstract

The present invention enables a handoff to be handled even for a terminal that cannot conduct a multiparty conference by using a third party-directed pause and rerouting function by a gatekeeper managing a zone of an area in an H.323 network. The present invention relates to a handoff processing method using a gatekeeper. In the related art, a handoff is performed through multi-party conference signaling, which causes a complex signaling to a terminal, thereby increasing the load, and thus a long handoff time. The handoff signaling of the mobile terminal is not transparent as the signaling messages are exchanged in consideration of the mobile terminal before moving to another subnet that does not actually exist.

Accordingly, in the present invention, if a terminal can process an empty input / output set message in an H.323 network, the gatekeeper becomes a third party and handles the handoff by using a pause and rerouting function of the terminal led by the multiparty conference. A handoff of a terminal that does not support a mode can be handled, and at the same time, a simpler and faster handoff process can be performed than a handoff through a conventional multi-party conference mode.

Description

Handoff Processing Method Using Gatekeeper

The present invention relates to a handoff processing method using a gatekeeper. In particular, a multi-party conference can be performed by using a third party-driven pause and rerouting function by a gatekeeper managing a zone in a H.323 network. The present invention relates to a handoff processing method using a gatekeeper which enables handoff processing even for a terminal which cannot be used.

In general, IP Telephony, also known as Voice over Internet Protocol (VoIP), transmits data two-way in real time over the Internet or an intranet. These IP phones are called SONET / SDH (Synchronous). Optical communication technology in Optical NETwork / Synchronous Digital Hierarchy accelerates network interconnection, while x-DSL (x Digital Subscriber Line) technology solves the problem of latency latency of existing slow links. The use is increasing rapidly.

In addition, protocols for IP telephony are being standardized into H.323 and Session Initiation Protocol (SIP) protocols, respectively, led by the International Telecommunications Union (ITU) and the Internet Engineering Task Force (IETF). Is a standard for transmitting the data through a packet switched network (H.323 network). It specifies the system components (components), control messages, and functions of components, and is a home managed by a gatekeeper in the corresponding H.323 network. A home zone is a set of terminals, gateways, and multipoint controllers, and is composed of a plurality of subnets.

The conventional IP telephones described above are handoffs that allow users to continuously maintain a call even when a user moves from one subnet to another within the same zone as cellular phone demand and wireless local area network (LAN) environment increases. In other words, mobility is supported. To support this handoff, when the subnet of a mobile terminal, which is an IP phone, is changed, an IP host must be able to acquire a new network access point, and seamless roaming during a call is possible. roaming must be provided.

At this time, the protocols supporting mobility for IP hosts include IETF's Mobile IP, which is a Home Agent and an Out-of-Zone Agent corresponding to the network layer of Open Systems Interconnetion (OSI). A mobile agent called Foreign Agent tunneled and exchanged messages received by a mobile terminal, thereby supporting mobility without any change in the H.323 network.

However, in the conventional H.323 network, the mobile IP is not suitable for real-time communication due to a long delay time when exchanging messages between a home agent and an out-of-zone agent, and only a mobile IP that does not have a connection base in a connection-based mobile terminal alone. Not suitable for use

Therefore, the 'H.323 Annex H' standard has been enacted in the past to support the mobility of the mobile terminal, which supports handoff through mobile IP and conference extension, which roams within one zone. The attempted IP phone recognizes that its network access point has been changed through an entity of the network layer such as a mobile IP, acquires a new IP (Care of Address, COA), and then conferences through a join process. Participate in to receive handoff support.

However, in the above-described H.323 network, signaling for extending a multiparty conference is a signaling method that is essentially supported only in a multipoint controller, and may not be supported in a terminal or a gateway. In particular, a gatekeeper managing one zone may be used. In an environment that supports only multipoint controllers and does not support multipoint processors, multiparty conferencing signaling through gatekeepers introduces complex signaling to mobile terminals, which are IP phones, which adds to the load, resulting in handoff. There was a drawback to the long time.

That is, in the conventional H.323 network, a handoff signaling processing procedure through a multi-party conference will be described in detail with reference to FIG. 1 as follows. Here, a mobile terminal located in a predetermined subnet in a zone is referred to as 'first'. A first mobile terminal that has moved to another subnet in the same zone after establishing a connection with a fixed terminal that is a call target will be referred to as a 'second mobile terminal'.

First, a second mobile terminal moving to another subnet in the zone and attempting to roam acquires a new IP address (COA) by recognizing that its network access point has been changed through the mobile IP, and then uses the obtained IP address. The gatekeeper is requested to register (step S1), and the user is allowed to register his IP address again with the obtained IP address (step S2).

Then, the second mobile terminal performs an AdmissionRequest / AdmissionConfirm message processing with the gatekeeper for handoff signaling corresponding to the new IP address (steps S3 and S4). The join setup message is transmitted to the gatekeeper (step S5), and the connection message is received from the gatekeeper (step S6).

Thereafter, the second mobile terminal transmits a terminal input / output set (Terminal CapabilitySet) message to the gatekeeper (step S7), and receives the corresponding terminal input / output set response message from the gatekeeper (step S8). Based on the terminal I / O set message received from the second mobile terminal, a selected communication mode (SelectedCommunicationMode) of the corresponding conference node is generated and transmitted to the second mobile terminal through a response message.

After receiving the corresponding terminal input / output set response message, the second mobile terminal transmits a master slave decision message to the gatekeeper (step S9), and receives the corresponding master slave decision response message from the gatekeeper (step S9). S10) The master slave decision response message is retransmitted to the gatekeeper (step S11).

Accordingly, the gatekeeper transmits a multipoint controller location indication message indicating that the mobile terminal is a multipoint controller to the second mobile terminal (step S12), and then informs that the corresponding conference has been extended from end-to-end to multiple points. The multipoint conference message is transmitted to the first mobile terminal and the second mobile terminal (step S13).

The gatekeeper transmits a terminal number assignment message to be used in a synchronization source identifier (SSRC) field of a Real-time Transport Protocol (RTP) packet to the second mobile terminal (step S14).

At this time, the counterpart terminal and the second mobile terminal transmit a terminal list request message to the gatekeeper to request a list of terminals in the meeting (step S15), and the gatekeeper includes a list of terminals in the current meeting. After transmitting the terminal list response message to the counterpart mobile terminal and the second mobile terminal (step S16), a communication mode command message is transmitted to the counterpart terminal, the first mobile terminal, and the second mobile terminal to inform the new communication mode. (Step S17).

Meanwhile, the counterpart terminal and the second mobile terminal, which have received the multi-point conference message, transmit a LogLogicalChannel CloseLogicalChannel message to the gatekeeper in order to close the existing communication channel as the communication mode command message is transmitted ( Step S18), a logical channel open (OpenLogicalChannel) message is transmitted to a new communication channel, that is, a communication channel corresponding to the communication mode command message received from the gatekeeper (step S19). In this case, the logical channel open message is transmitted to the new communication channel. When transmitting the data, each of the terminals in the multi-unicating mode can exchange communication with the logical channel opening message and the logical channel opening response message.

In this case, since the first mobile terminal does not receive the logical channel open message, the corresponding mobile station, the second mobile terminal, and the gatekeeper may perform signaling for handoff by considering the corresponding response message. do.

Then, when the handoff is completed through the message exchange between each terminal, the first mobile terminal sends a session command end (EndsessionCmd) message to leave the meeting (step S20), the gatekeeper is the first mobile terminal Recognizing that the H.245 connection is released due to the departure of the conference, after transmitting a terminal left conference (terminalleft conference) message to the opposite terminal and the second mobile terminal (step S21), operating the terminals in the conference in end-to-end mode. The multipoint conference cancellation message is transmitted (step S22).

Then, the first mobile terminal completes the handoff by transmitting a release completion message to the gatekeeper and sending a delete request (DeleteRequestState) message (step S23).

As described above, the handoff for the mobile terminal, which is an IP phone proposed by the conventional 'H.323 Annex H', is supported through the mobile IP and the multi-party conference, and the new IP address is assigned to the mobile terminal through the mobile IP. It is suitable for global roaming due to the long time required for handoff due to the allocation of the COA and additional H.323 signaling, but it is not suitable for the local roaming environment that is frequently moved.

In addition, multi-party conference signaling in an environment where a gatekeeper that manages one zone and performs call control in a zone supports only a multipoint controller, but does not support a multipoint processor, causes complex signaling to a mobile terminal. In addition, there is a disadvantage in that the handoff time is increased, and the signaling for performing the handoff through the multi-party conference is considered for the allocation of the communication channel in consideration of the mobile terminal before moving to another non-existent subnet. The exchange of messages has the disadvantage that the handoff signaling of the mobile terminal is not transparent to other multiparty conference signaling.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object thereof is that if a terminal can process an empty input / output set message in an H.323 network, the gatekeeper becomes a third party to pause and restart the terminal. By using the routing function to handle the handoff, it is possible to handle the handoff of the terminal that does not support the conference mode, and at the same time, it is possible to perform a simpler and faster handoff process than the handoff through the conventional conference mode. .

1 is a diagram illustrating a handoff processing procedure through a multiparty conference in a conventional H.323 network.

2 illustrates an H.323 home zone managed by a gatekeeper in the present invention.

3 is a diagram illustrating a handoff processing procedure of a gatekeeper in an H.323 network according to the present invention.

Explanation of symbols on the main parts of the drawings

FT: opponent's terminal GK: gatekeeper

MT1: first mobile terminal MT2: second mobile terminal

A feature of the present invention for achieving the above object is the process of pausing the first mobile terminal and the other terminal when the first mobile terminal in a specific subnet in the zone moves to another subnet; Creating a call with a new IP of a second mobile terminal moved to another subnet, and then removing the connection with the first mobile terminal; The present invention provides a handoff processing method using a gatekeeper, the method comprising releasing a pause of the counterpart terminal and completing a handoff by rerouting a media channel with the new IP address.

Here, the process of pausing the first mobile terminal and the counterpart terminal may include: requesting registration by obtaining a new IP address by a second mobile terminal moving to a different subnet; Allowing registration to the second mobile terminal and transmitting an empty input / output set message to the counterpart terminal and the first mobile terminal; Transmitting an input / output set response message and a logical channel closure message to a gatekeeper by a counterpart terminal and a first mobile terminal receiving the empty input / output set message; And transmitting a logical channel closure response message to the counterpart terminal and the first mobile terminal to pause the counterpart terminal and the first mobile terminal.

The call setup with the second mobile terminal transmits a setup message to the second mobile terminal, performs a permission request / permit confirmation message processing, and then receives a call progress / call / connection message from the second mobile terminal. And receiving and setting the connection, and removing the connection with the first mobile terminal by removing a resource such as a socket allocated to the first mobile terminal by removing a connection by sending a session command end message to the first mobile terminal. The pause release of the counterpart terminal may be performed by transmitting an input / output set message of the second mobile terminal to the counterpart terminal to release the pause.

In addition, the above-described handoff processing method using a gatekeeper, the method comprising: checking whether the second mobile terminal supports tunneling to transmit an input / output set message of the second mobile terminal to the counterpart terminal; If the second mobile terminal does not support tunneling, the second mobile terminal attempts a TCP connection with the address of the second mobile terminal, transmits an input / output set message of the other terminal, and receives the input / output set message of the second mobile terminal to the counterpart terminal. Transmitting; And if the second mobile terminal supports tunneling, directly receiving an input / output set message of the second mobile terminal and transmitting the received message to the counterpart terminal.

Further, in the process of completing the handoff by rerouting the media channel with the new IP address, the counterpart terminal and the second mobile terminal perform general signaling to a predetermined control channel through a gatekeeper to establish a logical channel with the new IP address. After switching to complete the handoff is characterized in that to perform the media communication.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the H.323 network according to the present invention, a handoff is performed by using a H.323 third party initiated pause and rerouting function, which is initiated by a third party gatekeeper. The managing H.323 home zone is a configuration in which subnets connected through a plurality of IP routers (not shown) are controlled and managed by one gatekeeper (GK), as illustrated in FIG. 2. Has

Here, assuming that the opposite terminal FT may be a fixed H.323 IP host or a mobile H.323 IP host, and the opposite terminal FT and the first mobile terminal MT1 cannot participate in the multiparty conference. When handoff is performed to the mobile terminal MT2, it is recognized that only the counterpart terminal FT and the first mobile terminal MT1 are end-to-end in the conference.

In addition, roaming in an H.323 network includes inter-zone roaming and intra-zone roaming. Since dual inter-zone roaming requires communication between gatekeepers, the present invention uses mobile IP. The handoff supported by intra zone roaming switching the communication channel to the assigned new IP address (COA) will now be described.

In addition, the third party-driven suspend and rerouting function used in the present invention is a function that must be supported by an H.323 entity that is H.323 v2 (version 2) or higher. If the gatekeeper (GK) that manages the service becomes a third party and supports suspension and rerouting, additional services such as call transfer are also available for terminals not supporting 'H.450'. It can be used for voice answering service that connects the relevant call to Music Of Hold when the agent is busy in the call center and then reroutes the call to the agent when the agent ends the call. .

In the present invention, the gatekeeper pauses the first mobile terminal MT1 and the counterpart terminal FT before moving to another subnet, and then adds a new IP to the second mobile terminal MT2 moved to the other subnet. In H.323 network, terminals operate in the multi-conference mode by assigning addresses to set up calls, unpausing the other party's FT, and rerouting the media channels with new IP addresses. If not, the gatekeeper GK supports pausing and rerouting so that handoff can be performed.

Meanwhile, the handoff processing procedure of the gatekeeper in the H.323 network according to the present invention will be described with reference to FIG. 3.

First, when the first mobile terminal MT1 located in a specific subnet of a zone managed by the gatekeeper GK moves to another subnet while establishing a call channel with the other terminal FT, the first mobile terminal MT1 moves to another subnet. 2 The mobile terminal MT2 recognizes that its network access point has been changed through the mobile IP, acquires a new IP address COA, and requests the registration to the gatekeeper GK again using the obtained IP address ( Step S31), the user is allowed to re-register his IP address with the obtained IP address (step S32).

The gatekeeper GK has an empty input / output set (EmptyCapabilitySet) message, that is, a sequence number and a protocol identifier, to stop the counterpart terminal FT and the first mobile terminal MT1. An I / O set message having no input / output descriptor is transmitted to the counterpart terminal FT and the first mobile terminal MT1 (step S33), and the counterpart terminal FT and the first mobile terminal receiving the empty input / output set message are transmitted (step S33). The MT1 transmits an input / output set response message and a logical channel closure message to the gatekeeper GK (steps S34 and S35).

Accordingly, the gatekeeper GK transmits a logical channel closure response message to the counterpart terminal FT and the first mobile terminal MT1 to pause the counterpart terminal FT and the first mobile terminal MT1 ( Step S36).

Meanwhile, the gatekeeper GK transmits an empty input / output set message to the counterpart terminal FT and performs a second setup message for setting the Q.931 channel to perform a handoff to the second mobile terminal MT2. After transmitting to the mobile terminal MT2 (step S37), a permission request / permit confirmation message processing is performed with the second mobile terminal MT2 (steps S38 and S39), and the call is received from the second mobile terminal MT2. A call proceeding / alerting / connection message is received (step S40). At this time, the gatekeeper GK transmits a session command end message to the first mobile terminal MT1 (step S41). In addition, by releasing resources such as sockets allocated to the first mobile terminal MT1, the connection with the first mobile terminal MT1 is removed, and information of the first mobile terminal MT1 is deleted from the conference node.

The gatekeeper GK checks whether the second mobile terminal MT2 that has transmitted the connection message supports tunneling, and if the second mobile terminal MT2 does not support tunneling, the second mobile terminal MT2. Attempts a TCP connection with the H.245 address of the UE. Accordingly, the second mobile terminal MT2 accepts a TCP connection and receives an input / output set message of the other terminal FT from the gatekeeper GK. Is transmitted (step S42), and its own input / output set message is transmitted to the gatekeeper GK (step S43).

However, when the second mobile terminal MT2 supports tunneling, the second mobile terminal MT2 directly transmits its input / output set message to the gatekeeper GK (step S43), and the gatekeeper GK moves the second terminal to the counterpart terminal. The input / output set message received from the terminal MT2 is transmitted (step S44), and the corresponding terminal FT is temporarily suspended to resume operation.

At this time, the second mobile terminal MT2 transmits an input / output set response message to the gatekeeper GK (step S45), and the counterpart terminal FT and the second mobile terminal MT2 released in the pause state are gated. By performing general H.245 signaling to a predetermined control channel through a keeper GK to connect a new logical channel, handoff is completed and media communication can be performed through the logical channel.

Here, briefly describing the general H.245 signaling procedure, when the counterpart terminal FT and the second mobile terminal MT2 respectively transmit a terminal input / output set response message to the gatekeeper GK, the corresponding gatekeeper GK ) Transmits the terminal input / output set response message received from the counterpart terminal FT to the second mobile terminal MT2, and the terminal input / output set response message received from the second mobile terminal MT2 is transmitted to the counterpart terminal FT. Done.

When the counterpart terminal FT and the second mobile terminal MT2 respectively transmit a master slave determination message to the gatekeeper GK, the gatekeeper GK transmits a master slave determination response message to the counterpart terminal FT. ) And the second mobile terminal MT2, respectively, and the corresponding terminal FT and the second mobile terminal MT2 retransmit the received master slave decision response message to the gatekeeper GK.

Subsequently, when the counterpart terminal FT and the second mobile terminal MT2 transmit a logical channel open message to the gatekeeper GK, the gatekeeper GK opens the logical channel received from the counterpart terminal FT. The message is transmitted to the second mobile terminal MT2, and the logical channel open message received from the second mobile terminal MT2 is transmitted to the counterpart terminal FT.

Accordingly, when the counterpart terminal FT and the second mobile terminal MT2 transmit a logical channel open response message to the gatekeeper GK, the gatekeeper GK transmits the logical channel received from the counterpart terminal FT. The open response message is transmitted to the second mobile terminal MT2, and the logical channel open response message received from the second mobile terminal MT2 is transmitted to the counterpart terminal FT, thereby completing the handoff. In this case, media communication is performed by switching the communication channel to the RTP address.

As described above, in the H.323 network according to the present invention, if the counterpart terminal performing media communication with the mobile terminal can process the empty input / output set message, the gatekeeper uses a third party-driven pause and rerouting. By providing a handoff for the mobile terminal, a mobile terminal that does not support the multi-party conference mode can be provided with the handoff, and at the same time, a simpler and faster handoff process is possible than the handoff through the conventional multi-party conference mode.

In addition, the embodiments according to the present invention are not limited to the above-described embodiments, and various alternatives, modifications, and changes can be made within the scope apparent to those skilled in the art.

As described above, according to the present invention, if a terminal can process an empty input / output set message in an H.323 network, the gatekeeper becomes a third party and processes the handoff by using a pause and rerouting function of the terminal driven by the third party. A handoff of a terminal that does not support a multi-party conference mode can also be handled, and a simpler and faster handoff process is possible than a handoff through a conventional multi-party conference mode.

Claims (7)

Pausing the first mobile terminal and the counterpart terminal when the first mobile terminal in a specific subnet in the zone moves to another subnet; Creating a call with a new IP of a second mobile terminal moved to another subnet, and then removing the connection with the first mobile terminal; And releasing the pause of the counterpart terminal and rerouting the media channel to the new IP address to complete the handoff. The method of claim 1, The process of pausing the first mobile terminal and the counterpart terminal may include: obtaining a new IP address and requesting registration by a second mobile terminal moving to a different subnet; Allowing registration to the second mobile terminal and transmitting an empty input / output set message to the counterpart terminal and the first mobile terminal; Transmitting an input / output set response message and a logical channel closure message to a gatekeeper by a counterpart terminal and a first mobile terminal receiving the empty input / output set message; And transmitting a logical channel closure response message to the counterpart terminal and the first mobile terminal to pause the counterpart terminal and the first mobile terminal. The method of claim 1, The call setup with the second mobile terminal transmits a setup message to the second mobile terminal, performs a permission request / permit confirmation message, and receives a call progress / call / connection message from the second mobile terminal. Handoff processing method using a gatekeeper, characterized in that the setting. The method of claim 1, In the connection removal with the first mobile terminal, a handheld using a gatekeeper, which releases a connection such as a socket allocated to the first mobile terminal by removing a connection by sending a session command end message to the first mobile terminal. Off processing method. The method of claim 1, The pause cancellation of the counterpart terminal is performed by sending an input / output set message of the second mobile terminal to the counterpart terminal to release the pause. The method of claim 5, Checking whether the second mobile terminal supports tunneling to transmit an input / output set message of the second mobile terminal to the counterpart terminal; If the second mobile terminal does not support tunneling, the second mobile terminal attempts a TCP connection with the address of the second mobile terminal, transmits an input / output set message of the other terminal, and receives the input / output set message of the second mobile terminal to the counterpart terminal. Transmitting; If the second mobile terminal supports tunneling, directly receiving an input / output set message of the second mobile terminal and transmitting the received message to a counterpart terminal. The method of claim 1, In the process of completing the handoff by rerouting the media channel with the new IP address, the counterpart terminal and the second mobile terminal switch the logical channel to the new IP address by performing general signaling to a predetermined control channel through a gatekeeper. A handoff processing method using a gatekeeper, characterized in that the media communication is performed after the handoff is completed.