KR100702457B1 - Multiple mode terminal supporting handoff between heterogeneous network and the handoff method thereof - Google Patents

Abstract

The present invention relates to a multi-mode terminal and a network switching method for supporting network switching between heterogeneous networks.

The multi-mode terminal according to the present invention is a mode control unit for controlling connection switching between a plurality of communication networks using network state monitoring information, a plurality of protocols and data communication services designed to provide a data communication service suitable for the plurality of communication networks The application service unit including a program of the common control unit for performing the connection switching between the heterogeneous network by the connection switching command of the mode control unit, and resetting the transmission path of the data packet according to the network switching result, and the terminal It includes a number of device drivers to have a function suitable for data services in a communication network.

Network switching, multiple modes, code-devision multiple access (CDMA), wireless broadband internet

Description

MULTIPLE MODE TERMINAL SUPPORTING HANDOFF BETWEEN HETEROGENEOUS NETWORK AND THE HANDOFF METHOD THEREOF}

1 is a diagram illustrating a platform mounted in a multi-mode terminal according to an embodiment of the present invention.

2 is a diagram illustrating a data transmission path through a common connection of a multi-mode terminal according to an embodiment of the present invention.

3 is a diagram illustrating a mode control manager according to an exemplary embodiment of the present invention.

4 is a diagram illustrating a communication environment to which a multi-mode terminal can access according to an embodiment of the present invention.

5 is a flowchart illustrating an initial network access procedure of a multi-mode terminal according to an embodiment of the present invention.

6 is a flowchart illustrating a network switching process in a multi-mode terminal according to an embodiment of the present invention.

The present invention relates to a multi-mode terminal and a network switching method for supporting network switching between heterogeneous networks. More specifically, multi-mode enables interworking between various heterogeneous communication networks to provide seamless data communication services without being affected by changes in the wireless access environment in various communication networks based on mobile IP (internet protocol). The present invention relates to a terminal and a method for switching a network thereof.

Recently, as users' demands and interests in using the Internet in a mobile environment increase, communication with a mobile terminal, a laptop, a personal digital assistant (PDA), and the like, unlike a conventional data communication service using a wired network Wireless communication capable of bidirectional communication anytime, anywhere, regardless of time and place using a terminal is rapidly emerging.

As the wireless communication network has moved to the next generation, a data communication technique using a code-division multiple access (CDMA) mobile communication network based on the third generation network has been developed as a new type of wireless network. It is. However, the data communication through the mobile communication network is relatively slow compared to the high-speed wired Internet network, while the usage fee is high, there is a limit on its use.

In addition, the conventional wireless LAN (WLAN) method such as IEEE 802.11 is applicable to a variety of areas, such as the network connection between the building, the area where the mobility of the terminal is required, or where cable wiring is difficult. Wireless LANs provide a data communication method capable of wireless communication within a short distance around a fixed access point (AP), but this does not provide mobility of a mobile subscriber station (MSS). It was limited to supporting short-range data communication by wireless rather than wired. At present, in order to solve the above-described problems, a wireless broadband system (WiBro), which combines a feature capable of high-speed and high-quality data communication services of a wireless LAN with a wide range of service coverage of a mobile communication network, has been developed. .

The wireless portable Internet system is a technology promoted by the IEEE 802.16 group and guarantees mobility of 60km / h within 1km using the frequency of 2.3GHz band, and supports 3Mbps download and 1Mbps upload per subscriber.

However, while the wireless portable Internet system has the advantage of mobility and high speed data communication, its service area is narrow, and the mobile communication system cannot be provided with high speed service due to limited wireless capacity. Therefore, when a service and a terminal interworking with a mobile communication network and a wireless portable internet network are developed, a user can receive continuous data communication services in a wide area by making full use of the advantages of each network.

However, conventionally, since the mobile communication terminal and the wireless portable Internet terminal have been developed as separate models, respectively, there is a limit in that a user can be provided with a seamless high speed data communication service at a low price. Therefore, when the mobile communication service user enters the service area of the wireless mobile Internet network, it is desirable to switch to the mobile Internet service, which has a high-speed service. It's a service plan. In order to provide such a service, there is a need for a composite terminal capable of simultaneously supporting data communication between a mobile communication network and a portable Internet network.

An object of the present invention is to provide a multi-mode terminal and a network switching method that enables seamless data communication through network switching between a plurality of heterogeneous networks providing an IP-based data communication service.

In order to solve this problem, according to an aspect of the present invention, a mode control unit for controlling the connection switching between a plurality of communication networks using network state monitoring information, a protocol and data for providing a data communication service suitable for the plurality of communication networks An application service unit including a plurality of programs designed to perform a communication service, and performing connection switching between heterogeneous networks according to a connection switching command of the mode control unit, and resetting a transmission path of a data packet according to a network switching result. There is provided a multi-mode terminal for supporting connection switching between heterogeneous networks including a common connection unit supporting a data communication service of a service unit and a plurality of device drivers for allowing the terminal to have a function suitable for data services in the plurality of communication networks. .

In this case, the mode controller selects a communication network capable of providing an optimal communication service to a terminal from among a plurality of accessible communication networks based on the network state monitoring information, and transmits a connection switching command to the common connection unit. And a plurality of communication network connection modules for controlling the driving of the plurality of device drivers and performing an authentication procedure for the terminal in order to switch the connection to the network selected by the control module.

According to another feature of the invention, the platform mounted on the multi-mode terminal determines whether to set up the automatic network connection, when the automatic network connection is set, the platform to select the optimal network based on the received field strength information A step in which the platform generates a transmission path of a data packet for the selected communication network; and the platform assigns a mobile IP and performs protocol data transmission by changing a protocol parameter so as to be suitable for the communication network. Provided are a network switching method in a multi-mode terminal for providing seamless data communication to a multi-mode terminal equipped with a platform supporting network switching between communication networks.

According to still another aspect of the present invention, there is provided a computer-readable recording medium having recorded thereon a program for performing the above method.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification. In addition, when a part is said to "include" a certain component, it means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, the module described in the specification means "a block configured to change or plug in a system of hardware or software", that is, a unit or a block that performs a specific function in hardware or software. do.

First, a platform supporting network switching between heterogeneous networks mounted in a multi-mode terminal according to an embodiment of the present invention may be implemented in the form of software, hardware, or module.

1 is a diagram illustrating a platform mounted in a multi-mode terminal according to an embodiment of the present invention. As shown in FIG. 1, a platform for a multi-mode terminal according to an embodiment of the present invention includes a control plane 100 and a data plane 200. FIG. 1 illustrates a platform providing interworking between a code-division multiple access (CDMA) communication network and a wireless broadband internet (WiBro) communication network. A description will be given based on a platform that enables interworking between a CDMA network and a WiBro network.

The control plane 100 includes a mode control unit 110, an Internet protocol (IP) mobility support unit 120, and a protocol management unit 130. The control plane 100 controls the transmission of data made in the data plane 200 and between heterogeneous communication networks. It supports not only network switching, ie vertical handover but also horizontal handover in the same network.

The mode control unit 110 automatically or manually uses the monitoring result of the communication state including the received electric field strength, data transmission rate, transmission error rate, etc. of the communication networks being serviced in the area where the terminal on which the platform is mounted is present. Controlling of connection switching. The configuration and function of the mode controller 110 will be described in detail below.

The IP mobility support unit 120 does not need to readjust IP even when a connection switch to another network is made according to the network switching command from the mode controller 110, and the IP mobility support unit 120 may not perform the data transfer procedure within the data plane 200. In order to eliminate the need for a parameter change procedure in accordance with the movement of the IP, it serves to provide a mobile IP (mobile IP). In the case of network switching, in order to support IP mobility when the mobile terminal switches network connection, the communication terminal is allocated an IP from the network to which the mobile terminal is originally connected, and then communicates with the mobile station. After receiving the address and COA, ask the home agent (HA) of the original network to bind the FA's address, encapsulation of the IP packet that HA was routing, and deliver it to the FA. Tunneling, the FA receives the IP packet, strips the header overlaid with the FA address, and passes the original IP to the upper application layer.

The IP mobility support unit 120 performs the function of supporting the mobile IP, so that even when the connection is switched to another communication network, the IP mobility support unit 120 uses the IP used in the previously connected communication network in data transmission and reception made in the data plane 200 of the terminal. By enabling communication, the IP-based network connection of the upper application layer can be maintained. Since the IP mobility support unit 120 performing such a function does not need to go through a separate process for IP movement such as IP resetting during network switching, it ensures mobility of terminals between IP-based heterogeneous communication networks.

The protocol manager 130 may preset protocol parameter information so that an optimal data communication service may be provided according to a change in communication state of a network to which a terminal is currently connected and a change in communication state due to a change of connection between heterogeneous networks. Based on this, the protocol layer-specific properties of the data plane 200 are changed in real time to optimize communication performance. That is, the protocol manager 130 embeds protocol parameters including communication speed and quality of service (QoS) rules for a plurality of networks, so that when a connection is switched between each network, The protocol parameters in the data plane 200 are reset in real time according to the characteristics.

For example, when the connection to the heterogeneous network is performed, the protocol manager 130 may determine the maximum segment size (MSS) and congestion window of the transmission control protocol (TCP). Resize parameters such as size, size of receive window, re-transmission time-out, round-trip time (RTT), etc. to suit the characteristics of data communication supported by each network. For internet protocol (IP), parameters can be set to maintain the quality of service (QoS) required by each network, and for device drivers, queue size and bandwidth can be adjusted. .

The data plane 200 supports data communication in an IP-based multi-network, and includes a first layer 210 including a hardware interface and a device driver to function as a communication terminal suitable for each network. The second layer 220, the third layer 230 for performing connection switching to each communication network, the fourth layer 240 including a communication protocol including TCP / IP, an application program designed to perform a specific task. It includes a fifth layer 150 including a. The data plane 200 having such a configuration receives a network switching command transmitted from the control plane 100 to perform connection with each hardware interface through the third layer 230, and performs connection switching between heterogeneous networks. The communication path may be reset without changing the fourth layer 240 and the fifth layer 250.

The first layer 210 includes a CDMA hardware interface (H / W interface) 211 and a WiBro hardware interface 212 so that the terminal can function as a CDMA terminal and the terminal is a WiBro terminal. A hardware chip (not shown) for functioning with a platform according to an embodiment of the present invention is established, operating or maintaining a physical link between systems, and defining electrical, mechanical, procedural and functional aspects. In this case, the hardware chip portion that is matched with the first layer 210 of the platform may be a form in which the functions of heterogeneous networks are implemented in one chip, or may be configured to insert and use each hardware chip in the form of a card. have.

The second layer 220 guarantees independent operation of the first layer of various communication schemes, and for this purpose, an embodiment of the present invention includes a CDMA device driver 221 and a WiBro device driver 223. . The CDMA device driver 221 and the WiBro device driver 223 are modules that are a link between the hardware and the operating system application program, and allow the hardware component to perform a proper function as desired under the operating system. That is, the second layer 220 allows the terminal equipped with the platform according to the embodiment of the present invention to function as a terminal suitable for the characteristics of each communication network when the connection is switched to each network.

In addition, the CDMA device driver 221 and the WiBro device driver 223 periodically check the change state of the received electric field strength in the corresponding network and provide it to the mode controller 110, whereby the received electric field strength of the corresponding network starts to decrease. At this point in time or when the received field strength reaches a preset lower limit, connection to another network can be made. In addition, the CDMA device driver 221 and the WiBro device driver 223 periodically collect communication status information including the data transmission rate and the data transmission error rate in each communication network.

In addition, the second layer 220 supports a function of compressing a header portion of a data packet, a password authentication protocol (PAP), or a challenge-handshake authentication protocol (CHAP). The protocol may further include a point-to-point protocol 222. The PPP 222 wraps an IP packet received from an upper layer or a lower layer with a point to point protocol header, and forwards it to a PPP server in a CDMA network, thereby using one or more IP addresses at one point. Connect to the Internet to enable communication.

The third layer 230 includes a common link module 231, and when connecting to each communication network, connection control procedures for performing connection switching and routing in data communication are independent of hardware and applications. By doing so in a common way, transparency is ensured in the upper layers. The third layer 230 allows connection switching with each device driver in the second layer 220 according to the connection switching command transmitted from the control plane 100.

 The common connection unit 231 in the third layer 230 performs the above-described function, receives the data packet from the fourth layer 240, and delivers the packet to the device driver of the currently connected network. At this time, due to the common connection unit 231, the fourth layer 240 and the fifth layer 250 separately specify an identification code for specifying whether to transmit data using a CDMA network or a WiBro network. It is possible to provide a continuous data communication service to a user of the terminal without adding an operation such as inserting into a data packet.

The common connection unit 231 receives information on the currently connected network from the mode control unit 110 at the initial connection, maintains the connection state, and receives a network switching command from the mode control unit 110. Connection switching is performed by switching the data connection path via the driver. At this time, the common connection unit 231 minimizes service interruption by simultaneously maintaining the connection with the two types of device drivers 221 and 223 until the switching is completed in the process of switching between heterogeneous networks.

The common connection unit 231 includes a virtual device driver to control the transmission of data packets between the upper layer and the lower layer through the common connection unit 231. When transmitting the data packet to the outside of the terminal, the MAC address of the source and the target is required for data processing in the fourth layer 240. In this case, the common connection unit 231 is currently present. By copying the MAC address of the selected device driver and providing it to the fourth layer 240 as the MAC address of the virtual device driver, the fourth layer 240 does not specify which type of data communication should be made, and the common connection unit 231. It can process data packet using MAC address received from. When the data packet generated through the process is received from the fourth layer 240, the common connection unit 231 determines which device driver is currently connected and outputs the packet to the queue of the corresponding driver.

On the contrary, when a packet is input to a specific device driver in the second layer 220 through the hardware interface of the first layer 210 from the outside of the terminal, the common connection unit 231 transmits the data packet to the upper layer. After setting the device driver that received the packet to the common connection unit 231, the packet is transmitted to the upper layer.

2 illustrates a flow and control process of a data packet through a common connection unit 231 according to an embodiment of the present invention. As shown in FIG. 2, if a multi-mode terminal according to an embodiment of the present invention is currently connected to a CDMA network, the data packet may include an application service 252, a TCP / IP 241, 243, a common access unit 231, and a CDMA network. The device driver 221 is transmitted along the path of the CDMA hardware interface 211. In contrast, if the communication terminal is currently connected to the WiBro network, the data packet is applied to the application service 252, TCP / IP (241, 243), and common. Communication is performed along the path of the connection unit 231, the WiBro device driver 223, and the WiBro hardware interface 212. That is, when the common connection unit 231 receives a network switching command from the control module 111, the common connection unit 231 transmits and receives data packets transmitted and received to the CDMA device driver 221 through the WiBro device driver 223 through the above-described process, or Switch the forwarding path of the data packet in the reverse direction.

In addition to the data transmission / reception function, the common connection unit 231 records data usage statistics information of each device driver of the second layer 220 in order to support the network connection switching function of the control plane 100. Additionally.

In the embodiment of the present invention, the common connection unit 231 is configured to replace the actual device driver of each network constituting the lower layer by performing a function of a virtual device driver. By modifying the header of the data packet, the upper layer configuration can allow continuous IP-based data communication without modification.

The fourth layer 240 includes an internet protocol (IP) 241, an internet control message protocol (ICMP) 242, a TCP 243, and a user datagram protocol (UDP) 244. And reliable data communication. That is, the fourth layer 240 functions similar to the network layer and the transport layer of the seven layers of open systems interconnection.

The fifth layer 250 is a layer including a program designed to perform a specific service. The fifth layer 250 includes an application service unit 252 and a real-time support unit 251 that modularize such a program. The application service unit 252 may include various application programs such as an MP3 codec, an H.263 codec, a web browser, a media player, and a video communication program.

In the embodiment of the present invention, the protocols 241 to 244, the real time support unit 251, and the application service unit 252 in the fourth layer 240 and the fifth layer 250 operate as separate components, respectively. However, it does not necessarily need to exist as an independent separate function block, but may be included in the application service unit 252 and driven. In addition, the embodiment of the present invention has been described with respect to the platform that supports the interworking between the CDMA network and WiBro network, but can also support interworking between heterogeneous communication networks providing IP-based data communication services.

3 is a diagram illustrating a configuration of a mode control management unit according to an exemplary embodiment of the present invention. As shown in FIG. 3, the mode control manager 110 according to an embodiment of the present invention includes a control module 111, a profile management module 112, a network state monitoring module 113, a WiBro network connection module 114, CDMA network access module 115 is included.

The platform according to an embodiment of the present invention supports both automatic network switching in which a terminal automatically converts a network to which a terminal is automatically connected according to the analysis result of a network state, and manual network switching when a user wants to switch a network.

The control module 111 includes a network selection algorithm for selecting a network capable of performing an optimal data communication service according to a signal characteristic of a region in which a communication terminal supporting a platform according to an embodiment of the present invention is located, and automatic network switching. In this case, the network selection algorithm is repeatedly executed to select the access network. At this time, the network selection algorithm in the control module 111 compares the reception field strength measurement results of the CDMA device driver 221 and the WiBro device driver 223 with the information provided by the profile management module 112 to determine the specific network. If the received field strength exceeds a preset received field strength threshold for connection switching of the communication terminal, the network switching command may be issued. In addition, even when the terminal is initially connected, the network selection algorithm of the control module 111 may automatically select a suitable network according to the received electric field strength threshold.

The control module 111 transmits a command for switching the connection to the selected network as a result of the execution of the network selection algorithm to the common connection 231 in the data plane 200.

When manual network switching is set, the control module 111 receives and processes a connection to a specific network and a network switching command directly input from a user through a user interface 300 such as a graphical user interface (GUI). Then, the command for switching the connection to the network selected by the user is transmitted to the common connection unit 231.

When the connection is switched to a specific network, the control module 111 transmits a control signal to the IP mobility support unit 120 so that COA allocation, IP encapsulation, and IP tunneling are performed. Ensure seamless data communication. In addition, the control module 111 transmits network switching information to the protocol manager 130, thereby controlling the protocol manager 130 to reset parameters of protocols of the fourth layer 240 of the data plane in real time.

The profile management module 112 stores information input through the user interface 300. The user interface 300 may display the signal reception state information of each communication network on a screen and provide the same to the user. The user sets a network to be connected using this information, and the setting information is controlled by a control module ( And stored in the profile management module 112 via 111. In addition, the profile management module 112 stores and manages information on whether to switch the automatic or manual network input through the user interface 300 and the user's preferred network information to use the network in the control module 111. You can do that.

The network state monitoring module 113 reads the change information of the received electric field strength measured by the CDMA device driver 221 or the WiBro device driver 223 and provides the selected network information to the control module 111.

In the embodiment of the present invention, the profile management module 112 and the network state monitoring module 113 are described as operating as separate components from the control module 111, but need not necessarily exist as separate and distinct functional blocks. It may be included in the control module 111 and function.

When the control module 111 transmits a connection switching command to the WiBro network to the common connection unit 231, the WiBro connection module 114 initializes the WiBro device driver 223 to transmit a data packet transmitted from the common connection unit 231. When the access command is transmitted to the CDMA network again, the WiBro device driver 223 stops driving. The WiBro access module 114 performs a ranging procedure for correcting and matching timing, power, and frequency information between the terminal and the base station, performs initial ranging, and periodically periodically thereafter. Perform a ranging ranging procedure. In addition, the WiBro access module 114 performs an authentication procedure for providing a data service to a terminal using a device identifier such as a MAC address and a certificate of the terminal.

The CDMA access module 115, like the WiBro access module 114, performs initialization of the CDMA device driver 221, access to the CDMA network, and authentication processes.

FIG. 4 is a diagram illustrating a mobile communication environment to which a multi-mode terminal 400, which can support data communication in various communication networks, is equipped with a platform according to an embodiment of the present invention. As shown in FIG. 4, the multi-mode terminal 400 according to an exemplary embodiment of the present invention may support network selection and control of mobile IP in the control plane 100 and connection of a common connection 231 in the data plane 200. Through conversion, IMT-2000 (401), WLAN (402), digital video broadcast (DVB, 403), global system for mobile communication (GSM, 404) and personal area wireless communication ( It is possible to perform stable data communication in an IP-based multi-network system such as a wireless personal area network (WPAN, 405).

Under such a communication environment, M-commerce and location-based services are provided through a multi-mode terminal 400 equipped with a physical or software-defined interface and a protocol structure that can access various wireless systems. Various application services, such as based service (LBS), multimedia service, multimedia service, voice service, multimedia message service, mobile internet, and the like, may be provided.

5 is a flowchart illustrating an initial network access procedure of a multi-mode terminal equipped with a platform according to an embodiment of the present invention.

When power is applied to the communication terminal, after initial configuration of the terminal and initialization of communication protocol parameters are made, reception of a transmission signal in a communication network in which the terminal is located is started (S510).

When the terminal is initialized, the mode control unit 110 determines whether the user has automatically set the network selection with reference to the profile management module 112, and if the automatic connection is set, the profile management module 112. And a network selection algorithm based on the information of the network state monitoring module 113, thereby selecting a communication network capable of providing an optimal data service (S520 and S531). On the other hand, when the manual connection is established, the mode controller 110 controls the user interface 300 to provide a screen for network selection and receives a network selection signal from the user (S520, S530).

When the network selection is made through the above process, the mode controller 110 transmits the network selection result to the IP mobility support unit 120 and the protocol manager 130, and transmits a network switch command to the common access unit 231. It maintains the connection waiting state (S540).

The common connection unit 231 which receives the network switching command from the mode control unit 110 establishes a path for data communication by accessing the device driver of the selected network (S550).

The IP mobility support unit 120 allocates a COA to perform IP connection establishment for the terminal (S560).

The protocol manager 130 functions as a terminal for a specific network in the selected network and changes and sets the protocol parameters according to the characteristics of the corresponding network so as to maintain optimal data communication (S570).

Through this process, the data transmission path through the device driver for communication is established and the terminal assigned the IP address performs connection setup for data transmission and starts a data service (S580).

6 is a flowchart illustrating a network switching process in a multi-mode terminal according to an embodiment of the present invention.

If it is determined that the mode controller 110 is configured to automatically switch the network according to the change of the communication environment with reference to the profile management module 112, the CDMA device driver 221 received by the network state monitoring module 113. ) And the reception field strength measurement result of the WiBro device driver 223 to execute the network selection algorithm. If it is determined that the threshold value of the received electric field strength for network switching is exceeded as a result of executing the algorithm, the network switching command is transmitted to the common connection unit 231 (S610). In addition, in the case where the network switching is set manually, when the network switching command is input through the user interface 300, the mode controller 110 transmits a network switching command to the common connection unit 231 (S610). .

At the same time, the mode control unit 110 transmits a network selection result to the IP mobility support unit 120 and the protocol manager 130 so that the terminal maintains a connection waiting state (S620).

In order to minimize interruption of service, the common connection unit 231 temporarily establishes a data transmission path on both sides of the CDMA device driver 221 and the WiBro device driver 223 until the network switching is completed to maintain the dual connection state. (S630).

As such, while maintaining the dual connection state, the IP mobility support unit 120 allocates a COA to perform IP connection establishment for the terminal (S640).

The protocol manager 130 functions as a terminal for a specific network in the selected network, and sets protocol parameters according to characteristics of the corresponding network so as to maintain optimal data communication (S650).

Through this process, the data transmission path is established via the device driver of the switched network and the IP connection setting is terminated by using the COA. By starting the data service, the network switching process is terminated (S660).

In the embodiment of the present invention, only the connection switching between the CDMA network and the WiBro network has been described. However, the IP-based heterogeneous data communication system does not change the configuration of the upper layer of the common connection unit 231. By inserting device drivers and hardware interfaces that support services, network switching between various communication systems can be implemented.

In addition, in the embodiment of the present invention, the network switching between heterogeneous networks, that is, the vertical handover has been mainly described, but the horizontal handover due to the change of the received electric field strength due to the change of the position of the communication terminal in the same network Even if it is made, an IP-based data communication service may be provided through control procedures in the control module 111 and the protocol manager 130.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also the rights of the present invention. It belongs to the range.

As described above, according to the embodiment of the present invention, by controlling the transmission path of the data packet without changing the upper layer through the common connection that is not bound to the implementation of a specific function, it is possible to ensure mobility in the IP-based communication environment.

In addition, it is possible to minimize the interruption of the communication service by temporarily maintaining the connection to the heterogeneous network at the time of network switching, it is possible to support automatic network switching according to the change of communication network status and manual network switching according to the user's selection.

Claims (14)

In a terminal that supports connection switching between a plurality of communication networks, A mode control unit controlling connection switching between the plurality of communication networks using network state monitoring information; An application service unit including a protocol for providing data communication services suitable for the plurality of communication networks and a plurality of programs designed to perform data communication services; A common connection unit performing connection switching between heterogeneous networks according to a connection switching command of the mode control unit, and resetting a transmission path of a data packet according to a network switching result to support a data communication service of the application service unit; A plurality of device drivers for allowing the terminal to have a function suitable for data services in the plurality of communication networks; And And a protocol manager configured to change protocol parameters of the application service unit according to a change in the communication state associated with the connection change when the connection is switched between the plurality of communication networks. The method of claim 1, The network status monitoring information Terminal including at least one of the received electric field strength, data transmission rate or data transmission error rate of each communication network. The method of claim 2, The common connection part And a layer different from the plurality of device drivers and the application service unit and forming an upper layer of the device driver. The method of claim 3, The common connection part And a terminal for transmitting the MAC address of one device driver connected among the plurality of device drivers to the application service unit. The method of claim 4, wherein The plurality of device drivers Terminal for periodically checking the received electric field strength, data transmission rate and data transmission error rate of the communication network. The method of claim 5, Receiving a connection switch command from the mode control unit, the terminal further comprises a mobile IP (mobile IP) support terminal. The method of claim 6, The mode control unit A control module for selecting a communication network capable of providing an optimal communication service to the terminal from among a plurality of accessible communication networks based on the network state monitoring information, and transmitting a connection switch command to the common connection unit; And And a plurality of communication network connection modules for controlling the driving of the plurality of device drivers and performing an authentication procedure for the terminal, in order to switch the connection to the network selected by the control module. The method of claim 7, wherein The IP mobility support unit A terminal for receiving a network information selected by the mode control unit, and assigns a care of address (COA). The method of claim 8, When the common connection unit receives a network switching command from the mode control unit, A terminal assigned with a COA from the IP mobility support unit, and simultaneously maintaining a connection with the device driver of the previously connected communication network and the device driver of the communication network to be switched to until the protocol parameters of the protocol management unit are reset; The method of claim 9, The mode control unit, the IP mobility support unit and the protocol management unit forms one layer, and the application service unit, the common connection unit and the plurality of device drivers form a separate layer. The method according to any one of claims 1 to 10, The plurality of communication networks include a code-division multiple access network (CDMA) network and a wireless broadband internet network (WiBro). In the network switching method for providing a seamless data communication for a multi-mode terminal equipped with a platform that supports network switching between a plurality of communication networks, Determining, by the multi-mode terminal, whether to establish an automatic network connection; When the automatic network connection is established, selecting, by the multi-mode terminal, an optimal network based on received field strength information; Setting, by the multi-mode terminal, a transmission path of a data packet for the selected communication network; And And assigning a mobile IP to the multi-mode terminal and changing the protocol parameter to suit the corresponding communication network to perform data transmission. The method of claim 12, And maintaining, by the terminal, simultaneously accessing the previously connected communication network and the communication network to which the terminal is to be switched until the allocation of the mobile IP and the change of the protocol parameter are completed. A computer-readable recording medium having recorded thereon a program for realizing the method according to claim 12 or 13.

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