JP2004153542A - Agent program, radio terminal and hand-off control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agent program which can prevent data loss at the time of switching a communication system and a communication network and to provide a radio terminal and a hand-off control method. <P>SOLUTION: A multi-service terminal 170 receives radio signals of BS:130 and BS:150, and measures a reception level or reception quality. When the reception level or reception quality of the reception signal from BS:130 becomes not more than a threshold, the multi-service terminal 170 requests an address of a switch point router 120 from a management server 100 managing the address of the multi-service terminal 170. Connection is switched to BS 150 after the agent program for causing the switch router point 120 to perform a buffer control processing, a route control processing and a data transmission processing is read from a storage means and it is transmitted by receiving a reply of the address. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an agent program for preventing data loss when switching a communication system or a communication network, a wireless terminal, and a handoff control method.
[0002]
[Prior art]
2. Description of the Related Art As a technology for realizing handoff between different types of wireless systems, there is a protocol called Mobile IP, which is a technology in which a mobility function is added to Internet Protocol (hereinafter, referred to as IP). According to Mobile IP, the wireless terminal keeps a constant value regardless of the connection position of the wireless terminal to the Internet, and changes depending on the home address functioning as the identifier of the wireless terminal and the connection position of the wireless terminal to the Internet, It is managed by associating two IP addresses of a notice address indicating a connection position to the Internet. This association is performed by the management server connected to the link indicated by the home address.
That is, according to the function of Mobile IP, by using the home address, even when the wireless terminal moves from one subnet to another subnet, a TCP (Transport Control Protocol) connection can be maintained.
[0003]
This prior art will be described with reference to FIG. FIG. 14 is a configuration diagram of a conventional wireless communication system using Mobile IP. Now, consider a case where the wireless terminal 300 moves from the service area of the wireless communication system A to the service area of the wireless communication system B.
At this time, when the terminal 300 moves to the service area of the wireless communication system B, it informs the management server 320 that the terminal 300 has moved to the wireless communication system B. Upon receiving the movement notification of the terminal 300, the management server 320 changes the notice address to be added to the packet transmitted to the wireless terminal 300 from the address corresponding to the link of the wireless communication system A to the address corresponding to the link of the wireless communication system B. change.
After the process of adding the IP header, the packet is encapsulated, and the wireless terminal that has handed off during communication can continue data communication while establishing a TCP connection.
[0004]
[Non-patent document 1]
Fumio Teraoka "Standardization Trends of Mobile Communication Protocols on the Internet" IEICE Transactions, B Vol. J84-B No. 10 pp. 1746-1754
[0005]
[Problems to be solved by the invention]
However, in a Mobile IP environment, when a wireless terminal hands off from one subnet to another subnet, a switching delay occurs at a router at a point where a data transmission path before handoff and a data transmission path after handoff are switched, There is a problem that a packet during data communication is lost.
Specifically, when switching to the wireless communication system B, the wireless terminal 300 notifies the management server 320 as a home agent of the switching, but the management server 320 performs a process of assigning a care-of address and a process of encapsulating a packet. Smooth switching is not possible due to the processing delay time and the transmission delay time of the network. On the other hand, since the switching point router 310 cannot recognize that the wireless terminal 300 has moved from the wireless communication system A to the wireless communication system B, the communication system in which the wireless terminal 300 performs data communication is changed from the wireless communication system A to the wireless communication system A. Even after switching to the system B, if a data packet destined for the wireless communication system A is received, the packet is naturally forwarded to the wireless communication system A. However, since the wireless terminal 300 has moved from the service area of the wireless communication system A, this packet is not received by the wireless terminal 300. That is, here, there is a problem that the packet that should be delivered to the wireless terminal 300 is lost.
[0006]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an agent program, a radio terminal, and a handoff control method capable of preventing data loss even when a communication system or a communication network is switched. Is to provide.
[0007]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the invention according to claim 1 includes a buffer control process of storing data destined to a predetermined terminal in a buffer, and a transmission destination address of the terminal. Route control processing for changing a data transmission path to a changed destination address in response to a signal indicating that the data has been changed, and data transmission for transmitting data stored in the buffer to the changed destination address Is an agent program for causing a computer to execute processing.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, the data transmission processing includes, before changing the data transmission path, changing the data stored in the buffer in accordance with data to which the terminal is a destination. And transmitting the data to the destination address after the data transmission path change.
[0009]
According to a third aspect of the present invention, in the first aspect of the present invention, in the data transmission process, if the data destined for the terminal is real-time data, the real-time data is transmitted after the buffer control process. The process of transmitting to the destination address before the data transmission path change and the destination address after the data transmission path change, or, if the data destined for the terminal is non-real-time data, after the path control processing, It is characterized by comprising a process of transmitting data to a destination address after a data transmission path is changed.
[0010]
According to a fourth aspect of the present invention, a receiving means for receiving a radio signal from a first communication system connected via a network, and a radio signal from a second communication system around the first communication system. Second receiving means for receiving, measuring means for measuring the reception level or reception quality of the signals received from the first and second communication systems, and reception level or reception of the reception signals from the first communication system If the quality is equal to or less than a predetermined threshold, the management server managing the address of the wireless terminal connected to the network is branched to the first and second communication systems in the network. A requesting means for requesting an address of a repeater connected to the network at a point, and receiving the address of the repeater, receiving the address of the repeater according to any one of claims 1 to 3. Reads the agent program from the storage means for storing the E cement program, characterized by comprising a transmitting means for transmitting to said repeater, and a connection switching unit that switches a connection to the second communication system.
[0011]
The invention according to claim 5 is the invention according to claim 4, wherein the first data obtained by demodulating the radio signal from the first communication system and the first data obtained by demodulating the radio signal from the second communication system are used. The first data and the second data are compared with each other, and if the first data and the second data overlap, the data comparing means for discarding any one of the first data and the second data is further provided. It is characterized by having.
[0012]
According to a sixth aspect of the present invention, a receiving means for receiving the agent program according to any one of the first to fourth aspects from the wireless terminal according to the fourth or fifth aspect, and the agent program And a control unit for executing the agent program.
[0013]
According to a seventh aspect of the present invention, there is provided a buffer control means for storing data destined for a predetermined wireless terminal in a buffer, and receiving the signal indicating that the destination address of the wireless terminal has been changed. A path control means for changing a data transmission path to a later destination address, and a data transmitting means for transmitting data accumulated in the buffer to the changed destination address are provided.
[0014]
According to an eighth aspect of the present invention, in the seventh aspect of the invention, the data transmission unit changes the data stored in the buffer according to the data to the wireless terminal as the transmission destination. The transmission is performed to the previous destination address and the destination address after the data transmission path change.
[0015]
According to a ninth aspect of the present invention, in the invention according to the eighth aspect, if the data destined for the wireless terminal is real-time data, the data transmitting means transmits the real-time data after the buffer control process. First transmission means for transmitting to the destination address before the data transmission path change and the destination address after the data transmission path change, or if the data destined for the wireless terminal is non-real-time data, After the path control processing, the data transmission path is transmitted to the destination address after the data transmission path is changed.
[0016]
According to a tenth aspect of the present invention, a wireless terminal receives a radio signal from a first communication system connected via a network, and a second communication system around the first communication system. Receiving the radio signal, measuring the reception level or reception quality of the reception signal from the first and second communication systems, and measuring the reception level or reception quality of the reception signal from the first communication system. When the value is equal to or less than a predetermined threshold value, a connection is established via the network, and a management server that manages the address of the wireless terminal is provided at a branch point to the first and second communication systems in the network. 4. The agent according to claim 1, further comprising a step of requesting an address of a relay connected to the network, and receiving the address of the relay. Reads the agent program from the storage means for storing the program, and performs a process of transmitting to the repeater, the switching of the communication system by a process of switching the connection to the second communication system.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a network system to which a wireless terminal storing an agent program of the present invention and a repeater for executing the agent program will be described with reference to the drawings. FIG. 1 is a configuration diagram of the network system of the present embodiment. The network system according to the present embodiment includes a management server 100, a communication partner node 110, a switching point router 120, a wireless base station (hereinafter, referred to as a BS: BS: Base Station) 130, BS 150, BS 160, router 140, It comprises a service terminal 170.
The management server 100, the communication partner node 110, the switching point router 120, the BS / 130, the router 140, the BS / 150, and the BS / 160 are connected via a network.
[0018]
The management server 100 manages the position information and the like of the multi-service terminal 170 and has a function of specifying the switching point router 120 which is a branch point between the system A and the system B.
BS · 130 is a base station of wireless communication system A, and BS · 150 and BS · 160 are base stations of wireless communication system B.
Here, the wireless communication system A is a wireless communication area to which the multi-service terminal 170 belongs before handoff, and the wireless communication system B is a wireless communication area to which the multi-service terminal 170 belongs after handoff.
The BS 150 and the BS 160 are connected to each other using a router 140 which is a packet relay. Further, the wireless communication system A and the wireless communication system B are connected to each other using the switching point router 120.
[0019]
The switching point router 120 includes a CPU as a central processing unit, a ROM and a RAM as storage units, and is installed at a switching point between the wireless communication system A and the wireless communication system B. The storage unit stores CPU operation programs such as a reception program, a buffer control program, and a transmission program related to packet routing.
[0020]
Next, the configuration of the multi-service terminal 170 will be described with reference to FIG.
The multi-service terminal 170 includes a receiving unit such as a system A interface unit 200 and a system B interface unit 210, a processing unit such as a System Switch unit 220, an Internet protocol unit 230, and an application unit 240 (for example, a CPU, an MPU, a DSP, and the like). It is composed of a storage unit (not shown) such as a ROM and a RAM.
The system A interface unit 200 implements a physical layer and a data link layer of the OSI model in the wireless communication system A, and measures a reception level and a reception quality of a radio signal from the BS / 130 of the wireless communication system A using a wireless interface such as an antenna. I do.
Similarly to the system A interface unit 200, the system B interface unit 210 implements the physical layer and the data link layer of the OSI model in the wireless communication system B, and the BS / 150, BS From 160, the reception level and reception quality of the radio signal are measured.
[0021]
The system switch unit 220 includes a physical layer, a data link layer, and the like in the wireless communication system A and the wireless communication system B, and switches between the system A interface unit 200 and the system B interface unit 210 to be connected. Switch. For example, when the reception level or the reception quality of the reception signal from the system A falls below a predetermined threshold, the connection is switched to the BS 150 of the system B.
[0022]
The Internet protocol unit 230 implements a network layer such as TCP / IP and a transport layer, and performs protocol processing. That is, an Internet connection is established with the correspondent node 110 via the management server 100 that manages the address of the wireless terminal.
[0023]
The application unit 240 implements a session layer, a presentation layer, and an application layer, and performs display processing of data received from the wireless interface.
The storage unit is a semiconductor memory such as a ROM and a RAM, and stores an agent program and the like for executing a series of processes related to the buffer control and the like in the switching point router 120 described above.
The agent program is described in a programming language (such as Java (registered trademark)) that is not affected by the execution environment of the processing device, such as an OS, communicates with a buffer control program of the processing device, and sets a predetermined terminal as a destination. A buffer control process for storing data in a buffer; a route control process for changing a data transmission route to a changed destination address in response to a signal indicating that a destination address of the terminal has been changed; And a data transmission process of transmitting the changed data to the changed destination address.
[0024]
Next, the flow of handoff control by the wireless terminal (= multi-service terminal 170) and the switching point router 120 that executes the above-described agent program in the network system of the present embodiment will be described with reference to the drawings. FIG. 3 is a flowchart showing the flow of handoff control when the multi-service terminal 170 starts communication in system A, moves to system B, and continues communication.
[0025]
When the multi-service terminal 170 establishes an Internet connection from the system A via the communication partner node 110 and the management server 100 by the Internet protocol processing unit 230, the System Switch unit 220 sets the system A interface unit 200 and the system B interface unit 210 Start monitoring.
That is, first, the system A interface unit 200 and the system B interface unit 210 receive radio signals from the base stations (BS 130, BS 150, BS 160) of the respective systems, and determine the reception level and the reception quality. Monitor (step S1 in FIG. 3). When the system A interface unit 200 detects that the communication via the system A cannot be continued, that is, that the reception level or the reception quality of the reception signal from the BS 130 has become equal to or less than a predetermined threshold, the system switch unit 200 The detection result is output to 220.
[0026]
The System Switch unit 220 receives the detection result from the system A interface unit 200 and tries to detect another available system. That is, for example, it is determined whether the system B can be used based on the monitor information of the reception level or reception quality from the BS 150 and BS 160 from the system B interface unit 210. If it is determined that the system B is available (Yes in step S2), preparations for switching the connection from the currently communicating system A to the system B are started. On the other hand, if the reception level or the reception quality of the reception signal from the BS 130 exceeds a predetermined threshold (No in step S2), the process returns to step S1 with the system A currently communicating, and the connection is continued.
[0027]
In the case of Yes in step S2, the System Switch unit 220 transmits information (an identifier such as a network address) on the BS 150 to the management server 100 via the system A and an address request of the switching point router 120. The management server 100 acquires the address of the switching point router 120 based on the network addresses and the like of the BS 130 and the BS 150, and transmits this to the multi-service terminal 170.
[0028]
When receiving the address of the switching point router 120, the system A interface unit 200 of the multi-service terminal 170 outputs the address of the switching point router 120 to the System Switch unit 220. The system switch unit 220 reads the agent program from the storage unit and transmits the agent program to the switching point router 120 using the received address.
At this time, as shown in FIG. 4, the System Switch unit 220 includes, together with the agent program, an old IP address which is an IP address for transmitting a packet via the system A and a new IP address which is an IP address for transmitting a packet via the system B. Information such as the address and the type of data being communicated (for example, voice, image, moving image, etc. as real-time data, and file transfer as non-real-time data) is also transmitted.
[0029]
Upon receiving the agent program, the switching point router 120 executes it. That is, the processing unit of the switching point router 120 communicates with the buffer control program inside the switching point router 120 based on the agent program as shown in FIG.
FIG. 6 is a flowchart showing the flow of the buffer control processing and the packet transmission path control processing in the switching point router 120. The processing unit of the switching point router 120 outputs an interrupt control instruction regarding handoff to the buffer control program being executed, and when the buffer control program accepts the instruction, the buffer control, the path control, and the data The transmission control is executed ("Yes" in step S10 of FIG. 6).
[0030]
If the IP address written in the IP header of the received data is the old IP address of the multi-service terminal 170 ("old route data" in step S11), the processing unit of the switching point router 120 determines that the old route data is the old route data. As a catch. Then, the processing unit of the switching point router 120 creates the new route data by copying the old route data into the data portion of the new route data and writing the new IP address in the IP header, and writes the new route data into the buffer (step S12). .
When the process of writing to the buffer is completed, the processing unit of the switching point router 120 transmits the old route data to the multi-service terminal 170 via the system A (Step S13).
When the received data is the old route data, the processing unit of the switching point router 120 repeatedly executes the processing of steps S11 to S13.
[0031]
During the repetition of this step, the multi-service terminal 170 moves to the system B via the system A or the system B to the management server 100 in order to make communication difficult in the system A and switch to the system B. Notify.
In response to this notification, the management server 100 changes the data at the destination via the system A to the data via the system B (encapsulated with a header including the destination via the system B) as shown in FIG. .
[0032]
In this way, when the multi-service terminal 170 switches from the system A to the system B, and new route data including a new IP address arrives from the management server 100, the switching point router 120 causes the multi-service terminal 170 to switch. Judge as completed. If the IP address written in the IP header of the received data is the new IP address of the multi-service terminal 170 ("new route data" in step S11), the processing unit of the switching point router 120 firstly converts this into the new route data. Capture as.
Then, the processing unit of the switching point router 120 writes this in the buffer (step S14). When the process of writing to the buffer is completed, the processing unit of the switching point router 120 transmits the new route data to the multi-service terminal 170 via the system B (Step S15).
The processing unit of the new route data switching point router 120 for which the received data is the new route data switching point router 120 repeatedly executes the processing of steps S11, S14, and S15.
[0033]
As described above, the switching point router 120 filters the packet, checks whether or not the data should be subjected to the buffer control and the route control processing, and notifies the multi-service terminal 170 of the old route data and the new route data. Both of the data are transmitted according to the destination address. Otherwise, a routing process is performed according to the destination address of the received data.
[0034]
FIG. 8 is a flowchart showing a flow in which the multi-service terminal 170 receives the old route data and the new route data, discards duplicate packets among these data, and reconstructs the data.
After transmitting the agent program, the multi-service terminal 170 receives the data via the system A before switching the communication system to the system B, and switches to the system B and switches to the system B Receive data. Then, the System Switch 220 unit performs a conveyor check by comparing each packet whether the received old route data and new route data match (step S20). If there is an overlapped packet among the received old route data and new route data, this duplicate data is discarded (step S21), and the received data is reconstructed. Output (Step S22).
[0035]
As described above, even when switching from the system A to the system B, the multi-service terminal 170 has an effect that it can smoothly receive data from the correspondent node 110 while preventing loss of communication data due to packet loss. can get.
[0036]
Next, when the processing unit of the switching point router 120 executes the agent program and performs buffer control, route control, and data transmission control, the data type indicated by the agent program to the buffer control program is different from that of the real-time application. The operation of the switching point router 120 and the multi-service terminal 170 for the case of a real-time application will be described.
[0037]
First, a case where the data type is a real-time application will be described with reference to FIGS. FIG. 9 is an explanatory diagram showing a state of the path control processing of the switching point router 120 when the data type indicated by the agent program to the buffer control program is a real-time application. FIG. 10 is an explanatory diagram showing a state of the data comparison processing of the multi-service terminal 170 in this case.
[0038]
Upon receiving the old route data via the system A, the switching point router 120 transmits this to the multi-service terminal 170. Thereafter, when the agent program is received, it is stored in the memory, and the processing unit of the switching point router 120 executes the agent program.
When the IP address written in the IP header of the received data is the old IP address of the multi-service terminal 170, the processing unit of the switching point router 120 captures this. Then, the old route data is copied to the data portion of the new route data, and the new IP address is written in the IP header, thereby creating new route data and writing it into the buffer.
When the processing of writing to the buffer is completed, the processing unit of the switching point router 120 transmits the old route data to the multi-service terminal 170 via the system A. In addition, the switching point router 120 transmits the new route data stored in the buffer to the multi-service terminal 170 via the system B with a delay from the transmission of the old route data in consideration of the time required for the handoff.
[0039]
The multi-service terminal 170 completes the handoff from the system A to the system B while repeating this flow. Upon completion of the handoff, the management server 100 changes the care-of address added to the data received from the correspondent node from the old IP address to the new IP address, and transmits the changed address to the switching point router 120. Upon receiving the new route data including the new IP address, the switching point router 120 determines that the multi-service terminal 170 has completed the handoff, and writes this in a buffer. When the processing of writing to the buffer is completed, the processing unit of the switching point router 120 transmits the data converted to the new path and the new path data to the multi-service terminal 170 via the system B in the order of accumulation in the buffer.
[0040]
On the other hand, the multi-service terminal 170 receives the data via the system A before the handoff, switches the communication system from the system A to the system B by the handoff, and receives the data via the system B. At this time, the multi-service terminal 170 receives the data received via the system A and the data stored in the buffer at the temporary switching point router 120 and transmitted to the system B at a later time after being overlapped. .
[0041]
Then, the System Switch 220 writes the data received from the system A interface unit and the data received from the system B interface unit into respective buffers, performs a compare check of both data, and discards duplicated data. That is, the data arriving from the system A is output to the application unit 240 first, and the data arriving from the system B is discarded of the duplicated data. From the continuation, it outputs to the application part 240.
Therefore, at the time of handoff, handoff between systems can be performed while preventing data loss due to packet loss.
[0042]
Next, a non-real-time application will be described with reference to FIGS. FIG. 11 is an explanatory diagram showing a state of the path control processing of the switching point router 120 when the data type indicated by the agent program to the buffer control program is a real-time application. FIG. 12 is an explanatory diagram showing a state of data processing of the multi-service terminal 170 in this case.
Upon receiving the old route data via the system A, the switching point router 120 transmits this to the multi-service terminal 170. Thereafter, when the agent program is received, it is stored in the memory, and the processing unit of the switching point router 120 executes the agent program.
When the IP address written in the IP header of the received data is the old IP address of the multi-service terminal 170, the processing unit of the switching point router 120 captures this. Then, the old route data is copied to the data portion of the new route data, and the new IP address is written in the IP header, thereby creating new route data and writing it into the buffer. After the writing to the buffer is completed, the processing unit of the switching point router 120 discards the old route data of the copy source.
[0043]
The multi-service terminal 170 completes the handoff from the system A to the system B while repeating this flow. Upon completion of the handoff, the management server 100 changes the care-of address added to the data received from the communication partner node from the old IP address to the new IP address, and transmits the changed address to the switching point router 120. Upon receiving the new route data including the new IP address, the switching point router 120 determines that the multi-service terminal 170 has completed the handoff, and writes this in a buffer. When the processing of writing to the buffer is completed, the processing unit of the switching point router 120 transmits the data converted to the new path and the new path data to the multi-service terminal 170 via the system B in the order of accumulation in the buffer.
[0044]
At this time, when the switching point router 120 starts executing the agent program, data transmission via the system A is stopped, so that data via the system A does not reach the multi-service terminal 170. Then, when the multi-service terminal 170 performs a handoff from the system A to the system B, after the switching point router 120 buffers the data, all the data that has stopped transmitting data via the system A can be received via the system B.
[0045]
When the multi-service terminal 170 receives these data, the System Switch unit 220 writes the received data of the system A interface unit and the received data of the system B interface unit into respective buffers, and performs a system check without performing a check. The data arrived from B is passed to the application unit 240.
Therefore, even if the multi-service terminal 170 temporarily stops data communication to the old system A before moving during the handoff process, data loss due to packet loss with the correspondent node 100 can be prevented, Handoff is possible. This is based on the fact that there is no problem even if a slight data delay occurs in a non-real-time application, and the multi-service terminal 170 does not need to perform a con- ference check. An effect is obtained in that handoff can be performed without applying a processing load due to the check.
[0046]
As described above, regardless of whether the communicating application is a real-time application or a non-real-time application, as shown in FIG. 13, the buffer control method of the switch point router 120 and the data comparison of the multi-service terminal 170 are performed. By appropriately changing the processing, a handoff according to the application can be realized.
[0047]
In the present embodiment, a case has been described where the multi-service terminal 170 explicitly notifies the management server 100 of the new IP address, and the correspondent node 110 transmits the new route data. The communication partner node 110 may transmit the new route data by explicitly notifying the communication partner node 110 of the new IP address instead of the management server 100, for example.
Further, in the present embodiment, the System Switch unit 220 obtains the address of the switching point router 120 by requesting the address of the switching point router 120 from the management server 100. In the case described above, the management server 100 may be simulated as the switching point router 120 and an agent program may be transmitted to the management server 100 in order to suppress the packet loss in the delay time.
[0048]
In the present embodiment, the processing unit of the switching point router 120 creates the new route data by copying the old route data into the data portion of the new route data and writing the new IP address in the IP header. The present invention is not limited to this, and after encapsulating the old route data copied with the new IP address, storage in a buffer, data transmission, and the like may be performed.
Further, as shown in FIG. 1, the network system according to the present embodiment has been described as including a plurality of systems including a wireless communication system A and a wireless communication system B. However, the present invention is not limited to this. In a network system composed of a plurality of communication systems, the present invention can be applied to any of them.
[0049]
The above-described wireless terminal, repeater, and management server have a computer system therein. The series of processes related to the above-described handoff control are stored in a computer-readable recording medium in the form of a program, and the above-described process is performed when the computer reads and executes the program. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to a computer via a communication line, and the computer that has received the distribution may execute the program.
[0050]
【The invention's effect】
As described above, the present invention provides a process in which a wireless terminal receives a radio signal from a first communication system connected via a network, and a process of receiving a radio signal from a second communication system around the first communication system. Receiving the radio signal, measuring the reception level or reception quality of the reception signal from the first and second communication systems, and determining whether the reception level or reception quality of the reception signal from the first communication system is a predetermined value. If the value is equal to or less than the threshold value, the connection is made via the network, and the relay connecting to the network at the branch point to the first and second communication systems in the network is transmitted to the management server that manages the address of the wireless terminal. Requesting the address of the relay device, a buffer control process for receiving the address of the relay device and storing data destined for the wireless terminal in a buffer in a buffer. In response to a signal indicating that the destination address of the wireless terminal has been changed, a route control process of changing the data transmission route to the changed destination address, and changing the data stored in the buffer to the changed destination address The agent program is read from a storage unit storing an agent program for causing a computer to execute a data transmission process to be transmitted to the computer, and the agent program is transmitted to the repeater and the connection is switched to the second communication system. Since the switching is performed, it is possible to obtain an effect of preventing data loss even when the communication system or the communication network is switched.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an overall configuration of a network system according to an embodiment.
FIG. 2 is a block diagram showing a configuration of a multi-service terminal 170.
FIG. 3 is a flowchart showing a flow of handoff control when the multiservice terminal 170 starts communication in system A, moves to system B, and continues communication.
FIG. 4 is an explanatory diagram showing a state in which an agent program is transmitted from the multi-service terminal 170 to the switching point router 120.
FIG. 5 is an explanatory diagram showing how an agent program communicates with a buffer control program of a switching point router 120.
FIG. 6 is a flowchart showing a flow of a buffer control process in the switching point router 120;
FIG. 7 is a data configuration diagram illustrating data in which the management server 100 encapsulates data via the system A with a header including a destination via the system B.
FIG. 8 is a flowchart showing a flow of a comparison check of received data in the multi-service terminal 170.
FIG. 9 is an explanatory diagram showing a state of a path control process of the switching point router 120 when the data type indicated by the agent program to the buffer control program is a real-time application.
FIG. 10 is an explanatory diagram showing a state of a data comparison process of the multi-service terminal 170 in the case of FIG.
FIG. 11 is an explanatory diagram showing a state of a path control process of the switching point router 120 when the data type indicated by the agent program to the buffer control program is a non-real-time application.
FIG. 12 is an explanatory diagram showing a state of a data comparison process of the multi-service terminal 170 in the case of FIG.
FIG. 13 is an explanatory diagram showing a comparison of received data in the case of a real-time application, a non-real-time application, and the case of a conventional technique.
FIG. 14 is a configuration diagram showing an overall configuration of a conventional network system based on Mobile IP.
[Explanation of symbols]
100 ... management server
110 ... communication partner node
120 ... Switch point router
130, 150, 160 ... BS
140 ... Router
170 ... Multi-service terminal

Claims (10)

Buffer control processing for storing data having a predetermined terminal as a destination in a buffer;
A route control process of receiving a signal indicating that the destination address of the terminal has been changed, and changing a data transmission route to the changed destination address;
An agent program for causing a computer to execute a data transmission process of transmitting data stored in the buffer to the changed destination address. In the data transmission process, data stored in the buffer is transmitted to a destination address before the data transmission path change and a destination address after the data transmission path change in accordance with data having the terminal as a destination. The agent program according to claim 1, wherein the agent program is a process. In the data transmission process, if the data destined for the terminal is real-time data, after the buffer control process, the real-time data is transmitted to the destination address before the data transmission path change and to the transmission after the data transmission path change. A process of transmitting to the destination address, or a process of transmitting to the destination address after the data transmission route change after the route control process if the data destined for the terminal is non-real-time data. The agent program according to claim 1, wherein Receiving means for receiving a radio signal from a first communication system connected via a network;
Second receiving means for receiving a radio signal of a second communication system around the first communication system;
Measuring means for measuring a reception level or reception quality of a signal received from the first and second communication systems;
When the reception level or the reception quality of the reception signal from the first communication system is equal to or less than a predetermined threshold, the management server is connected via the network and manages the address of the wireless terminal. Requesting means for requesting an address of a relay connected to the network at a branch point to the first and second communication systems in the network;
Transmitting means for receiving the address of the relay device, reading the agent program from a storage device for storing the agent program according to any one of claims 1 to 3, and transmitting the agent program to the relay device;
Connection switching means for switching a connection to the second communication system;
A wireless terminal comprising: The first data obtained by demodulating a radio signal from the first communication system is compared with the second data obtained by demodulating a radio signal from the second communication system, and the first data and the second data are compared. 5. The wireless terminal according to claim 4, further comprising a data comparison unit that discards one of the first data and the second data when the data overlaps. Receiving means for receiving the agent program according to any one of claims 1 to 4 from the wireless terminal according to claim 4 or claim 5;
Writing means for writing the agent program into storage means;
Control means for executing the agent program. Buffer control means for storing data having a predetermined wireless terminal as a transmission destination in a buffer,
Path control means for receiving a signal indicating that the destination address of the wireless terminal has been changed, and changing a data transmission path to the changed destination address;
And a data transmitting means for transmitting the data stored in the buffer to the changed destination address. The data transmission means transmits the data stored in the buffer to a destination address before the data transmission path change and a destination address after the data transmission path change in accordance with data to the destination of the wireless terminal. The repeater according to claim 7, wherein: The data transmission means, if the data to which the wireless terminal is the destination is real-time data, after the buffer control process, the real-time data is transmitted to the destination address before the data transmission path change and after the data transmission path change First transmission means for transmitting to the transmission destination address, or, if the data destined for the wireless terminal as the transmission destination is non-real-time data, transmission to the transmission destination address after the data transmission path change after the path control processing 9. The repeater according to claim 8, comprising a second transmission unit. The wireless terminal
Receiving a radio signal from a first communication system connected via a network;
Receiving a radio signal of a second communication system around the first communication system;
Measuring a reception level or reception quality of a reception signal from the first and second communication systems;
When the reception level or the reception quality of the reception signal from the first communication system is equal to or less than a predetermined threshold, the management server is connected via the network and manages the address of the wireless terminal. Requesting the address of a repeater connected to the network at a branch point to the first and second communication systems in the network;
Receiving the address of the repeater, reading the agent program from storage means for storing the agent program according to any one of claims 1 to 3, and transmitting the agent program to the repeater;
A handoff control method, wherein a communication system is switched by a process of switching a connection to the second communication system.

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