JP4679415B2 - Communication system and communication method - Google Patents

Description

  The present invention is used in a mobile network system by a communication terminal having a plurality of wireless communication means, a communication program for performing communication via a plurality of networks, a communication system for providing a conversational or streaming application service to a user, and communication Regarding the method.

  With recent advances in wireless technology, connection to the Internet using various wireless communication methods has become widespread, and mobile communication environments in mobile environments have been provided by taking advantage of wireless. In addition, as mobile terminals become more sophisticated, a single terminal device can be connected to multiple networks (for example, a wireless local area network (LAN), a wired LAN, a mobile phone, a PHS (Personal Handy-phone System, etc.). As a result, it is possible to connect to a plurality of types of networks with a single terminal device, and it is possible to perform communication by selecting an optimum communication environment each time it is used. It is coming.

  In addition, with the advent of technologies that enable continuous wireless communication between different networks (Mobile IP: Mobile Internet Protocol, etc.), the optimal communication environment is selected each time it is used and communication is interrupted. It is becoming possible to receive services without any change (for example, see Non-Patent Document 1 or Non-Patent Document 2). In addition, a technique has been proposed in which the quality of received data is changed in accordance with a change in communication state accompanying switching of a network that performs wireless communication (see, for example, Patent Document 1).

On the other hand, a method is known in which a probe packet is transmitted from a terminal connected to the network to the network, delay information of the probe packet received at the receiving terminal is collected, and a bandwidth in the network is calculated (for example, Non-Patent Document 3). reference). There is a method of measuring the bottleneck physical bandwidth as a method using the bandwidth estimation method.
JP 2004-272563 A RFC2002, IP Mobility Support RFC3775, Mobility Support in IPv6 Constantinos Dovrolis and Parameswaran Ramanathan David Moore, Packet Dissipation techniques and a capacity estimation methodology

  However, in the technique disclosed in Patent Document 1, the communication state (transmission path state between communication terminals) when performing network switching control is dynamically acquired for all communicable network interfaces. It is not considered to do. For this reason, depending on the actual communication state, there may be a case where the network needs to be switched again.

  In the technique disclosed in Non-Patent Document 3, it is possible to estimate an end-to-end transmission path state between communication terminals, but a large amount of probe packets are transmitted and the result is statistically calculated. Processing, and it takes a lot of time to estimate the transmission path state. In general, it is known that it takes a lot of time to estimate the end-to-end transmission path state, and at the start of communication, the end-to-end transmission path state is set for each transmission path. When the transmission path is selected after estimation, it is expected that a great time lag will occur between the time when the user makes a communication request and the time when communication is actually started.

In addition, since a large number of probe packets are transmitted for measurement, whether the probe packets are due to the increasing DoS attack (Denial of Service attack) or the measurement of the original transmission path. No means for confirmation is provided.
The present invention provides a communication system and a communication method for efficiently solving the various problems described above.

The communication system according to the present invention is a communication system in which a communication terminal including a plurality of network interfaces connectable to a plurality of transmission paths uses the plurality of transmission paths. At least one terminal of the communication terminal, obtained in the mobile terminal under the control of the home agent detects the communicable network interface among the plurality of network interfaces, network interface information on predetermined attribute of the plurality of network interfaces from the network The network interface management unit to be registered in the network interface information table, the communicable network interface and the communicable network interface of the communication partner are notified to each other, and a transmission path list existing between the communication partners is created. and, a transmission line management unit for registering the transmission path information table, obtained using a mobile IP control message information on the status of the transmission path corresponding to the transmission line list, the transmission as a transmission path information Determining a channel state management unit for writing the information table, the priority criteria set for each application program for data communication priority of the transmission path, transfer based on one of the network interface information and the transmission path information sending passage A transmission path selection unit for determining the data, and performing data communication via the determined transmission path. Communication terminals that communicate with each other include fixed terminals.

The acquisition of information about the state of the transmission path, may be acquired transfer sending passage information stepwise. In this case, the transmission path is determined for each transmission path state, and when the determined transmission path is different from the transmission path in communication, the transmission path is switched to the newly determined transmission path. However, even if the determined transmission path is different from the transmission path in communication, there is a case where the newly determined transmission path is not switched. The network interface information includes the communication status detected in a layer lower than the transport layer. For example, the network interface transmission speed, the radio wave strength of the wireless communication, the link state of the network interface, etc., which are different in uplink / downlink are used. It is done.

  The transmission path information includes a bottleneck physical bandwidth, usable bandwidth, RTT, communication cost, and the like between a network to which a plurality of network interfaces are connected and a communication partner. In measuring the bottleneck physical bandwidth, a mobile IP control message is used as a part of a probe packet, and the validity of the packet is confirmed using authentication information of the control message. In addition to the measurement of the bottleneck physical bandwidth, the mobile IP control message is similarly used as a part of the probe packet for those using the probe packet for other transmission path information.

In determining the priority of the transmission path, if the transmission path characteristics of the uplink / downlink is different asymmetric communication network may select a transmission path different from the uplink / downlink by the priority criteria. When the required bandwidth is used as a priority criterion, a plurality of required bandwidths are set for each application program.

  There are some cases where it takes time to acquire the transmission path information. For such cases, the result of measurement using the home registration packet, which is a mobile IP control message, as part of the probe packet (bottleneck physical bandwidth, available bandwidth). Width, RTT, communication cost, etc.) and the network interface information described above, and the priority of the transmission path is determined based on the priority of the network interface preset in the terminal by the user or the like. The re-association request message, which is a mobile IP control message, is also used as a part of the probe packet, so that the state of the transmission path during communication (bottleneck physical bandwidth, usable bandwidth, RTT, communication cost) Etc.) and monitor the communication status.

  The data type of the data communication refers to the quality information set for each application program and the transmission path information related to the determined transmission path, and determines the content quality from the information. Also, after the data communication, when the status of the network interface not in data communication or the transmission path status of the transmission path being used changes, the priority of the transmission path is judged again and the transmission path is switched to the highest priority transmission path. .

  According to the present invention, in a network system including a mobile terminal having a plurality of network interfaces in a communication environment that changes every moment as a user moves, when data communication is performed by an application using communication such as video and audio. The transmission path can be selected according to the priority standard set for each application or the user's preference. In addition, it is possible to maintain the communication quality even when moving to a different network by switching the wireless communication means, and according to the location where the communication terminal exists by selecting the content of quality matching the network information Quality service can be provided.

  In addition, even when transmission line information cannot be acquired immediately at the start of data communication, a quality service tailored to the transmission line selected based on information set in the terminal in advance or information acquired so far It becomes possible to provide. Furthermore, even during data communication, due to changes in the communication status of the transmission path, the transmission path status is acquired again, or the priority criteria or user preferences set for each application based on previously acquired information By selecting the transmission path again according to the above, even in a communication environment that changes every moment, it becomes possible to provide a service with quality optimum for the communication environment where the communication terminal exists. Furthermore, since the authentication is performed on the packet used for acquiring the transmission path state, the validity of the probe packet can be confirmed.

Prior to the description of the present invention, first, Mobile IPv6 (IETF: Internet Engineering Task Force) RFC3775 will be described.
FIG. 1 is a schematic diagram for explaining Mobile IPv6. In Mobile IPv6, a home network HN is defined as a network to which the mobile terminal MN is originally connected. An address assigned to the mobile terminal MN in the home network HN is called a home address (Haddr), and the home address is always used for communication with other terminals. In the home network HN, a so-called home agent HA that manages the mobile terminal MN is arranged, and the home agent HA grasps the location of the mobile terminal MN away from the home network HN and transfers a packet as necessary.

  Next, when the mobile terminal MN moves from the home network HN to the destination network FN, the mobile terminal MN obtains a new address called a care-of address (CoA) in the destination network FN and sends a care-of address to the home agent HA. Perform home registration (HR). In home registration, encryption is performed and a mechanism for ensuring security is provided. When communicating with another terminal, the home address is used, and a packet transmitted from the mobile terminal MN is once sent to the home network HN via a tunnel route created with the home agent HA, and further, By transferring the agent HA to the communication partner terminal CN, communication can be continued even if the network segment is moved.

  Further, in the above method, since a packet to be transmitted / received to / from the mobile terminal MN always passes through the home agent HA, there is a possibility that the packet follows a redundant route. Mobile IPv6 provides a mechanism for improving the redundant route by performing route optimization processing. First, the mobile terminal MN sends an association update message (BU) to the communication partner terminal CN in a message similar to that for home registration HR, so that the mobile terminal MN directly communicates with the communication partner instead of passing through the tunnel of the home agent HA. A communication path is secured. As for the processing of the association update message BU, a mechanism for protecting a message using a shared key generation method called round-trip route confirmation (RR) is provided as in the home registration HR. The mechanism is described below.

  The mobile terminal MN transmits a home test request message (HoTI) and a care-of test request message (CoTI) to the correspondent terminal CN before sending the association update message BU. The home test request message HoTI is sent directly from the destination network FN via the home agent HA. The counterpart terminal CN that has received the test request returns a home test response (HoT) and a care-of test response (CoT).

Similarly, in these messages, the home test response HoT is sent back to the destination network FN directly via the home agent HA. The correspondent terminal CN stores information called a token in the response message, and the mobile terminal MN generates a key from the two received tokens, and signs the association update message BU using the key. As described above, since the encryption process is performed between the home agent HA and the mobile terminal MN, the eavesdropping of the token is prevented in that section.
By performing the above processing, data communication is continuously performed even if the network segment is moved, including protection of a message for performing the moving processing.

Next, the overall configuration of a wireless network to which the communication system according to the present invention is applied and its accessible area will be described.
FIG. 2 is a conceptual diagram of an accessible area corresponding to a wireless base station and a wireless access point. In FIG. 2, networks 1 to 3 are networks in units of network segments such as LAN and WAN. The mobile base station 1 is connected to the network 1, the wireless AP 2 is connected to the network 2, and the PHS base station 3 is connected to the network 3. Yes. The network for each network segment is an IP-based network and is connected to the core network.

  For each accessible area, the mobile base station 1 corresponds to the mobile area 1, the wireless AP 2 corresponds to the wireless LAN area 2, and the PHS base station 3 corresponds to the PHS area 3. The communication terminal 1 can communicate with each wireless communication method. The communication terminal 1 includes a network interface card (hereinafter referred to as NIC) that can be connected to the mobile base station 1, the wireless AP 2, and the PHS base station 3, and in the wireless LAN area 2, the mobile base station 1, the wireless AP 2, and the PHS base station 3. Can be connected to the networks 1 through 3 respectively.

  Similarly, in the mobile / PHS area 4, it can be connected to the networks 1 and 3 via the mobile base station 1 and the PHS base station 3 respectively. In the area excluding the mobile / PHS area 4 from the mobile area 1 as described above, Only the network 1 can be connected via the mobile base station 1. In the area excluding the mobile phone / PHS area 4 from the PHS area 3, it is possible to connect only to the network 3 via the PHS base station 3. For example, when the communication terminal 1 moves and moves from the state connected to the network 2 via the wireless AP 2 in the wireless LAN area 2 to move to the mobile / PHS area 4 and connects to the network 3 via the PHS base station 3 Since the movement is between network segments, the IP control unit described later can continue communication by supporting, for example, Mobile IPv6 (RFC3775).

  When it is selected that the network 1 is more suitable according to the application used in the communication terminal 1, it is possible to connect to the network 1 via the mobile base station 1. Similarly, when moving from the state connected to the network 3 via the PHS base station 3 in the mobile / PHS area 4 to the mobile area 1 that can be connected only to the mobile base station 1, the mobile base station in the mobile / PHS area 4 Even when moving from the state of being connected to the network 1 via 1 to the PHS area 3 that can be connected only to the PHS base station 3, communication can be continued by the above-described technology such as mobile IP.

  Further, in the wireless LAN area 2, since it can be connected to the networks 1 to 3 via the mobile base station 1, the wireless AP 2, and the PHS base station 3, a suitable network is selected depending on the application being used. Here, although mobile, PHS, and wireless LAN are cited as wireless communication systems, Bluetooth (Bluetooth), which is a short-range communication, IMT (International Mobile Telecommunication) -2000, which is a broadband mobile communication system, and WiMAX (Worldwide) As long as an IP-based network such as Interoperability for Microwave Access IEEE 802.16e) can be provided, any wireless communication method may be used.

  In addition, as a form of communication, 1) In the case where the transmission side is a communication terminal (mobile terminal) and the reception side is a communication terminal (fixed terminal) that is fixedly connected, 2) The communication terminal in which the transmission side is fixedly connected (fixed terminal) In the case where the receiving side is a communication terminal (mobile terminal) that is a fixed terminal), 3) both the transmission side and the reception side of communication may be mobile communication terminals (mobile terminals). In these cases, by applying the present invention to the communication terminal on the transmission side and the reception side, it is possible to control the application according to the switching of the transmission path.

  Next, an embodiment according to the present invention will be described. FIGS. 3A and 3B are functional block diagrams illustrating configuration examples of the communication terminal and the home agent used in the present invention, respectively. In the figure, 10 is a communication terminal, 11 is an application unit, 12 is a user setting unit, 13 is a content / communication control unit, 14 is an application priority reference table, 15 is a quality information table, 16 is a transmission path control unit, and 17 is a transmission. A path management unit, 18 a transmission path selection unit, 19 an IP control unit, 20 a transmission path state management unit, 21 a transmission path quality table, 22 a transmission path information table, 23 a network interface information table, and 24 a network interface The management unit 25 is a network interface card (NIC), and 28 is a home agent terminal.

  As shown in FIG. 3A, the communication terminal 10 used as a mobile terminal in the communication system of the present invention includes an application unit 11 that performs transmission / reception and processing of actual communication data, and a network interface card 25 (hereinafter referred to as NIC). And a transmission line control unit 16 that performs state management and control of the transmission line. The communication terminal 10 may be a portable telephone terminal, a PDA (Personal Digital Assistance) or a personal computer that can be connected to a wireless network, and any terminal provided with a plurality of wireless communication means.

  The application unit 11 is included in the application program, receives a service start request from the user, and transmits the application priority standard to the transmission path control unit 16 based on the service definition information and the application priority standard table 14. The transmission path control unit 16 is included in the application program or used by the application program. The transmission line control unit 16 matches the network interface information obtained by the network interface management unit 24 and the transmission line information obtained by the transmission line state management unit 20 based on the application priority standard from the application unit 11. Thus, the transmission path selection unit 18 determines the transmission path.

  Further, the transmission path selection unit 18 returns information regarding the selected transmission path to the application unit 11. In response to the information, the content / communication control unit 13 refers to the quality information table 15 to determine the content, and the content / communication control unit 13 transmits / receives data to provide the service. Note that each unit of the communication terminal 10 may be realized by any of hardware, software, and a combination thereof.

  Next, each part of the communication terminal 10 described above will be described in more detail. The network interface management unit 24 manages the NIC 25 provided in the communication terminal 10 and monitors the state. The network interface management unit 24 registers information (for example, transmission rate (standard value), fee, IP address, communication card standard, MTU (Max Transfer Unit), etc.) acquired for the NIC 25 in the network interface information table 23.

  The network interface information table 23 is constantly updated by monitoring the state when a NIC is newly added to the communication terminal 10, when it is removed, and when it is usable / unusable. An example of the network interface information table 23 is shown in FIG. The network interface management unit 24 acquires the items described in FIG. 8 from the device information of the NIC 25 every time the state of the NIC 25 changes.

  The transmission path state management unit 20 detects a transmission path (path) that can be used with the communication partner based on the NIC information acquired by the network interface management unit 24. Further, the transmission path state (for example, bottleneck physical bandwidth, usable bandwidth, RTT delay difference, packet loss rate, etc.) is acquired for each detected transmission path and registered in the transmission path information table 22. When the NIC information is updated, NIC information registration, path detection, and transmission path information are acquired each time. However, in the case of the above processing, transmission path information may be newly acquired only for the updated path.

  The transmission path management unit 17 uses the transmission path information acquired by the transmission path state management unit 20 and the application priority standard (for example, request bandwidth, request delay, fee, priority transmission path, etc.) received from the application unit 11. Select the optimal transmission path for As a selection result, one transmission path optimal for the application may be selected, or the priority of the transmission path may be obtained and the communication partner may select it. After selecting the transmission path, the transmission path status (bandwidth, delay, packet loss rate, fee, etc.) of the selected transmission path is returned to the application unit 11, and transmission of the transmission path having the second highest priority at the same time The path state (bandwidth, delay, packet loss rate, fee, etc.) is registered in the transmission path quality table 21.

  The content / communication control unit 13 refers to the quality information table 15 based on the transmission path state answered by the transmission path management unit 17 and selects a content type that can be transmitted and received. The content type here refers to, for example, video / audio bit rate, codec type, angle of view, frame rate, and the like in video streaming, and codec type in VoIP (Voice over Internet Protocol).

The content / communication control unit 13 starts providing the service after negotiating with the communication partner so as to transmit / receive data of the content type selected above. It also exchanges application information (such as standby port number and usable codec type) with the communication partner. By transmitting and receiving the information, the service quality that can be provided by the application program can be shared.
The user setting unit 12 is an input / output unit that allows the user to set the communication terminal 10 and set and operate the application priority reference table 14. The user setting unit 12 includes a screen, buttons, a mouse, and the like, and the function of the application unit 11 is also controlled by executing a command specified by the user.

  The IP control unit 19 sets address information and the like necessary for transmitting data to the IP network (see FIGS. 1 and 2), and transmits / receives the created data to / from the actual network via the NIC 25. In addition, transmission / reception of a control message for movement control by mobile IP and measurement of a transmission path state in cooperation with the transmission path state management unit 20 are performed. The communication terminal 10 is connected to a network and can move while maintaining the connection with the network.

  The home agent terminal 28 includes a transmission path management unit 17 and a network interface card (NIC) 25 as shown in FIG. The transmission path management unit 17 manages the movement of the communication terminal 10 and performs packet transfer and the like, and measures the transmission path state between the mobile terminal and the home agent HA in cooperation with the IP control unit 19. It is comprised with the transmission-line state management part 20. FIG.

  FIG. 4 is a diagram for explaining an example of an operation sequence at the start of communication of the communication terminal 10 of FIG. 3A described above, and FIG. 5 is a diagram for explaining an example of an operation sequence when the communication state of the network interface changes. FIG. 6 is a diagram for explaining an example of an operation sequence when the transmission line state (transfer quality) of the transmission line in communication changes, and FIG. 7 shows another example of the operation sequence at the start of communication (when using simple measurement). FIG.

  4 to 7, the own terminal 26 is a communication terminal on the transmission side that starts communication, and the communication partner terminal 27 is a communication terminal on the reception side with respect to the communication terminal on the transmission side. Each communication terminal can use the communication terminal 10 having a plurality of network interfaces connectable to the above-described IP network. Also, data communication for communication such as video and audio is performed via the wireless access point and the wireless base station described in FIG.

  The connection form may be one-to-one or a communication form such as a multipoint conference with a plurality of people. The data communication may be one-way communication between the server and the client, or two-way communication such as a telephone. 5 and 6, the own terminal 26 is a communication terminal that detects a change in the communication state of each NIC, or a communication terminal that detects a change in the transmission path state of a transmission path that is in communication. The terminal 27 becomes a communication terminal with which the terminal 26 is communicating. In this case, the terminal 26 and the communication partner terminal 27 may be either a transmitting terminal or a receiving terminal. In addition, each communication terminal may be a communication terminal in which one has only one NIC.

Example 1
First, referring to FIG. 4, the sequence operation of the own terminal 26 and the communication partner terminal 27 at the start of communication and the state of each part when the communication terminal performs data communication by an application using communication such as video and audio will be described. To do. In the description, the reference numerals are used with reference to FIGS.

  In the communication terminal 10 described above, when the communication terminal is activated, the network interface management unit 24 obtains information related to the attributes of the plurality of NICs 25 (for example, communication card name, transmission speed, radio wave intensity, link status, modulation method, etc.). To do. Network interfaces that can communicate simultaneously are detected and registered in the network interface information table 23 (S401). Examples of the method for detecting the network interface include determination based on comparison between radio wave intensity and a threshold value, link status, and the like.

  After the communication terminal 10 is activated, the network interface management unit 24 constantly monitors changes in the status of addition / deletion of the NIC 25 and communication enable / disable and updates the items in the network interface information table 23 one by one. Writing is performed each time, and only the changed item is notified to the transmission path management unit 17. At this time, all items may be notified. FIG. 8 shows an example of items registered in the network interface information table 23 and values thereof.

  As a detection method of the NIC 25, determination based on comparison between radio wave intensity and a threshold, a link state, and the like can be given. As an example of detection by radio wave intensity, when the threshold is set to Level 3 and the radio wave intensity is Level 3 or higher, the flag is “1” (the network interface is usable as the flag “1”; Is written in the position of the link status flag in the network interface information table.

  On the other hand, if the radio field intensity is less than Level 3, the link state flag “0” is written in the same position as described above. The threshold value may be determined by an application, may be built in the communication terminal 10 in advance, or may be set by the user via the user setting unit 12. According to the threshold value of this example, the network interface management unit 24 does not change the link state flag even if it detects that the radio field intensity has changed from Level 1 to Level 2.

  As an example of detection based on the link state, a NIC such as a mobile phone or a PHS cannot establish a connection to the IP network unless dial-up connection is performed. Therefore, when the dial-up connection is established, an “ON” flag is written in the link state position of the network interface information table, and when the dial-up connection is not established, an “OFF” flag is written.

  Upon receiving a communication start request from the user setting unit 12, the application unit 11 notifies the information necessary for performing data communication with the application between the own terminal 26 and the communication partner terminal 27 (S402). An example of information items to be notified at this time is shown in FIG. Here, as connection information necessary for data transmission / reception, “connection destination IP address”, standby “port number”, “session ID” necessary for session control of communication, and the like, content information usable by the application are determined. "Video / audio encoding parameters (types of codecs that can be used)" and "transmission / reception protocols (RTP: Real-time Transport Protocol, UDP: User Datagram Protocol)" to be used are included.

The negotiation function may be realized using a signaling protocol for starting, managing, and ending a session such as SIP (Session Initiation Protocol) or RTSP (Real Time Streaming Protocol).
The application unit 11 creates a quality information table 15 that is a list of content information that can be provided by the application based on the content information of the information acquired by the negotiation function. The items in the quality information table 15 and an example thereof are shown in FIG. The quality information table 15 may be set by the user from the user setting unit 12.

  Next, the application unit 11 notifies the transmission line management unit 17 of information in the application priority reference table 14 necessary for transmission line selection (S403). The items in the application priority reference table 14 and an example thereof are shown in FIG. Each item of the application priority reference table 14 is created from information written from the information acquired by the negotiation function described above and items set by the user from the user setting unit 12. As for the application priority reference table 14, all items set by the user from the user setting unit 12 may be used, or those set in advance in the terminal may be used.

  The transmission line management unit 17 refers to the link status flag in the network interface information table 23 and notifies the communication partner terminal 27 of a list of communicable NICs 25 (S404). The items in the network interface list and an example thereof are shown in FIG. After the NIC information is transmitted and received, a transmission path list existing between the own terminal 26 and the communication partner terminal 27 is created based on the received network interface list and the network interface information table 23 in its own terminal (S405).

  For example, when the number of NICs 25 that can be used by the own terminal 26 is two (NICs 1 to 2) and the number of NICs 25 that can be used by the communication partner terminal 27 is two (NICs 3 to 4), the number of transmission paths is two (the number of the own terminal The number of NICs) × 2 (the number of NICs of the communication partner terminal) × 2 (uplink transmission / downlink transmission) × 2 (whether or not via the home agent HA) is 16. An example of the transmission path list in this example is shown in FIG. The created transmission path list is registered in the transmission path information table 22. As for the creation of the transmission path list, even if the own terminal 26 and the communication partner terminal 27 create each other, only the communication partner side creates only the transmission path list from the communication partner terminal 27 to the own terminal 26. May be notified.

  The transmission path state management unit 20 confirms the round trip path for each network interface between the terminal 26 and the communication partner terminal 27 based on the notified information. For confirmation of the round-trip route, for example, a care-of test response CoT is returned to the care-of test request message CoTI from the terminal 26, and a home test response HoT is returned to the home test request message HoTI via the home agent terminal 28. . At the same time, using the packet for transmitting and receiving the message of the round trip route as a part of the probe packet, the transmission path state (bottleneck physical bandwidth, RTT delay difference, usable bandwidth, packet loss rate, etc.) Measurement is performed (S406, S407).

  Here, the items of the transmission path information table 22 are shown in FIG. Below, explanation of each item and an example of a measuring method are given. FIG. 11B shows an outline of the bottleneck physical bandwidth. FIG. 11B shows one of the transmission paths between the terminal 26 and the communication partner terminal 27, where the line width represents the bandwidth, and the wider the line, the wider the bandwidth. The narrower the line, the narrower the bandwidth. In an IP network, there are various transmission paths in the middle of a path, and therefore it is impossible to provide a uniform bandwidth throughout the entire transmission path. Therefore, by measuring the bandwidth of the bottleneck of the transmission line and determining the content quality based on the result, it is possible to provide a high-quality service at the maximum bit rate at which data can be transmitted and received on the transmission line. Is possible.

  As an example of a method for measuring the physical bandwidth of the bottleneck link, a measurement method using a probe packet by a packet pair transfer method and a packet train transfer method will be described with reference to FIG. When two packets of the same size S are transmitted in close contact from the own terminal 26 and are simultaneously queued on the bottleneck link, ΔT <S / B2. Since the packet arrives at the communication partner terminal 27 while maintaining the interval, ΔT ′ = S / B2. B2 obtained from this equation is the bottleneck physical bandwidth in the transmission path.

  FIG. 11D shows an example in which a round trip path confirmation message, which is also a Mobile IPv6 control message, is used as a part of a packet train probe packet. In this embodiment, the first packet is used as a round trip route confirmation message, and padding is performed because the packet size is small as it is for use as a probe packet. Subsequent probe packets are transferred using the same header as the round-trip route confirmation message, and are transferred along the same route as the round-trip route confirmation message. In this embodiment, a sequence number is added so that the processing is not duplicated. Thus, only the first packet is processed as a round trip route confirmation message.

Next, FIG. 12 shows an example of a method for measuring the RTT delay difference. In FIG. 12, it is assumed that the own terminal 26 includes three NICs 1 to 3 and the communication partner terminal 27 includes the NIC 4 and is connected to the IP network. Since the RTT can be measured by transmitting a packet from the own terminal 26 to the communication partner terminal 27 and further to the own terminal 26, the RTT of NIC1 to NIC4 to NIC1 is RTT1, the RTT of NIC1 to NIC4 to NIC2 is RTT2, NIC1 to NIC4 to NIC3 have an RTT of RTT3, NIC1 → NIC4 one-way delay time ΔT, NIC4 → NIC1 one-way delay time ΔT1, NIC4 → NIC2 one-way delay time ΔT2, NIC4 → NIC3 If the delay time in one direction is ΔT3,
ΔT1 = RTT1−ΔT
ΔT2 = RTT2−ΔT
ΔT3 = RTT3−ΔT
It becomes.

  From the above equations, ΔT1, ΔT2, and ΔT3 are obtained by subtracting ΔT from RTT1, RTT2, and RTT3, respectively. Therefore, comparing RTT1, RTT2, and RTT3, that is, from the communication partner terminal 27 to the own terminal 26 This is synonymous with comparing relative delay differences in one direction. From the above, RTT1, RTT2, and RTT3 can be used as one-way delay differences of NIC4 → NIC1, NIC4 → NIC2, and NIC4 → NIC3, respectively.

  FIG. 13 is a diagram for explaining the available bandwidth. As in FIG. 11B, this is one of the transmission paths between the terminal 26 and the communication partner terminal 27, and the line width represents the width of the bandwidth. This indicates that the wider the line width, the wider the bandwidth, and the narrower the line width, the narrower the bandwidth. The hatched portion indicates that a packet that has already been transmitted and received on the transmission path occupies the bandwidth of each link (cross traffic exists for each link).

  Also in this case, as in the bottleneck physical bandwidth measurement described above, the available bandwidth of the link on the transmission path between the transmission and reception terminals can be measured by using the packet train method for probe packet transfer. Here, using the increasing tendency of the one-way transfer delay between each probe packet, the increasing tendency of the one-way transfer delay is observed when the transmission rate of the probe packet exceeds the available bandwidth. In addition, the available bandwidth can be obtained by repeatedly measuring while changing the transmission rate of the probe packet. Similarly to the measurement of the bottleneck physical bandwidth, the available bandwidth can also be estimated by using the mobile IP round trip confirmation message as part of the probe packet of the packet train.

The packet loss rate is obtained from “packet loss rate = number of packet losses / number of transmitted packets” by using the probe packet used in the above measurement.
The above measurement is performed on the transmission path list registered in the transmission path information table (all transmission paths existing between the own terminal 26 and the communication partner terminal 27). Next, a processing procedure for selecting a transmission path based on the measurement result will be described.

  First, the transmission path state management unit 20 writes transmission path information based on the measurement result acquired by the above-described measurement method into the transmission path information table 22, and the acquired information is transmitted to the transmission path information table 22 and the application priority standard. A transmission path is selected from the table 14 (S409). When the transmission path is selected, the transmission path selection unit 18 refers to the transmission path information table 22 and notifies the application unit 11 of the transmission path information of the selected transmission path (S408). In the first embodiment, the bottleneck physical bandwidth obtained from the transmission path state measurement result is notified to the application unit 11 as a bandwidth that can be allocated to the application. Here, the above value is notified as the bandwidth that can be allocated to the application, but the value obtained as the bottleneck physical bandwidth and the transmission rate of the NIC 25 may be notified as they are.

  The content / communication control unit 13 refers to the quality information table 15 based on the notified transmission path information and determines the content quality in communication (S412). The content / communication control unit 13 exchanges information for determining the type of video / audio and usage parameters according to the determined content quality with the communication partner, and then starts transmission / reception of data (S413), and at the same time, the IP control unit 19 Switches the transmission path by sending the association update message BU for the NIC corresponding to the transmission path selected by the transmission path selection unit 18 (S410, S411).

  It should be noted that although uplink / downlink exists for the transmission path, in this embodiment, it is assumed that the own terminal 26 selects either the uplink / downlink transmission path. Not only in the first embodiment, even if each (the own terminal 26 and the communication partner terminal 27) performs processing so as to select the downlink transmission path, each selects the uplink transmission path instead of the downlink. Also good. In the case of server-client type one-way communication such as video streaming and audio streaming, the transmission path may be selected on the client side. Further, as a transmission path using the same NIC of the own terminal 26 and the communication counterpart terminal 27, as shown in FIG. 10B, a transmission path via a tunnel via the home agent HA and a home agent HA after route optimization There are some that do not go through, but these can be selected based on the application priority criteria.

  As described above, when the communication terminal 10 performs data communication using an application that uses communication such as video and audio through a wireless environment, the priority criteria of the application and the user's preference are determined based on the transmission path information between the communication terminals. In addition, by selecting a transmission path, it is possible to provide a quality service according to the wireless environment and network information of the place where the communication terminal exists. The transmission path may be a medium that can be connected to an IP network, such as a wired LAN represented by Ethernet (registered trademark) as well as wireless.

(Example 2)
Next, referring to FIG. 5, when the communication terminal performs data communication by an application using communication such as video and audio, the communication state (network interface) of the transmission path surrounding the communication terminal changes. The sequence operation of the terminal 26 and the communication partner terminal 27 and the state of each unit will be described. In the description, as in the case of the first embodiment, the reference numerals are used with reference to FIGS.

  The user can move freely taking advantage of the advantages of radio. Here, when the network interface management unit 24 is moving, for example, the radio wave intensity of the NIC (link status flag is “0”) that has been unavailable until now has increased and has changed from Level 2 to Level 4. If it is detected and the threshold value is set to Level 3, the network interface that could not be used can be used. The transmission path management unit 17 is notified that the NIC state has changed, and the notified value is written in the corresponding location of the network interface information table 23 (the link state flag is rewritten from “0” to “1”).

  The transmission path management unit 17 additionally creates a transmission path list added between the own terminal 26 and the communication partner terminal 27 based on the network interface information table 23 (S420). The IP control unit 19 performs a round-trip path check and transmission path state measurement for the added NIC in the same manner as when communication is started in FIG. 4 (S421, S422), and the measurement result is stored in the transmission path information table 22. Registered and notified to the transmission path state management unit 20. A transmission path is determined from the transmission path information obtained in this way and the application priority standard (S423). If the determined transmission path is different from the currently used transmission path (S424 Yes), the transmission path selection unit 18 performs transmission. The transmission path information of the selected transmission path is notified to the application unit 11 with reference to the path information table 22 (S425).

  In the second embodiment, as in the first embodiment, the bottleneck physical bandwidth obtained by measurement as a transmission path state is notified to the application unit 11 as a bandwidth that can be allocated to the application. The content / communication control unit 13 refers to the quality information table 15 based on the notified transmission path information and determines the content quality in communication (S429). If it is determined that content switching is necessary (S430 Yes), the content / communication control unit 13 exchanges information for determining the type of video / audio and usage parameters according to the determined content quality with the communication partner. Later, data transmission / reception is started with the content quality after switching (S431), and at the same time, the IP control unit 19 sends an association update message BU for the NIC corresponding to the transmission path selected by the transmission path selection unit 18. The transmission path is switched at (S426, S427, S428).

  Note that nothing is performed when the selected transmission line matches the currently used transmission line (No in S424). If the selected transmission path is different from the currently used transmission path and the content / communication control unit 13 determines that there is no need to switch the content (No in S430), only the transmission path is switched ( S426, S427).

  In the second embodiment, an example of a change in the radio field strength is given. However, when the dial-up connection such as the mobile phone or the PHS is changed from the established state to the established state (the link state is “OFF”). ”Or“ ON ”) or a new network interface is added, and the network interface may be in the link state“ ON ”or the link state flag is“ 1 ”.

  In the second embodiment, an example in which a NIC is added has been described. However, for example, during movement, the network interface management unit 24 sets a network interface (link status flag “1”) that is currently in communication. It is assumed that the radio field intensity of the radio is weakened, changed from Level 4 to Level 2, and the threshold is set to Level 3. In this case, even when a usable network interface becomes unusable, the transmission path management unit 17 deletes the corresponding transmission path from the transmission path list, and transmits to the updated transmission path list. Select the road, select and switch the contents.

  In the above-described example, an example of a change in radio field strength is given. However, when the dial-up connection such as mobile phone or PHS is changed from the established state to the unestablished state (the link state is “ON”). ”From“ 1 ”to“ OFF ”), the network interface may be deleted (removed from the communication terminal), or the link status flag of a certain network interface may be changed from“ 1 ”to“ 0 ”.

  As described above, while a communication terminal is performing data communication with an application using communication such as video and audio through a wireless environment, a new network interface can be used / not enabled due to a change in the wireless environment. There is a case. In this case, the location of the communication terminal exists by re-selecting the transmission path information according to the transmission path information between the communication terminals, the application priority criteria and the user's preference, and notifying the application of information based on the transmission path. It is possible to provide a quality service according to the wireless environment and network conditions. The transmission path may be a medium that can be connected to an IP network, such as a wired LAN represented by Ethernet (registered trademark) as well as wireless.

(Example 3)
Next, referring to FIG. 6, when the communication terminal performs data communication by an application using communication such as video and audio, the own terminal 26 and the communication partner terminal 27 when the data transfer quality of the transmission path changes. The sequence operation and the state of each part will be described. In the description, as in the case of the first and second embodiments, the reference numerals are used with reference to FIGS.

  At the start of communication, as described in the first embodiment, a transmission path according to the priority standard of the application program is selected from the usable transmission paths, and data communication is started with content quality adapted to the transmission path. After the start of data communication, the transmission line state management unit 20 uses the retransmission packet of the association update message BU periodically transmitted in cooperation with the IP control unit 19 as a part of the probe packet, and transmits the state of the transmission line. Are monitored (S440, S441). The transmission path is measured by the method shown in the first embodiment.

  The transmission line management unit 17 compares the transmission line information obtained by the above measurement with the information registered in the transmission line quality table 21, and determines that it is not necessary to switch the transmission line (No in S442). The transmission path is continuously monitored using the retransmission packet of the association update message BU transmitted by the IP controller without doing anything. If it is determined that the transmission path needs to be switched (S442 Yes), the transmission path status is notified to the application unit 11 based on the transmission path information registered in the transmission path quality table 21 (S446). Here, as in the first embodiment, the bottleneck physical bandwidth is notified as transmission path information as a bandwidth that can be allocated to the application.

  The content / communication control unit 13 refers to the quality information table 15 based on the notified transmission path information, and determines the content quality in communication (S447). If it is determined that content switching is necessary (S448 Yes), the content / communication control unit 13 exchanges information for determining the type of video / audio and usage parameters according to the determined content quality with the communication partner. Later, data transmission / reception is started with the switched content quality (S449). At the same time, the IP control unit 19 switches the transmission line by sending an association update message BU for the NIC corresponding to the transmission line selected by the transmission line selection unit 18 (S443, S444, S445). If the content / communication control unit 13 determines that there is no need to switch the content (No in S448), only the transmission path is switched (S443, S444, S445). However, the transmission path may be set not to be switched according to a user request.

Example 4
Next, FIG. 7 shows another example of selecting step by step based on transmission line information obtained step by step in the procedure of selecting a transmission line at the start of communication.
As a mobile IP mechanism, a mobile terminal registers a new care-of address with the home agent HA every time the network to which it is connected changes. Using this registration procedure as part of the probe packet, the transmission path state between the communication terminal and the home agent HA is measured. In the fourth embodiment, the bottleneck physical bandwidth is measured as the transmission path state, and the method shown in the first embodiment is used as the measurement method.

  The transmission path management unit 17 refers to the network interface information table 23 to identify communicable NICs (S460, S461), performs home registration HR and confirmation ACK processing on the communicable NICs, and communicates simultaneously. The transmission path state between the terminal (own terminal 26 and communication partner terminal 27) and the home agent terminal 28 is measured (S462, S463). As in the first embodiment, as the transmission path, if the own terminal 26 can use two NICs 1-2) and the communication partner terminal 27 can use two NICs (NICs 3-4), An example of the transmission path information table obtained by the transmission path measurement between the communication terminal and the home agent HA is as shown in FIG.

  Upon receiving a communication start request from the user setting unit 12, the application unit 11 notifies information necessary for performing data communication with the application between the own terminal 26 and the communication partner terminal 27 (S464). The application unit 11 creates a quality information table 15 that is a list of content information that can be provided by the application based on the content information of the information acquired by the negotiation function.

  Next, the application unit 11 notifies the transmission line management unit 17 of information in the application priority reference table 14 necessary for transmission line selection (S465). The transmission path management unit 17 refers to the link state flag in the network interface information table 23 and notifies the communication partner of transmission / reception of a list of communicable NICs and information in the application priority reference table 14 (S466). After transmission / reception of NIC information / priority criteria, a transmission path list is created based on the mutual network interface list (S467, 468). An example of the transmission path list is as shown in FIG.

  The transmission path management unit 17 selects a transmission path from the transmission path information and the application priority reference table 14 by associating the transmission path information table 22 with the transmission path list to obtain transmission path information for each transmission path. . The correspondence between the transmission path information and the transmission path list in the fourth embodiment is also shown in FIG. When each terminal can use a plurality of NICs as in the fourth embodiment, it is not possible to select the partner NIC. For example, as shown in FIG. Then, the transmission path is selected based on the result of measuring the transmission path state by the home registration HR (S471). And the selected transmission furnace is notified to the own terminal 26 side (S472).

  The own terminal 26 side selects a transmission path together with the result of the own terminal 26 based on the transmission path (selected NIC) similarly selected on the communication counterpart terminal 27 side (S473). From this information, it is not possible to distinguish between the transmission path via the home agent HA or the direct communication transmission path, but the information obtained by the measurement is transmission path information on the transmission path via the home agent HA. In the fourth embodiment, it is assumed that a transmission path via the home agent HA is selected. In the fourth embodiment, the transmission path via the home agent HA is selected. However, based on the selection result of the transmission path via the home agent HA, a transmission path not via the corresponding home agent HA is used. You may do it.

  In the fourth embodiment, the communication partner terminal 27 uses the home registration HR to acquire the transmission path information. However, the communication partner terminal 27 has a function of acquiring the transmission path information. If there is not, regarding the selection of the NIC in the communication partner terminal 27, the transmission path may be determined based on information obtained from the network interface information such as the transmission speed of the NIC.

  When the transmission path is selected, the transmission path selection unit 18 refers to the transmission path information table 22 and notifies the application unit 11 of the transmission path information of the selected transmission path (S474). The content / communication control unit 13 determines the content quality with reference to the quality information table 15 based on the notified transmission path information (S481). The content / communication control unit 13 starts data transmission / reception after exchanging information for determining the type of video / audio and usage parameters according to the determined content quality with the communication partner terminal (S482), and at the same time, the IP control unit 19 switches the transmission path by sending an association update message BU for the NIC corresponding to the transmission path selected by the transmission path selection unit 18 (S475, S476, S477, S478, S479, S480).

  In the fourth embodiment, the transmission path is selected based on the own terminal 26 to the home agent terminal 28 and the communication partner terminal 27 to the home agent terminal 28 or based on the network interface information. After the transmission line is selected, an end-to-end transmission line state may be acquired, and processing for reselecting the transmission line based on the information may be added.

  As described above, by using the simple measurement result, it is possible to select a transmission line and start data communication before a detailed transmission line measurement result is obtained. Furthermore, by selecting the transmission path again based on the detailed transmission path result obtained after the start of data communication, it becomes possible to provide a service that more suits the application and user's preference. In addition, by selecting NICs having different uplink / downlink transmission paths according to the application priority standards and the transmission path conditions, it is possible to use different transmission paths according to the preference of the application and the user. In addition, the transmission line selection unit does not select one transmission line, but rather prioritizes relative transmission lines (weights each item, and assigns each transmission line based on that weight). It is also possible to give points to the communication partner by notifying the communication partner of the priority by calculating the points and assigning the priority from the highest point).

  In the fourth embodiment, the example in which the communication state changes in the own terminal 26 has been described. However, the same control is performed when the communication state changes in the communication partner terminal 27, so that the transmission path It is possible to provide a quality service according to the user's communication status, such as the selection of the application and the linkage of the application.

It is a schematic diagram explaining Mobile IPv6 utilized with the communication system and communication method of this invention. It is a conceptual diagram of the accessible area corresponding to the wireless base station and wireless access point which are applied to the communication system and communication method of this invention. It is a functional block diagram explaining the structural example of the communication terminal used by this invention. It is a functional block diagram explaining the structural example of the home agent terminal used by this invention. It is a figure explaining an example of the operation | movement sequence at the time of the communication start in Example 1. FIG. It is a figure explaining an example of the operation | movement sequence at the time of the network interface state change in Example 2. FIG. FIG. 10 is a diagram illustrating an example of an operation sequence when transfer quality changes in the third embodiment. It is a figure explaining the other example of the operation | movement sequence at the time of the communication start in Example 4 (at the time of simple measurement utilization). It is a figure which shows an example of the network interface information table in an Example. It is a figure which shows an example (A) of a communication information notification item in an Example, an example (B) of a quality information table item, and an example (C) of an application priority reference table item. It is a figure which shows an example (A) of a network interface list in an Example, and an example (B) of a transmission list. Example of items in transmission path information table in embodiment (A), outline of bottleneck physical bandwidth (B), example of measurement method of physical bandwidth of bottleneck link (C), round-trip confirmation message in probe packet It is a figure which shows an example (D) used for a part. It is a figure which shows an example of the method of measuring the RTT delay difference in an Example. It is a figure explaining the available bandwidth in an Example. It is a figure which shows the transmission-line information table obtained by transmission-line measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Communication terminal, 11 ... Application part, 12 ... User setting part, 13 ... Content / communication control part, 14 ... Application priority reference table, 15 ... Quality information table, 16 ... Transmission path control part, 17 ... Transmission path management part , 18 ... transmission path selection section, 19 ... IP control section, 20 ... transmission path status management section, 21 ... transmission path quality table, 22 ... transmission path information table, 23 ... network interface information table, 24 ... network interface management section, 25 ... Network interface card (NIC), 26 ... Own terminal, 27 ... Communication partner terminal, 28 ... Home agent terminal, 29 ... Network.

Claims (18)

A communication terminal having a plurality of network interfaces connectable to a plurality of transmission paths is a communication system using a plurality of transmission paths,
At least one of the communication terminals is a mobile terminal under the control of a home agent;
And a network interface management unit in which the plurality of detecting the communicable network interface of the network interface, obtain network interface information about the predetermined attribute of said plurality of network interfaces from the network, to register with the network interface information table,
A transmission path management unit that notifies each other of the communicable network interface and the communicable network interface, creates a transmission path list that exists between the communication counterparts, and registers the transmission path list in a transmission path information table; ,
A transmission path state management unit that acquires information on the state of the transmission path corresponding to the transmission path list using a control message of Mobile IP, and writes the information in the transmission path information table as transmission path information;
A transmission path selecting unit which determines the priority criteria set for each application program for data communication priority of the transmission path, to determine a transfer sending passage based on one of the network interface information and the transmission path information,
And performing data communication via the determined transmission path.   The communication system according to claim 1, wherein the communication terminals that communicate with each other include a fixed terminal. 3. The communication system according to claim 1, wherein the information on the state of the transmission path is acquired stepwise in an operation sequence from the start of communication to data communication. Decision of the transmission path, determined based on the priority of the transmission path for each transmission path conditions stepwise acquisition, transmission path which is determined to be different from the transmission path in the communication, the newly determined The communication system according to claim 3 , wherein the communication system is switched to another transmission line. The communication system according to claim 1, wherein the network interface information includes a network interface transmission rate. 6. The communication system according to claim 5 , wherein when the network interface transmission rate is different between upstream and downstream, each is acquired as different information. The communication according to any one of claims 1 to 6 , wherein the transmission path information includes a bottleneck physical bandwidth between a network to which the plurality of network interfaces are connected and a communication partner. system. The communication system according to claim 1 , wherein the transmission path information includes an available bandwidth between a network to which the plurality of network interfaces are connected and a communication partner. Wherein the transmission path information, any one of the preceding claims, wherein the plurality of network interfaces include a RTT (Round Trip Time) delay difference between the connected transmission path with the communication partner The communication system according to 1. The communication system according to claim 1 , wherein the transmission path information includes a communication cost between a transmission path to which the plurality of network interfaces are connected and a communication partner. In the determination of the priority of the transmission path, claim 1, wherein a in the case of the transmission path characteristics are different asymmetric communication network uplink / downlink, that can select a transmission path different from the uplink / downlink by the priority criteria The communication system according to any one of the above. In the determination of the priority of the transmission path, when the requested bandwidth is used for the priority criteria of claims 1 to 10 wherein the requested bandwidth is characterized in that it is more set for each application program The communication system according to any one of the above. The data type of the data communication, content and communications control for determining the quality information which is set for each application program, by referring to content quality the quality information table based on the transmission path information concerning the transmission path the determined The communication system according to claim 1, further comprising a unit . After the start of data communication, it detects that the state of the network interface that is not in data communication has changed , and acquires network interface information related to a predetermined attribute of the plurality of network interfaces ,
Again, a transmission path list existing between the communicable network interface and the communication partner's communicable network interface is created, and transmission path information relating to the status of the transmission path corresponding to the newly created transmission path list is obtained. Get and
Said determining including a transmission path in the communication based on the priority of the transmission path to one of the information related to the network interface information and the transmission path information, the transmission path the determined is is different from the transmission path in the communication The communication system according to claim 1 , wherein the communication path is switched to a newly determined transmission path. Simultaneously with the switching of the transmission path, the quality information set for each application and the transmission path information regarding the determined transmission path are referred to, the content quality is determined based on the information, and the determined content quality is obtained. communication system according to claim 14, wherein the TURMERIC line data communications based. After starting the data communication, it detects a state change of the data transmission quality of the transmission path in use, according to any preceding of claims 1 to 15, characterized in that it comprises a switching the Kiden sending passage Communications system. The communication system according to claim 16 , wherein a control message of Mobile IP is used for detecting a change in state of data transfer quality of the transmission path in use. A communication terminal having a plurality of network interfaces connectable to a plurality of transmission paths is a communication method using a plurality of transmission paths,
At least one of the communication terminals is a mobile terminal under the control of a home agent,
The network interface management unit detects a communicable network interface among the plurality of network interfaces, acquires network interface information related to a predetermined attribute of the plurality of network interfaces from the network, and registers it in the network interface information table,
The transmission path management unit notifies the communication partner of the communicable network interface and the communication partner's communicable network interface to each other , creates a transmission path list existing between the communication partners , and transmits transmission path information. Register in the table,
The transmission path state management unit obtains information on the state of the transmission path corresponding to the transmission path list using a control message of Mobile IP, and writes it in the transmission path information table as transmission path information.
The transmission line selection unit, the priority of the transmission path is determined by the priority criteria set for each application program for data communication, a transfer sending passage is determined based on any of the network interface information and the transmission path information ,
A communication method comprising performing data communication via the determined transmission path.

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