JPWO2007063901A1 - Wireless communication system and wireless communication method - Google Patents

Abstract

Provided is a communication system and a communication method in which transmission path switching and application switching are linked in response to a change in communication status accompanying movement of a user in a mobile environment. Changes in the communication status associated with the movement of the user are constantly monitored, and the transmission path is switched as the transmission path changes. At that time, it is possible to select the transmission path suitable for the application by acquiring the transmission path status between the own terminal and the communication partner terminal and comparing it with the priority standard for each application, and at the same time change to the content suitable for the transmission path. By doing so, it is possible to provide a service according to the communication status.

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 wireless communication system for providing users with conversational and streaming application services, and The present invention relates to a wireless communication 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 (Mobile IPv6, Lin6, etc.) that enable continuous wireless communication between different networks, services are seamlessly selected when communication is switched by selecting the optimal communication environment each time it is used. It is becoming possible to receive. 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, data communication while moving wirelessly is unstable or unstable when the radio wave intensity changes with the movement, communication is interrupted, or when moving to a different wireless network. Therefore, a method has been proposed in which network switching control and data quality control are performed by providing means for notifying the upper layer of such lower layer information (see Patent Document 2).

It is also possible to estimate the end-to-end bandwidth, available bandwidth, and usage between communication terminals. For example, a method has been proposed in which an ICMP (Internet Control Message Protocol) time stamp request is transmitted to each router on the route, and QoS (Quality of Service) is estimated based on the difference between the obtained time stamp values. (See Patent Document 3).
JP 2004-272563 A JP 2004-266330 A JP 2004-312725 A

  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. Moreover, the parameter used as a priority standard may differ with applications to be used. For example, in the case of video streaming, the wider the usable bandwidth, the better. For VoIP (Voice over Internet Protocol), the priority for RTT (Round Trip Time) is high, and it is sufficient that the bandwidth can be secured to some extent. It is assumed that the request for the parameter for determining the priority order varies depending on the application.

  In addition, with the technique disclosed in Patent Document 2, it is possible to acquire information (communication intensity, modulation method, wireless congestion, network prefix, reception buffer size, etc.) regarding the communication status in the wireless network. . However, in a network in which a network environment in which a portion other than the last one hop becomes a bottleneck is mixed, it is necessary to acquire end-to-end transmission path information between communication terminals. As an example of the transmission path as described above, there is a representative of the use of a wireless LAN in an ADSL service that is becoming popular in each home recently.

  In such a transmission path, the ADSL part in the middle of the path may become a bottleneck of the transmission path band. Furthermore, there are cases in which a transmission path such as ADSL or high-speed wireless communication (FOMA, CDMA2000, etc.) having an asymmetric upstream / downstream band is used. In this case, the transmission path state may be different between uplink / downlink, and when bidirectional communication is taken into consideration, it is necessary to select different transmission paths for uplink and downlink. .

Further, in the technique disclosed in Patent Document 3, in order to estimate the end-to-end transmission path state, it is necessary to transmit a large number of probe packets and to statistically process the result. It takes a lot of time to estimate the 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.
The present invention provides a wireless communication system and a wireless communication method for efficiently solving the various problems described above.

  In the wireless communication system of the present invention, a communication terminal having a network interface connectable to a plurality of transmission paths detects a network interface that can communicate among a plurality of network interfaces in a communication system that uses the plurality of transmission paths. Acquire network interface information related to predetermined attributes of multiple network interfaces, create a transmission path list that exists between the network interface that can communicate and the network interface that can communicate with the communication partner, and transmit the network interface information Corresponding to the path list, and acquiring at least one of the bottleneck physical bandwidth, cross traffic, bandwidth variation rate, bandwidth deviation rate as the transmission path information relating to the status of the transmission path corresponding to the transmission path list, Communicate the priority of It determined based on the set priority criteria for each application program for road information and data communications, to determine the transmission path, and performs data communication via a transmission path which is determined.

The bottleneck physical bandwidth is obtained by closely transmitting a probe packet of the same size S from the transmission terminal to the reception terminal, receiving the probe packet at the reception terminal, and measuring the bottle interval from the measured probe packet reception interval ΔT. Neck physical bandwidth B is B = S / ΔT
Calculate based on
Also, in the means for obtaining the bottleneck physical bandwidth, the pair of probe packets of size S and the pair of packets of size S ′ smaller than size S are transmitted as probe packets, and the size measured at the receiving terminal If the delay time of the probe packet of S is ΔT ′, the delay time of the probe packet of size S ′ is ΔT ″, and ΔT ″> ΔT ′, it is determined that cross traffic exists.

In addition, when n measurement results are obtained from the means for obtaining the bottleneck physical bandwidth, the bandwidth variation rate CV is calculated as “CV = standard deviation / phase from the standard deviation and arithmetic mean of the obtained measurement results. Calculated based on "arithmetic average x 100".
Further, when the bottleneck bandwidth obtained from the means for obtaining the bottleneck physical bandwidth is BWT, the transmission path speed in the upstream direction of the network interface on the transmission side of the measured transmission path and the network interface on the reception side If the smaller value of the downstream transmission rates is Z, the band deviation rate BWσ is calculated based on “BWσ (%) = | BWT−Z | / Z”.

  The transmission path information includes a bottleneck physical bandwidth, usable bandwidth, RTT, communication cost, presence / absence of cross traffic, bandwidth fluctuation rate, bandwidth deviation between a network to which a plurality of network interfaces are connected and a communication partner. Rate, transmission path QoS support, and the like. The priority of the transmission path is determined every time the transmission path is determined, and is determined based on the priority standard set for each application program that performs data communication. When an asymmetric communication network having different uplink / downlink channel characteristics is included, different uplink / downlink transmission channels can be selected according to 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 things that take time to acquire transmission path information, and for such things, setting the measurement time threshold value, the measurement results at that time (presence / absence of cross traffic, radio wave intensity, etc.) and the above network interface information Alternatively, the priority of the transmission path is determined based on the priority of the network interface previously set for the terminal by the user or the like.
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. In addition, after data communication, when the status of the network interface that is not in data communication, the transmission path status of the transmission path being used, the wireless modulation method, etc., change the priority of the transmission path again and determine the highest priority. Switch to a higher 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. At the same time, it is possible to provide a quality service according to the location where the communication terminal exists by selecting content of quality matching the network information.

  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, the state of the transmission line is acquired again due to a change in the communication state of the transmission line, and the transmission line is selected again according to the priority standard or user preference set for each application. Thus, even in a communication environment that changes from moment to moment, it is possible to provide a service with a quality that is optimal for the communication environment where the communication terminal exists.

It is a figure which shows the example of whole structure of the network which can apply this embodiment. It is a conceptual diagram of the accessible area corresponding to the base station of the wireless network which can apply this embodiment. It is a functional block diagram which shows the example of an internal structure of the communication terminal by this invention. FIG. 3 is an operation sequence diagram illustrating operations of respective units when communication terminal 10 starts communication. It is a sequence diagram which shows operation | movement of each part when the communication state of the network interface card of the communication terminal 10 changes. It is a figure which shows an example of the network interface information table in a present Example. It is a figure which shows an example (A) of a communication information notification format in this Example, an example (B) of a quality information table, and an example (C) of an item of an application priority reference table. It is a figure which shows an example (A) of a network interface list, and an example (B) of a transmission line list in a present Example. It is a figure which shows an example of the transmission-line information table in a present Example. It is a figure which shows the outline | summary (A) of a bottleneck physical bandwidth in this Example, and an example (B) of a measuring method of a bottleneck physical bandwidth. It is a figure which shows an example of the measuring method of the RTT delay difference in a present Example. It is a figure which shows the outline | summary of the available bandwidth in a present Example. It is a figure which shows an example (A) of a network in which a cross traffic does not exist, and an example (B) of a network in which a cross traffic exists in a present Example. It is a flowchart which shows an example of the process sequence of the transmission line selection at the time of the communication start in a present Example. It is a flowchart which shows an example of the process sequence of the transmission line selection in a present Example. It is a flowchart which shows an example of the process sequence following FIG. 15A. It is a figure which shows an example in case a different transmission path is selected by the uplink / downlink in a present Example. It is a figure which shows an example (A) of a network interface information table in this example, an example (B) of a transmission line information table, and another example (C) of a transmission line information table. It is a figure which shows an example of the application priority reference table in a present Example. It is a figure which shows an example (A) of the network interface information notified in a present Example, an example (B) of the list | wrist of the added transmission line, and another example (C) of the network interface information notified. It is a flowchart in case QoS is supported by the transmission line selection in a present Example. It is a figure which shows the other example (A) of the application reference | standard table in a present Example, and the other example (B) of a transmission-line information table.

Explanation of symbols

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

First, the overall configuration of a wireless network to which the wireless communication system according to the present invention is applied and its accessible area will be described with reference to FIGS.
In FIG. 1, networks 1 to n are networks in units of network segments such as LAN and WAN. For example, the network 1 includes a plurality of wireless base stations, and the network 2 includes a plurality of wireless access points (APs). I can do it. That is, each of the networks 1 to n is, for example, a public mobile phone network, a self-operated private wireless LAN, a hot spot, a home wireless network, or the like, and is assumed to be an IP-based network here. These networks for each network segment are connected to a core network represented by the Internet.

  The communication terminals 1 to n perform communication such as video / audio communication between one-to-one or a plurality of terminals. For example, even if the communication terminal 1 moves and changes from a state in which the radio base station 1 receives radio waves to a state in which the radio base station 2 receives radio waves, a handover is performed between the radio base stations 1 and 2. Thus, the communication terminal 1 can continue the communication before the movement even after the movement. The same applies when moving from the connection range of the wireless access point AP1 to the connection range of the wireless access point AP2. In handover between wireless access points, authentication information handover may be used together.

  Furthermore, even if the communication terminal moves between network segments, handover at the network layer is performed and communication can be continued. For example, it is assumed that the communication terminal 2 moves and changes from a state connected to the wireless base station 2 to a state connected to the wireless access point AP1. Even in this case, the communication terminal 2 includes a network interface card (NIC) that can be connected to each of the wireless base station 2 and the wireless access point AP1. If it is compatible with mobile IP (IETF: Internet Engineering Task Force) RFC3775, the application unit can continue communication processing regardless of having moved to a different network.

  For handover between network segments, the IP control unit supports Lin6 (IETF Draft-Teraoka-ipng-Lin6-01), the communication control unit supports the handover while maintaining the session, and similar functions. It may be a technology to be realized. As for movement between network segments, even when the wireless access point AP1 and the wireless access point AP2 are configured with different network segments, the handover technique as described above is used to perform handover between the wireless access points. It is possible to continue communication.

  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 a LAN and a 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. . These networks for each network segment are IP-based networks, and are connected to the core networks as in FIG.

  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 NIC that can be connected to the mobile base station 1, the wireless AP 2, and the PHS base station 3. In the wireless LAN area 2, the network is connected to each other via the mobile base station 1, the wireless AP 2, and the PHS base station 3. 1 to 3 can be connected.

  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, communication can be continued by applying the above-described technology such as mobile IP.

  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 the mobile / PHS area 4 is connected to the network 3 via the PHS base station 3 and moved to the mobile area 1 that can be connected only to the mobile base station 1, Even when moving to the PHS area 3 that can be connected only to the PHS base station 3 from the state of being connected to the network 1 via 1, it is possible to continue communication by applying the above-described technology such as mobile IP. is there.

  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 according to the application being used. Here, although mobile and PHS wireless LAN are cited as wireless communication systems, an IP-based network such as Bluetooth that is short-range communication or IMT (International Mobile Telecommunication) -2000 that is a broadband mobile communication system is used. As long as it can be provided, any wireless communication method may be used.

  In addition, as a form of communication, 1) When the transmission side is a communication terminal that moves and the reception side is a communication terminal that is fixedly connected, 2) When the transmission side is a fixedly connected communication terminal and the communication side that the reception side moves In some cases, 3) there are cases where both the transmission side and the reception side of communication are mobile communication terminals (communication terminals 1 and 2). 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. FIG. 3 is a functional block diagram showing an internal configuration example of the communication terminal according to the present invention, FIG. 4 is a diagram showing an operation sequence at the start of communication, and FIG. 5 is a diagram showing an operation sequence when the communication state of the network interface card is changed. It is.
In the figure, 10 is a communication terminal, 11 is an application unit, 12 is a user setting unit, 13 is a communication control unit, 14 is a content control unit, 15 is an application priority reference table, 16 is a quality information table, and 17 is a transmission path control unit. , 18 is a transmission path manager, 19 is a transmission path selector, 20 is an IP controller, 21 is a transmission path information table, 22 is a network interface information table, 23 is a transmission path status manager, 24 is a network interface manager, Reference numeral 25 denotes a network interface card (NIC), 26 denotes its own terminal, 27 denotes a communication partner terminal, and 28 denotes a network.

  The communication terminal 10 used in the wireless communication system of the present invention includes an application unit 11 that performs transmission / reception and processing of actual communication data, a network interface card 25, and a transmission path control unit 17 that performs state management and control of transmission paths. Consists of. 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, as long as the terminal includes 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 application request information to the transmission path control unit 17 based on the service definition information and the application priority reference table 15. The transmission path control unit 17 is included in the application program or used by the application program. The transmission path control unit 17 receives the application request information from the application unit 11 and obtains the application request information from the application unit 11 and the network interface information obtained by the network interface management unit 24 and the transmission path state management unit 23. Based on the received transmission path information, the transmission path selection unit 19 determines the transmission path.

  Further, the transmission path selection unit 19 returns information regarding the selected transmission path to the application unit 11. In response to the information, the content control unit 14 refers to the quality information table 16 to determine the content, and the communication control unit 13 transmits and receives data to provide the service. Each unit of the communication terminal may be realized by any of hardware, software, and a combination thereof.

  Next, each part of the communication terminal described above will be described in more detail. The network interface management unit 24 manages a network interface card (hereinafter referred to as 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 22.

  The network interface information table 22 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 22 is shown in FIG. The network interface management unit 24 acquires the items described in FIG. 6 from the device information of the NIC every time the NIC state changes.

  The transmission path state management unit 23 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, for each detected transmission path, the transmission path status (for example, bottleneck physical bandwidth, usable bandwidth, RTT delay difference, packet loss rate, presence / absence of cross traffic, bandwidth fluctuation rate, bandwidth deviation rate, etc.) And is registered in the transmission path information table 21. When the NIC information is updated, the path is detected and the transmission path information is 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 18 uses the transmission path information acquired by the transmission path state management unit 23 and the application request information received from the application unit 11 (for example, request bandwidth, request delay, fee, priority transmission path, etc.) Select the optimal transmission path for As a selection result, even if one transmission path most suitable for the application is selected, 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, charge, etc.) of the selected transmission path is returned to the application unit 11.

  The content control unit 14 refers to the quality information table 16 on the basis of the transmission path state answered by the transmission path management unit 18 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 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. In addition, it also transmits and receives application information (such as a standby port number and usable codec type) with a 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 a user to set a communication terminal and set and operate the application priority reference table 15. 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 20 sets address information and the like necessary for transmitting data to the IP network (FIGS. 1 and 2), and transmits / receives the created data to / from the actual network via the NIC 25. The communication terminal 10 is connected to a network and can move while maintaining the connection with the network.

  In the communication terminal 10 described above, when the communication terminal is activated, the network interface management unit 24 provides information on attributes of a plurality of network interfaces (for example, communication card names, transmission speeds, radio wave strengths, link states, modulation methods, etc.). get. Network interfaces that can communicate simultaneously are detected and registered in the network interface information table 22. Examples of the method for detecting the network interface include determination based on comparison between radio wave intensity and a threshold, change in link state, and the like.

  After the communication terminal 10 is activated, the network interface management unit 24 monitors the addition / deletion of the network interface and the availability / non-acceptance of the communication to detect that the state has changed, and updates the network interface information table 22 one by one. At the start of communication of the application, the communication terminal 10 obtains information on the usable content by notifying the content information that can be used with the communication partner, registers the information in the quality information table 16, and sets a preset application. Are registered in the application priority criteria table 15 together with information on the priority criteria (requested bandwidth, minimum required bandwidth, allowable delay, etc.).

  Next, with reference to the network interface information table 22, information on communicable NICs is transmitted to the communication partner. The received communication terminal refers to the transmitted NIC information and the network interface information table 22 of its own terminal, and extracts a transmission path (path) existing between the communication terminals. At this time, the acquired transmission path information (for example, presence / absence of cross traffic, band fluctuation rate, band deviation rate, QoS support / not support) is registered in the transmission path information table 21, and the transmission path information table 21 Based on the information and the information in the network interface information table 22, the application priority criteria table 15 filters the application program to select a path for starting communication.

  When a transmission path is selected, the transmission path selection unit 19 transmits the transmission path information of the transmission path selected with reference to the transmission path information table 21 to the content control unit 14. The content control unit 14 determines the content quality from the quality information table 16 based on the received transmission path information. The communication control unit 13 starts transmission / reception of the determined content, and at the same time, the IP control unit 20 switches to the transmission path selected by the transmission path selection unit 19. By performing the above-described processing, it is possible to perform data communication using a transmission path selected from a certain amount of information before measuring a detailed transmission path state. In parallel with the above processing, each transmission path information (bottleneck bandwidth, RTT delay difference, etc.) is sequentially acquired for the extracted path step by step and registered in each transmission path information table 21. .

  The transmission path selection unit 19 filters the data in the transmission path information table 21 with the application priority reference table 15 to select a transmission path that is optimal for the application request. For example, when video streaming is activated as an application, the bandwidth is set as the priority standard, so the transmission path with the widest bandwidth is selected. At this time, it is also possible to select NICs having different uplink / downlink transmission paths according to priority criteria. Also, the transmission path selection unit 19 does not select one transmission path, but gives a priority to the communication partner by giving a relative priority to the transmission path, and determines the transmission path to the communication partner. It is also possible to make it.

  If the transmission line selected at this time is closer to the user's request than the state of the transmission line currently in use, the transmission line may be switched to the selected transmission line. That is, when the transmission path determined for each transmission path state acquired in stages is different from the transmission path in communication, the transmission path is switched to the newly determined transmission path. In this case, the transmission path information of the transmission path selected with reference to the transmission path information table 21 is transmitted again to the content control unit 14. However, even if the determined transmission path is different from the transmission path in communication, if it is far from or equal to the request from the user than the state of the currently used transmission path, the newly determined transmission path There are cases where switching is not performed.

  The content control unit 14 determines the content quality from the quality information table 16 based on the received transmission path information. The communication control unit 13 starts transmission / reception of the determined content, and at the same time, the IP control unit 20 switches to the transmission path selected by the transmission path selection unit 19. By executing the above processing, data communication of the selected content is performed via the determined transmission path, and switching of the transmission path and application linkage are realized.

  When the network interface management unit 24 detects that the state of the NIC 25 has changed, the information of the newly acquired NIC 25 is registered or deleted in the network interface information table 22 and the updated NIC 25 information is deleted. Send information to the other party. The received communication terminal refers to the updated NIC 25 information and the network interface information table 22 of its own terminal, and detects a transmission path (path) existing between the communication terminals.

  When a transmission line is added, each transmission line state (bottleneck bandwidth, RTT delay difference, etc.) is acquired for the newly extracted transmission line, registered in each transmission line information table 21, and communicated. The transmission path is selected again in the same manner as at the start. Also, when used in bidirectional communication, the priority of the transmission path is determined for each of the uplink / downlink, the transmission path with the highest priority is determined for each, and the determined transmission path is determined. Data communication. If a communication session via another transmission path has already been established, each transmission path is switched while the communication session is maintained.

  FIG. 4 is an operation sequence diagram illustrating the operation of each unit at the start of communication of the communication terminal 10 of FIG. 3 described above, and FIG. 5 is a diagram illustrating an operation sequence when the communication state of the NIC 25 changes. First, an operation sequence at the start of communication will be described. In FIG. 4, the own terminal 26 is a communication terminal on the transmission side that starts communication, and the communication partner terminal 27 indicates a communication terminal on the reception side with respect to the communication terminal on the transmission side. It is assumed that a plurality of network interfaces connectable to the IP network 28 are provided. In addition, data communication for communication such as video and audio is performed via the wireless access point and the wireless base station described with reference to FIGS.

  The connection form may be one-to-one or a communication form such as a multipoint conference with a plurality of people. Data communication may also be server-client type one-way communication or two-way communication such as a telephone. In FIG. 5, the own terminal 26 is a communication terminal that detects a change in the communication state of the NIC, and the communication partner terminal 27 is a communication terminal with which the own terminal 26 is communicating. In this case, the own terminal 26 and the communication partner terminal 27 may be either a transmitting terminal or a receiving terminal. It can be said that the communication form is the same as that of the communication terminal of FIG. Moreover, each communication terminal may be a communication terminal in which one or both has only one NIC.

  First, referring to FIG. 4 (see FIG. 3), each part of the own terminal 26 and the communication partner terminal 27 at the start of communication when the communication terminal performs data communication by an application using communication such as video and audio. The operation will be described. For example, if the transmission path management unit 18 is installed as middleware used for an application program, the network interface management unit 24 may provide information on the attributes of the NIC provided in the own terminal 26 when the program is started ( For example, the communication card name, transmission speed, radio wave intensity, link state, modulation method, MTU, etc.) are acquired.

  Simultaneously with the acquisition of this information, a communicable NIC is detected and registered in the network interface information table 22 (S401). After this registration, the network interface management unit 24 constantly monitors the communication state of the NIC, and when the state changes, the network interface management unit 24 writes for each time the item of the network interface information table 22 is updated, Only the changed item is notified to the transmission line management unit 18. At this time, all items may be notified. FIG. 6 shows an example of items registered in the network interface information table 22 and their values.

  Examples of the NIC detection method include determination based on comparison between radio wave intensity and a threshold value, link status, and the like. As an example of detection by radio wave intensity, when the threshold is Level 3, and the radio wave intensity is equal to or higher than Level 3, the flag is “1” (1 when the network interface is usable as a flag, and when the network interface is not usable) Is written in the position of the link status flag in the network interface information table 22.

  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 preliminarily built in the communication terminal, 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 22, and when the dial-up connection is not established, an “OFF” flag is written. . The activation timing of the transmission path management unit 18 may be activated until the application starts communication regardless of whether the communication terminal 10 is activated or the application is activated. Even when the transmission line management unit 18 is included in the application, the activation timing of the transmission line management unit 18 may be the same as described above.

  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 IP address may be an IPv4 (Internet Protocol Version 4) address or an IPv6 (Internet Protocol Version 6) address.

  The application unit 11 creates a quality information table 16 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 16 and an example thereof are shown in FIG. The quality information table 16 may be set by the user from the user setting unit 12.

  Next, the application unit 11 notifies the transmission line management unit 18 of information in the application priority reference table 15 necessary for transmission line selection (S403, S404). The items in the application priority reference table 15 and an example thereof are shown in FIG. Each item in the application priority reference table 15 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 15, 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 18 refers to the link status flag in the network interface information table 22 and notifies the communication partner terminal 27 of a list of communicable NICs (S406). The items in the network interface list and an example thereof are shown in FIG. The communication partner terminal 27 creates a transmission path list that exists between the own terminal and the communication partner terminal based on the received network interface list and the network interface information table 22 in its own terminal.

  For example, when the number of NICs that can be used by the own terminal 26 is three (NICs 1 to 3) and the number of NICs that can be used by the communication partner terminal 27 is two (NICs 4 to 5), the number of transmission paths is three (of the own terminal The number of NICs) × 2 (the number of NICs of the communication partner terminal) × 2 (uplink transmission line / downlink transmission line). An example of the transmission path list in this example is shown in FIG. The created transmission path list is notified from the communication partner terminal 27 to the own terminal 26, registered in each transmission path information table 21 (S407, S408), and notified to each transmission path status management unit 23. (S409, S4100).

  The transmission path state management unit 23 performs simple measurement (the presence / absence of cross traffic, a band variation rate, a band deviation rate, etc.) of each transmission path based on the notified information (S411). Further, after the simple measurement is completed, detailed transmission path measurement is performed (S420). Detailed transmission path measurement (bottleneck physical bandwidth, RTT delay difference, usable bandwidth, packet loss rate, etc.) may not be performed at this point.

  The items in the transmission path information table 21 are shown in FIG. Below, explanation of each item and an example of a measuring method are given. FIG. 10A shows an outline of the bottleneck physical bandwidth. FIG. 10A 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. A plurality of (for example, two) probe packets of the same size S are transmitted in close contact from the own terminal (transmission terminal) 26 to the communication partner terminal (reception terminal) 27, and are simultaneously queued on the bottleneck link. And ΔT <S / B2. Since the probe 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.
The receiving terminal receives the probe packet, measures its delay time ΔT ′, and repeats the continuous transmission of the probe packet while changing the number of probe packets at the transmitting terminal. The receiving terminal sequentially measures the delay time ΔT ′ of the received probe packet and calculates an average value for the obtained series of data. In this embodiment, the average value is used as a method for calculating the bottleneck physical bandwidth from the obtained series of data. However, a statistical method such as a deviation value or a coefficient of variation, or a calculation method combining them is used. It doesn't matter.

Next, FIG. 11 shows an example of a method for measuring the RTT delay difference. In FIG. 11, it is assumed that the own terminal 26 includes three NICs 1 to 3 and the communication counterpart 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 NIC4 to NIC3 RTT is RTT3, NIC1 → NIC4 one-way delay time is ΔT, NIC4 → NIC1 one-way delay time is ΔT1, NIC4 → NIC2 one-way delay time is ΔT2, NIC4 → NIC3 one-way When the direction delay time 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. 12 is a diagram for explaining the available bandwidth. As in FIG. 10A, this is one of the transmission paths between the own 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. 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.

  Next, an example of a method for detecting cross traffic will be described with reference to FIGS. 13 (A) and 13 (B). Also in this case, the cross traffic is detected by using the packet pair transfer method and the packet train transfer method for the transfer of the probe packet in the same manner as the measurement of the bottleneck physical bandwidth described above. FIG. 13A shows an example in which probe packets are transferred using a packet pair transfer method when there is no cross traffic. Here, two probe packets of different sizes S and S ′ (S> S ′) are used. The data is transmitted from the terminal 26 in close contact. Here, S ′ ≦ B2 × ΔT. In this case, if the packet pair of S ′ is small in size and is not queued by the bottleneck link, it arrives at the communication partner terminal 27 while maintaining the packet interval (delay time) of ΔT.

FIG. 13B shows an example in which a probe packet is transferred using a packet pair transfer method when cross traffic with a packet size C exists. Similarly, two probe packets of different sizes S and S ′ are respectively transmitted to the own terminal. (Transmission terminal) 26 transmits the data closely. Here, if S ′> S−C, when the cross traffic of the packet size C enters between the packet pairs of the size S ′, the delay time (reception interval) is
ΔT ″ = (S ′ + C) / B2
ΔT ′ = S / B2 (corresponding to a delay time of size S)
ΔT ″> ΔT ′
Thus, when the above measurement result is confirmed on the communication partner terminal (reception terminal) 27 side, it is possible to confirm that cross traffic exists.

  Next, an example of a method for obtaining the band variation rate (BWCV) is shown below. The bottleneck link is transmitted by transmitting the probe packet from the own terminal 26 to the communication partner terminal 27 using the method of measuring the bottleneck physical bandwidth using the probe packet by the packet pair transfer method and the packet train transfer method described above. It is possible to acquire the physical bandwidth. However, when cross traffic exists as described above, it is assumed that the measurement results vary due to the influence of the packet pair and the packet train. Here, it is assumed that n measurement results are obtained. Assuming that each bottleneck physical bandwidth is BW1, BW2, BW3,... BWn, the arithmetic mean is

It becomes. Since the coefficient of variation (CV) obtained from these values is an index representing relative dispersion, the coefficient of variation is used as a band variation rate in this embodiment. CV is obtained from the following equation.
CV (%) = standard deviation / arithmetic mean × 100

Next, a method for obtaining a deviation rate (BWσ) which is a deviation between the NIC transmission rate standard value and the measured bottleneck physical bandwidth will be described. In the connection to the Internet in the recent wireless communication system, the transmission speed in the wireless portion, that is, the transmission speed of the NIC often becomes a bottleneck. For this reason, it is possible to estimate how much the measurement result has an error depending on the type of NIC by comparing the prescribed transmission rate of each NIC with the value of the measured bottleneck physical bandwidth. . Since the bottleneck physical bandwidth is measured as a unidirectional bandwidth, the upstream transmission speed of the NIC to be measured by the communication terminal 26 is X bps, and the downstream direction of the NIC to be measured by the communication partner terminal 27 is If the transmission rate is Ybps and the measured bottleneck physical bandwidth is BWT, the smaller value of X or Y is Z. BWσ (%) = | BWT−Z | / Z
As required.

The above measurement is performed on the transmission path list registered in the transmission path information table 21 (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, after completion of the simple measurement, the transmission path state management unit 23 writes the transmission path information based on the simple measurement result acquired by the above-described measurement method in the transmission path information table 21, and uses the acquired information as the transmission path information. A transmission path is selected from the table 21 and the application priority reference table 15 (S414, S415).

  FIG. 14 is a flowchart illustrating an example of a processing procedure for selecting a transmission path at the start of communication from the transmission path information table 21 and the application priority reference table 15. First, as shown in FIG. 14, it is confirmed whether or not a priority NIC item is specified in the application priority reference table 15 (S01). When the priority NIC is designated (S01 Yes), the transmission path information in the transmission path information table 21 is referred to confirm whether the designated priority NIC exists on the table and can be used (S02). If possible, the priority NIC is selected (Yes in S02).

  When the priority NIC item is not specified in the application priority standard table 15 (S01 No) or when the priority NIC is not usable (S02 No), the application priority standard table 15 indicates whether there is cross traffic. It is confirmed whether the flag is set (S03). If the flag indicating the presence / absence of cross traffic is set (S03 Yes), a transmission path without cross traffic is selected with reference to the transmission path information table 21 (S04). Further, when there are a plurality of transmission paths selected in the step (S04), it corresponds to the band fluctuation rate and the band deviation rate of the transmission path information table 21 and the respective items set in the application priority reference table 15. A value obtained by multiplying the weighting values to be compared is compared, and the transmission path having the smallest value is selected (S05).

  When the flag indicating the presence / absence of cross traffic is not set in the application priority reference table 15 (No in S03), referring to the transmission path information table 21, the fluctuation of the bandwidth of the transmission path information table 21 as described above The transmission line having the smallest value is selected by comparing the value obtained by multiplying the rate and the band deviation rate by the weighting value corresponding to each item set in the application priority reference table 15 (S05).

  3 and 4, when a transmission path is selected, the transmission path selection unit 19 refers to the transmission path information table 21 and notifies the application unit 11 of the transmission path information of the selected transmission path (S416). , S417). In the present embodiment, “(bottleneck physical bandwidth) ÷ (bandwidth variation rate)” obtained from the simple measurement result as the transmission path state 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 NIC transmission rate may be notified as they are. Further, RTT or a packet loss rate may be used as a result of the simple transmission path state measurement.

  The content control unit 14 refers to the quality information table 16 based on the notified transmission path information and determines the content quality in communication (S418, S419). The communication control unit 13 exchanges information for determining the type of video / audio and usage parameters according to the content quality determined by the content control unit 14 as described above with the communication partner, and then starts data transmission / reception (S435). At the same time, the IP control unit 20 switches to the transmission path selected by the transmission path selection unit 19 (S414, S415).

  At the same time, detailed measurement is performed in parallel with the above processing, and the transmission path state management unit 23 writes the transmission path information acquired by the measurement method described above into the transmission path information table 21 (S423, S424). The transmission path selection unit 19 selects a transmission path from the acquired transmission path information table 21 and the application priority reference table 15 (S425, S426).

FIG. 15A and FIG. 15B are flowcharts showing an example of a processing procedure for selecting a transmission path suitable for an application request from detailed measurement results based on information in the transmission path information table 21 and the application priority reference table 15. .
First, in the flowchart of FIG. 15A, it is confirmed whether or not a charge priority item is specified in the application priority reference table 15 (S06). In the present embodiment, it is assumed that a charge setting item is set to either free, a fixed amount system, or a pay-per-use system. When the free / flat rate system is designated as the priority for charge (S06 Yes), the free / flat rate transmission path is extracted with reference to both the network interface information table 22 and the transmission path information table 21 (S07).

  Furthermore, when the bandwidth priority is set in the application priority reference table 15 (S08 Yes), the transmission path with the largest bandwidth is selected from the extracted transmission paths (S09). If the bandwidth priority item is not set (S08 No), it is checked whether the delay priority item is set. If it is set (S10 Yes), the extracted transmission path is selected. The transmission path with the smallest delay amount is selected (S11). Furthermore, when the delay priority item is not set (No in S10), it is confirmed whether the extracted transmission path satisfies the required bandwidth or the required delay. If there is a transmission line that satisfies both conditions (S12 Yes, S13 Yes), the transmission line with the lowest bandwidth and the highest bandwidth is selected (S14).

  When the extracted transmission path cannot satisfy either the required bandwidth or the required delay (S12 No, S13 No), the process proceeds to the flowchart of FIG. Then, the transmission path is selected (S15 to S25). Also, when the charge priority is not set in the application priority reference table 15 (No in S06), the same processing procedure is performed to select a transmission path (S15 to S25).

  However, if neither bandwidth priority nor delay priority is set in the application priority reference table 15 (S15 No, S18 No), and there is no transmission path that satisfies the required bandwidth (S22 No), the user setting unit 12 It is notified that there is no transmission path that satisfies the requested bandwidth (S24), and the user is notified that the service cannot be provided. If the requested bandwidth can be satisfied (S22 Yes) but the requested delay cannot be satisfied (S23 No), the user setting unit 12 is notified that there is no transmission path that satisfies the requested delay (S25), and the user is notified. Will be notified that the service cannot be provided. If the required delay can be satisfied (S23 Yes), the flow returns to the flow of FIG. 15A, and the transmission path with the lowest bandwidth and the highest bandwidth is selected (S14).

  In addition, since uplink / downlink exists for the transmission path, in this embodiment, it is assumed that each of the own terminal and the communication partner terminal selects the downlink transmission path. In the case of server-client type one-way communication such as video streaming and audio streaming, a transmission path is selected on the client side. Not limited to this embodiment, each terminal may select an uplink transmission path instead of a downlink, or one terminal may perform processing so as to select either an uplink / downlink transmission path.

  Here, an example in which different transmission paths are selected for uplink / downlink will be described with reference to FIG. The own terminal 26 includes two NICs, FOMA and PHS, and the communication partner terminal 27 includes only a wireless LAN (IEEE 802.11b) NIC, and can be connected to the IP network via each NIC. To do. In this embodiment, FOMA is a pay-per-use billing system of 384 kbps and upstream 64 kbps, PHS is a flat-rate system upstream / downstream 64 kbps, and the wireless LAN is a flat-rate system and upstream / downstream 11 Mbps. In this case, the network interface information table 22 and the transmission path information table 21 of each NIC are as shown in FIGS. 17A and 17B, respectively.

  An example of the result of simple measurement is shown in FIG. Here, in the present embodiment, it is assumed that cross traffic is detected in the transmission path 1 and the transmission path 3, and provisional values are set for the band fluctuation rate and deviation rate. As a characteristic of the measurement method of bottleneck physical bandwidth by probe packet using packet pair transfer method and packet train transfer method, the fluctuation rate tends to be high when cross traffic exists, and due to the influence of cross traffic In the measurement with a small amount of probe packets, there is a high possibility that the measurement error will increase. Therefore, the value is set in consideration of such a tendency.

  As application priority criteria, there is no priority NIC, there is bandwidth priority, pay-as-you-go system for charges, the flag of presence / absence of cross traffic is OFF, and the bandwidth variation rate and deviation rate weighting values are 60 and 40, respectively. The priority standard table 15 is as shown in FIG. Here, as shown in FIG. 17C, in this embodiment, there are four transmission paths existing between the own terminal 26 and the communication partner terminal 27. First, when a transmission line is selected based on the simple measurement result, the weighting of each item is as shown in FIGS.

  Such calculation may be recalculated for only the transmission path whose communication status has changed, or may be recalculated for all transmission paths, and the priority of the transmission path is determined for each transmission path decision. To do. When the transmission path is selected according to the flowchart of FIG. 14, the priority NIC is not specified for the transmission path from the own terminal 26 to the communication partner terminal 27 (S01 No), the cross traffic presence / absence flag is OFF (S03 No), and transmission is performed. Since the calculated fluctuation rate and deviation of the band of the transmission line 2 are smaller than those of the line 1, the transmission line 2 is selected as the transmission line having the smallest value (S05).

  Similarly, as for the transmission path from the communication partner terminal 27 to the own terminal 26, the priority NIC is not specified in the flowchart of FIG. 14 (S01 No), and the cross traffic presence / absence flag is OFF (S03 No). Since the calculated fluctuation rate and deviation of the band of the transmission line 4 are smaller than those of the transmission line 3, the transmission line 4 is selected as the transmission line having the smallest value (S05). By notifying the application unit 11 of the transmission path state corresponding to the selected transmission path, data communication can be started without detailed transmission path measurement.

  Next, a method of selecting a transmission path based on the detailed measurement result will be described using the flowcharts of FIGS. 15A and 15B. For the transmission path from the own terminal 26 to the communication partner terminal 27, the cost: free / flat-rate system is not specified in the flow of FIG. 15A (S06 No), and the flow proceeds to the flow of FIG. 15B.

  In the flow of FIG. 15B, band priority is specified (S15 Yes), the bandwidths of the transmission path 1 and the transmission path 2 are the same, and there are transmission paths of the same band (S16 Yes), so the transmission with the lowest charge is performed. “Transmission path 2” is selected as the path (S20). Similarly, as for the transmission path from the communication partner terminal 27 to the own terminal 26, the cost: free / flat-rate system is not specified in the flowcharts of FIGS. 15A to 15B (No in S06), and bandwidth priority is specified. Since the bandwidth of the transmission path 3 is larger than that of the transmission path 4 (S16 No), “transmission path 3” is selected as the transmission path with the largest bandwidth (S17).

  If bandwidth priority is not specified (S15 No) and delay priority is set (S18 Yes), if a transmission path with the same delay exists (S19 Yes), the transmission path with the lowest charge is selected. (S20). If there is no transmission path with the same delay (No in S19), the transmission path with the smallest delay amount is selected (S21).

  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 19 does not select one transmission line, but rather assigns a relative priority to each transmission line (weights each item and assigns each transmission line based on the weighting). It is also possible to give points to the communication partner and to notify the communication partner of the priority, and to determine the transmission path.

  3 and 4, when a transmission path is selected, the transmission path selection unit 19 refers to the transmission path information table 21 and notifies the application unit 11 of the transmission path information of the selected transmission path (S431). , S432). In this embodiment, the application unit 11 is notified of the bandwidth (bottleneck physical bandwidth) that can be allocated to the application as the transmission path state in the same manner as when communication is started. Bandwidth occupies a major factor in determining the quality of application content. However, depending on the target content, information such as transmission path delay, usable bandwidth, and packet loss rate may be required. Therefore, you may notify any of those information collectively as needed.

  The content control unit 14 refers to the quality information table 16 based on the notified transmission path information and determines the content quality in communication (S433, S434). The communication control unit 13 exchanges information for determining the type of video / audio and usage parameters according to the content quality determined by the content control unit 14 as described above with the communication partner, and then starts data transmission / reception (S435). At the same time, the IP control unit 20 switches to the transmission line selected by the transmission line selection unit 19 (S429, S430).

  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 any medium that can be connected to the IP network, such as a wired LAN represented by Ethernet (registered trademark) as well as wireless.

  Next, when the communication terminal 10 performs data communication using an application or the like using communication such as video or audio, the own terminal 26 and the communication partner terminal 27 when the communication state of the transmission path surrounding the communication terminal changes. An example of the operation of each part will be described with reference to FIG.

  A user can move freely by taking advantage of wireless. 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 18 is notified that the NIC state has changed (S517), and the notified value is written in the corresponding part of the network interface information table 22 (the link state flag is rewritten from “0” to “1”). (S501).

  The transmission path management unit 18 notifies the communication partner terminal 27 of the information of the corresponding newly usable network interface (S518). An example of the network interface information notified here is shown in FIG. Here, in the case of the embodiment at the start of communication (three NICs that can be used by the own terminal (NICs 1 to 3) and two NICs that can be used by the communication partner terminal (NICs 4 to 5)), the own terminal 26 When the NIC 6 becomes usable, the IP address corresponding to the added NIC name NIC 6 is transmitted.

  When there are a plurality of added network interfaces, a list of IP addresses corresponding to NIC names is transmitted. Here, the IP address may be an IPv4 address or an IPv6 address. Further, the list may be transmitted not only to the added network interface but also to all the network interfaces that can communicate. The communication partner terminal 27 creates a transmission path list added between the own terminal 26 and the communication partner terminal 27 based on the received network interface information and the network interface information table 22 in its own terminal.

  In the case of all network interface lists in which the transmitted network interface information can be communicated, a transmission path list existing between the own terminal 26 and the communication partner terminal 27 is created. An example of the added transmission path list is shown in FIG. The created transmission path list is notified from the communication partner terminal 27 to the own terminal 26, registered in each transmission path information table 21 (S503, S504), and notified to each transmission path status management unit 23 ( S519, S520).

  The transmission line state management unit 23 measures the transmission line state of the added transmission line based on the notified information (S521). For the explanation and measurement method of each item, the same method as described in the embodiment at the start of communication is used. From the transmission path information thus obtained and the application priority criteria, the transmission path is determined according to the flowcharts of FIGS. 14 to 15B (S507, S508). When the determined transmission path is different from the currently used transmission path (S509 Yes, S510 Yes), the transmission path selection unit 19 refers to the transmission path information table 21 and obtains the transmission path information of the selected transmission path. The application unit 11 is notified (S522, S523).

  In the present embodiment, the bandwidth that can be allocated to the application is notified to the application section 11 as the transmission path state in the same manner as the embodiment at the start of communication. The content control unit 14 refers to the quality information table 16 based on the notified transmission path information and determines the content quality in communication. If it is determined that content switching is necessary (S513 Yes, S514 Yes), the 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 (S524), data transmission / reception is started with the switched content quality (S515, S516), and at the same time, the IP control unit 20 switches to the transmission path selected by the transmission path selection unit 19 (S511, S512). .

  If the selected transmission line matches the currently used transmission line, nothing is done. In addition, when the selected transmission path is different from the currently used transmission path and the content control unit 14 determines that there is no need to switch the contents (No in S513 and S514), only the transmission path is switched ( S511, S512).

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

  As described above, while the communication terminal 10 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 as a result of changes in the wireless environment. In some cases, the communication terminal 10 exists by reselecting the transmission path information according to the transmission path information between the communication terminals, the application priority standard, and the user's preference, and notifying the application of information based on the transmission path. It becomes possible to provide a quality service according to the wireless environment and network conditions of the place. The transmission path may be any medium that can be connected to the IP network, such as a wired LAN represented by Ethernet (registered trademark) as well as wireless.

  Next, when the communication terminal 10 performs data communication using an application or the like using communication such as video or audio, the own terminal 26 and the communication partner terminal 27 when the communication state of the transmission path surrounding the communication terminal changes. Another example of the operation of each part will be described with reference to FIG.

  A user can move freely by taking advantage of wireless. Here, during movement, for example, the network interface management unit 24 decreases the radio field strength of the currently communicating network interface (link status flag “1”), changes from Level 4 to Level 2, and the threshold value changes to Level 3. If it has been set, the network interface that was available becomes unusable. The transmission path management unit 18 is notified that the state of the network interface has changed (S517), and the notified value is written in the corresponding part of the network interface information table 22 (the link state flag is rewritten from “1” to “0”). (S501).

  The transmission path management unit 18 notifies the communication partner of information on the corresponding network interface that has become unusable (for example, a network interface name) (S518), and simultaneously transmits the information on the corresponding transmission path from the transmission path information table 21. Delete (S503). Similarly, the communication partner terminal 27 deletes the information of the corresponding transmission path from the transmission path information table 21 held in the communication partner terminal 27 based on the notified network interface information (S504).

  The transmission path management unit 18 determines a transmission path from the updated transmission path information and application priority standards according to the flowcharts of FIGS. 14 to 15B (S507, S508). Here, the transmission path state management unit 23 re-transmits the transmission path based on the updated transmission path information table 21 (for the transmission path after deleting the transmission path corresponding to the network interface whose state has changed). You may measure a state (S519-S521, S505, S506). When a transmission path to be newly used is determined, the transmission path selection unit 19 refers to the transmission path information table 21 and notifies the application unit 11 of transmission path information on the selected transmission path (S522, S523).

  In the present embodiment, the bandwidth that can be allocated to the application is notified to the application section 11 as the transmission path state in the same manner as the embodiment at the start of communication. The content control unit 14 refers to the quality information table 16 from the notified transmission path information, determines the content quality in communication, and determines that the content needs to be switched (S513 Yes, S514 Yes), the content After exchanging information for determining the type of video / audio and usage parameters with the communication partner in accordance with the content quality determined by the control unit 14 (S524), data transmission / reception is started, and at the same time, the IP control unit 20 transmits the transmission path. Switching to the transmission path selected by the selector 19 is performed (S511, S512). If the content control unit 14 determines that there is no need to switch the content (S513 No, S514 No), only the transmission path is switched (S511, S512).

  In this embodiment, the control when the radio field strength of the network interface currently in use is weakened has been described. However, when the radio field strength of the network interface that is not currently used and the network interface is currently usable is weakened. Also, the communication partner terminal 27 may be notified of information on the corresponding network interface that has become unusable. The same processing is performed for the control procedure of deleting the information in the corresponding transmission path information table 21 by the own terminal 26 and the communication partner terminal 27, and in this case, the only difference is that the transmission path is not selected.

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

  As described above, while the communication terminal 10 is performing data communication with an application using communication such as video and audio through the wireless environment, the transmission path currently being used is triggered by the change in the state of the wireless environment. Even when the state changes, it is possible to reselect the transmission path according to the transmission path information between the communication terminals, the priority standard of the application, and the user's preference. By notifying the application of information based on the transmission path, it is possible to provide a quality service according to the wireless environment and the network status of the place where the communication terminal 10 exists. The transmission path may be any medium that can be connected to the IP network, such as a wired LAN represented by Ethernet (registered trademark) as well as wireless.

  Next, when the communication terminal 10 performs data communication using an application or the like using communication such as video or audio, the own terminal 26 and the communication partner terminal 27 when the communication state of the transmission path surrounding the communication terminal changes. Another example of the operation of each part will be described with reference to FIG.

  A user can move freely by taking advantage of wireless. Here, during movement, the network interface management unit 24 changes the physical link speed of the wireless communication of the currently communicating network interface (change in physical transmission speed in IEEE802.11b from 11 Mbps to 5.5 Mbps, FOMA, etc. Assume that a change in bearer transmission speed at 384 kbps to 64 kbps is detected. The transmission path management unit 18 is notified that the NIC state has changed (S517), and the value (transmission rate of 11 Mbps to 5.5 Mbps or 384 kbps to 64 kbps, etc.) is written to the corresponding part of the network interface information table 22. (S501).

  The transmission path management unit 18 notifies the communication partner terminal 27 of the information of the network interface whose communication state has changed (S518). Here, an example of the notified network interface information is shown in FIG. Here, in the embodiment at the start of communication, NIC1 is an IEEE802.11b network interface, and the update part of the network interface information table 22 indicates that the transmission speed of NIC1 of its own terminal 26 has changed from 11 Mbps to 5.5 Mbps. Only information is transmitted (S518). When there are a plurality of network interfaces whose communication states have changed, a list of information on the updated portion of the network interface information table 22 corresponding to the NIC name is transmitted. Further, not only the updated part but also a list of all network interfaces that can communicate may be transmitted.

  The communication partner terminal 27 updates the network interface information table 22 in its own terminal based on the received network interface information, and the transmission line state management unit 23 measures the transmission line state of the corresponding transmission line ( S521). Here, only the transmission line state of the transmission line corresponding to the updated network interface is measured again, but the transmission line state may be measured again for all transmission lines. For the explanation and measurement method of each item, the same method as described in the embodiment at the start of communication is used. From the transmission path information thus obtained and the application priority criteria, the transmission path is determined according to the flowcharts of FIGS. 14 to 15B (S507, S508).

  When the determined transmission path is different from the currently used transmission path (S509 Yes, S510 Yes), the transmission path selection unit 19 refers to the transmission path information table 21 and obtains the transmission path information of the selected transmission path. The application unit 11 is notified (S522, S523). In the present embodiment, the bandwidth that can be allocated to the application is notified to the application section 11 as the transmission path state in the same manner as the embodiment at the start of communication.

  The content control unit 14 refers to the quality information table 16 based on the notified transmission path information and determines the content quality in communication. If it is determined that content switching is necessary (S513 Yes, S514 Yes), the communication control unit 13 exchanges information for determining the video / audio type and usage parameters according to the determined content quality with the communication partner. (S524), data transmission / reception is started with the switched content quality (S515, S516). At the same time, the IP control unit 20 switches to the transmission path selected by the transmission path selection unit 19 (S511, S512). If the selected transmission line matches the currently used transmission line, nothing is done. In addition, when the selected transmission path is different from the currently used transmission path and the content control unit 14 determines that there is no need to switch the contents (No in S513 and S514), only the transmission path is switched ( S511, S512).

  In the present embodiment, the case where the physical link speed of the wireless communication of the network interface is changed has been described. However, when it is detected that the wireless modulation method is changed (the modulation method in IEEE 802.11b is changed from QPSK to BPSK). With regard to (change), it is possible to provide a quality service according to the communication environment by performing control according to the processing procedure described in this embodiment.

  Next, when the communication terminal 10 performs data communication by an application using communication such as video or audio, any or all of the transmission paths existing between the communication terminals are diffserve. A processing operation for selecting a transmission path when QoS such as RSVP (Resource Reservation Protocol) is supported will be described. FIG. 20 is a flowchart showing an example of a processing procedure for selecting a transmission path at the start of communication from the transmission path information table 21 and the application priority reference table 15, and FIG. 21A shows the application priority reference table 15 and FIG. Is another example of the transmission path information table 21.

  First, as shown in FIG. 20, it is confirmed whether or not QoS support is required / not required in the application priority standard table 15 (S26). If QoS support is necessary (S26 Yes), the transmission path information in the transmission path information table 21 is referred to extract a transmission path that supports QoS (S27). Here, it is confirmed whether or not a transmission path that supports QoS exists in the transmission path information table 21 (S28). If it exists (S28 Yes), it is further checked whether or not bandwidth priority is set in the application priority reference table 15 (S29). The following processing is the same as that described in the flowchart of FIG. 15A.

If a transmission path that supports QoS is not included in the transmission path information table (No in S28), the process proceeds to the flowchart of FIG. 15B as in the case where either the required bandwidth or the required delay cannot be satisfied (S33 No, S34 No). Then, the processing shown in FIG. 15B is performed on the transmission path that does not support QoS, and the transmission path is selected (S15 to S25).
Since uplink / downlink exists for the transmission path, in this embodiment, each of the own terminal and the communication partner terminal selects the downlink transmission path. In the case of server-client type one-way communication such as video streaming and audio streaming, a transmission path is selected on the client side. Not limited to this embodiment, each terminal may select an uplink transmission path instead of a downlink, or one terminal may perform processing so as to select either an uplink / downlink transmission path.

  In this embodiment, an example of the processing procedure for selecting a transmission path at the start of communication has been described with reference to the flowcharts of FIGS. 20 and 15B. Even when the communication state of the transmission path surrounding the communication terminal changes during communication, it is possible to select the transmission path according to the user's wireless environment by following the processing procedure described above. Become.

  In this embodiment, a protocol such as Diffserve or RSVP is cited as an example of a transmission path that supports QoS. However, in the case of circuit switched connection such as FOMA or PHS that guarantees line quality, or IEEE802.11e When a network interface that supports QoS in such a wireless section is included in the transmission path, the QoS support item in the transmission path information table 21 may be set to “supported”. Such information can be determined from the network interface information table 22.

  As mentioned above, although the example in the case where the communication state has changed in the own terminal has been described in the above embodiment, the transmission path selection and It becomes possible to provide a quality service according to the user's communication status such as application linkage.

[0001]
Technical field [0001]
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 terminals.
Background art [0002]
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. Also, mobile terminals are becoming more sophisticated, and one terminal device can be connected to multiple networks (for example, a wireless LAN (Local Area Network), 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.
[0003]
In addition, with the advent of technologies (Mobile IPv6, Lin6, etc.) that enable continuous wireless communication between different networks, services are seamlessly selected when communication is switched by selecting the optimal communication environment each time it is used. It is becoming possible to receive. 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).
[0004]
On the other hand, data communication while moving wirelessly is unstable or unstable when the radio wave intensity changes with the movement, communication is interrupted, or when moving to a different wireless network. Therefore, a method has been proposed in which network switching control and data quality control are performed by providing means for notifying the upper layer of such lower layer information (see Patent Document 2).
[0005]
It is also possible to estimate the end-to-end bandwidth, available bandwidth, and usage between communication terminals. For example, for each router on the route, ICMP (Internet Control)

[0003]
It is also necessary to select different transmission paths for downstream use.
[0009]
Further, in the technique disclosed in Patent Document 3, in order to estimate the end-to-end transmission path state, it is necessary to transmit a large number of probe packets and to statistically process the result. It takes a lot of time to estimate the 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.
The present invention provides a communication system and a communication terminal for efficiently solving the various problems described above.
Means for Solving the Problems [0010]
The communication system of the present invention is a communication system in which a communication terminal having a network interface connectable to a plurality of transmission paths uses a plurality of transmission paths, and the communication terminals can communicate with each other among a plurality of network interfaces. Detects the interface, obtains network interface information related to predetermined attributes of a plurality of network interfaces, creates a transmission path list existing between the communicable network interface and the communicable network interface of the communication partner, and Associate interface information with the transmission path list, and acquire at least one of bottleneck physical bandwidth, cross traffic, bandwidth fluctuation rate, and bandwidth deviation rate as transmission path information related to the transmission path status corresponding to the transmission path list And transmission Priority is determined based on transmission path information and a priority standard set for each application program that performs data communication, a transmission path is determined, and data communication is performed via the determined transmission path. . In addition, when a combination of transmission paths is selected from the transmission path list, the information from the communication terminal on the transmission side is designated as the destination of one of the network interfaces of the partner communication terminal, and the communication terminal on the transmission side is specified. Data communication using the selected transmission path is performed by transmitting any one of the network interfaces to the transmission path as a transmission source.
[0011]
The bottleneck physical bandwidth is obtained by closely transmitting a probe packet of the same size S from the transmission terminal to the reception terminal, receiving the probe packet at the reception terminal, and measuring the bottle interval from the measured probe packet reception interval ΔT. Neck physical bandwidth B = B / S / ΔT
Calculate based on
Further, in the means for obtaining the bottleneck physical bandwidth, the pair of size S

[0005]
When the status of the transmission line, the transmission line state of the transmission line being used, the wireless modulation method, etc. change, the priority of the transmission line is judged again and the transmission line with the highest priority is switched.
Effect of the Invention [0015]
According to the present invention, in a communication system between communication terminals including a mobile terminal having a plurality of network interfaces in a communication environment that changes every moment as a user moves, data communication is performed by an application using communication such as video and audio. When performing the transmission, it is possible to select a transmission path according to the priority criteria set for each application or the user's preference. At the same time, it is possible to provide a quality service according to the location where the communication terminal exists by selecting content of quality matching the network information.
[0016]
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, the state of the transmission line is acquired again due to a change in the communication state of the transmission line, and the transmission line is selected again according to the priority standard or user preference set for each application. Thus, even in a communication environment that changes from moment to moment, it is possible to provide a service with a quality that is optimal for the communication environment where the communication terminal exists.
BRIEF DESCRIPTION OF THE DRAWINGS [0017]
FIG. 1 is a diagram showing an example of the overall configuration of a network to which this embodiment can be applied.
FIG. 2 is a conceptual diagram of an accessible area corresponding to a base station of a wireless network to which this embodiment can be applied.
FIG. 3 is a functional block diagram showing an internal configuration example of a communication terminal according to the present invention.
FIG. 4 is an operation sequence diagram showing the operation of each unit at the start of communication of the communication terminal 10.
FIG. 5 is a sequence diagram showing the operation of each part when the communication state of the network interface card of the communication terminal 10 changes.
FIG. 6 is a diagram showing an example of a network interface information table in the present embodiment.
[FIG. 7] An example of a communication information notification format (A) in this embodiment, a quality information table

Claims (23)

A communication terminal having a network interface connectable to a plurality of transmission paths is a wireless communication system using a plurality of transmission paths,
Means for detecting a communicable network interface among the plurality of network interfaces;
Means for obtaining network interface information relating to predetermined attributes of the plurality of network interfaces;
Means for creating a transmission path list existing between the communicable network interface and the communicable network interface of the communication partner;
Means for associating the network interface information with the transmission path list;
Means for acquiring at least one of a bottleneck physical bandwidth, cross traffic, a bandwidth variation rate, and a bandwidth deviation rate as transmission route information relating to the state of the transmission route corresponding to the transmission route list;
Means for determining the priority of the transmission path based on priority criteria set for each application program for performing the transmission path information and data communication, and determining a transmission path,
A wireless communication system, wherein data communication is performed via the determined transmission path. The bottleneck physical bandwidth is obtained by closely transmitting a probe packet of the same size S from the transmission terminal to the reception terminal, receiving the probe packet at the reception terminal, and measuring the bottle interval from the measured probe packet reception interval ΔT. Neck physical bandwidth B is B = S / ΔT
The wireless communication system according to claim 1, wherein the wireless communication system is calculated based on   In the means for obtaining the bottleneck physical bandwidth, a pair of probe packets of size S and a pair of packets of size S ′ smaller than size S are transmitted as probe packets and measured by the receiving terminal. When the delay time of the probe packet of size S is ΔT ′, the delay time of the probe packet of size S ′ is ΔT ″, and ΔT ″> ΔT ′, it is determined that cross traffic exists. Item 3. The wireless communication system according to Item 2. When n measurement results are obtained from the means for obtaining the bottleneck physical bandwidth, the band variation rate CV is calculated from the standard deviation and the arithmetic mean of the obtained measurement results. CV = standard deviation / arithmetic mean × 100
The wireless communication system according to claim 2, wherein the wireless communication system is calculated based on When the bottleneck bandwidth obtained from the means for obtaining the bottleneck physical bandwidth is BWT, the transmission path speed in the uplink direction of the network interface on the transmission side of the transmission path and the network interface on the reception side are measured. Assuming that the smaller value of the transmission rates in the downstream direction is Z, the band deviation rate BWσ is BWσ (%) = | BWT−Z | / Z
The wireless communication system according to any one of claims 2 to 4, wherein the wireless communication system is calculated based on:   The wireless 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.   The wireless communication system according to claim 1, wherein the transmission path information includes an RTT (Round Trip Time) delay difference between a transmission path to which the plurality of network interfaces are connected and a communication partner.   The wireless 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.   2. The transmission path information includes a flag indicating whether or not a transmission path between the transmission path connected to the plurality of network interfaces and a communication partner supports QoS (Quality of Service). The wireless communication system according to 1.   The wireless communication system according to claim 1, wherein the network interface information includes a communication status detected in a layer lower than a transport layer.   The wireless communication system according to claim 10, wherein the network interface information includes a network interface transmission rate.   The wireless communication system according to claim 11, wherein when the network interface transmission rate is different between uplink and downlink, each is acquired as different information.   The wireless communication system according to claim 1, wherein the priority of the transmission path is determined every time a transmission path is determined.   The wireless communication system according to claim 1, wherein the priority of the transmission path is determined based on a priority standard set for each application program that performs data communication.   15. The wireless communication system according to claim 14, wherein, in the case of an asymmetric communication network having different uplink / downlink channel characteristics, different uplink / downlink channel can be selected according to the priority criteria.   The wireless communication system according to claim 13, wherein when the required bandwidth is used as a priority criterion, a plurality of the required bandwidths are set for each application program.   The data type of the data communication comprises means for determining the quality of the content from the quality information set for each application program and the transmission path information regarding the determined transmission path by referring to the information. The wireless communication system according to claim 13. Means for detecting a change in the state of a network interface that is not in data communication after the start of data communication;
Means for obtaining network interface information relating to predetermined attributes of the plurality of network interfaces;
Again, create a transmission path list that exists between the communicable network interface and the communication partner's communicable network interface, and associate the network interface information with the transmission path list,
Acquire at least one of bottleneck physical bandwidth, cross traffic, bandwidth fluctuation rate, bandwidth deviation rate as transmission path information related to the status of the transmission path corresponding to the newly created transmission path list,
Judging the priority of the transmission path based on the transmission path information and priority criteria set for each application program that performs data communication, determine the transmission path,
The wireless communication system according to any one of claims 1 to 17, wherein when the determined transmission path is different from a transmission path in communication, the transmission 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. 19. The wireless communication system according to claim 18, further comprising means for performing data communication based on the data communication.   The transmission path status of the transmission path being used is monitored and compared with an arbitrary threshold value, so that the priority of the transmission path is determined again, and the transmission path with the highest priority is determined. The wireless communication system according to claim 18.   19. The wireless communication system according to claim 18, wherein the wireless communication system detects that the wireless modulation system has changed, determines the priority of the transmission path again, and determines the transmission path with the highest priority. A communication terminal having a network interface connectable to a plurality of transmission paths is a wireless communication method using a plurality of transmission paths,
Detecting a network interface capable of communication among the plurality of network interfaces;
Obtaining network interface information relating to predetermined attributes of the plurality of network interfaces;
Create a transmission path list that exists between the communicable network interface and a communication partner's communicable network interface, and associate the network interface information with the transmission path list,
Obtain at least one of bottleneck physical bandwidth, cross traffic, bandwidth fluctuation rate, bandwidth deviation rate as transmission path information related to the status of the transmission path corresponding to the transmission path list,
Judging the priority of the transmission path based on the transmission path information and priority criteria set for each application program that performs data communication, determine the transmission path,
A wireless communication method comprising performing data communication via the determined transmission path. After data communication starts, it detects that the status of the network interface that is not in data communication has changed,
Obtaining network interface information relating to predetermined attributes of the plurality of network interfaces;
Again, create a transmission path list that exists between the communicable network interface and the communication partner's communicable network interface, and associate the network interface information with the transmission path list,
Acquire at least one of bottleneck physical bandwidth, cross traffic, bandwidth fluctuation rate, bandwidth deviation rate as transmission path information related to the status of the transmission path corresponding to the newly created transmission path list,
Judging the priority of the transmission path based on the transmission path information and priority criteria set for each application program that performs data communication, determine the transmission path,
23. The wireless communication method according to claim 22, wherein when the determined transmission path is different from a transmission path in communication, the transmission path is switched to a newly determined transmission path.

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