JP6488528B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, COMMUNICATION PROGRAM, AND PROCESSOR - Google Patents

Description

  The present invention relates to a communication device, a communication method, a communication program, and a processor.

  In wireless communication, when the quality of a certain radio link is reduced, a technique for detecting a quality drop and switching to a different radio link has been known (for example, Patent Documents 1 and 2 and Non-Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 2005-223811 JP 2007-336335 A

“Wireless Japan 2012: Effective speed more than double -KDDI's“ Link Aggregation Wireless Technology ”” [online], May 30, 2012, ITmedia + D Mobile, [Search November 13, 2014], Internet (URL: http://plusd.itmedia.co.jp/mobile/articles/1205/30/news066.html) Takayuki WARABINO and others, Proposal of a device handoff methods for seamless communications, IPSJ SIG Technical Reports Vol.2003 No. 114 IPSJ SIG Technical Reports, Japan, Japan Information Processing Society of Japan, Information Processing Society of Japan, November 14, 2003, Vol. 2003, pp. 105-112

For example, in the technique described in Patent Document 1, a means for using the link 2 from the middle of communication is proposed for the case where the link 1 is disconnected in the fallback operation. It does not describe the means for confirming connectivity.
For example, in TCP (Transmission Control Protocol) communication, it is considered that the connection of the communication path is completed with a response to the connection request. Therefore, if there is no response to the connection request for a predetermined time, it is considered that the logical connection is not established in the corresponding communication route, and a route control method using another communication route is generally performed. .
However, in the above-described case, when the communication path is switched by the path control, the subsequent communication is generally performed on the communication path after switching. In this case, there is a possibility that the communication terminal switches the communication path even when a response to the connection request is delayed when making a connection to a certain server. In addition, when the threshold value of the response delay amount set as the determination condition for switching the communication path is not an appropriate delay amount with respect to the network to which the communication terminal belongs, the communication terminal always switches the communication path. May not be able to use the communication path.

  The present invention has been made in view of the above points, and provides a communication device, a communication method, a communication program, and a processor that can appropriately control switching of a radio link.

SUMMARY An advantage of some aspects of the invention is that a first communication unit that performs first communication, a second communication unit that performs second communication, and the first communication. Whether or not the condition for switching from the second communication to the second communication is satisfied is determined for each predetermined series of communication, and from the first communication to the second communication for each series of communication based on the determination result And a selection unit that counts the number of the series of communications that are switched from the first communication to the second communication. The selection unit prioritizes the first communication. , when the number of the series of communications which the counting unit has counted exceeds the threshold, priority is given to the second communication for subsequent of the series of communications, a communication apparatus.

  Further, according to one aspect of the present invention, in the communication apparatus, the selection unit determines that the switching condition is satisfied when a response to the connection request using the first communication cannot be acquired for a predetermined time or more. .

  Further, according to one aspect of the present invention, in the communication device, when the selection unit has failed to acquire information capable of identifying a transmission source of communication data acquired using the first communication for a predetermined time or more, It is determined that the switching condition is satisfied.

  Further, according to one aspect of the present invention, in the communication device, the selection unit changes the predetermined time according to the number of switching from the first communication to the second communication.

  According to another aspect of the present invention, in the communication apparatus, the selection unit increases the predetermined time according to the number of switching from the first communication to the second communication.

  According to another aspect of the present invention, in the communication device, the selection unit linearly increases the predetermined time according to the number of switching from the first communication to the second communication.

  According to another aspect of the present invention, in the communication device, the selection unit increases the predetermined time in a non-linear manner according to the number of switching from the first communication to the second communication.

  In addition, according to an aspect of the present invention, in the communication device, the first communication and the second communication have different logical or physical communication interfaces, and the selection unit includes the first communication interface. The switching to the interface of the second communication is controlled.

According to another aspect of the present invention, in the communication method in the communication apparatus, the determination unit determines, for each predetermined series of communication, whether or not the selection unit satisfies a switching condition from the first communication to the second communication. A selection process for controlling switching from the first communication to the second communication for each of the series of communication based on a determination result of the determination and the determination, and a counting unit includes the second communication from the first communication to the second communication possess a counting step of counting the number of said series of communications is switched to the communication, a, in the selection process, the first priority communication, the number of the series of communications that are counted in the counting process threshold If it exceeds, the priority of the second communication for subsequent of the series of communications, a communication method.

According to another aspect of the present invention, there is provided a determination procedure for determining, for each predetermined series of communications, whether or not the computer of the communication device satisfies a switching condition from the first communication to the second communication. Based on the determination result, for each series of communications, a selection procedure for controlling switching from the first communications to the second communications, and the series of communications being switched from the first communications to the second communications. And in the selection procedure, the first communication is prioritized. When the number of the series of communications counted in the counting procedure exceeds a threshold, the subsequent procedure is performed. Preferred said second communication for a set of communication, a communication program.

In addition, according to one aspect of the present invention, it is determined for each predetermined series of communication whether or not the condition for switching from the first communication to the second communication is satisfied, and for each series of communication based on the determination result. includes a selecting unit for controlling the switching to the second communication from the first communication, and a counting section for counting the number of the series of communications from the first communication is switched to the second communication, the said The selection unit gives priority to the first communication, and when the number of the series of communications counted by the counting unit exceeds a threshold, the second communication is given priority over the series of subsequent communications. it is a processor.

  According to the present invention, switching of radio links can be appropriately controlled.

It is the schematic which shows the structure of the communication system which concerns on 1st Embodiment of this invention. It is a schematic block diagram which shows the structure of the communication apparatus which concerns on this embodiment. It is a schematic block diagram which shows the structure of the proxy part which concerns on this embodiment. It is explanatory drawing for demonstrating the fallback which concerns on this embodiment. It is explanatory drawing for demonstrating the failback which concerns on this embodiment. It is a figure showing the state transition of the communication apparatus which concerns on this embodiment. It is explanatory drawing about the state transition of the communication apparatus which concerns on this embodiment. It is a figure which shows the processing flow of the communication apparatus which concerns on this embodiment. It is a figure which shows the processing flow of the proxy part which concerns on this embodiment. It is a figure which shows the processing flow of the proxy part which concerns on this embodiment. It is another figure which shows the processing flow of the proxy part which concerns on this embodiment. It is another figure which shows the processing flow of the proxy part which concerns on this embodiment. It is another figure which shows the processing flow of the proxy part which concerns on this embodiment. It is another figure which shows the processing flow of the proxy part which concerns on this embodiment.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the configuration of a communication system according to the first embodiment of the present invention. In this figure, the communication system includes a communication device 1, an access point AP1, a base station device BS1, and server devices Sv101 to Sv104.

  The communication device 1 is a device capable of performing a plurality of different communications such as Wi-Fi (registered trademark, the same applies hereinafter), 3G (3rd Generation: third generation mobile communication system), LTE (Long Term Evolution), and the like. It is. The communication device 1 can bundle a plurality of physical links and handle them as one logical link (link aggregation). The communication device 1 is, for example, a smartphone, a tablet terminal, a feature phone, a personal computer, a mobile router, or the like.

The access point AP1 is a device that accepts a connection request from the communication device 1 and mediates communication to the network. For example, the access point AP1 is a wireless LAN access point, and can perform communication with the communication device 1 by Wi-Fi (referred to as a wireless link L1 and also referred to as Wi-Fi communication).
Base station apparatus BS1 is an apparatus that directly transmits and receives radio waves to and from a mobile phone. The base station apparatus BS1 can perform communication (referred to as a radio link L2) with the communication apparatus 1 by 3G or LTE. The base station device BS1 is connected to the mobile phone network N1, and can communicate with devices connected to the network N2 via the mobile phone network N1. For example, the network N2 is the Internet and has a communication protocol different from that of the cellular phone network N1.

  The server device Sv101 is, for example, a gateway server, and performs communication protocol conversion between the mobile phone network N1 and the network N2. The server device Sv102 is connected to the network N1, and can communicate with the communication device 1 via the base station device BS1. The server devices Sv103 and Sv104 are connected to the network N2, and can communicate with the communication device 1 via the access point AP1 or the mobile phone network N1 and the base station device BS1. For example, the server devices Sv102 and Sv103 are domain name system (DNS) server devices (also referred to as DNS servers) and manage domain name information in which host names and domain names on the network are associated with IP addresses. . For example, the server device Sv104 is a content server and performs communication (referred to as HTTP communication) of a protocol such as HTTP (Hypertext Transfer Protocol). The server device Sv104 provides, for example, content in HTML format to the communication device 1.

  When performing HTTP communication using the wireless link L1, the communication device 1 acquires and stores HTTP header information H1. After that, for example, when it is detected that the quality of the wireless link L1 has deteriorated, the communication device 1 makes an HTTP range request using the wireless link L2. A range request is a command that specifies a data range and requests only a portion of the data. Specifically, the communication device 1 can request and acquire (download) data after 501 bytes by designating “Range: bytes = 501-” in the header field of HTTP.

The communication device 1 performs a header comparison process that compares the header information H1 acquired using the wireless link L1 and the header information H2 acquired using the wireless link L2. In the header comparison process, for example, the communication device 1 compares information (information such as Content-Length) that can be determined to have a difference in the HTTP data portion (also referred to as body information) in the header information. As a result of the header comparison process, when it is determined that the header information H1 and the header information H2 are the same, the communication device 1 performs switching (referred to as fallback) from the wireless link L1 to the wireless link L2. Note that the communication device 1 changes the communication interface when performing fallback. As a result, the communication device 1 changes, for example, the IP address and port number used for communication. Note that fallback is not limited to changing the communication type, such as Wi-Fi and LTE, and may be performed between Wi-Fi communications. That is, for example, when there are two or more Wi-Fi communication interfaces, fallback includes changing the interface while maintaining Wi-Fi communication. The interface is not limited to a physical interface but may be a logical interface. The logical interface is, for example, an interface in VPN (Virtual Private Network).
On the other hand, if it is determined as a result of the header comparison processing that the header information H1 and the header information H2 are not all or partly the same, that is, if there is a difference in the HTTP data part, the communication device 1 stops the fallback. . Thereby, the communication apparatus 1 can acquire the continuation of the same content as before fallback using the wireless link L1 even when different content is returned for each access, for example. That is, the communication device 1 can prevent data inconsistency by combining data acquired using the wireless link L1 and data acquired using the wireless link L2 by fallback.

  If it is determined as a result of the header comparison process that the header information H1 and the header information H2 are not the same, the communication device 1 may try fallback again according to the header information acquired using the wireless link L2. Good. For example, when the status code indicates redirection in the header information H2 acquired using the wireless link L2, the communication device 1 makes an HTTP range request to the redirection destination again. Here, the case where the status code indicates redirection is, for example, a case where the destination URL is attached to the status code. Specifically, the status code at that time is “302” (Moved Permanently), “303” (Found), “307” (Temporary Redirect), or the like.

  As a result of the range request, the communication apparatus 1 acquires header information H2 'from the redirect destination (also referred to as RD destination information acquisition processing). The communication device 1 performs a header comparison process using the acquired header information H2 ', and performs a fallback when determining that the header information H1 and the header information H2' are the same. On the other hand, if the communication device 1 determines that the header information H1 and the header information H2 'are not the same, the communication device 1 stops the fallback.

  Further, for example, the communication device 1 determines whether or not to perform fallback for each session for each request from the application. One session fallback (FB) is also referred to as single fallback. The communication apparatus 1 counts the number of single fallbacks (the number of FB sessions to be described later), and determines that the radio link L1 is “communication impossible” when the predetermined allowable number is exceeded (the radio link L1 in this case) Is also referred to as an unnecessary link). In this case, when there is a communication request from an application, the communication device 1 makes a transition to a “forced fallback mode” state in which communication is performed using the wireless link L2.

As described above, the communication device 1 confirms whether the contents are the same by comparing the contents of the header information at the time of fallback, and transmits unexpected data (unupdated data, etc.) to the application. Can be prevented in advance.
Further, even when the communication apparatus 1 is redirected at the time of fallback, the communication apparatus 1 can perform the fallback when the same header information can be obtained, that is, when the content is finally the same.
By switching to the “forced fallback mode”, the communication device 1 eliminates the cost of trying to establish communication with an unnecessary link, and can immediately perform good communication. Note that the communication device 1 may perform a header comparison process when it is desired to restore the connection to the wireless link L1 that is determined to be an unnecessary link, thereby efficiently starting reuse.

  Further, the communication device 1 controls whether or not a single fallback is performed for each session, so that when a specific server or communication path is down or when a single fallback is performed in a specific network. In an environment in which a response delay equal to or greater than the threshold value to be determined occurs, it is possible to suppress switching to all other communications (communication with a possibility of successful connection) only by connection of a certain session. For example, the communication device 1 can calculate a response delay amount suitable for the system being used, and set the threshold as a threshold for determining whether to perform fallback.

  The communication device 1 controls whether or not a single fallback is performed for each session (whether or not a communication session can be established). However, if there is a single session that performs a single fallback, The threshold value for determining single fallback is weighted using the current number of single fallback sessions, and the number of single fallback sessions is two instead of two. You may adjust so that it may become difficult to fall back gradually. For example, when the communication device 1 determines that the fallback is performed when there is no response to the connection request for a predetermined time (for example, when the session times out), the communication device 1 determines this according to the number of sessions that are single fallback. Gradually increase the predetermined time.

<About the communication device 1>
FIG. 2 is a schematic block diagram illustrating a configuration of the communication device 1 according to the present embodiment. The communication device 1 includes an input unit 11, an output unit 12, a control unit 13, a storage unit 14, and a communication unit 15. The control unit 13 includes an application unit 131 and a proxy unit P1. The communication unit 15 includes N interfaces 151-1 to 151-N and a signal strength detection unit 152.

The input unit 11 receives an input from the user of the communication device 1 and outputs information indicating the received input to the control unit 13. For example, the input unit 11 receives information indicating that fallback is permitted from the user or information indicating that fallback is not permitted, and outputs the information to the fallback. The input unit 11 is, for example, a touch panel, buttons, a keyboard, or a camera.
The output unit 12 performs output based on the control of the control unit 13. The output unit 12 is, for example, a display, a speaker, a vibrator, or a light emitting element.

  The control unit 13 controls each unit of the communication device 1 based on information input from the input unit 11 or the communication unit 15 or information stored in the storage unit 14. Of the control unit 13, the application unit 131 reads various programs from the storage unit 14 and executes various programs by executing the read program.

The proxy unit P1 causes the information generated by the control unit 13 to be transmitted via one or a plurality of interfaces 151-n (n = 1, 2,..., N). For example, the proxy unit P1 may select one or more of the interfaces 151-1 to 151-N of the communication unit 15 based on information input from the input unit 11 or the communication unit 15 or information stored in the storage unit 14. A plurality of interfaces 151-n are selected. The proxy unit P1 transmits the information generated by the application unit 131 via the selected one or more interfaces 151-n.
Moreover, the proxy part P1 synthesize | combines the received information, when the some interface 151-n receives information. For example, when the plurality of interfaces 151-n are switched over time, the proxy unit P1 may combine the data before and after the switching. Details of the proxy unit P1 will be described later.

  The communication unit 15 can perform communication of a plurality of communication methods. For example, the interface 151-1 can perform Wi-Fi communication. The interface 151-2 can perform LTE communication (also referred to as LTE communication). The interface 151-3 can perform 3G communication (also referred to as 3G communication). Note that the interface 151-n is not limited to wireless communication, and may perform wired communication. Further, the interface 151-n is not limited to a physical interface, and may be a logical interface.

  The signal strength detection unit 152 detects signal strength information indicating the strength of the signal received by the communication signal (reception signal strength) for each interface 151-n. For example, the signal strength detection unit 152 detects an RSSI (Received Signal Strength Indicator (or Indication)) in communication via the interface 151-1 (Wi-Fi communication) and communication via the interfaces 151-2 and 15-3 ( In LTE communication and 3G communication, a CQI (Channel Quality Indicator) may be detected, and the signal strength detection unit 152 outputs the detected signal strength information to the control unit 13 (for example, the proxy unit P1).

<About proxy part P1>
FIG. 3 is a schematic block diagram illustrating a configuration of the proxy unit P1 according to the present embodiment. The proxy unit P1 includes a session management unit P111, a DNS management unit P112, a throughput acquisition unit P113, a capacity information acquisition unit P114, a signal strength acquisition unit P121, a timekeeping unit P122, an AP (access point) information acquisition unit P123, and a communication method information acquisition. Part P124, position information acquisition part P125, header information acquisition part P131, redirect information acquisition part P132, IF selection part P14, and data composition part P15.

  The session management unit P111 manages a session. A session is a series of communications, for example, a unit from establishing a connection to disconnecting. For example, a session is generated for each request from the application, and each session ends after a response to each request. Specifically, the session management unit P111 includes session identification information (also referred to as session identification information), session start time, session end time, request identification information, request application identification information, and success or failure of session establishment. The session abnormality reason information indicating the reason for the session abnormality, the information indicating the wireless link used for the session, and the like are stored in the storage unit 14, and the session is managed by referring to and updating. Session abnormalities include failure to establish a session, timeout of the session, etc., and there are a connection error, a communication error, a socket error, a timeout, and the like.

When a session abnormality occurs, such as when a session cannot be established (for example, connection failure) or when the session times out, the session management unit P111 identifies session abnormality information indicating session abnormality and session abnormality reason information as a session identification. The information is output to the IF selection unit P14 in association with the information.
In addition, the session management unit P111 counts the number of sessions performing fallback (also referred to as the number of FB sessions), and outputs FB session number information indicating the counted number of FB sessions to the IF selection unit P14. Note that fallback occurs for each session, and fallback that occurs in session units is also referred to as “single fallback”.

The DNS management unit P112 manages domain name information in the communication device 1. For example, the DNS management unit P112 transmits the domain name of the content server to the DNS server, and acquires the IP address. This processing of the DNS management unit P112 is also referred to as name resolution processing.
When an abnormality occurs in the name resolution process, the DNS management unit P112 associates name resolution abnormality information indicating the name resolution abnormality and name resolution abnormality reason information indicating the reason for the name resolution abnormality with the session identification information, Output to the IF selector P14. Name resolution abnormalities include name resolution failure (for example, connection failure), name resolution timeout, etc., due to host name or domain name not registered, unregistered, communication error, timeout, etc. There is.

  The throughput acquisition unit P113 calculates the communication throughput based on the amount of information transmitted and received by the communication unit 15. Throughput is the amount of data communicated within a certain time. The throughput of the present embodiment is the throughput of downlink communication, that is, communication from the access point AP1 or the base station apparatus BS1 to the communication apparatus 1, but the present invention is not limited to this. The throughput acquisition unit P113 outputs throughput information indicating the calculated throughput to the IF selection unit P14 in association with the session identification information.

The capacity information acquisition unit P114 manages the capacity of each piece of information related to communication, and generates capacity information indicating the capacity. For example, the capacity information acquisition unit P114 acquires the capacity (also referred to as content size) of content acquired by communication from the content server, and calculates the currently acquired capacity (also referred to as DL size) for the content. . In addition, the capacity information acquisition unit P114 reads the capacity that allows fallback (also referred to as FB allowable size) from the storage unit 14 that stores it in advance. The capacity information acquisition unit P114 outputs the capacity information indicating the content size, the DL completed size, or the FB allowable size to the IF selection unit P14. In addition, when capacity | capacitance information shows each capacity | capacitance for every session, it matches with session identification information and is output to IF selection part P14.
The signal strength acquisition unit P121 acquires signal strength information for each interface 151-n from the signal strength detection unit 152, and outputs the acquired signal strength information to the IF selection unit P14.

The time measurement unit P122 measures time. For example, the time measurement unit P122 measures the elapsed time after transition to the fallback state C13 (described later). When the elapsed time exceeds a set value (for example, 1 minute), the time measuring unit P122 associates the time excess information indicating the time excess with the session identification information and outputs it to the IF selection unit P14.
The AP information acquisition unit P123 acquires the identification information of the access point or base station that is currently communicating or the identification information of the network (such as BSSID or ESSID). The AP information acquisition unit P123 outputs the acquired identification information (also referred to as AP identification information) to the IF selection unit P14.

The communication method information acquisition unit P124 generates communication method information indicating the communication method currently used for communication. For example, the communication method information acquisition unit P124 generates communication method information indicating LTE when performing LTE communication, and communication method information indicating 3G when performing 3G communication. The communication method information acquisition unit P124 outputs the generated communication method information to the IF selection unit P14.
The position information acquisition unit P125 measures the current position of the communication device 1 using, for example, a GPS (Global Positioning System) function. The position information acquisition unit P125 outputs position information indicating the current position of the measured communication device 1 to the IF selection unit P14. The location information acquisition unit P125 is base station information of the base station device BS1 and can estimate an approximate location of the communication device 1 (for example, information indicating a base station device to which the communication device 1 is connected). Or information indicating the position of the base station apparatus), and the acquired base station information may be output as position information to the IF selection unit P14.

The header information acquisition unit P131 acquires HTTP header information for each session from the information transmitted and received by the communication unit 15. The header information acquisition unit P131 outputs the acquired header information to the IF selection unit P14 in association with the session identification information. The header information acquisition unit P131 may acquire HTTP header information for each interface 151-n.
The redirect information acquisition unit P132 acquires an HTTP status code for each session from the information transmitted and received by the communication unit 15. The redirect information acquisition unit P132 outputs the acquired status code to the IF selection unit P14 in association with the session identification information. If the status code indicates redirection, the redirect information acquisition unit P132 also acquires information indicating the redirection destination and outputs the information to the IF selection unit P14.

The IF selection unit P14 selects interfaces 151-1 to 151-N for performing communication for each session based on information input from each unit of the communication device 1. The IF selection unit P14 causes communication in the session to be performed by the interface 151-n selected for each session. Thereby, IF selection part P14 switches the radio link of each session. That is, the IF selection unit P14 controls fallback and failback.
The data synthesis unit P15 synthesizes the information received by the communication unit 15, and outputs the synthesized information to, for example, the application unit 131 and the storage unit 14. For example, when at least two interfaces 151-n are temporally switched in a certain session, the data synthesis unit P15 synthesizes data before and after switching.

<About fallback>
FIG. 4 is an explanatory diagram for explaining fallback according to the present embodiment.
In this figure, the figure with the reference C11 represents the normal state C11, the figure with the reference C12 represents the single fallback state C12, and the figure with the reference C13 represents the fallback state (also called the fallback state). C13). Transition from the normal state C11 to the state C12 occurs when communication fails. Also, the state C12 transitions to the state C13 when the number of FB sessions exceeds the allowable number (also simply referred to as the allowable number). Each arrow from the communication unit 15 to the host represents communication of each session.

In the normal state C11, the communication unit 15 and the host (for example, the access point AP1 and the base station apparatus BS1) perform Wi-Fi communication in all sessions. The state C12 is a state in which, for some sessions, the Wi-Fi communication C121 is stopped and switched to LTE communication or 3G communication (also referred to as cellular communication) C122. That is, the state C12 is a state in which a single fallback is performed from the communication C121 to the communication C122 for a certain session.
The state C13 is a state in which cellular communication is performed in all sessions. The state C13 is a state in which cellular communication is prioritized, and is a state in which, for example, when the allowable number is exceeded, the state is shifted from another Wi-Fi communication to the cellular communication. When the allowable number is exceeded and there is a session in which Wi-Fi communication is being performed, the session is transitioned to cellular communication after the communication is completed. The state C13 is a state in which cellular communication is assigned to a new session.

  Hereinafter, details of the fallback will be described with reference to FIGS. In the following, the original radio link that performs fallback is also referred to as “FB source link”, and the destination radio link that performs fallback is also referred to as “FB destination link”. For example, the FB source link is Wi-Fi communication, and the FB destination link is LTE communication. Further, the interface 151-i (i = 1, 2,..., N) that performs communication in the case of the “FB source link” is also referred to as the FB source interface 151-i, and in the case of the “FB destination link”. The interface 151-k (k = 1, 2,..., N, k ≠ i) that performs communication is also referred to as an FB destination interface 151-k.

A condition for performing a single fallback (also referred to as a single fallback condition) is one of the following (A1) to (A6).
(A1) When session times out (A2) When name resolution processing times out (A3) When throughput decreases (A4) When session cannot be established (A5) When name resolution processing fails (A6) Communication When a socket error occurs during the following, these (A1) to (A6) will be described.

(A1) When the session times out If the communication device 1 times out when making a socket connection with the host, the communication device 1 performs a single fallback. Here, the socket connection is a connection through a connection request interface (for example, socket (), bind (), etc.). Specifically, if the input session abnormality information indicates a timeout, the IF selection unit P14 selects the FB destination interface 151-k for communication of the session indicated by the session identification information. Accordingly, the communication device 1 can switch from communication at the FB source interface 151-i to communication at the FB destination interface 151-k, and switch communication from the FB source link to the FB destination link.

The session management unit P111 reads the initial value (also referred to as initial timeout time) of the timeout time related to the FB source link, the maximum timeout time, and the allowable number of single fallbacks from the storage unit 14 that stores in advance. The session management unit P111 extends the timeout time by the following calculation in proportion to the number of FB sessions. Specifically, the session management unit P111 calculates the timeout increase time by the following formula.
Time-out increase time = (maximum time-out time−initial time-out time) ÷ (allowable number−1)
The session management unit P111 calculates the timeout increase time according to the calculation method related to the FB destination link. For example, in this embodiment, in the case of a cellular connection, when the initial timeout time is “2000 milliseconds”, the maximum timeout time is “3000 seconds”, and the allowable number is “5”, the timeout time is a single session. Each fallback increases by "250 milliseconds".

That is, the session management unit P111 linearly increases the timeout time according to the number of FB sessions. For example, the timeout time can be expressed by the following equation.
Timeout time = (maximum timeout time−initial timeout time) ÷ (allowable number−1) × number of FB sessions + initial timeout time

The session management unit P111 may increase the timeout time non-linearly. For example, the session management unit P111 may increase the timeout time in a quadratic function according to the number of FB sessions. In this case, for example, the timeout time can be expressed by the following equation.
Timeout period = ((maximum timeout period−initial timeout period) ÷ (allowable number−1) ^ 2) × number of FB sessions ^ 2 + initial timeout period

In this way, the communication device 1 weights the timeout time determined to be incapable of communication using the number of FB sessions, so the number of FB sessions is two rather than one, three than two, It can gradually become difficult to fall back.
Note that the session management unit P111 may increase the timeout time exponentially or logarithmically according to the number of FB sessions.

  In the above-described calculation example of the timeout time, the initial timeout time is a fixed value set in advance, but the response delay amount is such that the number of FB sessions is always stable at a number equal to or less than the allowable number. In this case, the initial timeout time may be reset based on the number of FB sessions. For example, when the number of FB sessions is stable at a specific number M (M is an integer) other than 0, the communication device 1 uses the timeout time when the number is “M + 1” as a threshold value and feeds back (reset) the initial timeout time ). As a result, the communication device 1 can hold the fallback up to the response delay amount of the system without repeating M fallbacks unnecessarily.

In the case of cellular connection (LTE communication or 3G communication connection), the session management unit P111 reads the timeout time from the storage unit 14 that stores the timeout time in advance. In the case of a cellular connection, the timeout time is, for example, a fixed value (for example, 3000 milliseconds).
The session management unit P111 determines that the session is abnormal when the response to the socket connection of each communication type (Wi-Fi or cellular type) exceeds the timeout time of the communication type. For example, in the case of a Java (registered trademark, the same applies hereinafter) program (class, instance, method, attribute, etc. are also referred to as a program), the session management unit P111 sets a timeout time in Connect () and generates a SocketTimeoutException. If it does, the session is abnormal. In that case, the session management unit P111 outputs session abnormality information indicating a timeout to the IF selection unit P14.
In the case of cellular connection, the timeout period may be changed according to the number of FB sessions, as in the case of Wi-Fi connection.

(A2) When the name resolution process times out The communication apparatus 1 performs a single fallback when the timeout occurs when connecting to the DNS server by name resolution. In the case of Wi-Fi communication, the DNS management unit P112 acquires a host name and the like from the DNS server. Specifically, if the input name resolution abnormality information indicates a timeout, the IF selection unit P14 selects the FB destination interface 151-k for communication of the session indicated by the session identification information.

Note that the DNS management unit P112 reads out the timeout time for connection to the DNS server from the storage unit 14 that stores in advance. The timeout time of the cellular connection is, for example, a fixed value (for example, 1000 milliseconds). In addition, when the connection to the DNS server times out, the DNS management unit P112 performs reconnection (retry) after 1 second, for example. If reconnection fails, the DNS management unit P112 determines that name resolution is abnormal. Also, in the case of a Java program, the DNS management unit P112 determines that name resolution is abnormal when an Interrupted IOException occurs. Interrupted IOException generates a signal notifying that an interrupt has occurred in the input / output process. When the DNS management unit P112 determines that the name resolution is abnormal, the DNS management unit P112 outputs the name resolution abnormality information to the IF selection unit P14.
Note that when performing a single fallback when the name resolution process times out, the timeout period may be changed according to the number of FB sessions, as in the case where the session times out.

(A3) When throughput decreases When the throughput decreases, the communication device 1 performs a single fallback. Specifically, if the throughput indicated by the input throughput information is equal to or less than a threshold value (also referred to as a throughput threshold value) stored in the storage unit 14, the IF selection unit P14 performs communication regarding the session indicated by the session identification information. The FB destination interface 151-k is selected.
Note that the throughput threshold may be a different value depending on the communication method. For example, the throughput threshold is 512 Kbps in the case of LTE communication. On the other hand, in the case of UMTS / HS (D) PA (Universal Mobile Telecommunication System / High Speed (Downlink) Packet Access), the throughput threshold is 256 Kbps.

  Further, when measuring the throughput of downlink communication, the throughput acquisition unit P113 starts measurement for each session from the start of reception (for example, when a response is read even with 1 byte). Here, the throughput acquisition unit P113 generates a thread and starts monitoring asynchronously before the response data is read. The throughput acquisition unit P113 measures the information amount of response data acquired in one second in byte size. For example, when the communication unit 15 acquires 64 KB (kilobytes) per second, the throughput is 512 Kbps (kilobits / second). Since the throughput acquisition unit P113 starts from the socket connection after the fallback, the throughput acquisition unit P113 skips the information amount (number of bytes) of the response (response already sent to the original application) acquired by the FB source link, and thereafter The amount of information received may be measured.

(A4) When session cannot be established The communication device 1 performs a single fallback when the socket connection with the host fails. Specifically, when the input session abnormality information indicates a connection failure, the IF (interface) selection unit P14 selects the FB destination interface 151-k for communication of the session indicated by the session identification information. In the case of a Java program, the session management unit P111 sets a session error when an IOException is caught (caught) at the time of socket connection. IOException is an exception thrown when an IO (input / output) error occurs. When the session management unit P111 determines that a session is abnormal, the session management unit P111 outputs session abnormality information to the IF selection unit P14.

(A5) When name resolution processing fails When the communication device 1 fails in socket connection with the DNS server, it performs a single fallback. Specifically, when the input name resolution abnormality information indicates a connection failure, the IF selection unit P14 selects the FB destination interface 151-k for communication of the session indicated by the session identification information.

  Note that the DNS management unit P112 reads out the timeout time for connection to the DNS server from the storage unit 14 that stores in advance. If the connection to the DNS server fails, for example, after 1 second, reconnection is performed. If reconnection fails, the DNS management unit P112 determines that name resolution is abnormal. For example, in the case of a Java program, the DNS management unit P112 determines that the name resolution is abnormal when an IOException is caught in the socket connection. Also, the DNS management unit P112 checks the IP address after the name resolution. When the DNS management unit P112 determines that the name resolution is abnormal, the DNS management unit P112 outputs the name resolution abnormality information to the IF selection unit P14.

(A6) When a socket error occurs during communication When the socket error occurs during communication at the FB source, the communication device 1 performs a single fallback. Specifically, if the input session abnormality information indicates a socket error, IF selection unit P14 selects FB destination interface 151-k for communication of the session indicated by the session identification information. In the case of a Java program, the session management unit P111 determines that a session error occurs when a SocketException occurs during communication. A SocketException is an exception thrown when a socket error occurs. When the session management unit P111 determines that a session is abnormal, the session management unit P111 outputs session abnormality information indicating a socket error to the IF selection unit P14.

The conditions for transitioning to the fallback state (state C13 in FIG. 4) are as follows.
(B1) When the number of FB sessions exceeds the allowable number Specifically, the IF selection unit P14 determines that the number of FB sessions indicated by the input FB session number information is the allowable number (for example, “ 5 ”), the LTE communication interface 151-2 is selected for all sessions. Thereby, the communication part 15 will perform the communication which the state C13 of FIG. 4 represents. The session management unit P111 determines the number of sessions that have been subjected to a single fallback when (A1) the session has timed out, (A2) the name resolution process has timed out, (A3) when the throughput has decreased, It is a number. However, the present invention is not limited to this, and in all cases (A1) to (A6), the number of fallback sessions may be the number of FB sessions.
Further, the IF selection unit P14, when (A4) session cannot be established in a session, (A5) when name resolution processing fails, (A6) when a socket error occurs during communication, For this session, the LTE communication interface 151-2 may be selected.

<About failback>
FIG. 5 is an explanatory diagram for explaining failback according to the present embodiment. Note that the failback means returning to the state before the fallback by performing the reverse switching to the fallback.
In this figure, the normal state C11 and the fallback state C13 are the same as those in FIG. The diagram with the symbol C22 represents a failback state (also referred to as a failback state) C22. Transition from the fallback state C13 to the failback state occurs when a failback condition described later is satisfied. In addition, the state C22 is sequentially changed to the state C11. Each arrow from the communication unit 15 to the host represents communication of each session.

  The state C22 is a state in which the cellular communication C221 is stopped and switched to the Wi-Fi communication C222 for some sessions. That is, the state C22 is a state in which a failback is performed from the communication C221 to the communication C222 for a certain session. When there is a session in the middle of performing cellular communication when performing failback, the session is shifted to Wi-Fi communication after the communication is completed. For example, the communication continues with the same bearer until the communication is completed. In addition, states C22 and C11 are states in which Wi-Fi communication is assigned to a new session.

  Hereinafter, details of failback will be described with reference to FIGS. The original radio link that performs failback is the above-mentioned FB destination link, and the destination radio link that performs failback is the above-mentioned FB source link.

The failback condition is one of the following (C1) to (C5).
(C1) When the signal strength of the FB source link increases (C2) When 1 minute has passed since fallback (C3) When the access point changes (C4) When LTE communication changes to 3G communication (C5) Communication When a socket error occurs during

(C1) When the signal strength of the FB source link increases The communication device 1 performs failback when the signal strength of the FB source link increases more than a predetermined strength from when it falls back. Specifically, the IF selection unit P14 stores signal strength information (also referred to as FB signal strength information) at the time of fallback in the storage unit 14 for the signal strength information of the FB source interface 151-i that is input as needed. The FB signal strength information is subtracted from the current signal strength information. If the subtracted value (also referred to as intensity difference) is equal to or greater than a predetermined threshold, the IF selection unit P14 performs failback. For example, when the communication method of the FB source link is Wi-Fi communication, the IF selection unit P14 selects the FB source interface 151-i when the RSSI intensity difference is 2 ranks (for two antennas) or more. . Thereby, the communication apparatus 1 can switch from communication at the FB destination interface 151-k to communication at the FB source interface 151-i, and switches communication from the FB destination link to the FB source link. Note that the IF selection unit P14 may calculate a ratio between the current signal strength information and the FB signal strength information and compare it with a threshold value.

In addition, when the FB signal strength information is 3 ranks (for 3 antennas), the IF selection unit P14 has a strength of 1 when the current signal strength information is 4 ranks (for 4 antennas: maximum rank). Fail back even if it is a rank. Further, the IF selection unit P14 may perform failback when the current signal strength information exceeds a predetermined value. For example, when the highest rank (for four antennas) is reached, failback is performed. You may go.
Here, the signal strength detection unit 152 is realized by using, for example, WiFiManager. WifiManager is a program for acquiring Wi-Fi information, and can acquire BSSID, IP address, network ID, and the like. The signal strength detection unit 152 detects the RSSI of WiFi communication at the FB source interface 151-i, for example, at intervals of 5 seconds. The signal strength detection unit 152 outputs signal strength information indicating the detected RSSI to the IF selection unit P14 via the signal strength acquisition unit P121 at intervals of 5 seconds.

(C2) When 1 minute has elapsed since fallback The communication device 1 performs failback when 1 minute or more has elapsed since the transition to the fallback state C13. Specifically, the IF selection unit P14 selects the FB source interface 151-i when time-exceeded information is input, that is, when a set value (for example, 1 minute) has elapsed from the time of fallback. To do.

(C3) When the access point is changed The communication device 1 performs failback when the identification information of the base station of the FB source link or the identification information of the network is changed. Specifically, the IF selection unit P14 determines whether the input AP identification information is different before and after the fallback. If it is determined that there is a difference between before and after the fallback, the IF selection unit P14 selects the FB source interface 151-i. Note that the IF selection unit P14 may use (C3) as a failback condition only in the case of forced fallback.
Here, the AP information acquisition unit P123 acquires the BSSID when receiving, for example, CONNECTIVITY_ACTION. CONNECTIVITY_ACTION is a program that acquires a notification when the network connection state changes.

(C4) When LTE communication is changed to 3G communication When the communication method of the FB destination link is LTE, the communication device 1 performs failback when the communication method is changed to 3G. Specifically, the IF selection unit P14 selects the FB source interface 151-i when the input communication method information changes from LTE to 3G after performing fallback. Note that the IF selection unit P14 may use (C4) as a failback condition only in the case of forced fallback. Here, for example, when receiving the CONNECTIVITY_ACTION, the communication method information acquisition unit P124 acquires the cellular type by acquiring the cellular type. In addition, when changing communication from LTE to 3G, the communication device 1 may perform header comparison processing to control whether to acquire data from the beginning or from the middle. Here, the communication device 1 compares the header information acquired using the FB source link (Wi-Fi communication) and the header acquired using the link (3G communication) after the change in the FB destination link, You may perform a header comparison process.

(C5) When a socket error occurs during communication If the socket error occurs during communication at the FB destination, the communication device 1 performs failback. Specifically, the IF selection unit P14 selects the FB source interface 151-i when the input session abnormality information indicates a socket error.

When failback is performed, the IF selection unit P14 may cancel the “forced fallback mode” state. After the cancellation, the IF selection unit P14 preferentially selects Wi-Fi communication.
Further, after failback is performed, if communication on the FB source link fails, the communication device 1 may perform fallback. Furthermore, after performing this fallback, when communication fails in the FB destination link, the communication device 1 may stop communication. Thereby, the communication device 1 can prevent the fallback and the failback from being repeated.

<About header comparison processing>
When performing the above fallback, the communication device 1 performs a header comparison process. Specifically, the header information acquisition unit P131 acquires, for example, when header information (also referred to as FB source header information) of a predetermined protocol (for example, HTTP) is acquired in the FB source link before performing fallback. The FB source header information is output to the IF selection unit P14. The IF selection unit P14 causes the storage unit 14 to store the input FB source header information as. When performing fallback, the header information acquisition unit P131 acquires protocol header information (FB destination header information) in the FB destination link, and outputs the acquired FB destination header information to the IF selection unit P14. The IF selection unit P14 compares the FB source header information and the FB destination header information.
Here, the IF selection unit P14 compares information in the header information that can be determined to have a difference in the HTTP data portion. For example, the IF selection unit P14 compares information indicating the size of the content (Content-Length) and information indicating the version and update date / time of the header information.

As a result of the comparison, when it is determined that the FB source header information and the FB destination header information are the same, the IF selection unit P14 selects the FB destination interface 151-k for the communication of the session indicated by the session identification information (fallback) I do).
On the other hand, if it is determined as a result of the comparison that the header information H1 and the header information H2 are not the same, the IF selection unit P14 keeps the FB source interface 151-i for the communication of the session indicated by the session identification information (fallback). Cancel).

If the IF selection unit P14 determines that the header information H1 and the header information H2 are not the same, the IF selection unit P14 may try fallback again according to the status code acquired by the redirect information acquisition unit P132. Specifically, when it is determined that the header information H1 and the header information H2 are not the same, the header information acquisition unit P131 makes an HTTP range request to the redirection destination acquired by the redirect information acquisition unit P132. The header information acquisition unit P131 acquires new header information as a result of the range request, and outputs the acquired header information to the IF selection unit P14 as FB destination header information. The IF selection unit P14 compares the newly acquired FB destination header information with the FB source header information.
As a result of the comparison, when it is determined that the FB source header information and the FB destination header information are the same, the IF selection unit P14 selects the FB destination interface 151-k for the communication of the session indicated by the session identification information (fallback) I do). On the other hand, if it is determined as a result of the comparison that the header information H1 and the header information H2 are not the same, the IF selection unit P14 keeps the FB source interface 151-i for the communication of the session indicated by the session identification information (fallback). Cancel).

FIG. 6 is a diagram illustrating state transition of the communication device 1 according to the present embodiment. In this figure, a state S11 with S11 indicates a state in which Wi-Fi communication is performed (also referred to as WiFi communication state S11). State S12 with S12 indicates a state in which cellular communication is performed (also referred to as cellular communication state S12).
When the communication device 1 is in the WiFi communication state S11 and the Wi-Fi communication is good, for example, when the conditions (A1) to (A6) for performing the single fallback are not satisfied, the communication device 1 is in the WiFi communication state S11. It remains. On the other hand, when the communication device 1 is in the WiFi communication state S11 and falls under the conditions (A1) to (A6) for performing the single fallback, the communication device 1 transitions to the cellular communication state S12 by performing the fallback. .

  When the communication device 1 is in the cellular communication state S12, for example, when the failback conditions (C1) to (C5) are not satisfied, the communication device 1 remains in the cellular communication state S12. In addition, when the communication device 1 is in the cellular communication state S12, even when the cellular communication fails, the communication device 1 remains in the cellular communication state S12. On the other hand, when the communication device 1 is in the cellular communication state S12, for example, when the failback conditions (C1) to (C5) are satisfied, the communication device 1 transitions to the WiFi communication state S11 by performing failback.

  FIG. 7 is an explanatory diagram for state transition of the communication device 1 according to the present embodiment. In this figure, each column represents a condition, a Wi-Fi communication state S11, and a cellular communication state S12. The information denoted by reference sign T11 represents a case where the condition is a session timeout (session connection timeout) or a name resolution processing timeout (DNS connection timeout). Hereinafter, the timeout of the session or name resolution processing is also referred to as timeout.

  For example, when the line information (also referred to as line information) T111 does not time out in Wi-Fi communication (successful connection) and does not time out in cellular communication (successful connection), the communication apparatus 1 is in Wi-Fi communication state S11. If there is, the Wi-Fi communication state S11 is continued, and if the cellular communication state S12, the cellular communication state S12 is continued. If the communication apparatus 1 is in the Wi-Fi communication state S11 when the line information T112 does not time out in the Wi-Fi communication (successful connection) and times out in the cellular communication (connection failure), the row information T112 displays If the cellular communication state S12 continues, it indicates that the communication connection is stopped. If the communication apparatus 1 is in the Wi-Fi communication state S11 when the line information T113 times out in Wi-Fi communication (connection failure) and does not time out in cellular communication (successful connection), the line information T113 transits to the cellular communication state S12 ( If the single fallback condition (A1), (A2)) and the cellular communication state S12, it means that the cellular communication state S12 is continued. In FIG. 7, a fallback marked with * such as “fallback (*)” is counted by the session management unit P111 as the number of FB sessions when a single fallback is performed.

  The information denoted by reference sign T12 represents a case where the conditions are success or failure of session establishment (session connection) and success or failure of name resolution processing (name resolution). Hereinafter, session establishment or name resolution processing is also referred to as connection processing. For example, the row information T123 indicates that the communication apparatus 1 is in the Wi-Fi communication state S11 when the connection process fails in Wi-Fi communication (connection failure) and the connection process succeeds in cellular communication (connection success). Transition to the cellular communication state S12 (single fallback conditions (A4), (A5)) indicates that the cellular communication state S12 is continued if the cellular communication state S12.

  The information with the symbol T13 represents that the condition is based on the result of state monitoring. The row information T131 represents that when the throughput decreases, if the communication device 1 is in the Wi-Fi communication state S11, the line information T131 transits to the cellular communication state S12 (single fallback condition (A3)). The row information T132 indicates that when the signal strength of Wi-Fi communication increases, the communication device 1 transitions to the Wi-Fi communication state S11 if the communication device 1 is in the cellular communication state S12 (failback condition (C1)). The row information T133 indicates that when the access point changes, if the communication device 1 is in the cellular communication state S12, the line information T133 transits to the Wi-Fi communication state S11 (failback condition (C3)). The row information T134 indicates that when the LTE communication is changed to 3G communication, the communication apparatus 1 transits to the Wi-Fi communication state S11 if the communication device 1 is in the cellular communication state S12 (failback condition (C4)).

  The information with the symbol T14 represents other conditions. The row information T141 indicates that, when one minute has elapsed from the fallback, if the communication device 1 is in the cellular communication state S12, the line information T141 transits to the Wi-Fi communication state S11 (failback condition (C2)). The line information T142 transitions to the cellular communication state S12 if the communication device 1 is in the Wi-Fi communication state S11 when a socket error (SocketException) occurs during communication (single fallback condition (A6)). If it is the cellular communication state S12, it represents transition to the Wi-Fi communication state S11 (failback condition (C5)). For example, if the session management unit P111 detects a socket error, the IF selection unit P14 selects the FB source interface 151-i. Thereby, the communication apparatus 1 can switch from communication at the FB destination interface 151-k to communication at the FB source interface 151-i, and switches communication from the FB destination link to the FB source link.

<Processing flow>
FIG. 8 is a diagram illustrating a processing flow of the communication device 1 according to the present embodiment. In this figure, steps S103, S104, S105, S111, S121, S122, S128, and S129 are information processing for Wi-Fi communication (FB source). Steps S106, S107, S108, S123, S124, and S125 are information processing of cellular communication (FB destination).

(Step S101) The IF selection unit P14 determines whether or not fallback is in progress for all sessions, that is, whether or not the fallback state S13 in FIG. If it is determined that all sessions are falling back (Yes), the process proceeds to step S102. On the other hand, if it is determined that at least some sessions are not in fallback (No), the process proceeds to step S103.

(Step S <b> 102) The IF selection unit P <b> 14 determines whether or not the communication is acquisition of information by DLM (Download Manager). DownloadManager is a program used when acquiring a large file. In other words, the IF selection unit P14 determines whether to acquire a large file. If it is determined that information is acquired by DLM (Yes), the process proceeds to step S103. On the other hand, when it is determined that the information is not acquired by the DLM (No), the process proceeds to step S106.

(Step S103) The DNS management unit P112 requests acquisition of domain name information (for example, an IP address) by a DNS request using Wi-Fi communication. If domain name information is acquired as a result of this request, the process proceeds to step S104. On the other hand, when domain name information is not acquired, IF selection part P14 selects FB destination interface 151-k, and it progresses to step S106.
(Step S104) The session management unit P111 requests connection to the content server by a connection request (Connect) using Wi-Fi communication. If the session management unit P111 fails to connect as a result of this request, the process proceeds to step S106. On the other hand, if the session management unit P111 has successfully connected, the process proceeds to step S105.

(Step S105) The header information acquisition unit P131 uses the Wi-Fi communication to request acquisition of the FB source header information (header DL (Wi-Fi)). When the FB source header information is acquired, the capacity information acquisition unit P114 stores the FB source header information and extracts the acquisition target content size from the FB source header information. In addition, the control unit 13 starts content acquisition.
When the control unit 13 is acquiring content, the capacity information acquisition unit P114 calculates a DL size at any time. Further, the capacity information acquisition unit P114 calculates the remaining size by subtracting the DL completed size from the content size. The remaining size is the capacity of content that has not been acquired from the content to be acquired. Further, when the control unit 13 is acquiring content, the throughput acquisition unit P113 calculates the throughput at predetermined time intervals as needed.

(Step S106) The DNS management unit P112 requests acquisition of domain name information by a DNS request using cellular communication. If domain name information is acquired as a result of this request, the process proceeds to step S107. On the other hand, when domain name information is not acquired, it progresses to step S110.
(Step S107) The session management unit P111 requests connection to the content server by a connection request using cellular communication. If the session management unit P111 fails to connect as a result of this request, the process proceeds to step S110. On the other hand, if the session management unit P111 has successfully connected, the process proceeds to step S108.

(Step S108) The header information acquisition unit P131 requests the acquisition of the FB destination header information using cellular communication (header DL (Cellular)). When the FB destination header information is acquired, the capacity information acquisition unit P114 extracts the acquisition target content size from the FB destination header information. Thereafter, the process proceeds to step S109.
(Step S109) The IF selection unit P14 determines whether or not the content size extracted in Step S108 is larger than a predetermined FB allowable size. The FB allowable size is information indicating the capacity of content that allows fallback. When it is determined that the content size is larger than the FB allowable size (Yes), the process proceeds to step S110. On the other hand, when it is determined that the content size is equal to or smaller than the FB allowable size (No), the control unit 13 starts acquisition of the content using cellular communication.
(Step S110) IOException or InterruptedIOException is thrown. In this case, the control unit 13 determines that there is no good connection or that unconditional fallback is impossible, and stops the communication connection of the communication device 1.

(Step S111) The IF selection unit P14 determines whether or not the throughput calculated by the throughput acquisition unit P113 is equal to or less than the throughput threshold. When the throughput is higher than the throughput threshold, the control unit 13 continues to acquire content using Wi-Fi communication. On the other hand, if it is determined that the throughput is equal to or less than the throughput threshold, the process proceeds to step S112.

(Step S112) Whether the remaining size calculated in step S105, that is, the capacity of the content that has not been acquired at the time of step S112 (or S111), is larger than a predetermined FB allowable size (step S112) Determine whether or not. When it is determined that the remaining size is larger than the FB allowable size (Yes), the process proceeds to step S113. On the other hand, when it is determined that the remaining size is equal to or less than the FB allowable size (No), the process proceeds to step S121.
(Step S113) The IF selection unit P14 determines whether fallback is being performed in all sessions. If it is determined that all sessions are falling back (Yes), the process returns to step S112. In this case, the control unit 13 performs periodic polling (periodic inquiry). Note that it is determined that all sessions are falling back (Yes) only when it is determined in step S102 that information is acquired by DLM. On the other hand, if it is determined that at least some sessions are not in fallback (No), the process proceeds to step S114.

(Step S114) The control unit 13 causes the output unit 12 to output information for confirming whether or not to fall back to the user. For example, the output unit 12 displays “This is a large communication. Do you want to fall back?”. For example, the charge may differ between when content is acquired by cellular communication and when it is acquired by Wi-Fi communication. That is, when the communication device 1 acquires a large-sized content by cellular communication, it may be expensive compared to Wi-Fi communication, so whether or not the content may be acquired by cellular communication. To the user.
When there is no input from the input unit 11 with respect to the output of the output unit 12 (unselected), the process returns to step S112. In this case, the control unit 13 performs regular polling. When there is an input, if the input from the input unit 11 indicates that a fallback is to be performed (Yes), the IF selection unit P14 determines that the fallback is permitted, and the process proceeds to step S121. On the other hand, when the input from the input unit 11 indicates that no fallback is performed (No), the process proceeds to step S128. That is, the communication apparatus 1 does not perform fallback by a user operation.

(Step S121) The control unit 13 stops reading of the reception buffer (ReadStop). Thereafter, the process proceeds to step S122.
(Step S122) The control unit 13 stops writing to the application buffer (WriteStop). That is, the control unit 13 interrupts output of data to the application. Thereafter, the process proceeds to step S123.

(Step S123) The DNS management unit P112 requests acquisition of domain name information by a DNS request using cellular communication. If domain name information is acquired as a result of this request, the process proceeds to step S124. On the other hand, when domain name information is not acquired, it progresses to step S128.
(Step S124) The session management unit P111 requests connection to the content server by a connection request using cellular communication. If the session management unit P111 fails to connect as a result of this request, the process proceeds to step S128. On the other hand, if the session management unit P111 has successfully connected, the process proceeds to step S125.

(Step S125) The header information acquisition unit P131 acquires FB destination header information using cellular communication. Thereafter, the process proceeds to step S126.
(Step S126) The IF selection unit P14 compares the FB source header information stored in Step S105 with the FB destination header information acquired in Step S125 (header comparison process). As a result of the comparison, when it is determined that the FB source header information and the FB destination header information are not the same (Yes), the process proceeds to step S127. On the other hand, when it is determined that the FB source header information and the FB destination header information are the same (No), the control unit 13 resumes content acquisition using cellular communication. Here, the data synthesizing unit P15 reads the data of the content already acquired by Wi-Fi communication, and resumes the data acquisition from the continuation of the data using cellular communication. That is, the communication device 1 succeeds in fallback.
The IF selection unit P14 continues the session in the fallback source communication (Wi-Fi communication) until it determines No in step S126.

(Step S127) The IF selection unit P14 determines whether or not the status code acquired by the redirect information acquisition unit P132 indicates redirection. If it is determined that the status code does not indicate redirection, the process proceeds to step S128.
On the other hand, if it is determined that the status code indicates redirection, the process returns to step S123. In this case, the connection is made to the redirection destination in steps S123 to S125. For example, in step S125, the header information acquisition unit P131 sets the header information acquired from the redirection destination as FB destination header information. Thereafter, in step S126, the new FB destination header information and the FB source header information are compared. Note that the process of step S127 may be performed only once. That is, the control unit 13 may allow the transfer only once. In this case, the IF selection unit P14 proceeds to step S128 without performing the process of step S127 for the second and subsequent times in the same session.

(Step S128) The control unit 13 resumes reading of the reception buffer (ReadStart). That is, the control unit 13 resumes content acquisition using Wi-Fi communication again. Here, the data synthesizing unit P15 reads content data that has already been acquired by Wi-Fi communication, and resumes data acquisition from the continuation of the data using Wi-Fi communication. That is, the communication device 1 stops the fallback and resumes data acquisition by the original FB original communication.
(Step S129) The control unit 13 resumes writing to the application buffer (WriteStart). That is, the control unit 13 resumes outputting data to the application.
In addition, IF selection part P14 may determine whether the communication apparatus 1 is a forced fallback mode in step S101, S113.

Note that in acquiring a DNS request, connection request, or header information, the control unit 13 (session management unit P111, DNS management unit P112, or header information acquisition unit P131) determines the time for determining an abnormality (failure) as the number of FB sessions. You may change according to. For example, when the number of FB sessions is “0”, the control unit 13 determines that the communication response is not “0.2” seconds or longer, and determines that it is abnormal, and when the number of FB sessions is “3”, the communication response Is determined to be abnormal if there is no "2.6" seconds or more. In this way, for example, the control unit 13 increases the time for determining an abnormality as the number of FB sessions increases. Thereby, the communication apparatus 1 can prevent that all communications are easily fallbacked, for example, when the connection environment of Wi-Fi communication in use is constantly delayed.
Moreover, IF selection part P14 may determine whether the communication apparatus 1 is a forced fallback mode in step S101, S113.

<Processing flow of proxy unit P1>
9 and 10 are diagrams illustrating a processing flow of the proxy unit P1 according to the present embodiment. FIG. 10 is a continuation of FIG.
(Step S201) The proxy unit P1 generates a proxy service (LaProxyService) CL21 (onCreate ()). Thereafter, the process proceeds to step S202.
(Step S202) The proxy service CL21 generates an FB management (FallbackManager) CL22 that manages fallback. Then, it progresses to step S203.

(Step S203) The proxy service CL21 generates a server socket (ServerSocket). The server socket is a program that accepts a socket connection. Thereafter, the process proceeds to step S204.
(Step S204) The proxy service CL21 receives a socket connection request from an application (also referred to as an original application) of the communication device 1 (application unit 131), for example. Thereafter, the process proceeds to step S205.
(Step S205) The proxy service CL21 generates an FB session (Fallback Session) CL23 for managing the session. Thereafter, the process proceeds to step S206.

(Step S206) The proxy service CL21 starts the FB session CL23. Thereafter, the process proceeds to step S207.
(Step S207) The FB session CL23 generates a program (read ()) for reading input data. Thereafter, the process proceeds to step S208.
(Step S208) The FB session CL23 reads the request received in Step S204. Thereafter, the process proceeds to step S209.

(Step S209) The FB session CL23 generates a program (connect ()) for establishing a connection. Thereafter, the process proceeds to step S210.
(Step S210) The FB session CL23 analyzes the URL of the request read in Step S208. Then, it progresses to step S211.
(Step S211) The FB session CL23 corrects and deletes unnecessary requests for the request read in Step S208. Thereafter, the process proceeds to step S212.

(Step S212) The FB session CL23 confirms whether LA (Link Aggregation) is valid or invalid. Thereafter, the process proceeds to step S213.
(Step S213) The FB session CL23 requests the FB management CL22 to select a communication method (RAT: Radio Access Technology). Thereafter, the process proceeds to step S214.
(Step S214) The FB management CL 22 selects a communication method (RAT selection). For example, the FB management CL 22 selects Wi-Fi communication by default. On the other hand, for example, in the case of the forced fallback mode, cellular communication is selected. Thereafter, the process proceeds to step S215.

(Step S215) The FB session CL23 generates a program (clientConnect ()) for connecting to the host. Thereafter, the process proceeds to step S216.
(Step S216) The FB session CL23 acquires the IP address of the host by performing name resolution processing on the domain name information included in the request of Step S208. Here, when Wi-Fi communication is selected in step S213, the FB session CL23 selects a DNS server (server device Sv103 in FIG. 1) according to a predetermined rule, and connects to the selected DNS server. The FB session CL23 performs name resolution processing using the connected DNS server. On the other hand, when cellular communication is selected in step S213, the FB session CL23 performs name resolution processing using a predetermined DNS server (server device Sv102 in FIG. 1). Thereafter, the process proceeds to step S217.
Note that if the connection to the DNS server times out or the connection to the DNS server fails in step S216, the communication device 1 determines that the fallback conditions (A2) and (A5) are met.

(Step S217) The FB session CL23 performs socket connection. Here, if the FB session CL23 is already connected to the host and is the same as the host IP address acquired in step S216, the FB session CL23 uses the connected socket connection. On the other hand, in other cases (for example, when not connected), the FB session CL23 uses the IP address of the host acquired in step S216 to generate a socket for connecting to the host. The FB session CL23 connects to the host using the generated socket. For example, the FB session CL23 normally connects to the host through Wi-Fi communication (default). Note that if the connection to the host times out or the connection to the host fails in step S217, the communication device 1 determines that the fallback conditions (A1) and (A4) are met.
If an error has occurred in the processing of steps S215 to S217 (clientConnect ()), the process proceeds to step S218. On the other hand, if no error has occurred in steps S214 to S217, the process proceeds to step S219 in FIG.

(Step S218) The FB session CL23 performs a retry. That is, the FB session CL23 performs the processing of steps S214 to S217 again with a communication method different from the communication method selected in step S213. In other words, the FB session CL23 performs the processes of steps S214 to S217 again using the interface 151-k different from the interface 151-i selected in step S213. That is, the communication device 1 performs fallback. Here, the FB session CL23 determines whether or not to retry by performing a header comparison process and an RD destination information acquisition process before retrying. If no error has occurred in the processes in steps S215 to S217 again, the process proceeds to step S219 in FIG.
(Step S219) The FB session CL23 generates a program (sendRequest ()) for transmitting an HTTP request to the server. Thereafter, the process proceeds to step S220.

(Step S220) The FB session CL23 writes a request for data to the buffer. Thereafter, the process proceeds to step S221.
(Steps S221 and S222) The FB session CL23 transmits the request written in Step S220 to the host connected in Step S217. If the request in step S221 fails, the process proceeds to step S223. On the other hand, if the request in step S221 is successful, the process proceeds to step S224.
(Step S223) The FB session CL23 performs a retry. That is, the communication device 1 performs fallback. Details of this fallback will be described later with reference to FIG.
(Step S224) The FB session CL23 generates a program (recvResponse ()) for receiving a response. Thereafter, the process proceeds to step S224.
(Step S225) The FB session CL23 generates a thread CL24. A thread is a program for receiving data. Thereafter, the process proceeds to step S226.
(Step S226) The FB session CL23 starts the thread CL24. Then, it progresses to step S227 and step S237.

(Step S227) The thread CL24 generates a program (recvResponseHeader ()) for receiving response header information. Thereafter, the process proceeds to step S228.
(Steps S228 and S229) The thread CL24 receives the header information of the response to the request transmitted in Step S221, and reads the received header information. Thereafter, the process proceeds to step S230.
(Steps S230 and S231) The thread CL24 writes the header information read in Step S228 to the socket of the original application. That is, the thread CL24 transmits header information to the original application. Thereafter, the thread CL24 repeats the processes in steps S228 to S231 until reception of all header information is completed. When reception of all responses is completed, the process proceeds to step S232.

(Step S232) The thread CL24 generates a program (recvResponseBody ()) for receiving the body information (data part) of the response. Thereafter, the process proceeds to step S233.
(Steps S233 and S234) The thread CL24 receives the body information of the response to the request transmitted in Step S223, and reads the received body. Thereafter, the process proceeds to step S235.
(Steps S235 and S236) The thread CL24 writes the body information read in Steps S233 and S234 to the socket of the original application. That is, the thread CL24 transmits body information to the original application. Thereafter, the thread CL24 repeats the processes in steps S233 to S236 until reception of all body information is completed.

(Step S237) The FB session CL23 monitors the throughput. The FB session CL23 repeats the process of step S231 or S236 until the thread CL24 completes reception of all header information and body information. Thereafter, the process proceeds to step S239. However, if it is determined in step S229 or S234 that the throughput is equal to or less than the throughput threshold value, it is determined that the fallback condition (A3) is satisfied, and the process proceeds to step S238 in FIG. If an error occurs during the processing of steps S228 to S236, that is, during response acquisition, the process proceeds to step S239.
(Step S238) The FB session CL23 retries, for example, when the throughput decreases. That is, the communication device 1 performs fallback. The case where the throughput decreases is, for example, 512 Kbps (kilobit per second) when the FB source link is Wi-Fi communication, 512 Kbps when the FB source link is LTE communication, and the FB source link is In the case of 3G communication, it is 256. Details of this fallback will be described later with reference to FIGS.
(Step S239) The FB session CL23 performs a retry. That is, the communication device 1 performs fallback. Details of this fallback will be described later with reference to FIG.

  FIG. 11 is another diagram showing a processing flow of the proxy unit P1 according to the present embodiment. This figure is a continuation of step S218 in FIG. 10, and step S301 and subsequent steps in FIG. 11 correspond to step S223 in FIG. Step 223 in FIG. 10 corresponds to S304 and subsequent steps in FIG. In FIG. 11, the processes denoted by the same reference numerals as those in FIG. 9 or FIG. 10 are the same as those in FIG. 9 or FIG.

(Step S301) The FB session CL23 fails the request transmitted in step S221. Note that this request is transmitted by Wi-Fi communication, for example. Thereafter, the process proceeds to step S302.
(Step S302) The FB session CL23 closes the socket generated in Step S217. Thereafter, the process proceeds to step S303.
(Step S303) The FB session CL23 generates a program (doRetry) for performing fallback. Thereafter, the process proceeds to step S304.

(Step S304) The FB session CL23 generates a socket for performing fallback. Thereafter, the process proceeds to step S305.
(Step S305) The FB session CL23 acquires the IP address of the host by performing name resolution processing on the domain name information included in the request of Step S208. Here, the FB session CL23 performs name resolution processing using a DNS server (server device Sv102 in FIG. 1) used in cellular communication. Thereafter, the process proceeds to step S306. In step S305, if the connection to the DNS server times out or the connection to the DNS server fails, the communication device 1 determines that the fallback is also impossible and sets a communication error.

(Step S306) The FB session CL23 performs socket connection. Here, the FB session CL23 generates a socket for connecting to the host by using the IP address of the host acquired in step S305. The FB session CL23 connects to the host through cellular communication using the generated socket. Thereafter, the process proceeds to step S307. In step S306, if the connection to the host times out or the connection to the host fails, the communication device 1 determines that fallback is also impossible and sets a communication error.
(Step S307) The FB session CL23 generates a program (sendRequest ()) for transmitting a request for requesting data. Thereafter, the process proceeds to step S308.
(Steps S308 and S309) The FB session CL23 transmits a request for data to the host connected in step S306 by cellular communication. Thereafter, the process proceeds to step S310.

(Step S310) The FB session CL23 generates a program (recvResponseHeader ()) for receiving response header information. Thereafter, the process proceeds to step S311.
(Steps S311 and S312) The FB session CL23 receives the header information of the response and reads the received header information. Thereafter, the process proceeds to step S313.
(Steps S313 and S314) The FB session CL23 writes the header information read in Step S311 to the socket of the original application. That is, the FB session CL23 transmits header information to the original application. Thereafter, the FB session CL23 repeats the processes of steps S311 to S314 until reception of all header information is completed. When reception of all responses is completed, the process proceeds to step S315. Here, the FB session CL23 does not perform header comparison processing (for example, content size comparison processing) after step S314 and before step S315. This is because the communication apparatus 1 has not acquired the FB source header information because the request has failed in step S301.

(Step S315) The FB session CL23 generates a program (recvResponseBody ()) for receiving the body information (data part) of the response. Thereafter, the process proceeds to step S316.
(Steps S316 and S317) The FB session CL23 receives the body information of the response to the request transmitted in step S309, and reads the received body. Thereafter, the process proceeds to step S318.
(Steps S318 and S319) The FB session CL23 writes the body information read in Steps S316 and S317 to the socket of the original application. That is, the FB session CL23 transmits the body information to the original application. Thereafter, the FB session CL23 repeats the processes of steps S316 to S319 until reception of all body information is completed. After reception of all body information is completed, the process proceeds to step S320.
(Step S320) The FB session CL23 sets (updates) the socket information after the FB in the information of the socket connected to the server device, which is internal information.

  FIG. 12 is another diagram showing a processing flow of the proxy unit P1 according to the present embodiment. This figure is a continuation of step S223 in FIG. In FIG. 11, the processes denoted by the same reference numerals as those in FIG. 9, FIG. 10, or FIG. 11 are the same as those in FIG. 9, FIG. 10, or FIG.

(Step S401) The FB session CL23 generates a program (doRetry) for performing fallback. Thereafter, the process proceeds to step S304.
In FIG. 12, after step S312, the process proceeds to step S402. Further, the case where the processes in S304, S306, and S309 have failed will be described with reference to FIG.
(Step S402) The FB session CL23 compares the header information (FB source header information) read in steps S228 to S231 and the header information (FB destination header information) read in steps S311 to S312 (for example, Content size comparison process). If it is determined that the FB source header information and the FB destination header information are the same (for example, the content size is the same), the process proceeds to step S403. A case where it is determined that the FB source header information and the FB destination header information are not the same will be described with reference to FIG.

(Step S403) The FB session CL23 starts fallback. Thereafter, the process proceeds to step S404.
(Step S404) The FB session CL23 causes the FB management CL22 to add 1 to the number of FB sessions. The FB session CL23 sets a throughput reduction flag indicating that the throughput has been reduced. When this flag is set, the thread CL24 exits the loop of steps S233 to S236. Then, it progresses to step S315 and S405.
(Step S405) The thread CL24 closes the socket generated in step S217 of FIG. The FB session CL23 reads body information from the continuation of the body information written in the last step S236 in the first step S316 of FIG.

  FIG. 13 is another diagram illustrating a processing flow of the proxy unit P1 according to the present embodiment. This figure is a continuation of step S223 in FIG. In FIG. 11, the processes denoted by the same reference numerals as those in FIGS. 9 to 12 are the same as those in FIGS. Note that if the processing in steps S304, S306, and S309 in FIG. 13 fails, the process proceeds to step S502.

(Step S501) The FB session CL23 compares the header information (FB source header information) read in Steps S228 to S231 and the header information (FB destination header information) read in Steps S311 to S312 (for example, Content size comparison process). If it is determined that the FB source header information and the FB destination header information are not the same (for example, the content size is the same), the process proceeds to step S502. Note that the FB session CL23 may perform the process of step S127 of FIG. 8 after step S501. At this time, if it is determined that the status code indicates redirection, the process returns to step S123. In this case, returning to step S307, a program (sendRequest ()) for transmitting a request for requesting data to the redirection destination may be generated.
(Step S502) The FB session CL23 closes the socket generated in Step S304.

  FIG. 14 is another diagram showing a processing flow of the proxy unit P1 according to the present embodiment. This figure is a continuation of step S223 in FIG. In FIG. 11, the processes denoted by the same reference numerals as those in FIGS. 9 to 12 are the same as those in FIGS.

(Steps S601, S602, and S603) The thread CL24 cannot receive response header information or cannot receive all header information in response to the request transmitted in Step S221 of FIG. If the thread CL24 fails to acquire a response for 3 seconds, the process proceeds to step S604.
(Step S604) The thread CL24 closes the socket generated in Step S217. Thereafter, the process proceeds to Step SS239.
(Step S605) The FB session CL23 generates a program (doRetry) for performing fallback. Thereafter, the process proceeds to step S304.

  Thus, according to the present embodiment, the FB source interface 151-i performs the first communication (for example, Wi-Fi). The FB destination interface 151-k performs second communication (for example, LTE). The memory | storage part 14 memorize | stores FB original header information which is header information of the communication data acquired using 1st communication. The proxy unit P1 acquires FB destination header information that is header information of communication data acquired using the second communication. The proxy unit P1 compares the FB source header information and the FB destination header information, and controls switching between the first communication and the second communication for a part or all of the communication based on the comparison result. Thereby, the communication apparatus 1 can control switching of a radio link appropriately. For example, the communication device 1 can prevent data inconsistency by combining data acquired using the first communication and data acquired using the second communication by fallback.

Further, according to the present embodiment, the proxy unit P1 performs the first communication and the second communication for part or all of the communication when at least a part of the FB source header information and the FB destination header information do not match. It is determined to stop switching. That is, the communication device 1 stops the fallback.
When the FB destination header information indicates redirection, the proxy unit P1 acquires the FB destination header information from the redirection destination, and based on the comparison result between the acquired FB destination header information and the FB source header information, For some or all, switching between the first communication and the second communication is controlled. As a result, the communication device 1 can perform fallback when the same header information can be acquired even when redirected during fallback, that is, when the content is finally the same.

  Further, according to the present embodiment, the storage unit 14 stores content (also referred to as acquired content) acquired using the first communication among the contents provided to the communication device 1. When at least a part of the FB source header information and the FB destination header information match, the proxy unit P1 determines to switch the first communication and the second communication for a part or all of the communication. The proxy unit P1 acquires content other than the acquired content (also referred to as non-acquired content) from the content using the second communication, and combines the acquired content and the unacquired content.

  Further, according to the present embodiment, the proxy unit P1 determines whether or not a condition (switching condition) for performing a single fallback from the first communication to the second communication is satisfied, by a predetermined session (a series of communication). The switching from the first communication to the second communication is controlled for each session based on the determination result. Thus, since the communication apparatus 1 performs single fallback control for each session, it is possible to appropriately control switching of radio links.

  For example, when the response to the connection request using the first communication cannot be acquired for a predetermined time or longer (for example, when the session times out), the proxy unit P1 determines that the condition for performing the single fallback is satisfied. In addition, when the proxy unit P1 cannot acquire information that can identify the transmission source of communication data acquired using the first communication for a predetermined time or longer (for example, when the name resolution process times out), the proxy unit P1 It may be determined that the conditions for performing the back are satisfied. As a result, the communication device 1 has a certain session in an environment in which a specific server or communication path is down, or in an environment in which a delay in response equal to or greater than a threshold value determined to perform single fallback in a specific network occurs. It is possible to suppress switching to all other communications (communication with which connection is likely to be successful) simply by being unable to connect.

  In addition, the proxy unit P1 changes the timeout time (predetermined time) according to the number of FB sessions (the number switched from the first communication to the second communication). For example, the proxy unit P1 increases the timeout time according to the number of single fallbacks. Thereby, the communication apparatus 1 can control so that it may become difficult to fall back gradually from two to two rather than two according to the number of FB sessions. Therefore, for example, when the connection environment of Wi-Fi communication being used is constantly delayed, the communication device 1 can easily prevent all communication from being fallbacked.

  Further, the proxy unit P1 may linearly increase the timeout time according to the number of FB sessions. Further, the proxy unit P1 may increase the timeout time nonlinearly according to the number of FB sessions. As described above, the communication device 1 can adjust the degree of difficulty in gradually falling back when performing control so as to make it difficult to gradually fall back according to the number of FB sessions.

  Note that the proxy unit P1 may perform control so as to decrease the timeout time according to the number of FB sessions. Thereby, the communication apparatus 1 can also be controlled so as to easily fall back gradually according to the number of FB sessions.

  Further, according to the present embodiment, the proxy unit P1 controls switching between the first communication and the second communication for each predetermined session (a series of communications), and switches from the first communication to the second communication. Count the number of sessions (number of FB sessions). The proxy unit P1 prioritizes the first communication according to a predetermined rule, and prioritizes the second communication when the counted number of FB sessions exceeds the allowable value (transitions to the forced fallback mode). In this way, the communication device 1 makes a transition to the forced fallback mode, thereby eliminating the cost of trying to establish communication with an unnecessary link, and can immediately perform good communication. The predetermined rule is, for example, a method in which the first communication is given priority in a predetermined state (default state or normal state). According to the present embodiment, the first communication and the second communication have different communication interfaces. The proxy unit P1 controls switching between the FB source interface 151-i for the first communication and the FB destination interface 151-k for the second communication.

(Second Embodiment)
The communication device 1 (proxy unit P1) may perform failback during the session, that is, before completion of communication at the FB destination. In that case, the communication apparatus 1 may determine whether or not to perform a failback by performing a header comparison process.

(Third embodiment)
In each said embodiment, the communication apparatus 1 (proxy part P1) may compare the one part or all part of the header information of the data part provided. For example, an HTTP packet includes HTTP data as a data portion after an IP header or a TCP header. For example, the HTTP data is HTML information.
In this case, for example, the communication device 1 can acquire data of 200 bytes or less by specifying “Range: bytes = −200” in the HTTP header field in the wireless link L2. For example, when the data is HTML, the data before 200 bytes includes part or all of the HTML header information. The communication device 1 may perform header comparison processing by comparing part or all of the acquired HTML header information with part or all of the HTML header information acquired using the radio link L1. Good.

(Fourth embodiment)
The communication device 1 (proxy unit P1) may consider the timeout time of the application in determining whether to perform fallback (including header comparison processing). For example, the communication device 1 may determine that the fallback is not performed when the time of the header comparison process or the RD destination information acquisition process approaches the timeout time of the application.

Note that a part of the communication device 1 in the above-described embodiment may be realized by a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by the computer system and executed. Here, the “computer system” is a computer system built in the communication apparatus 1 and includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In this case, a volatile memory inside a computer system that serves as a server or a client may be included that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.
Moreover, you may implement | achieve part or all of the communication apparatus 1 in embodiment mentioned above as integrated circuits, such as LSI (Large Scale Integration). Each functional block of the communication device 1 may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integrated circuit technology that replaces LSI appears due to the advancement of semiconductor technology, an integrated circuit based on the technology may be used.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

  DESCRIPTION OF SYMBOLS 1 ... Communication apparatus, AP1 ... Access point, BS1 ... Base station apparatus, Sv101, Sv102, Sv103, Sv104 ... Server apparatus, 11 ... Input part, 12 ... Output part, 13 ... Control part, 14 ... Storage part, 15 ... Communication part, 131 ... Application part, P1 ... Proxy part, 151-1 to 151-N ... Interface, 152 ... Signal strength detection unit, P111 ... session management unit, P112 ... DNS management unit, P113 ... throughput acquisition unit, P114 ... capacity information acquisition unit, P121 ... signal strength acquisition unit, P122 ... Time measuring unit, P123 ... AP information acquisition unit, P124 ... Communication method information acquisition unit, P125 ... Position information acquisition unit, P131 ... Header information acquisition unit, P132 Redirection information acquisition unit, P14 ··· IF selection unit, P15 ··· data synthesis section

Claims (11)

A first communication unit for performing first communication;
A second communication unit for performing second communication;
Whether or not the condition for switching from the first communication to the second communication is satisfied is determined for each predetermined series of communications, and based on the determination result, for each series of communications, A selection unit that controls switching to the second communication;
A counting unit that counts the number of the series of communications that are switched from the first communication to the second communication;
Equipped with a,
The selection unit includes:
Priority is given to the first communication, and when the number of the series of communications counted by the counting unit exceeds a threshold, the second communication is given priority over the series of communications thereafter.
Communication equipment. The selection unit includes:
When a response to the connection request using the first communication cannot be obtained for a predetermined time or more, it is determined that the switching condition is satisfied.
The communication apparatus according to claim 1. The selection unit includes:
When the information that can identify the transmission source of the communication data acquired using the first communication cannot be acquired for a predetermined time or more, it is determined that the switching condition is satisfied.
The communication apparatus according to claim 1. The selection unit includes:
The predetermined time is changed according to the number of switching from the first communication to the second communication.
The communication apparatus as described in any one of Claim 2 or 3. The selection unit includes:
The predetermined time is increased according to the number of switching from the first communication to the second communication.
The communication apparatus according to claim 4. The selection unit includes:
The predetermined time is increased linearly according to the number of times the first communication is switched to the second communication.
The communication device according to claim 5. The selection unit includes:
The predetermined time is increased nonlinearly according to the number of switching from the first communication to the second communication.
The communication device according to claim 5. The first communication and the second communication have different logical or physical communication interfaces,
The selection unit includes:
Controlling switching from the first communication interface to the second communication interface;
The communication apparatus as described in any one of Claim 1 to 7 . In a communication method in a communication device,
The selection part
A determination process for determining whether a condition for switching from the first communication to the second communication is satisfied for each predetermined series of communication;
A selection process for controlling switching from the first communication to the second communication for each series of communication based on the determination result of the determination;
The counting unit
A counting process for counting the number of the series of communications being switched from the first communication to the second communication;
I have a,
In the selection process,
Priority is given to the first communication, and when the number of the series of communications counted in the counting process exceeds a threshold, the second communication is given priority over the series of communications thereafter.
Communication method. In the computer of the communication device,
A determination procedure for determining whether a condition for switching from the first communication to the second communication is satisfied for each predetermined series of communication;
A selection procedure for controlling switching from the first communication to the second communication for each series of communications based on the judgment result of the judgment;
A counting procedure for counting the number of the series of communications being switched from the first communication to the second communication;
Was executed,
In the selection procedure,
Priority is given to the first communication, and when the number of the series of communications counted in the counting procedure exceeds a threshold, the second communication is given priority over the series of subsequent communications.
Communication program. Whether or not the switching condition from the first communication to the second communication is satisfied is determined for each predetermined series of communication, and based on the determination result, the first communication to the second communication for each series of communication. a selecting unit for controlling the switching of the communication,
A counting unit that counts the number of the series of communications that are switched from the first communication to the second communication;
Equipped with a,
The selection unit includes:
Priority is given to the first communication, and when the number of the series of communications counted by the counting unit exceeds a threshold, the second communication is given priority over the series of communications thereafter.
Processor.

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