JP2016163063A - Communication apparatus and communication control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication apparatus etc. capable of adjusting maximum transfer amount suitable for a communication network of a receiver at a communication apparatus.SOLUTION: A radio terminal has a first determination section that determines whether or not the number of re-transmissions of a packet accompanying a discard of a packet during a TCP (transmission control protocol) transfer is within a re-transmission threshold level or more. The radio terminal further has a first adjustment section that, when the number of re-transmission is the re-transmission threshold level or more, adjusts the size of present MTU setting in a direction to reduce by multiplying an adjustment amount of reduction ratio to the present MTU setting; and a first control unit that sets the adjusted MTU.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a communication device and a communication control program.

  For example, in a network defined by IEEE (The Institute of Electrical and Electronics Engineers, Inc.) or the like, a maximum transfer unit (MTU) that can transfer data is defined. In a network, for example, when data is transferred between a mobile phone and a server, data exceeding the MTU is discarded and cannot be transferred.

  In addition, as a method for determining the MTU of a network using a plurality of physical networks, RFC (Request for Comment) 1191 of IETF (Internet Engineering Task Force) is defined.

  However, some communication networks cannot use the functions of RFC 1191 from the viewpoint of security and the like. A method for automatically adjusting the packet size based on statistical information and route information in the network has also been proposed.

JP 2003-218840 A JP-T-2007-527179 JP 2008-227855 A

  A communication network of a communication carrier that accommodates a communication device such as a smartphone may have different MTUs set for each communication carrier or communication type. For example, there is no problem between the communication networks of Japanese carriers, but when using the communication network of overseas carriers for overseas roaming etc., the MTU is different. Transfer may not be possible.

  However, in the communication apparatus, since the MTU of the communication network used for overseas roaming or the like is unknown, the size of the MTU suitable for the communication network cannot be dynamically adjusted. As a result, the communication device cannot adjust the size of the MTU (maximum transfer unit) suitable for the communication network and cannot communicate with the communication network.

  An object of one aspect is to provide a communication device and a communication control program that can adjust a maximum transfer unit suitable for a communication network on the communication device side.

  One communication device includes a transmission unit, a determination unit, and an adjustment unit. The transmission unit transmits data in units of a predetermined maximum transfer amount. The determination unit is configured such that when the transmission unit transfers data in units of the predetermined maximum transfer amount, the number of data retransmissions executed when the data transfer amount exceeds the predetermined maximum transfer amount is a predetermined number or more. It is determined whether or not there is. The adjustment unit adjusts the predetermined maximum transfer amount so as to decrease when the number of times of data retransmission is equal to or greater than the predetermined number.

  The maximum transfer unit suitable for the communication network can be adjusted on the communication device side.

FIG. 1 is an explanatory diagram illustrating an example of a wireless terminal according to the first embodiment. FIG. 2 is an explanatory diagram illustrating an example of a measurement table for TCP. FIG. 3 is a sequence diagram illustrating an example of processing operations of the wireless terminal and the server related to the first MTU adjustment processing. FIG. 4 is a flowchart showing an example of the processing operation of the processor of the wireless terminal involved in the table setting process. FIG. 5 is a flowchart illustrating an example of the processing operation of the processor of the wireless terminal related to the first MTU adjustment processing. FIG. 6 is an explanatory diagram of an example of a wireless terminal according to the second embodiment. FIG. 7 is an explanatory diagram showing an example of a measurement table for UDP. FIG. 8 is a sequence diagram illustrating an example of processing operations of the wireless terminal and the server related to the second MTU adjustment processing. FIG. 9 is a flowchart illustrating an example of the processing operation of the processor of the wireless terminal related to the second MTU adjustment processing. FIG. 10 is an explanatory diagram illustrating an example of an information processing apparatus that executes a communication control program.

  Hereinafter, embodiments of a communication device and a communication control program disclosed in the present application will be described in detail based on the drawings. The disclosed technology is not limited by the present embodiment. Moreover, you may combine suitably each Example shown below in the range which does not cause contradiction.

  FIG. 1 is an explanatory diagram illustrating an example of a wireless terminal 1 according to the present embodiment. A wireless terminal 1 shown in FIG. 1 includes a wireless unit 11, a display unit 12, a touch sensor 13, an audio input / output unit 14, a microphone 15, a speaker 16, a ROM (Read Only Memory) 17, a RAM ( Random Access Memory) 18 and a processor 19.

  The wireless unit 11 is a part that controls wireless communication of the wireless terminal 1. The wireless unit 11 has a function of executing packet communication using, for example, TCP (Transmission Control Protocol) or UDP (User Datagram Protocol). The display unit 12 is an output interface that displays various types of information. The touch sensor 13 is an input interface for inputting various information. The audio input / output unit 14 is connected to the microphone 15 and the speaker 16, inputs an acoustic signal from the microphone 15, and outputs an acoustic signal from the speaker 16.

  The ROM 17 is an area for storing various information such as a communication control program. The RAM 18 has an area for storing various information, and includes, for example, a measurement table 30. The measurement table 30 is a table that stores measurement reference values for TCP used when adjusting an MTU suitable for a communication network for TCP communication, which will be described later. FIG. 2 is an explanatory diagram showing an example of the TCP measurement table 30. The measurement table 30 in FIG. 2 manages an MTU value 33, a retransmission threshold 34, a unit time 35, an adjustment amount (decrease rate) 36, and an update date 37 in association with each communication carrier 31 and communication bearer 32. . The communication carrier 31 is an ID for identifying the communication carrier of the communication network. The communication bearer 32 is a communication type to be used, for example, LTE (Long Term Evolution), GSM (Global System for Mobile Communications (registered trademark)), WCDMA (Wideband Code Division Multiple Access (registered trademark)), and Wi-Fi (Wireless). Fidelity (registered trademark)). The MTU value 33 is the MTU value currently set. The MTU value 33 is an MTU value corresponding to a communication bearer at the time of initial setting. The retransmission threshold 34 is a threshold for the number of packet retransmissions for determining a TCP transfer error, which will be described later. The unit time 35 is the monitoring time of the monitoring timer for determining a TCP transfer error. The adjustment amount 36 is a ratio of the MTU value for adjusting the MTU value in the decreasing direction. The update date and time 37 is the date and time when the contents of the measurement table 30 are updated.

  The processor 19 refers to the measurement table 30, the carrier 31 is "Company D", the communication bearer 32 is "LTE", the MTU value 33 is "1400" bytes, the retransmission threshold 34 is "3", and the unit time 35 is It is recognized that “60 seconds” and the adjustment amount (reduction ratio) 36 are “10%” and the like.

  The processor 19 is a part that controls the entire wireless terminal 1. The processor 19 reads the communication control program stored in the ROM 17 and configures various processes as functions based on the read communication control program. The processor 19 includes a recognition unit 21, a first determination unit 22, a first adjustment unit 23, and a first control unit 24 as functional configurations. The recognizing unit 21 recognizes the communication carrier and the communication type from the located area information during communication. The first determination unit 22 determines a TCP transfer error for the communication network of the communication destination. If the first adjustment unit 23 determines that the TCP transfer error has occurred, the first adjustment unit 23 adjusts the currently set MTU value. The first control unit 24 controls the entire processor 19.

  The first control unit 24 transmits a packet with the MTU value being set to the server 2 in the communication network through the wireless unit 11. After transmitting a packet to the server 2, the first control unit 24 recognizes that the packet is discarded when a response packet (ACK) to the transmission packet is not received by TCP, requests packet retransmission, and retransmits the packet. Note that the retransmission mechanism by packet discard is defined in RFC2018 (TCP Selective Acknowledgment Options). The first control unit 24 uses, for example, the mechanism of RFC2018.

  The first control unit 24 determines whether or not the measurement table 30 corresponding to the communication carrier and the communication bearer recognized by the recognition unit 21 is in the RAM 18. When there is a measurement table 30 corresponding to the recognized communication carrier and communication bearer, the first control unit 24 determines the measurement reference value (MTU value 33, retransmission threshold 34, unit time 35, and adjustment amount from the corresponding measurement table 30. 36) is read and set.

  When the first control unit 24 refers to the retransmission threshold 34 and the unit time 35 within the set measurement reference value and detects the first packet retransmission due to packet discard during communication with the server 2, monitoring is performed (not shown). The timer timing operation is started, and the number of retransmissions of the packet is incremented by +1. Then, the first control unit 24 increments the number of retransmissions by +1 each time a retransmission is detected during the monitoring time.

  The first determination unit 22 determines whether or not the number of packet retransmissions within a unit time is greater than or equal to a retransmission threshold. When it is determined that the number of retransmissions is equal to or greater than the retransmission threshold, the first determination unit 22 determines a TCP transfer error.

  If the first adjustment unit 23 determines that the TCP transfer error has occurred, the first adjustment unit 23 refers to the MTU value 33 and the adjustment amount 36 within the set measurement reference value, and the current MTU value α * adjustment amount (decrease rate: 10%) β An adjusted MTU value is calculated. That is, the adjusted MTU value decreases at a rate of 10% from the current MTU value. Note that the adjustment amount can be appropriately changed.

  The first control unit 24 determines whether or not the calculated adjusted MTU value has fallen below the MTU lower limit value. The MTU lower limit value is a lower limit value of the settable MTU value. When the adjusted MTU value does not fall below the MTU lower limit value, the first control unit 24 sets the adjusted MTU value as the current MTU value and updates the current MTU value 33 in the measurement table 30 to the adjusted MTU value. The first control unit 24 does not set the adjusted MTU value when the adjusted MTU value falls below the MTU lower limit value.

  Next, the operation of the wireless terminal 1 according to the first embodiment will be described. FIG. 3 is a sequence diagram illustrating an example of processing operations of the wireless terminal 1 and the server 2 related to the first MTU adjustment processing. The wireless terminal 1 shown in FIG. 3 transmits a packet to which the sequential number is added with the current MTU value to the server 2 during TCP communication with the server 2 (step S11). When there is no packet response from the server 2, the wireless terminal 1 recognizes packet discard based on the sequential number (step S12).

  When the wireless terminal 1 recognizes the packet discard, the wireless terminal 1 detects the packet retransmission (step S13) and increments the number of retransmissions by +1. Then, the wireless terminal 1 transmits the packet with the current MTU value to the server 2 in response to the packet retransmission (step S14).

  Furthermore, when there is no packet response from the server 2, the wireless terminal 1 recognizes packet discard based on the sequential number (step S15). When the wireless terminal 1 recognizes the packet discard, the wireless terminal 1 detects packet retransmission (step S16), and increments the number of retransmissions by +1. Furthermore, the wireless terminal 1 transmits the packet with the current MTU value to the server 2 in response to the packet retransmission (step S17).

  If the number of retransmissions is equal to or greater than the retransmission threshold (step S18), the wireless terminal 1 determines that a TCP transfer error has occurred (step S19). The wireless terminal 1 executes MTU adjustment processing for adjusting the MTU value in the decreasing direction by the current MTU value α * adjustment amount (decrease rate: 10%) β (step S20). As a result, the wireless terminal 1 sets the MTU value adjusted in the decreasing direction, and can secure TCP packet communication with the server 2 with the set adjusted MTU value.

  FIG. 4 is a flowchart showing an example of the processing operation of the processor 19 in the wireless terminal 1 related to the table setting process. The table setting process shown in FIG. 4 is a process for setting the TCP measurement table 30 corresponding to the communication carrier and communication bearer of the communication destination, and setting the measurement reference value in the set measurement table 30.

  In FIG. 4, the processor 19 determines whether or not a change in the communication bearer has been detected (step S21). The change of the communication bearer is, for example, a change from LTE to WCDMA within the same communication carrier, for example, a change from LTE of B company to WCDMA of D company, and the like. When the change of the communication bearer is detected (Yes at Step S21), the recognition unit 21 in the processor 19 recognizes the communication carrier and the communication bearer of the communication network from the location information (Step S22).

  The first control unit 24 in the processor 19 determines whether or not the measurement table 30 corresponding to the recognized communication carrier and communication bearer is in the RAM 18 (step S23). When there is a measurement table 30 corresponding to the communication carrier and the communication bearer (Yes at Step S23), the first control unit 24 sets a measurement reference value in the measurement table 30 (Step S24), and will be described later with reference to FIG. The first MTU adjustment process shown in FIG. 4 is executed (step S25), and the processing operation shown in FIG.

  If the measurement table 30 corresponding to the recognized communication carrier and communication bearer is not in the RAM 18 (No in step S23), the first control unit 24 creates a new measurement table 30 corresponding to the recognized communication carrier and communication bearer. Is generated (step S26). It is assumed that an initial value is set as the measurement reference value in the new measurement table 30. Further, after generating the new measurement table 30, the first control unit 24 sets the measurement reference value of the new measurement table 30 (step S27), and executes the first MTU adjustment process. The process proceeds to S25.

  When the processor 19 has not detected a change in the communication bearer (No at Step S21), the processor 19 determines whether or not packet communication is being performed (Step S28). When the packet communication is being performed (Yes at Step S28), the recognizing unit 21 proceeds to Step S22 in order to recognize the communication carrier and the communication bearer from the location information. When the packet communication is not in progress (No at Step S28), the processor 19 ends the processing operation shown in FIG.

  The processor 19 that executes the table setting process shown in FIG. 4 recognizes the communication carrier and the communication bearer from the location information, and if the measurement table 30 corresponding to the recognized communication carrier and the communication bearer is in the RAM 18, The measurement reference value in the measured table 30 is set. As a result, the wireless terminal 1 can set a measurement reference value for adjusting the MTU value suitable for the communication network of the communication destination.

  If the measurement table 30 corresponding to the recognized communication carrier and communication bearer is not in the RAM 18, the processor 19 generates a new measurement table 30 and sets a measurement reference value in the new measurement table 30. As a result, the wireless terminal 1 can set a measurement reference value for adjusting the MTU value suitable for the communication network of the communication destination.

  FIG. 5 is a flowchart illustrating an example of processing operation of the processor 19 of the wireless terminal 1 related to the first MTU adjustment processing. The first MTU adjustment process shown in FIG. 5 is a process for adjusting the size of the MTU currently being set when it is determined that a TCP transfer error has occurred.

  In FIG. 5, the first control unit 24 in the processor 19 of the wireless terminal 1 determines whether or not packet communication by TCP communication with the server 2 has been started (step S31). When packet communication is started (Yes at Step S31), the first control unit 24 determines whether or not retransmission of a packet due to packet discard is detected (Step S32).

  When detecting the retransmission of the packet (Yes at Step S32), the first determination unit 22 determines whether the data size of the discarded packet satisfies the first condition (Step S33). The first condition is a condition for determining whether or not the data size of the discarded packet is larger than the lower limit value of the MTU value and smaller than the currently set MTU value. Note that the first control unit 24 recognizes the data size of the discarded packet.

  When the data size of the discarded packet satisfies the first condition (Yes at Step S33), the first determination unit 22 determines whether the monitoring timer is counting time (Step S34). If the monitoring timer is not counting time (No at Step S34), the first determination unit 22 starts the monitoring timer (Step S35). After starting the monitoring timer, the first determination unit 22 clears the number of retransmissions (step S36) and increments the number of retransmissions by +1 (step S37).

  The first determination unit 22 increments the number of retransmissions by +1, and then refers to the retransmission threshold 34 and the unit time 35 in the measurement table 30 being set to determine whether the number of retransmissions is equal to or greater than the retransmission threshold ( Step S38). The first adjusting unit 23 in the processor 19 calculates the adjusted MTU value with the current MTU value α * adjustment amount (decrease rate: 10%) β when the number of retransmissions is equal to or greater than the retransmission threshold (Yes at Step S38) ( Step S39). As a result, the adjusted MTU value is 10% smaller than the current MTU value.

  After calculating the adjusted MTU value, the first control unit 24 determines whether or not the adjusted MTU value is below the MTU lower limit value (step S40). When the adjusted MTU value does not fall below the MTU lower limit value (No at Step S40), the first control unit 24 sets the calculated adjusted MTU value (Step S41).

  When the first determination unit 22 does not start the packet communication (No at Step S31), the first determination unit 22 ends the processing operation illustrated in FIG. The first determination unit 22 detects packet retransmission when no packet retransmission is detected (No at Step S32) or when the data size of the discarded packet does not satisfy the first condition (No at Step S33). In order to determine whether or not, the process proceeds to step S32. If the monitoring timer is counting time (Yes at Step S34), the first determination unit 22 proceeds to Step S37 to increment the number of retransmissions by +1.

  If the number of retransmissions is not equal to or greater than the retransmission threshold (No at Step S38), the first control unit 24 determines whether or not the monitoring timer detects a time-up (Step S42). When the monitoring timer expires (Yes at Step S42), the first control unit 24 clears the timing operation of the monitoring timer (Step S43), and ends the processing operation illustrated in FIG. Furthermore, when the monitoring timer has not timed up (No at Step S42), the first control unit 24 proceeds to Step S32 in order to determine whether or not packet retransmission has been detected. When the adjusted MTU value falls below the MTU lower limit value (Yes at Step S40), the first control unit 24 proceeds to Step S43 in order to clear the timing operation of the monitoring timer without setting the adjusted MTU value.

  The processor 19 that executes the first MTU adjustment process shown in FIG. 5 determines that a TCP transfer error occurs when the number of packet retransmissions is greater than or equal to the retransmission threshold within a unit time, and adjusts the decrease rate to the currently set MTU value. Multiply the amount to calculate the adjusted MTU value. As a result, even when a TCP transfer error occurs, it is possible to reduce the TCP transfer error by reducing the currently set MTU value.

  After determining that the TCP transfer error has occurred, the processor 19 multiplies the currently set MTU value by the adjustment amount of the reduction rate, and sets the calculated adjusted MTU value when the calculated adjusted MTU value does not fall below the MTU lower limit value. As a result, the wireless terminal 1 can ensure packet communication with the server 2 based on the adjusted MTU value.

  Further, the processor 19 updates the calculated adjusted MTU value in the measurement table 30 when the adjusted MTU value does not fall below the MTU lower limit value. As a result, since the wireless terminal 1 updates the adjusted MTU value in the measurement table 30, the next MTU adjustment can be smoothly realized.

  The processor 19 does not set the calculated adjusted MTU value when the calculated adjusted MTU value falls below the MTU lower limit value. As a result, the wireless terminal 1 can prevent TCP transfer errors due to readjustment of the MTU value.

  The processor 19 repeatedly executes the first MTU adjustment process again and gradually adjusts the MTU value even if the TCP transfer error cannot be resolved with the adjusted MTU value calculated by one first MTU adjustment process. Thus, the TCP transfer error can be surely solved.

  When the number of packet retransmissions is equal to or greater than the retransmission threshold, the wireless terminal 1 according to the first embodiment calculates the adjusted MTU value by multiplying the currently set MTU value by the adjustment amount of the decrease rate, and calculates the calculated adjusted MTU value. Set. As a result, even when a TCP transfer error occurs, the wireless terminal 1 can resolve the TCP transfer error by reducing the currently set MTU value and secure packet communication with the server 2. That is, the MTU value suitable for the other party's communication network can be adjusted on the wireless terminal 1 side. For example, the wireless terminal 1 can eliminate the TCP transfer error even during overseas roaming and can secure overseas roaming communication.

  Even when the wireless terminal 1 transmits a packet of a size that does not permit packet transfer, if the retransmission that occurs at that time is repeatedly performed, the MTU value set in the terminal itself is reduced to ensure that the packet is transmitted. Can be transmitted. That is, even when the MTU value of the switching destination communication network is small, the MTU value is reduced to a transferable size, so that packet transmission can be realized with certainty.

  In the wireless terminal 1 of the first embodiment, when the adjusted MTU value is below the MTU lower limit value, the calculated adjusted MTU value is not set. However, when the adjusted MTU value is lower than the MTU lower limit value, the adjustment amount of the current MTU value decrease rate may be reduced, and the adjustment amount may be adjusted so that the adjusted MTU value does not fall below the MTU lower limit value.

  In the wireless terminal 1, the MTU value that is currently set is multiplied by the reduction rate adjustment amount to decrease the MTU value. However, the MTU value is multiplied by the increase rate adjustment amount to increase the MTU value. Anyway.

  When the wireless terminal 1 detects retransmission of a packet as the number of retransmissions, the retransmission number is incremented by +1. However, when the retransmission request before the packet retransmission is detected or when packet discard is detected, the number of retransmissions is increased. May be incremented.

  In the first embodiment, the case of adjusting the MTU size of the TCP communication between the wireless terminal 1 and the server 2 has been exemplified. However, the present invention is applicable to the UDP communication, and the embodiment in that case The second embodiment will be described below.

  FIG. 6 is a block diagram illustrating an example of the wireless terminal 1A according to the second embodiment. The same components as those of the wireless terminal 1 according to the first embodiment are denoted by the same reference numerals, and the description of the overlapping configuration and operation is omitted. A wireless terminal 1A illustrated in FIG. 6 includes a processor 19A in addition to the wireless unit 11, the display unit 12, the touch sensor 13, the audio input / output unit 14, the microphone 15, the speaker 16, the ROM 17, and the RAM 18. The processor 19A has a main body control unit 50 and an application 60 as functional configurations.

  The RAM 18 includes a measurement table 40 that stores measurement reference values for UDP corresponding to communication carriers and communication bearers. FIG. 7 is an explanatory diagram showing an example of the measurement table 40 for UDP. The measurement table 40 illustrated in FIG. 7 manages an MTU value 43, an adjustment amount (increase rate) 44, and an update date 45 in association with each communication carrier 41 and communication bearer 42. The MTU value 43 is an MTU value currently set. The adjustment amount 44 is a rate of increasing the size of the currently set MTU. The update date and time 45 is the date and time when the contents of the measurement table 40 are updated. Note that the measurement reference values for UDP are the MTU value 43, the adjustment amount (increase rate) 44, and the like.

  The processor 19A refers to the measurement table 40 of FIG. 6, for example, the communication carrier 41 is “Company D”, the communication bearer 42 is “LTE”, the MTU value 43 is “1400” bytes, and the adjustment amount (increase rate) 44. "10%" etc. are recognized.

  The application 60 is an application that communicates with the server 2 in the communication network of the communication destination using, for example, UDP communication. The main body control unit 50 includes a recognition unit 21, a second adjustment unit 23A, and a second control unit 24A.

  The second control unit 24A recognizes the communication carrier and the communication type from the in-zone information in the packet during the UDP communication by the recognition unit 21, and the UDP measurement table corresponding to the recognized communication carrier and the communication type. The measurement reference value in 40 is read and set.

  When the second control unit 24A detects a packet transmission request from the application 60, the second control unit 24A determines whether the packet is larger than the MTU being set in the UDP communication. When the packet is larger than the MTU being set, the second control unit 24A divides the packet into units of MTU, and transmits the divided packet to the server 2 through the wireless unit 11.

  The application 60 determines whether an error response indicating an error in the data size is detected from the communication destination server 2. If the application 60 detects an error response, the application 60 determines that the UDP transfer error is caused by an illegal data size of packet division. If the application 60 determines that there is a UDP transfer error, the application 60 notifies the main body control unit 50 of an MTU adjustment request.

  When detecting the MTU adjustment request, the second adjustment unit 23A refers to the MTU value 43 and the adjustment amount 44 within the measurement reference value being set, and adjusts the adjustment amount (increase rate: 10%) to the currently set MTU value. ) To calculate an adjusted MTU value. That is, the second adjustment unit 23A increases the ratio from the currently set MTU value at a rate of 10%.

  The second control unit 24A determines whether or not the calculated adjusted MTU value exceeds the MTU upper limit value. The MTU upper limit value is an upper limit value of the settable MTU value. When the calculated adjusted MTU value does not exceed the MTU upper limit value, the second control unit 24A sets the calculated adjusted MTU value. Furthermore, when the calculated adjustment MTU value does not exceed the MTU upper limit value, the second control unit 24A updates the calculated adjustment MTU value in the measurement table 40 being set. When the calculated adjusted MTU value exceeds the MTU upper limit value, the second control unit 24A does not set the calculated adjusted MTU value.

  Next, the operation of the wireless terminal 1A according to the second embodiment will be described. When the wireless terminal 1A recognizes the communication carrier and the communication bearer, the wireless terminal 1A executes the table setting process shown in FIG. 4, and reads and sets the measurement reference value in the measurement table 40 corresponding to the communication carrier and the communication bearer. is there. FIG. 8 is a sequence diagram illustrating an example of processing operations of the wireless terminal 1A and the server 2 related to the second MTU adjustment processing according to the second embodiment. The application 60 in the wireless terminal 1A shown in FIG. 8 notifies the main body control unit 50 of a UDP communication packet transmission request (step S51). The main body control unit 50 receives a packet transmission request (step S52), and divides the packet into MTU units (step S53). The main body control unit 50 transmits the divided data to the server 2 on the communication network side (step S54).

  When the server 2 receives a fragmented packet from the wireless terminal 1A (step S55), it is assumed that an error due to an illegal data size of the fragmented packet is detected (step S56). When the server 2 detects an error due to an illegal data size, the server 2 transmits an error response to the wireless terminal 1A (step S57).

  When receiving an error response from the server 2, the main body control unit 50 in the wireless terminal 1A notifies the application 60 of the error response (step S58). When the application 60 detects an error response (step S59), the application 60 recognizes that the error is caused by packet division (step S60), and notifies the main body control unit 50 of an MTU adjustment request (step S61). When detecting the MTU adjustment request, the main body control unit 50 executes a second MTU adjustment process for adjusting the currently set MTU value in the increasing direction (step S62).

  When the processor 19A that executes the second MTU adjustment process illustrated in FIG. 8 detects an error response due to an illegal UDP data size from the communication destination server 2, the processor 19A adjusts the currently set MTU value in an increasing direction. As a result, the wireless terminal 1A adjusts the size of the MTU currently being set in the increasing direction, so that the UDP transfer error can be eliminated.

  FIG. 9 is a flowchart illustrating an example of the processing operation of the processor 19A of the wireless terminal 1A related to the second MTU adjustment processing. The second MTU adjustment process shown in FIG. 9 is a process of adjusting the size of the MTU currently being set when it is determined that there is a UDP transfer error.

  In FIG. 9, the main body control unit 50 in the processor 19A in the wireless terminal 1A determines whether or not packet communication by UDP communication with the server 2 has been started (step S71). When the application 60 in the processor 19A starts packet communication (Yes at Step S71), the application 60 determines whether an error response is detected from the server 2 (Step S72).

  If the application 60 detects an error response (Yes at step S72), the application 60 determines whether the error response is a UDP transfer error due to an incorrect data size (step S73). Then, in the case of a UDP transfer error due to an illegal data size (Yes at Step S73), the application 60 notifies the main body control unit 60 of an MTU adjustment request. Then, in response to the MTU adjustment request, the second adjustment unit 23A in the main body control unit 50 calculates the adjusted MTU value using the currently set MTU value α * adjustment amount (increase rate: 10%) γ (step S21). S74). As a result, the adjusted MTU value can be 10% larger than the currently set MTU value.

  After calculating the adjusted MTU value, the second control unit 24A in the main body control unit 50 determines whether or not the adjusted MTU value exceeds the MTU upper limit value (step S75). When the adjusted MTU value does not exceed the MTU upper limit value (No at Step S75), the second control unit 24A sets the calculated adjusted MTU value (Step S76). The second control unit 24A updates the calculated adjusted MTU value as the MTU value 43 of the reference measurement value in the measurement table 40 being set.

  When the packet communication is not started (No at Step S71), the main body control unit 50 ends the processing operation illustrated in FIG. If no error response is detected from the server 2 (No at Step S72), the main body control unit 50 proceeds to Step S72 to determine whether an error response has been detected. When the content of the error response is not a UDP transfer error due to incorrect data size (No at Step S73), the main body control unit 50 proceeds to Step S72 to determine whether an error response has been detected. When the calculated adjusted MTU value exceeds the MTU upper limit value (Yes at Step S75), the second control unit 24A ends the processing operation illustrated in FIG. 9 without setting the adjusted MTU value.

  If the processor 19A that executes the second MTU adjustment process shown in FIG. 9 determines that there is a UDP transfer error, the processor 19A calculates the adjusted MTU value by multiplying the currently set MTU value by the adjustment amount of the increase rate. As a result, even if a UDP transfer error occurs, the UDP transfer error can be resolved by increasing the currently set MTU value.

  If the processor 19A determines that the UDP transfer error has occurred, the processor 19A multiplies the currently set MTU value by the adjustment amount of the increase rate, and if the calculated adjusted MTU value does not exceed the MTU upper limit value, sets the calculated adjusted MTU value. . As a result, the wireless terminal 1A can ensure packet communication by UDP with the server 2 based on the adjusted MTU value.

  Furthermore, when the adjusted MTU value does not exceed the MTU upper limit value, the processor 19A updates the calculated adjusted MTU value in the measurement table 40. As a result, since the wireless terminal 1A updates the adjusted MTU value in the measurement table 40, the next MTU adjustment can be performed smoothly.

  When the calculated adjusted MTU value exceeds the MTU upper limit value, the processor 19A does not set the calculated adjusted MTU value. As a result, the wireless terminal 1A can prevent a UDP transfer error due to the readjustment of the MTU value.

  When the wireless terminal 1A according to the second embodiment determines that the UDP transfer error is less than the currently set MTU value in the UDP communication, the wireless terminal 1A adjusts the currently set MTU value in the increasing direction. As a result, even when a UDP transfer error occurs, the wireless terminal 1A can eliminate the UDP transfer error by increasing the currently set MTU value, and can secure packet communication with the server 2. That is, the MTU value suitable for the other party's communication network can be adjusted on the wireless terminal 1A side. For example, the wireless terminal 1A can eliminate the UDP transfer error even during overseas roaming and can ensure overseas roaming communication.

  In the wireless terminal 1A of the second embodiment, when the adjusted MTU value exceeds the MTU upper limit value, the calculated adjusted MTU value is not set. However, when the adjusted MTU value exceeds the MTU upper limit value, the adjustment amount of the increase rate of the current MTU value may be reduced, and the adjustment amount may be adjusted so that the adjusted MTU value does not exceed the MTU upper limit value.

  In the wireless terminal 1A, the case where the MTU value is increased by multiplying the currently set MTU value by the increase rate adjustment amount is illustrated, but the MTU value is decreased by multiplying the MTU value by the decrease rate adjustment amount. Anyway.

  In the wireless terminal 1 of the first embodiment, the case where the size of the MTU for TCP communication is adjusted in order to eliminate the TCP transfer error is illustrated. However, the wireless terminal 1 may incorporate the function of the wireless terminal 1A of the second embodiment that adjusts the MTU size of UDP communication in order to eliminate the UDP transfer error.

  In addition, each component of each part illustrated does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each part is not limited to the one shown in the figure, and all or a part thereof may be functionally or physically distributed / integrated in arbitrary units according to various loads and usage conditions. Can be configured.

  Furthermore, various processing functions performed in each device are performed on a CPU (Central Processing Unit) (or a microcomputer such as an MPU (Micro Processing Unit), MCU (Micro Controller Unit), etc.) in whole or in part. You may make it perform. Various processing functions may be executed entirely or arbitrarily on a program that is analyzed and executed by a CPU (or a microcomputer such as an MPU or MCU) or hardware based on wired logic. Needless to say.

  By the way, the various processes described in the present embodiment can be realized by causing a program prepared in advance to be executed by a processor such as a CPU in the terminal device. Therefore, in the following, an example of a terminal device that executes a program having the same function as the above embodiment will be described. FIG. 10 is an explanatory diagram illustrating an example of an information processing apparatus that executes a communication control program.

  The information processing apparatus 100 that executes the communication control program illustrated in FIG. 10 includes a communication unit 110, a ROM 120, a RAM 130, and a CPU 140. The communication unit 110, the ROM 120, the RAM 130, and the CPU 140 are connected via the bus 150.

  The ROM 120 stores in advance a communication control program that exhibits the same function as in the above embodiment. The ROM 120 stores a transmission program 120A, a determination program 120B, and an adjustment program 120C as communication control programs. Note that the communication control program may be recorded on a computer-readable recording medium with a drive (not shown) instead of the ROM 120. The recording medium may be, for example, a portable recording medium such as a CD-ROM, a DVD disk, or a USB memory, or a semiconductor memory such as a flash memory.

  Then, the CPU 140 reads the transmission program 120A from the ROM 120 and functions as the transmission process 130A on the RAM 130. Further, the CPU 140 reads the determination program 120B from the ROM 120 and functions as a determination process 130B on the RAM 130. The CPU 140 reads the adjustment program 120C from the ROM 120, and functions as the adjustment process 130C on the RAM 130.

  The CPU 140 transmits data in units of a predetermined maximum transfer amount through the communication unit 110. The CPU 140 determines whether or not the number of data retransmissions to be executed when the data transfer amount exceeds the predetermined maximum transfer amount when transferring the data in the predetermined maximum transfer amount unit is equal to or greater than a predetermined number of times. To do. The CPU 140 adjusts the predetermined maximum transfer amount so as to decrease when the number of data retransmissions is equal to or greater than the predetermined number. As a result, the maximum transfer amount suitable for the destination communication network can be adjusted on the information processing apparatus side.

1 wireless terminal 1A wireless terminal 19 processor 19A processor 21 recognition unit 22 first determination unit 23 first adjustment unit 23A second adjustment unit 24 first control unit 24A second control unit 30 measurement table 40 measurement table

Claims (4)

A transmission unit for transmitting data in a predetermined maximum transfer amount unit;
Whether or not the number of data retransmissions executed when the data transfer amount exceeds the predetermined maximum transfer amount when transferring data in the predetermined maximum transfer amount unit by the transmission unit is equal to or greater than a predetermined number. A determination unit for determining;
An adjustment unit that adjusts the predetermined maximum transfer amount in a direction of decreasing when the number of times of data retransmission is equal to or greater than the predetermined number of times. The adjustment unit is
When the data is transferred in units of the predetermined maximum transfer amount, if an error is detected in which the data transfer amount falls below the predetermined maximum transfer amount, the predetermined maximum transfer amount is adjusted to increase. The communication apparatus according to claim 1. A transmission unit for transmitting data divided into predetermined maximum transfer amount units;
A determination unit that determines whether or not an error is detected in which the data transfer amount falls below the predetermined maximum transfer amount when transferring data in the predetermined maximum transfer amount unit in the transmission unit;
And an adjustment unit that adjusts the predetermined maximum transfer amount in a direction to increase when an error lower than the predetermined maximum transfer amount is detected. In the information processing device,
Send data in a predetermined maximum transfer amount unit,
Determining whether or not the number of data retransmissions to be executed when the data transfer amount exceeds the predetermined maximum transfer amount when transferring data in the predetermined maximum transfer amount unit is greater than or equal to a predetermined number of times;
When the number of times of data retransmission is equal to or greater than the predetermined number of times, a communication control program that causes a process of adjusting the predetermined maximum transfer amount to increase is executed.

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