JP5839999B2 - Communication terminal device - Google Patents

Description

  The present invention relates to a communication terminal device, and in particular, communication for completing upload / download of a program file or data file with a transfer time limit set within the time limit using a “gap” time zone where the network is not congested. It relates to a terminal device.

  Currently, various types of data traffic such as browsing the web, sending and receiving streaming video, sending and receiving e-mails, and sending and receiving huge files are performed by wireless data communication terminals. Patent Document 1 and Non-Patent Document 1 focus on the degree of demand for real-time performance for data traffic, and set high priority for data traffic that requires high real-time performance, so that radio resources ( A technique for allocating time, frequency, power) is disclosed.

  However, in these prior arts, even if the data traffic does not require real-time property, radio resources are always allocated even though the priority is low, so that radio resources are consumed. For this reason, from the viewpoint of a telecommunications carrier operating a radio access network, it is necessary to accommodate even urgent data traffic that does not require real-time performance despite congestion, and other data that requires real-time performance. It is not preferable because radio resources that are desired to be allocated to traffic are wasted.

  In response to such a technical problem, in Patent Document 2, for a terminal that transfers traffic with low real-time characteristics, the terminal itself searches for a time zone in which radio resources are available in an autonomous and distributed manner, and communication is performed in a time-sharing manner. Techniques to do are proposed.

  Further, Patent Document 3 proposes a system for transmitting and receiving imminent data traffic that does not require real-time performance in a time-sharing manner using a quiet time zone such as midnight when there is a sufficient radio resource.

JP 2003-169363 A JP 2010-226342 PR JP 2011-199592 PR

"Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 8: Medium Access Control (MAC) Quality of Service Enhancements," IEEE Std.802.11e, 2005

  Some files transferred over the network have a transfer deadline set even if it is not urgent. For example, drug price information used in medical institutions, pharmacies, and the like needs to be applied to a drug price calculation computer or the like on the switching date.

  Such a file with a transfer deadline set is notified with sufficient margin before the switching date, so it may be downloaded in advance and installed and used on the day of the switching date. However, considering the management of previously downloaded files and the risk of accidental installation prior to the switching date, it is desirable that the files be downloaded just before the switching date.

  On the other hand, if many users try to download files all at once, the network and server may become congested and the desired throughput cannot be obtained, and the file transfer may not be completed within the scheduled time limit. .

  However, in the above-described conventional technology, a file in which a transfer time limit is set cannot be transferred within the time limit only by communication in a time zone in which radio resources are available.

  An object of the present invention is to solve the above-described problems of the prior art, and to complete the transfer of a file with a transfer time limit set within the time limit using a “gap” time zone in which the network is not congested Is to provide.

  In order to achieve the above object, the present invention is characterized in that the following measures are taken in a wireless terminal apparatus that intermittently transfers a file with a transfer time limit set in units of blocks.

  (1) Session control means for controlling establishment and disconnection of a communication session in accordance with intermittent file transfer, transfer target determining means for determining a transfer target file, and a file for intermittent transfer of a transfer target file in the communication session Transfer means, throughput measurement means for measuring file transfer throughput, and back-off time calculation means for calculating back-off time for intermittent transfer each time a communication session is disconnected are provided.

  Then, the back-off time calculating means calculates a back-off time during which the file transfer can be completed by the transfer deadline based on the untransferred size of the file and the remaining time until the transfer deadline, and the session control means When the throughput falls below the reference threshold, the file is disconnected after waiting for the file transfer for one block, and reestablished every time the back-off time elapses.

  (2) The file transfer means is configured to continue file transfer in units of blocks if the actual throughput is equal to or greater than a predetermined threshold.

  (3) The throughput measuring means measures the throughput for each file transfer for one block.

  (4) A transfer target determining means for determining a file to be transferred every time file transfer for one block is completed is further provided.

  (5) The transfer target determining means preferentially targets a file with less remaining time until the transfer deadline.

  According to the present invention, the following effects are achieved.

  (1) Files with a transfer deadline set can be transferred only during the “clearance” time zone when the network is not congested, so transfer can be completed within the deadline without causing traffic concentration just before the transfer deadline. become able to. In addition, the intermittent transfer backoff time is calculated dynamically each time the communication session is disconnected due to a decrease in throughput, so even if the throughput fluctuates depending on the degree of congestion, files can be saved only with the length of the backoff time. Transfer can be completed within the transfer deadline.

  (2) If the throughput record is equal to or greater than a predetermined threshold, each file block is transferred continuously, not intermittently, so that free bandwidth can be used effectively.

  (3) Since the throughput is measured for each file transfer of one block, the backoff time can be accurately calculated even when the file is intermittently transmitted in units of blocks.

  (4) Since there is a transfer target determination means that determines the transfer target file for each file transfer for one block, another transfer file with a higher priority than this occurs during the transfer of one file. Then, it becomes possible to give priority to the transfer of another transfer file having a higher priority.

  (5) Since the transfer target determining means preferentially transfers a file with a shorter transfer time limit, efficient file transfer is possible.

It is the figure which expressed typically the file transfer method by this invention. It is a functional block diagram of a communication system to which the present invention is applied and its communication terminal device. It is the flowchart which showed operation | movement of one Embodiment of this invention. It is the time chart which showed the operation | movement of one Embodiment of this invention. It is the figure which showed the processing method of the interruption request.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic representation of a file transfer method according to the present invention, and a file with a transfer deadline set within the deadline only by communication using a “gap” time zone in which the network is not congested. Transfer can be completed.

  As shown in (a) of the figure, the file to be transferred is divided into multiple file blocks, and the transfer is repeated in units of file blocks, so that the file cannot be transferred in a day. The intermittent transfer is repeated over several days. Note that the priority of the transfer target file is set higher as the remaining time until the transfer deadline is smaller, and when multiple transfer target files are registered, transfer of the file block in order from the file with the highest priority Are executed sequentially.

  Further, in the present invention, when each file block is transferred, the throughput Tr is measured, and the throughput Tr is higher than a threshold Tr_th that is an index of the degree of congestion as before the time ts in FIG. If it is estimated that there is no congestion, the transfer in units of file blocks is repeated continuously instead of intermittently. On the other hand, if the measured throughput Tr is lower than the threshold value Tr_th and the network is estimated to be congested, such as after time ts, a predetermined back-off time is used to distribute the traffic in the time direction. Intermittent transfer with Tb in between is performed. However, the back-off time Tb is the amount of untransferred files (remaining amount) and the remaining time until the transfer deadline so that the file transfer can be completed within the time limit even during such intermittent transfer. It is optimized dynamically and adaptively based on the size of the file block.

  FIG. 2 is a functional block diagram showing the configuration of the main part of the communication system and the communication terminal device 1 to which the present invention is applied. Here, the configuration unnecessary for the description of the present invention is omitted. .

  The communication terminal device 1 according to the present invention establishes a communication session with the file server 2 via the network, and downloads and uploads the transfer file with the file server 2 in units of the file blocks.

  In the communication terminal device 1, the file information management unit 101 manages a file size and a transfer time limit, and a file block for dividing and transferring the file in units of blocks as information on the transfer target file. The file information of the download file can be acquired by inquiring the file server 2 in advance.

  The session control unit 102 controls establishment and disconnection of a communication session for performing file transfer with the file server 2. The transfer target determining unit 103 determines a transfer target file based on its priority. In this embodiment, the higher the priority is set for a file having a shorter remaining time until the transfer deadline.

  The throughput measuring unit 104 measures the throughput Tr during file transfer. As will be described in detail later, the back-off time calculation unit 105 determines the time after the time ts in FIG. In addition, the back-off time Tb when the file block is intermittently transferred when the throughput Tr decreases is calculated.

  The file transfer unit 106 uses the communication session established by the session control unit 102 to transfer each file block of the transfer file determined by the transfer target determination unit 103. The session control unit 102 maintains the established communication session if the throughput Tr at the time of file block transfer is higher than the threshold value Tr_th, and if it is lower than the threshold value Tr_th, waits for the completion of transfer of at least one file block. Then, after the back-off time Tb has elapsed, re-establishment is performed. Therefore, the file transfer according to the present invention is continuous transfer when the throughput Tr is higher than the threshold value Tr_th, and is intermittent transfer with the back-off time Tb interposed when the throughput Tr is lower than the threshold value Tr_th.

  FIG. 3 is a flowchart showing the operation of one embodiment of the present invention, and FIG. 4 is a time chart thereof.

  Here, the file transfer in which the communication terminal device 1 downloads the file stored in the file server 2 will be described as an example, but the file transfer in which the file stored in the communication terminal device 1 is uploaded to the file server 2 will be described. The same applies to the case.

  When the communication terminal device 1 is activated at time t1 in FIG. 4, the session control unit 102 accesses the file server 2 to establish a communication session in step S1. In step S <b> 2, the transfer target transfer file is determined by the transfer target determination unit 103. When a plurality of transfer files to be downloaded are registered, the transfer file with the highest priority among them is determined as the current download target.

  In step S3, a file block to be transferred this time is selected from the determined transfer file. In step S <b> 4, transfer of the selected one file block is started by the file transfer unit 106. The throughput measuring unit 104 measures the throughput Tr of the file transfer.

  At time t2, transfer of one file block at this time is completed, and when this is detected in step S5, the process proceeds to step S6 to determine disconnection. In step S6, the throughput Tr when the file block is downloaded is compared with a predetermined threshold value Tr_th. If Tr ≧ Tr_th, since it can be estimated that the network is not congested, the process proceeds to step S7 while maintaining the communication session, and it is determined whether or not an interrupt request for transfer of a new file has been made.

  If there is no interrupt request, the process advances to step S8 to determine whether or not the transfer of all the transfer files and their file blocks has been completed. Since it is determined that the process is not completed at first, the process returns to step S2 to determine the transfer file to be downloaded (step S2), select the file block (step S3), and transfer the file block (step S4). Repeated.

  Thereafter, if it is determined in step S6 that the throughput Tr is less than the threshold value Tr_th for the current file block whose transfer has been completed at time t3, the process proceeds to step S9. In step S9, the session control unit 102 disconnects the communication session. In step S10, the back-off time Tb until the next communication is started is calculated by the back-off time calculation unit 105 based on the following equations (1) and (2).

In the above formula (1), in the numerator of the first term on the right side, the remaining until the transfer deadline is obtained by subtracting the current time now from each transfer deadline Tdead (Fi) of multiple transfer target files Fi (i is a file identifier) The minimum value of time is calculated. In the denominator of the first term on the right side, the necessary number of intermittent transfers is obtained by dividing the total amount ΣVrest (Fi) of the size that needs to be downloaded after the current time now by the file block size dV. Therefore, in the first term on the right side, the required time that can be allowed for one block transfer is obtained in the remaining time until the transfer deadline.

  In the second term on the right side, the time required to transfer one file block is obtained by dividing the size dV of one file block by the threshold value Tr_th for interrupting the download due to a decrease in throughput. In the present embodiment, since the threshold value Tr_th is set to a value close to the practical minimum throughput, the required time is close to the longest time required for one file block transfer.

  In the above equation (1), the provisional value Tb_tmp of the back-off time Tb that can promise the transfer deadline is calculated by subtracting the second term from the first term on the right side. In the present embodiment, the back-off time Tb is further calculated by applying the provisional value Tb_tmp to the following equation (2).

  That is, the separately set lower limit value Tb_min of the back-off time is compared with the provisional value Tb_tmp. If Tb_min> Tb_tmp, the back-off time Tb is Tb_min and Tb_min + d (d is a separately determined range). As a random value between. On the other hand, if Tb_min> Tb_tmp is not satisfied, the back-off time Tb is obtained as a random value between Tb_min and Tb_tmp.

  Returning to FIG. 3, in step S11, it is determined whether or not the current back-off time Tb calculated as described above has timed out. At time t4 in FIG. 4, when the current back-off time Tb times out, Returning to step S1, the communication session is re-established, and as described above, determination of the transfer file to be downloaded, selection of the file block, and transfer of the file block are resumed.

  Similarly, for the file block that has been transferred at time t5, the session is disconnected when it is determined that the throughput Tr is below the threshold value Tr_th, and the backoff time Tb until the next communication is started is It is calculated in the same way. When the back-off time Tb times out at time t6, the communication session is re-established, and similarly to the above, determination of the transfer file to be downloaded, selection of the file block, and transfer of the file block are resumed.

  According to the present embodiment, a file with a transfer deadline set can be transferred only in a “gap” time zone where there is room for radio resources. You will be able to complete the transfer.

  In addition, if the throughput performance is equal to or greater than the predetermined threshold and it can be determined that there is sufficient room for radio resources, each file block is transferred continuously instead of intermittently. Become.

  If a new file interrupt request is detected in step S7, the process returns to step S2, and the transfer file to be downloaded is determined again. At this time, if the priority of the new file is lower than the priority of the file being transferred, the file transfer being executed is continued. On the other hand, if the priority of the new file is higher than the priority of the file being executed, as shown in FIG. 5, the current file transfer is interrupted and the transfer of the new file starts at time t8. When the transfer of the new file is completed at time t9, the interrupted file transfer is resumed.

  Also at this time, although illustration is omitted, if a decrease in throughput is detected in step S6 during transfer of a new file, the process proceeds to step S9 in the same manner as described above, the session is disconnected, and the back-off time Tb After the timeout, the session is reestablished and the file transfer is resumed.

  As described above, in this embodiment, the transfer target file is determined every time one file block is transferred, and therefore, when another transfer file with a higher priority than this occurs during transfer of one file. Therefore, it is possible to give priority to the transfer of the other transfer file having the higher priority.

  DESCRIPTION OF SYMBOLS 1 ... Communication terminal device, 2 ... File server, 101 ... File information management part, 102 ... Session control part, 103 ... Transfer object determination part, 104 ... Throughput measurement part, 105 ... Back-off time calculation part, 106 ... File transfer part

Claims (5)

In a wireless terminal device that intermittently transfers a file with a transfer deadline set in a predetermined block unit,
Session control means for controlling establishment and disconnection of a communication session in accordance with intermittent file transfer;
A transfer target determining means for determining a file to be transferred;
File transfer means for intermittently transferring a file to be transferred in the communication session;
Throughput measuring means for measuring the throughput of the file transfer;
Backoff time calculating means for calculating the backoff time of intermittent transfer every time the communication session is disconnected,
The back-off time calculating means includes
Means for calculating a provisional value of the back-off time that can promise the transfer deadline based on the untransferred size of the file and the remaining time until the transfer deadline;
Means for randomly setting the back-off time of intermittent transfer between a predetermined lower limit time and the provisional value;
The session control unit disconnects an established session after waiting for a file transfer of one block when the throughput falls below a reference threshold, and reestablishes the communication after the back-off time has elapsed. .   2. The communication terminal device according to claim 1, wherein the file transfer unit continues the file transfer in a block unit if the throughput record is equal to or greater than a predetermined threshold value.   The communication terminal apparatus according to claim 1, wherein the throughput measuring unit measures the throughput every file transfer for one block.   4. The communication terminal apparatus according to claim 1, further comprising transfer target determining means for determining a file to be transferred every time file transfer for one block is completed.   5. The communication terminal apparatus according to claim 4, wherein the transfer target determining unit preferentially determines a file having a shorter remaining time until a transfer deadline as a transfer target.