JP2016136701A - Terminal and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of optimizing a transmission buffer size and a reception buffer size for TCP communication, according to its transmission speed.SOLUTION: A terminal, communicates with a server through a network device, includes: a storage part for storing a transmission buffer size and a reception buffer size, to be used for TCP communication with a server; a reception part for receiving a control signal from a network device; a change part for changing at least either one of the transmission buffer size or the reception buffer size, stored in the storing part, according to the control signal, and for storing the changed size; and a communication part for transmitting/receiving a TCP packet to/from the server, based on the transmission buffer size and the reception buffer size, stored in the storing part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a terminal and a communication method.

  A terminal corresponding to various wireless technologies, such as a smartphone, is known. For example, a terminal equipped with Android (registered trademark) OS (Operating System) includes LTE (Long Term Evolution), wireless LAN (Local Area Network), HSPA (High Speed Packet Access), UMTS (Universal Mobile Telecommunications System), GPRS. It supports wireless access technology called (General packet radio service), EDGE (Enhanced Data GSM Environment), EVDO (Evolution Data Only), and communicates with servers etc. using TCP (Transmission Control Protocol) Is possible.

  When performing the TCP communication, the terminal performs window control according to the setting values of the transmission buffer size and the reception buffer size, thereby making it possible to appropriately control the throughput of the TCP communication. Further, the terminal switches the setting values of the transmission buffer size and the reception buffer size having different sizes for each radio access technology.

JP 2014-192575 A

  Technologies for increasing the communication speed, such as Carrier Aggregation technology (hereinafter referred to as “CA”) and MIMO (Multi Input and Multi Output), have been introduced for LTE wireless technology. By applying these techniques, the peak speed of wireless communication will be significantly increased. For example, when communication is performed with 2 × 2 MIMO with a bandwidth of 20 MHz, the peak speed is 150 Mbps at the maximum. However, when the bandwidth is expanded to 40 MHz by CA, the peak speed of wireless communication is increased to a maximum of 300 Mbps. .

  However, when communication using the LTE technology is performed, the setting values of the transmission buffer size and the reception buffer size of the terminal are fixed. In other words, the transmission buffer size and the reception buffer size cannot be changed to appropriate setting values in response to the increase in the peak speed of wireless communication due to these high-speed technologies. As a result, even if the peak speed of wireless communication increases, the throughput of TCP communication cannot be improved.

  Further, if the setting values of the transmission buffer size and the reception buffer size are simply increased, the CPU resources and memory resources of the terminal are consumed wastefully, and conversely, it may be a factor that decreases the throughput of TCP communication. Therefore, it is necessary to appropriately adjust these buffer sizes according to the communication speed.

  The disclosed technique has been made in view of the above, and provides a technique capable of changing the transmission buffer size and the reception buffer size used for TCP communication to appropriate sizes according to the communication speed. With the goal.

  The terminal of the disclosed technology is a terminal that communicates with a server via a network device, a storage unit that stores a transmission buffer size and a reception buffer size used for TCP communication performed with the server, and a control signal from the network device A change unit that changes at least one of the transmission buffer size and the reception buffer size stored in the storage unit and stores them in the storage unit, based on the control signal, And a communication unit that transmits and receives TCP packets to and from the server based on the transmission buffer size and the reception buffer size stored in the storage unit.

  According to the disclosed technique, it is possible to provide a technique capable of changing the transmission buffer size and the reception buffer size used for TCP communication to appropriate sizes according to the communication speed.

It is a figure which shows the outline | summary of the communication system which concerns on embodiment. It is a figure for demonstrating the calculation method of the optimal receiving window size. It is a figure which shows an example of a function structure of the terminal which concerns on embodiment. It is a figure which shows an example of the hardware constitutions of the terminal which concerns on embodiment. It is a figure which shows an example of a combination table. It is a figure which shows an example of the buffer size setting which concerns on embodiment. It is a figure which shows an example of the process sequence of the process sequence which concerns on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

  In the following description, it is assumed that the terminal according to the embodiment is an Android (registered trademark) OS or a Linux (registered trademark) OS. However, the embodiment is also applied to a terminal including another OS. be able to. Further, although the description will be given on the assumption that the terminal performs wireless communication by LTE, the terminal can also be applied to wireless communication using other wireless technologies.

<Overview>
FIG. 1 is a diagram illustrating an overview of a communication system according to an embodiment. The communication system according to the embodiment includes a terminal 1, a network device 2, and a server 3.

  The terminal 1 has a function of communicating with the network device 2 through wireless communication. In addition, the terminal 1 has a function of performing communication using the TCP with the server 3 via the network device 2. The terminal 1 is, for example, a mobile phone, a smartphone, a tablet, a mobile router, a wearable terminal, or the like. The terminal 1 may be any terminal 1 as long as it is a device having a communication function. The terminal 1 is based on hardware resources such as a CPU such as a processor, a memory device such as a ROM (Read Only Memory), a RAM (Random Access Memory) or a flash memory, an antenna for communicating with the eNB 20, and an RF (Radio Frequency) device. Composed. Each function and process of the terminal 1 may be realized by a processor processing or executing data or a program stored in a memory device. However, the terminal 1 is not limited to the hardware configuration described above, and may have any other appropriate hardware configuration.

  The network device 2 is a mobile communication network provided by a mobile communication provider, and includes a wireless network device and a core network device. In addition, the network device 2 instructs the terminal 1 regarding wireless communication.

  The server 3 is connected to the network device 2. The server 3 has a function of performing communication using the TCP with the terminal 1 via the network device 2.

  Here, the TCP transmission buffer size and the reception buffer size will be described. First, in communication using TCP, TCP packets are efficiently transmitted and received by a mechanism called window control. A device that receives a TCP packet (hereinafter referred to as “reception device”) notifies the device that transmits a TCP packet (hereinafter referred to as “transmission device”) by including the reception window size in an ACK packet.

  The reception window size is a value indicating the amount of TCP packets that can be received by the receiving apparatus at one time. The transmission device controls the number of TCP packets that are continuously transmitted according to the reception window size notified from the reception device. Generally, in order to improve the throughput of TCP communication, it is said that the reception window size needs to be a value corresponding to the communication speed of the network.

  FIG. 2 is a diagram for explaining a method of calculating an optimal reception window size. For example, it is assumed that the communication speed in the section from the server 3 to the network apparatus 2 is 1 Gbps, and the communication speed in the section from the network apparatus 2 to the terminal 1 is 150 Mbps. Also, the RTT (Round Trip) until the TCP packet transmitted from the server 3 (or terminal 1) reaches the terminal 1 (or server 3) and the ACK packet for the reached TCP packet reaches the server 3 (or terminal 1). Time) is assumed to be 120 ms.

The optimum reception window size can be obtained by the following calculation formula.
Receive window size (bytes) = Communication speed ÷ 8 × RTT

  In the example of FIG. 2, among the communication speeds of each section between the terminal 1 and the server 3, the slowest section is 150 Mbps between the terminal 1 and the network device 2. Therefore, the optimal reception window size is 150 Mbps ÷ 8 × 120 ms = 2.25 Mbytes.

  The reception buffer size is the size of a buffer in which the reception device accumulates TCP packets received from the transmission device. In other words, in TCP communication, the OS adjusts the reception window size notified by the reception device to the transmission device within the range of the reception buffer size. That is, in order to improve the throughput of TCP communication, it is necessary to increase the reception buffer size.

  The transmission buffer size is a buffer (transmission buffer) for temporarily storing TCP packets transmitted from the transmission device to the reception device when the transmission device transmits TCP packets to the reception device. The transmission device can transmit TCP packets at a time within a range not exceeding the reception window size notified from the reception device, but can transmit packets larger than the TCP packets stored in the transmission buffer. Can not. That is, unless the transmission buffer size of the transmission device is increased in accordance with the reception window size notified from the reception device, the throughput of TCP communication will not be improved.

  The settings of the reception buffer size and the transmission buffer size differ depending on the OS. For example, in the Android (registered trademark) OS and the Linux (registered trademark) OS, the reception buffer size is a setting file called tcp_rmem and the transmission buffer size is called tcp_wmem (hereinafter, referred to as “tcp_wmem”). Collectively called “configuration file”). In the Android (registered trademark) OS and the Linux (registered trademark) OS, the maximum value, the default value, and the minimum value of the reception buffer size and the transmission buffer size can be set. In accordance with these settings, the OS automatically adjusts the reception buffer size and the transmission buffer size according to the amount of memory available to the OS. The setting file is stored in a memory or a storage device of the terminal and can be referred to as appropriate from a function unit included in the terminal.

  The terminal 1 according to the embodiment accepts the setting related to the wireless layer from the network device 2 and changes the setting file of the OS of the terminal 1 according to the setting related to the wireless layer, so that the terminal 1 and the server 3 It is possible to improve the throughput of TCP communication performed in the network.

<Device configuration>
FIG. 3 is a diagram illustrating an example of a functional configuration of the terminal according to the embodiment. The terminal 1 includes a control signal processing unit 10, a buffer size changing unit 20, and a TCP communication processing unit 30. Each of these means can be realized by, for example, processing that the CPU executes by one or more programs installed in the terminal 1.

  The control signal processing unit 10 receives a setting change instruction regarding the wireless layer from the network device 2 and notifies the buffer size changing unit 20 of the setting contents. For example, the control signal processing unit 10 accepts addition and deletion of Scell (Secondary Cell) in CA and change of MIMO setting from the network device 2. With these settings, the peak speed in wireless communication is changed.

  The buffer size changing unit 20 receives the notification from the control signal processing unit 10 and changes the transmission buffer size and the TCP reception buffer size stored in the setting file to setting values corresponding to the setting of the wireless layer. The buffer size changing unit 20 holds a combination table in advance that associates settings related to the wireless layer and setting values to be set in the setting file, and combines the setting contents related to the wireless layer notified from the control signal processing unit 10. The setting value to be set in the setting file is determined by comparing with the table. Further, the buffer size changing unit 20 notifies the TCP communication processing unit 30 that the setting value of the setting file has been changed. FIG. 5 is a diagram illustrating an example of the combination table. The combination table shown in FIG. 5 includes combinations (settings of theoretical peak speeds in wireless communication corresponding to wireless layer settings (modulation scheme, MIMO configuration, and wireless bandwidth) and setting values to be set in the configuration file. Pattern). For example, when the modulation scheme is 64QAM, the MIMO configuration is 2 × 2 MIMO, and the bandwidth is 20 MHz, it indicates that the setting pattern is Pattern 5. In the case of Pattern 5, the theoretical peak speed of wireless communication is 150 Mbps, and in the case of Pattern 7, the theoretical peak speed of wireless communication is 300 Mbps.

  Since the setting of the wireless layer is generally different for downlink (for network device 2 to terminal 1) communication and uplink (for terminal 1 to network device 2) communication, the theoretical peak speeds thereof are also different. Therefore, the buffer size changing unit 20 determines a corresponding setting pattern for each of the peak speeds of downlink communication and uplink communication.

  When the CA setting is changed, the buffer size changing unit 20 refers to the bandwidth field obtained by summing the bandwidth of the PCell (Primary Cell) and the bandwidth of the Scell (Secondary Cell), thereby setting the configuration file. Determine the setting pattern to be set. For example, when the PCell is 20 MHz and the Scell is 20 MHz, the buffer size changing unit 20 refers to the column whose bandwidth is 40 MHz in the combination table.

  FIG. 6 is a diagram illustrating an example of buffer size setting according to the embodiment. 6A is an example of a setting pattern corresponding to Pattern 5, and FIG. 6B is an example of a setting pattern corresponding to Pattern 7. In the case of FIG. 6A, it is shown that the minimum value, default value, and maximum value of tcp_rmem or tcp_wmem in the setting file should be set to 4096 bytes, 16384 bytes, and 65536 bytes, respectively. Similarly, in the case of FIG. 6B, the minimum value, default value, and maximum value of tcp_rmem or tcp_wmem in the setting file should be set to 8192 bytes, 32768 bytes, and 131072 bytes, respectively.

  Returning to FIG. 3, the description will be continued.

The TCP communication processing unit 30 performs TCP communication with the server 3 based on the setting values of the transmission buffer size and the reception buffer size stored in the OS setting file.
Further, when the TCP communication processing unit 30 receives a notification that the setting file has been changed from the buffer size changing unit 20, the TCP communication processing unit 30 performs communication with the server 3 based on the changed setting value of the reception buffer size. The reception window size of TCP communication is changed. Further, when the TCP communication processing unit 30 receives a notification that the setting file has been changed from the buffer size changing unit 20, the number of TCP packets to be simultaneously transmitted to the server 3 based on the changed setting value of the transmission buffer size. To change.

  FIG. 4 is a diagram illustrating an example of a hardware configuration of the terminal according to the embodiment. As shown in FIG. 4, each device included in the terminal 1 includes, for example, a CPU 101, a RAM 102 and a ROM 103 that are main storage devices, a communication module 104 for performing communication, and an auxiliary storage device 105 such as a hard disk. It is comprised as a computer provided with. And the function of the terminal 1 is exhibited when these components operate | move.

<Processing procedure (1)>
FIG. 7 is a diagram illustrating an example of a processing sequence of a processing procedure according to the embodiment. With reference to FIG. 7, a processing procedure from when the network device 2 is instructed to change the wireless layer setting to the terminal 1 and when the setting file of the terminal 1 is changed will be described. Here, the case where the peak speed of downlink communication is changed by CA will be described. However, the present invention can be similarly applied to a case where the MIMO configuration is changed. Moreover, the setting change of the radio | wireless layer demonstrated below is an example, and the process sequence which concerns on this Embodiment can be applied to various setting changes.

  It is assumed that the TCP communication processing unit 30 of the terminal 1 is performing TCP communication with the server 3 before the process of step S101 is performed. In addition, the radio layer (downlink communication) between the terminal 1 and the network apparatus 2 can apply a 64QAM modulation scheme, the MIMO configuration is 2 × 2 MIMO, the Pcell bandwidth is 20 MHz, and the terminal 1 It is assumed that a setting value corresponding to Pattern 5 in FIG. 5 is set in tcp_rmem of the setting file. The radio layer (uplink communication) between the terminal 1 and the network device 2 has a modulation scheme of 16QAM, a MIMO configuration of 1 × 1 MIMO, and a bandwidth of 10 MHz. It is assumed that a setting value corresponding to Pattern 1 is set.

  In step S101, the network device 2 transmits a setting change instruction signal to the terminal 1, and instructs the terminal 1 to add one SCell having a bandwidth of 20 MHz in downlink communication. This setting change instruction signal is, for example, an RRC Connection Reconfiguration signal. Thereby, the bandwidth of the downlink communication is changed to 40 MHz, and the peak speed of the downlink communication is also changed.

  In step S102, the control signal processing unit 10 of the terminal 1 notifies the buffer size changing unit 20 that the network device 2 has received an instruction to add one 20 MHz Scell in downlink communication. The buffer size changing unit 20 searches the combination table for a setting pattern in which the modulation scheme is 64QAM, the MIMO configuration is 2 × 2 MIMO, and the bandwidth is 40 MHz. In this case, the setting pattern of Pattern 7 is searched. Subsequently, the buffer size changing unit 20 changes the minimum value, default value, and maximum value of tcp_rmem to values corresponding to Pattern 7 in the setting file.

  The TCP communication processing unit 30 performs TCP communication with the server 3 based on the changed setting value of tcp_rmem. The value of tcp_rmem of Pattern 7 is twice the value of tcp_rmem of Pattern 5. Also, the addition of one SCell changes the downlink communication peak speed to double. Therefore, the TCP communication processing unit 30 can double the reception buffer size notified to the server 3, and as a result, the TCP communication throughput from the server 3 to the terminal 1 is increased.

  In step S103, the network device 2 transmits a setting change instruction signal to the terminal 1, and instructs the terminal 1 to delete the SCell added in step S101. This setting change instruction signal is, for example, an RRC Connection Reconfiguration signal. Thereby, the bandwidth of the downlink communication is changed to 40 MHz, and the peak speed of the downlink communication is also changed.

  In step S104, the control signal processing unit 10 of the terminal 1 notifies the buffer size changing unit 20 that the network device 2 has received an instruction to delete a 20 MHz Scell in downlink communication. The buffer size changing unit 20 searches the combination table for a setting pattern in which the modulation scheme is 64QAM, the MIMO configuration is 2 × 2 MIMO, and the bandwidth is 20 MHz. In this case, the setting pattern of Pattern 5 is searched. Subsequently, the buffer size changing unit 20 changes the minimum value, the default value, and the maximum value of tcp_rmem to values corresponding to Pattern 5 in the setting file.

  The TCP communication processing unit 30 performs TCP communication with the server 3 based on the changed setting value of tcp_rmem. By changing the setting value of tcp_rmem to ½, the TCP communication processing unit 30 can perform TCP communication without wasting CPU resources and memory resources of the terminal 1.

<Processing procedure (2)>
Next, the case where the peak speed of uplink communication is changed will be described using FIG. Here, the case where the peak speed of wireless communication is changed by CA will be described. However, the present invention can be similarly applied when the MIMO configuration is changed. Moreover, the setting change of the radio | wireless layer demonstrated below is an example, and the process sequence which concerns on this Embodiment can be applied to various setting changes.

  It is assumed that the TCP communication processing unit 30 of the terminal 1 is performing TCP communication with the server 3 before the process of step S101 is performed. In addition, the radio layer (downlink communication) between the terminal 1 and the network apparatus 2 can apply a 64QAM modulation scheme, the MIMO configuration is 2 × 2 MIMO, the Pcell bandwidth is 20 MHz, and the terminal 1 It is assumed that a setting value corresponding to Pattern 5 in FIG. 5 is set in tcp_rmem of the setting file. The radio layer (uplink communication) between the terminal 1 and the network device 2 has a modulation scheme of 16QAM, a MIMO configuration of 1 × 1 MIMO, and a bandwidth of 10 MHz. It is assumed that a setting value corresponding to Pattern 1 is set. In addition, the setting value of tcp_wmem of Pattern 2 in FIG. 5 is twice the setting value of tcp_wmem of Pattern 1.

  In step S101, the network device 2 transmits a setting change instruction signal to the terminal 1, and instructs the terminal 1 to add one SCell having a bandwidth of 10 MHz in uplink communication. This setting change instruction signal is, for example, an RRC Connection Reconfiguration signal. Thereby, the bandwidth of upstream communication is changed to 20 MHz, and the peak speed of upstream communication is also changed.

  In step S102, the control signal processing unit 10 of the terminal 1 notifies the buffer size changing unit 20 that the network device 2 has received an instruction to add one 10 MHz Scell in downlink communication. The buffer size changing unit 20 searches the combination table for a setting pattern in which the modulation scheme is 16QAM, the MIMO configuration is 1 × 1 MIMO, and the bandwidth is 20 MHz. In this case, the setting pattern of Pattern 2 is searched. Subsequently, the buffer size changing unit 20 changes the minimum value, default value, and maximum value of tcp_wmem to values corresponding to Pattern2 in the setting file.

  The TCP communication processing unit 30 performs TCP communication with the server 3 based on the changed setting value of tcp_wmem. The value of tcp_wmem of Pattern2 is twice the value of tcp_wmem of Pattern1. Also, the addition of one SCell changes the uplink communication peak speed to double. Therefore, the TCP communication processing unit 30 can double the transmission buffer size, and as a result, the throughput of TCP communication from the terminal 1 to the server 3 is increased.

  In step S103, the network device 2 transmits a setting change instruction signal to the terminal 1, and instructs the terminal 1 to delete the SCell added in step S101. This setting change instruction signal is, for example, an RRC Connection Reconfiguration signal. Thereby, the bandwidth of uplink communication is changed to 10 MHz, and the peak speed of uplink communication is also changed.

  In step S104, the control signal processing unit 10 of the terminal 1 notifies the buffer size changing unit 20 that the network device 2 has received an instruction to delete the 10 MHz Scell in uplink communication. The buffer size changing unit 20 searches the combination table for a setting pattern in which the modulation scheme is 16QAM, the MIMO configuration is 1 × 1 MIMO, and the bandwidth is 10 MHz. In this case, the setting pattern of Pattern 1 is searched. Subsequently, the buffer size changing unit 20 changes the minimum value, default value, and maximum value of tcp_wmem to values corresponding to Pattern1 in the setting file.

  The TCP communication processing unit 30 performs TCP communication with the server 3 based on the changed setting value of tcp_wmem. Since the setting value of tcp_wmem is changed to ½, the TCP communication processing unit 30 can perform TCP communication without wasting CPU resources and memory resources of the terminal 1.

<Effect>
As described above, the terminal 1 according to the embodiment increases the transmission buffer size and the reception buffer size set in the OS according to the peak speed of wireless communication. Thereby, the terminal 1 according to the embodiment can improve the throughput of TCP communication according to the wireless peak speed.

  Further, the terminal 1 according to the embodiment reduces the transmission buffer size and the reception buffer size set in the OS in accordance with the peak speed of wireless communication. Thereby, the terminal 1 according to the embodiment can prevent the CPU resource and the memory resource of the terminal 1 from being wasted.

  Further, the terminal 1 according to the embodiment includes a theoretical peak speed in radio communication corresponding to radio layer settings (modulation scheme, MIMO configuration, and radio bandwidth) and a set value to be set in the configuration file. A combination table for defining combinations is held, and the transmission buffer size and reception buffer size set in the OS are changed in accordance with the change of the wireless layer setting instructed by the network device. Thereby, the terminal 1 according to the embodiment can change the transmission buffer size and the reception buffer size to appropriate setting values according to various peak speeds in wireless communication.

<Supplement of embodiment>
As described above, in the embodiment, when the peak speed is different between downlink communication and uplink communication, the buffer size changing unit 20 selects the setting pattern with the higher peak speed, and sets the selected setting pattern to tcp_rmem and tcp_wmem. You may make it do. This is because, for example, depending on the OS, it may be recommended to set tcp_rmem and tcp_wmem to the same value.

  As described above, in the embodiment, the combination table specifies the combination of the theoretical peak speed in the wireless communication corresponding to the setting of the wireless layer and the setting value to be set in the setting file. You may make it prescribe | regulate based on not the theoretical peak speed but the effective peak speed.

  Although the embodiments of the present invention have been described above, the disclosed invention is not limited to the embodiments, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. . Although specific numerical values have been used to facilitate understanding of the invention, these numerical values are merely examples, and any appropriate values may be used unless otherwise specified. The classification of items in the above description is not essential to the present invention, and the items described in two or more items may be used in combination as necessary, or the items described in one item may be used in different items. It may be applied to the matters described in (if not inconsistent). The boundaries between functional units or processing units in the functional configuration diagram do not necessarily correspond to physical component boundaries. The operations of a plurality of functional units may be physically performed by one component, or the operations of one functional unit may be physically performed by a plurality of components.

  As described above, all or part of the embodiments can be implemented by a program. This program can be any random access memory (RAM), flash memory, read only memory (ROM), EPROM, EEPROM, register, hard disk (HDD), removable disk, CD-ROM, database, server 3 or any other suitable storage medium. May be stored.

  As described above, in the embodiment, the control signal processing unit 10 is an example of a receiving unit. The buffer size changing unit 20 is an example of a changing unit. The TCP communication processing unit 30 is an example of a communication unit. The combination table is an example of a setting table.

1 Terminal 2 Network Device 3 Server 10 Control Signal Processing Unit 20 Buffer Size Changing Unit 30 TCP Communication Processing Unit

Claims (4)

A terminal that communicates with a server via a network device,
A storage unit for storing a transmission buffer size and a reception buffer size used for TCP communication performed with the server;
A receiving unit for receiving a control signal from the network device;
Based on the control signal, a change unit that changes at least one of the transmission buffer size and the reception buffer size stored in the storage unit and stores the change in the storage unit;
A communication unit that transmits and receives TCP packets to and from the server based on the transmission buffer size and the reception buffer size stored in the storage unit;
A terminal having The terminal performs wireless communication with the network device,
The changing unit holds a setting table in which radio layer settings are associated with setting values of the transmission buffer size and the reception buffer size, and the radio layer setting included in the control signal is set from the setting table. The transmission buffer size or the reception buffer size corresponding to is searched, and the transmission buffer size or the reception buffer size stored in the storage unit is set to the set value of the searched transmission buffer size or the reception buffer size. The terminal according to claim 1 to be changed. The terminal performs LTE wireless communication with the network device,
The terminal according to claim 1, wherein the control signal is an RRC Connection Reconfiguration signal. A communication method executed by a terminal that communicates with a server via a network device,
Storing a transmission buffer size and a reception buffer size used for TCP communication with the server in a storage unit;
Receiving a control signal from a network device;
Based on the control signal, changing at least one of the transmission buffer size and the reception buffer size stored in the storage unit and storing in the storage unit;
Performing transmission and reception of TCP packets with the server based on the transmission buffer size and the reception buffer size stored in the storage unit;
A communication method comprising:

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