JP2018006944A - Radio communication device, radio communication system, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication device, a radio communication system and a communication method, which reduce a time to the optimization of communication to thereby improve a throughput.SOLUTION: The radio communication device includes: an information acquisition analysis unit which acquires a retransmission rate indicative of a ratio of retransmission to a throughput, on the basis of packet data exchanged between with another radio communication device; a packet size table; a packet size control unit which calculates a packet size on the basis of the throughput and the retransmission rate, so as to store the calculated packet size into the packet size table; and a communication unit. The packet size control unit refers to the packet size table to determine the packet size, outputs the determined packet size to the communication unit. The communication unit performs communication according to the determined packet size.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a wireless communication device, a wireless communication system, and a communication method.

  Currently, a user can receive various services such as a call service and a web browsing service using a smartphone or a tablet terminal.

  In order to enable provision of such a service, for example, retransmission control may be performed between the radio base station apparatus and the terminal apparatus. The retransmission control is, for example, a control method in which a transmission packet is retransmitted from the transmission side or a next transmission packet is transmitted based on a response confirmation message from the reception side. In the wireless section, for example, the transmission packet may not reach the receiving side due to frequency band competition or radio wave interference. For example, such a transmission packet can be relieved by the retransmission control. However, in the retransmission control, there are cases where the transmission delay increases due to repetition of retransmission, or packet loss occurs when the maximum number of retransmissions is reached. In such a case, the throughput decreases.

  On the other hand, in a wired network, congestion control by TCP (Transmission Control Protocol) may be performed. The congestion control is, for example, a control method that combines a slow start and a congestion avoidance algorithm. In the congestion control, for example, when a packet loss or the like occurs, the window size of the transmission packet is reduced, and then the window size is gradually increased. In congestion control, it is possible to avoid congestion due to packet loss or the like, but it may take time until communication is optimized by repeatedly reducing the window size and increasing the window size stepwise.

  Examples of communication technologies include the following. That is, there is a packet communication apparatus that predicts an average random error rate from electric field strength, assumes an error occurrence interval from this error rate, and selects a packet size that provides the highest throughput with respect to the error occurrence interval.

  According to this technique, the throughput can be improved by selecting the packet size in real time.

  In addition, the wireless terminal device or the base station device measures the received electric field strength or error rate (BER (Bit Error Rate)), stores it in the packet, transmits it, and the device that receives the information based on the received information There is a network system in which control information related to packet transmission is changed.

  According to this technique, the apparatus can change the packet size, the value of the retransmission timer, and the window size based on the received information, thereby enabling efficient data communication.

  Further, a requested retransmission rate is stored for each channel, data size information is stored for each channel, and a buffer provided for each channel so as to satisfy a requested retransmission rate for each of a plurality of channels based on the data size information. There is a data receiving apparatus that determines the size of an area.

  According to this technology, it is possible to provide a data receiving apparatus capable of controlling the retransmission rate for each channel of a plurality of LAN (Local Area Network) channels with a limited buffer size.

JP-A-11-205216 JP 11-33234 A JP 2011-142563 A

  However, techniques for predicting an average random error rate and selecting a packet size with the highest throughput or storing an error rate or the like in a packet for transmission are not considered. For this reason, in these techniques, no consideration is given to how to deal with retransmission when retransmission occurs repeatedly, and it may not be possible to prevent a decrease in throughput due to repetition of retransmission. Further, in these techniques, when packet loss occurs due to repeated retransmission, it may take a certain time or more until communication is optimized by performing congestion control.

  Further, no consideration is given to the occurrence of retransmissions with respect to the technique for determining the size of the buffer area provided for each channel so as to satisfy the requested retransmission rate for each of a plurality of channels. Therefore, there is a case where the technique cannot prevent a decrease in throughput due to repeated retransmission. Also, in this technique, when packet loss occurs, it may take a certain time or more until communication is optimized by congestion control.

  Therefore, one disclosure is to provide a wireless communication device, a wireless communication system, and a communication method that reduce the time until communication is optimized and improve the throughput.

  One disclosure includes, in a wireless communication device, an information acquisition analysis unit that acquires a retransmission rate indicating a throughput and a retransmission ratio based on packet data exchanged with another wireless communication device, a packet size table, A packet size control unit that calculates a packet size based on the throughput and the retransmission rate and stores the calculated packet size in the packet size table, and a communication unit, the packet size control unit refers to the packet size table Then, the packet size is determined, and the determined packet size is output to the communication unit, and the communication unit performs communication based on the determined packet size.

  According to one disclosure, it is possible to provide a wireless communication device, a wireless communication system, and a communication method that reduce the time until communication is optimized and improve the throughput.

FIG. 1 is a diagram illustrating a configuration example of a wireless communication system. FIG. 2 is a diagram illustrating a configuration example of a wireless communication system. 3A is a diagram illustrating each configuration example of an AP, and FIG. 3B is a diagram illustrating each configuration example of a terminal device. FIG. 4 is a diagram illustrating a relationship example between the packet size, the retransmission rate, and the throughput. 5A and 5B are examples of radio packets, and FIG. 5C is a diagram illustrating an example of retransmission control. FIG. 6 is a diagram illustrating an example of a packet size table. FIG. 7 is a flowchart showing an operation example including packet size change processing. FIG. 8 is a flowchart showing an example of packet size change processing. 9A is a diagram illustrating each configuration example of the AP, and FIG. 9B is a diagram illustrating each configuration example of the terminal device. FIG. 10A is a flowchart illustrating an operation example when communication is performed with an optimal packet size, and FIG. 10B is a diagram illustrating an example of a packet size table. FIG. 11 is a diagram illustrating an example in which the terminal device moves. 12A is a diagram illustrating each configuration example of an AP, and FIG. 12B is a diagram illustrating each configuration example of a terminal device. FIG. 13 is a flowchart showing an operation example when the terminal device moves. FIG. 14A to FIG. 14C are diagrams illustrating examples of control sections. FIG. 15A illustrates an example of a hardware configuration of an AP, and FIG. 15B illustrates a hardware configuration example of a terminal device.

  Hereinafter, modes for carrying out the present invention will be described. The following examples do not limit the disclosed technology. Each embodiment can be combined as appropriate within a range that does not contradict processing contents.

[First Embodiment]
A first embodiment will be described. FIG. 1 illustrates a configuration example of a wireless communication system 10 according to the first embodiment. The wireless communication system 10 includes a wireless communication device 100 and another wireless communication device 200. For example, the wireless communication device 100 may be an access point or a wireless base station device, and the other wireless communication device 200 may be a terminal device. Alternatively, for example, the wireless communication device 100 may be a terminal device, and the other wireless communication device 200 may be an access point or a wireless base station device.

  The wireless communication apparatus 100 includes an information acquisition / analysis unit 120, a packet size control unit 160, a packet size table 130, and a communication unit 115.

  The information acquisition / analysis unit 120 acquires a retransmission rate indicating a throughput and a retransmission ratio based on packet data exchanged with another wireless communication apparatus 200.

  The packet size control unit 160 calculates the packet size based on the throughput and the retransmission rate, and stores the calculated packet in the packet size table 130. The packet size table 130 stores the packet size.

  Further, the packet size control unit 160 determines the packet size with reference to the packet size table 130, and outputs the determined packet size to the communication unit 115.

  The communication unit 115 performs communication based on the determined packet size.

  Thus, in the first embodiment, for example, the packet size control unit 160 calculates the packet size based on the throughput and the retransmission rate, and stores the calculated packet size in the packet size table 130.

  FIG. 4 shows an example of the relationship between the packet size, the throughput, and the retransmission rate. Details of FIG. 4 will be described in the second embodiment, but the throughput may be improved by determining the packet size based on the throughput and the retransmission rate. For example, when the throughput is equal to or lower than the first threshold and the retransmission rate is equal to or higher than the second threshold, it is possible to improve the throughput by making the packet size smaller than the size used so far. Also, for example, when the throughput is equal to or less than the first threshold and the retransmission rate is smaller than the second threshold, the packet size is set larger than the size used so far, so that the wireless section with another wireless communication device It is possible to improve throughput.

  Therefore, the packet size table 130 stores the packet size calculated based on the throughput and the retransmission rate, and the throughput can be improved over the packet size used so far.

  In the first embodiment, for example, the packet size control unit 160 determines the packet size by referring to the packet size table 130, and actually exchanges packets with a certain packet size to measure the throughput. It is possible to achieve higher speed than the case. In this case, the packet size stored in the packet size table 130 is, for example, a packet size that improves throughput in the wireless section. For this reason, for example, even if the wireless communication device exchanges packets of the packet size in a wired section connected to another communication device, transmission waiting or the like does not occur. Therefore, even if congestion control is performed in the wired section, for example, packet loss or the like does not occur, and window size reduction or the like caused by congestion control does not occur. Therefore, the wireless communication apparatus 100 can also speed up the time until the communication is optimized, for example, as compared with the case where the window size is reduced by congestion control.

[Second Embodiment]
<Configuration example of wireless communication system>
Next, a second embodiment will be described. FIG. 2 is a diagram illustrating a configuration example of the wireless communication system 10 according to the second embodiment.

  The wireless communication system 10 includes an access point (hereinafter also referred to as “AP” (Access Point)) 100 and terminal devices (hereinafter also referred to as “terminals”) 200-1 and 200-2. The wireless communication system 10 is connected to the network 300.

  The AP 100 is, for example, a wireless communication device that performs wireless communication with the terminals 200-1 and 200-2 located within the service provisionable range. For example, the AP 100 can provide various services such as a call service and a Web browsing service to the terminals 200-1 and 200-2.

  The terminals 200-1 and 200-2 are wireless communication devices that perform wireless communication with the AP 100, such as feature phones, smartphones, tablet terminals, personal computers, and game devices. The terminals 200-1 and 200-2 can receive the above-described service via the AP 100, for example.

  In the second embodiment, the AP 100 and the terminals 200-1 and 200-2 perform wireless communication by a wireless LAN (Local Area Network) system, for example. As the wireless LAN system, for example, a wireless communication system specified by IEEE, such as IEEE (The Institute of Electrical and Electronics Engineers) 802.11 series or IEEE 802.15 series, is used. In some cases, WiFi and wireless LAN are not distinguished. In the wireless LAN system, for example, wireless communication is performed using carrier sense.

  However, in the second embodiment, for example, a radio base station apparatus may be used instead of the AP 100. In the wireless base station apparatus, for example, a wireless communication method specified by 3GPP (Third Generation Partnership Project) such as LTE (Long Term Evolution) -Advanced method or 5G (5th Generation Mobile Networks or 5the Generation Wireless System) method is used. It is done. For example, the radio base station apparatus performs scheduling of radio resources and performs radio communication with the terminals 200-1 and 200-2 according to the scheduling result.

  In the example of FIG. 2, an example of two terminals 200-1 and 200-2 is shown, but one or three or more may be used. Hereinafter, unless otherwise specified, the terminals 200-1 and 200-2 may be referred to as the terminal 200.

  Next, configuration examples of the AP 100 and the terminal 200 will be described.

<Configuration example of AP>
FIG. 3A is a diagram illustrating a configuration example of the AP 100. The AP 100 includes a wireless communication unit 110, an information acquisition / analysis unit (hereinafter also referred to as an “information acquisition analysis unit”) 120, a packet size table 130, a throughput determination unit 140, a retransmission rate determination unit 150, and a packet size control unit. 160 and a wired communication unit 170.

  The wireless communication unit 110 performs wireless communication with the terminal 200. For example, the wireless communication unit 110 generates a wireless packet (or packet data) having a packet size instructed by the packet size control unit 160, converts the wireless packet into a wireless signal, and transmits the converted wireless signal to the terminal 200. Send. In addition, for example, the wireless communication unit 110 receives a wireless signal transmitted from the terminal 200, extracts a wireless packet from the received wireless signal, extracts various information from the extracted wireless packet, and extracts the extracted information as information. The data is output to the acquisition analysis unit 120. The wireless packet may be, for example, an L1 (Layer 1) packet.

  The information acquisition / analysis unit 120 receives information, data, and the like from the wireless communication unit 110, and acquires the radio field intensity and noise intensity measured by the terminal 200 from the received information. The information acquisition / analysis unit 120 outputs the acquired radio wave intensity and noise intensity to the packet size control unit 160.

  The information acquisition / analysis unit 120 also acquires the packet size from the wireless communication unit 110. The information acquisition / analysis unit 120 outputs the acquired packet size to the packet size control unit 160.

  Furthermore, the information acquisition / analysis unit 120 can measure the throughput between the AP 100 and the terminal 200 or measure the retransmission rate based on, for example, a wireless packet transmitted from the wireless communication unit 110. is there. The throughput can be calculated based on, for example, the number of wireless packets transmitted by the information acquisition analysis unit 120 within a unit time. The retransmission rate represents, for example, the rate of retransmission of wireless packets, and is based on the number of wireless packets received a NACK (Negative ACK) signal for the wireless packets transmitted from the wireless communication unit 110. The information acquisition / analysis unit 120 may calculate the information. Alternatively, the information acquisition / analysis unit 120 calculates a retransmission rate based on the number of radio packets that have not returned an ACK (Acknowledgement) signal within a predetermined time for a radio packet transmitted from the radio communication unit 110. May be. The information acquisition / analysis unit 120 outputs the measured throughput to the throughput determination unit 140 and the measured retransmission rate to the retransmission rate determination unit 150.

  Furthermore, the information acquisition / analysis unit 120 calculates the packet size based on, for example, the correlation between the radio wave intensity, the noise intensity, and the packet size, and stores the calculated packet size in the packet size table 130. The information acquisition analysis unit 120 may calculate the packet size from the radio wave intensity and the noise intensity according to a certain calculation formula. The packet size stored by the information acquisition / analysis unit 120 may be, for example, an initial packet size.

  The packet size table 130 is, for example, a table that stores a packet size that maximizes the throughput. For example, in the packet size table 130, the initial packet size is stored by the information acquisition analysis unit 120, and the changed packet size is stored by the packet size control unit 160. FIG. 5 shows an example of the packet size table 130. Details of the packet size and the packet size table 130 will be described later.

  Returning to FIG. 3A, the throughput determination unit 140 receives the throughput output from the information acquisition analysis unit 120, and determines whether or not the received throughput is equal to or greater than the first threshold. Throughput determination unit 140 outputs the determination result to packet size control unit 160.

  The retransmission rate determination unit 150 receives the retransmission rate output from the information acquisition analysis unit 120 and determines whether the received retransmission rate is equal to or higher than a second threshold. The retransmission rate determination unit 150 outputs the determination result to the packet size control unit 160.

  The packet size control unit 160 changes the packet size based on the determination results output from the throughput determination unit 140 and the retransmission rate determination unit 150, for example. That is, the packet size control unit 160 changes (or adjusts) the packet size based on, for example, the throughput and the retransmission rate. How the packet size control unit 160 changes the packet size will be described in an operation example. For example, the packet size control unit 160 reads out the packet size corresponding to the radio wave intensity and the noise intensity received from the information acquisition analysis unit 120 from the packet size table 130, thereby determining which packet size is used for communication. . The packet size control unit 160 outputs the determined packet size to the wireless communication unit 110. Further, the packet size control unit 160 outputs the determined packet size to the wired communication unit 170.

  A wired communication unit 170 performs wired communication with a server device connected to the network 300. For example, the wired communication unit 170 exchanges a TCP packet having the packet size received from the packet size control unit 160 in the window size with the server device or the like. Alternatively, the wired communication unit 170 transmits the packet size as the window size of the TCP packet to the server device or the like. The server apparatus and the terminal 200 may exchange TCP packets with the notified window size.

<Example of terminal configuration>
FIG. 3B is a diagram illustrating a configuration example of the terminal 200. The terminal 200 includes a wireless communication unit 210, an information acquisition analysis unit 220, a packet size table 230, a throughput determination unit 240, a retransmission rate determination unit 250, and a packet size control unit 260. Note that the configuration example of the terminal 200 illustrated in FIG. 3B represents an example in which the terminal 200 includes the packet size table 230 and performs communication based on the packet size.

  The wireless communication unit 210 performs wireless communication with the AP 100. For example, the wireless communication unit 210 generates a TCP packet having the packet size specified by the packet size control unit 260 as a window size, generates a wireless packet based on the generated TCP packet, and generates the generated wireless packet as a wireless signal. And the converted radio signal is transmitted to the AP 100. Further, the wireless communication unit 210 receives, for example, a wireless signal transmitted from the AP 100, extracts a wireless packet from the received wireless signal, extracts a TCP packet from the extracted wireless packet, and extracts various information from the TCP packet. The extracted information is output to the information acquisition / analysis unit 220.

  For example, the information acquisition / analysis unit 220 acquires radio wave intensity and noise intensity from the information received from the wireless communication unit 210, and outputs the acquired radio wave intensity and noise intensity to the packet size control unit 260. For example, the radio communication unit 210 may measure the radio wave intensity and the noise intensity based on the radio signal received from the AP 100, and the information acquisition / analysis unit 220 may acquire the radio wave intensity and the noise intensity by acquiring the measurement result.

  The information acquisition / analysis unit 220 extracts, for example, the throughput and retransmission rate information measured by the AP 100 from the information received from the wireless communication unit 210. The throughput determination unit 240 extracts the extracted throughput from the extracted retransmission rate. Output to retransmission rate determination section 250. For example, the throughput and the retransmission rate are measured by the AP 100 and transmitted to the terminal 200.

  Furthermore, the information acquisition / analysis unit 220 calculates the packet size based on, for example, the correlation between the radio wave intensity, the noise intensity, and the packet size, and stores the calculated packet size in the packet size table 230. The information acquisition analysis unit 220 may calculate the packet size from the radio wave intensity and the noise intensity according to a certain calculation formula. The packet size calculated in this way may be, for example, an initial packet size.

  The packet size table 230 is a table storing, for example, a packet size that maximizes the throughput. The packet size in this case is, for example, the window size of the TCP packet. The packet size table 230 also stores the changed packet size by the packet size control unit 260.

  The throughput determination unit 240 receives the throughput output from the information acquisition analysis unit 220 and determines whether the received throughput is equal to or greater than a first threshold. Throughput determination unit 240 outputs the determination result to packet size control unit 260.

  The retransmission rate determination unit 250 receives the retransmission rate output from the information acquisition analysis unit 220 and determines whether or not the received retransmission rate is equal to or higher than a second threshold. Retransmission rate determination section 250 outputs the determination result to packet size control section 260.

  The packet size control unit 260 changes the packet size based on the determination results output from the throughput determination unit 240 and the retransmission rate determination unit 250, for example. That is, the packet size control unit 260 changes the packet size based on, for example, the throughput and the retransmission rate. For example, the packet size control unit 260 stores the changed packet size in the packet size table 230. Further, the packet size control unit 260 reads out the packet size corresponding to the radio wave intensity and the noise intensity received from the information acquisition analysis unit 220 from the packet size table 230, for example, which packet size is used for communication. decide. The packet size control unit 260 outputs the determined packet size to the wireless communication unit 210.

<Relationship between packet size, throughput, and retransmission rate>
As described above, the packet size control unit 160 of the AP 100 changes the packet size based on the throughput and the retransmission rate, for example. Here, the relationship between the packet size, the throughput, and the retransmission rate will be described.

  FIG. 4 is a graph showing an example of the relationship between packet size, retransmission rate, throughput, and overhead. In FIG. 4, the horizontal axis represents the packet size, and the vertical axis represents the retransmission rate or throughput. FIG. 4 shows an example of the relationship between the packet size, the retransmission rate, the throughput, and the overhead in the wireless section, but can also be applied in the wired section. However, the following description will be made assuming a wireless section.

  The smaller the packet size, the larger the overhead, and the larger the overhead, the smaller the throughput. That is, when the packet size is smaller than the third threshold value, the number of transmitted packets is increased and the overhead is larger than the fourth threshold value as compared with the case where the packet size is not changed.

  FIG. 5A and FIG. 5B show an example when a wireless packet is divided. As shown in FIG. 5A and FIG. 5B, for example, when a 1500-byte wireless packet is divided into three, each divided packet includes a 60-byte header. Compared to the wireless packet, the number of transmission bytes including the header increases, and the overhead becomes larger than the fourth threshold value. Due to this increase in overhead, when 1500 bytes of data are transmitted, the time after division takes more time than before division, so the throughput after division is reduced. That is, when the overhead is larger than the fourth threshold, the throughput is lower than the first threshold.

  Also in the example shown in FIG. 5C, the time to wait for ACK or NACK after packet # 1 is transmitted is longer than that before the division due to the division of the wireless packet. Therefore, also in the example of FIG. 5C, when the overhead is larger than the fourth threshold, the throughput is lower than the first threshold.

  Returning to FIG. 4, as shown on the left side of FIG. 4, when the packet size is smaller than the third threshold, the overhead becomes larger than the fourth threshold, and the throughput becomes lower than the first threshold.

  Further, as shown in FIG. 5A, for example, consider a case where a bit error occurs in the transmission bits before division, and retransmission occurs due to this bit error. In this case, there is one retransmission packet for one wireless packet, and the retransmission rate is 1/1. On the other hand, after the division, for example, when a retransmission occurs in the second wireless packet including the transmission bits before the division, the retransmission rate in this case is 1/3. Therefore, when radio packets are combined into one, the overhead is reduced and the retransmission rate is increased. In this case, in the example shown in FIG. 5A and FIG. 5B, 1500 bytes included in one wireless packet may not be transmitted before retransmission by retransmission, but at least 1000 after division is not possible. Byte data transmission is possible. Therefore, when wireless packets are combined into one, the retransmission rate may increase and the throughput may decrease.

  Returning to FIG. 4, as shown on the right side of FIG. 4, when the packet size is equal to or larger than the third threshold, the overhead is equal to or smaller than the fourth threshold, the retransmission rate is equal to or larger than the second threshold, and the throughput is first. Lower than the threshold value.

  Therefore, for example, as shown on the right side of FIG. 4, when the throughput is equal to or lower than the first threshold and the retransmission rate is equal to or higher than the second threshold, the packet size is made smaller than that used so far. Thereby, the throughput can be improved. On the other hand, for example, as shown on the left side of FIG. 4, when the throughput is equal to or smaller than the first threshold and the retransmission rate is smaller than the second threshold, the packet size is set larger than that used so far. Thereby, the throughput can be improved.

  As described above, the packet size control unit 160 according to the second embodiment can improve the throughput by changing the packet size based on the retransmission rate and the throughput.

<Example of packet size table>
FIG. 6 is a diagram illustrating an example of the packet size table 130. The numerical value stored in the packet size table 130 represents the packet size. As described above, the initial packet size is stored in the table 130 based on the correlation between the radio wave intensity and the noise intensity, and the packet size is changed based on the retransmission rate and the throughput. Thereafter, based on the changed packet size table 130, the packet size is selected according to the radio wave intensity and the noise intensity, and the packet size is determined. Thereafter, the packet size is changed during communication, and the changed packet size is stored in the packet size table 130.

  In the example of FIG. 6, three items of “high”, “medium”, and “small” are stored for both radio field intensity and noise intensity, but two items (for example, “large” and “small”) are stored. May be stored, or four or more items may be stored. In any case, it is possible to store two or more items in the packet size table 130 by classifying the radio wave intensity and noise intensity based on one or more threshold values.

<Operation example>
Next, an operation example will be described. Regarding the operation example, the following three cases will be described in order.
(1) Example of operation when packet size is undefined (2) Example of operation when packet size is defined and communication is performed with optimal packet size (3) Example of operation when terminal is moving (1) is performed first, and then (2) or (3) is performed.

<1. Example of operation when packet size is undefined>
FIG. 7 and FIG. 8 are flowcharts showing an operation example of storing the packet size in the packet size table 130 when the packet size is undefined. 7 and 8 show an example of operations performed in the AP 100, for example.

  When the AP 100 starts processing (S10), it acquires the current radio wave intensity and noise intensity (S11). For example, the information acquisition / analysis unit 120 acquires the radio wave intensity and noise intensity measured at the terminal 200 and transmitted from the terminal 200 from information output from the wireless communication unit 110.

  Next, the AP 100 determines the packet size (S12). For example, the information acquisition / analysis unit 120 determines an initial packet size based on the acquired radio wave intensity and noise intensity, and stores the determined initial packet size in the packet size table 130.

  Next, the AP 100 determines whether communication is in progress (S13). For example, when the information acquisition / analysis unit 120 acquires information from the wireless communication unit 110, it may be determined that communication is being performed, and when information cannot be acquired within a certain time, it may be determined that communication is not being performed.

  When the AP 100 determines that communication is in progress (YES in S13), it determines whether the throughput is equal to or less than a threshold value (S14). For example, the throughput acquired by the information acquisition analysis unit 120 is output to the throughput determination unit 140, and the throughput determination unit 140 determines whether the received throughput is equal to or less than a first threshold value.

  When the throughput is equal to or less than the threshold (YES in S14), the AP 100 performs a packet size changing process (S15). For example, when the throughput determination unit 140 outputs the determination result to the packet size control unit 160, and the packet size control unit 160 obtains the determination result of the throughput equal to or less than the first threshold value from the throughput determination unit 140, the packet size change process I do. Note that the throughput determination unit 140 stores, for example, the throughput used for the determination in an internal memory or the like.

  FIG. 8 is a flowchart showing an example of packet size change processing. When starting the packet size changing process, the AP 100 determines whether or not the retransmission rate is equal to or greater than a threshold (S150). For example, the information acquisition analysis unit 120 outputs the acquired retransmission rate to the retransmission rate determination unit 150, and the retransmission rate determination unit 150 determines whether or not the received retransmission rate is equal to or higher than the second threshold.

  When the retransmission rate is equal to or higher than the threshold (YES in S150), the AP 100 decreases the packet size stored in the packet size table 130 (S151). In this case, since the throughput is equal to or lower than the first threshold (YES in S14 in FIG. 7) and the retransmission rate is equal to or higher than the second threshold (YES in S150), as described in FIG. By making the packet size smaller than the conventional packet size, the throughput can be improved. For example, the packet size control unit 160 performs the following processing. That is, when the packet size control unit 160 obtains a determination result that the retransmission rate is equal to or higher than the second threshold value from the retransmission rate determination unit 150, the packet size control unit 160 sets the packet size corresponding to the radio wave intensity and noise intensity received from the information acquisition analysis unit 120. Read from the packet size table 130. Then, the packet size control unit 160 changes the packet size to be smaller than the read packet size by a predetermined size.

  Next, the AP 100 outputs the changed packet size to the wireless communication unit 110 and the wired communication unit 170 (S152). For example, the packet size control unit 160 outputs the changed packet size to the wireless communication unit 110 and the wired communication unit 170.

  Next, the AP 100 determines whether or not the throughput is improved (S153). Here, the AP 100 performs wireless communication with the changed packet size, and determines whether the throughput is improved with the packet size. For example, the AP 100 performs the following processing. That is, the wireless communication unit 110 performs wireless communication using a wireless packet having a packet size received from the packet size control unit 160, and the information acquisition analysis unit 120 measures the number of wireless packets transmitted per unit time in the wireless communication unit 110. To measure the throughput. The information acquisition / analysis unit 120 outputs the measured throughput to the throughput determination unit 140, and the throughput determination unit 140 determines whether or not the received throughput is higher than the throughput before the packet size is reduced (S151). Determine.

  For example, the throughput determination unit 140 retains the latest throughput used for the determination in S153 by overwriting and storing the throughput received from the information acquisition analysis unit 120 in an internal memory or the like. Thereafter, when the iterative process is performed, the throughput determination unit 140 determines whether the throughput has been improved by comparing the throughput stored in the internal memory with the throughput received from the information acquisition analysis unit 120. It becomes possible.

  If the AP 100 determines that the throughput has improved (YES in S153), the process proceeds to S151 and the above-described processing is repeated. On the other hand, when the AP 100 determines that the throughput is not improved (NO in S153), the AP 100 returns the packet size to the previous packet size (S154). The previous packet size becomes the changed packet size.

  In the processing from S151 to S154, for example, the AP 100 performs the following processing. That is, the AP 100 gradually decreases the packet size until the throughput is not improved (YES loop in S153). When the throughput does not improve (NO in S153), the AP 100 sets the last packet size with improved throughput as the changed packet size. For example, the packet size control unit 160 stores the changed packet size in an internal memory or the like, and reads out the packet size from the internal memory as appropriate, so that the previous packet size (or the last packet size with improved throughput) is obtained. ) Can be obtained.

  On the other hand, when the retransmission rate is not greater than or equal to the threshold (NO in S150), the AP 100 increases the packet size (S155). In this case, the throughput is equal to or lower than the first threshold (YES in S14 of FIG. 7), and the retransmission rate is smaller than the second threshold (NO in S150). As described with reference to FIG. 4, it is possible to improve the throughput by increasing the packet size so far. For example, the packet size control unit 160 reads the packet size corresponding to the radio wave intensity and noise intensity received from the information acquisition analysis unit 120 from the packet size table 130, and sets the packet size to be larger than the read packet size by a predetermined size. change.

  Next, the AP 100 outputs the changed packet size to the wireless communication unit 110 and the wired communication unit 170 (S156).

  Next, the AP 100 determines whether or not the throughput has improved with the changed packet size (S157). Then, the AP 100 gradually increases the packet size until the throughput is not improved (YES loop in S157). When the throughput does not improve (NO in S157), the AP 100 returns the packet size to the previous packet size (or the last packet size with improved throughput) (S154). The previous packet size becomes the changed packet size.

  Returning to FIG. 7, when the AP 100 finishes the packet size changing process (S15), the radio wave intensity, the noise intensity, and the changed packet size are reflected in the packet size table 130 (S16). For example, the packet size control unit 160 overwrites and stores the packet size stored in the packet size table 130 corresponding to the radio wave intensity and noise intensity acquired from the information acquisition analysis unit 120 with the changed packet size.

  And a process transfers to S13 and AP100 repeats the process mentioned above.

  On the other hand, if the AP 100 is not communicating (NO in S13), the series of processing ends (S17).

  By the above processing, for example, the packet size table 130 shown in FIG. 6 is created.

  As described above, in the second embodiment, the packet size table 130 reflects the packet size with the maximum throughput during communication. Therefore, the packet size table 130 stores the latest packet size that maximizes the throughput.

  Note that the flowcharts shown in FIGS. 7 and 8 can also be executed in the terminal 200, for example. In this case, for example, the acquisition of the radio wave intensity and the noise intensity (S11) is acquired by the information acquisition analysis unit 220 based on a wireless packet transmitted from the AP 100 or the like. Further, the throughput and retransmission rate acquired by the AP 100 are transmitted to the terminal 200 and can be acquired by the information acquisition analysis unit 220. Further, the throughput determination (S14) is determined by the throughput determination unit 240, and the retransmission rate determination (S150) is determined by the retransmission rate determination unit 250. Further, packet size change (S151 to S157) and reflection (S16) are performed by the packet size control unit 260. However, the packet size is, for example, the window size for the TCP packet. When the packet size is changed at the terminal 200, for example, the window size of a TCP packet exchanged between the terminal 200 and a server connected to the network 300 is set as the change target. The window size of the TCP packet may be, for example, the packet size of the TCP packet.

<2. Example of operation when packet size is defined and communication is performed with optimal packet size>
Next, an operation example when wireless communication and wired communication are performed using the packet size stored in the packet size table 130 will be described.

  9A shows a configuration example of the AP 100 in this operation example, and FIG. 9B shows a configuration example of the terminal 200 in this operation example. For example, the AP 100 may have the configuration example shown in FIG. 3A, and the terminal 200 may have the configuration example shown in FIG.

  FIG. 10A is a flowchart showing this operation example, and FIG. 10B shows an example of the packet size table 130.

  When the AP 100 starts processing (S20), it acquires the current radio wave intensity and noise intensity (S21).

  Next, the AP 100 refers to the packet size table 130 and determines the packet size (S22). For example, the packet size control unit 160 reads the packet size corresponding to the radio wave intensity and noise intensity received from the information acquisition analysis unit 120 with reference to the packet size table 130. In the example of FIG. 10B, the packet size table 130 includes items of “high”, “medium”, and “small” for the radio wave intensity. In this case, for example, the packet size control unit 160 compares the received radio wave intensity with the first radio wave intensity threshold value and the second radio wave intensity threshold value so that the received radio wave intensity is “high”, “medium”, “ It may be determined whether or not “small” is met. The same applies to the noise intensity. In the example of FIG. 10B, the packet size control unit 160 represents an example in which “1250” is determined as the packet size from the packet size table 130.

  Next, the AP 100 outputs the determined packet size to the wireless communication unit 110 and the wired communication unit 170 (S23). The wireless communication unit 110 performs wireless communication with the terminal 200 using the received wireless packet having the packet size. Further, the wired communication unit 170 communicates with the network 300 (or a server connected to the network 300) using the received packet size as the window size of the TCP packet.

  FIG. 14A and FIG. 14B are diagrams illustrating examples of control target sections. As shown in FIG. 14A, since the AP 100 performs wireless communication with the terminal 200 using wireless packets having the determined packet size, wireless communication can be performed with the maximum throughput in the wireless section. Further, as shown in FIG. 14B, the AP 100 communicates with the network 300 using a window-size TCP packet having the same size as the determined packet size. In this case, for example, since the throughput of the wireless section is maximized, the AP 100 does not wait for transmission even when a TCP packet of such a size is received from the network 300. Accordingly, congestion does not occur in the AP 100, and the window size of the TCP packet is not reduced even if congestion control is performed. Therefore, optimal communication is possible even in a wired section.

  Returning to FIG. 10A, when the AP 100 outputs the packet size to each of the communication units 110 and 170 (S23), the series of processing ends (S24).

  Note that the flowchart shown in FIG. 10A can also be executed in the terminal 200. The packet size table 230 (for example, FIG. 9B) of the terminal 200 stores an optimal packet size that maximizes the throughput in the wireless section. Therefore, the terminal 200 performs communication using a TCP packet having the same window size as that of the packet size, so that the throughput is maximized in the wireless section and optimum communication without congestion occurring in the wired section is possible. FIG. 14C illustrates an example in which the window size of the TCP packet is controlled between the terminal 200 and the network 300 so that optimal communication is performed in both the wireless section and the wired section.

  As described above, in the second embodiment, for example, the AP 100 performs communication using the packet size stored in the packet size table 130. Therefore, the AP 100 only needs to read the packet size from the packet size table 130, and can obtain the optimum packet size at a higher speed than when the packet is actually transmitted with the packet size. Become. In this case, the packet size has the maximum throughput in the wireless section, and the throughput can be improved. Further, in this case, the AP 100 or the terminal 200 performs communication using the TCP packet having the packet size, so that the throughput is maximum in the wireless section, and congestion does not occur in the wired section, and optimal communication can be performed as a whole. It becomes possible. Therefore, the AP 100 and the terminal 200 perform communication using the packet size stored in the packet size table 130 until the communication is optimized as compared with the case where the packet is actually transmitted with the packet size. Time can be increased.

<3. Example of operation when the terminal is moving>
Next, an operation example when the terminal 200 is moving will be described. When the terminal 200 is moving, the radio wave intensity and the noise intensity change. Therefore, the AP 100 and the terminal 200 may acquire the packet size corresponding to the change and perform communication.

  FIG. 11 shows an example when the terminal 200 is moving. In the example of FIG. 11, at the point X, the terminal 200 has a radio wave intensity for the AP 100-1 larger than the first radio wave intensity threshold (“large”), and a noise intensity for the AP 100-2 is equal to or smaller than the second noise intensity threshold (“small ]). Thereafter, the terminal 200 moves from the point X to the point Y. At the point Y, the terminal 200 has a radio wave intensity equal to or lower than the second radio wave intensity threshold (“small”) and a noise intensity equal to or lower than the first noise intensity threshold and larger than the second noise intensity threshold (“medium”).

  12A shows a configuration example of the AP 100, and FIG. 12B shows a configuration example of the terminal 200. The AP 100 further includes a radio wave / noise state determination unit 180. The terminal 200 further includes a radio wave / noise state determination unit 280.

  For example, the radio wave / noise state determination units 180 and 280 acquire the radio wave intensity and the noise intensity from the information acquisition analysis units 120 and 220, respectively, and determine whether there is a difference between the radio wave intensity and the noise intensity acquired last time. The determination result is output to the packet size control units 160 and 260.

  The radio wave / noise status determination units 180 and 280 include, for example, an internal memory, read out the radio wave intensity and noise intensity acquired last time from the internal memory, and respectively acquire the radio wave intensity and noise intensity acquired from the information acquisition analysis units 120 and 220. Compare. The radio wave / noise situation determination units 180 and 280 store the latest radio wave intensity and noise intensity by overwriting and storing the radio wave intensity and noise intensity acquired from the information acquisition analysis units 120 and 220 in the internal memory after the comparison. Is done. Thereafter, when the radio wave / noise status determination units 180 and 280 acquire the radio wave intensity and the noise intensity from the information acquisition analysis unit 120, they are read from the internal memory as the previous radio wave intensity and noise intensity.

  FIG. 13 is a flowchart of this operation example. When the AP 100 starts processing (S30), it determines whether communication is in progress (S31). If the AP 100 is communicating (YES in S31), the AP 100 acquires the current radio wave intensity and noise intensity (S32), and determines whether or not they are different from the previous values (S33).

  When the acquired radio wave intensity and noise intensity are different from the previously acquired radio wave intensity and noise intensity (YES in S33), the AP 100 determines the packet size with reference to the packet size table 130 (S34). For example, when the terminal 200 moves from the point X to the point Y (for example, FIG. 11), the radio wave intensity is “high”, the noise intensity is “low”, the radio wave intensity is “low”, and the noise intensity is “medium”. Is different. In this case, for example, the packet size control unit 160 refers to the packet size table 130 and acquires the packet size “750” having the radio wave intensity “low” and the noise intensity “medium”. The packet size control unit 160 determines “750” as the packet size, and notifies the wireless communication unit 110 and the wired communication unit 170 (S35). Thereafter, the AP 100 communicates with the terminal 200 and the network 300 with the changed packet size. The difference may be determined as YES in S33 when either the radio wave intensity or the noise intensity is different, or may be determined as YES in S33 when both the radio wave intensity and the noise intensity are different. Good.

  On the other hand, when the AP 100 is not communicating (NO in S31), the series of processing ends (S36).

  Note that the flowchart shown in FIG. 13 can also be executed in the terminal 200, for example. The packet size in this case is, for example, the window size of the TCP packet (S34).

  Thus, even when the terminal 200 moves, the AP 100 and the terminal 200 can acquire the packet size according to the radio wave intensity and noise intensity of the moved destination from the packet size tables 130 and 230. Therefore, the AP 100 and the terminal 200 can speed up the time until the communication is optimized as compared with the case where the packet size is determined after the actual communication with the packet size. Further, since the throughput is maximum in the wireless section, it is possible to improve the throughput.

[Other embodiments]
15A illustrates a hardware configuration example of the AP 100, and FIG. 15B illustrates a hardware configuration example of the terminal 200.

  The AP 100 includes a CPU (Central Processing Unit) 190, a RAM (Random Access Memory) 191, a ROM (Read Only Memory) 192, a DISK 193, an antenna 194, a wireless unit 195, and an IF (Interface) 196. The wireless unit 195 and the IF 196 may be included in a NIC (Network Interface Card).

  For example, the CPU 190 reads out a program stored in the ROM 192, loads the program into the RAM 191, and executes the loaded program, whereby the information acquisition / analysis unit 120, the throughput determination unit 140, the retransmission rate described in the second embodiment are executed. The function of the determination unit 150 can be executed. Further, the CPU 190 can execute the functions of the packet size control unit 160 and the radio wave / noise status determination unit 180 by executing the program, for example. The CPU 190 corresponds to, for example, the information acquisition analysis unit 120, the throughput determination unit 140, the retransmission rate determination unit 150, the packet size control unit 160, and the radio wave / noise status determination unit 180.

  Also, the RAM 191 stores, for example, the packet size table 130 in the second embodiment. The RAM 191 corresponds to the packet size table 130, for example. Furthermore, the antenna 194 and the wireless unit 195 correspond to, for example, the wireless communication unit 110 in the second embodiment. Further, the IF 196 corresponds to, for example, the wired communication unit 170 in the second embodiment.

  The terminal 200 includes a CPU 290, a RAM 291, a ROM 292, a DISK 293, an antenna 294, and a wireless unit 295. Note that the wireless unit 295 may be included in the NIC 297, for example.

  For example, the CPU 290 reads out a program stored in the ROM 292, loads the program into the RAM 291 and executes the loaded program, whereby the information acquisition analysis unit 220, the throughput determination unit 240, and the retransmission described in the second embodiment are performed. The function of the rate determination unit 250 can be executed. Further, the CPU 290 can execute the functions of the packet size control unit 260 and the radio wave / noise status determination unit 280 by executing the program, for example. The CPU 290 corresponds to, for example, the information acquisition analysis unit 220, the throughput determination unit 240, the retransmission rate determination unit 250, the packet size control unit 260, and the radio wave / noise state determination unit 280.

  Further, the RAM 291 stores, for example, the packet size table 230 in the second embodiment. The RAM 291 corresponds to the packet size table 230, for example. Furthermore, the antenna 294 and the wireless unit 295 correspond to, for example, the wireless communication unit 210 in the second embodiment.

  Further, in the above-described embodiment, the example in which the radio wave intensity and noise intensity, the throughput, and the retransmission rate are calculated based on a radio signal or a radio packet in the downlink communication direction transmitted from the AP 100 to the terminal 200 has been described. Such information may be calculated based on, for example, a radio signal or a radio packet in the uplink communication direction transmitted from the terminal 200 to the AP 100. In this case, the information acquisition / analysis unit 120 of the AP 100 acquires the radio wave intensity and the noise intensity based on, for example, a radio signal transmitted from the terminal 200. In addition, the information acquisition / analysis unit 220 of the terminal 200 acquires a retransmission rate and throughput based on, for example, a wireless packet transmitted to the AP 100. The information acquisition / analysis unit 120 may acquire the retransmission rate and throughput from the terminal 200, and the information acquisition / analysis unit 220 may acquire the radio wave intensity and noise intensity from the AP 100.

  The above is summarized as an appendix.

(Appendix 1)
An information acquisition analysis unit for acquiring a retransmission rate indicating a throughput and a rate of retransmission based on packet data exchanged with other wireless communication devices;
Packet size table,
A packet size control unit that calculates a packet size based on the throughput and the retransmission rate, and stores the calculated packet size in the packet size table;
With a communication unit,
The packet size control unit determines the packet size with reference to the packet size table, outputs the determined packet size to the communication unit,
The wireless communication apparatus, wherein the communication unit performs communication based on the determined packet size.

(Appendix 2)
The packet size control unit performs the first packet size stored in the packet size table with respect to the first packet size when the throughput is equal to or lower than a first threshold and the retransmission rate is equal to or higher than a second threshold. The wireless communication apparatus according to appendix 1, wherein a second packet size smaller than the packet size of 1 is stored in the packet size table.

(Appendix 3)
The packet size control unit performs the first packet size stored in the packet size table with respect to the first packet size when the throughput is equal to or less than a first threshold and the retransmission rate is greater than a second threshold. The wireless communication apparatus according to appendix 1, wherein a second packet size larger than one packet size is stored in the packet size table.

(Appendix 4)
The information acquisition analysis unit determines an initial packet size based on the acquired throughput and the retransmission rate, stores the determined initial packet size in the packet size table,
The packet size control unit changes the packet size of the initial packet size based on the throughput and the retransmission rate with respect to the initial packet size stored in the packet size table, and changes the changed packet size to the packet size table. The wireless communication apparatus according to appendix 1, wherein the wireless communication apparatus is stored in a packet size table.

(Appendix 5)
The packet size control unit refers to the packet size table, acquires the packet size corresponding to the radio wave intensity and noise intensity acquired by the information acquisition analysis unit from the packet size table,
The wireless communication apparatus according to appendix 1, wherein the communication unit performs communication based on the acquired packet size.

(Appendix 6)
The other wireless communication device is a terminal device, the wireless communication device is an access point or a wireless base station device,
The wireless communication device according to appendix 1, wherein the communication unit transmits a wireless packet having the determined packet size to the terminal device.

(Appendix 7)
The wireless communication device according to appendix 6, wherein the wireless packet is an L1 (Layer 1) packet.

(Appendix 8)
The other wireless communication device is a terminal device, the wireless communication device is an access point or a wireless base station device,
The wireless communication apparatus according to claim 1, wherein the communication unit transmits a TCP (Transmission Control Protocol) packet having the determined packet size as a window size to another communication apparatus.

(Appendix 9)
The other wireless communication device is a terminal device, the wireless communication device is an access point or a wireless base station device,
The communication unit transmits a wireless packet having the determined packet size to the terminal device, and transmits a TCP (Transmission Control Protocol) packet having the determined packet size as a window size to another communication device. The wireless communication apparatus according to appendix 1.

(Appendix 10)
The other wireless communication device is an access point or a wireless base station device, the wireless communication device is a terminal device,
The communication unit transmits a TCP (Transmission Control Protocol) packet having the determined packet size as a window size to another communication device via the access point or a radio base station device. Wireless communication device.

(Appendix 11)
With other wireless communication devices,
A wireless communication system comprising a wireless communication device,
The wireless communication device
An information acquisition analysis unit for acquiring a retransmission rate indicating a throughput and a retransmission rate based on packet data exchanged with the other wireless communication device;
Packet size table,
A packet size control unit that calculates a packet size based on the throughput and the retransmission rate, and stores the calculated packet size in the packet size table;
With a communication unit,
The packet size control unit determines the packet size with reference to the packet size table, outputs the determined packet size to the communication unit, and the communication unit performs communication based on the determined packet size A wireless communication system.

(Appendix 12)
A communication method in a wireless communication apparatus having an information acquisition analysis unit, a packet size table, a packet size control unit, and a communication unit,
The information acquisition and analysis unit acquires a retransmission rate indicating a throughput and a retransmission ratio based on packet data exchanged with another wireless communication device,
The packet size control unit calculates a packet size based on the throughput and the retransmission rate, stores the calculated packet size in the packet size table,
The packet size control unit determines the packet size with reference to the packet size table, and outputs the determined packet size to the communication unit,
The communication method performs communication based on the determined packet size by the communication unit.

10: Wireless communication system 100: AP
110: Wireless communication unit 120: Information acquisition / analysis unit (information acquisition analysis unit)
130: Packet size table 140: Throughput determination unit 150: Retransmission rate determination unit 160: Packet size control unit 170: Wired communication unit 180: Radio wave / noise state determination unit 200: Terminal device 210: Wireless communication unit 220: Information acquisition / analysis Department (Information Acquisition and Analysis Department)
230: Packet size table 240: Throughput determination unit 250: Retransmission rate determination unit 260: Packet size control unit 280: Radio wave / noise status determination unit 300: Network

Claims (8)

An information acquisition analysis unit for acquiring a retransmission rate indicating a throughput and a rate of retransmission based on packet data exchanged with other wireless communication devices;
Packet size table,
A packet size control unit that calculates a packet size based on the throughput and the retransmission rate, and stores the calculated packet size in the packet size table;
With a communication unit,
The packet size control unit determines the packet size with reference to the packet size table, outputs the determined packet size to the communication unit,
The wireless communication apparatus, wherein the communication unit performs communication based on the determined packet size.   The packet size control unit performs the first packet size stored in the packet size table with respect to the first packet size when the throughput is equal to or lower than a first threshold and the retransmission rate is equal to or higher than a second threshold. The wireless communication apparatus according to claim 1, wherein a second packet size smaller than one packet size is stored in the packet size table.   The packet size control unit performs the first packet size stored in the packet size table with respect to the first packet size when the throughput is equal to or less than a first threshold and the retransmission rate is smaller than a second threshold. The wireless communication apparatus according to claim 1, wherein a second packet size larger than one packet size is stored in the packet size table. The other wireless communication device is a terminal device, the wireless communication device is an access point or a wireless base station device,
The wireless communication device according to claim 1, wherein the communication unit transmits a wireless packet having the determined packet size to the terminal device. The other wireless communication device is a terminal device, the wireless communication device is an access point or a wireless base station device,
The wireless communication apparatus according to claim 1, wherein the communication unit transmits a TCP (Transmission Control Protocol) packet having the determined packet size as a window size to another communication apparatus. The other wireless communication device is an access point or a wireless base station device, the wireless communication device is a terminal device,
2. The communication unit transmits a TCP (Transmission Control Protocol) packet having the determined packet size as a window size to another communication device via the access point or a radio base station device. Wireless communication device. With other wireless communication devices,
A wireless communication system comprising a wireless communication device,
The wireless communication device
An information acquisition analysis unit for acquiring a retransmission rate indicating a throughput and a retransmission rate based on packet data exchanged with the other wireless communication device;
Packet size table,
A packet size control unit that calculates a packet size based on the throughput and the retransmission rate, and stores the calculated packet size in the packet size table;
With a communication unit,
The packet size control unit determines the packet size with reference to the packet size table, outputs the determined packet size to the communication unit, and the communication unit performs communication based on the determined packet size A wireless communication system. A communication method in a wireless communication apparatus having an information acquisition analysis unit, a packet size table, a packet size control unit, and a communication unit,
The information acquisition and analysis unit acquires a retransmission rate indicating a throughput and a retransmission ratio based on packet data exchanged with another wireless communication device,
The packet size control unit calculates a packet size based on the throughput and the retransmission rate, stores the calculated packet size in the packet size table,
The packet size control unit determines the packet size with reference to the packet size table, and outputs the determined packet size to the communication unit,
The communication method performs communication based on the determined packet size by the communication unit.

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