JP2014155178A - Radio access point device, radio communication method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform efficient communication without wasting transmission resources at the time of transmission of data to a plurality of destinations.SOLUTION: A communication device notifies other communication devices of data transmission to be performed, receives a response to the notification, in order to multiplex and transmit data destined to a first another communication device from which the response is received and data destined to a second another communication device from which the response is not received.

Description

 The present invention relates to a communication apparatus that multiplexes and transmits data for a plurality of destinations.

  Conventionally, MIMO communication in which a wireless access point device (AP) having a plurality of transmitting antennas and a plurality of wireless stations (STA) each having a plurality of receiving antennas simultaneously communicate using the same frequency is known. . In addition, IEEE 802.11ac is being formulated as a next-generation wireless LAN standard, and MU-MIMO technology will be added in addition to the SU-MIMO technology previously used in IEEE 802.11n for significant speedup. is there. In MU-MIMO, data can be transmitted to a plurality of STAs at the same time, so there is an advantage that transmission efficiency is improved. In Patent Document 1, a multi-RTS (mRTS) frame is proposed as an application technique of a conventional Request To Send (RTS) frame. The mRTS method is a method for transmitting RTS frames to a plurality of destination STAs simultaneously.

  FIG. 13 is a diagram illustrating frame timing when performing MU-MIMO communication using an mRTS frame. When there is data to be transmitted to each STA, the AP notifies that there is a transmission request by sending an mRTS frame to each STA that is the destination of the data. Each STA that has received the mRTS frame notifies the AP that transmission has been permitted by sending a CTS (Clear To Send: CTS) frame to the AP. When propagation path conditions are good, such as when there is little interference between STAs, all CTS frames transmitted from each STA are received by the AP, and then the AP multiplexes data and transmits it to each STA. The STA that has received the data transmits a Block ACK (BA) frame to the AP as a confirmation for reception. On the other hand, if the AP cannot receive the CTS frame that was transmitted from the STA that received the mRTS frame (scheduled to be transmitted), the AP will not respond to the STA that could not receive the CTS frame, as in SU-MIMO. Control not to transmit data.

US Patent Application Publication No. 2010/0309871

  As described above, when the AP cannot receive the CTS frame from the STA that transmitted the mRTS frame, the AP does not transmit data to the STA. This will unnecessarily reduce data transmission opportunities, especially in the case of MU-MIMO, leading to wasteful transmission resources. That is, in MU-MIMO, data is not transmitted despite the large number of transmission resources, and there is a problem that the data transmission opportunity by the AP is unnecessarily reduced.

  The present invention has been made in view of the above problems, and an object of the present invention is to perform efficient communication without wasting transmission resources when transmitting data to a plurality of destinations.

  As a means for achieving the above object, a communication apparatus of the present invention comprises the following arrangement. That is, a notification means for notifying another communication apparatus that the communication apparatus transmits data, a reception means for receiving a response to the notification by the notification means, and a first reception of the response by the reception means Transmitting means for multiplexing and transmitting data addressed to another communication apparatus and data addressed to the second other communication apparatus for which the response has not been received by the receiving means.

  According to the present invention, when data is transmitted to a plurality of destinations, efficient communication can be performed without wasting transmission resources.

The figure which shows the functional block of a wireless access point apparatus (AP). The figure which shows the radio | wireless communications system by 1st thru | or 4th embodiment. The figure which shows the radio | wireless frame timing by 1st Embodiment. The figure which shows the radio | wireless frame timing by 2nd Embodiment. The figure which shows the radio | wireless frame timing by 3rd Embodiment. The figure which shows the radio | wireless frame timing by 4th Embodiment. The figure which shows the outline | summary of the data frame by 2nd Embodiment. The figure which shows AP operation | movement flowchart by 1st thru | or 4th embodiment. The figure which shows AP operation | movement flowchart of the data transmission process by 1st Embodiment. The figure which shows AP operation | movement flowchart of the data transmission process by 2nd Embodiment. The figure which shows AP operation | movement flowchart of the data transmission process by 3rd Embodiment. The figure which shows AP operation | movement flowchart of the data transmission process by 4th Embodiment. The figure which shows the mRTS radio | wireless frame timing in a prior art. The figure which shows the data transmission correspondence table | surface of AP.

[First Embodiment]
A first embodiment will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of functional blocks of a wireless access point device (AP) 101. As illustrated in FIG. This wireless access point device can operate in accordance with a wireless LAN (Local Area Network) standard defined by IEEE802.11. In FIG. 1, a wireless transmission / reception unit 102 transmits / receives wireless data using an 802.11 wireless LAN system. At that time, communication using SU-MIMO technology or MU-MIMO technology is possible. The RTS / mRTS frame (transmission request frame) transmission unit 103 and the CTS frame (transmission permission frame) reception unit 104 transmit an RTS (mRTS) / CTS sequence corresponding to the hidden terminal problem to one or more wireless stations (STAs). Run. The communication data storage unit 105 is a block for storing a communication history, and stores a communication history for each STA. Details will be described in a third embodiment and a fourth embodiment described later. The wireless communication control unit 106 is a block that controls transmission / reception messages of the wireless transmission / reception unit 102, and performs instructions for establishing and disconnecting a wireless link and transmission control of multiplexed data.

  The data multiplexing determining unit 107 acquires information on the MIMO system currently used by the own device from the wireless communication control unit 106, and determines whether to perform data multiplexing according to the acquired result. When MU-MIMO is used and there are multiple destination STAs, data is multiplexed. In addition, when MU-MIMO is used and the destination STA is single or SU-MIMO is used, data multiplexing is not performed. The data length determination unit 108 determines the data to be multiplexed by comparing the lengths of each data when using MU-MIMO and there are a plurality of destination STAs. Details will be described in the second embodiment. The multiplexed data generation unit 109 executes multiplexing processing based on the determination of the data multiplexing determination unit 107. All the functional blocks have a mutual relationship in terms of software or hardware. In addition, these functional blocks are examples, and a plurality of functional blocks may constitute one functional block, or any one of the functional blocks may be further divided into blocks that perform a plurality of functions.

  FIG. 2 is a diagram showing a data transmission / reception system according to this embodiment. In this embodiment, as shown in FIG. 2, it is composed of one AP and four STAs (STA1 to STA4, other communication devices). The AP having the configuration shown in FIG. 1 and STA1 to STA4 can communicate with each other using MU-MIMO or SU-MIMO. Area 201 and area 202 indicate wireless areas in which STA2 and STA4 can communicate, respectively. The wireless areas of STA1 and STA3 are omitted. The system shown in FIG. 2 includes an environment in which a hidden terminal problem can occur. Therefore, normal communication becomes possible by using the RTS (mRTS) / CTS sequence.

  FIG. 8 is a diagram showing an operational flowchart of the AP according to the present embodiment. FIG. 9 is a diagram showing a detailed operation flowchart of the data transmission processing step S809 in FIG. In FIG. 8, first, data to be transmitted to the terminals STA1 to STA4 is generated in the AP (S801). Thereafter, the data multiplexing determination unit 107 acquires information on the MIMO system currently used by the apparatus from the wireless communication control unit 106. When MU-MIMO is used (MU-MIMO of S802), preparations for transmitting mRTS frames are made. Then, the RTS / mRTS frame transmission unit 103 creates an mRTS frame including a value indicating how long the radio channel is occupied and the address of each destination STA (S803). The created mRTS frame passes through the wireless communication control unit 106 and is transmitted from the wireless transmission / reception unit 102 to each destination STA (S804). On the other hand, when using SU-MIMO (SU-MIMO of S802), the same processing as S803 and S804 is performed on the single destination STA, and the RTS frame is transmitted to the destination STA (S805). , S806).

  Each STA that has received the (m) RTS frame transmitted from the AP transmits a CTS frame to the AP as a response thereto. When the CTS frame reception period, which is a set fixed time, has passed (C807, Y), the CTS frame reception unit 104 notifies the data multiplexing determination unit 107 of the reception result of the CTS frame. The data multiplexing determining unit 107 that has received the notification of the reception result again performs the determination on the currently used MIMO system performed in S802 (S808). When using SU-MIMO (SU-MIMO in S808), radio communication control section 106 obtains the reception result of the CTS frame from CTS frame reception section 104 and determines whether to transmit data. When a CTS frame is received (Y in S810), it is determined to transmit data, and the wireless transmission / reception unit transmits data (S811). If a CTS frame has not been received (N in S810), it is determined not to transmit data, and the process ends. On the other hand, when MU-MIMO is used (MU-MIMO in S808), the process proceeds to S809. FIG. 9 is an operation flowchart of S809. In FIG. 9, the data multiplexing determining unit 107 determines to multiplex data regardless of the reception result of the CTS frame obtained from the CTS frame receiving unit 104 (S901). Then, the data multiplexed by the multiplexed data generation unit 109 is transmitted to each STA (addressed to the radio station) through the radio communication control unit 106 and the radio transmission / reception unit 102 (S901).

  FIG. 3 is a diagram illustrating an example of radio frame timing between the AP and the STA according to the present embodiment. The time axis proceeds from the left to the right in the figure. Also, in FIG. 3, MU-MIMO is used as a MIMO system, and as shown in FIG. 2, the system is configured with one AP and four STAs (N = 4). . Also, when STA1 to 4 send CTS frames or BA frames (data reception confirmation frames), they are sent sequentially from STA1 in round robin format, but the CTS frame return order by STA is in mRTS frames sent by AP It may be included. In FIG. 3, the AP receives a CTS frame from an STA (first other communication apparatus) other than STA2, while not receiving a CTS frame 301 from STA2 (second other communication apparatus). However, in FIG. 3, after the end of the CTS frame reception period, the AP sends data addressed to all STAs including data 302 addressed to STA2 (data addressed to the first other communication device and data addressed to the second other communication device). ) Is transmitted in a multiplexed manner. In this case, since STA2 has successfully received the data, it transmits the BA frame 303.

  FIG. 14A is a table showing “determination of the data multiplexing determination unit 107” based on “use MIMO system” and “reception availability of CTS frame” in the present embodiment. As shown in Table 1, when the MIMO system to be used is SU-MIMO, the AP does not transmit data unless it receives a CTS frame from the STA. On the other hand, when the MIMO system to be used is MU-MIMO, the AP multiplexes data to all STAs after waiting for a predetermined CTS frame reception period even if it does not receive CTS frames from all STAs. Send.

  As described above, when communication is performed with data multiplexed by MU-MIMO, even if the AP does not receive a CTS frame from the STA by the CTS frame reception period, the AP transmits data to all STAs. This increases the possibility of efficient communication without wasting transmission resources. For example, when the STA detects the wireless transmission of another network when transmitting the CTS frame, the method according to the present embodiment is effective because the CTS frame cannot be transmitted at a specified timing. In addition, the processing is divided between SU-MIMO and MU-MIMO. However, when MU-MIMO has only one destination STA, processing similar to SU-MIMO can be performed. The CTS frame reception period may be a predetermined time or may be variable depending on the system.

[Second Embodiment]
A second embodiment will be described with reference to the drawings. The data transmission / reception system according to the present embodiment includes one AP and four STAs (STA1 to STA4) as shown in FIG. 2, and the AP has functional blocks as shown in FIG. The operation flowchart of the AP according to the present embodiment is the same as that in FIG. 8 described in the first embodiment, but the data transmission process S806 is different. Therefore, a data transmission process S806 different from the first embodiment will be described with reference to FIG.

  When MU-MIMO is used as the current MIMO system, the data multiplexing determination unit 107 does not receive the CTS frame by the AP in the data length determination unit 108 after obtaining the reception result of the CTS frame from the CTS frame reception unit 104. Pass STA information. The data length determining unit 108 determines whether or not the actual data length addressed to the STA for which no CTS frame is received by the AP is the longest among the multiplexed data (S1001).

  The determination in S1001 will be described with reference to FIG. FIG. 7 is a schematic diagram of a data frame, and shows a state of data multiplexed by the multiplexed data generation unit 109. Data from STA1 to 4 are shown in order from the top. Here, padding data is used in order to align the lengths of actual data having various lengths. FIG. 7A shows the state in which the actual data addressed to STA3 is the longest, and FIG. 7B shows the state in which the actual data addressed to STA2 is the longest. Assuming that the STA that does not receive the CTS frame by the AP is STA2, the data length determination unit 108 passes information on whether or not the length of the actual data addressed to STA2 is the longest to the data multiplexing determination unit 107.

  When the data multiplex determination unit 107 receives information from the data length determination unit 108 that the data length addressed to STA2 is not the longest as shown in FIG. 7A (N in S1001), the data multiplex determination unit 107 stores data addressed to all STAs. It decides to multiplex and transmit (S1002). On the other hand, when receiving the information that the data length addressed to STA2 is the longest (Y in S1001) from the data length determination unit 108, the data multiplexing determination unit 107 receives the CTS by the AP as shown in FIG. It is determined to multiplex and transmit data addressed to the STA with frame reception (S1003). That is, it is determined not to multiplex data addressed to STA2. This is because, although the presence of STA2 has not been confirmed, adjusting the length of multiplexed data in accordance with STA2 to transmit data to STA2 may not be an efficient communication. The data multiplexed by the multiplexed data generation unit 109 is transmitted to each STA through the radio communication control unit 106 and the radio transmission / reception unit 102 after a predetermined CTS frame reception period has elapsed (S1002, S1003). .

  FIG. 4 is a diagram illustrating an example of radio frame timing between the AP and the STA according to the present embodiment. Descriptions other than the wireless frame timing according to the present embodiment are the same as those in FIG. FIG. 4 shows a case where the data length destined for STA2 is the longest as shown in FIG. 7B in a situation where the AP has not received the CTS frame 401 from STA2. In this case, the AP multiplexes and transmits data destined for all STAs other than the data 402 destined for STA2. Since data is not transmitted to STA2, STA2 does not transmit BA frame 403.

  Thus, when performing communication by multiplexing data with MU-MIMO, if the actual data length of an STA that does not receive a CTS frame by the AP is not the longest, the AP transmits data to all STAs. This increases the possibility of efficient communication without wasting transmission resources. For example, when the STA detects the wireless transmission of another network when transmitting the CTS frame, the method according to the present embodiment is effective because the CTS frame cannot be transmitted at a specified timing. If the AP does not receive CTS frames from multiple STAs, data multiplexing is performed only when the actual data length for such STAs is shorter than the actual data length of the STA that was able to receive the CTS frame. May be transmitted.

[Third Embodiment]
A third embodiment will be described with reference to the drawings. The data transmission / reception system according to the present embodiment includes one AP and four STAs (STA1 to STA4) as shown in FIG. 2, and the AP has functional blocks as shown in FIG. The operation flowchart of the AP according to the present embodiment is the same as that in FIG. 8 described in the first embodiment, but the data transmission process S806 is different. Therefore, a data transmission process S806 different from the first embodiment will be described with reference to FIG.

  When MU-MIMO is used as the current MIMO system, the data multiplexing determination unit 107 does not receive the CTS frame by the AP in the communication data storage unit 105 after obtaining the reception result of the CTS frame from the CTS frame reception unit 104. Pass STA information. The communication data storage unit 105 stores the reception result of the previous CTS frame and BA frame by the AP as history data for each STA. The data multiplexing determination unit 107 determines whether or not the previous CTS frame has been successfully received with respect to the STA in which no CTS frame is received by the AP with reference to the history data stored in the communication data storage unit 105 (S1101). . If the previous CTS frame has been successfully received (Y in S1101), the data multiplexing determination unit 107 determines to multiplex and transmit data destined for all STAs (S1102). On the other hand, if the previous CTS frame has not been successfully received (N in S1101), it is determined to multiplex and transmit data addressed to the STA where the AP receives the CTS frame (S1103). This is because the STA that has not received the CTS frame by the AP in the previous time can be determined to be in an environment where data cannot be received. The data multiplexed by the multiplexed data generation unit 109 is transmitted to each STA through the radio communication control unit 106 and the radio transmission / reception unit 102 after a predetermined CTS frame reception period has elapsed (S1102, S1103). . Thereafter, the CTS frame reception results of all STAs are stored in the history data, and prepared for the next transmission (S1104).

  FIG. 5 is a diagram illustrating an example of radio frame timing between the AP and the STA according to the present embodiment. Descriptions other than the wireless frame timing according to the present embodiment are the same as those in FIG. In FIG. 5, the AP does not receive the CTS frame 502 of STA2, but makes a determination based on the reception history of the CTS frame, and since the CTS frame 501 was received last time, the data 503 addressed to STA2 is multiplexed and transmitted. It shows how you can do it.

  FIG. 14B is a table showing “determination of the data multiplexing determination unit 107” based on “use MIMO system” and “reception availability of CTS frame” in the present embodiment. As shown in Table 2, regardless of whether the MIMO system used is SU-MIMO or MU-MIMO, if there is a previous CTS frame reception history for an STA that does not receive a CTS frame by the AP, the AP will The data addressed to the STA is also multiplexed and transmitted.

  In this way, when MU-MIMO multiplexes data for communication, if there is a previous CTS frame reception history for an STA that does not receive a CTS frame by the AP, the AP also multiplexes data destined for such STA To do. On the other hand, if there is no previous CTS frame reception history for an STA that has not received a CTS frame by the AP, the AP determines that such STA cannot receive data and does not multiplex data. This increases the possibility that more efficient communication can be performed without wasting transmission resources. In particular, it is a feature of the method according to the present embodiment that control based on actual results is possible and more realistic control is possible. Further, when the AP does not receive CTS frames from a plurality of STAs, it may be handled by not multiplexing data addressed to such a plurality of STAs. In the above description, the previous CTS frame reception history is referred to, but it is also possible to refer to a history of a certain period.

[Fourth Embodiment]
A third embodiment will be described with reference to the drawings. The data transmission / reception system according to the present embodiment includes one AP and four STAs (STA1 to STA4) as shown in FIG. 2, and the AP has functional blocks as shown in FIG. The operation flowchart of the AP according to the present embodiment is the same as that in FIG. 8 described in the first embodiment, but the data transmission process S806 is different. Therefore, data transmission processing S806 different from the first embodiment will be described with reference to FIG.

  When MU-MIMO is used as the current MIMO system, the data multiplexing determination unit 107 does not receive the CTS frame by the AP in the communication data storage unit 105 after obtaining the reception result of the CTS frame from the CTS frame reception unit 104. Pass STA information. As described in the third embodiment, the communication data storage unit 105 stores the reception results of the previous CTS frame and BA frame by the AP as history data for each STA. Note that the BA frame includes a reception confirmation for each of the aggregated data groups. Here, a reception error rate is calculated from the reception history of the BA frame, and data multiplexing is determined based on the calculated error rate. The data multiplex determination unit 107 calculates a reception error rate with reference to the previous BA frame reception history for the STA that has not received the CTS frame by the AP stored in the communication data storage unit 105 (S1201). Then, when the reception error rate is 50% or less (Y in S1201), the data multiplexing determining unit 107 determines to multiplex and transmit data addressed to all terminals (S1202). On the other hand, if the reception error rate is greater than 50% (N in S1201), it is determined to multiplex and transmit data addressed to the STA that has received the CTS frame (S1203). The data multiplexed by the multiplexed data generation unit 109 is transmitted to each STA through the radio communication control unit 106 and the radio transmission / reception unit 102 after a predetermined CTS frame reception period has elapsed (S1202, S1203). . After that, the error rate or BA frame of all STAs is saved and prepared for the next opportunity (S1204).

  FIG. 6 is a diagram illustrating an example of radio frame timing between the AP and the STA according to the present embodiment. Descriptions other than the wireless frame timing according to the present embodiment are the same as those in FIG. In FIG. 6, the AP has not received the CTS frame 602 of STA2, but the determination is also made based on the reception history of the BA frame 601, and the BA frame 601 was received last time and the reception error rate is determined to be 50% or less. It shows a state where data 603 addressed to STA2 can be multiplexed and transmitted.

  FIG. 14C is a table showing “determination of the data multiplex determination unit 107” based on “used MIMO system” and “reception availability of CTS frame”. As shown in Table 3, regardless of whether the MIMO system used is SU-MIMO or MU-MIMO, if there is a previous BA frame reception history for an STA that does not receive a CTS frame by the AP, the AP will The data addressed to the STA is also multiplexed and transmitted.

  In this way, when communicating with MU-MIMO by multiplexing data, if the error rate up to the previous time determined from the BA frame reception history is lower than the predetermined threshold for STAs that do not receive CTS frames by AP The AP also multiplexes data destined for such STAs. Conversely, for STAs that do not receive CTS frames by the AP, if the error rate up to the previous time is higher than a predetermined threshold, the AP determines that such STAs cannot receive data and does not multiplex data . This increases the possibility of more efficient communication without wasting transmission resources. In particular, it is a feature of the method according to the present embodiment that control based on actual results is possible and more realistic control is possible. If the AP has not received CTS frames from a plurality of STAs, it may be handled by not multiplexing data addressed to such a plurality of STAs. Here, the previous reference error rate is set to 50%, but the value of the reference error rate can be changed, or the error rate history for a certain period can be determined.

  According to the above embodiment, even when an event such as the (m) RTS frame does not arrive from the AP and the CTS frame cannot be transmitted because the terminal of the other network is performing data communication in the STA, Data communication can be performed with the target communication device. In other words, the system is configured to select the data transmission control for the STA that did not receive the CTS frame by the AP according to the MIMO system used by the AP, so efficient communication can be performed without wasting transmission resources. The effect is obtained.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (11)

A communication device,
Notification means for notifying another communication device that the communication device transmits data;
Receiving means for receiving a response to the notification by the notification means;
The data addressed to the first other communication device for which the response has been received by the receiving means and the data addressed to the second other communication device for which the response has not been received by the receiving means are multiplexed and transmitted. A transmission means;
A communication apparatus comprising: The notifying means transmits a transmission request frame to the other communication device;
The receiving means receives a transmission permission frame for the transmission request frame from the other communication device;
The transmission means receives the data addressed to the first other communication device from which the transmission permission frame has been received by the reception means and the transmission by the reception means after a predetermined time set in the reception means has elapsed. The communication apparatus according to claim 1, wherein the communication apparatus multiplexes and transmits data addressed to the second other communication apparatus for which the permission frame has not been received. The actual data length of the data addressed to the second other communication device for which the transmission permission frame has not been received by the receiving means and the actual data length of the data addressed to the first other communication device for which the transmission permission frame has been received. A data length judging means for comparing the data length,
The transmission means does not receive the transmission permission frame by the reception means when the actual data length of data addressed to the second other communication device for which the transmission permission frame has not been received by the reception means is short. When it is determined that the data addressed to the second other communication device is multiplexed, and the actual data length of the data addressed to the second other communication device in which the transmission permission frame has not been received by the receiving means is long 3. The communication apparatus according to claim 2, further comprising: not to multiplex data addressed to the second other communication apparatus for which the transmission permission frame has not been received by the receiving unit. Communication data storage means for storing at least the previous communication history in each of the other communication devices;
The transmission means determines whether to multiplex data addressed to the second other communication device for which the transmission permission frame has not been received by the reception means by referring to the communication data storage means. Item 3. The communication device according to Item 2. The communication history stored in the communication data storage means is a reception history of a transmission permission frame for a previous transmission request frame,
When there is a reception history of the transmission permission frame with respect to the second other communication device in which the transmission permission frame has not been received by the reception unit, the transmission unit is addressed to the second other communication device. 5. The communication apparatus according to claim 4, wherein it is determined to multiplex data. The communication history stored in the communication data storage means is a reception history of a data reception confirmation frame for the previous data communication,
The transmission means is directed to the second other communication apparatus when there is a reception history of the data reception confirmation frame for the second other communication apparatus in which the transmission permission frame has not been received by the reception means. The communication apparatus according to claim 4, wherein it is determined to multiplex the data.   The transmission means calculates a reception error rate based on the data reception confirmation frame, and the reception error rate of the second other communication apparatus in which the transmission permission frame is not received by the reception means is less than a threshold value. 7. The communication device according to claim 6, wherein when it is low, it determines to multiplex data addressed to the second other communication device.   8. The wireless access point device according to claim 1, wherein the wireless access point device operates in accordance with a wireless LAN (Local Area Network) standard defined by IEEE 802.11.   9. The transmission means multiplexes and transmits data addressed to the first other communication device and data addressed to the second other communication device by MU-MIMO technology. The communication device according to any one of the above. A communication device control method comprising:
A notification step of notifying another communication device that the communication device transmits data;
A receiving step of receiving a response to the notification in the notification step;
The data addressed to the first other communication device for which the response was received in the reception step and the data addressed to the second other communication device for which the response was not received in the reception step are multiplexed and transmitted. Sending process;
A method for controlling a communication apparatus, comprising:   A program for causing a computer to execute the control method according to claim 10.

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