Access point device, control method of access point device, and program

Abstract

To suitably perform data communication using a RU.SOLUTION: An AP transmits a trigger frame including information in which a plurality of RUs and AIDs of a plurality of STAs are associated with each other. The AP receives a signal from the one STA through the RU associated with the AID of the one STA. Here, the received signal is transmitted with transmission power determined using both second information and reception signal intensity, the second information can be acquired by analyzing the trigger frame, and the reception signal intensity is intensity of a signal communicated between the one STA and the AP. Reception control of the AP receives a signal transmitted from the STA with first transmission power, when the reception signal intensity is first intensity, and receives a signal transmitted from the STA with second transmission power larger than the first transmission power, when the reception signal intensity is second intensity smaller than the first intensity.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an access point device that communicates using the OFDMA system. [Background technology]

[0002] Communication devices that perform wireless communication in accordance with the IEEE802.11 series are in widespread use. Communication devices that comply with the IEEE802.11 series use an access method called CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). CSMA / CA specifies that before transmitting a signal, carrier sense must be performed to measure the radio wave strength of the frequency channel through which the signal is transmitted. In carrier sense, the radio wave strength is measured in a 20 MHz width, which is one frequency channel specified in IEEE802.11.

[0003] If the result of the carrier sense shows that the measured radio wave strength does not exceed a predetermined threshold, a signal is transmitted, and if the measured radio wave strength is equal to or greater than the predetermined threshold, a signal is not transmitted.

[0004] Meanwhile, IEEE802.11ax is being studied by the IEEE as a standard following IEEE802.11ac (Patent Document 1). In IEEE802.11ax, a single frequency channel will be further divided into multiple frequency bands, and different devices will be able to communicate simultaneously using each of the multiple frequency bands. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-165676 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when one frequency channel is further divided into a plurality of frequency bands and different devices communicate simultaneously using each of the plurality of frequency bands, there may be cases where only a portion of the frequency bands is used for communication.

[0007] For example, in a system that divides one frequency channel into four frequency bands, there may be a case where there are only two devices transmitting data signals at a given time, and in such a case, only two of the four frequency bands may be used.

[0008] In such a case, if the transmission power per unit frequency (transmission power density) of each device is the same as the transmission power density when transmitting signals using the entire frequency band of one frequency channel, the transmission power of the entire frequency channel will be approximately halved.

[0009] Therefore, when another communication device performs carrier sensing in CSMA / CA, the transmission power of the entire frequency channel is low, so that it is not possible to measure radio wave strength exceeding a specified threshold, and the other communication device may end up transmitting a signal.

[0010] When another communication device transmits a signal, radio interference occurs, resulting in an error. In view of the above problem, an object of the present invention is to provide a method for suitably transmitting data using a resource unit. [Means for solving the problem]

[0011] The access point device according to one aspect of the present invention is an access point device that performs communication in accordance with the IEEE 802.11 series standard using an OFDMA (Orthogonal Frequency Division Multiple Access) method, and has a plurality of resource units obtained by dividing a channel of a predetermined frequency bandwidth and AIDs (Association Identification Data) that are identification information of a plurality of station devices. a transmission control means for performing transmission control so as to transmit a trigger frame including information associating an AID with an AID of one of the plurality of station devices; and a reception control means for performing reception control so as to receive a signal from the one station device in the trigger frame through a resource unit associated with an AID of the one station device among the plurality of station devices after transmitting the trigger frame, the signal received by the reception control being transmitted at a transmission power determined using both second information and a received signal strength, the second information being obtainable by analyzing the trigger frame and being used to determine a transmission power in the one station device when the one station device transmits a signal, the received signal strength being a strength of a signal communicated between the one station device and the access point device, and the reception control being characterized in that, if the received signal strength is a first strength, the signal transmitted from the one station device is received using a first transmission power, and if the received signal strength is a second strength smaller than the first strength, the signal transmitted from the one station device is received using a second transmission power larger than the first transmission power. Effect of the Invention

[0012] According to one aspect of the present invention, when a signal is transmitted in a part of a frequency band in a frequency channel including a plurality of frequency bands, the signal can be transmitted suitably. [Brief description of the drawings]

[0013] [Figure 1] Network Diagram [Diagram 2]Hardware configuration diagram of communication device [Diagram 3] Diagram showing the relationship between frequency and RU [Figure 4] Diagram showing the relationship between frequency and RU [Diagram 5] Flowchart implemented by the communication device [Figure 6] Flowchart implemented by the communication device [Figure 7] Flowchart implemented by base station DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Embodiment 1> 1 shows a communication system in this embodiment. A base station 110 is an access point conforming to the IEEE802.11 series, and forms a wireless network 100. In this embodiment, the base station 110 forms the wireless network 100 conforming to IEEE802.11ax, and performs wireless communication conforming to IEEE802.11ax. Here, IEEE is an abbreviation for The Institute of Electrical and Electronics Engineers, Inc.

[0015] A communication device 101 is a child station participating in a wireless network 100 formed by a base station 110. In the wireless network 100, the communication device 101 performs wireless communication with the base station 110 in compliance with IEEE802.11ax. Similarly, a plurality of communication devices 102 also participate in the wireless network 100 as child stations, and perform wireless communication with the base station 110 in compliance with IEEE802.11ax.

[0016] The communication device 103 is a legacy terminal that does not support IEEE802.11ax, and performs wireless communication in accordance with at least one of IEEE802.11a, b, g, n, and ac.

[0017] Note that the communication device 103, which is a legacy terminal, communicates using the DSSS or OFDM system, whereas the communication devices 101, 102 and the base station 110 communicate using the OFDMA system. Therefore, even if the communication device 103 receives a signal from the communication devices 101, 102 and the base station 110, it cannot recognize the signal as a data signal. Note that DSSS is an abbreviation for Direct Sequence Spread Spectrum. Furthermore, OFDM is an abbreviation for Orthogonal Frequency Division Multiplexing. Furthermore, OFDMA is an abbreviation for Orthogonal Frequency-Division Multiple Access.

[0018] Therefore, the communication device 103, which is a legacy terminal, prevents interference by using an access method called Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA).

[0019] Specifically, before transmitting a signal, the communication device 103 performs carrier sense to measure the radio wave strength of the frequency channel through which the signal is transmitted. In the carrier sense, the radio wave strength is measured in a 20 MHz width, which is one frequency channel defined by IEEE802.11.

[0020] If the measured radio wave strength does not exceed a predetermined threshold, it is determined that no other communication device is communicating on that frequency channel, and communication device 103 transmits a signal. On the other hand, if the measured radio wave strength is equal to or greater than the predetermined threshold, it is determined that another communication device is communicating on that frequency channel, and communication device 103 does not transmit a signal, thereby preventing interference with other communication devices.

[0021] 2 shows a hardware configuration of the communication device 101. It is assumed that the base station 110 and the other communication device 102 also have a similar hardware configuration.

[0022] The storage unit 201 is configured with memories such as ROM and RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. Note that, in addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used as the storage unit 201. Furthermore, the storage unit 201 may include multiple memories.

[0023] The control unit 202 is configured with a processor such as a CPU or an MPU, and controls the entire communication device 101 by executing a program stored in the storage unit 201. The control unit 202 may control the entire communication device 101 in cooperation with the program stored in the storage unit 201 and an OS (Operating System). The control unit 202 may also include multiple processors such as multi-core processors, and control the entire communication device 101 using the multiple processors.

[0024] Furthermore, the control unit 202 controls the functional unit 203 to execute predetermined processing such as imaging, printing, and projection. The functional unit 203 is hardware for the communication device 101 to execute predetermined processing. For example, if the communication device 101 is a camera, the functional unit 203 is an imaging unit and performs imaging processing. For example, if the communication device 101 is a printer, the functional unit 203 is a printing unit and performs printing processing. For example, if the communication device 101 is a projector, the functional unit 203 is a projection unit and performs projection processing. Data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data received from another communication device via a communication unit 206 described later.

[0025] The input unit 204 receives various operations from the user. The output unit 205 outputs various types of information to the user. Here, the output by the output unit 205 includes at least one of display on a screen, audio output by a speaker, vibration output, and the like. Note that both the input unit 204 and the output unit 205 may be realized by one module, such as a touch panel.

[0026] The communication unit 206 controls wireless communication conforming to the IEEE802.11 series, TCP / IP communication, etc. The communication unit 206 also controls an antenna 207 to transmit and receive wireless signals for wireless communication. The communication device 101 communicates content such as image data, document data, and video data with other communication devices via the communication unit 206.

[0027] Next, a communication method of IEEE802.11ax currently under consideration will be described with reference to FIG. 3. In addition to the conventional method of using one entire frequency channel for communication, the following communication method is being considered for IEEE802.11ax. That is, it is being considered to divide the 20 MHz width that has been used as one frequency channel into multiple frequency bands, and to have different communication devices simultaneously use each of these multiple frequency bands for communication. Here, each of the multiple frequency bands is called an RU (Resource Unit). In this embodiment, it is assumed that one frequency channel 302 (20 MHz width) is divided into four, and one RU 303 is 5 MHz wide.

[0028] To allow multiple communication devices to use multiple RUs simultaneously, the access point transmits a trigger frame (TF) 301. A trigger frame is a transmission permission for one or multiple communication devices. The trigger frame includes information on the communication device to be assigned to each RU. Specifically, the trigger frame includes a list that associates RUs with AIDs, which are identification information for the communication devices. AID is an abbreviation for Association Identifier.

[0029] A communication device permitted to transmit by the trigger frame transmits a data frame signal 304 in a designated RU when the SIFS time has elapsed after receiving the trigger frame. Here, SIFS stands for Short Inter Frame Space, and is the minimum waiting time before transmitting a signal. Note that AIFS, DIFS, PIFS, EIFS, etc. may be used instead of SIFS. Note that AIFS stands for Arbitration Inter Frame Space, and DIFS stands for Distributed Inter Frame Space. Also, PIFS stands for Point Inter Frame Space, and EIFS stands for Extended Inter Frame Space. Note that when multiple communication devices transmit data signals, in IEEE802.11ax, communication is performed using the OFDMA method to improve frequency utilization efficiency.

[0030] In addition, the transmission power (transmission power density) per unit frequency width of a signal transmitted by each communication device that is permitted to transmit is the same as the transmission power density when communicating using the entirety of one frequency channel. Therefore, the transmission power when transmitting a signal using one RU is lower than the transmission power when communicating using the entirety of one frequency channel. As a result, even if, for example, four communication devices each transmit a signal using an RU, the transmission power per frequency channel can be made equivalent to the transmission power when communicating using the entirety of one frequency channel. Therefore, it is possible to prevent the transmission power per frequency channel from becoming too large, for example, causing excessive interference with other networks or exceeding the power specified by law.

[0031] IEEE802.11ax also allows communication using multiple frequency channels in parallel. Figure 4 shows a case where communication is performed using four frequency channels. In this case, 16 RUs can be used.

[0032] FIG. 5 shows a flowchart of the flow of processing that is realized by the control unit 202 reading and executing a program stored in the storage unit 201 when the communication device 101 transmits a data signal.

[0033] At least a part of the flowchart shown in Fig. 5 may be realized by hardware. In the case of hardware realization, for example, a specific compiler may be used to automatically generate a dedicated circuit on an FPGA from a program for realizing each step. FPGA is an abbreviation for Field Programmable Gate Array. Also, a gate array circuit may be formed in the same manner as an FPGA to realize the hardware. Also, it may be realized by an ASIC (Application Specific Integrated Circuit).

[0034] First, the communication device 101 waits for a trigger frame from the base station 110 (S501). When the trigger frame is received (Yes in S501), the communication device 101 transmits a data signal after a SIFS time has elapsed (S502). Here, the communication device 101 transmits the data signal in the RU for the communication device 101 specified by the trigger frame.

[0035] Then, in parallel with transmitting the data signal, the communication device 101 checks the radio wave strength in the entire frequency channel that the communication device 101 is using to transmit the signal (S503). This check is performed by the communication unit 206 of the communication device 101 receiving while transmitting at the same time, and checking the radio wave strength in the entire frequency channel that the communication device 101 is using to transmit the signal.

[0036] In addition, if the communication unit 206 of the communication device 101 has a separate transmitter and receiver, the transmitter transmits the data signal, and the receiver checks the radio wave strength over the entire frequency channel that the communication device 101 is using to transmit the signal.

[0037] Furthermore, in the above-mentioned confirmation of radio wave strength, the confirmation of radio wave strength in the entire frequency channel may be limited to the data signal wirelessly communicating with base station 110. This is achieved by calculating the sum of the radio wave strengths of the data signals received at each RU.

[0038] If the result of the check is that the radio wave strength in the entire frequency channel is less than the predetermined threshold (No in S504), the communication device 101 increases the transmission power and transmits the data signal (S505). Here, the communication device 101 increases the power by the amount that the radio wave strength in the entire frequency channel does not satisfy the predetermined threshold, and transmits the data signal.

[0039] The above-mentioned predetermined threshold value is the same as the predetermined threshold value used by the communication device 103 during carrier sensing.

[0040] If the radio wave strength in the entire frequency channel is less than a predetermined threshold, when the communication device 103 performs carrier sense, it determines that no other communication device is communicating in that frequency channel, and the communication device 103 transmits a signal. If the communication device 103 transmits a signal, it may interfere with the signal transmitted by the communication device 101, causing an error. Therefore, the communication device 101 increases the transmission power of the signal to increase the radio wave strength in the entire frequency channel. This increases the likelihood that the carrier sense of the communication device 103 will estimate that another communication device is communicating in that frequency channel, and increases the probability that the communication device 103 will not transmit a signal. As a result, it is possible to suppress the occurrence of errors due to interference.

[0041] Furthermore, there are two possible methods for communication apparatus 101 to increase transmission power. The first method is to increase the transmission power density transmitted in the RU for communication apparatus 101. The second method is to transmit signals in other RUs in addition to the RU for communication apparatus 101. In this case, communication apparatus 101 may transmit, in the other RU, the same data as that transmitted in the RU for communication apparatus 101, or may transmit data different from that transmitted in the RU for communication apparatus 101, or may transmit dummy data.

[0042] According to the first method, since the transmission power of the data signal is increased, it is possible to obtain an effect of further improving the communication quality. Also, according to the second method, it is possible to increase the transmission power even in a case where an upper limit is set on the transmission power density transmitted from one RU due to, for example, hardware limitations or legal limitations.

[0043] Which of these methods is used may be determined in advance, or may be switched depending on the situation. For example, even if the transmission power density is increased within the limits of hardware and laws, the second method may be used if the radio wave intensity in the entire frequency channel does not reach a predetermined threshold, and the first method may be used otherwise. Even when the second method is used, the transmission power density in the RU for the communication device 101 may be increased as appropriate.

[0044] On the other hand, if the radio wave intensity in the entire frequency channel is equal to or greater than the predetermined threshold (Yes in S504), the communication device 101 continues transmitting the data signal without increasing the transmission power (S506).

[0045] When the transmission of the data signal is completed, the communication device 101 receives an Ack, which is an acknowledgment for the data signal, from the base station (S507). Here, the Ack is transmitted using one entire frequency channel. The Ack also serves as an acknowledgment for a data signal transmitted from another communication device 102 via another RU in synchronization with the transmission of the data signal by the communication device 101.

[0046] Then, the process shown in Fig. 5 ends. If data to be transmitted by the communication device 101 occurs, or if data to be transmitted remains, the process returns to the beginning of Fig. 5.

[0047] In addition, in S503, instead of checking the radio wave strength in the entire frequency channel, the number of RUs not being used for signal transmission may be determined by checking the usage status of each RU. In this case, in S504, the communication device 101 determines whether the number of RUs not being used for signal transmission is equal to or greater than a predetermined value. In addition, the predetermined value is set so that the radio wave strength in the entire frequency channel is less than a predetermined threshold value when the number of unused RUs is equal to or greater than the predetermined value. Therefore, when the number of unused RUs is equal to or greater than the predetermined value, the radio wave strength in the entire frequency channel is equal to or greater than the predetermined threshold value.

[0048] If the result of the determination in S504 is that the number of RUs not being used for signal transmission is equal to or greater than a predetermined value, the process proceeds to S505, and if the number is less than the predetermined value, the process proceeds to S506. In this manner, the same effect can be obtained.

[0049] Furthermore, in this case, in S505, the increase in transmission power may be controlled according to the number of RUs that are not being used to transmit signals. For example, if it is determined that two of the four RUs are not being used, the transmission power is doubled, and if it is determined that three of the four RUs are not being used, the transmission power is quadrupled. Note that if the transmission power cannot be quadrupled due to hardware or legal restrictions of the communication device 101, the maximum transmission power that satisfies these restrictions may be used.

[0050] This makes it possible to suppress the occurrence of errors due to interference with other communication devices by suppressing the transmission of signals from other communication devices while taking into consideration the balance with the transmission power when communicating using an entire frequency channel. That is, it is possible to prevent the transmission power in one frequency channel from becoming too large, for example, causing excessive interference with communications in other networks or exceeding the power limit set by law, and also to prevent interference with other communication devices.

[0051] Also, instead of determining the number of RUs not used for signal transmission, the number of RUs used for signal transmission may be determined. Even in this case, the same effect can be obtained by appropriately determining the predetermined value, and proceeding to S506 if the number of RUs used for signal transmission is equal to or greater than the predetermined value, and proceeding to S505 if the number is less than the predetermined value.

[0052] <Embodiment 2> In the first embodiment, the communication device 101 measures the signal strength and the usage status of the RU in parallel with the transmission of the data signal. In the second embodiment, the communication device 101 checks the usage status of the RU based on information included in the trigger frame.

[0053] In the second embodiment, the system configuration and the hardware configuration of each device are similar to those in the first embodiment, so a description thereof will be omitted here.

[0054] FIG. 6 shows a flowchart of the flow of processing that is realized by the control unit 202 reading and executing a program stored in the storage unit 201 when the communication device 101 transmits a data signal.

[0055] First, the communication device 101 waits for a trigger frame from the base station 110 (S601). When the trigger frame is received (Yes in S601), the communication device 101 analyzes the trigger frame and determines the number of RUs used to transmit a data signal (S602). As described in the first embodiment, the trigger frame includes a list in which AIDs, which are identification information of communication devices permitted to transmit, are associated with RUs. Therefore, the communication device 101 can determine the number of RUs used to transmit a data signal based on the trigger frame.

[0056] If the number of RUs used to transmit the signal is equal to or greater than the predetermined value (Yes in S603), the communication device 101 transmits the data signal at the same transmission power as in S502 in Fig. 5 (S604). On the other hand, if the number of RUs used to transmit the signal is less than the predetermined value (No in S603), the communication device 101 transmits the data signal at a transmission power higher than the transmission power in S604 (S605).

[0057] For example, if the predetermined value is 3, and it is determined that 3 of 4 RUs are in use and 1 RU is not in use, transmission is performed at the same transmission power density as when communication is performed using one entire frequency channel. Therefore, the transmission power of communication device 101 is about 1 / 4 of that when communication is performed using one entire frequency channel.

[0058] Also, if it is determined that two of the four RUs are in use and two RUs are not in use, the transmission power density is doubled. Therefore, the transmission power of the communication device 101 in this case is twice the transmission power in S502.

[0059] Furthermore, if it is determined that one of the four RUs is in use and three RUs are not in use, the transmission power density is increased by four times. Therefore, the transmission power of the communication device 101 in this case is four times the transmission power in S502. Note that if the transmission power cannot be increased fourfold due to hardware restrictions of the communication device 101 or legal restrictions, the maximum transmission power that satisfies these restrictions may be used.

[0060] When the transmission of the data signal is completed, the communication device 101 receives an Ack, which is an acknowledgement to the data signal, from the base station (S606). After that, the process shown in Fig. 6 ends. Note that if data to be transmitted by the communication device 101 occurs or if data to be transmitted remains, the process returns to the beginning of Fig. 6.

[0061] In this way, the communication device 101 can control the transmission power based on the information included in the trigger frame, thereby suppressing the occurrence of errors due to interference.

[0062] Note that there may be cases where each communication device uses an RU in an autonomous and distributed manner, and base station 110 does not specify the device that uses the RU. In such a case, base station 110 assigns an AID value (e.g., 0) to the trigger frame indicating that the device that uses the RU is not specified. Base station 110 may not specify the device for all RUs, or may not specify the device for some RUs.

[0063] If the device to be used is not specified for at least some of the RUs, the communication device 101 cannot determine from the trigger frame whether a signal is to be transmitted to the RU for which the device to be used is not specified. Therefore, in such a case, the processing shown in the first embodiment may be performed, and otherwise the processing may be switched to the processing shown in the second embodiment.

[0064] Furthermore, if the AID information included in the trigger frame cannot be obtained, the process shown in embodiment 1 may be performed, and if not, the process shown in embodiment 2 may be performed, or the above-mentioned switching process may be performed. If the AID information included in the trigger frame cannot be obtained, this may be because the AID information was not included in the trigger frame in the first place, or because the AID information included in the trigger frame could not be obtained due to a communication error.

[0065] As a result, when the usage status of the RU can be confirmed based on the information included in the trigger frame, power control can be performed based on the information in the trigger frame, and when the usage status cannot be confirmed, power control can be performed based on the measurement results of the radio wave strength and the usage status of the RU. Therefore, it is possible to perform appropriate power control processing according to the trigger frame.

[0066] <Embodiment 3> In the first and second embodiments, the communication device 101 checks the signal strength and the usage status of the RU. In the third embodiment, the base station 110 determines the transmission power of each communication device based on the usage status of the RU.

[0067] In the third embodiment, the system configuration and the hardware configuration of each device are similar to those in the first embodiment, so a description thereof will be omitted here.

[0068] FIG. 7 shows a flowchart of the processing flow realized when base station 110 transmits a trigger frame by having control unit 202 of base station 110 read out a program stored in memory unit 201 of base station 110 and execute it.

[0069] 7, the base station 110 receives transmission requests for data signals from the communication devices 101 and 102. Then, based on the received transmission requests, the base station 110 determines the communication devices with which it will communicate at the same time, and assigns RUs to each communication device (S701). Note that the base station 110 may determine the communication devices with which it will communicate at the same time based on the positions and radio wave environments of the communication devices 101 and 102 in addition to the transmission requests.

[0070] Next, the base station 110 determines the transmission power of each communication device based on the number of RUs used by the communication devices that communicate at the same timing (S702). For example, when two of four RUs are used and two are not used, the base station 110 determines the transmission power so that the transmission power density of each communication device is doubled. When one of four RUs is used and three are not used, the base station 110 quadruples the transmission power density of each communication device. Therefore, the transmission power in this case is four times the transmission power in S502. Note that when the transmission power cannot be quadrupled due to hardware constraints of the communication device 101 or legal constraints, the maximum transmission power that satisfies these constraints may be used.

[0071] In the above example, the transmission power of each communication device is the same, but this is not limiting and each communication device may have a different transmission power. In this case, the base station 110 determines the transmission power of each communication device so that the radio wave intensity of the entire frequency channel exceeds a predetermined threshold used by the communication device 103 during carrier sense.

[0072] For example, base station 110 acquires hardware information of each communication device and determines the transmission power of each communication device based on this information. For example, consider a case where two of four RUs are used to permit transmission to a device that can increase the transmission power density by four times and a device that cannot increase the transmission power density. In this case, base station 110 determines to triple the transmission power for the device that can increase the transmission power density by four times, and determines to reduce the transmission power density to one for the device that cannot increase the transmission power density. This satisfies the hardware requirements of each device, while at the same time, the frequency channels as a whole that communication device 103 uses during carrier sense are The signal strength may be determined to be greater than a certain threshold.

[0073] Also, for example, the base station 110 may determine each transmission power based on the reception quality of the signal from each communication device. Specifically, the base station 110 determines to increase the transmission power for devices with poor reception quality compared to devices with good reception quality. Even in this case, the base station 110 determines the transmission power for each communication device so that the radio wave intensity of the entire frequency channel exceeds a predetermined threshold used by the communication device 103 during carrier sense. Note that, as the reception quality, the signal intensity may be used, or the result of channel estimation between the base station 110 and the communication device (for example, a value obtained by calculating eigenvalues ​​of a channel matrix) may be used. In this way, the reception quality can be improved by increasing the transmission power of devices with poor reception quality, and the radio wave intensity of the entire frequency channel can exceed a predetermined threshold used by the communication device 103 during carrier sense.

[0074] Also, for example, the base station 110 may randomly determine the transmission power of each communication device while making the radio wave intensity of the entire frequency channel exceed a predetermined threshold used by the communication device 103 during carrier sense. This allows the power consumption required for data transmission by each communication device to be approximately equal when viewed as a long-term average.

[0075] Next, the base station 110 transmits a trigger frame including the transmission power of each communication device determined in S702 (S703). Note that it is possible not to give instructions regarding the transmission power to devices for which it has been determined in S702 that the transmission power should not be increased. Also, the base station 110 may notify each communication device of the transmission power of each communication device determined in S702 as a signal separate from the trigger frame.

[0076] Then, each communication device that receives the trigger frame transmits a data signal based on the transmission power instructed by the trigger frame.

[0077] This makes it possible to suppress the occurrence of errors due to interference while taking into consideration the balance with the transmission power when communication is performed using an entire frequency channel, without each communication device having to determine its own transmission power.

[0078] In the above embodiment, the following two methods are considered as a method for increasing the transmission power of a communication device. The first method is to increase the transmission power density transmitted in the RU for the communication device. The second method is to transmit signals not only in the RU for the communication device but also in other RUs. In this case, the base station 110 specifies which communication device is to use which RU. For example, the base station 110 determines a device that requests a large amount of transmission data from each device as a device that is to transmit signals in other RUs, and instructs the device to use the other RUs as well. The device then transmits data using two RUs. This increases the transmission power of the entire frequency channel and improves the data transmission efficiency.

[0079] In addition, the method to be used for increasing the transmission power of the communication device may be determined in advance, or may be switched depending on the situation. For example, even if the transmission power density is increased within the limits of hardware and laws, the second method may be used if the radio wave intensity in the entire frequency channel does not reach a predetermined threshold, and the first method may be used otherwise.

[0080] In the above embodiment, the transmission power of each communication device is determined based on the usage status of the RU. However, this is not limited to the above. Based on a transmission request from each communication device, an information processing device other than the base station may determine which communication devices the base station 110 will communicate with at the same timing, assign RUs to each communication device, and further determine the transmission power. In this case, the content of the determination is notified to the communication device via the base station 110. In this manner, the same effect can be achieved.

[0081] The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0082] 100 Wireless Network 101 Communication equipment 102 Communication equipment 103 Communication equipment 110 base station

Claims

1. An access point device that communicates with a plurality of station devices in accordance with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series standard using an OFDMA (Orthogonal Frequency Division Multiple Access) method, a transmitting means for transmitting a trigger frame including first information associating a plurality of resource units obtained by dividing a channel of a predetermined frequency bandwidth with AIDs (Association Identifiers) which are identification information of the plurality of station devices; receiving means for receiving a first signal from a first station device via a resource unit associated with an AID of a first station device among the plurality of station devices in the first information after transmitting the trigger frame; When the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a first transmission power determination method, the first station device measures a signal strength of a signal communicated between the first station device and the access point device, and transmits the first signal at a first transmission power determined in accordance with an amount by which the signal strength is less than a predetermined value; the receiving means receives the first signal transmitted by the first station device at the first transmission power; If the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a second transmission power determination method, The receiving means receives the first signal transmitted by the first station device at a predetermined second transmission power.

1. An access point device comprising:

2. The access point device described in Claim 1, characterized in that the access point device further has an antenna, and the receiving means receives a signal transmitted from the first station device using the antenna.

3. An access point device as described in claim 1 or 2, characterized in that the frequency bandwidth of the channel of the specified frequency bandwidth is 20 MHz wide.

4. An access point device as described in any one of claims 1 to 3, characterized in that the signal transmitted from the first station device received by the receiving means is a signal including a data frame.

5. The access point device according to any one of claims 1 to 4, characterized in that the access point device is a camera that performs image capture processing or a printer that performs print processing.

6. An acquisition means for acquiring information regarding the amount of data transmitted by a plurality of station devices participating in a network provided by the access point device; a determining means for determining allocation of resource units based at least on the information acquired by the acquiring means; 6. The access point device according to claim 1, further comprising:

7. The access point device described in Claim 6, characterized in that the determination means determines the allocation of resource units based at least on the acquired information so as to allocate more resource units to station devices among the plurality of station devices that transmit a larger amount of data.

8. An access point device as described in any one of claims 1 to 7, characterized in that the first station device transmits a signal in response to the trigger frame after a time corresponding to SIFS (Short Inter Frame Space) has elapsed since receiving the trigger frame.

9. An access point device as described in any one of claims 1 to 8, characterized in that the specified second transmission power is the maximum transmission power of the first station device.

10. A control method for controlling an access point device that communicates with a plurality of station devices in accordance with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series standard using an OFDMA (Orthogonal Frequency Division Multiple Access) method, comprising: a transmitting step of transmitting a trigger frame including first information associating a plurality of resource units obtained by dividing a channel of a predetermined frequency bandwidth with AIDs (Association Identifiers) that are identification information of the plurality of station devices; a receiving step of receiving a first signal from a first station device via a resource unit associated with an AID of a first station device among the plurality of station devices in the first information after transmitting the trigger frame, When the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a first transmission power determination method, the first station device measures a signal strength of a signal communicated between the first station device and the access point device, and transmits the first signal at a first transmission power determined in accordance with an amount by which the signal strength is less than a predetermined value; the receiving step includes receiving the first signal transmitted by the first station device at the first transmission power; If the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a second transmission power determination method, The receiving step includes receiving the first signal transmitted by the first station device at a predetermined second transmission power.

2. A control method for an access point device comprising:

11. A computer of a communication device capable of functioning as an access point that communicates with a plurality of station devices in accordance with the IEEE (Institute of Electrical and Electronics Engineers) 802.11 series standard using an OFDMA (Orthogonal Frequency Division Multiple Access) method, a transmitting step of transmitting a trigger frame including first information associating a plurality of resource units obtained by dividing a channel of a predetermined frequency bandwidth with AIDs (Association Identifiers) that are identification information of the plurality of station devices; a receiving step of receiving a first signal from a first station device via a resource unit associated with an AID of a first station device among the plurality of station devices in the first information after transmitting the trigger frame; A program for executing When the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a first transmission power determination method, the first station device measures a signal strength of a signal communicated between the first station device and the communication device functioning as the access point, and transmits the first signal at a first transmission power determined in accordance with an amount by which the signal strength falls short of a predetermined value; the receiving step includes receiving the first signal transmitted by the first station device at the first transmission power; If the second information related to the determination of the transmission power of the first station device acquired from the trigger frame indicates a second transmission power determination method, The receiving step includes receiving the first signal transmitted by the first station device at a predetermined second transmission power. A program characterized by:

12. The program described in Claim 11, characterized in that the frequency bandwidth of the channel of the specified frequency bandwidth is 20 MHz wide.

13. The program according to claim 11, wherein the signal transmitted from the first station device and received by the receiving step is a signal including a data frame.

14. A program described in any one of claims 11 to 13, characterized in that the program is stored in a memory unit of the communication device, and the communication device that stores the program in the memory unit is a camera that performs imaging processing or a printer that performs printing processing.

15. The program further comprises: an acquisition step of acquiring information regarding the amount of data transmitted by a plurality of station devices participating in the network provided by the communication device functioning as the access point; a determining step of determining allocation of resource units based at least on the information acquired in the acquiring step; 15. The program according to claim 11, wherein the program is executed by the computer.

16. The program described in Claim 15, characterized in that in the decision process, a decision process is executed that is based at least on the acquired information, and that determines the allocation of resource units so that more resource units are allocated to station devices among the plurality of station devices that transmit a larger amount of data.

17. A program described in any one of claims 11 to 16, characterized in that the first station device transmits a signal in response to the trigger frame after a time corresponding to SIFS (Short Inter Frame Space) has elapsed since receiving the trigger frame.

18. A program described in any one of claims 11 to 17, characterized in that the specified second transmission power is the maximum transmission power of the first station device.

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