Communication device, control method, and program

Abstract

To provide a device which enables an AP to receive data from an STA separated from the AP while satisfying the regulation of maximum transmission power density.SOLUTION: At least based on a signal intensity at which a trigger frame is received, information indicating transmission power included in the trigger frame and frequency resources which are identified based on information relating to a resource allocation included in the trigger frame, allowing a communication device to use the frequency resources for uplink transmission, the communication device: determines a tone to be used for uplink communication from among the frequency resources and an output signal intensity of a subcarrier signal in the tone; and transmits a Trigger-based (TB) Physical layer Protocol Data Unit (PPDU) in which data is superposed on a subcarrier corresponding to the determined tone, at the determined output signal intensity.SELECTED DRAWING: Figure 10

Description

[Technical field]

[0001] The present invention relates to a communication device for communicating data. [Background technology]

[0002] In recent years, with the increase in the amount of data being communicated, the development of communication technologies such as wireless LANs (Local Area Networks) has been progressing. The IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known as the main communication standard for wireless LANs. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax.

[0003] Patent Document 1 also discloses a mechanism for performing data communication using OFDMA (Orthogonal frequency-division multiple access) technology in IEEE802.11 standard series communication. Specifically, it discloses a mechanism (hereinafter also referred to as Uplink OFDMA function) in which an access point device (hereinafter also referred to as AP) uses OFDMA technology to simultaneously receive uplink data from multiple station devices (hereinafter also referred to as STAs). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-050133 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Uplink OFDMA function, the AP communicates simultaneously with STAs that are located in different positions and in different radio wave environments. In consideration of this, the STA performs power pre-correction control to adjust the transmission power in consideration of the spatial propagation loss between the AP and the STA. When adjusting the transmission power or controlling the transmission power when transmitting a normal PPDU, it is necessary to perform power control so that the transmission output power is below the maximum transmission output power stipulated by the Radio Law of each country.

[0006] By the way, in order to transmit data to a distant device, it is effective to increase the maximum transmission power. In the above-mentioned Uplink OFDMA, the communication channel used for simultaneous communication is divided into finer frequency resources and assigned to each STA to achieve simultaneous communication. This division unit is called RU (Resource Unit).

[0007] The maximum transmission output power of each STA using Uplink OFDMA must also satisfy the transmission power density regulations stipulated by the Radio Law of each country. Therefore, there is a problem that it is difficult for an AP to simultaneously receive data from both STAs that are far from the AP and STAs that are relatively close to the AP.

[0008] The present invention has been made in consideration of at least one of the above problems. One aspect of the present invention aims to provide a mechanism that enables an AP to receive data from a STA that is far from the AP while satisfying the maximum transmission power density requirement for a given bandwidth as a whole, by devising a way of using RUs. [Means for solving the problem]

[0009] According to one aspect of the present invention, a communication device includes a reception control means for receiving a trigger frame, a determination means for determining a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal in the tone based at least on a signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and a frequency resource that the communication device is allowed to use for uplink transmission, the frequency resource being specified based on information on resource allocation included in the trigger frame, and a transmission control means for controlling transmission of a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is superimposed on a subcarrier corresponding to the tone determined by the determination means, at the output signal strength determined by the determination means, wherein the determination means determines the tone to be used for the uplink communication and the transmission output power such that a transmission power density of the frequency resource as a whole is within a range of a predetermined transmission power density defined for each predetermined frequency width, and the transmission control by the transmission control means is performed such that a subcarrier signal is not transmitted in other tones constituting the frequency resource that are different from the tone to be used for the uplink communication determined by the determination means. Effect of the Invention

[0010] According to one aspect of the present invention, it is possible to receive data from a STA far from an AP while satisfying the maximum transmission power density regulation, thereby expanding the communication range in which the STA can communicate with the AP. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates an example of a configuration of a communication system. [Diagram 2] A diagram illustrating an example of the hardware configuration of a communication device (AP / STA). [Diagram 3] A diagram illustrating an example of the functional configuration of a communication device (AP / STA). [Figure 4]FIG. 1 is a schematic diagram showing an example of RU allocation in a 20 MHz channel. [Diagram 5] FIG. 2 is a schematic diagram illustrating the format of a trigger frame. [Figure 6] FIG. 4 is a schematic diagram showing an example of a method of using tones in the first embodiment. [Figure 7] FIG. 13 is a schematic diagram showing a comparative example of a method of using tones. [Figure 8] 6 is a flowchart showing an example of control executed by a STA according to the first embodiment. [Figure 9] FIG. 11 is a schematic diagram for explaining the received power at an AP. [Figure 10] FIG. 11 is a schematic diagram for explaining the received power at an AP. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a plurality of features, not all of these features are essential to the invention, and the plurality of features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0013] <First embodiment> An example of the configuration of a network according to this embodiment is shown in Fig. 1. The network according to this embodiment includes one access point device (hereinafter, also simply referred to as AP, AP STA, or access point) and three station devices (hereinafter, also simply referred to as STA, Non-AP STA, or stations).

[0014] The AP 100 and the STAs 101 to 103 are configured to be capable of communicating wireless frames that comply with the IEEE802.11bn standard, which is the successor to the IEEE802.11be standard and has a target maximum transmission speed of 46.08 Gbps.

[0015] IEEE is an abbreviation for the Institute of Electrical and Electronics Engineers. The successor standard to IEEE802.11be, IEEE802.11bn, has high reliability and low latency communication, and improved throughput during congestion as its main features. Another goal of 802.11bn is to reduce power consumption in APs. Wireless frames communicated under this successor standard are also called UHR (Ultra High Reliability) PPDU. PPDU is an abbreviation for Physical layer Protocol Data Unit.

[0016] The name UHR is a name given for convenience in consideration of the goals and features of the successor standard, and may be a different name when the standard is completed. Similarly, the name IEEE802.11bn may be a different name when the standard is completed. However, it should be noted that this specification and the appended claims are essentially applicable to all successor standards that are successors to the 802.11be standard.

[0017] The AP 100 and the STAs 101 to 103 can communicate at frequencies of the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the 45 GHz band and the 60 GHz band called millimeter waves. The frequency bands used by each communication device are not limited to these, and a different frequency band such as the Sub 1 GHz band may be used. In addition, the communication devices 100 to 103 can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 540 MHz, 640 MHz, 1080 MHz, and 2160 MHz. The bandwidths used by each communication device are not limited to these.

[0018] In addition, the AP 100 and the STAs 101 to 103 can be configured to support communication (transmission and reception) of UHR PPDUs, but can also be configured to support communication of PPDUs of legacy standards that predate the UHR standard. Specifically, the AP 100 and the STAs 101 to 103 can be configured to support transmission and reception of PPDUs of the IEEE802.11a / b / g / n / ac / ax / be standards, etc.

[0019] The AP100 and the STAs 101 to 103 can also be configured to support wireless communication based on other communication standards such as Bluetooth (registered trademark), NFC, and Bluetooth (registered trademark) LE (Low Energy). NFC is an abbreviation for Near Field Communication. The AP100 and the STAs 101 to 103 can also be configured to support wired communication using an Ethernet (registered trademark) cable or wired communication using optical fiber. Specific examples of the AP100 include, but are not limited to, a wireless LAN router and a personal computer (PC). The AP100 and the STAs 101 to 103 may also be information processing devices such as wireless chips that support the transmission and reception of UHR PPDU. In this case, the AP100 and the STAs 101 to 103 can be configured to execute various controls using hardware circuits inside the wireless chip. The AP100 and the STAs 101 to 103 can also be configured to execute various processes by cooperation between a processor, memory, and hardware circuits such as an ASIP inside the wireless chip. ASIP is an abbreviation for Application-specific instruction set processor.

[0020] Specific examples of the STAs 101 to 103 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, and wearable devices such as smart glasses. The STAs may also be IoT devices such as IoT (Internet of Things) sensors, smart locks, and smart sensors. The IoT sensors may be acceleration sensors, light sensors, humidity sensors, and the like.

[0021] Returning to the description of Fig. 1, an area 104 indicates an area where the AP 100 and the STAs 101 to 103 can communicate satisfactorily. The communication between the devices may be one-to-one communication, or may be MU (Multi-User) communication between the AP 100 and multiple STAs. The simultaneous communication related to this embodiment will be described in more detail below.

[0022] 1 can perform MU communication using Orthogonal Frequency Division Multiple Access (OFDMA) technology. Also, communication devices 100 to 103 can perform MU communication using Multi-User Multi-Input Multi-Output (MU-MIMO) technology. Note that it is also possible to perform MU communication using both OFDMA technology and MU-MIMO technology.

[0023] That is, the AP 100 and multiple STAs among the STAs 101 to 103 can communicate simultaneously on one channel (including a combined channel with a channel width of 40 MHz or more). In OFDMA technology, one channel is divided into multiple subchannels called Resource Units (RUs), and each RU is assigned to a different STA (or a group of STAs consisting of multiple STAs). Then, the AP and multiple STAs communicate simultaneously on one channel using the assigned RUs, thereby achieving multiple access.

[0024] Hereinafter, in this embodiment, the AP 100 receiving uplink data from multiple STAs simultaneously is referred to as an Uplink OFDMA function.

[0025] In the above-mentioned Uplink OFDMA function, the AP 100 communicates simultaneously with STAs scattered in different positions and radio wave environments as shown in Fig. 1. In consideration of this, each STA performs power pre-correction control to adjust the transmission power in consideration of the spatial propagation loss between the AP and the STA. When adjusting the transmission power or controlling the transmission power when transmitting a normal PPDU, it is necessary to perform power control so that the transmission output power is equal to or less than the maximum transmission output power stipulated by the Radio Law of each country.

[0026] In order to transmit data to a distant device, it is effective to increase the maximum transmission power. As mentioned above, in Uplink OFDMA, the communication channel used for simultaneous communication is divided into finer frequency resources and assigned to each STA to achieve simultaneous communication.

[0027] In this case, the maximum transmission output power of each STA is capped by the transmission power density stipulated in each country's radio law, which can make it difficult for the AP to simultaneously receive data from both STAs that are far away from the AP and STAs that are relatively close to the AP.

[0028] In view of this, in this embodiment, a mechanism is provided that enables an AP to receive data from a STA that is far from the AP while satisfying the maximum transmission power density requirement for a given bandwidth as a whole by devising a way of using RUs. This will be described in detail below.

[0029] <Hardware configuration of communication device> 2 shows an example of a hardware configuration of a communication device (AP 100, STAs 101 to 103). The communication device includes, as an example of the hardware configuration, a storage unit 201, a control unit 202, a function unit 203, an input unit 204, an output unit 205, a communication unit 206, and antennas 207 to 209.

[0030] The storage unit 201 is configured with both or either one of a ROM and a RAM, and stores various information such as programs for performing various operations described below and communication parameters for wireless communication. RAM stands for Random Access Memory, and ROM stands for Read Only Memory. Note that, as the storage unit 201, in addition to memories such as ROM and RAM, storage media such as non-volatile storage devices such as hard disks and SSDs (Solid State Drives) may be used.

[0031] The control unit 202 is configured with, for example, a processor such as a CPU or MPU, an ASIC (Application Specific Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), etc. Here, CPU stands for Central Processing Unit, and MPU stands for Micro Processing Unit. The control unit 202 executes the programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as the ASIC. The control unit 202 may control the entire device in cooperation with the programs stored in the storage unit 201 and an OS (Operating System).

[0032] The control unit 202 controls the functional unit 203 to perform predetermined processing such as imaging, printing, and projection. The functional unit 203 is hardware for the device to perform predetermined processing. For example, when the communication device is a camera such as a digital still camera or a smartphone having a camera, the functional unit 203 is an imaging unit that performs imaging processing of surrounding images via a camera unit (not shown) of the communication device. For example, when the communication device is a printer, the functional unit 203 is a printing unit that performs printing processing on a sheet such as paper based on print data obtained from the outside through wireless communication. For example, when the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection processing of image data or video data obtained from the outside through wireless communication. In the case of smart glasses, the projection surface is the retina of an end user. The data processed by the functional unit 203 may be data stored in the storage unit 201, or may be data communicated with other APs or STAs via the communication unit 206 described later. Furthermore, a communication device such as the AP 100 can provide a network storage function such as a NAS (Network Attached Storage). This function is provided to other communication devices as a Web service such as a network storage service. For example, a communication device such as an STA connects to a network storage service provided by an AP 100 or the like using a protocol such as SMB, FTP, or WebDAV. The communication device such as an STA then uploads files to the storage service and downloads files from the storage. The data communication for uploading and downloading is also realized by communicating UHR PPDU between devices.

[0033] The input unit 204 receives various operations from the user. The output unit 205 performs various outputs to the user. Here, the output by the output unit 205 includes, for example, at least one of display on a screen, audio output by a speaker, and vibration output. Note that both the input unit 204 and the output unit 205 may be realized by one module, such as a touch panel. The output unit 205 functions as a display unit that presents information to the user. The input unit also functions as a receiving unit that receives user operations.

[0034] The communication unit 206 controls wireless communication conforming to the IEEE802.11 standard series and IP communication. The communication unit 206 can execute communication control for transmitting and receiving UHR PPDU, which is a wireless frame of the UHR standard, and PPDU corresponding to earlier standards in cooperation with the antenna 207. The antenna 207 is an antenna capable of transmitting and receiving signals in at least one of the frequency bands of the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the millimeter wave band, for example.

[0035] When the communication device is compatible with the above-mentioned NFC standard, Bluetooth standard, wired communication standard, or the like, the communication unit 206 may be configured to control wireless communication or wired communication that complies with these communication standards.

[0036] Next, the functional configuration of the AP 100 and the STAs 101 to 103 will be described with reference to Fig. 3. Each of the communication devices such as the AP 100 and the STAs 101 to 103 includes a wireless LAN control unit 301, a UI control unit 304, and a setting storage unit 305.

[0037] The wireless LAN control unit 301 cooperates with the communication unit 206 and the antenna 207 to control transmission and reception of wireless signals with other wireless LAN devices. The wireless LAN control unit 301 has a function of generating and transmitting frames conforming to the IEEE802.11 standard series, and analyzing and processing frames received via the communication unit 206. That is, the control unit 301 has a function of controlling reception and transmission of frames.

[0038] The UI control unit 304 controls the input unit 204 and the output unit 205 to present information to the user and accept input operations from the user. The UI control unit 304 of the AP 100 displays a setting screen (not shown) and accepts an operation to change the operation settings regarding whether or not to use the long-distance communication mode. The setting corresponding to the setting change made via the setting screen is stored in the setting storage unit 305. The setting storage unit 305 stores the operation settings regarding whether or not to use the long-distance communication mode and various setting parameters for communication. The setting storage unit 305 also stores information indicating the maximum transmission output power, a table for deriving the number of tones to be used based on the power shortage described later, and arrangement information for identifying which tone in the sRU to use for communication is to be arranged. The information indicating the maximum transmission output power is an example of a predetermined threshold.

[0039] Next, the relationship between RUs and tones in OFDMA MU communications will be explained using Fig. 4. Fig. 4 is a schematic diagram showing the relationship between RUs and tones.

[0040] In IEEE802.11ax / be / bn, subcarriers in OFDMA communication are called tones. In this embodiment, the frequency bandwidth of one tone is assumed to be 78.125 kHz, but is not limited to this. An RU is a collection of these tones in a continuous manner, and the smallest resource unit in OFDMA communication is 26 tones. When allocating 26 tones, which is the smallest resource unit, in a channel with a bandwidth of 20 MHz, 26-tone resources can be allocated to nine STAs, and OFDMA-type MU communication can be performed with a maximum of nine STAs. In addition, when a channel equivalent to a bandwidth of 20 MHz is allocated to one STA for OFDMA communication, 242-tone resources can be allocated to one STA. Although two sizes of RUs are illustrated in FIG. 4, the number of tones per RU can be 26, 52, 106, 242, 484, 996, 996×2 tones, etc. within the communication frequency bandwidth. The AP 100 determines which size of RU should be allocated to which STA based on the buffer status of the STA received from the STA, and triggers uplink MU communication.

[0041] Next, the specification of transmission power density and the maximum transmission output power according to it will be described with an example. As an example, in the FCC (Federal Communications Commission) certification in the United States, it is specified that the transmission power density in the 6 GHz band should be -1 dBm / MHz for client devices with a transmitter output of 250 mW or less. More specifically, a client device with a transmitter output of 250 mW or less indicates an LPI (Low Power Indoor) client device. -1 dBm is an example of a predetermined transmission power density, and 1 MHz is an example of a predetermined frequency bandwidth. Hereinafter, in this embodiment, the specification of the transmission power density of an LPI class client device of the FCC will be described as an example of a transmission power density specification.

[0042] This means that if the communication frequency bandwidth is 20 MHz and 1 RU has 242 tones, a transmission output of 12 dBm / 20 MHz is possible. As shown in Figure 4, if 1 RU has 26 tones, it is possible to place 9 RUs within a 20 MHz band, but the upper limit of the transmission power per 1 RU is 2 dBm / 2 MHz due to the transmission power density regulations. Therefore, a single STA to which a 26-tone RU is assigned must limit its maximum transmission output power to 2 dBm / 2 MHz.

[0043] Next, the transmission power control of the STA performing the OFDMA uplink MU communication will be described. The OFDMA uplink MU communication is started when the AP 100 transmits a trigger frame that triggers the uplink communication. At this time, the STA determines the transmission output power, the RU to be used by itself, the transmission time, etc. based on the information in the trigger frame transmitted from the AP. FIG. 5 is a diagram showing an example of the format of the trigger frame transmitted by the AP 100. The fields / subfields shown here conform to the format specified in IEEE802.11ax. That is, from the beginning, it includes a Frame Control field 501, a Duration field 502, an RA field 503, a TA field 504, a Common Info field 505, a User Info List field 506, a Padding field 507, and an FCS field 508.

[0044] The Frame Control field 501 includes a Type subfield and a Subtype subfield that indicate the frame type. In this embodiment, the Type subfield is set to "01" indicating that it is a Control frame, and the Subtype subfield is set to "0010" indicating a Trigger. In other words, in this embodiment, it is assumed that the AP 100 transmits a Basic type trigger frame. However, this is not limited to this. It is sufficient that an AP such as the AP 100 assigns an RU to one or more STAs and causes the STA to perform MU communication with another communication device, and other types of trigger frames may also be used.

[0045] The Duration field 502, the RA field 503, and the TA field 504 conform to the contents of the MAC (Media Access Control) header of a trigger frame, which is a control frame defined in the IEEE 802.11ax standard.

[0046] The Common Info field 505 is a field in which common information and communication parameters for STAs participating in MU communication are stored, and includes an AP Tx Power subfield 509. This subfield includes the transmission signal strength when the AP 100 transmits the trigger frame shown in Fig. 5. It also includes an UP Link Length subfield indicating the duration of uplink communication, and a UL BW subfield indicating the bandwidth of uplink communication. It further includes a Spatial Reuse subfield indicating whether spatial reuse is permitted and information on the power index when spatial reuse is performed.

[0047] Next, User Info List field 506 is a field in which one or more User Info fields in which communication parameters for each STA participating in MU communication are stored. AP 100 includes in List field 506 a User Info field for the number of STAs participating in MU communication.

[0048] The User Info field directed to individual STAs will now be described in further detail. The AID12 subfield 510 is information for identifying which STA the information is directed to. The AP 100 stores the AID (Association Identifier) ​​of the STA with which communication should be performed in the AID12 subfield. When random uplink access using the corresponding RU is permitted using UORA (Uplink OFDMA Random Access) technology, 0 or 2045 is stored in the subfield. On the other hand, when the AP 100 assigns an RU to an individual STA, the AID issued by the AP 100 to the STA when the STA associates with the AP 100 is stored.

[0049] The following RU Allocation subfield 511 stores information indicating the allocation of RUs to be used when the STAs simultaneously transmit data frames by OFDMA. The STA that receives the trigger frame identifies the RUs to be used by itself based on the value of the RU Allocation subfield assigned to its own AID and the value of the UL BW subfield of the Common Info field. Identifying the RU means identifying a frequency resource that is permitted to be used for uplink transmission. In other words, the RU is an example of a frequency resource that the STA should use. The value of the RU Allocation subfield and the value of the UL BW subfield of the Common Info field are examples of information regarding resource allocation.

[0050] The UL HE-MCS subfield 512 stores the MCS (Modulation and Coding Scheme) to be used by the STA identified by the AID. The UL Target Receive Power subfield stores information indicating the strength of the received signal expected to be received by the AP 100. The UL dRU subfield 514 stores information indicating whether tone allocation such as dRU is permitted. The dRU will be described later. When the AP 100 is configured to operate in a long-distance communication mode, the AP 100 sets the subfield to 1, and when the AP 100 is configured to operate in a long-distance communication mode, the AP 100 sets the subfield to 0. The information indicated in this subfield functions as information indicating whether or not to permit a transmission method in which transmission power is adjusted by using some tones of the RU (frequency resource) allocated to the STA and not using other tones. In addition, when the AP 100 of this embodiment sets the dRU subfield 514 to 1, the AP 100 controls the Spatial Reuse subfield to store a value that prohibits Spatial Reuse. This control makes it possible to suppress spatial reuse communications in an OBSS (Overlapping Basic Service Sets) network when communications with increased power density of some tones may occur.

[0051] The STAs 101 to 103 that have received the trigger frame perform a process to determine whether there is an RU that they are permitted to use. If the STAs 101 to 103 determine that there is an RU that they are permitted to use, they perform a process to derive the transmission output power to be used when transmitting using that RU.

[0052] The derivation is based on equation (1).

[0053]

number

[0054] In addition, DL pathloss is calculated based on equation (2).

[0055]

number

[0056] That is, the STA calculates DL pathloss, which is a spatial path loss, based on the transmission power of the trigger frame included in the trigger frame and the received power when the trigger frame is actually received.Then, the STA derives the transmission output power to be used when transmitting by adding the DL pathloss to the power that the AP expects to receive.

[0057] In conventional standards such as IEEE802.11ax / be, if the derived transmission output power is the maximum transmission output power based on radio wave regulations such as FCC and exceeds the maximum transmission output power stored in the STA, it is specified that transmission is performed at the maximum transmission output power. However, with such a cut-off control, the reception power at the AP may become insufficient, and packet errors may occur. In light of this, when 1 is set in the UL dRU subfield 514, the STA adjusts the transmission power by using some tones of the frequency resource and not using other tones, thereby performing tone allocation control.

[0058] A specific mechanism will be described using the schematic diagram illustrated in FIG. 6. FIG. 6 is a schematic diagram for explaining how the average power density of the RU as a whole is kept within the maximum transmission output power by further dividing the RU to increase the transmission power of subcarriers of some tones while controlling not to transmit signals with tones other than the some tones. The minimum unit of the RU up to the IEEE802.11be standard is 26 tones, but in this embodiment, the tones used for communication are distributed so that some tones in the RU are used and other tones are not used. Specifically, sRUs (sub-RUs) further divided into 13 tones are provided, and the tones used for communication are distributed within the sRU. When 1 RU has 26 tones, there are 2 sRUs, when 1 RU has 52 tones, there are 4 sRUs, when 1 RU has 106 tones, there are 8 sRUs, when 1 RU has 242 tones, there are 18 sRUs, and when 1 RU has 996 tones, there are 76 sRUs.

[0059] The frequency bandwidth of one tone assumed in this embodiment is 78.125 kHz, and the bandwidth of a 13-tone sRU in this case is 1.015625 MHz. Therefore, if the maximum transmission power density is specified as -1 dBm / MHz, when all 13 tones of the sRU are used for transmission, -1 dBm / MHz becomes the maximum transmission output power allowed.

[0060] Fig. 6(a) illustrates a case where only one tone in an sRU is used for communication, and the other 12 tones are not used for communication. In this embodiment, as shown in Fig. 6, the transmission power of the subcarrier of one tone is determined so that it is -1 dBm / MHz when converted into an average power of 1 MHz. Specifically, the STA determines to transmit at 10.1 dBm / 1 tone.

[0061] If the STA has 26 tones assigned to its RU, the STA can assign one tone to each sRU, enabling it to transmit two tones. In this case, the maximum transmission output power of one tone can be set to 10.1 dBm, as described above.

[0062] In this case, compared to the conventional maximum transmission output power of 2 dBm / 2 MHz when the entire RU is used for communication, it is possible to transmit at a transmission output power 11 dB higher. Therefore, it is possible to expand the communication range with respect to the opposing device. For example, STA 103 outside the area 104 where communication can be performed well as shown in FIG. 1 can perform uplink MU communication, albeit in a narrow band, by using this technology to communicate.

[0063] In this way, by increasing the transmission power of some tones and not using other tones, it is possible to expand the communication range while satisfying the regulations on the maximum transmission output power in a specified frequency band. Note that the frequency band that can be used for data transmission is narrow, so the communication capacity available may decrease. This relationship is explained using Table 1.

[0064] Table 1 shows the transmission power for each number of tones that results in a transmission power density of -1 dBm / MHz averaged over a given bandwidth including tones that are used and tones that are not used. The setting storage unit 305 of the STA stores the table shown in Table 2 as a table for deriving the number of tones to be used based on the power shortage.

[0065] [Table 1]

[0066] [Table 2]

[0067] The STAs 101 to 104 readjust the transmission power and the tones to be used, taking into consideration the table shown in Table 2 and the transmission power required for communication with the AP. At this time, the STAs 101 to 104 readjust the transmission power and the tones to be used so that the largest number of tones is selected within the range of transmission power that allows good communication with the AP. Specifically, when the power to be used for transmission derived using Equation 1 exceeds its own maximum transmission output power, the STAs 101 obtains a difference value between the derived power to be used for transmission and the maximum transmission output power. The difference value is the amount of power that is insufficient for good communication, and is hereinafter also referred to as insufficient power. Next, the STAs 101 to 103 use the insufficient power as a primary key to search the table stored in the setting storage unit 305 shown in Table 2, and determine the number of tones to be used for communication. Next, the STAs 101 to 103 transmit to the AP 100 a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is stored in the RU to be used by the STAs 101 to 103. The TB PPDU is assumed to be, but is not limited to, a UHR TB PPDU.

[0068] At this time, the STAs 101 to 103 superimpose data onto the subcarrier signals corresponding to the tones determined to be used for communication, while controlling transmission so as not to transmit subcarrier signals for the other tones. Also, at this time, the STAs 101 to 103 control transmission power so that the output signal strength of the subcarrier signals corresponding to the tones determined to be used for communication becomes the determined transmission power.

[0069] Table 2 shows the number of tones set for the 13-tone sRU mentioned above. For example, if the power shortage is 11 dB, the STA performs transmission using only one tone in the sRU and not using the other 12 tones. In addition, the transmission output power at this time is controlled so that the transmission power is increased by the 11 dB power shortage. For example, if the power shortage is 1 dB, the STA performs transmission using 10 tones in the sRU and not using 3 tones. In addition, the transmission output power at this time is controlled so that the transmission power is increased by the 1 dB power shortage.

[0070] Next, the arrangement of tones used for transmission within an sRU will be explained using Figures 6(b) and 7. Figure 7 is a schematic diagram showing a comparative example of tone arrangement. Figure 7 shows an example in which a tone at the end of sRU1 and a tone at the end of sRU2 adjacent to that end are used for transmission. In this way, if tones used for communication are arranged in adjacent areas, two tones will be arranged in a band equivalent to 1 MHz. If tones are arranged in this way and transmission power control is performed so that the transmission power of the two tones is increased by 11 dB, the average transmission power density in the frequency bandwidth equivalent to 1 MHz shown in Figure 7 will exceed the specified value of -1 dBm / MHz.

[0071] In view of this, in this embodiment, the arrangement of the tones to be used is set according to the number of tones to be used so that transmission can be performed within the regulations of the transmission power density. Table 3 shows the number of tones to be used. Table 3 is an example of arrangement information for specifying the arrangement of the tones.

[0072] [Table 3]

[0073] Based on the arrangement information shown in Table 3, each STA arranges the tones to be used consecutively from the left end of the sRU and controls the transmission power to make up for the power deficiency shown in Table 2. This will be explained using FIG. 6(b). When one tone is used, the STA uses the subcarrier signal of the one tone at the left end for data communication, while controlling not to transmit the subcarrier signal for the 12 tones between the adjacent sRUs shown by the dashed lines. When two tones are used, the STA uses the subcarrier signal of the two tones at the left end for data communication, while controlling not to transmit the subcarrier signal for the 10 tones between the adjacent sRUs shown by the dashed lines. When 10 tones are used, the STA uses the subcarrier signal of the 10 tones at the left end for data communication, while controlling not to transmit the subcarrier signal for the 3 tones between the adjacent sRUs shown by the dashed lines.

[0074] In this manner, in this embodiment, the tones used for communication are arranged in consideration of the presence of tones used for data communication in adjacent sRUs. By adopting this arrangement method, even if an average power density of an arbitrary 1 MHz band is measured in an RU used for communication by one STA, the average power density of the arbitrary 1 MHz band can be prevented from exceeding a specified value. In this manner, an allocation in which tones to be used for communication are arranged at intervals in an RU so that the average power density of the 1 MHz band is equal to or less than a specified value is called a dRU (distributed RU). In addition, uplink communication using the dRU is also called uplink communication using a dRU. Note that the method of arranging tones used for communication from the left end is one example, and the arrangement method is not limited to this.

[0075] The control of uplink communication using dRU in the STA will be described with reference to FIG. 8. FIG. 8 is a flowchart showing an example of control executed in the STAs such as STAs 101 to 103. FIG. 8 is an excerpt of control related to OFDMA uplink MU communication performed in response to reception of a trigger frame transmitted from the AP 100. Note that each process shown in the flowchart of FIG. 8 is executed by a processor of the control unit 202 of the STAs such as STAs 101 to 103 executing a computer program stored in the storage unit 201. Note that some processes such as transmission and modulation are realized by the processor of the control unit 202, various processors, ASICs, DSPs, and FPGAs constituting the communication unit 206, and ASICs, DSPs, and FPGAs constituting the control unit 202 in cooperation with each other. Note that when it is desired to clearly indicate the subject of the process, the functional units described in FIG. 3 will be used as the subject.

[0076] In S801, the wireless LAN control unit 301 cooperates with the antenna 207 and the communication unit 206 to receive a trigger frame transmitted by the AP 100 and measure the received signal strength of the trigger frame.

[0077] Next, in S802, the WLAN control unit 301 determines an RU that is a frequency resource that the WLAN control unit 301 should use based on the trigger frame, and derives the transmission output power assuming that the determined RU is used for uplink communication.

[0078] Specifically, the control unit 301 analyzes the AID12 subfield of the User Info List field of the trigger frame, and determines whether or not a User Info field in which an AID corresponding to the control unit 301 is stored is stored in the trigger frame. If a User Info field in which an AID corresponding to the control unit 301 is stored is stored in the trigger frame, the control unit 301 acquires a value of the RU Allocation subfield included in the trigger frame. Then, the control unit 301 identifies an RU to be used by the control unit 301 based on the value of the RU Allocation subfield and the value of the UL BW subfield included in the Common Info field. Next, the control unit 301 acquires value 1 of the UL Target Receive Power subfield of the User Info field in which the control unit 301's AID is stored. Also, the control unit 301 acquires value 2 of the AP Tx Power subfield included in the Common Info field. Then, the control unit 301 substitutes the acquired value 2 and the received signal strength measured in S801 into equation (2) to derive DL pathloss. Next, the control unit 301 substitutes the derived DL pathloss and the acquired value 1 into equation (1) to derive the transmission output power when it is assumed that the determined RU is used for uplink communication. In this embodiment, the case of scheduled transmission in which an RU is assigned to the AID of the STA is illustrated, but the present invention is not limited to this. It can also be applied to the case of using the UORA function, which is an uplink random access technology. In this case, the STA identifies the number of random RUs in which 0 or 2045 is stored in the AID12 subfield. Next, based on the identified number of RUs, it determines whether or not it can win random access by subtracting an OBO (OFDMA backoff) counter for winning uplink contention. If it is determined that it can win, it is sufficient to derive the transmission output power. Note that a STA that is not assigned an RU for itself and that has not won the random access contention based on the OBO counter determines that it will not participate in the MU transmission based on the trigger frame, and ends the series of processes.

[0079] In S803, the control unit 301 judges whether the transmission output power derived in S802 is equal to or less than the value (predetermined threshold) indicating the maximum transmission output power stored in the setting storage unit 305. If it is judged that the transmission output power derived in S802 is equal to or less than the value indicating the maximum transmission output power, the process proceeds to S808. On the other hand, if it is judged that the transmission output power derived in S802 is not equal to or less than the value indicating the maximum transmission output power (i.e., if it is judged that the transmission output power exceeds the value indicating the maximum transmission output power), the process proceeds to S804.

[0080] In S804, the control unit 301 judges whether the User Info field corresponding to its own AID contains information permitting the use of a dRU. Specifically, the control unit 301 acquires the value of the UL dRU subfield 514 of the received trigger frame. If the value is set to 1, it is judged that the information permitting the use of an RU is contained, and if the value is set to 0, it is judged that the information permitting the use of an RU is not contained. If the control unit 301 judges that the information permitting the use of an RU is contained, it advances the process to S805, and if it judges that the information permitting the use of a dRU is not contained, it advances the process to S808.

[0081] In S805, the control unit 301 derives the difference between the maximum transmission output power stored in the setting storage unit 305 and the transmission output power derived in S802, and stores the difference as a power deficit.

[0082] Subsequently, in S806, the control unit 301 searches the table (the table exemplified in Table 2) stored in the setting storage unit 305 using the power shortage as a main key, and determines the number of tones to be used for communication.

[0083] In S807, the control unit 301 determines the tone allocation of the dRU based on the number of tones determined in S806 and the allocation information exemplified in Table 3. Next, in S808, the control unit 301 sets the transmission conditions to transmit data with the determined tone allocation and with the transmission output power that takes into account the power shortage.

[0084] If the control unit 301 judges Yes in S803, it sets the transmission condition to transmit data using the transmission output power derived in S802 and the entire RU determined in S802. If the control unit 301 judges No in S804, it sets the transmission condition to transmit data using the maximum transmission power and the entire RU determined in S802.

[0085] In S809, the control unit 301 cooperates with the communication unit 206 and the antenna 207 to control the transmission of the UHR TB PPDU under the transmission conditions set in S807. When using a dRU, the STA controls the transmission of the UHR TB PPDU, in which data is superimposed on the subcarrier of the tone (tone to be used for uplink communication) determined in the above process, with the determined output signal strength. The UHR TB PPDU is transmitted to the AP, which is the communication device that transmitted the trigger frame. At this time, the STA controls the transmission so as not to transmit a subcarrier signal in other tones in the RU that are different from the tone to be used for the uplink communication. The control unit 301 transmits the UHR TB PPDU in response to the lapse of a Short Inter Frame Space (SIFS) time from the completion of reception of the trigger frame.

[0086] With the above-described control, the tones to be used for data communication can be divided into frequency units with finer granularity than RU, and the tones actually used for data communication can be distributed within the finer frequency units. This control makes it possible to increase the transmission output power of actual data while observing the regulations regarding the upper limit of the average power density per 1 MHz, and to extend the communication distance. It also makes it possible to set and transmit an MCS that realizes a high transmission rate while extending the communication distance.

[0087] Finally, the effect of performing the series of controls described in this embodiment will be described with reference to a comparative example in Fig. 9 and Fig. 10. Figs. 9 and 10 show examples of the transmission output power of each STA and the received power of the received signal at AP 100 when the STAs in the positional relationship illustrated in Fig. 1 perform uplink MU communication using the OFDMA system.

[0088] Fig. 9(a) shows an example of reception when the transmission power is not adjusted, Fig. 9(b) shows an example of reception when the transmission power is adjusted without considering the upper output limit, and Fig. 9(c) shows an example of reception when the transmission power control of the conventional method is performed. Also, Fig. 10 shows an example of reception when the transmission power adjustment using the dRU proposed in this embodiment is performed.

[0089] Fig. 9(a) shows an example of a case where STAs in the positional relationship shown in Fig. 1 transmit data using a common transmission output power. Signals emitted by each STA are transmitted to the AP via transmission paths with different propagation environments. Therefore, the received power of the signals received from each STA at the AP is different. In this case, the gain of the receiving circuit is lowered so that the receiving circuit of the AP 100 is not saturated by the received power of STA 102. Lowering the gain of the receiving circuit based on the signal transmitted from STA 102 causes a decrease in the received power of the signal transmitted from STA 103, which has the minimum received power, and a decrease in the received signal quality (SNR: Signal Noise Ratio).

[0090] FIG. 9(b) shows an example of a case where power adjustment control based on formulas (1) and (2) is simply performed. By performing such adjustment, the received power of signals received from each STA at the AP can be made uniform. However, there is a problem that the power density regulation is not satisfied. FIG. 9(c) shows an example of a conventional method of transmitting at the maximum transmission power when the transmission power to be used for transmission exceeds the maximum transmission output power due to power adjustment control. In this example, although the AP 100 can properly receive signals from STA 101 and STA 102, the received power of the signal from STA 103 becomes low, which may cause a problem in reception quality.

[0091] Finally, FIG. 10 shows an example of the case where the method of this embodiment is applied. The example shows a case where STA103, which has determined that the transmission power derived based on formulas (1) and (2) exceeds the maximum transmission output power, performs uplink communication using dRU. STA103 performs a process of boosting the transmission power used for data transmission by using dRU. In this process, as described above, power adjustment and tone arrangement are performed so that the average power density of a predetermined frequency band satisfies the output power regulation. In this case, the received power of the signals received from STA101 to STA103 in AP100 becomes uniform, so that the above-mentioned decrease in SNR is also suppressed. Therefore, it is possible to perform communication with good reception quality. In addition, since the decrease in SNR is suppressed, it is possible for STA103 to communicate using an MCS with a higher transmission rate.

[0092] <Modification> In the first embodiment, the table shown in Table 2 is assumed to be used when deriving the number of tones from the power shortage, but the present invention is not limited to this. For example, it is also possible to configure to use a plurality of tables depending on the magnitude of the value stored in the UL Target Receive Power subfield. The advantages of this will be described. When the received signal strength level in the AP 100 is set relatively high, there are cases where the transmission error caused by a slight decrease in the received power can be covered by error correction technology. In view of this, in the modified example, the table to be used is changed depending on whether the value of the UL Target Receive Power is -70 dBm or more. In this case, if the value is not -70 dBm or more, the number of tones is derived using the table shown in Table 2 described above, and if the value is -70 dBm or more, the number of tones is set as shown in Table 4. In this case, if the power shortage is less than 5 dBm, the mSTA may perform data communication using all 13 tones.

[0093] [Table 4]

[0094] In addition, in the present embodiment, the case where data is superimposed on each tone determined to be used for uplink communication is illustrated, but the present invention is not limited to this. A part of each tone determined to be used for uplink communication can be a pilot signal on which data is not superimposed. In this case, although the data transmission capacity is reduced, the number of pilot signals serving as a reference for reception can be increased, thereby improving the reception quality at the AP.

[0095] (Other embodiment 1) The disclosure of this embodiment also includes the following configuration.

[0096] (Configuration 1) 1. A communication device, comprising: A reception control means for receiving a trigger frame; a determination means for determining a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal in the tone, based at least on a signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and a frequency resource that is permitted to be used for uplink transmission by the communication device, the frequency resource being specified based on information regarding resource allocation included in the trigger frame; a transmission control means for controlling transmission of a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is superimposed on a subcarrier corresponding to the tone determined by the determining means, at an output signal strength determined by the determining means; the determining means determines a tone to be used for the uplink communication and a transmission output power such that a transmission power density of the entire frequency resource falls within a range of a predetermined transmission power density defined for each predetermined frequency width; A communication device characterized in that, in the transmission control by the transmission control means, transmission control is performed so as not to transmit subcarrier signals in other tones constituting the frequency resource that are different from the tones to be used for the uplink communication determined by the determination means.

[0097] (Configuration 2) The communication device described in configuration 1, characterized in that the trigger frame includes information indicating an AID (Association Identifier) ​​of the communication device and, as information corresponding to the AID, information indicating the frequency resources that the communication device identified by the AID is allowed to use for uplink transmission.

[0098] (Configuration 3) The communication device according to configuration 2, characterized in that the trigger frame further includes, as information corresponding to the AID, information indicating whether or not a transmission method is permitted in which transmission power is adjusted by using some tones of the frequency resource and not using other tones.

[0099] (Configuration 4) The trigger frame includes, as information corresponding to the AID, information indicating a received signal strength expected to be received at a communication device that is a transmission source of the trigger frame, The communication device according to configuration 2 or 3, wherein the determination means determines the tone to be used and the output signal strength of a subcarrier signal in the tone, based on the signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and information indicating a signal strength expected to be received at the source communication device.

[0100] (Configuration 5) and a second determination means for determining a transmission output power in a case where all subcarriers corresponding to the frequency resource are used for uplink communication, based on a signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and information indicating a signal strength expected to be received at the source communication device, The communication device according to configuration 4, characterized in that, when the frequency resource is 26 tones and the transmission output power determined by the second determination means exceeds a predetermined threshold, the determination means determines that the tones to be used for the uplink communication are tones smaller than 26 tones.

[0101] (Configuration 6) The communication device according to configuration 5, characterized in that, when the determination means determines that the tones to be used for the uplink communication are tones less than 26 tones, the tones less than 26 tones are arranged within the frequency resources based on information specifying the arrangement stored in the communication device.

[0102] (Configuration 7) 7. The communication device according to any one of configurations 1 to 6, wherein the minimum number of tones to be used in the uplink communication determined by the determination means is two tones.

[0103] (Configuration 8) The communication device according to any one of configurations 1 to 7, wherein the communication device is an IoT (Internet of Things) device.

[0104] (Configuration 9) A method for controlling a communication device, comprising: a reception control step of receiving a trigger frame; a determination step of determining a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal in the tone, based at least on a signal strength at which the communication device receives the trigger frame, information indicating a transmission power included in the trigger frame, and a frequency resource that is permitted to be used for uplink transmission by the communication device, the frequency resource being specified based on information on resource allocation included in the trigger frame; a transmission control step of controlling a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is superimposed on a subcarrier corresponding to the tone to be used determined in the determination step, so as to be transmitted at the output signal strength determined in the determination step; In the determining step, a tone to be used in the uplink communication and a transmission output power are determined so that a transmission power density of the entire frequency resource falls within a range of a predetermined transmission power density defined for each predetermined frequency width; A control method characterized in that, in the transmission control step, transmission control is performed so as not to transmit subcarrier signals in other tones within the frequency resource that are different from the tones to be used for the uplink communication determined in the determination step.

[0105] (Configuration 10) A program for causing a computer to execute the communication device control method according to configuration 9.

[0106] (Other embodiment 2) 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.

[0107] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0108] 100 AP 101STA 102 STA 103 STA 206 Communications Department

Claims

1. A communication device, comprising: A reception control means for receiving a trigger frame; a determination means for determining a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal in the tone, based at least on a signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and a frequency resource that is permitted to be used for uplink transmission by the communication device, the frequency resource being specified based on information regarding resource allocation included in the trigger frame; and a transmission control means for controlling transmission of a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is superimposed on a subcarrier corresponding to the tone determined by the determining means, at an output signal strength determined by the determining means; the determining means determines a tone to be used for the uplink communication and a transmission output power such that a transmission power density of the entire frequency resource falls within a range of a predetermined transmission power density defined for each predetermined frequency width; A communication device characterized in that, in the transmission control by the transmission control means, transmission control is performed so as not to transmit subcarrier signals in other tones constituting the frequency resource that are different from the tones to be used for the uplink communication determined by the determination means.

2. 2. The communication device according to claim 1, wherein the trigger frame includes information indicating an association identifier (AID) of the communication device, and information corresponding to the AID, indicating the frequency resources that the communication device identified by the AID is permitted to use for uplink transmission.

3. The communication device according to claim 2, characterized in that the trigger frame further includes, as information corresponding to the AID, information indicating whether or not a transmission method is permitted in which transmission power is adjusted by using some tones of the frequency resource and not using other tones.

4. the trigger frame includes, as information corresponding to the AID, information indicating a received signal strength expected to be received at a communication device that is a transmission source of the trigger frame; 3. The communication device according to claim 2, wherein the determination means determines the tone to be used and the output signal strength of a subcarrier signal in the tone based on a signal strength of the received trigger frame, information indicating a transmission power contained in the trigger frame, and information indicating a signal strength expected to be received at the source communication device.

5. a second determination means for determining a transmission output power in a case where all subcarriers corresponding to the frequency resource are used for uplink communication, based on a signal strength of the received trigger frame, information indicating a transmission power included in the trigger frame, and information indicating a signal strength expected to be received at the source communication device; 5. The communication device according to claim 4, characterized in that, when the frequency resource is 26 tones and the transmission output power determined by the second determination means exceeds a predetermined threshold, the determination means determines that the tones to be used for the uplink communication are tones less than 26 tones.

6. 6. The communication device according to claim 5, wherein when the determination means determines that the tones to be used for the uplink communication are less than 26 tones, the tones less than 26 tones are arranged within the frequency resources based on information specifying the arrangement stored in the communication device.

7. 2. The communication device according to claim 1, wherein the minimum number of tones to be used in the uplink communication determined by the determining means is two tones.

8. The communication device according to claim 1 , wherein the communication device is an IoT (Internet of Things) device.

9. A method for controlling a communication device, comprising: a reception control step of receiving a trigger frame; a determination step of determining a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal in the tone, based at least on a signal strength at which the communication device receives the trigger frame, information indicating a transmission power included in the trigger frame, and a frequency resource that is permitted to be used for uplink transmission by the communication device, the frequency resource being specified based on information on resource allocation included in the trigger frame; a transmission control step of controlling a TB (Trigger-based) PPDU (Physical layer Protocol Data Unit) in which data is superimposed on a subcarrier corresponding to the tone to be used determined in the determination step, so as to be transmitted at the output signal strength determined in the determination step; In the determining step, a tone to be used in the uplink communication and a transmission output power are determined so that a transmission power density of the entire frequency resource falls within a range of a predetermined transmission power density defined for each predetermined frequency width; A control method characterized in that, in the transmission control step, transmission control is performed so as not to transmit subcarrier signals in other tones within the frequency resource that are different from the tones to be used for the uplink communication determined in the determination step.

10. A program for causing a computer to execute the method for controlling a communication device according to claim 9.

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