Communication device, control method, and program

Abstract

On the basis of at least a signal strength at which a trigger frame was received, information which is included in the trigger frame and indicates transmission power, and frequency resources which are identified on the basis of information pertaining to resource allocation included in the trigger frame and which a communication device is permitted to use for uplink transmission, this communication device determines 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 and, at the determined output signal strength, transmits a trigger-based (TB) physical layer protocol data unit (PPDU) in which data is superimposed on the subcarrier corresponding to the determined tone.

Description

Communication device, control method, and program

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

[0002] In recent years, with the increase in the amount of data being communicated, the development of communication technologies such as wireless local area networks (LANs) 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] Furthermore, Patent Document 1 discloses a mechanism for performing data communication using Orthogonal Frequency Division Multiple Access (OFDMA) technology for communication in the IEEE 802.11 standard series. 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) simultaneously receives uplink data from multiple station devices (hereinafter also referred to as STA) using OFDMA technology.

[0004] JP 2018-050133 A

[0005] In the above-mentioned Uplink OFDMA function, the AP communicates simultaneously with STAs scattered in different locations and radio wave environments. Based on 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 equal to or less than the maximum transmission output power stipulated by the Radio Law of each country.

[0006] Increasing the maximum transmission power is effective for transmitting data to a distant device. 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 in Uplink OFDMA must also satisfy the transmission power density regulations stipulated by the radio wave laws of each country. Therefore, there is a problem that it is difficult for an AP to simultaneously receive data from both a STA that is far from the AP and a STA that is relatively close to the AP.

[0008] The present invention has been made in consideration of at least one of the above-mentioned problems, and an object of the present invention is 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 predetermined overall bandwidth by devising a way to use RUs.

[0009] According to one aspect of the present invention, a communication device includes: reception control means for receiving a trigger frame; determination means for determining, based at least on a signal strength of the received trigger frame, information indicating transmission power included in the trigger frame, and frequency resources that the communication device is permitted to use for uplink transmission, the frequency resources being identified based on information regarding resource allocation included in the trigger frame, a tone to be used for uplink communication from among the frequency resources and an output signal strength of a subcarrier signal for the tone; and 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. and a transmission control means for controlling the uplink communication so that a subcarrier signal (Unit) is transmitted 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 so that the transmission power density of the frequency resource as a whole is within a range of predetermined transmission power densities defined for each predetermined frequency width, and the transmission control by the transmission control means is performed so as not to transmit a subcarrier signal 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.

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

[0011] 1 is a diagram illustrating an example of the configuration of a communication system. FIG. 2 is a diagram illustrating an example of the hardware configuration of a communication device (AP / STA). FIG. 3 is a diagram illustrating an example of the functional configuration of a communication device (AP / STA). FIG. 4 is a schematic diagram illustrating an example of RU allocation in a 20 MHz channel. FIG. 5 is a schematic diagram illustrating a format of a trigger frame. FIG. 6 is a schematic diagram illustrating an example of a method of using tones in the first embodiment. FIG. 7 is a schematic diagram illustrating an example of a method of using tones in the first embodiment. FIG. 8 is a schematic diagram illustrating a comparative example of a method of using tones. FIG. 9 is a flowchart illustrating an example of control executed by a STA in the first embodiment. FIG. 10 is a schematic diagram illustrating received power at an AP. FIG. 11 is a schematic diagram illustrating received power at an AP. FIG. 12 is a schematic diagram illustrating received power at an AP.

[0012] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0013] 1 shows an example of the configuration of a network according to this embodiment. The network according to this embodiment includes one access point device (hereinafter simply referred to as an AP, AP STA, or access point) and three station devices (hereinafter simply referred to as STAs, Non-AP STAs, or stations).

[0014] The AP 100 and the STAs 101 to 103 are configured to be able to communicate wireless frames conforming to the IEEE802.11bn standard, which is the successor to the IEEE802.11be standard and targets a maximum transmission speed of 46.08 Gbps.

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

[0016] The name UHR was chosen for convenience in light of the goals and key features of the successor standard, and may be a different name once the standard is fully developed. Similarly, the name IEEE 802.11bn may be a different name once the standard is fully developed. However, it should be noted that this specification and the appended claims are essentially applicable to all successor standards to the 802.11be standard.

[0017] The AP 100 and the STAs 101-103 can communicate using frequencies in the 2.4 GHz band, 5 GHz band, 6 GHz band, and the 45 GHz band and 60 GHz band known as millimeter waves. The frequency bands used by each communication device are not limited to these, and different frequency bands, such as the Sub1 GHz band, may be used. Furthermore, the communication devices 100-103 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] Although the AP 100 and the STAs 101 to 103 are described as supporting UHR PPDU communication (transmission and reception), they can also be configured to support legacy PPDU communication, which is a standard that predates the UHR standard. Specifically, the AP 100 and the STAs 101 to 103 can be configured to support PPDU transmission and reception according to the IEEE 802.11a / b / g / n / ac / ax / be standard, etc.

[0019] The AP 100 and the STAs 101 to 103 may also be configured to support wireless communication based on other communication standards, such as Bluetooth (registered trademark), NFC, and Bluetooth (registered trademark) Low Energy (LE). NFC stands for Near Field Communication. The AP 100 and the STAs 101 to 103 may also be configured to support wired communication using an Ethernet (registered trademark) cable or wired communication using optical fiber. Specific examples of the AP 100 include, but are not limited to, a wireless LAN router and a personal computer (PC). The AP 100 and the STAs 101 to 103 may also be information processing devices, such as wireless chips that support the transmission and reception of UHR PPDUs. In this case, various controls may be performed by hardware circuits within the wireless chip. Various processes may also be performed by cooperation between a processor, memory, and hardware circuits, such as an ASIP, within the wireless chip. ASIP stands 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, wearable devices such as smart glasses, etc. The STAs 101 to 103 may also be IoT devices such as IoT sensors, smart locks, and smart sensors. The IoT sensors may be acceleration sensors, light sensors, humidity sensors, etc.

[0021] Returning to the explanation of FIG. 1, area 104 indicates an area where AP 100 and STAs 101 to 103 can communicate well. Communication between devices may be one-to-one communication, or may be MU (Multi-User) communication between AP 100 and multiple STAs. 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. Furthermore, communication devices 100 to 103 can perform MU communication using Multi-User Multi-Input Multi-Output (MU-MIMO) technology. It is also possible to perform MU communication using both OFDMA and MU-MIMO technologies.

[0023] That is, the AP 100 and multiple STAs among 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, multiple access is achieved by the AP and multiple STAs simultaneously communicating on one channel using the assigned RUs.

[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 locations and radio wave environments, as illustrated in FIG. 1. Based on this, each STA performs Power Pre-Correction control to adjust its transmission power in consideration of the spatial propagation loss between the STA and the AP. When adjusting the transmission power or controlling the transmission power when transmitting a normal PPDU, it is necessary to control the power so that it is equal to or less than the maximum transmission output power stipulated by the Radio Law of each country.

[0026] Increasing the maximum transmission power is effective for transmitting data to a distant device. As described above, in Uplink OFDMA, the communication channel used for simultaneous communication is divided into finer frequency resources and assigned to each STA, thereby realizing simultaneous communication.

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

[0028] In view of this, the present embodiment provides a mechanism for enabling an AP to receive data from a STA that is far from the AP while satisfying the maximum transmission power density requirement for the entire predetermined bandwidth by devising a way to use RUs. This will be specifically described below.

[0029] 2 shows an example of the hardware configuration of the communication device (AP 100, STAs 101 to 103). As an example of the hardware configuration, the communication device has 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 ROM and / or 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 the storage unit 201 may be a storage medium such as a non-volatile storage device, such as a hard disk or SSD (Solid State Drive), in addition to memories such as ROM and RAM.

[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 programs stored in the storage unit 201 and controls the entire device by operating hardware circuits such as the ASIC. Note that 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 also controls the functional unit 203 to perform predetermined processes such as capturing images, printing, and projection. The functional unit 203 is hardware that enables the device to perform predetermined processes. For example, if the communication device is a camera such as a digital still camera or a smartphone equipped with a camera, the functional unit 203 is an imaging unit that captures images of the surroundings via a camera unit (not shown) included in the communication device. For example, if the communication device is a printer, the functional unit 203 is a printing unit that performs printing on a sheet such as paper based on print data obtained from the outside via wireless communication. For example, if the communication device is a projector or smart glasses, the functional unit 203 is a projection unit that performs projection of image data or video data obtained from the outside via wireless communication. In the case of smart glasses, the projection surface is the end user's retina, for example. The data processed by the functional unit 203 may be data stored in the storage unit 201 or data communicated with another AP or STA via the communication unit 206 (described later). Furthermore, a communication device such as the AP 100 can also provide a network storage function such as a network attached storage (NAS). 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 the AP 100 using a protocol such as SMB, FTP, or WebDAV. The communication device such as the STA then uploads files to the storage service and downloads files from the storage. This upload and download data communication is also realized by communicating a UHR PPDU between devices.

[0033] 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, 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 implemented by a single module, such as a touch panel. The output unit 205 functions as a display means for presenting information to the user. The input unit also functions as a reception means for receiving user operations.

[0034] The communication unit 206 controls wireless communications conforming to the IEEE 802.11 standard series and IP communications. The communication unit 206 can execute communication control for transmitting and receiving UHR PPDUs, which are wireless frames conforming to the UHR standard, and PPDUs conforming 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, for example, the sub-GHz band, the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the millimeter wave band.

[0035] If the communication device is compatible with the aforementioned NFC standard, Bluetooth standard, wired communication standard, or the like, the communication unit 206 may be configured to control wireless communication or wired communication in accordance 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 controls the transmission and reception of wireless signals to and from other wireless LAN devices in cooperation with the communication unit 206 and the antenna 207. The wireless LAN control unit 301 has the function of generating and transmitting frames conforming to the IEEE 802.11 standard series, and analyzing and processing frames received via the communication unit 206. In other words, the control unit 301 has the function of controlling the 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. Settings corresponding to the setting changes made via the setting screen are 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 transmit output power, a table for deriving the number of tones to be used based on the power shortage (described later), and allocation information for specifying which tone within the sRU (described later) to allocate the tone to be used for communication. The information indicating the maximum transmit output power is an example of a predetermined threshold.

[0039] Next, the relationship between RUs and tones in OFDMA MU communication will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing the relationship between RUs and tones.

[0040] In IEEE 802.11ax / 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 this is not limited to this. An RU is a group of these tones, and the smallest resource unit in OFDMA communication is 26 tones. When allocating 26 tones, the smallest resource unit, to a 20 MHz bandwidth channel, 26 tones can be allocated to nine STAs, allowing OFDMA-style MU communication with up to nine STAs. Furthermore, when allocating the equivalent of a 20 MHz bandwidth channel to one STA for OFDMA communication, 242 tones can be allocated to one STA. While Figure 4 illustrates two sizes of RUs, the number of tones per RU can be 26, 52, 106, 242, 484, 996, 996 x 2, or the like within the communication frequency bandwidth. The AP 100 determines what size RU to allocate to which STA based on the buffer status of the STA received from the STA, and triggers uplink MU communication.

[0041] Next, an example of the transmission power density specification and the resulting maximum transmission output power will be described. As an example, the US Federal Communications Commission (FCC) certification specifies 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 refers to 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 FCC's transmission power density specification for LPI-class client devices 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 one RU has 242 tones, a transmission output of 12 dBm / 20 MHz is possible. As shown in Figure 4, if one RU has 26 tones, it is possible to allocate nine RUs within a 20 MHz band, but the upper limit of the transmission power per RU is 2 dBm / 2 MHz due to the transmission power density regulations. Therefore, one STA to which a 26-tone RU is assigned must limit its maximum transmission output power to 2 dBm / 2 MHz.

[0043] Next, the transmit power control of an STA performing OFDMA uplink MU communication will be described. OFDMA uplink MU communication is initiated when the AP 100 transmits a trigger frame that triggers the uplink communication. At this time, the STA determines the transmit output power, the RU to be used, the transmission time, etc. based on information in the trigger frame transmitted from the AP. FIG. 5 is a diagram showing an example of the format of a trigger frame transmitted by the AP 100. The fields / subfields shown here conform to the format specified in IEEE 802.11ax. That is, from the beginning, the frame 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 indicating the frame type. In this embodiment, "01" is set in the Type subfield to indicate that it is a Control frame, and "0010" is set in the Subtype subfield to indicate Trigger. In other words, this embodiment assumes that the AP 100 transmits a Basic type trigger frame. However, this is not limited to this. Any other type of trigger frame may be used as long as it assigns an RU to one or more STAs from an AP such as the AP 100 and triggers MU communication from the STA to another communication device.

[0045] The Duration field 502, RA field 503, and 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 IEEE802.11ax 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 an UL BW subfield indicating the bandwidth of uplink communication. It also includes a Spatial Reuse subfield indicating whether spatial reuse is permitted and information on the power index when spatial reuse is performed.

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

[0048] The User Info field directed to an individual STA will now be described in more detail. The AID12 subfield 510 is information identifying which STA the information is directed to. The AP 100 stores the AID (Association Identifier) ​​of the STA with which it should communicate in the AID12 subfield. Note that, when random uplink access using a corresponding RU is permitted using UORA (Uplink OFDMA Random Access) technology, 0 or 2045 is stored in this 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 STA simultaneously transmits data frames via OFDMA. The STA that receives the trigger frame identifies the RU 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 allowed to be used for uplink transmission. In other words, the RU is an example of a frequency resource to be used by the STA. 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 received signal strength expected to be received at the AP 100. The UL dRU subfield 514 is a subfield that stores information indicating whether tone allocation such as dRU is permitted. dRU will be described later. The AP 100 sets 1 to this subfield when the operation setting is configured to use the long-distance communication mode, and sets 0 to this subfield when the operation setting is configured not to use the long-distance communication mode. The information indicated in this subfield functions as information indicating whether a transmission method is permitted 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 the present embodiment sets 1 to the dRU subfield 514, it controls the Spatial Reuse subfield to store a value that prohibits Spatial Reuse. This control makes it possible to suppress spatial reuse communication in an OBSS (Overlapping Basic Service Sets) network when communication with increased power density of some tones may occur.

[0051] Upon receiving the trigger frame, the STAs 101 to 103 perform a process of determining 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 of deriving the transmission output power to be used when transmitting using that RU.

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

[0053]

[0054] Furthermore, the DL pathloss is calculated based on equation (2).

[0055]

[0056] That is, the STA calculates the DL 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, and then derives the transmission output power to be used when transmitting by adding the DL path loss to the power that the AP expects to receive.

[0057] In conventional standards such as IEEE 802.11ax / be, if the derived transmit output power is the maximum transmit output power based on radio wave regulations such as those of the FCC and exceeds the maximum transmit output power stored in the STA, transmission is performed at the maximum transmit output power. However, with this type of cutoff control, the received power at the AP may be insufficient, potentially resulting in packet errors. Based on this, when the UL dRU subfield 514 is set to 1, the STA performs tone allocation control by adjusting the transmit power by using some tones of the frequency resource and not using other tones.

[0058] A specific mechanism will be described using the schematic diagrams shown in Figures 6A and 6B. Figures 6A and 6B are schematic diagrams explaining how the average power density of the entire RU is kept within the maximum transmission output power by further subdividing the RU to increase the transmission power of subcarriers for some tones while controlling not to transmit signals in tones other than the subtones. The minimum unit of an RU up to the IEEE 802.11be standard is 26 tones. In this embodiment, however, the tones used for communication are further distributed so that some tones within the RU are used and other tones are not used. Specifically, sRUs (sub-RUs) are provided, which are further subdivided into 13 tones, and the tones used for communication are distributed within the sRUs. When one RU has 26 tones, there are two sRUs; when it has 52 tones, there are four sRUs; when it has 106 tones, there are eight sRUs; when it has 242 tones, there are eight sRUs; and when it has 996 tones, there are seventy-six sRUs.

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

[0060] 6A 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 FIGS. 6A and 6B, the transmission power of the subcarrier for one tone is determined so that it is −1 dBm / MHz when converted to an average power of 1 MHz. Specifically, the STA determines to transmit at 10.1 dBm / 1 tone.

[0061] If the STA has 26 RUs, it can allocate 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 using the entire RU for communication, it is possible to transmit at a transmission output power that is 11 dB higher. Therefore, it is possible to extend the communication range against competing devices. For example, by using this technology, STA 103 outside the area 104 where communication is possible with good results as shown in Figure 1 can perform uplink MU communication, albeit in a narrow band.

[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 regarding the maximum transmission output power within a specified frequency band. Note that since the frequency band that can be used for data transmission is narrow, the communication capacity may decrease. This relationship is explained using Table 1.

[0064] Table 1 shows the transmission power for each number of tones for which the transmission power density averaged over a predetermined bandwidth including the used and unused tones is −1 dBm / MHz. The setting storage unit 305 of the STA also 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]

[0066]

[0067] STAs 101-104 readjust their transmission power and the tones to be used, taking into account the table shown in Table 2 and the transmission power required for communication with the AP. At this time, STAs 101-104 readjust their 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, STA 101 calculates the difference between the derived power to be used for transmission and the maximum transmission output power. This difference is the amount of power that is insufficient for good communication, and will hereinafter be referred to as the power deficit. Next, STAs 101-103 use the power deficit as a primary key to search the table stored in setting storage unit 305, as shown in Table 2, and determine the number of tones to be used for communication. Next, the STAs 101 to 103 transmit trigger-based (TB) physical layer protocol data units (PPDUs) storing data in the RUs to be used by the STAs themselves to the AP 100. The TB PPDUs are assumed to be UHR TB PPDUs, but are not limited to this.

[0068] At this time, STA101-103 superimposes data onto the subcarrier signal corresponding to the tone determined to be used for communication, while controlling transmission so as not to transmit subcarrier signals for other tones. Also, at this time, STA101-103 controls transmission power so that the output signal strength of the subcarrier signal corresponding to the tone determined to be used for communication becomes the determined transmission power.

[0069] Table 2 shows the number of tones set for the aforementioned 13-tone sRU. For example, if the power shortage is 11 dB, the STA transmits using only one tone in the sRU and not using the other 12 tones. Furthermore, transmission control is performed so that the transmission output power is increased by the 11 dB power shortage. For example, if the power shortage is 1 dB, transmission is performed using 10 tones in the sRU and not using three tones. Furthermore, transmission control is performed so that the transmission output power is increased by the 1 dB power shortage.

[0070] Next, the arrangement of tones used for transmission within an sRU will be described using FIGS. 6B and 7. FIG. 7 is a schematic diagram showing a comparative example of tone arrangement. FIG. 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. If tones used for communication are arranged in adjacent areas in this way, two tones will be arranged within 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 these two tones is increased by 11 dB, the average transmission power density in the frequency bandwidth equivalent to 1 MHz shown in FIG. 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 specified 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]

[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 compensate for the power deficiency shown in Table 2. This will be explained using FIG. 6B . 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 subcarrier signals for the 12 tones between the STA and the adjacent sRU shown by the dashed line. 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 subcarrier signals for the 10 tones between the STA and the adjacent sRU shown by the dashed line. When ten 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 subcarrier signals for the 3 tones between the STA and the adjacent sRU shown by the dashed line.

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

[0075] Control of uplink communication using a dRU in an STA will be described using FIG. 8 . FIG. 8 is a flowchart showing an example of control executed in STAs such as STAs 101-103. FIG. 8 excerpts control related to OFDMA uplink MU communication performed in response to reception of a trigger frame transmitted from AP 100. Note that each process shown in the flowchart in FIG. 8 is executed by the processor of the control unit 202 of each STA such as STAs 101-103 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 working in cooperation with the various processors, ASICs, DSPs, FPGAs, etc. that constitute the communication unit 206, and the ASICs, DSPs, FPGAs, etc. that constitute the control unit 202. Note that when it is desired to clearly indicate the subject of processing, 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 wireless LAN control unit 301 determines the RU, which is the frequency resource that it 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 a User Info field storing an AID corresponding to the control unit 301 is stored in the trigger frame. If a User Info field storing an AID corresponding to the control unit 301 is stored in the trigger frame, the control unit 301 obtains the value of the RU Allocation subfield included in the trigger frame. Next, the control unit 301 identifies the 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 obtains the value 1 of the UL Target Receive Power subfield of the User Info field storing the control unit 301's AID. The control unit 301 also obtains the value 2 of the AP Tx Power subfield included in the Common Info field. The control unit 301 then substitutes the acquired value 2 and the received signal strength measured in S801 into equation (2) to derive the 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 assuming that the determined RU is used for uplink communication. While this embodiment illustrates a case of scheduled transmission in which an RU is assigned to the AID of the STA, this is not limiting. This can also be applied to a case in which the UORA function, an uplink random access technology, is used. 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, the STA determines whether it can win random access by subtracting an OBO (OFDMA backoff) counter for winning uplink contention. If it is determined that it can win, the transmission output power can be derived. In addition, if an STA has not been assigned an RU and has not won the random access contention based on the OBO counter, it decides not to participate in the MU transmission based on the trigger frame and terminates the series of processes.

[0079] In S803, the control unit 301 determines 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 determined 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 determined 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 determined 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 determines 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 determined that information permitting the use of an RU is contained, and if the value is set to 0, it is determined that information permitting the use of an RU is not contained. If the control unit 301 determines that information permitting the use of an RU is contained, it proceeds to S805. If the control unit 301 determines that information permitting the use of a dRU is not contained, it proceeds 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 this difference as a power shortage.

[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 primary 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. Subsequently, in S808, the control unit 301 sets the transmission output power taking into account the power shortage and sets the transmission conditions to transmit data with the determined tone allocation.

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

[0085] In S809, the control unit 301, in cooperation with the communication unit 206 and the antenna 207, controls the transmission of a UHR TB PPDU under the transmission conditions set in S807. When a dRU is used, the STA controls the transmission of a UHR TB PPDU, in which data is superimposed on the subcarrier of the tone determined in the above process (the tone to be used for uplink communication), at 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 subcarrier signals on 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 elapse of a Short Inter Frame Space (SIFS) time after the completion of reception of the trigger frame.

[0086] The control described above allows the tones to be used for data communication to be divided into frequency units with finer granularity than RUs, and the tones actually used for data communication to be distributed within these finer frequency units. This control makes it possible to increase the transmission output power of actual data while adhering to the regulations regarding the upper limit of average power density per 1 MHz, thereby extending the communication distance. It also makes it possible to set and transmit an MCS that achieves 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 using the comparative examples of Figures 9A to 9C and Figure 10. Figures 9A to 9C and 10 illustrate the transmission output power of each STA and the received power of the received signal at AP 100 when STAs in the positional relationship illustrated in Figure 1 perform MU communication in uplink using the OFDMA system.

[0088] Fig. 9A shows an example of reception when the transmission power is not adjusted, Fig. 9B shows an example of reception when the transmission power is adjusted without considering the upper output limit, Fig. 9C shows an example of reception when the transmission power control is performed by the conventional method, and Fig. 10 shows an example of reception when the transmission power adjustment using the dRU proposed in this embodiment is performed.

[0089] 9A shows an example in which STAs in the positional relationship illustrated 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 differs. In this case, the AP operates to reduce the gain of the receiving circuit so that the receiving circuit is not saturated by the received power of STA 102 in AP 100. Reducing the gain of the receiving circuit based on the signal transmitted from STA 102 reduces the received power of the signal transmitted from STA 103, which has the lowest received power, and reduces the received signal quality (SNR: Signal-to-Noise Ratio).

[0090] 9B shows an example of a simple case where power adjustment control based on equations (1) and (2) is 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 in that the power density regulations are not met. FIG. 9C shows an example of a conventional method in which, when the transmission power to be used for transmission exceeds the maximum transmission output power due to power adjustment control, transmission is performed at the maximum transmission power. In this example, while AP 100 can properly receive signals from STA 101 and STA 102, the received power of the signal from STA 103 is low, which may cause problems with reception quality.

[0091] Finally, FIG. 10 shows an example of the application of the method of this embodiment. The example illustrates a case where STA103, which determines that the transmission power derived based on equations (1) and (2) exceeds the maximum transmission output power, performs uplink communication using a dRU. STA103 uses the dRU to boost the transmission power used for data transmission. In this process, as described above, power adjustment and tone allocation are performed so that the average power density of a specified frequency band satisfies the output power specification. In this case, the received power of signals received from STA101 to STA103 at AP100 is uniform, thereby suppressing the aforementioned SNR degradation. This enables communication with good reception quality. Furthermore, because the SNR degradation is suppressed, STA103 can also communicate using an MCS with a higher transmission rate.

[0092] <Modification> In the first embodiment, it was assumed that the table shown in Table 2 was used when deriving the number of tones from the power shortage, but this is not limited to this. For example, it is also possible to configure multiple tables to be used depending on the magnitude of the value stored in the UL Target Receive Power subfield. The advantages of this are explained below. When the received signal strength level at the AP 100 is set relatively high, there are cases where error correction technology can cover transmission errors caused by a slight decrease in received power. In light of this, in this modification, different tables are used depending on whether the UL Target Receive Power value is -70 dBm or greater. In this case, if the UL Target Receive Power value is less than -70 dBm, the number of tones is derived using the table shown in Table 2, and if the value is -70 dBm or greater, the number of tones shown in Table 4 is set. In this case, if the power shortage is less than 5 dBm, the mSTA may perform data communication using all 13 tones.

[0093]

[0094] Furthermore, although the present embodiment illustrates a case in which data is superimposed on each tone determined to be used for uplink communication, the present invention is not limited to this. Some of the tones determined to be used for uplink communication can also be used as pilot signals on which no data is superimposed. In this case, although the data transmission capacity is reduced, the number of pilot signals that serve as reception references can be increased, thereby improving reception quality at the AP.

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

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

[0097] (Configuration 2) The communication device according to Configuration 1, wherein the trigger frame includes information indicating an AID (Association Identifier) ​​of the communication device, and information corresponding to the AID, 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, wherein the trigger frame further includes, as information corresponding to the AID, information indicating whether 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 communication device according to Configuration 2 or 3, wherein the trigger frame includes, as information corresponding to the AID, information indicating a received signal strength that is expected to be received at the communication device that is the sender of the trigger frame, and the determination means determines the tone to be used and the output signal strength of a subcarrier signal in that tone based on the signal strength at which the trigger frame was received, information indicating transmission power included in the trigger frame, and information indicating the signal strength that is expected to be received at the communication device that is the sender.

[0100] (Configuration 5) The communication device according to Configuration 4, further comprising a second determination means for determining a transmission output power on the assumption that all subcarriers corresponding to the frequency resource are used for uplink communication, based on the signal strength of the received trigger frame, information indicating the transmission power included in the trigger frame, and information indicating the signal strength expected to be received at the source communication device, wherein 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 to be tones smaller than 26 tones.

[0101] (Configuration 6) The communication device according to Configuration 5, wherein, when the determining means determines that fewer than 26 tones should be used for the uplink communication, the fewer than 26 tones are allocated within the frequency resources based on allocation information stored in the communication device.

[0102] (Configuration 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 determining 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 control method for 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 frequency resources and an output signal strength of a subcarrier signal in the tone, based at least on a signal strength of the trigger frame received by the communication device, information indicating 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 step of controlling transmission of a Trigger-based Physical Layer Protocol Data Unit (TB) having data superimposed on a subcarrier corresponding to the tone to be used determined in the determination step, at the output signal strength determined in the determination step, wherein in the determination step, the tone to be used for the uplink communication and the transmission output power are determined so that the transmission power density of the frequency resource as a whole falls within a range of a predetermined transmission power density defined for each predetermined frequency width, a transmission control step of controlling transmission so as not to transmit subcarrier signals on 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] The present invention can also be realized by a process in which a program that realizes 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., an ASIC) that realizes one or more of the functions.

[0107] The invention is not limited to the above-described embodiments, and various changes and modifications can be made 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.

[0108] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0109] This application claims priority based on Japanese Patent Application No. 2023-125726, filed August 1, 2023, the entire contents of which are incorporated herein by reference.

[0110] 100 AP 101 STA 102 STA 103 STA 206 Communication 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 for the tone, based at least on a signal strength of the received trigger frame, information indicating 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; 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 so that the transmission power density of the entire frequency resource is 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. The communication device according to claim 1, characterized in that the trigger frame includes information indicating an AID (Association Identifier) ​​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 communications device according to claim 2, characterized in that the trigger frame includes information corresponding to the AID, which indicates a received signal strength expected to be received at the communications device that transmitted the trigger frame, and the determination means determines the tone to be used and the output signal strength of the subcarrier signal for that tone based on the signal strength at which the trigger frame was received, information indicating the transmission power included in the trigger frame, and information indicating the signal strength expected to be received at the communications device that transmitted the trigger frame.

5. The communication device according to claim 4, further comprising a second determination means for determining a transmission output power on the assumption that all of the subcarriers corresponding to the frequency resource are used for uplink communication, based on the signal strength of the received trigger frame, information indicating the transmission power contained in the trigger frame, and information indicating the signal strength expected to be received at the source communication device, wherein 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 to be tones smaller than 26 tones.

6. The communication device according to claim 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.

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

8. The communication device according to any one of claims 1 to 7, characterized in that the communication device is an IoT (Internet of Things) device.

9. A control method for 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 of the signal received by the communication device when the trigger frame is received, information indicating transmission power contained 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 contained in the trigger frame; and a transmission control step of 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 to be used determined in the determination step, at the output signal strength determined in the determination step, wherein in the determination step, the tone to be used for the uplink communication and the transmission output power are determined so that the 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 communication device control method according to claim 9.

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