Communication devices, communication methods, and programs

Abstract

This technology provides a way to appropriately apply Distributed Tone Resource Units (DRUs) to Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) in a Basic Service Set (BSS). [Solution] A communication device according to one aspect of the present disclosure includes a transmission means that transmits a frame requesting the other AP to perform data transmission using Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) with a Distributed Tone Resource Unit (DRU) from a communication device belonging to a Basic Service Set (BSS) managed by the other AP.

Description

Technical Field

[0001] The present disclosure relates to a communication device, a communication method, and a program.

Background Art

[0002] In recent years, with the increase in the amount of data to be communicated, the development of communication technologies such as wireless local area networks (LANs) has been progressing. As the main communication standards for wireless LANs, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard series is known. The IEEE 802.11 standard series includes IEEE 802.11a / b / g / n / ac / ax / be standards, etc. For further improvement of communication reliability, the development of the IEEE 802.11bn standard is underway as a successor standard to the IEEE 802.11be standard. In the IEEE 802.11 Working Group (WG) that formulates the IEEE 802.11bn standard, the goals and scope of study of this standard are determined in the Ultra High Reliability (UHR) Study Group (SG). Also, in the IEEE 802.11 WG, the detailed technical content to be included in this standard is planned to be defined in Task Group bn (TGbn).

[0003] The IEEE 802.11 standard series employs Orthogonal Frequency Division Multiple Access (OFDMA) to improve throughput and frequency utilization efficiency. In OFDMA, the frequency channel used between communication devices is divided along the frequency axis to form multiple units. Each unit is called a Resource Unit (RU). By assigning each RU to a station, an Access Point (AP) enables parallel communication between the AP and multiple stations. This improves the overall frequency utilization efficiency of the communication system. Hereafter, a station will also be referred to as a non-AP Station, non-AP STA, or simply STA.

[0004] Meanwhile, in recent years, many countries have been developing legal regulations to allow wireless LANs to use the 6GHz frequency band. Using the 6GHz band will further improve wireless LAN throughput. However, the legally permitted transmit power density for the 6GHz band is smaller than that for the 2.4GHz and 5GHz bands, which have traditionally been used in wireless LANs. Therefore, in the development of the IEEE 802.11bn standard, technologies are being considered to increase transmit power while maintaining legally permitted transmit power density when using the 6GHz band. For example, an OFDMA scheme is being considered that uses a Distributed Tone Resource Unit (DRU) to allocate wireless resources, which consists of RUs composed of multiple subcarriers arranged so that at least some of the subcarriers are discontinuous on the frequency axis. Such RUs can be called Distributed Tone Resource Units (DRUs).

[0005] Furthermore, the IEEE 802.11bn standard is considering the introduction of a multiple access method called Coordinated OFDMA (C-OFDMA). C-OFDMA is a technology in which STAs belonging to different Basic Service Sets (BSSs) share frequency channels using the OFDMA method. This can improve frequency utilization efficiency compared to when STAs belonging to a single BSS share frequency channels using the OFDMA method.

[0006] Furthermore, Non-Patent Document 1 also considers applying DRU to C-OFDMA. This would allow for increased transmission power while maintaining compliance with legally regulated limits for transmission power density, in addition to improving frequency utilization efficiency with C-OFDMA. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Brian Hart et al., “Discussion on Distributed RUs (DRUs) (IEEE802.11-24 / 0332r0)”, IEEE802.11, 2024. [Overview of the project] [Problems that the invention aims to solve]

[0008] However, if the AP managing each of the multiple BSSs, or the STA connected to the AP, is unaware that C-OFDMA using DRU is applied to data transmission, the performance or quality of communication may deteriorate, for example, due to inability to synchronize data transmission timing. Therefore, it may not be possible to properly apply DRU to C-OFDMA in a BSS.

[0009] One aspect of this disclosure, in view of the above, aims to provide a technology for appropriately applying DRU to C-OFDMA in BSS. [Means for solving the problem]

[0010] A communication device according to one aspect of the present disclosure is a communication device that functions as an Access Point (AP) as defined in the IEEE 802.11 standard series, and includes a transmission means for transmitting a frame requesting the other AP to perform data transmission using Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) with a Distributed Tone Resource Unit (DRU) from a communication device belonging to a Basic Service Set (BSS) managed by the other AP. [Effects of the Invention]

[0011] According to one aspect of this disclosure, by sending a frame requesting that data be transmitted using C-OFDMA with DRU, an AP or an STA connected to the AP can know that C-OFDMA with DRU is applied to the data transmission. Therefore, DRU can be appropriately applied to C-OFDMA in the BSS. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example configuration of a wireless communication system according to the embodiment. [Figure 2] This figure shows an example of the hardware configuration of a communication device according to the embodiment. [Figure 3] This figure shows an example of the functional configuration of a communication device according to the embodiment. [Figure 4] This figure shows an example of frame exchange between communication devices according to an embodiment. [Figure 5] This figure shows an example of frames exchanged during the C-OFDMA request phase according to the embodiment. [Figure 6] This figure shows an example of frames exchanged in the C-OFDMA data exchange phase according to the embodiment. [Figure 7] This figure shows another example of frames exchanged in the C-OFDMA data exchange phase according to the embodiment. [Figure 8] It is a flowchart showing an operation example of an AP related to the exchange of information indicating the ability to support C-OFDMA / DRU between APs according to an embodiment. [Figure 9] It is a flowchart showing an operation example of an AP in a C-OFDMA request phase according to an embodiment. [Figure 10] It is a flowchart showing an operation example of an AP in a C-OFDMA data exchange phase according to an embodiment. [Figure 11] It is a flowchart showing an operation example of a STA according to an embodiment. [Figure 12] It is a diagram showing an example of a RU arrangement pattern when arranging RUs of each RU type on the frequency axis in a PPDU composed of OFDM symbols with a bandwidth of 80 MHz. [Figure 13] It is a diagram showing an example of the relationship between RU type, RU index, and subcarrier index. [Figure 14] It is a diagram showing the concept of C-OFDMA using DRU. [Figure 15] It is a diagram showing a configuration example of a UHR Capabilities element. [Figure 16] It is a diagram showing a configuration example of a Trigger frame.

Mode for Carrying Out the Invention

[0013] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the content described in the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

[0014] (Embodiment) FIG. 1 is a diagram showing a configuration example of a wireless communication system according to this embodiment.

[0015] The wireless communication system shown in Figure 1 includes two wireless local area networks (LANs), namely wireless LAN 100 and wireless LAN 120. These wireless LANs are Basic Service Sets (BSS) as defined in the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard series. Hereafter, wireless LAN 100 will also be referred to as BSS100, and wireless LAN 120 will also be referred to as BSS120.

[0016] BSS100 includes communication devices 101 to 103. Communication device 101 is an Access Point (AP) as defined in the IEEE 802.11 standard series. Communication devices 102 and 103 are non-Access Point Stations (non-AP STA) as defined in the IEEE 802.11 standard series. Hereafter, communication devices 101, 102, and 103 will also be referred to as AP101, STA102, and STA103, respectively.

[0017] BSS120 includes communication devices 121 to 123. Communication device 121 is an AP as defined in the IEEE 802.11 standard series. Communication devices 122 and 123 are non-AP STAs as defined in the IEEE 802.11 standard series. Hereafter, communication devices 121, 122, and 123 will also be referred to as AP121, STA122, and STA123, respectively.

[0018] AP101 and AP121 may be connected via a wired LAN through a wired LAN hub 150. AP101 and AP121 connected via a wired LAN may support Ethernet®, and the wired LAN may be Ethernet.

[0019] Hereafter, when it is not necessary to distinguish between communication devices 101-103 and communication devices 121-123, they will simply be referred to as "communication devices." When it is not necessary to distinguish between AP101 and AP121, they will simply be referred to as "AP." When it is not necessary to distinguish between STA102, STA103, STA122, and STA123, they will simply be referred to as "STA."

[0020] The communication device is configured to perform communication methods compliant with the successor standard to the IEEE 802.11be standard.

[0021] For example, a communication device can be configured to perform a communication method compliant with the IEEE 802.11bn standard. The main features of the IEEE 802.11bn standard include functions that realize highly reliable communication, low latency communication, improved throughput when the wireless communication medium is congested, and reduced power consumption at the access point (AP). The IEEE 802.11bn standard can also be called the Ultra High Reliability (UHR) standard. A communication device can also perform a communication method compliant with a successor standard to the IEEE 802.11bn standard. Wireless frames used in communication between communication devices compliant with a successor standard to the IEEE 802.11be standard are sometimes called UHR Physical Layer Protocol Data Units (PPDUs).

[0022] The designation UHR was adopted for convenience, taking into account the goals this standard aims to achieve and the distinctive features defined within it. In other words, this standard may be given a different name once its development is complete. Similarly, the designation IEEE 802.11bn may also be given a different name once its development is complete. It should be noted that, including these cases, this specification and the attached claims are essentially applicable to all successor standards to the IEEE 802.11be standard.

[0023] Furthermore, the communication device may support at least one of the legacy standards that predate the IEEE 802.11bn standard. In other words, the communication device can communicate using legacy standard PPDUs. Legacy standards include, for example, the IEEE 802.11a / b / g / n / ac / ax / be standards.

[0024] Furthermore, the communication device may support other communication standards such as Bluetooth®, Near Field Communication (NFC), Ultra Wide Band (UWB), ZigBee®, and MBOA. MBOA is an abbreviation for Multi Band OFDM Alliance. UWB includes Wireless USB, Wireless 1394, WiNET, etc.

[0025] Furthermore, the communication device may support communication standards such as wired LAN.

[0026] An AP (Access Point) is, for example, a wireless LAN router or a personal computer (PC), but is not limited to these.

[0027] STA can be, but is not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, smart glasses, and other wearable devices. STA may also be IoT devices such as Internet of Things (IoT) sensors, smart locks, and smart sensors. IoT sensors may include acceleration sensors, light sensors, humidity sensors, and the like.

[0028] These APs and STAs may be information processing devices such as wireless chips that comply with the IEEE 802.11bn standard and are capable of transmitting and receiving UHR PPDU. In this case, the hardware circuitry inside the wireless chip can be configured to perform various controls. Furthermore, the wireless chip can be configured to perform various processes through the cooperation of a processor such as an Application-Specific Instruction Set Processor (ASIP), memory, and hardware circuitry inside the wireless chip.

[0029] Communication devices can communicate using radio signals in frequency bands such as the 2.4GHz, 3.6GHz, 5GHz, 6GHz bands, and millimeter wave bands such as the 45GHz and 60GHz bands. The frequency bands used by communication devices are not limited to these, and may include, for example, the sub-1GHz band. Furthermore, communication devices can communicate using frequency channels with bandwidths of 20MHz, 40MHz, 80MHz, 160MHz, 320MHz, 540MHz, 640MHz, 1080MHz, and 2160MHz. The bandwidths used by communication devices are not limited to these, and may include, for example, 240MHz or 4MHz. Note that a 40MHz frequency channel can be formed by combining two 20MHz frequency channels. Similarly, an 80MHz frequency channel can be formed by combining two 40MHz frequency channels. An 80MHz frequency channel may also be formed by combining four 20MHz frequency channels. Similarly, frequency channels such as 160MHz and 320MHz can be formed by combining or linking multiple frequency bands narrower than their respective bandwidths.

[0030] The IEEE 802.11 standard series specifies a function that increases throughput by enabling multi-user (MU) communication, where an access point (AP) multiplexes wireless resources to communicate simultaneously with multiple stas (STAs). For example, an AP can communicate in parallel with multiple STAs using Orthogonal Frequency Division Multiple Access (OFDMA). In OFDMA, the data field of a PPDU transmitted using a frequency channel of a predetermined bandwidth is divided into multiple units on the frequency axis. The predetermined bandwidth can be 20MHz, 40MHz, 80MHz, 160MHz, 320MHz, etc. Each of these units is called a Resource Unit (RU). Each RU can be assigned to a different STA. Each AP and one or more STAs can communicate in parallel using the RUs assigned to their respective STAs. This enables multi-user communication. Note that one RU may be assigned to a group of STAs composed of multiple STAs.

[0031] Furthermore, an AP can communicate with multiple STAs in parallel using MU Multiple-Input And Multiple-Output (MIMO) communication. In this case, the AP has multiple antennas and transmits different signals from each antenna using the same frequency channel. Each STA simultaneously receives the signals transmitted from each antenna, separates each signal, and decodes each signal. In MIMO communication, the propagation paths used for communication between the AP and each STA are spatially orthogonal. By utilizing this spatial orthogonality, the AP can communicate with multiple STAs in parallel within a defined bandwidth. In this way, by performing multi-user communication, the AP can communicate more data with each STA in the same amount of time compared to not performing multi-user communication. OFDMA and multi-user MIMO can be used together.

[0032] The data fields contained within a PPDU consist of one or more Orthogonal Frequency Division Multiplexing (OFDM) symbols. Each OFDM symbol consists of multiple subcarriers, also known as tones or subcarriers. For example, one OFDM symbol with an 80 MHz bandwidth may consist of 1024 subcarriers. In this case, each subcarrier may be spaced 78.125 kHz apart.

[0033] In OFDMA, a single RU (Router Unit) is formed by multiple grouped subcarriers. Multiple types of RUs can be formed based on the number of subcarriers that make up the RU. For example, possible types of RUs include 26-tone RU, 52-tone RU, 106-tone RU, 242-tone RU, 484-tone RU, and 996-tone RU. The number of subcarriers that make up each type of RU can be 26, 52, 106, 242, 484, 996, etc. Thus, the number of subcarriers that make up the RU can be indicated by the RU type. The number of subcarriers that make up an RU is sometimes called the RU size.

[0034] Figure 12 shows an example of RU placement patterns when each RU type is placed on the frequency axis in a PPDU composed of OFDM symbols with a bandwidth of 80 MHz. In the following explanation, a PPDU composed of OFDM symbols with a predetermined bandwidth may be simply referred to as a PPDU with a predetermined bandwidth.

[0035] In Figure 12, the horizontal axis represents frequency. For example, in the case of a 26-tone RU, 37 RUs can be placed on the frequency axis. In the case of a 52-tone RU, 106-tone RU, 242-tone RU, 484-tone RU, and 996-tone RU, 16, 8, 4, 2, and 1 RU can be placed, respectively. Thus, different RU types result in different numbers of subcarriers constituting a single RU and different numbers of RUs that can be placed in a PPDU of the same bandwidth. In a single PPDU, each RU can be identified by its RU type and RU index. For example, in the case of a 26-tone RU type with an 80MHz bandwidth, each RU can be assigned one of RU indices from 1 to 37. For example, the RU index can indicate the position of each RU on the frequency axis. Note that multiple RUs of different RU types can be placed on the frequency axis. For example, RU index 1 and 2 of a 26-tone RU, RU index 2 of a 52-tone RU, and RU index 2 of a 106-tone RU can all constitute a single PPDU.

[0036] Furthermore, each subcarrier included in the OFDM symbol that constitutes the PPDU can be identified by a subcarrier index. For an 80MHz bandwidth, for example, each of the 1024 subcarriers may be assigned a subcarrier index of one of the integers in the range of -512 to 511.

[0037] Figure 13 shows an example of the relationship between RU type, RU index, and subcarrier index. For example, the subcarrier index for the center frequency subcarrier on the frequency axis within the frequency band occupied by one OFDM symbol is set to 0, and subcarriers with lower frequencies are assigned negative index values, with the absolute value increasing as the frequency decreases. On the other hand, subcarriers with frequencies higher than the center frequency are assigned positive index values, with the absolute value increasing as the frequency increases. Note that the absolute value of the difference in indices between adjacent subcarriers can be 1.

[0038] Figure 13 shows an example where a small RU index is formed by subcarriers with small subcarrier index values, and a large RU index is formed by subcarriers with large subcarrier index values. In this way, when a specific RU is specified by the RU type and RU index, the index of the subcarriers that make up that specific RU is determined. For example, the subcarrier index that makes up RU1 of a 26-tone RU ranges from -449 to -474. This means that, for example, if an AP specifies the RU type and RU index, the STA can identify the subcarrier index from the specified RU type and RU index and communicate using that subcarrier.

[0039] The subcarriers may include data subcarriers used for data transmission, pilot subcarriers used for pilot signal transmission, and unused subcarriers not used for any transmission. Unused subcarriers may include DC subcarriers, which are the DC component (DC: Direct Current) and its neighboring subcarriers, guard band subcarriers at the edge of the frequency band occupied by the PPDU, and null subcarriers that are none of these subcarriers. For example, as shown in Figure 13, the indices of the subcarriers constituting RU19 of the 26-tone RU are from -16 to -4 and from 4 to 16. This RU is positioned across the DC subcarrier. For example, a null subcarrier may be positioned between adjacent RUs.

[0040] Furthermore, the bandwidth of PPDUs communicated between communication devices is not limited to 80 MHz. For example, PPDUs with bandwidths of 20 MHz, 40 MHz, 160 MHz, 320 MHz, etc., can be communicated. In these cases, subcarriers and RUs may be arranged on the frequency axis according to their respective bandwidths.

[0041] Furthermore, the RU type, RU index, and subcarrier index applicable to each bandwidth can be predetermined, similar to the case for the 80 MHz bandwidth. For example, even if the PPDU bandwidth is different, the number of subcarriers constituting each RU may be the same. That is, even if the PPDU bandwidth is different, the RU type used may be the same. In this case, the range of the subcarrier index assigned to each subcarrier may differ due to the different PPDU bandwidths. Also, the range of the RU index assigned to each RU may differ. As a result, the correspondence between the RU index and the subcarrier index may differ from the correspondence shown in Figure 13. In this case, for example, the specifications for the RU type, RU index, and subcarrier index corresponding to each PPDU bandwidth in the IEEE 802.11 standard series can be used. For example, in the case of a PPDU with a bandwidth wider than 80 MHz, the arrangement of RUs may be such that the RUs in an 80 MHz bandwidth PPDU are repeated multiple times on the frequency axis, as defined in the IEEE 802.11ax and IEEE 802.11be standards. In this case, the term DC subcarrier refers not to the actual DC component of the PPDU and the subcarriers in its vicinity, but to the subcarriers located at the center and in the vicinity of each 80 MHz band that constitutes a PPDU with a bandwidth wider than 80 MHz. Furthermore, in addition to the RU type and RU index, the RUs may be identified by information indicating where the 80 MHz bandwidths repeated multiple times on the frequency axis are located within the total bandwidth of the PPDU.

[0042] As described above, when the RU used in OFDMA is composed of continuous subcarriers on the frequency axis, this RU may be called a Regular RU (RRU). Alternatively, this RU may be called a continuous RU, etc. An RRU may include multiple data subcarriers and / or pilot subcarriers that are continuous on the frequency axis. Furthermore, as in RU19 of the 26-tone RU shown in Figure 13, the subcarriers constituting the RU may be separated by a DC subcarrier, and the RU may be composed of two groups of continuous subcarriers on the frequency axis. Such an RU is also considered to be composed of subcarriers that are essentially continuous on the frequency axis and is called an RRU. An RRU can also be described as an RU in which there are no subcarriers constituting other RUs between the subcarriers constituting the RRU.

[0043] In OFDMA using RRU, the transmit power density can generally be high. Transmit power density is the transmit power per unit frequency. That is, in OFDMA using RRU, continuous subcarriers are used on the frequency axis, so the transmit power is concentrated in a given bandwidth, which can result in a high transmit power density. On the other hand, transmit power density is subject to legal regulations set by each country, so it is not possible to transmit at power exceeding that limit. For example, the transmit power density limit is set low in the 6GHz band, so when communicating using OFDMA with RRU in the 6GHz band, the transmit power of each subcarrier may be low. This may make it difficult for the signal to reach STAs that are far from the AP.

[0044] In contrast, by distributing the subcarriers constituting the RU across a wide bandwidth, it may be possible to increase the transmission power of each subcarrier. For example, while maintaining the number of subcarriers constituting each RU, OFDMA communication can be performed using an RU composed of subcarriers that are distributed across a wider frequency bandwidth than conventional RRUs, with at least some of them not contiguous on the frequency axis. An RU configured in this way may be called a Distributed Tone RU (DRU). A DRU may also be called a Distributed RU, Enhanced RU, etc.

[0045] Furthermore, a continuous subcarrier on the frequency axis may be a subcarrier whose subcarrier index is continuous, as defined by the subcarrier indices of the subcarriers included in the OFDM symbols that constitute the PPDU. Alternatively, a continuous subcarrier on the frequency axis may be a subcarrier whose subcarrier index is continuous, excluding the subcarrier index assigned to an unused subcarrier. Regardless of the assignment of information identifying each subcarrier, such as the subcarrier index, a continuous subcarrier on the frequency axis may be a set of subcarriers arranged at predetermined intervals from lower frequencies to higher frequencies, or from higher frequencies to lower frequencies.

[0046] Here, the frequency interval between consecutive subcarriers on the frequency axis is the reciprocal of the length of the effective symbol contained in the OFDM symbol. For example, the frequency interval between consecutive subcarriers on the frequency axis is 78.125 kHz when the length of the effective symbol is the same as that in the IEEE 802.11ax or IEEE 802.11be standard.

[0047] A DRU can also be described as a RU where subcarriers constituting other RUs exist between the subcarriers that make up the DRU. In the following explanation, a RU composed of multiple subcarriers arranged to be continuous on the frequency axis will be called an RRU, and a RU composed of multiple subcarriers arranged so that at least some of the subcarriers are discontinuous on the frequency axis will be called a DRU.

[0048] However, in some cases, such as RU19 in the 26-tone RU shown in Figure 13, the subcarriers constituting the RU are separated by a DC subcarrier, resulting in a RU composed of two groups of subcarriers that are continuous on the frequency axis. Such RUs also have a high transmit power density, so they are considered to be composed of subcarriers that are essentially continuous on the frequency axis and are called RRUs rather than DRUs. Alternatively, an RU is called an RRU if there are no subcarriers constituting other RUs between the subcarriers constituting the RU, and a RU is called a DRU if there are subcarriers constituting other RUs between the subcarriers constituting the RU.

[0049] Figure 14 illustrates the concept of Coordinated OFDMA (C-OFDMA) using DRU.

[0050] The OFDM symbol 1400 shows the concept of an OFDM symbol used in C-OFDMA communication in the wireless communication system shown in Figure 1, on the frequency axis. In Figure 14, the OFDM symbol 1400 is assumed to consist of four DRUs, DRU1 to DRU4. DRU1, DRU2, DRU3, and DRU4 are assigned to STA102, STA122, STA103, and STA123, respectively. The subcarriers constituting each DRU are discontinuous and distributed across the bandwidth of the PPDU. Note that Figure 14 is merely a diagram to illustrate the concept. Therefore, the number of DRUs in a communication device to which this disclosure applies is not limited to four.

[0051] OFDM symbols 1401-1403 and OFDM symbols 1421-1423 represent the concept of OFDM symbols transmitted by each communication device shown in Figure 1 during C-OFDMA communication, shown on the frequency axis.

[0052] OFDM symbol 1401 is an OFDM symbol transmitted by AP101. AP101 transmits OFDM symbols to STA102 and STA103. Therefore, OFDM symbol 1401 consists of DRU1 and DRU3, which are assigned to STA102 and STA103, respectively.

[0053] OFDM symbol 1402 is an OFDM symbol transmitted by STA102. OFDM symbol 1402 consists of DRU1 assigned to STA102.

[0054] OFDM symbol 1403 is an OFDM symbol transmitted by STA103. OFDM symbol 1403 consists of DRU3 assigned to STA103.

[0055] OFDM symbol 1421 is an OFDM symbol transmitted by AP121. AP121 transmits OFDM symbols directed to STA122 and STA123. Therefore, OFDM symbol 1421 consists of DRU2 and DRU4, which are assigned to STA122 and STA123, respectively.

[0056] OFDM symbol 1422 is an OFDM symbol transmitted by STA122. OFDM symbol 1422 consists of DRU2 assigned to STA122.

[0057] OFDM symbol 1423 is an OFDM symbol transmitted by STA123. OFDM symbol 1423 consists of DRU4 assigned to STA123.

[0058] DRUs, like RRUs, are classified by the number of subcarriers that make up the DRU, and this classification is called the RU type. The number of subcarriers that make up a DRU may be 26, 52, 106, 242, or 484, just like with RRUs. DRUs composed of 26, 52, 106, 242, and 484 subcarriers are called 26-tone RU, 52-tone RU, 106-tone RU, 242-tone RU, and 484-tone RU, respectively.

[0059] Furthermore, each DRU is assigned an index, similar to RRUs, and this index is called the RU index. For example, if the PPDU bandwidth is 80 MHz, the range of the RU index for 26-tone RUs, 52-tone RUs, 106-tone RUs, 242-tone RUs, and 484-tone RUs may be the same as for RRUs. That is, the range of the RU index for these RUs may be RU1-RU37, RU1-RU16, RU1-RU8, RU1-RU4, and RU1-RU2. In this case, each RU is identified by a combination of RU type and RU index.

[0060] Furthermore, when the PPDU bandwidth is 160 MHz, the arrangement of each RU, that is, the relationship between each RU and the subcarrier index constituting that RU, may be the same as two RUs placed side by side on the frequency axis when the PPDU bandwidth is 80 MHz. Similarly, when the PPDU bandwidth is 320 MHz, the arrangement of each RU may be the same as four RUs placed side by side on the frequency axis when the PPDU bandwidth is 80 MHz. When the bandwidth of these PPDUs is n times 80 MHz (where n is an integer greater than or equal to 2), each RU is identified by a combination of the position of the RU in the 80 MHz bandwidth of the PPDU, the RU type, and the RU index.

[0061] The bandwidth in which the subcarriers constituting the RU are dispersed (dispersion bandwidth) is equal to the bandwidth of the PPDU when the bandwidth of the PPDU is 80 MHz or less, and may be 80 MHz when the bandwidth of the PPDU exceeds 80 MHz. Figure 14 shows the case where the dispersion bandwidth and the bandwidth of the PPDU are equal. Furthermore, the dispersion bandwidth may be equal to the bandwidth of the PPDU even when the bandwidth of the PPDU exceeds 80 MHz. Also, even when the bandwidth of the PPDU is 80 MHz or less, the dispersion bandwidth may be narrower than the bandwidth of the PPDU, and may be 20 MHz, 40 MHz, etc.

[0062] Furthermore, with respect to distributed bandwidth, it may be possible to select either a case where it is equal to the bandwidth of the PPDU or a case where it is narrower than the bandwidth of the PPDU (for example, 1 / n (where n is an integer greater than or equal to 2)) based on the capabilities and operating status of the communication device.

[0063] Figure 2 shows an example of the hardware configuration of the communication devices (AP101, AP121, STA102, STA103, STA122, and STA123) according to this embodiment.

[0064] As an example of its hardware configuration, the communication device includes, for example, a storage unit 201, a control unit 202, a functional unit 203, an input unit 204, an output unit 205, a communication unit 206, and an antenna 207, as shown in Figure 2. The communication device may have multiple antennas.

[0065] The storage unit 201 may consist of one or more memories, including ROM (Read Only Memory), RAM (Random Access Memory), etc. The storage unit 201 may store control programs for various operations of each functional unit constituting the communication device, and various information such as parameters for communication. In addition to memories such as ROM and RAM, the storage unit 201 may also consist of storage media such as flexible disks, hard disks, optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs. CD is an abbreviation for Compact Disc, CD-R is an abbreviation for Compact Disc Recordable, and DVD is an abbreviation for Digital Versatile Disc.

[0066] The control unit 202 is composed of one or more processors, such as a CPU and an MPU, and controls the entire communication device by executing a control program stored in the memory unit 201. CPU is an abbreviation for Central Processing Unit, and MPU is an abbreviation for Micro Processing Unit. The control unit 202 may also control the entire communication device in cooperation with the OS (Operating System) and the control program stored in the memory unit 201. If the control unit 202 has multiple processors that can be implemented as a multi-core or the like, the entire communication device may be controlled by multiple processors.

[0067] Furthermore, the control unit 202 controls the functional unit 203 to perform predetermined processes such as communication, imaging, printing, and projection. The functional unit 203 is hardware that enables the communication device to perform the predetermined processes described above. For example, if the device is a camera, the functional unit 203 is the imaging unit and performs imaging processing. Also, for example, if the device is a printer, the functional unit 203 is the printing unit and performs printing processing. Also, for example, if the device is a projector, the functional unit 203 is the projection unit and performs projection processing.

[0068] The input unit 204 receives various operations from the user. The output unit 205 outputs various information to the user via a monitor screen or speaker. Here, the output from the output unit 205 may be a display on the monitor screen, audio output from a speaker, vibration output, etc. The input unit 204 and the output unit 205 may both be implemented in a single module, such as a touch panel. Furthermore, the input unit 204 and the output unit 205 may each be integrated with a communication device or may be separate devices.

[0069] The communication unit 206 controls wireless communication in accordance with the IEEE 802.11bn standard. In addition to the IEEE 802.11bn standard, the communication unit 206 may also control wireless communication in accordance with other IEEE 802.11 standard series, such as legacy standards. The communication unit 206 controls the antenna 207 to transmit and receive signals for wireless communication generated by the control unit 202. The communication unit 206 is a so-called wireless chip and may itself include one or more processors and memory. The communication unit 206 is an example of a transmitting means, receiving means, or communication means according to this disclosure.

[0070] Furthermore, if the communication device supports other wireless communication standards such as NFC and Bluetooth, or wired communication such as wired LAN, in addition to the IEEE 802.11bn standard, the communication unit 206 may control communication in accordance with these communication standards. Also, if the communication device can perform wireless communication in accordance with multiple communication standards, the communication device may be configured to have separate communication units and antennas corresponding to each communication standard. The communication device communicates data with the other communication device via the communication unit 206. The antenna 207 may be configured separately from the communication unit 206, or it may be configured as a single module together with the communication unit 206.

[0071] Antenna 207 is an antenna capable of communication in the 2.4GHz band, 5GHz band, 6GHz band, millimeter wave, etc. Figure 2 shows a configuration in which the communication device has one antenna 207, but the communication device may have two or more antennas, or one or more antennas for each frequency band that the device can use. Furthermore, if the communication device has multiple antennas, the communication device may have a communication unit 206 for each antenna.

[0072] Next, the functional configuration of the communication devices (AP101, AP121, STA102, STA103, STA122, and STA123) according to this embodiment will be described. Figure 3 is a diagram showing an example of the functional configuration of the communication devices according to this embodiment.

[0073] The communication device includes, for example, a capability information storage unit 301, a DRU allocation unit 302, a frame generation and analysis unit 303, and a frame transmission and reception unit 304, as shown in Figure 3. These functions can be realized, for example, by the storage unit 201, by the control unit 202 executing a program stored in the storage unit 201, or by the processing function unit in the communication unit 206. Note that Figure 3 is a diagram illustrating the main functions in this embodiment, and other functions are omitted. For this reason, the communication device may naturally have functions for establishing connections between APs and STAs, control functions for communication, and functions that communication devices generally have. Also, the multiple function blocks shown in Figure 3 may be integrated into one function block, or one function block may be divided into multiple function blocks. Furthermore, the names of the function blocks shown in Figure 3 are merely examples and may be changed.

[0074] The capability information storage unit 301 stores capability information of the communication device (and other communication devices as necessary). The capability information includes some or all of the information indicating support for C-OFDMA, information indicating support for DRU, information indicating the type of DRU that is supported, and information indicating the distributed bandwidth of the DRU that is supported. Information indicating support for C-OFDMA can be said to be information indicating that the communication device has the capability to support C-OFDMA or information indicating that the communication device does not have the capability to support C-OFDMA. Having the capability to support C-OFDMA and supporting C-OFDMA are used interchangeably, and not having the capability to support C-OFDMA and not supporting C-OFDMA are used interchangeably. Information indicating support for DRU can be said to be information indicating that the communication device has the capability to support DRU (supports DRU) or information indicating that the communication device does not have the capability to support DRU (does not support DRU). The ability of a communication device to support C-OFDMA and DRU is used interchangeably with the ability of a communication device to support C-OFDMA using DRU (supporting C-OFDMA using DRU). The type of DRU supported can be said to be the type of DRU that the communication device supports or can use. The distributed bandwidth of the DRU supported can be said to be the distributed bandwidth of the DRU that the communication device supports or can use.

[0075] The DRU allocation unit 302 is present only in APs. The DRU allocation unit 302 negotiates with other APs regarding the DRUs to be assigned to each other during C-OFDMA communication, and determines the DRUs to be assigned. The DRU allocation unit 302 also determines the DRU to be assigned to the STA during C-OFDMA communication.

[0076] The frame generation and analysis unit 303 generates frames (and information contained in those frames (information elements, etc., described later)) to be transmitted to other communication devices, and analyzes frames received by the frame transmission / reception unit 304, described later. These frames include frames for notifying other APs and STAs connected to the device of capability information stored in the capability information storage unit 301. These frames also include frames for notifying other APs and STAs connected to the device that the DRU allocation unit 302 has negotiated or decided with other APs regarding the DRU.

[0077] The frame transmission / reception unit 304 transmits frames generated by the frame generation / analysis unit 303 and receives frames from other communication devices. These operations include media access control (MAC) in accordance with the DRU assignment determined by the DRU assignment unit 302. The frame transmission / reception unit 304 is an example of a transmission means, reception means, or communication means according to this disclosure.

[0078] Figure 4 shows an example of frame exchange between communication devices according to this embodiment.

[0079] When AP101 and AP121 are configured to enable their wireless LAN communication functions, they begin transmitting Beacon frames. Beacon frames are transmitted periodically. In Figure 4, the Beacon frames transmitted by AP101 and AP121 are represented as Beacon frames 401-403 and Beacon frames 404-406. Beacon frames 401-403 may contain an Information Element (IE) indicating that AP101 supports C-OFDMA and DRU. Beacon frames 404-406 may contain an IE indicating that AP121 supports C-OFDMA and DRU.

[0080] This IE may be an IE called the UHR Capabilities element. Figure 15 shows an example of the configuration of the UHR Capabilities element.

[0081] The UHR Capabilities element includes an Element ID field 1501, a Length field 1502, and an Element ID Extension field 1503. The Element ID Extension field 1503 may also be called the Extended Element ID field 1503. The UHR Capabilities element may also include a UHR MAC Capabilities Information field 1504 and a UHR PHY Capabilities Information field 1505.

[0082] The combination of the Element ID field 1501 and the Element ID Extension field 1503 indicates the type of element. For example, if the Element ID field 1501 is set to 255 and the Element ID Extension field 1503 is set to 138, this may indicate that the element is a UHR Capabilities element.

[0083] The Length field 1502 indicates the length of this element. The UHR MAC Capabilities Information field 1504 indicates the MAC capabilities of the communication device. The UHR PHY Capabilities Information field 1505 indicates the PHY capabilities of the communication device.

[0084] The UHR PHY Capabilities Information field 1505 includes the C-OFDMA Support field 1510. The UHR PHY Capabilities Information field 1505 includes the DRU Support field 1511. The UHR PHY Capabilities Information field 1505 includes the Supported DRU Type field 1512. The UHR PHY Capabilities Information field 1505 includes the Supported DRU Distributed Band Width field 1513.

[0085] The C-OFDMA Support field 1510 indicates whether the communication device is capable of performing C-OFDMA communication (whether it has the capability to support C-OFDMA). For example, the C-OFDMA Support field 1510 may be a 1-bit field. If the value of the C-OFDMA Support field 1510 is set to 1, it indicates that C-OFDMA communication is possible, and if the value is set to 0, it may indicate that C-OFDMA communication is not possible.

[0086] The DRU Support field 1511 indicates whether the communication device is capable of performing OFDMA communication using a DRU (i.e., whether it has the capability to support a DRU). For example, the DRU Support field 1511 can be a 1-bit field. If the DRU Support field 1511 is set to a value of 1, it indicates that OFDMA communication using a DRU is possible, and if it is set to a value of 0, it may indicate that OFDMA communication using a DRU is not possible.

[0087] Furthermore, the DRU Support field 1511 may be provided as a separate field from fields and subfields that indicate information regarding whether OFDMA communication is possible or related to OFDMA communication using RRU. This makes it possible for the communication device to independently notify whether it is possible to perform functions related to OFDMA using RRU and whether it is possible to perform OFDMA using DRU.

[0088] The Supported DRU Type field 1512 indicates the RU type (type of RU) that the communication device can use in OFDMA communication using DRUs. For example, the Supported DRU Type field 1512 can be a 3-bit field.

[0089] As an example, 26-tone RU, 52-tone RU, and 106-tone RU will be referred to as the first RU type, second RU type, and third RU type, respectively. Furthermore, 242-tone RU, 484-tone RU, and 996-tone RU will be referred to as the fourth RU type, fifth RU type, and sixth RU type, respectively.

[0090] The Supported DRU Type field 1512 can indicate the RU types available to the communication device in decimal representation. For example, if the Supported DRU Type field 1512 is set to a value of 0, it may indicate that the communication device can use the first RU type. If the Supported DRU Type field 1512 is set to a value of 1, it may indicate that the communication device can use the first and second RU types. If the Supported DRU Type field 1512 is set to a value of 2, it may indicate that the communication device can use the first through third RU types. If the Supported DRU Type field 1512 is set to a value of 3, it may indicate that the communication device can use the first through fourth RU types. If the Supported DRU Type field 1512 is set to a value of 4, it may indicate that the communication device can use the first through fifth RU types. If the Supported DRU Type field 1512 is set to a value of 5, it may indicate that the communication device can use the first through sixth RU types. The Supported DRU Type field 1512 may indicate that RUs consisting of more subcarriers than the sixth RU type are available if a value other than those listed above is set. Furthermore, the Supported DRU Type field 1512 may be set to Reserved if a value other than those listed above is set. Note that the correspondence between each decimal representation value and the RU types available to the communication device is not limited to those described above.

[0091] Furthermore, the Supported DRU Type field 1512 may indicate the RU types available to the communication device using a bitmap representation. For example, the Supported DRU Type field 1512 may be a 5-bit field, with each bit associated with a specific RU type. For instance, the first to fifth bits may each be associated with the first to fifth RU types. For example, if the value of the Nth bit is set to 1, it may indicate that the communication device can use the Nth RU type. Conversely, if the value of the Nth bit is set to 0, it may indicate that the communication device cannot use the Nth RU type. The Supported DRU Type field 1512 may also have a sixth bit, which may be associated with the sixth RU type.

[0092] The Supported DRU Distributed Bandwidth field 1513 indicates the distributed bandwidth of the DRU available to the communication device in OFDMA communication using the DRU. For example, the Supported DRU Distributed Bandwidth field 1513 can be a 3-bit field. The Supported DRU Distributed Bandwidth field 1513 can indicate the distributed bandwidth of the DRU available to the communication device in decimal representation. For example, if the Supported DRU Distributed Bandwidth field 1513 is set to a value of 0, it may indicate that the communication device can use a DRU with a distributed bandwidth of 20 MHz. For example, if the Supported DRU Distributed Bandwidth field 1513 is set to a value of 1, it may indicate that the communication device can use a DRU with a distributed bandwidth of 20 to 40 MHz. For example, if the Supported DRU Distributed Bandwidth field 1513 is set to a value of 2, it may indicate that the communication device can use a DRU with a distributed bandwidth of 20 to 80 MHz. For example, if the Supported DRU Distributed Band Width field 1513 is set to a value of 3, it may indicate that the communication device can use DRUs with a distributed bandwidth of 20 to 160 MHz. For example, if the Supported DRU Distributed Band Width field 1513 is set to a value of 4, it may indicate that the communication device can use DRUs with a distributed bandwidth of 20 to 320 MHz. For example, if the Supported DRU Distributed Band Width field 1513 is set to a value other than those mentioned above, it may indicate that the communication device can use DRUs with a distributed bandwidth other than those mentioned above. As an example, if the Supported DRU Distributed Band Width field 1513 is set to a value of 5 or 6, it may indicate that the communication device can use DRUs with a wider distributed bandwidth than those mentioned above.For example, if the Supported DRU Distributed Band Width field 1513 is set to a value of 5 or 6, it may indicate that the communication device can use DRUs with a narrower distributed bandwidth than those specified above. The Supported DRU Distributed Band Width field 1513 can also be set to any other value (Reserved).

[0093] Furthermore, the Supported DRU Distributed Band Width field 1513 can indicate the available distributed bandwidth of the communication device using a bitmap representation. For example, the Supported DRU Distributed Band Width field 1513 may be a 5-bit field, where each bit is associated with a different distributed bandwidth. As an example, the distributed bandwidths of 20MHz, 40MHz, 80MHz, 160MHz, and 320MHz may be referred to as the first, second, third, fourth, and fifth distributed bandwidths, respectively. In this case, the first to fifth bits of the Supported DRU Distributed Band Width field 1513 may be associated with the first to fifth distributed bandwidths, respectively. For example, if the value of the Nth bit is set to 1, it may indicate that the communication device can use the Nth distributed bandwidth. Conversely, if the value of the Nth bit is set to 0, it may indicate that the communication device cannot use the Nth distributed bandwidth.

[0094] Furthermore, the Supported DRU Distributed Band Width field 1513, when a predetermined value is set, indicates that the distributed bandwidth is equal to the PPDU bandwidth. On the other hand, if the Supported DRU Distributed Band Width field 1513 is not set, it may indicate that the distributed bandwidth is narrower than the PPDU bandwidth. Moreover, if the distributed bandwidth is narrower than the PPDU bandwidth, the Supported DRU Distributed Band Width field 1513 may indicate that distributed bandwidth.

[0095] The DRU Support field 1511, the Supported DRU Type field 1512, and the Supported DRU Distributed Bandwidth field 1513 may be configured as a single field. For example, a combined field formed by integrating these three fields may, in decimal representation, indicate whether the communication device can perform OFDMA communication using a DRU, the available RU types, and the available distributed bandwidth. As an example, if the combined field is set to a value of 0, it may indicate that the communication device cannot perform OFDMA communication using a DRU. If the combined field is set to a value of 1, it may indicate that the communication device can perform OFDMA communication using a DRU and that the first RU type and the first to second distributed bandwidth are available. If the combined field is set to a value of 2, it may indicate that the communication device can perform OFDMA communication using a DRU and that the first RU type and the first to second distributed bandwidths are available. The integrated field may consist of only a portion of the DRU Support field 1511, the Supported DRU Type field 1512, and the Supported DRU Distributed Bandwidth field 1513. For example, the integrated field may consist of the Supported DRU Type field 1512 and the Supported DRU Distributed Bandwidth field 1513. In this case, if the DRU Support field 1511 indicates that the communication device cannot perform OFDMA communication using a DRU, this integrated field may be omitted.

[0096] Furthermore, fields 1511, 1512, and 1513 may be fields that indicate only the capability for C-OFDMA. In this case, fields corresponding to fields 1511-1513 that indicate the capability for non-Coordinated OFDMA may be provided separately from these fields 1511-1513.

[0097] Furthermore, the C-OFDMA Support field 1510 and the DRU Support field 1511 can be configured as a single field. For example, a combined field formed by integrating these two fields can indicate, in decimal representation, whether the communication device can perform C-OFDMA communication and whether it can perform OFDMA communication using a DRU. As an example, if the combined field is set to a value of 0, it may indicate that the communication device cannot perform C-OFDMA communication. If the combined field is set to a value of 1, it may indicate that C-OFDMA communication is possible, but OFDMA communication using a DRU is not. If the combined field is set to a value of 2, it may indicate that both C-OFDMA communication and OFDMA communication using a DRU are possible.

[0098] Furthermore, fields 1510, 1511, 1512, and 1513 may be configured as a single field. For example, a combined field formed by integrating these four fields may, in decimal representation, that is, in an encoded representation where the information indicated by each field is integrated, indicate the following: that is, a combined field formed by integrating these four fields may indicate whether the communication device is capable of performing C-OFDMA communication, whether it is capable of performing OFDMA communication using a DRU, the available RU types, and the available distributed bandwidth.

[0099] Note that any, multiple, or all of fields 1510, 1511, 1512, and 1513 may be included in other fields. Any, multiple, or all of these fields may be included in the UHR MAC Capabilities Information field 1504 instead of field 1505, for example.

[0100] Furthermore, any, multiple, or all of fields 1510, 1511, 1512, and 1513 may be included in other IEs. For example, the Supported DRU Type field 1512 and the Supported DRU Distributed Band Width field 1513 may be included in the UHR Operation element.

[0101] Capability information may also be communicated using the Extended Capabilities field. In this case, the communication device can exchange capability information with a communication device that, for example, does not support the IEEE 802.11bn standard but is capable of performing C-OFDMA communication using DRU (hereinafter sometimes referred to as C-OFDMA / DRU).

[0102] Furthermore, new elements or fields may be provided for exchanging capability information regarding C-OFDMA / DRU between communication devices. These new elements or fields enable flexible exchange of information necessary for C-OFDMA / DRU communication between communication devices.

[0103] AP101 and AP121 can determine that the other AP supports C-OFDMA / DRU by receiving a Beacon frame transmitted by the other AP.

[0104] AP101 and AP121 may send a Probe Request frame to the other AP that includes an IE indicating support for C-OFDMA / DRU, in addition to the Beacon frame. Upon receiving such a frame, AP101 and AP121 may send a Probe Response frame to the other AP that includes an IE indicating support for C-OFDMA / DRU as a response.

[0105] Furthermore, AP101 and AP121 may send a Probe Response frame to the other AP that includes an IE indicating support for C-OFDMA / DRU, even if they do not receive a Probe Request frame from the other AP. The destination of this Probe Response frame may be the identifier or broadcast address of the other AP.

[0106] AP101 and AP121 can also determine that the other AP supports C-OFDMA / DRU by receiving a Probe Request frame or Probe Response frame sent by the other AP.

[0107] Furthermore, AP101 and the STA connected to AP101 may exchange information about their own devices. This information about their own devices (STAs) may include C-OFDMA / DRU information similar to that of the APs described above. AP101 and the STA connected to AP101 can exchange this information via Beacon frames, Probe Request frames, Probe Response frames, Action frames, etc. This allows AP101 and the STA connected to AP101 to know that their communication partner supports C-OFDMA / DRU.

[0108] Similarly, AP121 and the STA connected to AP121 may exchange information about themselves. This information may include C-OFDMA / DRU information similar to that of the AP described above. AP121 and the STA connected to AP121 can exchange this information via Beacon frames, Probe Request frames, Probe Response frames, Action frames, etc. This allows AP121 and the STA connected to AP121 to know that their communication partner supports C-OFDMA / DRU.

[0109] Furthermore, AP101 and AP121 may exchange information about each STA connected to AP101 and AP121, obtained by the method described above. The information about each STA may include C-OFDMA / DRU information similar to that of the AP described above. AP101 and AP121 can exchange this information via Beacon frames, Probe Request frames, Probe Response frames, Action frames, etc. AP101 and AP121 may use the same IE as the IE indicating that their device supports C-OFDMA and DRU, or they may use a different IE, in order to exchange information about each STA. Also, AP101 and AP121 may use the same frame as the frame containing the IE indicating that their device supports C-OFDMA and DRU, or they may use a different frame, in order to exchange information about each STA.

[0110] Furthermore, AP101 and AP121 may exchange C-OFDMA / DRU information regarding themselves via the wired LAN hub 150 and the wired LAN. Also, AP101 and AP121 may exchange C-OFDMA / DRU information regarding each STA connected to each of AP101 and AP121 via the wired LAN hub 150 and the wired LAN.

[0111] Figure 4 shows the C-OFDMA request phases 411 and 412. These phases are for AP101 and AP121 to negotiate and decide on the duration of the C-OFDMA data exchange phases 421-424, which will be described later. Details of the C-OFDMA request phases will be described later.

[0112] Furthermore, Figure 4 shows the C-OFDMA data exchange phases 421 to 424. Phases 421 and 423, and phases 421, 422, and phases 423 and 424 are the periods for sending and receiving data between AP101 and AP121, between AP101 and STA102 and 103, and between AP121 and STA122 and 123, respectively. Details of the C-OFDMA data exchange phases will be described later.

[0113] An AP that initiates phases 411 and 412 by sending the C-OFDMA request frame 501 (described later) or sends the Trigger frame 601 or 701 (described later) to another AP in phases 421-424 is called a Sharing AP. On the other hand, an AP that responds to the above actions by other APs is called a Shared AP. In this embodiment, AP101 is assumed to be a Sharing AP and AP121 is assumed to be a Shared AP.

[0114] Figure 5 shows an example of frames exchanged in the C-OFDMA request phase (C-OFDMA request phases 411 and 412) according to this embodiment.

[0115] AP101 sends a C-OFDMA request frame 501 to AP121. The C-OFDMA request frame 501 is a frame that requests AP121 to exchange data via C-OFDMA. The C-OFDMA request frame 501 includes information that indicates the period of C-OFDMA data exchange phases 421 to 424, as proposed by AP101 and shown in Figure 4.

[0116] When AP121 receives a C-OFDMA request frame 501, it sends a C-OFDMA response frame 502 to AP121. The C-OFDMA response frame 502 contains information indicating that AP121 accepts AP101's proposal, or information indicating a period proposed by AP121 that differs from AP101's proposal.

[0117] When AP101 receives a C-OFDMA response frame 502, it sends a C-OFDMA acknowledgment frame 503 to AP121. The C-OFDMA acknowledgment frame 503 contains either (1) or (2) of the following information. (1) Information indicating that AP101 accepts the contents of C-OFDMA response frame 502. (2) Information indicating the duration of C-OFDMA data exchange phases 421-424, determined by AP101 based on the contents of C-OFDMA response frame 502. Here, "accepting the contents of C-OFDMA response frame 502" means accepting the period proposed by AP121. Also, "determining based on the contents of C-OFDMA response frame 502" means determining the period to the period proposed by AP101 included in C-OFDMA request frame 501, in accordance with AP121's acceptance of AP101's proposal.

[0118] AP121 receives a C-OFDMA acknowledgment frame 503. Based on the information in the received frame 503 indicating the duration of C-OFDMA data exchange phases 421-424, AP121 decides to perform C-OFDMA data exchange during the duration of C-OFDMA data exchange phases 421-424. If the C-OFDMA acknowledgment frame 503 contains information indicating acceptance of the contents of the C-OFDMA response frame 502, the duration of C-OFDMA data exchange phases 421-424 is implicitly indicated as the duration proposed by AP121. In this case, since the duration proposed by AP121 is used, there is no discrepancy in understanding between AP101 and AP121, even if the duration of C-OFDMA data exchange phases 421-424 is not explicitly included in the C-OFDMA acknowledgment frame 503.

[0119] The C-OFDMA request frame 501, C-OFDMA response frame 502, and / or C-OFDMA confirmation frame 503 may also contain information regarding the allocation of DRUs applicable to C-OFDMA data exchange phases 421-424. The AP determines the allocation of DRUs based on the C-OFDMA / DRU capability information of other APs obtained via Beacon frames, Probe Request frames, Probe Response frames, etc.

[0120] Information regarding DRU allocation may include information indicating the DRU allocation for each STA. For example, in the example shown in Figure 14, the information regarding DRU allocation may include information indicating that DRU1, DRU3, DRU2, and DRU4 are allocated to STA102, STA103, STA122, and STA123, respectively.

[0121] Furthermore, the information regarding DRU allocation may include information indicating the DRU allocation for each AP, or in other words, for each BSS managed by the AP. For example, in the example shown in Figure 14, the information regarding DRU allocation may include information indicating that DRU3 and DRU4 are allocated to AP101 and AP121, respectively.

[0122] If AP101 and AP121 reject data exchange via C-OFDMA or the other AP's proposal, they will send a C-OFDMA response frame 502 or C-OFDMA acknowledgment frame 503 to the other AP, including information indicating this rejection. In this case, C-OFDMA data exchange phases 421 to 424 will not be performed. If AP101 receives a C-OFDMA response frame 502 from AP121 containing information indicating rejection, it will not send a C-OFDMA acknowledgment frame 503.

[0123] When AP101 receives the C-OFDMA response frame 502, it may transmit an acknowledgement (ACK) frame indicating that it has received the frame to AP121. Also, when AP121 receives the C-OFDMA request frame 501, it may transmit an ACK frame indicating that it has received the frame to AP101. Further, when AP121 receives the C-OFDMA confirmation frame 503, it may transmit an ACK frame indicating that it has received the frame to AP101.

[0124] FIG. 6 is a diagram showing an example of frames exchanged in the C-OFDMA data exchange phase (C-OFDMA data exchange phases 421 to 424) according to an embodiment. FIG. 6 shows an example of data transmission in the downlink (DL: Downlink).

[0125] When it comes to the periods of the C-OFDMA data exchange phases 421 to 424 determined in the C-OFDMA request phases 411 and 412, AP101 transmits the Trigger frame 601 to AP121. The Trigger frame 601 is an example of a frame that requests other APs to perform data transmission (data communication, data exchange) by C-OFDMA using the DRU by a communication device belonging to a BSS managed by another AP.

[0126] FIG. 16 is a diagram showing a configuration example of the Trigger frame. The Trigger frame 601 includes a Frame Control field 1601, a Common Info field 1602, and a User Info List field 1603.

[0127] The Frame Control field 1601 includes a Type subfield 1611 and a Subtype subfield 1612. These fields indicate the function of the frame.

[0128] The Type subfield 1611 indicates whether the frame is Management, Control, or Data. In the case of Trigger frame 601, the Type subfield 1611 has a value indicating that it is Control.

[0129] The Subtype subfield 1612 indicates the frame's subtype. Subtypes include Probe Request, Probe Response, Beacon, RTS, CTS, Block Ack, Ack, Data, Trigger, etc. In the case of a Trigger frame 601, the Subtype subfield 1612 has a value indicating that it is a Trigger. However, in the case of a Trigger frame 601, the Subtype subfield 1612 may have a value indicating that it is a Trigger for data exchange via C-OFDMA, rather than simply indicating that it is a Trigger.

[0130] The Common Info field 1602 contains information common to the communication device targeted by the Trigger frame. The Common Info field 1602 includes the Trigger Type subfield 1621 and the UL BW subfield 1622.

[0131] The Trigger Type subfield 1621 indicates the variant of the Trigger frame. Variants include Basic, MU-RTS, etc. In the case of Trigger frame 601, the Trigger Type subfield 1621 has a value indicating that it is a Trigger frame for data exchange via C-OFDMA.

[0132] The UL BW subfield 1622, along with the UL Bandwidth Extension subfield 1641 (described later), indicates the frequency bandwidth of the data frame whose transmission is triggered by the Trigger frame. This subfield may also be named the DL BW subfield.

[0133] The User Info List field 1603 contains the Special User Info field 1631 and the User Info field 1632. There are typically multiple User Info fields, each corresponding to the destination of the data frame triggered by the Trigger frame.

[0134] The Special User Info field 1631 is a field that extends the Common Info field 1602. Like the Common Info field 1602, the Special User Info field 1631 contains information common to the communication device targeted by the Trigger frame. The Special User Info field 1631 includes the UL Bandwidth Extension subfield 1641.

[0135] The UL Bandwidth Extension subfield 1641, along with the UL BW subfield 1622, indicates the frequency bandwidth of the data frame whose transmission is triggered by the Trigger frame. This subfield may also be named the DL Bandwidth Extension subfield.

[0136] Here, the UL BW subfield 1622 may have a value indicating a frequency bandwidth of 20 MHz, 40 MHz, 80 MHz, 160 MHz, or wider than 160 MHz. The UL Bandwidth Extension subfield 1641 may take a value indicating 20 MHz, 40 MHz, 80 MHz, 160 MHz, or 320 MHz. The UL Bandwidth Extension subfield 1641 may also have a value other than those listed above, such as 640 MHz.

[0137] In the case of Trigger frame 601, the UL BW subfield 1622 and the UL Bandwidth Extension subfield 1641 indicate the frequency bandwidths of the Multi-User (MU) PPDU 602 and MU PPDU 603.

[0138] The User Info field 1632 contains information about the communication device for one of the destinations of the data frame whose transmission is triggered by the Trigger frame. The User Info field 1632 includes the AID12 subfield 1651, the RU Allocation subfield 1652, and the PS160 subfield 1653.

[0139] The AID12 subfield 1651 contains an identifier for identifying the communication device targeted by the User Info field 1632.

[0140] The RU Allocation subfield 1652 includes information indicating whether the RU assigned to the communication device targeted by the User Info field 1632 is an RRU or a DRU, and information indicating the RU index. The information indicating whether the RU is an RRU or a DRU is included in the information indicating the RU index, and whether the RU is an RRU or a DRU may be distinguished by the value of the RU index. Also, the bits containing the information indicating whether the RU is an RRU or a DRU may be different from the bits indicating the information indicating the RU index. The RU Allocation subfield 1652, together with the PS 160 subfield 1653, may include information indicating which 80MHz band the RU is located in when the PPDU bandwidth is wider than 80MHz.

[0141] The PS 160 subfield 1653, together with the RU Allocation subfield 1652, may include information indicating which 80 MHz band the RU is located in when the PPDU bandwidth is wider than 80 MHz. More specifically, the PS 160 subfield 1653 may include information indicating which 80 MHz band the RU assigned to the communication device covered by the User Info field 1632 is located in.

[0142] The positions of the RRU and DRU on the frequency axis are determined by at least the values ​​of the UL BW subfield 1622 and the RU Allocation subfield 1652. The positions of the RRU and DRU on the frequency axis may also be determined by considering one or both of the values ​​of the UL Bandwidth Extension subfield 1641 and the PS 160 subfield 1653.

[0143] The AP determines the information regarding the allocation of the DRU mentioned above based on the capability information regarding C-OFDMA / DRU of other APs obtained through Beacon frames, Probe Request frames, Probe Response frames, etc.

[0144] Furthermore, the Trigger frame 601 may contain information indicating that the Trigger frame 601 is for data transmission via DL.

[0145] Returning to the explanation of Figure 6, AP101 sends Trigger frame 601 to AP121, and then sends MU PPDU 602 containing data to STA102 and STA103 to STA102 and STA103. MU PPDU 602 includes information indicating the DRU assigned to each of STA102, STA103, STA122, and STA123 in the RU Allocation subfield within the Common Info field. The data for STA102 and STA103 is contained in the DRU assigned to each of STA102 and STA103 in the Data field.

[0146] AP121 receives a Trigger frame 601 from AP101. This allows AP121 to identify the DRU assigned to each of the STAs: STA102, STA103, STA122, and STA123. If the aforementioned C-OFDMA request frame 501 or C-OFDMA acknowledgment frame 503 contains information indicating the DRU assigned to each of these STAs, AP121 may identify the DRU from that frame.

[0147] After receiving Trigger frame 601, AP121 sends MU PPDU 603 containing data to STA122 and STA123 to STA122 and STA123. MU PPDU 603 includes information indicating the DRU assigned to each of STA102, STA103, STA122, and STA123 in the RU Allocation subfield within the Common Info field. The data for STA122 and STA123 is contained in the DRU assigned to each of STA122 and STA123 within the Data field.

[0148] Here, the time from when AP101 finishes sending Trigger frame 601 until it sends MU PPDU 602 is equal to the time from when AP121 finishes receiving Trigger frame 601 until it sends MU PPDU 603. Therefore, MU PPDU 602 and MU PPDU 603 are sent simultaneously. This enables the transmission of MU PPDUs using C-OFDMA.

[0149] Upon receiving the MU PPDU 602, STA102 and STA103 retrieve data from the DRU assigned to their respective devices using information indicating the DRU assigned to them. Subsequently, STA102 and STA103 send a Block ACK frame 604 to AP101 containing information indicating an acknowledgment to the DRU assigned to them.

[0150] Similarly, upon receiving the MU PPDU 603, STA122 and STA123 retrieve data from the DRU assigned to their respective devices using information indicating the DRU assigned to them. Subsequently, STA122 and STA123 send a Block ACK frame 605 to AP121 containing information indicating an acknowledgment to the DRU assigned to them.

[0151] AP101 may send a Request to Send (RTS) frame 606 to AP121 prior to sending the Trigger frame 601. The RTS frame 606 may contain information indicating the DRU assigned to STA102, STA103, STA122, and STA123, respectively.

[0152] When AP121 receives RTS frame 606, it sends Clear to Send (CTS) frame 607 to AP101.

[0153] RTS frame 606 and CTS frame 607 contain information indicating the duration of the Transmission Opportunity (TXOP) reserved by AP101. The period for performing data exchange via C-OFDMA may be reserved by sending RTS frame 606 and CTS frame 607. In this case, the aforementioned C-OFDMA request phases 411 and 412 may not be performed.

[0154] Furthermore, the Trigger frame 601 transmitted by AP101 may include information indicating the DRU assigned to AP101 and AP121, respectively. In this case, the Trigger frame 601 transmitted by AP101 does not need to include information indicating the DRU assigned to STA102, STA103, STA122, and STA123, respectively. Thus, the Trigger frame 601 transmitted by AP101 may include information indicating the DRU that can be assigned to STA122 and STA123, which are STAs belonging to a BSS managed by another AP, AP121. Furthermore, the Trigger frame 601 transmitted by AP101 may include information indicating the DRU that can be assigned to STA102 and STA103, which are STAs belonging to a BSS managed by AP101. And in MU PPDU 602, the DRU assigned to AP101 may include information indicating the DRU assigned to STA102 and STA103, respectively. Similarly, in MU PPDU603, the DRU assigned to AP121 may include information indicating the DRUs assigned to STA122 and STA123, respectively.

[0155] In this case, the User Info field 1632 shown in Figure 16 exists for each AP to which a DRU is assigned, and each of these User Info fields 1632 may contain information for one AP to which a DRU is assigned. Alternatively, each of these User Info fields 1632 may not contain information for one STA to which a DRU is assigned. Therefore, in this case, the User Info field 1632 can be considered a separate AP information field for each AP. For example, the AID12 subfield 1651 may contain information for identifying the AP, and the RU Allocation subfield 1652 may contain information indicating the DRU assigned to the AP. In this case, the DRU assigned to AP101 and the DRU assigned to AP121 are present in the preamble (PHY header) or MAC header of the MU PPDU 602 multiplexed on the frequency axis using the OFDMA method. Alternatively, a separate AP information field for each AP, having a similar structure to the User Info field 1632, may be newly introduced in the Trigger frame 601.

[0156] Figure 7 shows another example of frames exchanged in the C-OFDMA data exchange phase (C-OFDMA data exchange phases 421-424) according to the embodiment. Figure 7 shows an example of data transmission over the uplink (UL).

[0157] When AP101 reaches the period of C-OFDMA data exchange phases 421-424 determined in C-OFDMA request phases 411 and 412, it sends a Trigger frame 701 to AP121. The Trigger frame 701 is an example of a frame that requests other APs to perform C-OFDMA data transmission (data communication, data exchange) using DRU by a communication device belonging to a BSS managed by another AP.

[0158] The configuration of Trigger frame 701 is the same as that shown in Figure 16. However, in the case of Trigger frame 701, the UL BW subfield 1622 and the UL Bandwidth Extension subfield 1641 indicate the frequency bandwidths of TB PPDU 704 and TB PPDU 705. TB is an abbreviation for Trigger Based.

[0159] Additionally, the User Info field 1632 contains information about the communication device that is the source of one of the data frames whose transmission is triggered by the Trigger frame.

[0160] The AP determines the information regarding the allocation of the DRU mentioned above based on the capability information regarding C-OFDMA / DRU of other APs obtained through Beacon frames, Probe Request frames, Probe Response frames, etc.

[0161] Furthermore, the Trigger frame 601 may contain information indicating that the Trigger frame 601 is for data transmission via UL.

[0162] AP101 sends Trigger frame 701 to AP121, and then sends Trigger frame 702 to STA102 and STA103. Trigger frame 702 has the same configuration as Trigger frame 701 in terms of the portion relating to DRU allocation.

[0163] When AP121 receives Trigger frame 701 from AP101, it transmits Trigger frame 703 to STA122 and STA123. Trigger frame 703 has the same configuration as Trigger frame 702.

[0164] Here, the time from AP101 completing the transmission of Trigger frame 701 to the start of transmission of Trigger frame 702 is equal to the time from AP121 completing the reception of Trigger frame 701 to the start of transmission of Trigger frame 703. Therefore, Trigger frame 702 and Trigger frame 703 are transmitted simultaneously.

[0165] STA102 and STA103 receive Trigger frame 702. This allows STA102 and STA103 to identify the DRU assigned to their respective devices. Upon receiving Trigger frame 702, STA102 and STA103 send TB PPDU 704 containing data to AP101 to the DRU assigned to each of them.

[0166] Similarly, STA122 and STA123 receive Trigger frame 703. This allows STA122 and STA123 to identify the DRU assigned to their respective devices. Upon receiving Trigger frame 703, STA122 and STA123 send TB PPDU 705 containing data to AP121 to the DRU assigned to each of them.

[0167] Here, the time from the completion of reception of Trigger frame 702 to the start of transmission of TB PPDU 704 is equal to the time from the completion of reception of Trigger frame 703 to the start of transmission of TB PPDU 705. The reception of Trigger frame 702 and the transmission of TB PPDU 704 are performed by STA102 and STA103, while the reception of Trigger frame 703 and the transmission of TB PPDU 705 are performed by STA122 and STA123. This enables the transmission of TB PPDUs using C-OFDMA.

[0168] Upon receiving TB PPDU 704, AP101 retrieves data from STA102 and STA103 from the DRUs assigned to each of them. AP101 then sends a Block ACK frame 706 containing acknowledgment information to the DRUs assigned to each of STA102 and STA103.

[0169] Similarly, upon receiving the TB PPDU 705, AP121 retrieves data from STA122 and STA123 from the DRUs assigned to each of them. AP121 then sends a Block ACK frame 707 to STA122 and STA123 containing acknowledgment information to the DRUs assigned to each of them.

[0170] Furthermore, AP101 may send an RTS frame 606 to AP121 prior to sending the Trigger frame 601, similar to the case where DL data is transmitted as described using Figure 6. The RTS frame 606 may contain information indicating the DRU assigned to each of STA102, STA103, STA122, and STA123.

[0171] When AP121 receives RTS frame 606, it sends CTS frame 607 to AP101.

[0172] RTS frame 606 and CTS frame 607 contain information indicating the duration of the TXOP reserved by AP101. The period for performing data exchange via C-OFDMA may be reserved by sending RTS frame 606 and CTS frame 607. In this case, the aforementioned C-OFDMA request phase may not be performed.

[0173] Furthermore, the Trigger frame 701 transmitted by AP101 may include information indicating the DRU assigned to AP101 and AP121, respectively. In this case, the Trigger frame 701 transmitted by AP101 does not need to include information indicating the DRU assigned to STA102, STA103, STA122, and STA123, respectively. Thus, the Trigger frame 701 transmitted by AP101 may include information indicating the DRU that can be assigned to STA122 and STA123, which are STAs belonging to a BSS managed by another AP, AP121. Furthermore, the Trigger frame 701 transmitted by AP101 may include information indicating the DRU that can be assigned to STA102 and STA103, which are STAs belonging to a BSS managed by AP101.

[0174] In this case, the User Info field 1632 shown in Figure 16 in the Trigger frame 701 may exist as many times as there are APs to which a DRU is assigned. Each of these User Info fields 1632 may contain information for one AP to which a DRU is assigned. In this case, each of these User Info fields 1632 may not contain information for one STA to which a DRU is assigned. Therefore, in this case, the User Info field 1632 can be considered a separate AP information field for each AP. For example, the AID12 subfield 1651 may contain information for identifying the AP, and the RU Allocation subfield 1652 may contain information indicating the DRU assigned to the AP. Alternatively, a separate AP information field for each AP, having a similar structure to the User Info field 1632, may be newly introduced in the Trigger frame 701. Then, in the Trigger frame 702, the DRU assigned to AP101 may include information indicating the DRUs assigned to STA102 and STA103, respectively. Similarly, in Trigger frame 703, the DRU assigned to AP121 may include information indicating the DRUs assigned to STA122 and STA123, respectively.

[0175] Figure 8 is a flowchart illustrating an example of AP operation related to the exchange of information indicating the capability to support C-OFDMA / DRU between APs, according to the embodiment. The operation shown in Figure 8 is initiated when the user or other party enables the wireless LAN function of the AP.

[0176] In step S801, the AP determines whether it is time to send a Beacon frame. If the AP determines that it is time to send a Beacon frame (Yes in step S801), it proceeds to step S802. On the other hand, if the AP determines that it is not time to send a Beacon frame (No in step S801), it proceeds to step S803.

[0177] In step S802, the AP sends a Beacon frame. Then the AP proceeds to step S803. As illustrated using Figure 4, the Beacon frame may contain an IE indicating that the AP supports C-OFDMA / DRU.

[0178] In step S803, the AP determines whether it has received a Beacon frame transmitted by another AP. If the AP determines that it has received a Beacon frame (Yes in step S803), it proceeds to step S804. On the other hand, if the AP determines that it has not received a Beacon frame (No in step S803), it proceeds to step S805.

[0179] In step S804, the AP analyzes the received Beacon frame and stores the capabilities of other APs. If the Beacon frame contains an IE indicating that the AP supports C-OFDMA / DRU, the AP also stores this information. Then the AP proceeds to step S805.

[0180] In step S805, the AP determines whether the user has disabled the wireless LAN function. If the AP determines that the wireless LAN function has been disabled (Yes in step S805), it terminates this operation. On the other hand, if the AP determines that the wireless LAN function has not been disabled (No in step S805), it returns to step S801.

[0181] Figure 9 is a flowchart illustrating an example of AP operation during the C-OFDMA request phase (C-OFDMA request phases 411 and 412) according to the embodiment. The operation shown in Figure 9 is initiated when data to be transmitted via C-OFDMA is generated at the AP or STA, or when such generation is foreseen.

[0182] In step S901, the AP determines whether it has received a C-OFDMA request frame (C-OFDMA request frame 501 shown in Figure 5). If the AP determines that it has received a C-OFDMA request frame (Yes in step S901), it proceeds to step S902. On the other hand, if the AP determines that it has not received a C-OFDMA request frame (No in step S901), it proceeds to step S907.

[0183] In step S902, the AP determines whether to accept the contents of the received C-OFDMA request frame. If the AP decides to accept the contents of the C-OFDMA request frame (Yes in step S902), it proceeds to step S903. On the other hand, if the AP decides not to accept the contents of the C-OFDMA request frame (No in step S902), it proceeds to S906.

[0184] In step S903, the AP sends back a C-OFDMA response frame (C-OFDMA response frame 502 shown in Figure 5) indicating acceptance of the contents of the C-OFDMA request frame or the conditions for acceptance (e.g., a period). Then the AP proceeds to step S904.

[0185] In step S904, the AP determines whether it has received a C-OFDMA acknowledgment frame (C-OFDMA acknowledgment frame 503 shown in Figure 5) indicating acceptance of the contents of the transmitted C-OFDMA response frame. If the AP determines that it has received a C-OFDMA acknowledgment frame (Yes in step S904), it proceeds to step S905. On the other hand, if the AP determines that it has not received a C-OFDMA acknowledgment frame (No in step S904), it proceeds to step S913.

[0186] In step S905, the AP stores the scheduled execution of C-OFDMA. Then, the AP proceeds to step S913.

[0187] If the AP determines in step S902 that it does not accept the contents of the received C-OFDMA request frame, it sends back a C-OFDMA response frame (C-OFDMA response frame 502 shown in Figure 5) in step S906. This C-OFDMA response frame indicates that the AP refuses to perform the C-OFDMA.

[0188] Furthermore, if the AP determines in step S901 that it has not received a C-OFDMA request frame, it sends a C-OFDMA request frame to the AP with which it is jointly performing the C-OFDMA data exchange phase in step S907. The C-OFDMA request frame sent to the AP with which it is jointly performing the C-OFDMA data exchange phase corresponds to the C-OFDMA request frame 501 shown in Figure 5. Then the AP proceeds to step S908.

[0189] In step S908, the AP determines whether it has accepted the contents of the transmitted C-OFDMA request frame or has received a C-OFDMA response frame (C-OFDMA response frame 502 shown in Figure 5) indicating the conditions for acceptance. If the AP determines that it has received a C-OFDMA response frame (Yes in step S908), it proceeds to step S909. On the other hand, if the AP determines that it has not received a C-OFDMA response frame (No in step S908), it proceeds to step S913.

[0190] In step S909, the AP determines whether to accept the contents of the received C-OFDMA response frame. If the AP decides to accept the contents of the C-OFDMA response frame (Yes in step S909), it proceeds to step S910. On the other hand, if the AP decides not to accept the contents of the C-OFDMA response frame (No in step S909), it proceeds to step S912.

[0191] In step S910, the AP sends back a C-OFDMA acknowledgment frame (C-OFDMA acknowledgment frame 503 shown in Figure 5) indicating that it accepts the contents of the C-OFDMA response frame. Then the AP proceeds to step S911.

[0192] In step S911, the AP stores the scheduled execution of C-OFDMA. Then, the AP proceeds to step S913.

[0193] If the AP determines in step S908 that it has not received a C-OFDMA response frame, it proceeds to step S913.

[0194] Furthermore, if the AP determines in step S909 that it does not accept the contents of the received C-OFDMA response frame, it sends back a C-OFDMA confirmation frame in step S912 indicating that it refuses to perform the C-OFDMA. The C-OFDMA confirmation frame indicating the refusal to perform the C-OFDMA corresponds to the C-OFDMA confirmation frame 503 shown in Figure 5. Then the AP proceeds to step S913.

[0195] In step S913, the AP determines whether the user has disabled the wireless LAN function. If the AP determines that the wireless LAN function has been disabled (Yes in step S913), it terminates this operation. On the other hand, if the AP determines that the wireless LAN function has not been disabled (No in step S913), it returns to step S901.

[0196] Figure 10 is a flowchart showing an example of AP operation during the C-OFDMA data exchange phase (C-OFDMA data exchange phases 421-424) according to the embodiment. The operation shown in Figure 10 starts when C-OFDMA data exchange phases 421-424 begin.

[0197] In step S1001, the AP determines whether its device is a Sharing AP. If the AP determines that its device is a Sharing AP (Yes in step S1001), it proceeds to step S1002. On the other hand, if the AP determines that its device is not a Sharing AP (No in step S1001), it proceeds to step S1008.

[0198] In step S1002, the AP determines whether it plans to send data to the STA connected to its device. If the AP determines that it plans to send data (Yes in step S1002), it proceeds to step S1003. On the other hand, if the AP determines that it does not plan to send data (No in step S1002), it proceeds to step S1005.

[0199] In step S1003, the AP sends a Trigger frame (Trigger frame 601 shown in Figure 6) to the Shared AP to send DL data.

[0200] As illustrated with Figure 16, the Trigger frame 601 includes information indicating that it is a Trigger frame for data transmission via C-OFDMA and information indicating the assignment of an RRU or DRU. The AP may select which RU to use based on the frequency band being used, the distance to the STA which is the data destination, etc. For example, a DRU may be used when using the 6GHz band, which allows for a lower power density compared to other frequency bands, and an RRU may be used otherwise. Also, for example, a DRU may be used when the distance to at least one, or a predetermined number or more, of the STAs which are the data destinations is considered to be long, and an RRU may be used otherwise. The AP may estimate the distance to the STA, for example, based on the strength of the signal received from that STA.

[0201] When the AP sends a Trigger frame, it proceeds to step S1004.

[0202] In step S1004, the AP sends an MU PPDU (MU PPDU 602 or 603 shown in Figure 6) containing data for the STA to the RU assigned to the STA connected to its device. Then the AP proceeds to step S1010.

[0203] If the AP determines in step S1002 that it does not intend to send data to the STA connected to its own device, in step S1005 it sends a Trigger frame to the Shared AP to prompt the STA to send UL data. The Trigger frame to prompt the STA to send UL data corresponds to Trigger frame 701 shown in Figure 7. Then the AP proceeds to step S1006.

[0204] In step S1006, the AP sends a Trigger frame (Trigger frame 702 or 703 shown in Figure 7) to the STA connected to its device to cause the STA to send UL data. Then the AP proceeds to step S1007.

[0205] As explained using Figure 16, Trigger frames 701-703 include information indicating that they are Trigger frames for data transmission via C-OFDMA and information indicating the assignment of an RRU or DRU. The AP may select which RU to use based on the frequency band used, the distance to the STA that is the data source, etc. For example, if using the 6GHz band, which allows for a lower power density compared to other frequency bands, a DRU may be used, and otherwise an RRU may be used. Also, for example, if the distance to at least one, or a predetermined number or more, of the STAs that are data sources is considered to be long, a DRU may be used, and otherwise an RRU may be used. The AP may estimate the distance to the STA, for example, based on the strength of the signal received from that STA.

[0206] In step S1007, the AP receives a TB PPDU (TB PPDU 704 or 705 shown in Figure 7) from the STA that is the source of the data specified in the Trigger frame (Trigger frame 702 or 703 shown in Figure 7). Upon receiving the TB PPDU, the AP retrieves the data transmitted by each STA from the RU assigned to the STA. The AP then sends back a Block ACK frame (Block ACK frame 706 or 707 shown in Figure 7). The AP then proceeds to step S1010.

[0207] If the AP determines in step S1001 that its device is a Shared AP and not a Sharing AP, it determines in step S1008 whether it has received a Trigger frame. The Trigger frame that is determined to have been received in step S1008 corresponds to Trigger frame 601 shown in Figure 6 or Trigger frame 701 shown in Figure 7. If the AP determines that it has received a Trigger frame (Yes in step S1008), it proceeds to step S1009. On the other hand, if the AP determines that it has not received a Trigger frame (No in step S1008), it proceeds to step S1010.

[0208] In step S1009, the AP determines whether the received Trigger frame is for transmitting DL data (Trigger frame 601 shown in Figure 6). If the AP determines that the Trigger frame is for transmitting DL data (Yes in step S1009), it proceeds to step S1004. On the other hand, if the AP determines that the Trigger frame is not for transmitting DL data (No in step S1009), it proceeds to step S1007. If the Trigger frame is not for transmitting DL data, it means that it is for causing the STA to transmit UL data (Trigger frame 701 shown in Figure 7).

[0209] If the AP determines in step S1008 that it has not received a Trigger frame (Trigger frame 601 shown in Figure 6 or Trigger frame 701 shown in Figure 7), it proceeds to step S1010.

[0210] In step S1010, the AP determines whether the C-OFDMA data exchange phase has ended. If the AP determines that the C-OFDMA data exchange phase has ended (Yes in step S1010), it terminates this operation. On the other hand, if the AP determines that the C-OFDMA data exchange phase has not ended (No in step S1010), it returns to step S1001.

[0211] Figure 11 is a flowchart illustrating an example of STA operation according to an embodiment. The operation shown in Figure 11 begins when the STA connects to (associates with) the AP. Note that Figure 11 only describes operations related to data exchange by C-OFDMA relevant to this disclosure.

[0212] In step S1101, the STA determines whether it has received a Trigger frame indicating UL transmission from the connected AP (Trigger frame 702 or 703 shown in Figure 7). If the STA determines that it has received a Trigger frame indicating UL transmission (Yes in step S1101), it proceeds to step S1102. On the other hand, if the STA determines that it has not received a Trigger frame indicating UL transmission (No in step S1101), it proceeds to step S1103.

[0213] In step S1102, the STA sends a TB PPDU (TB PPDU704 or 705 shown in Figure 7) containing data in the RRU or DRU indicated in the Trigger frame to the connected AP. Then the STA proceeds to step S1104.

[0214] If the STA determines in step S1101 that it has not received a Trigger frame indicating UL transmission from the AP (No in step S1101), it waits for an MU PPDU from the AP (MU PPDU 602 or 603 shown in Figure 6). If the STA receives an MU PPDU, it acquires data from the RRU or DRU assigned to its device as indicated in the MU PPDU (step S1103). Then the STA proceeds to step S1104.

[0215] In step S1104, the STA determines whether the user has disabled the wireless LAN function (or whether the connection from the AP has been disconnected (disassociated or deassociated)). If the STA determines that the wireless LAN function has been disabled (or the connection from the AP has been disconnected) (Yes in step S1104), it terminates this operation. On the other hand, if the STA determines that the wireless LAN function has not been disabled (and the connection from the AP has not been disconnected) (No in step S1104), it returns to step S1101.

[0216] According to the embodiment described above, AP101 sends a frame (e.g., Trigger frame 601 or 701) requesting AP121 or STA122, 123 to perform data transmission using C-OFDMA with DRU. This allows AP121 or STA122, 123 to know that C-OFDMA with DRU is being applied to data transmission. Therefore, it becomes possible to appropriately apply DRU to C-OFDMA in BSS.

[0217] <Other Embodiments> The embodiments described above show an example in which two APs (BSSs) communicate using C-OFDMA with DRUs, but this disclosure is not limited to two APs (BSSs). That is, in other embodiments, three or more APs (BSSs) may communicate using C-OFDMA with DRUs. In this case, one of the three or more APs may operate as a Sharing AP, and the remaining three or more APs may operate as Shared APs. Specifically, the APs operate as follows.

[0218] Each AP exchanges information with other APs via Beacon frames, Probe Request frames, Probe Response frames, Action frames, etc., indicating that its device supports C-OFDMA and DRU. This allows each AP to know that other APs support C-OFDMA and DRU.

[0219] The Sharing AP sends a C-OFDMA request frame to the Shared AP to request data exchange via C-OFDMA. The C-OFDMA request frame includes information indicating the duration of the C-OFDMA data exchange phase proposed by the Sharing AP. The C-OFDMA request frame may have a similar structure to the Trigger frame described above (for example, Trigger frame 601 shown in Figure 6 or Trigger frame 701 shown in Figure 7). For example, the User Info field of the Trigger frame may be used as a separate AP information field for each AP, or a new separate AP information field may be introduced for each AP, having a similar structure to the User Info field.

[0220] When a Shared AP receives a C-OFDMA request frame, it sends a C-OFDMA response frame to the Sharing AP. The C-OFDMA response frame contains information indicating that the Shared AP accepts the Sharing AP's proposal.

[0221] When a Sharing AP receives a C-OFDMA response frame, it sends a C-OFDMA acknowledgment frame to the Shared APs. The C-OFDMA acknowledgment frame contains information indicating the duration of the C-OFDMA data exchange phase, which the Sharing AP has determined based on the contents of the C-OFDMA response frame. "Determined based on the contents of the C-OFDMA response frame" means that the duration is determined to be the duration proposed by the Sharing AP, as included in the C-OFDMA request frame, depending on whether all Shared APs have accepted the Sharing AP's proposal.

[0222] The Shared AP receives a C-OFDMA acknowledgment frame. Based on the information in the received frame indicating the duration of the C-OFDMA data exchange phase, the Shared AP then decides to perform C-OFDMA data exchange during the duration of the C-OFDMA data exchange phase.

[0223] Furthermore, the C-OFDMA request frame, C-OFDMA response frame, and / or C-OFDMA confirmation frame may contain information regarding the allocation of DRUs applicable to the C-OFDMA data exchange phase. The AP determines the DRU allocation based on the C-OFDMA / DRU capability information of other APs obtained via Beacon frames, Probe Request frames, Probe Response frames, etc.

[0224] Information regarding DRU allocation may include information indicating DRU allocation for each STA. Furthermore, information regarding DRU allocation may include information indicating DRU allocation for each AP, or in other words, for each BSS managed by the AP.

[0225] If a Shared AP rejects a C-OFDMA data exchange or a Sharing AP's proposal, it will send a C-OFDMA response frame to the Sharing AP indicating this rejection. In this case, the C-OFDMA data exchange phase will not be performed. If a Sharing AP receives a C-OFDMA response frame from any of the Shared APs that includes information indicating rejection, it will not send a C-OFDMA acknowledgment frame.

[0226] When a Sharing AP receives a C-OFDMA response frame, it may send an ACK frame to the Shared AP indicating that it has received the frame. Furthermore, when a Shared AP receives a C-OFDMA request frame or an OFDMA acknowledgment frame, it may send an ACK frame to the Sharing AP indicating that it has received the frame.

[0227] The operation during the C-OFDMA data exchange phase in other embodiments is the same as or similar to the operation during the C-OFDMA data exchange phase in the embodiments described above, so a description is omitted.

[0228] This disclosure can also be implemented by supplying a program that implements one or more of the functions of the embodiments described above to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. Furthermore, this disclosure can also be implemented by a circuit (e.g., an Application Specific Integrated Circuit (ASIC)) that implements one or more functions.

[0229] Furthermore, some of the processes described in this disclosure with reference to the flowchart may be implemented in hardware. For example, by using a predetermined compiler, a dedicated circuit can be automatically generated on a Field Programmable Gate Array (FPGA) from the program to implement each step. Alternatively, a Gate Array circuit may be formed in the same way as an FPGA and implemented in hardware.

[0230] Furthermore, the following additional information is disclosed regarding the above embodiments.

[0231] [Note 1] A communication device that functions as an Access Point (AP) as defined in the IEEE 802.11 standard series, A transmission means that transmits a frame requesting that a communication device belonging to a Basic Service Set (BSS) managed by another AP perform data transmission using Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) with a Distributed Tone Resource Unit (DRU). A communication device equipped with the following features.

[0232] [Note 2] The communication device belonging to the aforementioned BSS is the other AP described in Appendix 1.

[0233] [Note 3] The communication equipment belonging to the aforementioned BSS is a non-AP Station (non-AP STA) as defined in the IEEE 802.11 standard series, as described in Appendix 1 or 2.

[0234] [Note 4] The aforementioned frame includes information relating to a DRU assigned to a non-AP STA belonging to the BSS, as described in any of the communications devices described in Appendix 1 to 3.

[0235] [Note 5] The communication device according to any one of the appendices 1 to 4, wherein the frame includes information about a DRU that the other AP can assign to a non-AP STA belonging to the BSS.

[0236] [Note 6] The aforementioned frame is a type of trigger frame defined in the IEEE 802.11 standard series, and is a communication device as described in any of the appendices 1 to 5.

[0237] [Note 7] The type of frame is identified by the Trigger Type subfield in the Trigger frame, as described in Appendix 6 of the communication device.

[0238] [Note 8] The information relating to the DRU is included in the RU Allocation subfield of the Trigger frame as defined in the IEEE 802.11 standard series, as described in Appendix 4 or 5 of the communication device.

[0239] [Note 9] The communication device as described in Appendix 5, wherein the frame includes an individual AP information field for each AP, and the information regarding the DRU is included in the AP information field corresponding to the other APs.

[0240] [Note 10] A communication method performed by a communication device that functions as an AP as defined in the IEEE 802.11 standard series, The process of sending a frame to a communication device belonging to a BSS managed by another AP, requesting that the other AP perform data transmission using C-OFDMA with DRU. A communication method that includes this.

[0241] [Note 11] A program to cause a computer to execute the communication method described in Appendix 10. [Explanation of Symbols]

[0242] 100, 120 Wireless LAN 101, 121 AP 102, 103, 122, 123 STA 201 Storage section 202 Control Unit 203 Functional Section 206 Communications Department 207 Antenna 301 Ability information storage unit 302 DRU allocation section 303 Frame Generation and Analysis Unit 304 Frame Transmitter / Receiver

Claims

1. A communication device that functions as an Access Point (AP) as defined in the IEEE 802.11 standard series, A transmission means that transmits a frame requesting the other AP to perform data transmission using Coordinated Orthogonal Frequency Division Multiple Access (C-OFDMA) with a Distributed Tone Resource Unit (DRU) when a communication device belonging to a Basic Service Set (BSS) managed by another AP is performed. A communication device equipped with the following features.

2. The communication device according to claim 1, wherein the communication device belonging to the BSS is the other AP.

3. The communication device according to claim 1, wherein the communication device belonging to the BSS is a non-AP Station (non-AP STA) as defined in the IEEE 802.11 standard series.

4. The communication device according to claim 1, wherein the frame includes information relating to a DRU assigned to a non-AP STA belonging to the BSS.

5. The communication device according to claim 1, wherein the frame includes information relating to a DRU that the other AP can assign to a non-AP STA belonging to the BSS.

6. The communication device according to claim 1, wherein the frame is a type of Trigger frame as defined in the IEEE 802.11 standard series.

7. The type of the frame is identified by the Trigger Type subfield in the Trigger frame, according to claim 6.

8. The communication device according to claim 4 or 5, wherein the information relating to the DRU is included in the RU Allocation subfield of the Trigger frame as defined in the IEEE 802.11 standard series.

9. The communication device according to claim 5, wherein the frame includes an individual AP information field for each AP, and the information relating to the DRU is included in the AP information field corresponding to the other APs.

10. A communication method performed by a communication device that functions as an AP as defined in the IEEE 802.11 standard series, The process of sending a frame to a communication device belonging to a BSS managed by another AP, requesting that the other AP perform data transmission using C-OFDMA with DRU. A communication method that includes this.

11. A program for causing a computer to execute the communication method described in claim 10.

Images