Access point, method for controlling access point, and program

Abstract

This access point allocates a portion of a band for which a transmission opportunity has been acquired to another access point, and transmits a frame including information relating to the allocated first band to the other access point. Then, in a primary channel, a response frame to the aforementioned frame is received, the response frame including information relating to the first band that was allocated to the other access point.

Description

Access Point, Access Point Control Method, and Program

[0001] The present invention relates to communication means for access points and stations.

[0002] Communication standards for wireless LANs (Wireless Local Area Networks) have been established. In particular, the IEEE (Institute of Electrical and Electronics Engineers) 802.11 standard series is known as a wireless LAN standard. The IEEE 802.11 standard series includes standards such as IEEE 802.11a / b / g / n / ac / ax / be (Patent Document 1).

[0003] In the IEEE 802.11bn standard and its successor standards, studies have been conducted on improving communication efficiency and throughput by cooperatively operating a plurality of access point devices (hereinafter also simply referred to as APs). Communication technology in which a plurality of APs perform cooperative operation is called Multi-AP communication, and APs are classified into one Sharing AP that manages all APs, and Shared APs that operate under the management of the Sharing AP.

[0004] Japanese Patent Application Laid-Open No. 2018-50133

[0005] Incidentally, as an example of Multi-AP communication, studies have been conducted on sharing and allocating a part of TXOP (Transmission Opportunity) secured by one AP to another AP. A technology for improving efficiency called Coordinated TDMA (Time Division Multiple Access), in which a plurality of APs perform cooperative communication, is being studied.

[0006] However, when a plurality of APs perform the above-described cooperative communication, no mechanism has been defined for an AP to allocate frequencies used during transmission by another AP to said other AP.

[0007] The present invention has been made in view of the above-mentioned problems. One aspect of the present invention is to provide an AP mechanism for allocating frequencies to each AP when multiple APs perform cooperative communication.

[0008] To achieve the above objective, an access point as one aspect of the present invention comprises: control means for allocating a first bandwidth, which is at least a portion of the bandwidth from which the access point has acquired a transmission opportunity, to another access point; transmission means for transmitting a frame containing information about the first bandwidth to the other access point; and receiving means for receiving a response frame to the frame on a primary channel, wherein the response frame received on the primary channel contains information about the first bandwidth allocated to the other access point.

[0009] According to one aspect of the present invention, when multiple APs perform cooperative communication, it becomes possible to assign a frequency to each AP.

[0010] A diagram showing an example configuration of the wireless communication system in this embodiment. A diagram showing an example of the functional configuration of the communication device in this embodiment. A diagram showing the hardware configuration of the communication device in this embodiment. A sequence diagram when an AP allocates a subband to another AP. An example of processing by a Sharing AP. An example of processing by a Shared AP. An example of processing by STA. A diagram showing the configuration of the Multi-STA Block Ack format. A diagram showing the configuration of the Extended CTS format.

[0011] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way.

[0012] (Network Configuration) Figure 1 shows an example of the network configuration related to this embodiment. This wireless communication system consists of two access point devices (hereinafter simply referred to as AP, AP STA, or access point) and six station devices (hereinafter simply referred to as STA, Non-AP STA, or station). Hereafter, AP110, AP120, STA111-113, and STA121-123 will be collectively referred to as communication device 100. Similarly, AP110 and AP120 will be collectively referred to as AP101, and STA111-113 will be collectively referred to as STA102.

[0013] AP101 is configured to enable wireless transmission of frames compliant with the IEEE 802.11bn standard, which aims for a maximum transmission speed of over 90-100 Gbps. STA102 is similarly configured to enable wireless transmission of frames compliant with the IEEE 802.11bn standard. In this specification, frames transmitted wirelessly are referred to as wireless frames.

[0014] IEEE stands for Institute of Electrical and Electronics Engineers. 802.11bn is characterized by its support for high reliability, low latency communication, and AP coordination. Based on the above, in this embodiment, the wireless frame communicated using this standard is also referred to as UHR PPDU (Ultra High Reliability PLCP Protocol Data Unit). PLCP stands for Physical Layer Convergence Protocol.

[0015] It should be noted that the names IEEE 802.11bn and UHR standards were established for convenience, taking into account the goals to be achieved in successor standards and the characteristics of those standards, and may be given different names once the standards have been finalized. On the other hand, it should be noted that this specification and the attached claims are essentially successor standards to the 802.11be standard and are applicable to all successor standards that can support the function of performing Coordinated TDMA communication in which multiple APs communicate in a subband.

[0016] Note that Figure 1 shows a wireless communication network including two APs and six STAs as an example, but the number of these devices may be more or less than shown. In addition, although the communication device 100 is said to support UHR PPDU communication (transmission and reception), it can also be configured to support legacy PPDU communication, which is a standard prior to the IEEE 802.11bn standard. Specifically, the communication device 100 can also be configured to support the transmission and reception of PPDUs such as the IEEE 802.11a / b / g / n / ac / ax / be standards.

[0017] AP101 is an AP that operates in cooperation with multiple APs, and AP120 is an AP that performs overall control for cooperation. In this embodiment, an AP like AP120 that performs overall control is also called a Sharing AP. AP110 is an AP that functions as a controlled device controlled by the Sharing AP. In this embodiment, an AP like AP110 that is controlled by the Sharing AP is also called a Shared AP. The roles of the Sharing AP and the Shared AP may change dynamically. AP110 provides network 103, and AP120 provides network 104. STA102 is an STA that participates in the network provided by the access point.

[0018] In Figure 1, STAs 111-113 participate in network 103 provided by AP 110, and STAs 121-123 participate in network 104 provided by AP 120. AP 101 can perform MU (Multi-User) communication, which allows simultaneous communication with multiple STAs using OFDMA (Orthogonal Frequency Division Multiple Access) technology. In MU communication using OFDMA technology, one channel is divided into multiple subchannels called RUs (Resource Units). By treating each divided RU as a resource that communicates with a different STA (or a group of STAs composed of multiple STAs), it becomes possible for the AP and multiple STAs to communicate simultaneously on a single channel. In this case, an MU (Multi-User) PPDU with data modulated using OFDMA is transmitted from the AP to one or more STAs. If all devices comply with the IEEE 802.11bn standard, the AP shall transmit a UHR MU PPDU, which is an IEEE 802.11bn compliant MU PPDU, to one or more STAs.

[0019] Furthermore, STA111 and STA112 are within range of AP110's radio waves, but not within range of AP120's radio waves. STA121 and STA123 are within range of AP120's radio waves, but not within range of AP110's radio waves. STA122 and STA113 are within range of both AP110 and AP120's radio waves. AP110 and AP120 are either within range of each other's radio waves or can exchange information with each other via a wired connection. Note that "within range of radio waves" means that wireless communication is possible between APs and STAs, or between APs and APs.

[0020] Furthermore, the communication device 100 can also be configured to support wireless communication based on other communication standards such as Bluetooth®, NFC, and Bluetooth® LE (Low Energy). NFC stands for Near Field Communication. AP101 can also be configured to support wired communication using Ethernet® cables or wired communication using optical fibers. Specific examples of the communication device 100 include, but are not limited to, wireless LAN routers and personal computers (PCs). The communication device 100 may also be an information processing device such as a wireless chip that supports the transmission and reception of UHR PPDUs. Specific examples of STA102 include, but are not limited to, cameras, tablets, smartphones, PCs, mobile phones, video cameras, smart glasses and other wearable devices, and portable medical devices.

[0021] In this embodiment, when AP101 provides a network, each network's BSSID will be different. BSSID stands for Basic Service Set Identifier and is an identifier used to identify an access point.

[0022] Furthermore, each communication device, such as the communication device 100, can communicate using bandwidths of 20 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 480 MHz, and 640 MHz.

[0023] Next, we will explain the coordinated operation of multiple APs, including AP101, operating in coordination. AP101 can perform coordinated operation. Specifically, AP120 secures and shares a TXOP (Transmission Opportunity). A TXOP is a transmission opportunity. "Securing a TXOP" means obtaining an opportunity to transmit, that is, obtaining the right to transmit. In addition, AP120 allocates and shares a subband used by other APs for communication in the secured TXOP. This allows multiple APs, including AP101, to perform Coordinated TDMA communication, where they communicate at different times. Each AP can perform DL (Down Link) communication or UL (Up Link) communication with the STA connected to it in the TXOP assigned to it. In this embodiment, AP120 is a Sharing AP that allocates and shares a TXOP to other APs, but another AP that initially secures a TXOP may also be designated as a Sharing AP. In other words, the roles of Sharing AP and Shared AP may change dynamically. In this embodiment, there is one Shared AP for each Sharing AP. This is intended to simplify the procedures defined in IEEE 802.11. Simplifying the procedures makes it easier to implement AP120, which is a Sharing AP, and AP110, which is a Shared AP.

[0024] On the other hand, to allow for more flexible allocation, two or more Shared APs may be provided for each Sharing AP.

[0025] The mechanism for performing Coordinated TDMA communication will be described in detail below. In order to effectively explain the Coordinated TDMA function, AP101 in the wireless communication system of this embodiment will be described as providing a network that STAs can participate in using the same operating frequency band and bandwidth.

[0026] (Device Configuration) Figure 2 is a block diagram showing the functional configuration of the communication device 100. Here, the communication device 100 includes a wireless LAN control unit 201, a wireless frame generation unit 202, a wireless frame processing unit 203, a MAP control unit 204, and a subband allocation unit 205.

[0027] The wireless LAN control unit 201 includes an antenna and circuit for transmitting and receiving wireless signals with other communication devices, and a program to control them. The wireless LAN control unit 201 performs wireless LAN communication control based on frames generated by the frame generation unit in accordance with the IEEE 802.11 standard series. The wireless frame generation unit 202 generates frames to be transmitted by the wireless LAN control unit 201. The MAP control unit 204 controls the operation of the Multi-AP. The operation of the Multi-AP is the operation for cooperation between multiple APs. The MAP control unit 204 controls which APs can cooperate with and acquires and stores information on how much buffer capacity another AP has. If AP 120 is a Sharing AP, the subband allocation unit 205 of AP 120 determines the subbands to be allocated to AP 110 and AP 120 based on information for determining subbands obtained from the Shared AP AP 110. Furthermore, the subband allocation unit 205 of the Shared AP's AP110 determines the subband allocated to it according to the contents of the Trigger frame containing subband allocation information transmitted by the Sharing AP's AP120. It then uses that subband to communicate with the STA connected to it.

[0028] Figure 3 shows the hardware configuration of the communication device 100 according to this embodiment. AP and STA have, as an example of their hardware configuration, a storage unit 301, a control unit 302, a function unit 303, an input unit 304, an output unit 305, a communication unit 306, and an antenna 307.

[0029] The storage unit 301 is composed of one or more memories, such as ROM, RAM, or either one of them, and stores various information such as programs for performing various operations described later, and communication parameters for wireless communication. In addition to memories such as ROM and RAM, storage media such as flexible disks, hard disks, SSDs (Solid State Drives), optical disks, magneto-optical disks, CD-ROMs, CD-Rs, magnetic tapes, non-volatile memory cards, and DVDs may be used as the storage unit 301.

[0030] The control unit 302 is composed of, for example, one or more processors such as a CPU or MPU, an ASIC (Application-Specific Integrated Circuit), a DSP (Digital Signal Processor), or an FPGA (Field-Programmable Gate Array). Here, CPU is an acronym for Central Processing Unit, and MPU is an acronym for Micro Processing Unit. The control unit 302 controls the entire device by executing a program stored in the storage unit 301. Alternatively, the control unit 302 may control the device in cooperation with the OS (Operating System) and the program stored in the storage unit 301. The control unit 302 also controls the function unit 303 to perform predetermined processes such as imaging, printing, and projection. The function unit 303 is hardware for the AP or STA to perform predetermined processes. For example, if the AP or STA is a camera, the function unit 303 is the imaging unit and performs imaging processing. Furthermore, for example, if AP or STA is a printer, the functional unit 303 is a printing unit and performs printing. Also, for example, if AP or STA is a projector, the functional unit 303 is a projection unit and performs projection. The data processed by the functional unit 303 may be data stored in the storage unit 301, or data communicated with other communication devices via the communication unit 306, which will be described later.

[0031] The input unit 304 receives various operations from the user. The output unit 305 provides various outputs to the user. Here, the output from the output unit 305 includes at least one of the following: display on the screen, audio output from a speaker, vibration output, etc. Note that both the input unit 304 and the output unit 305 may be implemented in a single module, such as a touch panel. Furthermore, the input unit 304 and the output unit 305 may be integrated with the AP or STA, respectively, or they may be separate components.

[0032] The communication unit 306 is configured to include a so-called wireless LAN chip (wireless LAN IC (integrated circuit)) and controls wireless communication in accordance with the IEEE 802.11 standard series and IP communication. In this embodiment, the communication unit 306 can perform processing in accordance with at least the IEEE 802.11bn standard. The communication unit 306 is a processing device that generates UHR PPDUs as defined in the IEEE 802.11bn standard, and may also have the function of generating PPDUs of types defined in earlier standards. The communication unit 306 also controls the antenna 307 to transmit and receive wireless signals for wireless communication.

[0033] AP and STA communicate content such as image data, document data, and video data with other communication devices via the communication unit 306. Antenna 307 may be composed of two or more physical antennas to realize MIMO (Multi-Input and Multi-Output) transmission and reception. Antenna 307 may be configured separately from the communication unit 306, or it may be configured as a single module together with the communication unit 306. Antenna 307 is an antenna capable of communication in the 2.4 GHz band, 5 GHz band, 6 GHz band, 45 GHz band, and 60 GHz band. In Figure 3, the communication device is shown to have one antenna, but the communication device may have two or more antennas, or it may have different antennas for each frequency band. In the example in Figure 3, the configuration is shown to have only one communication unit 306, but it is also possible to provide a separate communication unit for each of the multiple antennas.

[0034] AP101 can be any communication device having the configuration shown in Figures 2 and 3. It may be a so-called AP-dedicated communication device such as a wireless LAN router, or it may be a communication device with AP functionality such as a smartphone, camera, or printer.

[0035] (Processing Flow) Next, we will describe some embodiments, such as the processing flow performed by the AP and STA as described above, and the sequence in the wireless communication system.

[0036] Figure 4 is a sequence diagram showing an example of wireless frame exchange when AP120 and AP110 work together and AP120 assigns a subband to AP110, and each communicates with the connected STA.

[0037] AP110 and AP120 first negotiate to operate cooperatively as a Multi-AP (460, 461). The negotiation takes place using request frame 460 and response frame 461. At this time, request frame 460 may include the capability information of AP120. Similarly, response frame 461 may include the capability information of AP110. Here, capability information may indicate, for example, the maximum bandwidth that AP120 or AP110 can handle, or the extent to which AP120 or AP110 can change the primary channel. Alternatively, it may indicate the lowest MCS rate that AP120 or AP110 can transmit. Alternatively, AP120 or AP110 may provide information indicating the maximum padding length that can be assigned to the Multi-STA Block Ack (MBA410, MBA411, MBA412, MBA413) described later. The minimum rate MCS and padding length can be used when transmitting with MBA410, MBA411, MBA412, and MBA413 described later. Based on this information, AP120 and AP110 can determine, for example, whether they share the same bandwidth even if the primary channels are different. They can also determine whether they are in a state where they can cooperate as Multi-APs.

[0038] Alternatively, instead of request frame 460 and response frame 461, the above-mentioned Capability information may be communicated to each other via Beacon (450) or Probe Response (451). Alternatively, instead of request frame 460 and response frame 461, the above-mentioned Capability information may be communicated to each other via UHR Capabilities Element or UHR Operation Element.

[0039] Next, AP120 transmits MU-RTS (400) after carrier sense (401) to secure TXOP. By AP120 transmitting MU-RTS, TXOP for a predetermined period is secured. The MU-RTS includes information on the subbands that AP120 assigns to AP120 and AP110, respectively. In this embodiment, it is assumed that MU-RTS is transmitted with a bandwidth of 320 MHz. The secured 320 MHz is divided into 80 MHz subbands, which are designated as subbands 490, 491, 492, and 493 from lowest to highest frequency. In this embodiment, subband 490, which is the primary channel at 80 MHz, and subband 491, which is the secondary channel at 80 MHz, are assigned to AP120, while subband 492, which is the secondary channel at 160 MHz, is assigned to AP110.

[0040] AP120 transmits Multi-STA Block Ack (MBA410, MBA411) on both its primary channel, subband 490, which is allocated to AP120, and subband 491, which is also allocated to AP120. This allows surrounding STAs to be notified of the subband and subbandwidth that AP120 will use for communication. Note that the Multi-STA Block Ack may be transmitted by duplicating the same frame in 20MHz units.

[0041] When AP 110 receives the MU-RTS and confirms that subband 492 has been allocated by AP 120, it transmits Multi-STA Block Ack (MBA 412, MBA 413) on both subband 490, which is its own primary channel, and the allocated subband 492. In addition, AP 110 performs control to enable data frame transmission and reception on the allocated subband 492 (SW1).

[0042] MBA 412 and MBA 413 may be the same as the MBA transmitted by AP 120. STA 111 cannot receive the MU-RTS transmitted from AP 120. However, since STA 111 is connected to AP 110 via subband 490, it can recognize from MBA 412 received from AP 110 that AP 110, to which it is connected, has been allocated subband 492.

[0043] In addition, MBA 410 to 413 may be transmitted using the lowest rate MCS that can be transmitted by AP 101, which is exchanged during MAP negotiation or in Beacon frame 450 and Probe Response 451. This allows the PHY parameters transmitted in the MBA to be uniform.

[0044] In addition, MBA 410 to 413 may be transmitted with the maximum padding length that can be provided by the aforementioned AP 101. This allows the padding transmitted in the MBA to be uniform. By receiving MBA 412, STA 111 recognizes that the subband allocated to AP 110, which is the Shared AP, from AP 120, which is the Sharing AP, is subband 492. Then, STA 111 transitions the transmission / reception band to subband 492 so that data frame transmission and reception can be performed on the allocated subband (SW2).

[0045] Here, the subband that AP120, a sharing AP, assigns to AP110, a shared AP, is assumed to be greater than (wider than) 20 MHz. This is because the bandwidth unit for carrier sensing by AP110, a shared AP, is 20 MHz. Carrier sensing is a function in which a communication device attempting to transmit measures the power in the bandwidth it attempts to transmit in for a certain period of time and determines whether other communication devices are communicating in that bandwidth. If the measured power is below a predetermined value, it is determined that no other communication devices are communicating, and the communication device transmits. On the other hand, if the measured power is above a predetermined value, it is determined that other communication devices are communicating, and the communication device does not transmit. Therefore, if AP110 is assigned a subband smaller than 20 MHz, the bandwidth of the subband that AP110 transmits in (less than 20 MHz) and the bandwidth used for carrier sensing (20 MHz) do not match, resulting in a decrease in the accuracy of carrier sensing. Therefore, the subband that AP120, a sharing AP, assigns to AP110, a shared AP, is assumed to be greater than (wider than) 20 MHz. Alternatively, the subband that AP120, a sharing AP, assigns to AP110, a shared AP, is assumed to be a multiple of 20 MHz.

[0046] Furthermore, for example, RTS (Request-to-Send) and CTS (Clear-to-Send) signals use a bandwidth of 20 MHz or higher (a multiple of 20 MHz). However, if a subband smaller than 20 MHz is assigned to the AP110, the AP110 will no longer be able to transmit and receive RTS (Request-to-Send) and CTS (Clear-to-Send) signals with a bandwidth of 20 MHz or higher (a multiple of 20 MHz).

[0047] Furthermore, the Ack signal uses a bandwidth of 20 MHz or more (a multiple of 20 MHz). However, if a subband smaller than 20 MHz is allocated to AP 110, AP 110 will not be able to transmit and receive Ack with a bandwidth of 20 MHz or more (a multiple of 20 MHz). Therefore, the Sharing AP shall allocate to the Shared AP a bandwidth of 20 MHz or more (a multiple of 20 MHz). In addition, dRU (Distributed Resource Unit) is not used. A dRU is an RU having discontinuous bands that are greater than or equal to a predetermined bandwidth.

[0048] Furthermore, for smooth communication, subband allocation may not be performed at 2.4 GHz. This is because communication using 20 MHz is predominant in the 2.4 GHz band, and communication using 40 MHz is less frequent.

[0049] Note that the minimum unit of subbands allocated by the Sharing AP to the Shared AP may be 80 MHz. That is, the subband allocated by the Sharing AP to the Shared AP may be 80 MHz or more (a multiple of 80 MHz). This is because in the 6 GHz band, Trigger Frames are handled in units of 80 MHz, and the PHY preamble of the frame is also handled in units of 80 MHz. Furthermore, this is because when individual APs transmit and receive frames, there is no need to be aware of overlapping basic service sets (OBSS).

[0050] When the subband allocation process is completed, each AP communicates with the STAs connected to the corresponding AP according to the allocation.

[0051] AP110 transmits a Trigger Frame (TF420) to communicate with STA111. The Trigger Frame (TF420) contains information about the RU assigned by AP110 to STA111. Using the RU assigned to STA111 contained in TF420, STA111 transmits a PPDU 432. The PPDU 432 is transmitted as a response signal to the Trigger Frame (TF420). Subsequently, upon receiving the PPDU 432, AP110 transmits a Block Ack (BA442) to STA111 as an acknowledgment of receipt of the PPDU 432. All transmission and reception of TF420, PPDU 432, and BA442 are performed within the bandwidth of subband 492, which is allocated by the sharing AP AP120. Once the transmission and reception of data (TF420, PPDU432, BA442) is complete, AP110 and STA111 return the bandwidth used for transmitting and receiving data to the primary channel, subband 490 (SWB1). Meanwhile, AP120, a sharing AP, transmits a Trigger Frame (TF430) to communicate with STA122. The Trigger Frame (TF430) contains information about the RU assigned by AP120 to STA122. Using the RU assigned to STA122 contained in TF430, STA122 transmits a PPDU431. The PPDU431 is transmitted as a response signal to the Trigger Frame (TF430). Subsequently, upon receiving PPDU431, AP120 sends a Block Ack (BA441) to STA122 as an acknowledgment of receiving PPDU431. All transmissions and receptions of TF430, PPDU431, and BA441 are performed within the bandwidth of subband 490 and subband 491, which are allocated to AP120, the Sharing AP.

[0052] Here, STA121 does not support the IEEE 802.11bn standard, but rather the IEEE 802.11a / b / g / n / ac / ax / be standards, which were established before the IEEE 802.11bn standard. Because STA121 does not support the IEEE 802.11bn standard, it cannot understand MU-RTS. Therefore, the period from when AP120 transmits MU-RTS until the secured TXOP is completed is set to NAV (Network Allocation Vector). NAV is an indicator that shows the period during which transmission by STA has not started.

[0053] In the above, Figure 4 was used to illustrate an example of UL (Uplink) communication, where data is transmitted from STA to AP. However, the above configuration is not limited to this, and may also be applied to DL (Downlink) communication, where data is transmitted from AP to STA. In that case, TF420 in Figure 4 replaces the UHR PPDU of the data frame, and AP110 directly transmits the data to STA111. Alternatively, TF430 in Figure 4 replaces the UHR PPDU of the data frame, and AP120 directly transmits the data to STA122.

[0054] In Figure 4, AP110, a Shared AP, responds to AP120's MU-RTS400 with MBA412 and MBA413, but a different sequence may be used. For example, AP110 may respond to AP120's MU-RTS400 with CTS, and then respond with MBA412 and MBA413 after its SIFS (Short Interface Space). The CTS bandwidth should be in units of 20 MHz (20 MHz or more, multiples of 20 MHz). This sequence conforms to existing standards (standards prior to IEEE 802.11bn standards), and by applying the MU-RTS and CTS sequences already present in the standards to the above configuration, implementation can be simplified. Alternatively, the MU-RTS400 may use a BSRP (Buffer Status Report Pol) frame or a BSRP (Buffer Status Report Pol) trigger frame.

[0055] Figure 5 is a flowchart showing an example of the processing performed in AP120, which is a Sharing AP in this embodiment. This flowchart shows the processing performed when AP120, a Sharing AP, starts operating as an AP, including the subband allocation process for Shared APs and the processing performed when communication occurs.

[0056] The following details the processing of AP120, which is a Sharing AP, using Figure 5.

[0057] AP120, which is a sharing AP, checks whether it can cooperate with other APs and operate as a Multi-AP (S501). This corresponds to processes 460 and 461 in Figure 4 above. Then, it obtains information from AP110, which is a shared AP, regarding the amount of data that AP110 wants to send and receive (data queue, data buffer), or the required period for sending and receiving data (S502). This information may also be obtained during the sending and receiving of BSRP (Buffer Status Report Pol) frames and BSR (Buffer Status Report) frames performed by AP120 and AP110. Alternatively, the frames defined in IEEE 802.11ax may be extended for Multi-AP control and the information may be obtained by doing so.

[0058] AP120, a sharing AP, determines subband allocation using information collected from AP110, a shared AP (S503). This allocation may be switched depending on the width of the subbands available for transmission and reception between AP120 and AP110. For example, if a 320 MHz bandwidth is available, 160 MHz will be allocated to AP120 and 160 MHz to AP110. Alternatively, if a 160 MHz bandwidth is available, 80 MHz will be allocated to AP120 and 80 MHz to AP110.

[0059] In this way, candidate subbands to be assigned to each AP are determined in advance according to the bandwidth that can be secured. Then, based on the information of the candidate subbands to be assigned to each AP that were determined in advance, and the result of carrier sense (Figure 4 401) immediately before transmitting the MU-RTS frame, the bandwidth to be secured for transmission and reception of AP120 and AP110, and the subbands to be assigned to AP120 and AP110 respectively are finally determined. Next, based on the subband assignment result to AP120 and AP110 in S503, AP120 decides whether or not to assign a subband to another Shared AP (for example, AP110) (S504). If it decides not to assign a subband to another Shared AP (No in S504), AP120 transmits and receives data using the secured bandwidth, just like in a normal data transmission and reception flow (S509).

[0060] If AP 120 decides to allocate a subband to another Shared AP (e.g., AP 110) (Yes in S504), it sends an MU-RTS containing subband allocation information (S505). This corresponds to control 400 in Figure 4 described above. The MU-RTS includes information on which subband was allocated to each AP. The subband allocation information may be indicated using the AP ID included in the AID11 field 831 in Figure 8 described later. Including the AP ID of the Shared AP in the AID11 field 831 indicates that the AP corresponding to that AP ID has been allocated as a Shared AP. Next, AP 120 determines whether it has received a Multi-STA Block Ack (MBA) response from AP 110, the Shared AP to which it allocated the subband (S506). This is determined by whether or not it has received MBA 412 and MBA 413 in Figure 4 described above.

[0061] When AP120 receives a Multi-STA Block Ack (MBA412, MBA413) from AP110 (Yes in S506), AP120 transmits and receives data only on the subband assigned to it (S507). This corresponds to TF430, PPDU431, and BA441 in Figure 4 above.

[0062] If AP120 does not receive MBA412 or MBA413 from AP110 within a certain period of time, AP120 may transmit and receive data including the subband used by the MBA that was not received (S508). When AP120 transmits and receives using the subband used by the MBA that was not received, for example, TF430 transmits using both the subband that AP120 has assigned to itself and the subband from which it did not receive a response from the MBA (MBA412 and / or MBA413). In addition, AP120 may transmit and receive data on subbands that have not been assigned to it, assuming they are punctured.

[0063] After AP120 has finished sending and receiving data, it sends and receives an Ack (S510) and terminates the subband allocation process. After the subband allocation process is completed, processing may be resumed from S502 or S503.

[0064] Figure 6 is a flowchart illustrating an example of processing performed in AP110, which is a Shared AP in this embodiment. This flowchart shows the processing related to AP110 being allocated a subband from AP120, which is a Sharing AP, and the processing performed in the transmission and reception of data between AP110 and the STA connected to AP110. This flowchart shows the processing after AP110, which is a Shared AP, forms a group with AP120, which is a Sharing AP, for Multi-AP operation, and after AP120 and AP110 have exchanged information with each other.

[0065] AP110, which is a Shared AP, receives an MU-RTS from AP120, which is a Sharing AP, to perform C-TDMA (Coordinated Time Division Multiple Access) (S601). This corresponds to 400 in Figure 4 above. Next, AP110 determines whether or not its subband is allocated in the MU-RTS (S602). If the source of the MU-RTS is different from the Sharing AP that AP110 has decided to build a Multi-AP with, the process may proceed to S603. Here, the source of the MU-RTS is identified based on the Mac Address included in the MU-RTS. If MU-RTS does not have information indicating that a subband will be allocated to AP110 (No in S602), AP110 will set NAV until the end of the TXOP period indicated in MU-RTS (S603). At this time, there is a possibility that the TXOP may be interrupted midway, or that AP120 may reassign a TXOP or subband midway. Therefore, AP110 will not transmit frames during the TXOP period indicated in MU-RTS, but may monitor the channel.

[0066] Next, if AP110 determines that there is information in MU-RTS indicating that a subband should be assigned to AP110 (Yes in S602), it determines whether the assigned subband is currently in a busy state (S604).

[0067] For example, if another network (OBSS) is using the subband allocated to AP110, it is determined to be in a BUSY state (Yes in S604), and the process returns to S601.

[0068] Alternatively, you can proceed to S603 and configure the NAV settings until the TXOP allocated by OBSS is completed.

[0069] If AP110 determines that it is not in a BUSY state (No in S604), it transmits a Multi-STA Block Ack on both the primary channel set by AP110 and the subbands assigned to AP110 (S605). This corresponds to MBA412 and MBA413 in Figure 4 above. Note that if the bandwidth of the non-BUSY subbands among the subbands assigned to AP110 is 20 MHz or more in a continuous manner, and a portion of it is in a BUSY state, AP110 may puncture the bandwidth in the BUSY portion and respond with a Multi-STA Block Ack.

[0070] Then, AP110 sets the subband allocated to AP120 as the bandwidth in which AP110 will communicate. In other words, AP110 changes (moves) the bandwidth in which AP110 will communicate to the subband allocated to AP120 (S606).

[0071] Next, AP110 transmits and receives data using the assigned subband. AP110 determines whether or not to transmit a Trigger Frame (S607). For example, if AP110 transmits a MU-PPDU to one or more STAs connected to it, AP110 does not transmit a Trigger Frame. If AP110 determines not to transmit a Trigger Frame (Yes in S607), it transmits a PPDU (MU-PPDU) to the STAs connected to it (S613). Subsequently, it receives a Block Ack from the STA, which is a response to the transmitted PPDU (S614). The PPDU may be transmitted to only one STA, or it may be transmitted to multiple STAs using OFDMA or MU-MIMO.

[0072] If AP110 determines to transmit a Trigger Frame (Yes in S607), it transmits the Trigger Frame to the STA connected to AP110 (S608) and assigns a RU to that STA. The RU assigned at this time may be a dRU or an RRU (Regular Resource Unit). By assigning a dRU, the signal-to-noise ratio (SNR) is expected to improve, and the quality of data frames transmitted by multiple STAs can be enhanced. Therefore, in the operation of Multi-AP, by assigning RRUs to Shared APs (e.g., AP110) on a subband basis and applying dRU assignment to STAs, it is possible to improve the SNR while taking into consideration the communication of other networks (OBSS).

[0073] Here, the Trigger Frame transmitted by AP110 corresponds to 420 in Figure 4 above. After transmitting the Trigger Frame (S608), AP110 sets the reception parameters based on the status of the assigned RU (S609). Subsequently, it receives a TB PPDU (Trigger Based PPDU) from the STA connected to AP110 and demodulates the PPDU data (S610). Here, the TB PPDU transmitted from the STA corresponds, for example, to 432 in Figure 4 above. Once AP110 has successfully demodulated the data frame, it sends a Multi-STA Block Ack to the STA connected to AP110 (S611) to notify the STA that it has received the PPDU. In this case, Block Ack or Ack may be returned instead of Multi-STA Block Ack. Note that Multi-STA Block Ack corresponds to 442 in Figure 4 described above.

[0074] If AP110 confirms in S614 or S611 that data transmission and reception are complete, or if it determines by other means that communication on the subband has ended, AP110 terminates communication on the subband. Then, AP110 changes (moves) the bandwidth on which it communicates to the primary channel (490) (S612). This corresponds to SWB1 in Figure 4 above. Once back on the primary channel, the process returns to S601.

[0075] Figure 7 is a flowchart illustrating an example of the processing performed in the STA in this embodiment. This flowchart shows the processing performed when STA111 to STA113 transmit and receive data in accordance with resource allocation from AP120, which is a Sharing AP, and AP110, which is a Shared AP. The operation will be described below using the processing of STA111 as an example, but it can be applied to other STAs as well.

[0076] This flowchart shows the process after STA111 is connected to AP110. STA111 receives a Multi-STA Block Ack from AP110, which is a Shared AP (S701). This corresponds to MBA412 and MBA413 in Figure 4 above. Based on the information obtained from the Multi-STA Block Ack, STA111 recognizes the subband that AP120 has assigned to AP110 and changes (moves) the bandwidth in which STA111 will communicate to that subband (S702). This corresponds to SW2 in Figure 4 above. At this time, STA111 sets the communication parameters for communicating on the subband assigned to AP110.

[0077] Furthermore, if STA111 is able to receive and demodulate the MU-RTS transmitted by AP120, STA111 can recognize the subband to which AP110 has been assigned based on the information contained in AP120's MU-RTS. Therefore, STA111 may change (move) the bandwidth in which STA111 communicates to that subband based on the information contained in the MU-RTS. Also, if AP110 is not transmitting a Multi-STA Block Ack in the subband assigned to AP110, STA111 may change (move) the bandwidth in which STA111 communicates to the primary channel (S707).

[0078] When STA111 completes the change (move) of the communication band in S702, it determines whether or not it has received a Trigger Frame from AP110 to which it is connected (S703). If it has not received a Trigger Frame (No in S703), it determines whether or not it has received a PPDU as a data frame excluding the Trigger Frame (S708). If it has received a PPDU as a data frame, it responds by sending a Block Ack to AP110 (S709) and changes (moves) the band on which STA111 communicates to the primary channel (S707). If it has not received a PPDU (No in S708), it waits in a receiving state until a predetermined time measured by the timer has elapsed (No in S710). If it has not received a PPDU from AP110 even after the predetermined time has elapsed (Yes in S710), STA111 changes (moves) the band on which it communicates to the primary channel (S707). If a predetermined time has elapsed (Yes in S710), STA111 may set the NAV to the period of TXOP set for STA111 in MU-RTS, MBA412, or MBA413.

[0079] When STA111 receives a Trigger Frame (S703), it checks whether the Trigger Frame contains an AID indicating that STA111 is to be assigned to the RU (S704). If there is an AID indicating that STA111 is to be assigned to the RU, STA111 transmits a data frame using TB PPDU at that RU (S705). This corresponds to 432 in Figure 4 above as an example. Subsequently, STA111 receives a Multi-STA Block Ack from AP110 and confirms that AP110 has received the TB PPDU (S706). This Multi-STA Block Ack corresponds to 442 in Figure 4 above as an example.

[0080] Once STA111 confirms that AP110 has received the TB PPDU via a Block Ack or Multi-STA Block Ack transmitted by AP110, STA111 changes (moves) the bandwidth on which it communicates to the primary channel (S707). This corresponds to SWB1 in Figure 4 above, as an example.

[0081] After STA111 changes (moves) the primary channel (S707), it returns to S701.

[0082] If STA111 determines, after analyzing the Trigger Frame, that it has no RU allocation (No in S704), it changes (moves) the bandwidth on which STA111 communicates to the primary channel (S711). At this time, STA111 sets NAV until the period of TXOP secured by Multi-STA Block Ack (MBA412, MBA413) ends (S712). During the NAV period, power saving mode may be activated, and power consumption may be reduced by not receiving data.

[0083] Alternatively, if the TXOP secured by the Trigger Frame is shorter than the TXOP secured by the Multi-STA Block Ack, STA111 may continue in a receiving standby state on the subband.

[0084] Figure 8 shows examples of the frame configurations of MBA410, MBA411, MBA412, and MBA413 in Figure 4 of this embodiment. This frame format is based on the format specified in the IEEE 802.11 series standard. The specific configuration of the Multi-STA Block Ack frame format will be described below.

[0085] The Multi-STA Block Ack frame includes Frame Control field 801, Duration field 802, RA field 803, TA field 804, BAR Control field 805, BAR Information field 806, Padding field 807, and FCS field 808.

[0086] The Frame Control field 801 includes a Type subfield and a Subtype field indicating the frame type. STA indicates that the frame is a Block Ack frame by setting the Type subfield to "01" to indicate a Control frame and the Subtype subfield to "1001" to indicate a Block Ack. The Duration field 802, RA field 803, and TA field 804 conform to the contents of the MAC header of a Block Ack frame, which is a control frame as defined in the IEEE 802.11 standard. MAC stands for Medium Access Control. RA stands for Receiver Address, and the MAC address of the destination device is stored in the RA field. TA stands for Transmitter Address, and the TA field stores the MAC address of the source device. In Figure 4, for MBA410, MBA411, MBA412, and MBA413, the MAC address of AP120, a Sharing AP, is set in both the RA field and the TA field to ensure consistent field values. This prevents inconsistencies in content depending on the transmitting device and reduces the possibility of the receiving STA detecting it as noise. Alternatively, the TA field of MBA412 and MBA413 may include the MAC address of AP110, a Shared AP. This allows the source and destination to be indicated to surrounding STAs. In this case, AP120, a Sharing AP, may also have its address included in the TA field, and for MBA410 and MBA411, the address of AP110, a Shared AP, may also be included.

[0087] Next, the BAR Control field 805 is a field that indicates the type and policy of the Block Ack. It includes the BA Type subfield 811 and the TID_INFO subfield 813.

[0088] The BA Type subfield 811 can indicate the type of Block Ack. Setting the value of the BA Type subfield 811 to "11" in decimal indicates that the frame is a Multi-STA Block Ack. The TID_INFO subfield 813 will be Reserved in the case of a Multi-STA Block Ack.

[0089] The BAR Information field 806 contains different fields depending on the type of Block Ack. In the case of a Multi-STA Block Ack, it includes the Per AID TID Info field 814. The Per AID TID Info subfield is a subfield that can contain information for each AID and TID. The Per AID TID Info field 814 has a list structure that contains multiple 8-byte subfields, including the AID TID Info subfield 821.

[0090] The AID TID Info subfield 821 includes the AID11 subfield 831, the Ack Type subfield 832, and the TID subfield 833, and the meaning of the other fields differs depending on the value of the AID11 subfield 831. If the value of the AID11 subfield is the value assigned to the AP ID, then the Ack Type subfield 832 and the TID subfield 833 will be set to Reserved. Furthermore, the subfields that follow are interpreted as follows: Duration subfield 822 is 2 bytes, RU Allocation subfield 823 is 2 bytes, and the Reserved field is 2 bytes. Note that the contents of the list included in the Per AID TID Info field are just an example.

[0091] The AID11 subfield 831 indicates the AP ID that the Sharing AP assigns to the Shared AP. The AP ID uses the same field as the Association ID (AID) assigned to the connecting STA, and is identified as an AP ID if it exceeds a certain value. Alternatively, the same AID value may be used to recognize it as an AP ID when assigned to an AP, and as an AID when assigned to an STA.

[0092] The Duration subfield 822 indicates the length of the TXOP to be allocated. The unit is milliseconds. By providing the Duration field 822, the Duration allocated to each AP can be changed, but since it will have the same value as the Duration field 802, the Duration field 822 is not necessary. The RU Allocation subfield 823 indicates the allocation location of the subband. Examples of RU Allocation subfield 823 allocations are shown in Tables 1-1 to 1-3.

[0093]

[0094]

[0095]

[0096] The RU Allocation subfield 823 may be 4 bits, with a value of 1 indicating allocation in 80 MHz increments from the lowest frequency. This allows for flexible AP allocation in the smallest possible allocation units, and requires fewer fields. When assigning to AP110 in Figure 4, the value would be 0010. Alternatively, it may be 16 bits, allowing allocation in 20 MHz increments from the lowest frequency. In this case, it becomes possible to allocate subbands to the Shared AP AP110 with greater flexibility.

[0097] The padding field 807 is a field used to give the connected STA time to move to the subband. Padding is applied until sufficient time is secured for the STA to move to the subband.

[0098] FCS field 808 is a field used for error detection in received frames. FCS stands for Frame Check Sequence.

[0099] MBA410 and MBA411 may also transmit frames with extended CTS. An example of an extended CTS frame is shown in Figure 9.

[0100] The individual fields are the same as those shown in Figure 8, so their explanation is omitted. The value of the Subtype subfield included in the Frame Control field 801 is set to "1111". This allows for more concise notification of subband assignments to surrounding STAs. Note that the frame configuration is just an example; for example, the subband assignment may be indicated by a PHY Preamble. Alternatively, for example, the extended CTS may be indicated by transmitting a PHY Preamble via a UHR PPDU.

[0101] Through the series of processes described above, even in STAs where the Sharing AP's radio waves do not reach and only the Shared AP's radio waves reach, it becomes possible to move the bandwidth used for communication with the Shared AP to a subband, enabling data communication. Furthermore, the subband allocation for AP120 can be changed each time MU-RTS is transmitted, increasing the flexibility of the bandwidth used.

[0102] (Other Embodiments) In the embodiments described above, AP120, which is a Sharing AP, is assumed to transmit MU-RTS to initiate C-TDMA, but C-TDMA is just one example.

[0103] For example, it could be an MU-RTS or BSRP to initiate a combined behavior of TWT (Target Wake Time) and NPCA (Non-Primary Channel Access). Alternatively, it could be an MU-RTS or BSRP to initiate C-OFDMA.

[0104] Another possible embodiment is one in which the primary channels of the Sharing AP, AP120, and the Shared AP, AP110, are different. Alternatively, the primary channels may be different, but some bandwidths may overlap between the Sharing AP, AP120, and the Shared AP, AP110. For example, the Sharing AP, AP120, uses channels 1 to 61 in the 6GHz band, with a center frequency of channel 31, and its primary channel is channel 1. The Shared AP, AP110, uses channels 33 to 93 in the 6GHz band, with a center frequency of channel 63, and its primary channel is channel 33. In this case, the Sharing AP, AP120, and the Shared AP, AP110, do not have the same primary channels, but the 160MHz band from channels 33 to 61 overlaps.

[0105] In this case, the Sharing AP, AP120, transmits MU-RTS at 320 MHz, and channels 1 through 29 can be allocated to be used by the Sharing AP, AP120, while channels 33 through 61 can be allocated to the Shared AP, AP110. Furthermore, since channel 33 is the primary channel for the Shared AP, AP110, there is no need to change the primary channel for data transmission or reception. In this case, instead of transmitting MBA410, MBA411, MBA412, and MBA413 as shown in Figure 4, it is sufficient to transmit CTS. Also, a reply (MBA410) on the primary channel of the Sharing AP, AP120, is unnecessary. In addition, depending on the channel status, TXOP can be secured by transmitting MBA411 on channels 65 through 93, which are not allocated to the Sharing AP, AP120.

[0106] Thus, when allocating subbands in a Multi-AP, it becomes possible to allocate resources even between APs with different primary channels.

[0107] The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments 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. It can also be realized by a circuit (for example, an ASIC) that implements one or more functions.

[0108] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0109] This application claims priority based on Japanese Patent Application No. 2025-051945, filed on 26 March 2025, and all of its contents are incorporated herein by reference.

[0110] 103, 104 Network 110, 120 AP 111, 112, 113, 121, 122, 123 STA

Claims

1. An access point that performs wireless communication in accordance with the IEEE 802.11 series standard, comprising: control means for allocating a first band, which is at least a portion of the band over which the access point has acquired a transmission opportunity, to another access point; transmission means for transmitting a frame containing information about the first band to the other access point; and receiving means for receiving a response frame to the frame on a primary channel, wherein the response frame received on the primary channel contains information about the first band allocated to the other access point.

2. The access point according to claim 1, further comprising: receiving means for receiving a response frame for the frame in the first bandwidth.

3. The access point according to claim 1 or 2, wherein the control means further allocates a second bandwidth, which is at least a portion of the first bandwidth, to the access point.

4. The access point according to claim 3, wherein the transmitting means further transmits a frame containing information about the second bandwidth to other access points.

5. The access point according to any one of claims 1 to 4, characterized in that the response frame has padding for securing a predetermined time.

6. The access point according to claim 5, further characterized in that the transmitting means transmits information for determining the number of paddings to the other access point.

7. An access point control method for performing wireless communication in accordance with the IEEE 802.11 series standard, comprising: a first step of allocating a first band, which is at least a portion of the band over which the access point has acquired a transmission opportunity, to another access point; a second step of transmitting a frame containing information about the first band to the other access point; a third step of receiving a response frame for the frame on a primary channel; and the response frame received on the primary channel containing information about the first band allocated to the other access point.

8. A program for causing a computer to function as an access point as described in any one of claims 1 to 6.

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