Wireless communication device

Abstract

To provide a mechanism enabling an AP to which radio resources are allocated from another AP, and a non-AP STA under the AP to perform transmission within the allocated radio resources in a wireless communication system using CSMA / CA.SOLUTION: A wireless communication device according to an embodiment includes a memory and a processing unit connected to the memory. The wireless communication device belongs to a first wireless communication group. The processing unit stores first, second and third parameters in the memory. The processing unit updates the first parameter when a received packet is transmitted from a second wireless communication device in the first wireless communication group, updates the second parameter when the received packet is transmitted from a third wireless communication device in a second wireless communication group partly formed by any of other access points to be linked with an access point constituting part of the first wireless communication group, and updates the third parameter otherwise.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to carrier sense communication, and particularly to communication in which a plurality of access points cooperate.

Background Art

[0002] In a wireless LAN (Local Area Network) system, cooperative operation of a plurality of access points (also referred to as access points; APs, base stations) has been proposed. As an example, a method has been proposed in which, after an AP acquires the right to transmit, it divides and allocates the time and frequency, which are wireless resources during the transmission opportunity (TXOP), to a plurality of other APs. The concept of this method has been determined to be adopted in 802.11 Task Group (TG) be, which standardizes the next-generation high-speed wireless LAN standard.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0005] However, in a wireless communication system using CSMA / CA (carrier sense multiple access with collision avoidance), since a NAV (network allocation vector) is set for the purpose of protecting the TXOP (transmission opportunity), even if an attempt is made to simply implement the proposed method in a wireless communication system using CSMA / CA, there is no mechanism for an AP that has been allocated wireless resources from other APs and non-AP STAs (hereinafter simply referred to as STAs or terminals) under it to transmit within the allocated wireless resources.

[0006] An object of the present invention is to provide a mechanism for an AP that has been allocated wireless resources from other APs and non-AP STAs under it to transmit within the allocated wireless resources in a wireless communication system using CSMA / CA. [Means for Solving the Problems]

[0007] The wireless communication device according to the embodiment is It is accommodated in a first wireless communication group together with a first terminal. The first wireless communication group, together with a second wireless communication group that accommodates a second wireless communication device and a second terminal, constitutes an extended wireless communication group. The wireless communication device receives a first frame for allocating a partial period of a first available time of a communication medium acquired by the second wireless communication device to the wireless communication device, and when using the partial period of the first available time, transmits a second transmission frame including a first field including information representing the partial period to the first terminal. The first terminal generates information indicating that the communication medium is virtually busy during the partial period based on the information included in the first field. [Brief Description of the Drawings]

[0008]

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Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to the drawings. The following description exemplifies apparatuses and methods for embodying the technical idea of the embodiments. The technical idea of the embodiments is not limited to the structure, shape, arrangement, material, etc. of the components described below. Modifications that can be easily conceived by those skilled in the art are naturally included in the scope of the disclosure. For the sake of clarity in the description, in the drawings, the size, thickness, planar dimensions, shape, etc. of each element may be changed with respect to the actual implementation mode and represented schematically. In a plurality of drawings, there may be elements whose dimensional relationships and ratios to each other are different. In a plurality of drawings, corresponding elements may be given the same reference numerals and redundant descriptions may be omitted. In some cases, a plurality of names may be assigned to some elements, but these examples of names are merely illustrative and do not deny the assignment of other names to these elements. Also, it does not deny the assignment of other names to elements that do not have a plurality of names assigned. In the following description, "connection" may include not only direct connection but also connection via other elements.

[0010] IEEE Std 802.11-2020 and IEEE Std 802.11ax-2021, which are known as the standards documents for wireless local area network (LAN), and the Specification Framework Document for IEEE Std 802.11be, the next-generation wireless LAN standard, dated September 23, 2021, IEEE 802.11-20 / 1935r44, are hereby incorporated by reference in their entirety in this specification.

[0011] Hereinafter, this embodiment will be described in detail with reference to the drawings.

[0012] <BSS, infrastructure BSS, ESS> FIG. 1 shows an example of a wireless communication system according to the first embodiment. In the IEEE802.11 standard (including extended standards such as the aforementioned IEEE Std 802.11ax-2021; the same applies hereinafter), the minimum unit of a wireless communication group is a basic service set (BSS). A BSS has a BSS identifier (BSSID). For example, in a broadcast frame transmitted to all terminals within a BSS, the BSSID is placed in one of the address fields of the data frame to be transmitted. A terminal that receives a data frame determines whether the frame is for all terminals within the BSS to which the own terminal belongs based on the BSSID, and performs processing such as extracting the payload of the data frame when it corresponds.

[0013] In the IEEE802.11 standard, two types of BSS forms are defined. One is a form in which a base station (AP; access point) starts a BSS and terminals (STA; station) connect to it. This is called an infrastructure BSS. The other is a form in which there is no AP and only STAs constitute a BSS. This is called an independent BSS. In this embodiment, the BSS to be handled is an infrastructure BSS.

[0014] In an infrastructure BSS (hereinafter, this will be expressed as BSS unless otherwise specified for the purpose of particularly contrasting with an independent BSS), the MAC (medium access control) address of the AP becomes the BSSID. The AP is a type of STA, and in this specification, both may sometimes be referred to as wireless communication devices. The AP has a function that enables the transfer of data from another STA that is the source of the data to another STA that is the destination of the data. The STA does not have this function. In this case, one of the other STA or another STA does not necessarily have to be in the same BSS as the AP, and they may be connected via another AP, or may be connected to a wired LAN.

[0015] A system for connecting an AP to other APs is called a distribution system (DS). Multiple APs may be connected to the DS, and the multiple APs connected by this DS constitute an extended service set (ESS). The identifier for identifying that they are the same ESS is the service set identifier (SSID).

[0016] In FIG. 1, as APs, AP1 and AP2 exist. AP1 accommodates STA11 and STA12 to constitute BSS1. AP2 accommodates STA21 and STA22 to constitute BSS2. BSS1 and BSS2 constitute an ESS.

[0017] <Wireless communication device> FIG. 2 shows an example of a wireless communication device according to the first embodiment. The wireless communication device includes an upper processing unit 10, a MAC processing unit 20, a PHY (Physical) processing unit 30, a MAC / PHY management unit 40, an analog processing unit 50, and an antenna 60. In FIG. 2, the number of analog processing units 50 and the number of antennas 60 are each one, but a plurality of analog processing units 50 and a plurality of antennas 60 may be provided for multiplexed communication. The number of the plurality of analog processing units 50 and the number of the plurality of antennas 60 may be equal or different. For example, two or more antennas 60 may be commonly connected to one analog processing unit 50.

[0018] The MAC processing unit 20, the MAC / PHY management unit 40, and the PHY processing unit 30 correspond to a form of a control unit or a baseband integrated circuit that performs processing related to communication with other wireless communication devices. The analog processing unit 50 corresponds to a form of a wireless communication unit or an RF (Radio Frequency) integrated circuit that transmits and receives signals via, for example, the antenna 60. The integrated circuit for wireless communication according to the present embodiment includes at least the former of the baseband integrated circuit and the RF integrated circuit. The functions of the baseband integrated circuit may be performed by software (program) operating on a processor such as a CPU, may be performed by hardware, or may be performed by both software and hardware. The software may be stored in a storage medium such as a memory such as ROM and RAM, a hard disk, or an SSD, and read and executed by the processor. The memory may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

[0019] The upper processing unit 10 performs processing for the upper layer with respect to the MAC layer. The upper processing unit 10 can exchange signals with the MAC processing unit 20. Examples of the upper layer include, but are not limited to, the TCP / IP layer, the UDP / IP layer, and the application layer above them. The upper processing unit 10 may include a buffer for exchanging data between the MAC layer and the upper layer. The wireless communication device may be connected to a wired infrastructure via the upper processing unit 10.

[0020] The MAC processing unit 20 performs processing for the MAC layer. As described above, the MAC processing unit 20 can exchange signals with the upper processing unit 10. Furthermore, the MAC processing unit 20 can exchange signals with the PHY processing unit 30. The MAC processing unit 20 includes a MAC common processing unit 70, a transmission processing unit 80, a reception processing unit 90, and a memory 94. The memory 94 is connected to the MAC common processing unit 70, the transmission processing unit 80, and the reception processing unit 90. The memory 94 stores data necessary for the processing of the MAC common processing unit 70, the transmission processing unit 80, and the reception processing unit 90. When the functions of the MAC processing unit 20 are performed by software, the memory 94 also stores the software of the MAC processing unit 20.

[0021] The MAC common processing unit 70 performs processing common to transmission and reception in the MAC layer. The MAC common processing unit 70 is connected to the upper processing unit 10, the transmission processing unit 80, the reception processing unit 90, and the MAC / PHY management unit 40, respectively, and exchanges signals with each of them.

[0022] The transmission processing unit 80 and the reception processing unit 90 are connected to each other. The transmission processing unit 80 is connected to the MAC common processing unit 70 and the PHY processing unit 30, respectively. The reception processing unit 90 is connected to the MAC common processing unit 70 and the PHY processing unit 30, respectively. The transmission processing unit 80 performs transmission processing in the MAC layer. The reception processing unit 90 performs reception processing in the MAC layer.

[0023] The PHY processing unit 30 performs processing for the PHY layer. As described above, the PHY processing unit 30 can exchange signals with the MAC processing unit 20. The PHY processing unit 30 is connected to the antenna 60 via the analog processing unit 50.

[0024] The MAC / PHY management unit 40 is connected to the upper processing unit 10, the MAC processing unit 20 (more specifically, the MAC common processing unit 70), and the PHY processing unit 30, respectively. The MAC / PHY management unit 40 manages the MAC operation and the PHY operation in the wireless communication device.

[0025] The analog processing unit 50 includes an analog / digital and digital / analog (AD / DA) converter and an RF circuit, converts the digital signal from the PHY processing unit 30 into an analog signal of a desired frequency for transmission from the antenna 60, and converts the high-frequency analog signal received from the antenna 60 into a digital signal. Here, although the AD / DA conversion is performed by the analog processing unit 50, a configuration in which the PHY processing unit 30 has an AD / DA conversion function is also possible.

[0026] The wireless communication device according to this embodiment includes (integrates) the antenna 60 as a component within one chip, thereby suppressing the mounting area of this antenna 60 to be small.

[0027] When transmitting a signal to the wireless medium, the PHY processing unit 30 receives a MAC frame from the transmission processing unit 80. The PHY processing unit 30 performs processing such as adding a preamble and a PHY header, encoding, and modulation to the MAC frame to convert it into a PHY packet. The analog processing unit 50 converts the PHY packet, which is a digital signal, into an analog signal of a desired frequency. The antenna 60 radiates the analog signal from the analog processing unit 50 to the wireless medium. Note that the PHY processing unit 30 outputs a signal indicating that the wireless medium is busy to the MAC processing unit 20 (more precisely, the reception processing unit 90) during the period of signal transmission.

[0028] The PHY processing unit 30 may perform processing related to at least one of uplink multi-user MIMO (UL-MU-MIMO) and downlink multi-user MIMO (DL-MU-MIMO) that extends MIMO technology. In UL-MU-MIMO, the AP simultaneously receives streams transmitted in spatial multiplexing (simultaneously in the same frequency band) from a plurality of STAs with a plurality of antennas, and demodulates the received signal by MIMO to separate it into frames for each STA. Thereby, the AP can receive frames transmitted simultaneously from a plurality of STAs in the same frequency band. In DL-MU-MIMO, the AP transmits streams in spatial multiplexing from a plurality of antennas to a plurality of STAs respectively, and each STA demodulates the received signal by MIMO to separate it into frames and receives the frame addressed to its own STA. Thereby, the AP can transmit frames to a plurality of STAs simultaneously in the same frequency band respectively.

[0029] When receiving a signal from the wireless medium, the analog processing unit 50 converts the analog signal received by the antenna 60 into a baseband signal processable by the PHY processing unit 30 and further converts it into a digital signal. The PHY processing unit 30 receives the digital received signal from the analog processing unit 50 and detects its received level. The detected received level is compared with the carrier sense level (threshold), and if the received level is equal to or higher than the carrier sense level, the PHY processing unit 30 outputs a signal indicating that the medium (CCA; clear channel assessment) is busy to the MAC processing unit 20 (more precisely, the reception processing unit 90). If the received level is lower than the carrier sense level, the PHY processing unit 30 outputs a signal indicating that the medium (CCA) is idle to the MAC processing unit 20 (more precisely, the reception processing unit 90).

[0030] The PHY processing unit 30 performs demodulation processing, processing to remove the preamble and PHY header, etc. on the received signal, and extracts the payload. In the IEEE 802.11 standard, this payload is called PSDU (physical layer convergence procedure (PLCP) service data unit) on the PHY side. The PHY processing unit 30 passes the extracted payload to the reception processing unit 90, and the reception processing unit 90 treats this as a MAC frame. In the IEEE 802.11 standard, this MAC frame is called MPDU (medium access control (MAC) protocol data unit). In addition, when the PHY processing unit 30 starts receiving a received signal, it notifies the reception processing unit 90 to that effect, and when it finishes receiving the received signal, it notifies the reception processing unit 90 to that effect. Also, when the received signal can be normally decoded as a PHY packet (if no error is detected), the PHY processing unit 30 notifies the reception processing unit 90 of the end of reception of the received signal, and passes a signal indicating that the medium is idle to the reception processing unit 90. When the PHY processing unit 30 detects an error in the received signal, it notifies the reception processing unit 90 that an error has been detected with an appropriate error code corresponding to the error type. Also, when the PHY processing unit 30 determines that the medium has become idle, it notifies the reception processing unit 90 of a signal indicating that the medium is idle.

[0031] The MAC common processing unit 70 mediates the transfer of transmission data from the upper processing unit 10 to the transmission processing unit 80 and the transfer of received data from the reception processing unit 90 to the upper processing unit 10, respectively. In the IEEE 802.11 standard, the data in this MAC data frame is called MSDU (medium access control (MAC) service data unit). Also, the MAC common processing unit 70 once receives an instruction from the MAC / PHY management unit 40, converts the instruction into a form suitable for the transmission processing unit 80 and the reception processing unit 90, and outputs it.

[0032] The MAC / PHY management unit 40 corresponds to, for example, the SME (station management entity) in the IEEE802.11 standard. In that case, the interface between the MAC / PHY management unit 40 and the MAC common processing unit 70 corresponds to the MLMESAP (MAC sublayer managament entity service access point) in the IEEE802.11 standard. The interface between the MAC / PHY management unit 40 and the PHY processing unit 30 corresponds to the PLMESAP (physical layer management entity service access point) in the IEEE802.11 wireless LAN.

[0033] In addition, in FIG. 2, the MAC / PHY management unit 40 is depicted as if the functional unit for MAC management and the functional unit for PHY management are integrated, but they may be implemented separately.

[0034] <Connection method to BSS and start of data frame exchange> When the AP starts up the BSS, it periodically transmits Beacon frames. In practice, since the Beacon frames are transmitted using CSMA / CA (carrier sense multiple access with carrier avoidance), the intervals are not strictly fixed.

[0035] The Beacon frame notifies the attributes of the BSS, the wireless communication capabilities of the AP, and the transmission time (timestamp) information for the STA to synchronize, and it is a broadcast frame. A broadcast frame is one in which all fields specifying the direct destination address (RA; receiver address) are set to 1. In the 802.11 standard, the RA is the first address field set when there are multiple address fields. The SSID may or may not be included in the Beacon frame. The transmission form without including the SSID is called the stealth mode.

[0036] When the AP receives a Probe Request frame from the STA, it sends a Probe Response frame to the STA. The Probe Request frame is usually sent as a broadcast frame. The Probe Response frame basically notifies the same information as the Beacon frame and is a unicast frame. A unicast frame is a frame in which the MAC address of a specific STA is specified for the RA. It is also possible for the STA to request more detailed information in the Probe Request frame. In that case, the AP adds the information requested in the Probe Request frame in addition to the same information as the Beacon frame and sends it. For example, when the STA specifies an element ID that it additionally requests in the Probe Request frame (request using the 9.4.2.10 Extended Request element in IEEE Std 802.11-2020), the AP adds the requested information to the Probe Response frame and sends it. Alternatively, when the STA includes a unique request that is communicated between the same vendors in the Probe Request frame (9.4.2.218 Vendor Specific Request element in IEEE Std 802.11-2020), the AP may put the requested information in the Probe Response frame and send it. Also, the STA can put a specific SSID in the Probe Request frame. In that case, among the multiple APs that received the Probe Request frame, the AP with the matching SSID sends a Probe Response frame. The STA sends a Probe Request frame specifying the SSID based on the user's input information. Therefore, if it is a stealth-mode AP and the STA is within an area where an AP with a matching SSID can receive the Probe Request frame, the STA can detect that AP.

[0037] By receiving a Beacon frame or a Probe Response frame, the STA grasps the APs to which the STA can connect. When there are multiple candidate APs for connection, the STA selects one of them and attempts to connect.

[0038] In the IEEE 802.11 standard, in order for a STA to connect to an AP and be able to exchange data frames with the AP, it is necessary to go through an authentication process and an association process.

[0039] In the authentication process, authentication frames are exchanged between the STA and the AP two or four times. The authentication process is initiated when the STA sends an authentication frame to the AP. The authentication frame is a unicast frame. The receiving side of the authentication frame sends an Ack frame. Subsequently, when the receiving side sends an authentication frame, the receiving side reacquires the access right and then sends the authentication frame. The case of four exchanges is when using WEP (Wired Equivalent Privacy). However, due to its vulnerability, WEP is not being used, so it usually completes with two transmissions from the STA to the AP and from the AP to the STA, and usually there is no four - time exchange. The authentication frame from the AP to the STA contains a Status Code field. The status code notifies the STA whether the AP accepts the request from the STA. When the AP accepts the request, it puts 0, which means SUCCESS, in the Status Code field. When the AP does not accept the request, it can notify the STA of the reason for non - acceptance by putting a value other than 0 in the Status Code field. As a value other than 0, for example, 1 is used when rejecting without specifying a particular reason, and 13 is used when rejecting on the grounds that the STA does not support the specific authentication algorithm specified by the AP.

[0040] That is, when the authentication process started from the STA ends successfully, that is, when the AP puts 0 in the Status Code field in the authentication frame, the STA then starts the association process. The association process is started when the STA sends an Association Request frame to the AP. The STA can store its own wireless communication capabilities in the Association Request frame and send it to notify the AP of its capabilities. Both the Association Request frame and the Association Response frame are unicast frames, and the receiving side sends an Ack frame for each. When the AP receives an Association Request frame from the STA, it sends an Association Response frame to the STA. The Association Response frame contains the Status Code field along with the AP's wireless communication capability information. When the Status Code field is 0 (SUCCESS), that is, in the Association Response frame notifying that the association request is accepted, an association identifier (AID), which is an identifier for identifying the STA within the BSS, is included. The AP assigns an AID to each STA. The STA assigned an AID has completed the connection with the AP and can exchange data frames with the AP. When the STA is in a connected state with the AP, the AID of the STA is valid. The field for notifying the AID is the AID field, which is composed of 16 bits. The actually valid value range as the AID is from 1 to 2007. When the AP sends a frame with the AID field filled in other than in the association process, values other than 1 to 2007 may be used for the AID field. In that case, the AID field is used to specify the attributes of the target STA, etc.

[0041] When the STA sends an association request frame in the reassociation process to reconnect from one AP to another AP, the same information exchange is performed in the same procedure as the association process. The difference between the reassociation process and the association process is that in the reassociation process, when the STA sends a reassociation request frame to another AP that it requests to reconnect to, the MAC address of the currently connected AP is added to the reassociation request frame. The other AP sends a Reassociation Response frame, which is a response to the reassociation request frame.

[0042] When the STA becomes capable of exchanging data frames with the AP, it can connect to the authentication server via the AP, and thus can perform encryption processing such as advanced security standard (AES) on the frames transmitted via the 4-way handshake procedure.

[0043] <MAC Frame> A MAC frame is a frame generated at the MAC layer. MAC frames are basically classified into three types: management frames, data frames, and control frames. In addition, some IEEE 802.11 extension standards also define extension frames.

[0044] The above-mentioned beacon frames, probe request frames, probe response frames, authentication frames, association request frames, association response frames, reassociation request frames, reassociation response frames, etc. are classified as management frames among MAC frames. Management frames are used for the management of communication links with other STAs.

[0045] The above data frame is classified as a data frame among MAC frames. The above data frame is further classified in detail according to whether it supports QoS (Quality of Service), whether it stores only data, or whether it contains additional information such as the meaning of the Ack frame. Note that a data frame usually stores data passed from the upper layer. However, as a special example, a data frame includes a data frame generated at the MAC layer and not containing data. There are two types of data frames not containing data: Null frames and QoS Null frames.

[0046] The above Ack frame is classified as a control frame among MAC frames. Other response control frames include BlockAck frames, BlockAckReq frames that request the transmission of BlockAck frames, RTS (Request to Send) frames transmitted at the beginning of frame exchange to acquire the transmission right to reduce retransmission damage, and CTS (Clear to Send) frames transmitted at the beginning of frame exchange to acquire the transmission right when not requesting a response to the RTS frame or when requesting a response from the transmission destination. Control frames are used for the control when transmitting and receiving (i.e., exchanging) management frames and data frames with other wireless communication devices.

[0047] <MAC Frame Format> Figure 3(a) is a diagram showing the basic format of a MAC frame. The management frame, data frame, and control frame according to this embodiment are based on such a frame format. This frame format includes fields of a MAC header, a Frame Body (variable length in octets), and an FCS (Frame Check Sequence) (4 octets). Note that there may also be MAC frames without a Frame Body field, such as Null frames and QoS Null frames, which are data frames not containing the above-mentioned data.

[0048] Figure 3(b) shows the basic format of the MAC header. The MAC header includes fields such as Frame Control (2 octets), Duration / ID (2 octets), Address 1 (6 octets), Address 2 (0 or 6 octets), Address 3 (0 or 6 octets), Sequence Control (0 or 2 octets), Address 4 (0 or 6 octets), QoS Control (0 or 2 octets), and HT (High Throughput) Control (0 or 4 octets).

[0049] Not all of these fields necessarily need to exist, and there can be MAC headers without some of the fields. For example, there are MAC headers without the Address 3 field or the Address 4 field. Also, there are MAC headers without both or either of the two fields QoS Control and HT Control. Additionally, other fields not shown in Figure 3 may be newly added to the MAC header.

[0050] The Frame Control field includes two fields such as Type and Subtype. The broad classification, such as whether it is a management frame, a data frame, or a control frame, is done by the Type field. The detailed classification within the broad classification of frames is done by the Subtype field. For example, for control frames, as described above, information such as the resolution of BlockAck frames, BlockAckReq frames, RTS frames, and CTS frames is put into the Subtype field.

[0051] The media reservation time is placed in the Duration / ID field. If the media reservation time is placed in the Duration / ID field and a STA other than the STA specified by the RA receives the frame, the receiving STA uses the Duration / ID field as the time (NAV value) for setting the NAV (network allocation vector) described below. In the PS (power save)-Poll frame used during power saving among control frames, instead of the media reservation time, the AID assigned to the STA that transmits the frame from the AP is described in the Duration / ID field. If a STA other than the STA specified by the RA receives the PS-Poll frame, the receiving STA grasps that the NAV value cannot be set from the Duration / ID field by grasping that the Type field represents a control frame and the Subtype field is a PS-Poll frame. In that case, the STA sets as the NAV value the sum of a fixed time called the short interframe space (SIFS) and the estimated time that the Ack frame transmitted as a response to the PS-Poll frame occupies the medium. The STA obtains the estimated time that this Ack frame occupies the medium from the transmission rate of the Ack frame estimated from the transmission rate of the PS-Poll frame and the Ack frame length (fixed at 14 octets).

[0052] The Receiver Address (RA) is placed in the Address 1 field. The Address 2 field may not exist in some control frames. If it exists, the Transmitter Address (TA) is placed in the Address 2 field. The Address 3 field does not exist in control frames. The Address 3 field exists in management frames and data frames. In the Address 3 field, depending on the use of the frame, the BSSID which is the identifier of the BSS, the TA, the Destination Address (DA) of the data, or the Source Address (SA) of the data is placed. Note that the BSSID may be a wildcard BSSID (all bits are 1) targeting all BSSIDs. The Address 4 field exists in the case of a data frame and when transferring data from the STA between APs. The Address 4 field is used for the Address 3 field to notify the DA. The Address 4 field is used to notify the SA.

[0053] The Sequence Control field is divided into a Sequence Number subfield and a Fragment Number subfield. The Sequence Number subfield contains the sequence number assigned to the frame, and the Fragment Number subfield contains the corresponding fragment number for the frame when the data is divided into multiple fragments by fragmentation.

[0054] The QoS field is used to perform QoS control for transmission considering the priority of the frame. The HT Control field is a field introduced in the IEEE802.11n standard and is also used in the IEEE802.11ac standard and the IEEE802.11ax standard, which are successors to the IEEE802.11n standard. When corresponding to the IEEE802.11n standard, an HT variant is provided in the HT Control field. When corresponding to the IEEE802.11ac standard, a VHT variant is provided. When corresponding to the IEEE802.11ax standard, a HE variant is provided. Each variant is identified by the first 1 bit or 2 bits of the HT Control.

[0055] The Frame Body field is a field for storing information according to the type and subtype of the frame. In data frames other than Null frames and QoS Null frames, data is stored in the Frame Body field. In management frames, multiple fixed fields and multiple information elements are stored in the Frame Body field according to the subtype. In control frames, there may be no Frame Body field according to the subtype, or multiple fixed fields may be included in the Frame Body field.

[0056] In the FCS field, FCS information is set as a checksum code used for error detection of the frame on the receiving side. Examples of FCS information include CRC (cyclic redundancy code).

[0057] <Explanation of NAV> In the IEEE 802.11 standard, after a STA (including an AP) acquires the media access right (hereinafter referred to as the transmission right) by CSMA / CA, when it obtains a transmission opportunity (TXOP), which is the time during which it can occupy the media, although it is subject to restrictions such as QoS (quality of service) attributes, it can continuously exchange MAC frames with other STAs (including APs).

[0058] In this TXOP, if a third-party STA other than the two STAs exchanging MAC frames transmits another MAC frame, the frame being exchanged between the two STAs (strictly speaking, the physical protocol data unit (PPDU) storing the frame) and the MAC frame transmitted by the third-party STA will collide. Therefore, a mechanism called NAV is provided to delay the acquisition of the transmission right by the third-party STA until after the end of the TXOP. In the state where NAV is set for third-party STAs around the two STAs exchanging MAC frames, the TXOP, that is, the radio resources are protected.

[0059] The receiving processing unit 90 first checks whether the medium is idle in the CSMA / CA process, that is, it performs carrier sensing. Here, the carrier sensing includes both a physical carrier sense regarding the busy / idle of CCA (clear channel assessment) and a virtual carrier sense based on the value of the Duration / ID field of the received frame or the received frame type. The physical carrier sense is activated when a signal of -62 dBm or more is detected on the physical medium. As in the latter case, the mechanism for virtually determining that the medium is busy, or the period for virtually setting the medium as busy, is called NAV. In the case where one channel is divided into a plurality of resource units (RUs) and transmission and reception are performed using a part of them, the receiving processing unit 90 may apply the result information of CCA performed in channel units or the carrier sense information based on NAV to the relevant part of the RUs. For example, for an RU belonging to a channel where the carrier sense information indicates idle, the receiving processing unit 90 determines that the carrier sense is idle. When a STA (including an AP) receives a MAC frame addressed to another STA, it sets the NAV from the end of the physical packet including the MAC frame. The receiving processing unit 90 can set the NAV by writing the NAV value into the memory 94. Also, when a new frame is received and the NAV set thereby is longer than the current NAV, that is, when the end timing of the NAV set by the new frame is later than the end timing set by the current NAV, the receiving processing unit 90 updates the current NAV value written in the memory 94 with the NAV value by the new frame. By this update of the NAV value, the end time of the current NAV is extended to the end time of the NAV by the new frame.

[0060] In the 802.11ax standard, the medium occupancy time indicated by the above Duration / ID field is also placed in the TXOP field of the HE-SIG-A field in the physical (PHY) header of the physical packet (HE PPDU) newly defined by the 802.11ax standard. When a STA (including an AP) receives a HE PPDU that cannot be received and decoded, and there is a significant value set in this TXOP field, it obtains the NAV value from that value. Also, there is a BSS Color field in the HE-SIG-A field of the HE PPDU. A STA (including an AP) can determine whether the HE PPDU is from within its own BSS or from a HE PPDU transmitted from another BSS (overlapping BSS; OBSS) based on this field. When a STA (including an AP) transmits a HE PPDU, it sets the BSS color value set in its own BSS in the BSS Color field. The BSS color value used in its own BSS is determined by the AP.

[0061] Furthermore, in the 802.11ax standard, in order to implement uplink (UL) multi-user (MU) transmission, an intra-BSS NAV is specially provided as the NAV applicable when the received physical packet is a physical packet transmitted from its own BSS. The intra-BSS NAV is distinguished from the NAV applicable in other cases, that is, the NAV applicable when the received physical packet is a physical packet transmitted from an OBSS or when the transmission source of the received physical packet cannot be determined whether it is the own BSS or the OBSS. Here, the NAV applicable in other cases is called the basic NAV. The frame for the AP to instruct UL MU transmission to one or more STAs is a Trigger frame. The Trigger frame is a type of control frame. FIG. 4 is a diagram showing whether UL MU transmission can be performed in response to the Trigger frame depending on the relationship between the setting state of the basic NAV and the setting state of the intra-BSS NAV. Strictly speaking, there is a CS Required subfield in the Trigger frame indicating whether carrier sense is required. When the subfield is "1", that is, when carrier sense is required, the STA (including the AP), considering the setting states of these two NAVs, can determine that it can respond to the Trigger frame and can then transmit a UL MU packet.

[0062] (1) When both the basic NAV and the intra-BSS NAV are not 0 (i.e., set), it is impossible to obtain the right to transmit, and it is impossible to respond to the Trigger frame (i.e., UL MU transmission is not possible).

[0063] (2) When the basic NAV is not 0 (i.e., set) and the intra-BSS NAV is 0 (i.e., not set), it is impossible to obtain the right to transmit, and it is impossible to respond to the Trigger frame (i.e., UL MU transmission is not possible).

[0064] (3) If the basic NAV is 0 (i.e., not set) and the intra - BSS NAV is not 0 (i.e., set), obtaining the transmission right is not possible, but responding to the trigger frame is possible (i.e., UL MU transmission is possible).

[0065] (4) If both the basic NAV and the intra - BSS NAV are 0 (i.e., not set), obtaining the transmission right is possible, and responding to the trigger frame is possible (i.e., UL MU transmission is possible).

[0066] The intra - BSS NAV is set when the BSSID of its own BSS is set as the value of the RA, TA, or BSSID field in the MAC frame stored in the physical packet received by the STA (including the AP). Or, when there is no TA in the control frame stored in the physical packet received by the STA (including the AP), there is an RA, and the value described in the RA is determined to be the same as the MAC address held as the TXOP holder that obtained the transmission right before, and the intra - BSS NAV was set when holding that TXOP holder (that is, when a frame is transmitted from the TXOP holder of the TXOP recognized as intra - BSS communication and there is no TA but there is an RA in the response frame to it, and it can be determined that the RA is addressed to the TXOP holder), the intra - BSS NAV is set. Also, when the STA (including the AP) cannot decode the physical packet but can determine from the header information of the physical packet that the communication is within the same BSS, the intra - BSS NAV is set. The header information of the physical packet in this case is, for example, the aforementioned BSS Color field. Or, the STA (including the AP) may determine that the communication in which the data frame is received based on the Parital AID field of the VHT - SIG - A field in the header of the physical packet (VHT PPDU) defined by the 802.11ac standard is within the same BSS.

[0067] In the 802.11ax standard, the AP does not necessarily have to have these two NAVs. That is, it is optional for the AP to have an intra-BSS NAV. When the AP does not have an intra-BSS NAV, its operation is the same as that of a normal operation with only one NAV up to the 802.11ac standard. The reason why the inra-BSS NAV is optional for the AP is that in the 802.11ax standard, it is always the AP that transmits the trigger frame, and it is always the STA that receives it and performs UL MU transmission as its response. That is, there is no case where the AP responds to the trigger frame in Figure 4.

[0068] <Trigger frame> Figure 5 is a diagram showing an example of the format of a trigger frame.

[0069] The Duration field (2 octets) is the Duration / ID field described above.

[0070] The Common Info field (8 octets or more) is an area indicating instruction information common to all STAs targeted in UL MU transmission. In addition to the CS Required subfield described above, the Common Info field includes a Trigger Type subfield indicating the type of trigger frame and a UL Length subfield indicating the time length of the UL MU packet.

[0071] The User Info List field (variable length in octets) consists of multiple User Info fields. Each User Info field notifies control information for an individual STA. The AID of an individual STA is specified in the AID12 subfield within the User Info field. Also, when targeting STAs (associated STAs) that are already connected to the AP using UL orthogonal frequency division multiple access (UL OFDMA) based random access (UORA) without specifying a particular STA, "0" is set in the AID12 subfield. When targeting STAs (unassociated STAs) that are not connected to the AP using UORA without specifying a particular STA, "2045" is set in the AID12 subfield. In addition to the AID12 subfield, User Info fields include an RU Allocation subfield indicating which RU is assigned for transmission and a UL HE-MCS subfield indicating the modulation and coding scheme (MCS) to be used for transmission, etc.

[0072] <Description of multi-AP> Multi-AP coordination (MAP) is a general term for the coordinated operation of multiple APs that make up an ESS.

[0073] For example, there is a cooperative operation where, after an AP acquires the right to transmit, it allocates a part of the wireless resources of the TXOP it has acquired to one or more other APs. Here, the AP that acquires the right to transmit and allocates a part of the wireless resources of the TXOP is the sharing AP, and the AP that receives the allocation of a part of the wireless resources is the shared AP. Also, wireless resources refer to time or frequency.

[0074] FIG. 6 shows an example of a MAP in a form where the source AP divides a part of the resources (time) of the TXOP it has obtained by itself and distributes it to the destination APs, without separating the resources (time) of a part of the TXOP in terms of frequency. In this case, the source AP distributes the TXOP to a plurality of destination APs in a time-division manner. The AP1, which is the source AP, obtains TXOP1 and uses a part of the time TXOP11 for itself. After the end of TXOP11, AP1 distributes the remaining part of the time TXOP12 to AP2, which is one of the destination APs. After the end of TXOP12, AP1 distributes the remaining part of the time TXOP13 to AP2, which is another one of the destination APs. The frequency bandwidth of the TXOP distributed to the destination AP is the same as the frequency bandwidth obtained by the source AP for the transmission right. For example, when the source AP has obtained four 20 MHz channels of a continuous 80 MHz channel, a plurality of destination APs will each use the 80 MHz channel in a time-division manner.

[0075] The method of using a plurality of reference frequency channels (20 MHz in the above example) together is called channel bonding. FIG. 7 is a diagram for explaining an example of channel bonding.

[0076] (a) of FIG. 7 shows an example of channel bonding for generating 40 MHz, 80 MHz, and 160 MHz bonding channels. In a BSS, STAs corresponding to various channel widths can be connected up to the maximum channel width specified as acceptable by the AP. The primary channel is a 20 MHz channel that all STAs (including the AP) constituting the BSS can operate on commonly. A beacon frame is always transmitted on the primary channel. A 20 MHz channel that is continuous with the primary channel and forms a 40 MHz bonding channel together with the primary channel becomes a secondary channel. In (a) of FIG. 7, an example is shown where the right side (higher frequency side) of the primary channel is the secondary channel. However, the arrangement of the secondary channel is not limited to the example in (a) of FIG. 7. Two 20 MHz channels that are continuous with the 40 MHz bonding channel composed of the primary channel and the secondary channel and form an 80 MHz bonding channel together with the 40 MHz bonding channel constitute a secondary 40 MHz channel (bonding channel). In (a) of FIG. 7, an example is shown where the left side (lower frequency side) of the primary channel is the secondary 40 MHz channel. However, the arrangement of the secondary 40 MHz channel is not limited to the example in (a) of FIG. 7. Four 20 MHz channels that are continuous with the 80 MHz bonding channel composed of the primary channel, the secondary channel, and the secondary 40 MHz channel and form a 160 MHz bonding channel together with the 80 MHz bonding channel constitute a secondary 80 MHz channel (bonding channel). In (a) of FIG. 7, an example is shown where the right side (higher frequency side) of the secondary channel is the secondary 80 MHz channel. However, the arrangement of the secondary 80 MHz channel is not limited to the example in (a) of FIG. 7. In 320 MHz channel bonding, a secondary 160 MHz channel (bonding channel) consisting of eight consecutive 20 MHz channels is configured to be connected to the previous 160 MHz bonding channel.

[0077] As shown in Fig. 7(b), the secondary channel and the secondary 80 MHz channel can be separated to secure a total of 160 MHz channel. In this case, it is called an 80 + 80 MHz bonding channel.

[0078] Fig. 8 is a diagram for explaining a method for obtaining a transmission right in an example of channel bonding shown in Fig. 7(a). The method described in Fig. 8 is applied when each AP or each STA obtains a transmission right with a channel width greater than 20 MHz. Fig. 8(a) explains a method for obtaining a transmission right in the case of 40 MHz channel bonding. Hereinafter, the case where the transmitting AP obtains the transmission right will be described as an example. The transmitting AP performs CS on the primary 20 MHz channel. When it is possible to obtain the transmission right for the primary 20 MHz channel, the CS status of the secondary 20 MHz channel is confirmed during the period of going back PIFS (SIFS + 1 slot time) from that point. When it is possible to obtain the transmission right without detecting a busy state during the PIFS period for the secondary 20 MHz channel, the transmitting AP transmits on the 40 MHz bonding channel. When a busy state is detected during the PIFS period for the secondary 20 MHz channel, it is determined that it is impossible to obtain the transmission right on the secondary 20 MHz channel, and the transmitting AP may transmit only on the primary 20 MHz channel, or may resume the operation from the confirmation of the CS status on the primary 20 MHz channel in order to try transmission on the 40 MHz channel again.

[0079] (b) of FIG. 8 illustrates a method for obtaining transmission rights in the case of 80 MHz channel bonding. When the source AP supports a channel width of up to 80 MHz in its own BSS, for example, based on the primary channel, one consecutive 20 MHz channel is set as the secondary channel, and two consecutive 20 MHz channels that form a 40 MHz bonding channel with the primary channel and the secondary channel are set as the secondary 40 MHz channels. The source AP notifies the STA in the beacon frame and the probe response frame of how to set the secondary channel and the secondary 40 MHz channel. Even when the source AP only uses up to 40 MHz channels in the BSS, it notifies the secondary channel in the same way. Also, in the case of 160 MHz channels or 80 + 80 MHz channels, the source AP notifies the secondary 80 MHz channels in the same way, and in the case of 320 MHz channels, it notifies the secondary 160 MHz channels in the same way. When the transmitting AP attempts to obtain transmission rights on an 80 MHz channel, similar to the case of the 40 MHz channel described above, starting from the time when it is determined that transmission rights can be obtained for the primary 20 MHz channel, the CS status is checked for each secondary 20 MHz channel and secondary 40 MHz channel within PIFS retroactively, and transmission is performed with the maximum channel width that clears the condition. That is, if the transmitting AP detects that the secondary 20 MHz channel is busy within PIFS, even if the secondary 40 MHz channel is not detected as busy within PIFS, it transmits only on the primary 20 MHz channel. Alternatively, expecting to secure a wider bandwidth at the next opportunity, the transmitting AP may resume operation from checking the CS status on the primary 20 MHz channel to attempt transmission on an 80 MHz channel again. When the primary 20 MHz channel and the secondary 20 MHz channel clear the CS condition and the secondary 40 MHz channel is detected as busy within PIFS, transmission can be performed on a 40 MHz channel using the primary 20 MHz channel and the secondary 20 MHz channel.That is, in order to transmit on an 80 MHz channel, it is a condition that the CS condition on the primary channel is cleared and that neither the secondary 20 MHz channel nor the secondary 40 MHz channel detects busy within the PIFS. Similarly, when transmitting on a 160 MHz channel, it is a condition that neither the secondary 20 MHz channel, the secondary 40 MHz channel, nor the secondary 80 MHz channel detects busy within the PIFS, based on the primary 20 MHz channel. When transmitting on a 320 MHz channel, it is a condition that neither the secondary 20 MHz channel, the secondary 40 MHz channel, the secondary 80 MHz channel, nor the secondary 160 MHz channel detects busy within the PIFS, based on the primary 20 MHz channel. The above is the basis of CS using channel bonding. However, it is also possible to use a method (puncture technique) in which the wideband channel is CSed in units of 20 MHz sub-channels and transmission is not performed on some of the 20 MHz channels that become busy. As methods for transmitting physical packets applying the puncture technique, there are a method of puncturing from the physical header and transmitting as one physical packet (puncture packet), and a method of transmitting the same physical packet in units of the remaining 20 MHz sub-channels without transmitting on some of the 20 MHz sub-channels (duplicate packet). This makes it easier to obtain the right to transmit over a wideband. Even when using the puncture technique, the right to transmit must be obtained on the primary 20 MHz channel. When transmitting a physical packet using the puncture technique, the physical header notifies which 20 MHz channel is being punctured. The combination of the 20 MHz sub-channels being punctured may be restricted. Thus, if the physical header is acquired on any 20 MHz sub-channel, it is possible to grasp on which other 20 MHz sub-channels transmission is being performed. The AP and STA notify each other whether they can receive and decode a physical packet using the puncture technique (the AP notifies in the beacon frame or probe response frame, and the STA notifies in the association request frame or reassociation request frame), and transmit the physical packet only to compatible counterparts.In the MAP, it is assumed that the source AP can transmit a punctured physical packet when the destination AP can receive the punctured physical packet.

[0080] FIG. 9 shows an example of the MAP in a form where the source sharing AP divides a part of the resources (time) of the TXOP acquired by itself in terms of frequency and distributes them to a plurality of destination sharing APs. In this case, the source sharing AP divides the TXOP by frequency among the plurality of destination sharing APs. The AP1, which is the source sharing AP, acquires TXOP1 and uses a part of the time TXOP11 by itself. After the end of TXOP11, the AP1 distributes the TXOP12 of the first frequency width obtained by dividing the frequency width of the remaining part of the time TXOP12 to the AP2, which is one of the destination sharing APs, and distributes the TXOP12 of the second frequency width to the AP3, which is the other one of the destination sharing APs. The total of the frequency widths assigned to each destination sharing AP is the same as or narrower than the frequency width in which the source sharing AP has acquired the transmission right, that is, it is equal to or less than the frequency width in which the source sharing AP has acquired the transmission right. Naturally, the frequencies assigned to each destination sharing AP are within the frequency in which the source sharing AP has acquired the transmission right. This is because the TXOP, which is the period in which the transmission right is acquired, also extends in the frequency direction, and the TXOP1 of the source sharing AP protects a certain frequency width, so any frequency within that protection can be distributed to other APs. For example, in FIG. 9, when the source sharing AP1 acquires an 80 MHz channel, 40 MHz is assigned to the destination sharing AP2 and 40 MHz is assigned to the destination sharing AP3. In this case, the total of the frequencies assigned to the AP2 and the AP3 is 80 MHz, which is the same as the 80 MHz width acquired by the AP1. Alternatively, 40 MHz may be assigned to the AP2 and 20 MHz may be assigned to the AP3. In this case, the total of the frequencies assigned to the AP2 and the AP3 is 60 MHz, which is narrower than the 80 MHz width acquired by the AP1.

[0081] Of course, a time-division MAP and a frequency-division MAP may be combined. Of course, while the shared source AP allocates a part of the wireless resources of the TXOP to other APs, the own AP may also use a part of the wireless resources of the TXOP again in the same manner as other APs. For example, in FIG. 6, after TXOP12 and TXOP13, if there is remaining time until TXOP1 ends, AP1 may use the TXOP again. Also, for example, in FIG. 9, although TXOP12 is allocated to AP2 and AP3 by frequency division, AP1 itself may use a part of the frequency of TXOP12 and utilize TXOP12 in parallel with AP2 and AP3.

[0082] When sharing some of the wireless resources of a TXOP with a destination AP, the AP uses a trigger frame. In the conventional 802.11ax standard, the trigger frame is used by the AP to allocate some of the wireless resources of the TXOP to the STAs connected to that AP. Therefore, in this embodiment, when the source AP allocates some of the wireless resources of the TXOP to the destination AP, a different Trigger Type subfield is defined. Alternatively, a new control frame different from the trigger frame may be defined. Alternatively, it may be made available for this embodiment in which the AP allocates some of the wireless resources of the TXOP to another AP by using the existing Trigger Type subfield, specifically the currently unused (reserved) field of the Basic variant (referred to as the Basic Trigger frame) generally used to indicate UL MU transmission, or by redefining some fields while maintaining backward compatibility. When the Basic Trigger frame is modified and reused, or when a new Trigger Type subfield is defined, it is conceivable that the User Info field is the same as in the existing case. In that case, for example, an identifier is assigned to each AP to identify each AP within the ESS, and the identifier of that AP is placed in the AID12 subfield. In this case, since the AID used by a normal STA is 1 to 2007 and a value with a special meaning has been defined as the AID12 subfield in the existing trigger frame as described above, the identifier of the AP may be assigned while avoiding those values. For example, when forming an ESS, the first AP that starts forming the ESS may assign identifiers to other APs, or the identifiers of each AP may be manually specified via a user interface. When defining a new control frame, a field such as the AID12 subfield as described above may be provided in the User Info field, and the source AP may notify the destination AP to which it allocates some of the wireless resources of the TXOP by the identifier of the AP, or may notify the MAC address of the destination AP as it is.While the former can shorten the field specifying the AP, a method for assigning an identifier for identifying APs is required.

[0083] In the shared destination AP to which a part of the wireless resources of the TXOP is allocated from the shared source AP, it is used as if the AP itself has acquired the transmission right among the wireless resources allocated to each. For example, in FIG. 6, during TXOP12, AP2 transmits data frames to STA21 and STA22 connected to AP2 and receives response frames such as Ack frames and BlockAck frames for them, or transmits trigger frames to STA21 and STA21 to cause each to transmit data frames and transmit response frames for them. Of course, if it fits within TXOP12, these consecutive frame exchanges may be performed.

[0084] <Notification of MAP compatibility capability> When implementing MAP, in the shared source AP, it is necessary to grasp in advance that the candidate shared destination AP is an AP that can perform a special operation related to NAV as described below. Also, in the AP that becomes the shared destination, when reallocating wireless resources to the STAs of its own BSS under the MAP operation, it is necessary to grasp in advance that the target candidate STA is an STA that can perform a special operation related to NAV as described below. That is, it is necessary to notify whether the capabilities (capabilities) indispensable for MAP correspondence, such as special operations related to NAV as described below, can be supported.

[0085] For example, if the notification related to the capability of whether the MAP operation is possible is included in the beacon frame transmitted by each AP and the action frame for transmission to other APs and transmitted, the plurality of APs constituting the ESS can grasp the compatibility of the MAP operation with each other by receiving those frames.

[0086] An action frame is also a type of management frame. The Subtype field of the action frame is indicated as an action frame. The Category subfield in the Action field placed at the beginning of the Frame Body field of the action frame indicates the general category of the action frame. Further, the Action Details subfield following the Category subfield stores subfields representing more specific types of action frames according to the Category subfield.

[0087] Using, for example, one of the information elements placed in the Frame Body field of the beacon frame or action frame, it is possible to notify that the MAP operation is possible. The information element notifying that the MAP operation is possible may also include notifications related to capabilities other than the MAP operation. For example, there is an EHT Capabilities element as a field for notifying capabilities related to the 802.11be standard, and it may be placed here. Alternatively, an information element for notifying new information related to the MAP operation (and other information) may be defined. In this case, a new identifier (Element ID, Element ID Extension) will be defined as this information element.

[0088] Figure 10 shows an example of the format of the information element included in the Frame Body of the MAC frame. The information element includes an Element ID field (1 octet), a Length field (1 octet), an Element ID Extension field (0 or 1 octet), and an Information field (variable length in octets).

[0089] The Element ID Extension field is used when the number of the Element ID for identifying an information element reaches the upper limit that can be represented by 1 octet. Only when the Element ID takes the maximum value of "255", the Element ID Extension field is added, and the Subelement ID for identifying the information element can be added.

[0090] The Element ID Extension field is also 1 octet. In the wireless LAN standard compliant with the current 802.11 standard, the value "0" of this field is Reserved, and the values of "1" or more are assigned to identify information elements in the same way as the Element ID. Here, the unique value for identifying the information element is described.

[0091] The Length field indicates the length (size) of the information element excluding the Element ID field and the Length field. The Information field indicates the content of the information.

[0092] When a STA connected to an MAP-capable AP has a part of the radio resources of the TXOP assigned from the shared source AP to its own AP (the AP to which the STA is connected) further reallocated from its own AP, the STA performs a special operation related to the NAV under certain conditions and transmits to its own AP that it is possible to transmit data frames, etc., that is, it is possible to transmit under the instruction of its own AP within the TXOP divided from other APs. Also, when the STA notifies its own AP in this way, it may include an information element notifying that the MAP operation is possible in the association request frame or re-association request frame. Also, such a STA can grasp in advance whether the candidate AP for connection has the same information element in the beacon frame or probe response, and thus whether the AP is capable of MAP operation. Therefore, when the STA confirms that the AP to which the association request frame or re-association request frame is to be transmitted is capable of MAP operation, it may include the previous information element in the association request frame or re-association request frame and notify its own AP that it is capable of handling it. When the AP receives from the STA a notification in the association request frame or re-association request frame that it is possible to transmit under the instruction of its own AP within the TXOP divided from other APs, it may include an information element notifying that the MAP operation is possible in the association request frame or re-association response frame again.

[0093] <map candidate set> As described above, when the number of APs capable of MAP operation is limited even within the same ESS, for example, if the number of APs actually performing coordinated MAP operation is limited, each AP performing MAP operation needs to identify other APs that are candidates for coordinated MAP operation. Such a group of APs that are candidates for coordinated MAP operation is referred to as a MAP candidate set. In the description part regarding the NAV operation described later, the part that describes APs within the same ESS etc. should be read as APs in the MAP candidate set when the number of APs capable of MAP operation is limited even within the same ESS.

[0094] <Example of operation for an AP to be able to use a part of the wireless resources of the TXOP allocated from another AP> As described above, in the 802.11ax standard, it is optional for an AP to have an intra - BSS NAV, and it may have only the conventional single NAV.

[0095] Hereinafter, an example of the MAP operation for enabling an AP to use a part of the wireless resources of the TXOP allocated from another AP will be described. The MAP operation examples are classified into examples implemented in an AP and examples implemented in a STA. First, the MAP operation examples implemented in an AP will be described.

[0096] <AP operation example 1: Only one NAV> First, an operation example will be described in which, when only one NAV is set by the reception processing unit 90, the transmission processing unit 80 can use a part of the wireless resources of the TXOP allocated from another AP regardless of the NAV.

[0097] In this case, when the AP reception processing unit 90 receives a frame in which a part of the TXOP radio resources is shared from another AP addressed to its own AP, the transmission processing unit 80 transmits while ignoring the NAV within the allocated radio resources. FIG. 11 is a diagram for explaining an example of the AP operation example 1. In FIG. 11, AP1 is the sharing source AP, and a part of the radio resources of the TXOP acquired by AP1 is allocated to the sharing destination AP2. The frame for allocating a part of the radio resources of the TXOP to this AP2 is the MAP Transmission Sharing Trigger frame (MAP TXS TF) in the figure. Here, the frame for allocating a part of the radio resources of the TXOP to another AP is regarded as a kind of trigger frame. When allocating only to AP2, the RA of the MAP TXS TF is set to the MAC address of AP2.

[0098] For example, when the RA of the MAP TXS TF designates the MAC address of its own AP, when AP2 receives and decodes the MAP TXS TF, it can be seen from the Type field and the Subtype field that the MAP TXS TF is a trigger frame that is a control frame as a frame type, and it can be seen from the Trigger Type subfield that the MAP TXS TF is used when an AP that is a MAP allocates a part of the radio resources of the TXOP to another AP. Therefore, AP2 satisfies the condition that it has received a frame in which a part of the radio resources of the TXOP is shared from another AP addressed to its own AP. Therefore, if AP1, for example, transmits a frame addressed to an STA within the BSS1 constituted by AP1, or transmits a CTS frame addressed to AP1, when AP2 receives it, even in a state where the NAV is set, AP2 (transmission processing unit 80) can ignore the NAV and use the TXOP according to the MAP TXS TF, and can perform transmissions such as reallocating the radio resources allocated to the STAs within the BSS constituted by AP2 itself. A CTS frame addressed to its own STA (including an AP) is particularly called a CTS-to-self frame. Addressing to its own STA means that the RA is set to the MAC address of its own STA.

[0099] Figure 11 shows an example in which, after the AP2 that has received the MAP TXS TF transmits a response frame (in Figure 11, the Transmission Sharing Response frame (TXS RSP) corresponds to this) to notify the AP1 that it will use some of the allocated radio resources, the AP2 transmits a trigger frame (in Figure 11, the Trigger frame (TF) corresponds to this) for instructing the STA21 and STA22 connected to the AP2 to perform UL MU transmission. For example, the AP2 is configured to transmit the TXS RSP after the SIFS of the MAP TXS TF and transmit the TF after the SIFS of the TXS RSP. For example, when it is difficult for the AP2 to prepare for transmitting the TXS RSP within the SIFS, the AP2 negotiates in advance with the AP1 the adjustment time required by the AP2. When the AP1 transmits the MAP TXS TF in a physical frame, padding processing is performed after the MAP TXS TF in accordance with the adjustment time, so that the AP2 can obtain the processing time for transmission preparation while making the time between actual physical packets the SIFS.

[0100] In order for the AP2 to transmit the TXS RSP to the AP1, in addition to the RA in the MAC header of the MAP TXS TF, there must be an SA, and the MAC address of the AP1 must be set in the SA. The AP2 copies the MAC address of the AP1 set in the SA of the MAP TXS TF and sets it in the RA of the TXS RSP. It is desirable to include the SA in the TXS RSP to identify which AP is responding on the AP1 side, and the AP2 sets its own MAC address in the SA when transmitting the TXS RSP to the AP1.

[0101] Here, in the RA of the received frame, the MAC address of its own AP is set for AP2. When it determines that the frame is a MAP TXS TF, it ignores the NAV and transmits the frame. Additionally, as a transmission condition, it may be further limited to the case where the AP of the same ESS is the source AP. To determine this, the TA of the MAP TXS TF may be used as described above. Since AP1 knows in advance that AP2 is one of the APs constituting the same ESS, when AP2 receives a MAP TXS TF with its own MAC address described in the TA, it can determine that the frame was transmitted by AP1 of the same ESS. Since the wireless resources of a part of the TXOP are only used when allocated to the APs of the same ESS, it is appropriate to further condition whether to transmit the TXS RSP frame on the condition that the MAP TXS RF is transmitted from one of the APs constituting the same ESS. This is because if the NAV is not set before AP2 receives the MAP TXS TF, and if the MAP TXS TF is addressed to its own AP, the NAV is not set, so AP2 can transmit the TXS TF frame. However, even in this case, AP2 cannot transmit the TF frame to STA21 and STA22. This is because when receiving a frame addressed to its own STA (including the AP), the NAV is not set, but instead, it has a timer, which is a similar concept, and it knows that it is within the TXOP of AP1 that started the TXOP (is the TXOP holder), and it should not attempt to acquire the transmission right during that TXOP.

[0102] When AP1 allocates a part of the TXOP resources to a plurality of APs, for example, AP2 and AP3, the broadcast address is set in the RA of the MAP TXS TF. Therefore, for AP2 to recognize that the MAP TXS TF allocates a part of the wireless resources of the TXOP to its own AP, for example, it is done by the fact that there is an identifier allocated to its own AP in the AID12 subfield in one of the User Info fields in the MAP TXS TF, similar to the conventional trigger frame.

[0103] In order for the AP to easily grasp that the received frame is a frame from an AP within the same ESS, the SSID, which is the identifier of the ESS as described above, may be put into the MAP TXS TF. Note that the SSID is put into some management frames, and in that case, it is expressed in the form of an information element. This is because the SSID has a variable length of up to 32 octets in octet units. The trigger frame is a control frame and usually does not contain an information element. This is to reduce the processing load when receiving a control frame. When storing a field whose length may change in a control frame, instead of putting length information like an information element and cutting out the corresponding field, the field can be grasped by putting in detailed types or special values indicating the end of the field. Therefore, when putting the SSID into the MAP TXS TF as well, for example, it is put at the end of the frame body part (before the FCS field). Naturally, if a configuration allowing the insertion of length information and the SSID value is acceptable, that is also fine. Alternatively, a 6-octet value may be defined as the identifier of the ESS separately from the SSID (let's call this, for example, the ESSID) and used in the same way as the MAC address. When using the ESSID, it is necessary to make it well-known in advance within the same ESS.

[0104] Alternatively, in order for an AP to easily grasp that it is from the same ESS, a new identifier, ESS color, different from the SSID for identifying the same ESS, such as the BSS Color field, may be provided. In this case, the concept of putting the identifier for identifying the same ESS, for example, in the BSS Color field is basically followed. Usually, it is used to identify whether it is its own BSS, but for a certain value, it is used to notify that it is the same ESS. The ESS color value is determined by some method among the APs within the same ESS and shared among the APs within the same ESS. For example, one AP that starts the configuration of the ESS, etc., may determine the ESS color value, or the user may determine it and input it to each AP via a controller or the like. Also, like the conventional BSS color, the value may be changeable in the middle.

[0105] Note that in AP operation example 1, when AP2 is allocated a part of the wireless resources of the TXOP, one of the STAs already connected to AP2 has acquired the transmission right, and in the case where there is intra-BSS communication and AP1 does not detect it. In this case, since AP2 may transmit ignoring the NAV, there is a risk of collision between the communication of AP2 and the intra-BSS communication. Also, when there is communication within another BSS (not limited to the same ESS) detected by AP2 but not detected by AP1, again AP2 may transmit ignoring the NAV, so there is a risk of collision with the communication in another BSS. Next, AP operation example 2 for eliminating this risk of collision will be described.

[0106] <AP Operation Example 2: Two NAVs (basic NAV, intra-BSS NAV) in the 802.11ax standard> In AP operation example 2, AP2 has two NAVs, a basic NAV and an intra-BSS NAV. The difference between AP operation example 2 and AP operation example 1 is that when the intra-BSS NAV is set, even if the AP receives a frame from another AP that shares a part of the TXOP wireless resources addressed to itself, it cannot ignore the intra-BSS NAV and transmit within the allocated wireless resources. On the other hand, when only the basic NAV is set, similar to AP operation example 1, the AP can ignore the basic NAV and transmit frames according to the allocated frames from other APs.

[0107] Figure 12(a) is a diagram for explaining an example of AP operation example 2 when only the basic NAV is set. Even if the basic NAV is set, if the intra-BSS NAV is not set, AP2 ignores the basic NAV, receives the MAP TXS TF, which is an allocated frame for MAP operation, from AP1, transmits a TXS RSP in response, and then transmits a TF to STA21 and STA22 connected to AP2. Figure 12(b) is a diagram for explaining an example of AP operation example 2 when the intra-NAV is set. AP2 respects the intra-NAV, does not transmit a TXS RSP for the MAP TXS TF, and also does not transmit a TF to STA21 and STA22. If the intra-NAV ends during the MAP TXS TF and the intra-NAV is not set at the stage of determining whether to transmit a TXS RSP after a fixed time of the MAP TXS TF (for example, after SIFS, similar to the transmission of a normal TF), even if the basic NAV is set, it will be the same as Figure 12(a), so AP2 can transmit.

[0108] Figure 13 shows the relationship between the setting states of the two NAVs in AP operation example 2 and whether a part of the wireless resources of the TXOP can be used when allocated from another AP (the item in the figure is expressed as "MAP transmission").

[0109] (1) If both the basic NAV and the intra-BSS NAV are not 0 (i.e., are set), acquisition of the right to transmit is not possible, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 12.

[0110] (2) If the basic NAV is not 0 (i.e., is set) and the intra-BSS NAV is 0 (i.e., is not set), acquisition of the right to transmit is not possible, and MAP transmission is possible (i.e., the allocated radio resources can be used). This case corresponds to (a) in FIG. 12.

[0111] (3) If the basic NAV is 0 (i.e., is not set) and the intra-BSS NAV is not 0 (i.e., is set), acquisition of the right to transmit is not possible, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 12.

[0112] (4) If both the basic NAV and the intra-BSS NAV are 0 (i.e., are not set), acquisition of the right to transmit is possible, and MAP transmission is possible (i.e., the allocated radio resources can be used).

[0113] By doing this, transmission becomes possible when radio resources are allocated from other access points to be coordinated.

[0114] In AP operation example 2, similar to AP operation example 1, the AP may limit the transmission conditions such that MAP transmission is possible only when the AP of the same ESS is the transmission source. Also, the method of determining whether the AP is allocated when the RA of the MAP TXS TF is a broadcast address is the same as in AP operation example 1. The method in AP operation example 1 for the receiving AP to easily determine that it is from an AP of the same ESS can also be applied to AP operation example 2.

[0115] In AP operation example 2, in a situation where intra-BSS communication is taking place and AP1 fails to detect it, the situation in AP operation example 1 where AP2 transmits and collides with the intra-BSS communication can be avoided. On the other hand, in AP operation example 2, although there is communication within another BSS that is detected by AP2 but not by AP1, when AP1 transmits a MAP TXS TF, AP2 may ignore the basic NAV and transmit, potentially resulting in a collision with communication in another BSS. Next, AP operation example 3 that resolves this risk of collision will be described.

[0116] <AP operation example 3: Two NAVs (a new ESS NAV for MAP (which replaces the intra-BSS NAV of non-AP STAs within the BSS), basic NAV)> AP operation example 3 provides two NAVs: a NAV for MAP (referred to as ESS NAV) that is set when a frame within the same ESS (including its own BSS) is received, and a NAV (referred to as basic-NAV) that is set under other conditions (when a frame or packet that is not within the same ESS is received). In the 802.11ax standard, STAs set the intra-BSS NAV and the basic NAV. In AP operation example 3, the intra-BSS NAV is not set, and the ESS NAV is set without distinction whether a frame within its own BSS or a frame from another AP / STA within the same ESS is received. The ESS NAV is an extension of the intra-BSS NAV in the case where there are two NAVs set in the 802.11ax standard. The ESS NAV encompasses the intra-BSS NAV.

[0117] If the AP includes the BSSID of its own BSS (i.e., the MAC address of the AP of its own BSS) as the RA, TA, or BSSID field value of the received MAC frame (in the case of a frame of its own BSS) or includes the MAC address of an AP within the same ESS, it determines that it has received a frame within the same ESS and sets the ESS NAV. Also, if the AP can determine that the received frame is a response frame to the TXOP holder of the TXOP recognized as communication within the same BSS, it sets the ESS NAV.

[0118] The determination method in this case is the same as the determination method for intra-BSS NAV in the 802.11ax standard NAV. Also, the ESS color (discussed in AP operation example 1) can be put in the header of the physical packet, or the BSS color of each BSS within the ESS can be made mutually known among BSSs in advance using the existing BSS Color field, so that the AP can grasp the BSS color and determine that the frame or physical packet received by the AP is a frame or physical packet due to communication within the same ESS. As a method of putting the ESS color in the header of the physical packet, for example, a specific value can be provided to identify that it is the same ESS and put in the BSS Color field value, or a new ESS Color field can be provided. The same determination can be made when using the Partial AID field.

[0119] If the AP does not meet the ESS NAV setting conditions (including the case where it cannot determine whether it is the same ESS), it sets the basic NAV. Therefore, the basic NAV setting conditions here are slightly different from those of the basic NAV in the conventional two NAVs. In AP operation example 2, the AP respected the intra-BSS NAV, while in AP operation example 3, the AP respects the basic NAV, which is the concept paired with the ESS NAV. This is a behavior similar to when, in the case of having the conventional two NAVs, the STA respects the basic NAV when responding to the trigger frame from the AP. In AP operation example 3, when the basic NAV is set, even if the AP receives a frame that shares a part of the TXOP radio resources from another AP addressed to itself, it cannot ignore the basic NAV and transmit within the allocated radio resources. On the other hand, when only the ESS NAV is set, the AP can ignore the ESS NAV and transmit according to the allocation frame from another AP.

[0120] Figure 14(a) is a diagram for explaining AP operation example 3 when only the ESS NAV is set. AP2 ignores the ESS NAV, transmits a TXS RSP in response to the MAP TXS TF from AP1, and then transmits the TF to STA21 and STA22 connected to AP2. Figure 14(b) is a diagram for explaining AP operation example 3 when the basic NAV is set. AP2 respects the basic NAV, does not transmit a TXS RSP in response to the MAP TXS TF, and also does not transmit the TF to STA21 and STA22. If the basic NAV ends during the MAP TXS TF and the basic NAV is not set at the stage of determining whether to transmit the TXS RSP after a fixed time of the MAP TXS TF, even if the ESS NAV is set, it will be the same as in Figure 14(a), so AP2 can transmit.

[0121] FIG. 15 shows the relationship regarding whether a part of the radio resources of the TXOP can be used (expressed as "MAP transmission" in the figure) when the setting states of two NAVs and a part of the radio resources are allocated from other APs.

[0122] (1) When both the basic NAV and the ESS NAV are not 0 (i.e., set), it is impossible to acquire the right to transmit, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 14.

[0123] (2) When the basic NAV is not 0 (i.e., set) and the ESS NAV is 0 (i.e., not set), it is impossible to acquire the right to transmit, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 14.

[0124] (3) When the basic NAV is 0 (i.e., not set) and the ESS NAV is not 0 (i.e., set), it is impossible to acquire the right to transmit, and MAP transmission is possible (i.e., the allocated radio resources can be used). This case corresponds to (a) in FIG. 14.

[0125] (4) When both the basic NAV and the ESS NAV are 0 (i.e., not set), it is possible to acquire the right to transmit, and MAP transmission is possible (i.e., the allocated radio resources can be used).

[0126] In AP operation example 3, similar to AP operation example 1, the conditions for MAP transmission may be limited such that MAP transmission is possible only when the AP of the same ESS is the transmission source. Also, the method for determining whether the RA of the MAP TXS TF is the broadcast address and is allocated to the local AP is the same as in AP operation example 1. The method for the receiving AP to easily determine that the received frame or physical packet in AP operation example 1 is transmitted from the AP of the same ESS can also be applied to AP operation example 3.

[0127] In AP operation example 3, when AP1 does not detect the situation where communication is being performed within the BSS of AP2, if AP2 detects this, even if the ESS NAV is set, it will transmit, so this transmission may collide with intra-BSS communication. On the other hand, in a situation where there is communication within another BSS outside the ESS that is detected by AP2 but not by AP1, the situation where AP2 transmits and this transmission collides with communication within another BSS outside the ESS can be avoided. Next, AP operation example 4 that eliminates this risk of collision will be described.

[0128] <AP Operation Example 4: Three NAVs (intra-BSS NAV, ESS NAV, basic NAV)> The operation example AP4 is similar to the AP operation example 3, but the difference is that in the AP operation example 3, the condition for setting the ESS NAV included the case of receiving a frame of its own BSS, while in the AP operation example 4, the AP distinguishes and sets the ESS NAV and the intra-BSS NAV, and then respects the basic NAV and the intra-BSS NAV. Whether to set the intra-BSS NAV is the same as the condition for setting the intra-BSS NAV in the case of the conventional two NAVs. That is, when the AP demodulates the received packet to obtain a MAC frame and determines that the same BSSID as its own BSS is included in the MAC header, the AP extracts the NAV value from the MAC header and sets the NAV from that value. When the AP cannot demodulate the received packet, if it determines that it has received a packet of its own BSS based on the BSS color value in the header of the physical packet, the AP extracts the TXOP from the header of the physical packet and sets the NAV according to the TXOP. The AP sets the ESS NAV when it can determine that the communication is within the same ESS but not within its own BSS. The condition for setting the ESS NAV may be obtained by excluding the condition for setting the intra-BSS NAV from the condition for setting the ESS NAV in the case of the AP operation example 3. When neither the setting condition of the intra-BSS NAV nor the setting condition of the ESS NAV is met, the AP sets the basic NAV. In the AP operation example 4, when either the basic NAV or the intra-BSS NAV is set, the AP does not transmit even if it receives a frame from another AP that shares a part of the radio resource of the TXOP addressed to itself. On the other hand, when only the ESS NAV is set, the AP can ignore the ESS NAV and transmit according to the allocated frame from another AP.

[0129] FIG. 16(a) is a diagram for explaining an example operation 4 of an AP when only ESS NAV is set. When neither basic NAV nor intra-BSS NAV is set, even if ESS NAV is set, AP2 ignores the ESS NAV, transmits a TXS RSP in response to a MAP TXS TF from AP1, and then transmits a TF to STAs STA21 and STA22 connected to AP2. FIG. 16(b) is a diagram for explaining an example operation 4 of an AP when at least one of basic NAV or intra-BSS NAV is set. AP2 respects at least one of basic NAV or intra-BSS NAV, does not transmit a TXS RSP in response to a MAP TXS TF, and also does not transmit a TF to STA21 and STA22. If basic NAV was set but ended during a MAP TXS TF and basic NAV is not set at the stage of determining whether to transmit a TXS RSP after a fixed time of the MAP TXS TF and only ESS NAV is set, since it is the same as FIG. 16(a), the AP may transmit. Also, if intra-BSS NAV was set but ended during a MAP TXS TF and intra-BSS NAV is not set at the stage of determining whether to transmit a TXS RSP after a fixed time of the MAP TXS TF and only ESS NAV is set, since it is the same as FIG. 16(a), the AP may transmit.

[0130] FIG. 17 shows the relationship between the setting states of three NAVs and whether a part of the radio resources of a TXOP can be used when allocated from another AP (the item in the figure is expressed as "MAP transmission").

[0131] (1) When all of basic NAV, intra-BSS NAV, and ESS NAV are not 0 (i.e., are set), it is impossible to acquire the right to transmit, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to FIG. 16(b).

[0132] (2) When both the basic NAV and the intra-BSS NAV are not 0 (i.e., set), and the ESS NAV is 0 (i.e., not set), it is impossible to acquire the transmission right, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 16.

[0133] (3) When both the basic NAV and the ESS NAV are not 0 (i.e., set), and the intra-BSS NAV is 0 (i.e., not set), it is impossible to acquire the transmission right, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 16.

[0134] (4) When the basic NAV is not 0 (i.e., set), and both the intra-BSS NAV and the ESS NAV are 0 (i.e., not set), it is impossible to acquire the transmission right, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 16.

[0135] (5) When the basic NAV is 0 (i.e., not set), and both the intra-BSS NAV and the ESS NAV are not 0 (i.e., set), it is impossible to acquire the transmission right, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 16.

[0136] (6) When both the basic NAV and the ESS NAV are 0 (i.e., not set), and the intra-BSS NAV is not 0 (i.e., set), it is impossible to acquire the transmission right, and MAP transmission is not possible (i.e., the allocated radio resources cannot be used). This case corresponds to (b) in FIG. 16.

[0137] (7) If both the basic NAV and the intra-BSS NAV are 0 (i.e., not set), and the ESS NAV is not 0 (i.e., set), obtaining the right to transmit is not possible, but MAP transmission is possible (i.e., the allocated radio resources can be used). This case corresponds to (a) in FIG. 16.

[0138] (8) If the basic NAV, the intra-BSS NAV, and the ESS NAV are all 0 (i.e., not set), obtaining the right to transmit is possible, and MAP transmission is possible (i.e., the allocated radio resources can be used).

[0139] In AP operation example 4, similar to AP operation example 1, the conditions for MAP transmission may be limited such that MAP transmission is possible only when the AP of the same ESS is the transmission source. Also, the method for determining whether the RA of the MAP TXS TF is the broadcast address and is assigned to the local AP is the same as in AP operation example 1. The method in AP operation example 1 for the receiving AP to easily determine that it is from the AP of the same ESS can also be applied to this AP operation example 4.

[0140] In the AP operation example, when AP1 does not detect the situation where communication is being carried out within the BSS of AP2, even if AP2 detects it, since the intra-BSS NAV is set, AP2 will not transmit, so it is possible to avoid the situation where the communication of AP2 collides with the intra-BSS communication. Also, in the situation where there is communication within another BSS outside the ESS detected by AP2 but not detected by AP1, even if AP1 transmits the MAP TXS TF to AP2, since the basic NAV is set, AP2 will not transmit, so it is possible to avoid the situation where AP2 transmits and its transmission collides with the communication within another BSS outside the ESS.

[0141] Next, the MAP operation example implemented in the STA will be described.

[0142] <Example of the operation of the STA using the partial radio resources of the TXOP allocated from another AP to the AP (own AP) to which the STA is connected and further allocated from the own AP to the STA> Here, the operation of the STA under the shared AP will be described. Since the STA compliant with the 802.11ax standard supports UL MU transmission, the implementation example in the case of having three NAVs as in AP operation example 4 and the conventional case where it is usually expected to have two NAVs will be sequentially described, followed by the implementation example in the case of having only one NAV and realizing the expected operation similar to the case of having two NAVs.

[0143] <STA operation example 1: The STA treats the frames transmitted by the AP within the same ESS in the same way as the frames within the same BSS.> In STA operation example 1, the STA has two NAVs, namely the intra - BSS NAV and the basic NAV, and treats the frames transmitted by the AP within the same ESS in the same way as the frames transmitted by the AP or STA within the same BSS. That is, when the STA receives a frame transmitted by an AP other than the AP to which the STA is connected and within the same ESS, it sets the intra - BSS NAV in the same way as when the own AP transmits.

[0144] To achieve this, the STA needs to know in advance which APs are within the same ESS. For this purpose, for example, the AP to which the STA is connected includes information about the APs within the same ESS in the beacon frame, probe response frame, or association response frame. For the notification of this information, for example, an information element is used. This information may be added to the information element for performing the capability notification related to the previous MAP operation, or a new information element for notifying the information of the APs within the same ESS may be provided.

[0145] FIG. 18 is a diagram for explaining an example of the STA operation example 1. After AP2 receives the MAP TXS TF from AP1 and transmits the TXS RSP, which is a response thereto, to AP1, it transmits the TF to STA21 and STA22 connected to AP2. STA21 and STA22 each determine that the transmission of the TF from AP1 is a transmission within the same ESS and set the intra-BSS NAV. Therefore, STA21 and STA22 can respond to the TF from AP2 and transmit the data frames Data1 and Data2 to AP2 by UL MU, respectively. If the basic NAV is set in STA21 or STA22, STA21 or STA22 does not respond to the TF (strictly, when the CS Required subfield of the TF is "1").

[0146] STA21 and STA22 connected to AP2 determine whether they satisfy the normal setting conditions of the intra-BSS NAV by checking whether the BSSID containing the MAC address of the AP to which the own STA is connected is the same in the address field of the received frame as described above. However, in addition to this, the STA corresponding to the MAP operation also includes in the determination of the setting conditions whether the MAC address of the AP within the same ESS is included in the SA of the received frame, and sets the intra-BSS NAV when this condition is met. Also, as described above, when ESS information or the like is included in the header of the physical packet, the STA determines that the received frame is a frame within the same BSS based on this and sets the intra-BSS NAV. In FIG. 18, since the SA of the MAP TXS TF is AP1 and STA21 and STA22 recognize that AP1 is an AP in the same ESS as AP2, STA21 and STA22 set the intra-BSS NAV. Note that when the MAP TXS TF is unicast from AP1 to AP2, AP2 is set in the RA, so the normal setting conditions are satisfied and the intra-BSS NAV is set. However, even when the RA is set to the broadcast address in the MAP TXS TF, since the SA is AP1, STA21 and STA22 set the intra-BSS NAV according to the determination of the above-described setting conditions.

[0147] In STA operation example 1, even when AP1 does not share a part of the TXOP radio resources with AP2, STA21 and STA22 set the intra-BSS NAV. Therefore, if AP2 does not detect the transmissions detected by STA21 and STA22, STA21 and STA22 will transmit a response to the TF transmitted by AP2.

[0148] To solve this problem, for example, even when an AP within the same ESS transmits a MAP TXS TF, in all cases, STA21 and STA22 do not set the intra-BSS NAV, and STA21 and STA22 set the intra-BSS NAV only when an AP within the same ESS transmits a MAP TXS TF to the self-AP. In this case, it is determined whether the RA of the received frame is the self-AP, and when the RA of the received frame is the self-AP, STA21 and STA22 set the intra-BSS NAV. Alternatively, when the RA of the received frame is the broadcast address, if there is a field that further specifies an individual STA / AP, such as the AID12 field, it is determined whether the self-AP is specified by that field, and when the self-AP is specified, STA21 and STA22 set the intra-BSS NAV. However, in these cases, for example, when the sharing source AP first secures the TXOP by transmitting a CTS-to-self frame or the like, the intra-BSS NAV is not set, and then when a part of the TXOP radio resources is allocated to the AP to which the STA connects, and when the radio resources are redistributed from the AP to which the STA connects to the STA, the SAT cannot transmit. As an example of this solution method, there is the method described in STA operation example 4.

[0149] As another solution, for frames transmitted from other APs within the same ESS, if the received power level (e.g., notified as receive signal strength indicator (RSSI)) is below a certain value (less than at least -62 dBm, e.g., -72 dBm or -82 dBm), the STA sets the intra-BSS NAV, and if it is greater than that value, the STA sets the basic NAV. By doing so, when receiving a frame from an AP within the same ESS that is not a frame of its own BSS and the received power level is relatively low, even if communications in different BSSs collide, it is considered that there is no problem in setting the intra-BSS NAV because the signal-to-interference ratio (SIR) is large enough to continue communications. This incorporates the concept of spatial reuse (SR) in the 802.11ax standard.

[0150] In STA operation example 1, if AP1 allocates a part of the wireless resources of the TXOP to AP2 and then allocates another part of the wireless resources of the TXOP to AP3, AP3 and the STAs under it will set the basic NAV in frame exchanges with AP2 and the STAs under it. Therefore, if AP2 sets the time to cover until the end of the TXOP of AP1 in the Duration / ID field or the TXOP field, since the basic NAV is set, AP3 and the STAs under it cannot transmit. Thus, if AP2 sets the Duration / ID field or the TXOP field to cover only the time allocated by AP1, and the STAs connected to AP2 also make settings according to AP2, AP3 and the STAs under it can transmit.

[0151] Next, an AP / STA operation example, which is a modified example of STA operation example 1, will be described. The AP / STA operation example defines not only the operation of the STA but also the operation of the AP.

[0152] <AP / STA Operation Example: Applying intra-BSS NAV to Frames within an ESS> In this operation example, when a frame within the same ESS is received, intra-BSS NAV is set. In this case, the NAV setting condition is an extension of the part that was the local BSSID in the aforementioned normal intra-BSS NAV setting condition to all BSSIDs within the ESS. This NAV setting condition may be applied only to the STAs connected to the AP, or it may be applied to both the AP and the STAs connected to it. Here, an operation example of setting intra-BSS NAV for both the AP and the STA will be described. Assume that the STA can respond to the TF from its own AP when only intra-BSS NAV is set. Assume that the AP can respond to the MAP TXS TF from other APs within the same ESS when only intra-BSS NAV is set.

[0153] Figure 19 is a diagram for explaining an example of the AP / STA operation example. AP1 or a STA under it transmits a CTS-to-self frame to AP2 and the STAs under it at the beginning of a frame exchange, for example, to protect the TXOP. AP2 and the STAs 21 and 22 under it determine from the CTS-to-self frame that AP1 is an AP within its own ESS and set intra-BSS NAV. AP2 receives the MAP TXS TF from AP1. When AP2 determines that the MAP TXS TF is a frame within its own ESS and only intra-BSS NAV is set, it ignores it, transmits a TXP RES to AP1, and transmits the TF to the STAs 21 and 22 under it. Since the TF is a frame from AP2 within the same BSS, when only intra-BSS NAV is set, STAs 21 and 22 ignore it and transmit Data1 and Data2 to AP2 respectively.

[0154] The setting condition of intra-BSS NAV based on the received power level described in STA operation example 1 may be added to the AP / STA operation example.

[0155] In the case of the AP / STA operation example, even if AP1 allocates some wireless resources to AP2 and then continues to allocate some wireless resources of the TXOP to another AP3, problems such as those in STA operation example 1, where AP2 sets the basic NAV until the end of AP1's TXOP and transmission cannot be performed by AP3 and its subordinate STAs, do not occur. Therefore, although it may be done in the same way as STA operation example 1, in the AP / STA operation example, AP2 sets the time to cover until the end of AP1's TXOP in the Duration / ID field or the TXOP field, and the STAs subordinate to AP2 also make settings according to AP2 so that AP3 and its subordinate STAs can transmit.

[0156] Also, in the AP / STA operation example, as shown in FIG. 19, even if the shared source AP, AP1, transmits a CTS-to-self frame at the beginning of a frame exchange to protect the TXOP before transmitting the MAP TXS TF, the intra-BSS NAV is set, and STA21 and STA22 can respond to the subsequent TF from AP2 without problems.

[0157] <STA operation example 2: In a frame sharing the TXOP with another AP, the NAV is not set> In STA operation example 2, the STA has two NAVs, an intra-BSS NAV and a basic NAV. Normally, when the STA receives a frame in which an AP shares a part of the radio resources of the TXOP with another AP, the STA sets the basic NAV, or sets the intra-BSS NAV if the RA is set to its own AP. However, in STA operation example 2, the STA does not set those NAVs. Whether the STA has received a frame in which an AP shares a part of the radio resources of the TXOP with another AP can be determined by the frame type. For example, if the frame is a MAP TXS TF which is a kind of trigger frame as in the previous example, the Type subfield of the Frame Control field is a control frame, the Subtype subfield is a trigger frame, and the Trigger Type subfield of the Common Info field is a MAP TXS variant. By looking at the type of this variant, the frame type can be determined, and a decision can be made to set / not set the NAV according to the determination result.

[0158] Figure 20 is a diagram for explaining an example of STA operation example 2. When STA21 and STA22 detect that the frame type is MAP TXS TF, they determine that the frame is a frame that does not set the NAV. Therefore, when AP2 then transmits a TXS RSP to AP1 and STA21 and STA22 receive it, they set the intra-BSS NAV as in the conventional case. For the TF that AP2 then transmits to STA21 and STA22, if only the intra-BSS NAV is set, STA21 and STA22 can respond and transmit to the TF.

[0159] In STA operation example 2, only the frame type, that is, whether it is MAP TXS TF or not, is used for the determination of NAV setting. The determination of whether it is from an AP within the same ESS or whether the received frame is addressed to the local AP (whether the RA is set to the local AP or the local AP is specified in the AID12 subfield) is not necessary for NAV setting. Since it is only necessary to simply check the frame type, the criteria for NAV setting can be simplified.

[0160] Since NAV is not set by MAP TXS TF, TXOP protection cannot be achieved. However, if there is a subsequent TXS RSP transmission from the local AP, STA21 and STA22 will set the intra-BSS NAV by that transmission. Also, when a part of the TXOP is allocated to another AP and that other AP transmits a TXS RSP, STA21 and STA22 will set the basic NAV by that transmission. Therefore, the TXOP of the AP that transmitted MAP TXS TF will ultimately be protected.

[0161] Note that when MAP TXS TF is transmitted to multiple APs and the response TXS RSP becomes a MU transmission to the AP that transmitted MAP TXS TF (this will be referred to as inter-AP MU), it is conceivable that STA21 and STA22 will set the basic NAV once. This is the case when assuming the operation where STA21 and STA22 set the basic NAV because the ESS color in the header of the physical packet of inter-AP MU is not the BSS color of the local BSS. If STA21 and STA22 set the basic NAV, they will not be able to transmit a response to the subsequent TF from AP2.

[0162] As one way to avoid this, when the STA sets the intra-BSS NAV, for example, by receiving the TF from its own AP after the SIFS from the end time of the basic NAV setting, it is conceivable to cancel the immediately preceding basic NAV (set the NAV value to 0). If the basic NAV has been set previously and the STA receives an inter-AP MU during that period and updates the basic NAV again, and then sets the intra-BSS NAV after the SIFS from the end time of the updated NAV, the STA does not cancel the basic NAV. That is, the STA can cancel the basic NAV only when a new basic NAV is set at the SIFS immediately preceding the physical packet for which the intra-BSS NAV is set.

[0163] Alternatively, another way to avoid this is that when the STA can determine from the ESS color in the header of the physical packet that it has received a frame within the same ESS, it sets the intra-BSS NAV instead of the basic NAV.

[0164] Alternatively, yet another avoidance method is that when the STA receives an inter-AP MU physical packet immediately after receiving the MAP TXS TF, it does not set the NAV in the same way as when it receives the MAP TXS TF (in this case, it does not set the basic NAV in particular).

[0165] In STA operation example 2, when AP1 allocates some wireless resources to AP2 and then continues to allocate some wireless resources to other APs, similar to the case of STA operation example 1, the basic NAV will be set in frame exchanges in other BSSs. Therefore, to avoid this, each AP sets the Duration / ID field or the TXOP field to cover only the time allocated by the shared source AP. Also, the STAs connected to each AP make settings according to that AP.

[0166] Also, in STA operation example 2, when, for example, the CTS-to-self frame is transmitted at the beginning of frame exchange in order for the shared source AP, AP1, to protect the TXOP before transmitting the MAP TXS TF, the CTS-to-self frame has only the RA in the address field, and since the RA is AP1, STA21 and STA22 set the basic NAV and then cannot respond to the TF from AP2. Regarding STA operation example 2, since the purpose is to enable the STA to perform a desired transmission under the MAP with as simple NAV setting conditions as possible, as a solution to this problem, for example, it is compatible to prohibit the transmission of the CTS-to-self frame in the AP that transmits the MAP TXF TF, as described as a solution to the same problem in STA operation example 4 described later. However, other solutions in STA operation example 4 may also be applied.

[0167] <STA operation example 3: When the frame shares the TXOP with other APs and the own AP is included in the TXOP sharing target, the NAV is not set> In STA operation example 3, similar to STA operation example 2, the STA has two NAVs, the intra-BSS NAV and the basic NAV. However, different from STA operation example 2, the STA checks whether the sharing target is the own AP in addition to the frame type.

[0168] FIG. 21 is a diagram for explaining an example of STA operation example 3. In this example, AP1 is transmitting the MAP TXS TF to AP2 and other APs. Therefore, the RA of the MAP TXS TF is the broadcast address. When STA21 and STA22 receive this MAP TXS TF, they check whether the own AP is the allocation target. That is, STA21 and STA22 check whether AP2, which is the own AP, is specified in any of the AID12 sub-fields in the User Info field of the received MAP TXS TF. If the received frame is the MAP TXS TF and the own AP is specified, STA21 and STA22 do not set either the basic NAV or the intra-BSS NAV. If this condition is not met, STA21 and STA22 perform the normal NAV setting.

[0169] For example, when STA21 and STA22 receive a MAP TXS TF, if they cannot confirm that their own AP is specified in the MAP TXS TF, they set the basic NAV. If the RA of the MAP TXS TF is set to AP2 (i.e., when it is assigned only to AP2), STA21 and STA22 may set the intra-BSS NAV according to the normal NAV setting procedure. Therefore, when the received frame is a MAP TXS TF and the RA is a unicast address, STA21 and STA22 set the NAV according to the normal procedure. That is, if the RA is their own AP, STA21 and STA22 set the intra-BSS NAV, and if the RA is another AP, they set the basic NAV. When the received frame is a MAP TXS TF and the RA is a broadcast address, STA21 and STA22 check whether their own AP is assigned. If their own AP is assigned, they do not set the NAV, and if they cannot confirm the assignment of their own AP, they set the basic NAV.

[0170] In STA operation example 3, it is not necessary to confirm transmission from an AP within the same ESS (i.e., confirm the TA of the MAP TXS TF), but depending on the confirmation and setting of the RA, further confirmation of the destination may be required.

[0171] In STA operation example 3, when the received frame is a MAP TXS TF, addressed to multiple APs and assigned to its own AP, the TXOP cannot be protected by the frame. Subsequently, although the TXS RSP transmission from its own AP is expected to be an inter-AP MU transmission, in that case, it is conceivable that STA21 and STA22 first set the basic NAV. This is the same situation as presented in STA operation example 2. If STA21 and STA22 set the basic NAV, they cannot subsequently respond to the TF from AP2.

[0172] Therefore, in order to avoid this, similar to what was presented in STA operation example 2, for example, cancel the newly set basic NAV immediately before setting the intra-BSS NAV, or when it can be determined from the ESS color of the header of the received physical packet that the physical packet was transmitted from the same ESS, set the intra-BSS NAV instead of the basic NAV, or do not set the NAV for the inter-AP MU immediately after the MAP TXS TF where the NAV was not set, and so on. In any case, when transmissions from the self-AP to within the self-BSS continue to occur, the intra-BSS NAV is set on the STA side thereby, or on the STA side, since it becomes the target of the AP's transmission and has a timer, the transmission of the response frame to the AP is suppressed only, and the radio resources can be protected during the TXOP period assigned to the self-AP. Furthermore, when it is subsequently assigned only to other APs, the basic NAV will be set and the radio resources can be protected. Since only the intra-BSS NAV is set for STA21 and STA22 when receiving the TF from AP2, they can transmit a response to the TF.

[0173] In STA operation example 3, when AP1 assigns a part of the TXOP radio resources to AP2 and then assigns a part of the TXOP radio resources to other APs, similar to the case of STA operation example 1, the basic NAV will be set in other BSSs. Therefore, each AP sets the Duration / ID field, or the TXOP field, to cover only the time assigned to the shared source AP, and the STAs connected to each AP also make settings according to that AP.

[0174] In STA operation example 3 as well, if a frame exchange is performed in advance to protect the entire TXOP, such as when the shared source AP, AP1, transmits a CTS-to-self frame at the beginning of the frame exchange, there may be a problem that STA21 and STA22 set the basic NAV and cannot respond to the subsequent TF from AP2. To avoid this, a solution method similar to STA operation example 4 described later may be applied.

[0175] <STA Operation Example 4: When receiving a frame that shares the TXOP with other APs and the own AP is included in the TXOP sharing destination, set the intra-BSS NAV> In STA Operation Example 4, when the STA receives a frame in which the sharing source AP allocates a part of the wireless resources of the TXOP to the sharing destination AP and the AP connected to the STA is allocated as the sharing destination of the part of the wireless resources, the STA sets the intra-BSS NAV. In STA Operation Example 3, when the received frame satisfies the same conditions, the basic NAV is not set, but in STA Operation Example 4, the intra-BSS NAV is set.

[0176] FIG. 22 is a diagram for explaining an example of STA operation example 4. The AP1 that has acquired the transmission right transmits a MAP TXS TF that allocates some radio resources to AP2 and other APs. When this MAP TXS TF allocates some radio resources to a plurality of APs, a broadcast address is set for the RA as in FIG. 21 of STA operation example 3. Therefore, when STA21 and STA22 determine that the received frame is of the frame type MAP TXS TF, they next check whether their own AP, AP2, is the target of allocation. That is, STA21 and STA22 check whether AP2 is specified in any of the AID12 sub-fields in the User Info field of the MAP TXS TF. If AP2 is specified, STA21 and STA22 set the intra-BSS NAV. If the conditions for setting this intra-BSS NAV are not met, STA21 and STA22 perform normal NAV setting, that is, set the basic NAV. Note that when the MAP TXF TF is transmitted only to AP2 and the RA is set to AP2, STA21 and STA22 set the intra-BSS NAV according to the procedure of normal NAV setting. Therefore, as a procedure, when the received frame is MAP TXS TF, if the RA is a unicast address, STA21 and STA22 perform NAV setting according to the normal procedure. That is, if the RA is their own AP, STA21 and STA22 set the intra-BSS NAV, and if the RA is another AP, they set the basic NAV. When the received frame is MAP TXS TF and the RA is a broadcast address, STA21 and STA22 check whether their own AP is allocated. If it can be confirmed, set the intra-BSS NAV, and if it cannot be confirmed, set the basic NAV.

[0177] When STA21 and STA22 receive a MAP TXS TF that allocates radio resources to their own AP, AP2, they set the intra-BSS NAV. Therefore, STA21 and STA22 can then respond to the TF from AP2.

[0178] Even in STA operation example 4, similar to STA operation example 3, it is not necessary to confirm transmission from an AP within the same ESS (i.e., confirm the SA of MAP TXS TF), but depending on the confirmation and setting of the RA, further confirmation of the allocation destination may be required.

[0179] In STA operation example 4, different from STA operation example 3, even when the received frame is MAP TXS TF, addressed to multiple APs, and there is a wireless resource allocation to the local AP, the TXOP can be protected by the frame. Subsequently, the TXS RSP transmission from the local AP is expected to be an inter-AP MU transmission. In that case, if STA21 and STA22 determine that the BSS color in the header of the MU packet is different from their own BSS, they will set the basic NAV. This is the same situation as presented in the aforementioned STA operation example 2 or STA operation example 3.

[0180] Therefore, as a method to avoid this, there are the methods adopted in STA operation example 2 and STA operation example 3. For example, the STA sets the intra-BSS NAV in the TF, but there is a method of canceling the newly set basic NAV immediately before that. Alternatively, there is a method of putting the BSS color in the header of the physical packet where it is usually not put in inter-AP communication. Or there is a method of separately providing a field for putting the ESS color and setting the intra-BSS NAV instead of the basic NAV when it can be determined that the communication is within the same ESS. Or when the intra-BSS NAV set in the MAP TXS TF and the basic NAV set by the TXS RSP are in the same period (i.e., the end points of the NAV are the same), there is a method of setting the NAV set by the TXS RSP to the intra-BSS NAV instead of the basic NAV.

[0181] In the example of FIG. 22, for the physical packet (storing TXS RSP) that determines whether to replace the type of NAV from basic NAV to intra-BSS NAV, the physical packet (storing MAP TXS TF) that sets the intra-BSS NAV to be compared comes first. However, as the physical packet that sets the intra-BSS NAV to be compared, a physical packet that stores TF and comes after the physical packet that stores TXS RSP may be used. In that case, when the basic NAV set by TXS RSP and the intra-BSS NAV (timer to be held when allocated only to the own STA) set by the TF that allocates radio resources to the STA of the own BSS are in the same period (i.e., the end points of the NAV are the same), the NAV set by TXS RSP is changed from basic NAV to intra-BSS NAV. When the periods set in this way are the same, when changing the basic NAV to intra-BSS NAV, the above-mentioned constraints immediately before or immediately after may be combined. In that case, in order to determine immediately before or immediately after, it is used whether the interval between two frames is, for example, the frame interval of SIFS. In order to ensure that the basic NAV is rewritten to intra-BSS NAV only when the immediately preceding one is basic NAV, STA21 and STA22, when newly setting the basic NAV, store, for example, the start point (end point of the physical packet) and the end point of the NAV in a temporary memory (for example, memory 94 in FIG. 2), and then determine whether the difference between the start point of the physical packet when setting the intra-BSS NAV (or the timer to be held) and the start point of the NAV is SIFS, and whether the end point of the NAV becomes the same when the difference is SIFS. If these two conditions are satisfied, STA21 and STA22 may not set the basic NAV, and if not satisfied, may set the basic NAV.Alternatively, when STA21 and STA22 newly set the basic NAV, for example, they store the end time of the NAV in temporary memory. When the inter-frame interval with the next physical packet is SIFS or more (processing time for comparison and setting may be added), while deleting the stored information, they finalize the setting of the basic NAV. If information remains for comparing the end time of the inter-BSS NAV (or the timer to be held) of the next physical packet, they determine whether the end time of the NAV is the same. If it is the same, they do not set the basic NAV; if it is not the same, they may set the basic NAV. In any case, a mechanism for holding information in some temporary memory is necessary. By doing so, during the TXOP period allocated by the own AP, the allocated radio resources can be protected. Furthermore, when only other APs allocate some of the radio resources of the TXOP later, the basic NAV will be set, and the allocated radio resources can be protected.

[0182] In this STA operation example 4, when AP1 allocates some radio resources to AP2 and then continues to allocate some radio resources to other APs, similar to the case of STA operation example 1, the basic NAV will be set in other BSSs. Therefore, each AP sets the Duration / ID field and the TXOP field to cover only the time allocated by the shared source AP, and the STAs connected to each AP also make settings according to that AP.

[0183] Also in this STA operation example 4, when the shared source AP, AP1, sends a CTS-to-self frame at the beginning of frame exchange and then allocates a part of the radio resources to AP2, STA21 and STA22 will set the basic NAV and will not be able to respond to the TF even if they receive the TF from AP2 later.

[0184] In the case of the first solution, when the received frame is a CTS-to-self frame transmitted from an AP within the same ESS, for example, STA21 and STA22 set the intra-BSS NAV. If only some of the APs capable of MAP operation within the same ESS are limited, when STA21 and STA22 receive a CTS-to-self frame transmitted from an AP in the MAP candidate set, they set the intra-BSS NAV.

[0185] The second solution is that STA21 and STA22 first set the basic NAV with a CTS-to-self frame. However, if the same sender allocates the wireless resources of the TXOP to its own AP immediately after that, i.e., after the SIFS, they set the intra-BSS NAV and cancel the previous basic NAV. The method of canceling the once-set basic NAV is the same as the method of canceling the basic NAV by the aforementioned TXS RSP. Alternatively, the transmission of the CTS-to-self frame before the transmission of a frame that allocates some of the wireless resources of the TXOP to another AP is prohibited.

[0186] The third solution is to prohibit the transmission of the CTS-to-self frame before the transmission of the TXOP sharing frame. As a result, STA21 and STA22 are prohibited from setting the basic NAV and can respond to the TF when they receive the TF from AP2.

[0187] The fourth solution is to use a CTS frame (CTS-to-ESSself frame) with the RA set to a multicast address for the AP group within the ESS instead of the CTS-to-self frame. In this case, it is necessary to inform in advance each STA connected to each AP of the multicast address for the AP group within the ESS. Also, when the STA receives a CTS frame, if the RA is set to the multicast address for the AP group within the ESS (i.e., it is a CTS-to-ESSself frame directed to the self-ESS), the intra-BSS NAV should be set. However, if the entire TXOP is protected in advance, not limited to the CTS-to-self frame, such as when AP1 exchanges frames first with the STA connected to AP1, STA21 and STA22 will set the basic NAV due to their frame exchanges, and in these methods, they cannot respond to the TF from the self-AP after the wireless resources are allocated to the self-AP. To solve this most simply, it is conceivable that AP1 sets a limit when allocating a part of the wireless resources of the TXOP to other APs. For example, even if the BSS configured by the source AP for sharing is the self-BSS, when the source AP uses the TXOP, or when the source AP transmits a TF to the STAs within the BSS configured by the source AP itself and those STAs transmit to the source AP, and those STAs use the TXOP, the periods of the TXOP used by the source AP and the destination AP for sharing are made the same. Alternatively, after using the TXOP for the period allocated to the destination AP, or if a part of the wireless resources of the TXOP is allocated to the destination AP, then the destination AP can be decreased but not increased hereafter. By doing so, it is possible to avoid the situation where the STAs under each AP cannot respond to the TF from the self-AP due to the basic NAV.

[0188] <STA operation example 5: When it is determined that wireless resources are allocated to the self-STA by the TF from the self-AP within the period of the NAV set by the frame sharing the TXOP from the AP, the NAV is ignored and a response is made)> STA operation example 5 is an operation example that can handle the case where the STA has only one NAV. The STA sets the NAV when it receives a frame in which the shared source AP shares a part of the wireless resources of the TXOP with its own AP. However, if the STA receives a frame (MAP TXF TF) in which the shared source AP shares a part of the wireless resources of the TXOP with its own AP after receiving it (exactly when the physical packet storing it ends on the wireless medium), and the TF is received from its own AP within a fixed time from that time, and the STA is assigned by the TF, the STA ignores the NAV and responds. Also, within the TXOP specified by the TF from its own AP (actually, a part of the TXOP of the shared source AP assigned from the shared source AP), it is possible to continue the operation of ignoring the NAV and responding to the TF. The fixed time is, for example, the sum of the occupancy time of the frame in which the shared destination AP transmits a response to the sharing notification to the shared source AP and the inter-frame intervals required before and after it. For example, when the occupancy time of the frame varies, the occupancy time of the frame is set to its expected maximum value or the like. In FIG. 23, the fixed time needs to ensure at least the time from when AP2 transmits the TXS RSP until it is determined that AP2 has started transmitting the TF. If each inter-frame interval is SIFS and the start of transmission of the TF can be determined from the TXS RSP by SIFS + slot time (= PIFS), then at least 2 × SIFS + the occupancy time of the physical packet storing the TXS RSP + slot time is the fixed time. The occupancy time of the physical packet storing the TXS RSP varies if the transmission rate and frame length are variable, so for example, the expected maximum time is used. For example, this fixed time is defined by a value.

[0189] Alternatively, instead of within the fixed time, the STA may ignore the NAV and respond on the condition that there is no free time of SIFS or more during the period when the CCA recognizes that the channel is idle (i.e., the medium is not being used) (STA operation example 5a).

[0190] FIG. 23 is a diagram for explaining an example of STA operation example 5. When AP1 transmits a MAP TXS TF to AP2, and after the SIFS, AP2 transmits a TXS RSP to AP1, and further after that SIFS, AP2 transmits a TF to STA21 and STA22, the time between the MAP TXS TF and the TF is the sum of 2×SIFS and the occupancy time of the physical packet storing the TXS RSP. For example, if the occupancy time of the physical packet storing the TXS RSP is defined as fixed or defined as the maximum value assumed, and if a TF is received from its own AP within the fixed time of the MAP TXS TF, then STA21 and STA22 can respond to the TF. Also, since all physical packets are exchanged at SIFS intervals, if all of them can be observed, there will be no CCA time left that is more than SIFS, and the STA should be able to respond when it receives a TF from its own AP if it satisfies that condition. Note that when the occupancy time of the physical packet storing the TXS RSP is within a fixed time, if the own AP first reallocates some radio resources to other STAs and then reallocates them to the own STA, the condition within the fixed time is not satisfied, and thus a situation may occur where the STA cannot respond to the TF. This situation cannot occur in STA operation example 5a.

[0191] Alternatively, when the own AP responds to a frame that shares some radio resources of the TXOP with another AP (since the decoding at the STA cannot be expected for the MU physical packet, in order to grasp whether the own AP has responded in this way, it is limited to the case where the response frame is SU-transmitted), or when the own AP is allocated in a frame that shares some radio resources of the TXOP with another AP, STA21 and STA22 may be made to be able to respond to the TF from the own AP by ignoring the NAV within that TXOP (STA operation example 5b).

[0192] Alternatively, as described in STA operation example 4, if the end point of the NAV by the frame that shares a part of the radio resources of the TXOP with the own AP is the same as the end point of the NAV set by the own AP or the timer held within the subsequent fixed time, STA21 and STA22 may ignore the NAV and respond to the TF from the own AP (STA operation example 5c). The method related to determining whether the end points are the same in this case is the same as that described in STA operation example 4.

[0193] When AP1 allocates a part of the radio resources to a certain AP and then further allocates a part of the radio resources of the TXOP to another AP, in STA operation example 5 (determining whether to ignore the NAV based on whether the TF addressed to the own STA arrives within the fixed time of the MAP TXS TF), the STA cannot cancel the NAV and cannot respond to the TF from the own AP when the fixed time is exceeded. To avoid this, for example, after the source AP that shares the resources allocates a part of the radio resources of the TXOP to the destination AP that shares the resources, the destination AP that shares the resources cannot be increased hereafter, although it can be decreased.

[0194] In STA operation example 5a (when conditional on the presence or absence of a CCA idle period longer than the SIFS), if all physical packets can be observed, there is no problem that the STA cannot respond to the TF from the own AP. Also, in STA operation example 5b (ignoring the NAV when the own AP can determine that it has been allocated a part of the radio resources of the TXOP from another AP) and STA operation example 5c (when determining using the end point of the NAV), there is no problem that the STA cannot respond to the TF from the own AP.

[0195] Even if the transmission of the CTS-to-self frame preceded the transmission of a frame that shares some wireless resources of the TXOP with another AP, in STA operation example 5 (determining whether to ignore the NAV based on whether a TF addressed to the self-STA arrives within the fixed time of the MAP TXS TF), STA21 and STA22 can respond to the TF from the self-AP if, for example, the fixed time includes the occupancy time of the physical packet storing the CTS-to-self frame at the fixed time and also the SIFS before the transmission of the frame that shares some wireless resources of the TXOP with another AP. If the inter-frame interval between the CTS-to-self frame before the MAP TXS TF is SIFS, the fixed time is set so as to cover up to the time required for CTS-to-self frame transmission + SIFS. The fixed time requires 3×SIFS + the occupancy time of the physical packet storing CTS-to-self + the occupancy time of the physical packet storing TXS RSP + the slot time. Taking into account that there is also the transmission of CTS-to-self, a longer value can be defined as the fixed time. However, in special cases, STA21 and STA22 cannot respond to the TF from the self-AP. For example, when a frame exchange is carried out between the sharing source AP and other STAs to protect the entire TXOP before the transmission of a frame that shares some wireless resources of the TXOP with another AP, STA21 and STA22 cannot respond to the subsequent TF from the self-AP. To solve this, there is the same avoidance method as in STA operation example 4 in such cases. Note that in STA operation example 5a (when the condition for responding by ignoring the NAV is the presence or absence of a CCA idle period of SIFS or more), STA operation example 5b (ignoring the NAV when it can be determined that the self-AP has been allocated some wireless resources of the TXOP from another AP), and STA operation example 5c (determining whether to ignore the NAV using the end point of the NAV), in such cases, there is no problem that STA21 and STA22 cannot respond to the TF from the self-AP.

[0196] <STA Operation Example 6: Three NAVs> In STA operation example 6, in addition to the conventional basic NAV and intra-BSS NAV, a third NAV, ESS NAV, is newly introduced to the STA. The ESS NAV is a NAV that is set when it is determined that the received frame / physical packet is not a frame / physical packet within its own BSS (i.e., the intra-BSS NAV is not applicable), but is a frame / physical packet within the same ESS. A STA having the conventional two NAVs sets the basic NAV when the received frame / physical packet is not a frame / physical packet within its own BSS. In STA operation example 6, the STA adds the identification of whether the frame / physical packet outside its own BSS is within the same ESS, and sets the ESS NAV when it is determined that the frame / physical packet outside its own BSS is within the same ESS, and sets the conventional basic NAV when it is not so determined. FIG. 24 is a flowchart showing an example of the NAV setting of the STA in STA operation example 6. The STA determines whether the received frame / physical packet is a frame / physical packet within its own BSS (step S102). When the STA determines that the received frame / physical packet is a frame / physical packet within its own BSS, it sets the intra-BSS NAV (step S104). When the STA determines that the received frame / physical packet is not a frame / physical packet within its own BSS, it determines whether the received frame / physical packet is a frame / physical packet within its own ESS (step S106). When the STA determines that the received frame / physical packet is a frame / physical packet within its own ESS, it sets the ESS NAV (step S108). When the STA determines that the received frame / physical packet is not a frame / physical packet within its own ESS, it sets the basic NAV (step S110).

[0197] The determination used for the setting of the ESS NAV is basically the same as the method for setting the aforementioned intra-BSS NAV. The information used for the setting determination of the intra-BSS NAV in STA operation example 6 is different from the information used for the setting determination of the aforementioned intra-BSS NAV.

[0198] In STA operation example 6, if the STA can receive a physical packet, decrypt it, and extract the address fields from the MAC frame stored in the physical packet, it determines whether the received frame is within its own ESS according to those address fields. Or, if there is no TA but there is an RA in the MAC frame, it determines whether the received frame is within its own ESS based on the relationship between the value described in the RA and the MAC address of the TXOP holder that acquired the transmission right previously. The STA has previously obtained from the connected AP the MAC addresses of other APs within its own ESS (i.e., the BSSIDs of other BSSs within its own ESS).

[0199] Also, when the STA cannot decode the received physical packet, it determines whether the received physical packet is from communication within the same ESS based on the header of the physical packet, and sets the ESS NAV accordingly. For this determination, for example, there is a method of using the BSS color as described above. Alternatively, the ESS color value may also be put in the BSS Color field as described above. Alternatively, when defining a new physical packet with an additional ESS Color field separate from the BSS Color field, the determination may be made based on the value of the ESS Color field. In this case, the value of the TXOP field in the physical header is used as the value for setting any of the NAVs. In order to identify that the received packet is a physical packet used for communication within the same ESS without specifically defining the ESS color in the BSS Color field, the STA needs to know not only the BSS color of its own conventional BSS but also the BSS colors of other BSSs within the same ESS. The STA may obtain this information from the connected AP. In order for the AP to know the BSS colors of other BSSs within the same ESS, it may receive notifications of the BSS colors of other BSSs within the same ESS from other APs within the same ESS, for example, via beacon frames or action frames used between APs, as a preliminary step. For example, if an AP within the same ESS can notify the BSS colors used by multiple other APs within the same ESS, the AP does not need to obtain the BSS colors from other APs individually, and efficiency can be improved.

[0200] When the ESS color is specially defined and can be notified within the BSS Color field, it is necessary to check whether the BSS color of the local BSS is based on the BSS Color field value (step S102). If the BSS color of the local BSS is not set in the BSS Color field, it is necessary to check whether the ESS color of the local ESS is set in the BSS Color field (step S106). In the case of a new physical packet with the ESS Color field provided separately from the BSS Color field, first, it is necessary to determine whether the BSS color of the local BSS is set in the BSS Color field (step S102). If it is determined that the BSS color of the local BSS is not set, then it is necessary to determine whether the ESS color of the local ESS is set in the ESS Color field (step S106). This ESS color also needs to be determined by some method among the APs within the same ESS, shared, and made known to the STAs connected to each AP. Then, if the basic NAV is not set, the STA can respond to the TF from its own AP.

[0201] Figure 25 is a diagram for explaining an example of this STA operation example 6. STAs 21 and 22 connected to AP2 receive the MAP TXS TF transmitted by AP1 to AP2 and other APs. In this case, the RA of the MAP TXS TF is a broadcast address, and the TA is set to AP1. Therefore, STAs 21 and 22 detect that the TA of the MAP TXS TF is not the BSSID of the local BSS (i.e., the MAC address of its own AP), but one of the BSSIDs of other BSSs that can be recognized as being within the same ESS (i.e., the MAC address of an AP other than its own AP that can be recognized as being within the same ESS). Therefore, STAs 21 and 22 set the ESS NAV using the TXOP field value of the physical header of the physical packet when the physical packet stored with the MAP TXS TF ends on the wireless medium.

[0202] After that, as a response to MAP TXS TF, AP2 sends TXS RSP to the MU for AP1. At this time, for example, ESS color is put into the BSS Color field of the physical header of the physical packet sent by AP2 to the MU. For example, when the AP performs inter-AP communication, if there is a BSS Color field in the physical packet to be used, it is determined that ESS color is put into the field. STA21 and STA22 detect that the ESS color of their own ESS, rather than the BSS color of their own BSS, is put into the BSS Color field of the physical header of the TXS RSP sent to the MU, and extract the TXOP field value of the physical header of the physical packet storing this TXS RSP. When the NAV set by the TXS RSP is longer than the ESS NAV set by the MAP TXS TF, STA21 and STA22 overwrite the ESS NAV with the TXOP field value of the physical header of the physical packet storing the TXS RSP. For example, AP2 sets the same value as the NAV set by the MAP TXS TF, that is, a value covering up to the end point of the TXOP obtained by AP1, in the Duration / ID field of the TXS RSP and the TXOP field of the physical packet. In such a case, the ESS NAV set by STA21 and STA22 is set by the MAP TXS TF up to the end point of the TXOP obtained by AP1. Therefore, there is no need to overwrite the ESS NAV by the MAP TXS TF.

[0203] After that, when STA21 and STA22 receive the TF from AP2, assume that only ESS NAV is set in STA21 and STA22. When STA21 and STA22 receive the TF from AP2, after recognizing that the TF is a frame within its own BSS, since the self STA is not the TXOP holder while receiving the TF, it sets the intra-BSS NAV. In this case, STA21 and STA22 (and further AP2 as well) recognize that the TF for which the TXOP holder has set the ESS NAV is the TF from AP1. Since the ESS NAV and intra-BSS NAV are set when receiving the TF, but the basic NAV is not set, STA21 and STA22 can transmit a frame as a response to the TF.

[0204] In the case of STA operation example 6, even when AP1 allocates a part of the wireless resources of the TXOP to its own BSS or other APs, and then AP2 or a plurality of APs including AP2 allocate a part of the wireless resources of the TXOP, for STA21 and STA22, during the time when a part of the wireless resources of the TXOP is allocated to other APs, the ESS NAV will be set instead of the conventional basic NAV. Therefore, there is no problem in setting the Duration / ID field and the TXOP field to protect the entire TXOP in AP1 and the AP (including AP2) to which a part of the wireless resources of its TXOP is allocated. That is, even if STA21 and STA22 receive the TF from AP2 during that period, they can transmit a response.

[0205] Also, even if AP1 first performs an operation to protect the TXOP with a CTS-to-self frame or the like, STA21 and STA22 will set the ESS NAV instead of the conventional basic NAV, and they can transmit a response even if they receive the TF from AP2 later.

[0206] Figure 26 shows the settings under which the three types of NAV, namely basic NAV, intra-BSS NAV, and ESS NAV, allow a STA to respond to a TF from its own AP (Trigger frame response @ non-AP STA). Figure 26 also describes the conditions under which a response can be transmitted when an AP, as shown in the previous AP operation example 4, is allocated a part of the radio resources of the TXOP from another AP (MAP response @ AP). On the STA side, communication between MAPs where basic NAV was conventionally set is replaced by ESS NAV, enabling the STA to respond to TF transmissions from its own AP.

[0207] (1) When basic NAV, intra-BSS NAV, and ESS NAV are all non-zero (i.e., set), it is impossible to acquire the transmission right, TF response is not possible (i.e., the STA cannot use the allocated radio resources), and MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0208] (2) When basic NAV and intra-BSS NAV are both non-zero (i.e., set) and ESS NAV is zero (i.e., not set), it is impossible to acquire the transmission right, TF response is not possible (i.e., the STA cannot use the allocated radio resources), and MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0209] (3) When basic NAV and ESS NAV are both non-zero (i.e., set) and intra-BSS NAV is zero (i.e., not set), it is impossible to acquire the transmission right, TF response is not possible (i.e., the STA cannot use the allocated radio resources), and MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0210] (4) If the basic NAV is not 0 (i.e., it is set), and both the intra-BSS NAV and the ESS NAV are 0 (i.e., they are not set), obtaining the right to transmit is not possible, the TF response is not possible (i.e., the STA cannot use the allocated radio resources), and the MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0211] (5) If the basic NAV is 0 (i.e., it is not set), and both the intra-BSS NAV and the ESS NAV are not 0 (i.e., they are set), obtaining the right to transmit is not possible, the TF response is possible (i.e., the STA can use the allocated radio resources), and the MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0212] (6) If both the basic NAV and the ESS NAV are 0 (i.e., they are not set), and the intra-BSS NAV is not 0 (i.e., it is set), obtaining the right to transmit is not possible, the TF response is possible (i.e., the STA can use the allocated radio resources), and the MAP transmission is not possible (i.e., the AP cannot use the allocated radio resources).

[0213] (7) If both the basic NAV and the intra-BSS NAV are 0 (i.e., they are not set), and the ESS NAV is not 0 (i.e., it is set), obtaining the right to transmit is not possible, the TF response is possible (i.e., the STA can use the allocated radio resources), and the MAP transmission is possible (i.e., the AP can use the allocated radio resources).

[0214] (8) If the basic NAV, the intra-BSS NAV, and the ESS NAV are all 0 (i.e., they are not set), obtaining the right to transmit is possible, the TF response is possible (i.e., the STA can use the allocated radio resources), and the MAP transmission is possible (i.e., the AP can use the allocated radio resources).

[0215] In this STA operation example 6, similar to STA operation examples 2 to 4, when setting the ESS NAV, the frame type of the received frame may be restricted to MAP TXS TF, or further restrictions may be added such that the self-AP is included in the destination. However, if this is done, when AP1 allocates a part of the radio resources of the TXOP to different APs (or AP groups) in a time-division manner as shown above, the basic NAV will be set in the STAs under the AP allocated later, resulting in the inability to use the allocated radio resources. Also, the basic NAV will be set by the CTS-to-self frame, leading to the inability to use the allocated radio resources. Such problems will occur, and some countermeasures or restrictions as described above will be necessary.

[0216] <STA Operation Example 7: Introduction of a Frame for Truncating the basic NAV> Up to STA operation examples 1 to 6, by changing the operation on the NAV on the STA side from the conventional method, it is possible to respond and transmit to the TF from the self-AP under MAP communication. However, in STA operation example 7, in a situation where it is not possible to respond and transmit to the TF from the self-AP by setting the basic NAV using the conventional method, it is solved by the AP side transmitting a frame that resets the basic NAV to 0. Resetting the NAV, in another expression, is called truncating the TXOP.

[0217] There is a CF-End frame as a frame for resetting the NAV. The CF-End frame is a type of control frame. First, the operation when receiving this conventional CF-End frame will be explained.

[0218] <Conventional Operation of CF-End> Figure 27 shows an example of the format of a CF-End frame. The CF-End frame consists of a Frame Control field, a Duration field, two address fields, and an FCS. The Duration field is set to 0. The first address field is the RA field, which contains the destination address field. In the CF-End frame, a broadcast address is entered. The second address field is the BSSID (TA) field, which contains the MAC address of the STA (including the AP) that transmits the CF-End frame.

[0219] When a STA (including an AP) that manages only one NAV receives a CF-End frame, if the NAV is set, it resets the NAV. Here, specifically, the timing for resetting the NAV is the end of the physical packet that stores the CF-End frame. Note that when an AP (HE AP) compliant with the 802.11ax standard manages only one NAV, the NAV should be reset unless the frame at the time when the set NAV was last updated is from a physical packet within its own BSS and the physical packet that stores the CF-End frame is determined to be from another BSS. Conversely, the NAV should be reset unless the frame at the time when the set NAV was last updated is from a physical packet from another BSS and the physical packet that stores the CF-End frame is determined to be within its own BSS.

[0220] When a STA (including an AP) that manages two NAVs, namely a basic NAV and an intra-BSS NAV, receives a CF-End frame, if it determines that the physical packet that stores the CF-End frame is from another BSS, it resets the basic NAV, and if it determines that the physical packet that stores the CF-End frame is within its own BSS, it resets the intra-BSS NAV.

[0221] To determine whether a physical packet is from within its own BSS or from another BSS, as described above, if the BSS Color field of the physical header of the physical packet can be decoded, or if the MAC frame stored in the physical packet can be decoded, it is determined based on the address field of the MAC frame (and taking into account the past history due to limitations in the address field depending on the frame type). If a CF-End frame can be extracted, it is only necessary to compare whether the MAC address of the AP described in the BSSID (TA) field of the CF-End frame is the same as the MAC address of its own AP to determine whether the physical packet is from within its own BSS or from another BSS.

[0222] As in the above-described STA operation example 6, when a STA that manages three NAVs, namely basic NAV, intra-BSS NAV, and ESS NAV, receives a CF-End frame, if it determines that the physical packet storing the CF-End frame is from within its own BSS, it resets the intra-BSS NAV; if it determines that the physical packet storing the CF-End frame is not from within its own BSS but is from within the same ESS, it resets the ESS NAV; and if it determines that the physical packet storing the CF-End frame is neither from within its own BSS nor from within the same ESS, that is, it is from outside the same ESS, it may reset the basic NAV.

[0223] To determine whether it is within the same ESS, similar to the case of determining whether it is within its own BSS, it may be determined based on the BSS Color field of the physical header of the physical packet or the address field of the MAC frame if the MAC frame stored in the physical packet can be decoded.

[0224] Return to the operation description of STA operation example 7. As STA operation example 7, here, a method is shown that enables a STA that manages two NAVs to respond and transmit a TF from its own AP under the MAP using a frame that resets the basic NAV.

[0225] In the conventional CF-End frame, the MAC address of the local AP is entered in the BSSID(TA) field. Therefore, when the CF-End frame manages two NAVs, it is positioned to be transmitted in order to reset the NAV of its own BSS, that is, the intra-BSS NAV, and the basic NAV remains without being reset. An AP of a certain BSS cannot set the MAC address of another AP in the BSSID(TA) field and transmit it. Also, even if it were possible to set the MAC address of another AP in the BSSID(TA) field and transmit it, in the conventional CF-End frame, when it is determined to be from another BSS, the basic NAV is reset. Thus, this would reset the basic NAV not only for the AP assigned from the sharing source AP and the STA connected to it among the partial radio resources of the TXOP, but also for all the surrounding APs and the STAs connected to them.

[0226] Therefore, in STA operation example 7, a new frame is provided to limit the APs and STAs (reset targets) for which the basic NAV is reset. This frame is conveniently referred to as the CF-End2 frame. The CF-End2 frame is treated as a type of control frame, similar to the CF-End frame. The CF-End2 frame has a different subtype from the CF-End frame.

[0227] The CF-End2 frame may have the same format as the CF-End frame. Set the Duration field to 0. However, different from the CF-End frame, in the CF-End2 frame, the BSSID of the BSS that is the target for resetting the basic NAV is specified in the RA field. Since the RA field is the field for specifying the BSSID, it may be expressed as the BSSID(RA) field instead of the RA field. An STA belonging to a BSS having the same BSSID as the value specified in the RA field performs the operation of resetting the basic NAV if it is set. Even if the intra-BSS NAV is set in the STA of the target BSS, it remains without being reset. For example, limit the transmission of the CF-End2 frame only from the AP. In that case, the transmitting AP sets its own MAC address in the BSSID(TA) field. The receiving STA may reset the basic NAV only when the BSSID(TA) field is the MAC address of its own AP. Alternatively, if the usage of allowing the transmission of the CF-End2 frame targeting the BSS of another AP from an AP within the same ESS is permitted, the receiving STA may also reset the basic NAV when the BSSID(TA) field is the MAC address of another AP within the same ESS. In this case, the STA grasps in advance the MAC addresses of APs other than its own AP within the same ESS by the above-described method or the like. Note that in the CF-End2 frame, it is also possible to use a format in which the BSSID(TA) field is not included and only the BSS to be the target for resetting the basic NAV is specified in the RA field. In this case, the receiving STA resets the basic NAV if the RA field matches the BSSID of its own BSS. However, with this method, any STA can reset the basic NAV of other STAs.Therefore, when the STA that has received the CF-End2 frame confirms the source address of the frame based on the BSSID(TA) field, it may perform an operation to reset the basic NAV only when the BSSID(TA) field meets certain conditions (for example, when it is the local AP as described above, or when it is the AP of the local ESS). To easily determine whether the STA that has received the CF-End2 frame is an AP within the same ESS, a field for adding the identifier of the ESS to the CF-End2 frame, or a field for putting this ESSID instead of the TA field, may be added. The identifier of the ESS is usually the SSID as described above. Therefore, when putting the SSID in the CF-End2 frame which is a control frame, since the SSID has a variable-length structure, it may be put at the end of the frame body as described in the example of AP operation example 1. Alternatively, if a configuration allowing the length information and the SSID value to be put is permitted, the SSID may be put together with the length information. Alternatively, as the identifier of the ESS, a 6-octet fixed ESSID different from the SSID may be defined and this ESSID may be used.

[0228] Figure 28 is a diagram for explaining an example of STA operation example 7. STA operation example 7 is an example in which this CF-End2 frame is used so that the STA can send a transmission response to the TF from the local AP under the MAP. AP1 sends the MAP TXS TFs to AP2 and other APs. Assume that the RA field of the MAP TXS TF is a broadcast address and the TA field is set to AP1. In this case, STA21 and STA22 connected to AP2 can decode the physical packet storing the MAP TXS TF. Even though STA21 and STA22 can extract the MAP TXS TF, since neither the RA field nor the TA field is the BSSID of their own BSS, they determine that the received physical packet is a physical packet of another BSS and set the basic NAV.

[0229] After that, AP2 transmits a TXS RSP to AP1 for the MAP TXS TF from AP1 to the MU. If the BSS color of the BSS configured by AP2 is not described in the physical header of the physically transmitted packet, STA21 and STA22 determine that the physical packet is also a physical packet from another BSS. To determine whether to set the TXOP field value in the physical header as the basic NAV, the period set by the TXOP field value in the physical header is compared with the period of the basic NAV set in the previous MAP TXS TF. If AP2 sets a value obtained by subtracting the occupancy time length of the physical packet storing the SIFS and the TXS RSP frame from the Duration / ID field value in the MAP TXS TF from the TXOP field value in the physical header, that is, if it is set to protect the same period as the TXOP obtained by the MAP TXS TF, since the end time of the basic NAV already set in STA21 and STA22 is the same as the end time of the NAV value indicated by the physical packet storing the TXS RSP frame, STA21 and STA22 do not need to overwrite the basic NAV.

[0230] Next, AP2 reallocates the assigned radio resources to STA21 and STA22. Before that, it transmits a CF-End2 frame to reset the basic NAV of STA21 and STA22. Since the BSS for which the basic NAV is to be reset here is the BSS of AP2, AP2 sets the BSSID of the BSS of AP2 (conveniently represented as BSSID2 in the figure. BSSID2 is the MAC address of AP2) in the RA field of the CF-End2 frame. In the parentheses attached to the CF-End2 frame in Figure 28, the setting status of the RA field, that is, it is shown that it is set to BSSID2, is indicated. AP2 transmits the CF-End2 frame within the radio resources assigned from AP1. STA21 and STA22 receive the CF-End2 frame according to the above description. When they grasp that the BSSID of their own BSS is specified, they reset the set basic NAV to 0 at the end of the physical packet storing the CF-End2 frame.

[0231] After AP2 sends the CF-End2 frame, it sends a TF to reallocate radio resources to STA21 and STA22. The RA of the TF is the broadcast address, and since the TA is set to AP2, STA21 and STA22 determine that the physical packet storing the TF is a physical packet within its own BSS. Moreover, since the received frame is the TF instead of the TXOP holder, it sets the intra-BSS NAV. Because the NAV set by STA21 and STA22 is the intra-BSS NAV, they can respond to the TF, for example, by sending a data frame after the SIFS.

[0232] In Fig. 28, AP2 sends the CF-End2 frame. However, assuming that the MAP TXS TF is also sent to APs other than AP2, after other APs that receive the MAP TXS TF send the TXS RSP in the MU transmission, they similarly send the CF-End2 frame within the allocated radio resources. If the APs are assigned different frequency channels from AP1, each AP can send the CF-End2 frame on the frequency channel it is assigned because the frequencies are different. If the STAs under each AP are waiting on the frequency channel they are assigned, they can receive the CF-End2 frame from their own AP.

[0233] Since the wireless resources have already been allocated, it is more appropriate for the shared destination AP to send a CF-End2 frame, but the source AP1 may also send a CF-End2 frame (the dashed line in Fig. 28). In this case, since AP1 has to reset the basic NAV not only in the BSS (BSSID2) of AP2 but also in the BSSs of other APs, the CF-End2 frame must be able to set multiple BSSIDs. Since the CF-End2 frame is a control frame, taking into account the constraints that the frame length must be fixed or the final frame length can be predicted in advance within the first half of the fields, for example, there is a method of providing a fixed number of RA fields. For example, in the CF-End frame, there was one RA field, while in the CF-End2 frame, four RA fields, for example, an RA1 field, an RA2 field, an RA3 field, and an RA4 field, are provided so that a maximum of four BSSIDs can be specified. When specifying the BSSID, these fields are used in order from the front, and if not all are used, these fields (for example, 6 octets) are filled with all "0"s. If a flexible control frame configuration that can contain length information as described above can be achieved, there is no problem. Alternatively, there is also a method of pre-providing a multicast address that specifies multiple BSSIDs and putting this into the RA. In this case, one field is sufficient. However, when there are multiple combinations of target BSSIDs, it is necessary to specify the corresponding addresses and make them known in advance within the ESS.

[0234] Also, when each AP transmits a CF-End2 frame to the STAs under its own BSS, since the CF-End2 frame is a new frame as described above, conventional STAs do not recognize its subtype and do not perform the expected operation of resetting the basic NAV even if they receive it. Since the Duration field is set to 0, there is no concern that a new basic NAV will be set when a conventional STA receives a CF-End2 frame. This new frame, the CF-End2 frame, is made mandatory for, for example, STAs compliant with the new extension standard. Then, not only when mapping under the new extension standard, but also the CF-End2 frame can be used to reset the basic NAV for the STAs under the target BSS. In this case, within the same ESS, it becomes possible for one AP to transmit a CF-End2 frame to reset the basic NAV in the BSS of another AP. Alternatively, support for the CF-End2 frame under the new extension standard can be made an optional function. In that case, when an STA transmits an association request frame or a re-association request frame to its own AP, it notifies whether it can support the CF-End2 frame, and the AP can grasp in advance which of its subordinate STAs can receive the CF-End2 frame and reset the basic NAV. Alternatively, make MAP an optional function within the new extension standard, and make support for the CF-End2 frame mandatory for STAs compliant with MAP. In this case, when an STA transmits an association request frame or a re-association request frame to its own AP, it notifies whether it can support MAP. The AP grasps which of its subordinate STAs can support MAP and can transmit a CF-End2 frame for the purpose of resetting the basic NAV of the STAs compliant with MAP. If support for the CF-End2 frame is also made mandatory when an STA is compliant with MAP, in order to be able to respond to the TF transmission from its own AP under MAP, it is also possible for another AP to transmit a CF-End2 frame targeting the BSS to which the STA belongs.

[0235] If the CF-End2 frame is to cause the basic NAV to be reset only in MAP-compatible STAs, then, of course, when the AP sends a CF-End2 frame under MAP and then sends a TF, restricting the STAs to which the wireless resources are allocated by the TF to only MAP-compatible STAs, in other words, only the STAs corresponding to the CF-End2 frame, will increase the number of STAs that can respond to the TF and result in the effective utilization of wireless resources.

[0236] In the method using this CF-End2 frame, for example, when AP1 allocates some wireless resources to AP2 and other APs and then allocates some wireless resources to another group of APs, STAs such as STA21 and STA22 under the first allocated AP will receive the MAP TXS TF from AP1 again, or even if they do not receive it, they will receive the TXS RSP from the newly targeted group of APs, and thus reset the basic NAV again and not interfere with communication. Also, in this method, even in a situation where the TXOP is protected in advance by a CTS-to-self frame or the like, the basic NAV protected by the CF-End2 frame can be canceled, so that the STA can respond to the TF from its own AP.

[0237] Note that in STA operation example 7, if the basic NAV is set in advance by a frame unrelated to MAP, it may be overwritten to 0 by the CF-End2 frame, and the STA may ignore the transmission of a frame that it originally had to protect and transmit it, resulting in a possible frame collision. Therefore, STA operation examples 7a, 7b, and 7c for solving this problem are shown below.

[0238] <In STA operation example 7a: Reset the basic NAV only when the basic NAV is set by MAP TXS TF and the CF-End2 frame is received before the end of that NAV> In the first operation example 7a of the solution, by means of a frame (MAP TXS TF according to the previous example) in which the source AP allocates some wireless resources to the destination AP, the STA sets the basic NAV, and resets the basic NAV only when the CF-End2 frame targeted at its own BSS is received before the expiration of the basic NAV, that is, before it ends.

[0239] As an example of the implementation method of the STA operation example 7a, the STA may have a flag indicating whether the basic NAV is set by the MAP TXF TF. When the basic NAV is extended by other frames or physical packets, the STA sets the flag to the off state. Also, if the basic NAV has already been set at the stage of receiving the MAP TXS TF, the STA does not turn on the flag and keeps it in the off state. Moreover, when the CF-End2 frame targeted at its own BSS is received, if the flag is in the on state, the STA resets the basic NAV.

[0240] However, in the STA operation example 7a, when the TXOP is protected in advance by a CTS-to-self frame or the like, or when some wireless resources are allocated to its own AP after some wireless resources are allocated to other APs, the situation is such that the basic NAV is set before the MAP TXS TF. In that case, the STA cannot respond and transmit to the TF from its own AP. Therefore, although it was stated above that if the basic NAV has already been set at the stage of receiving the MAP TXS TF, the STA does not turn on the flag, if the assumed basic NAV set by the MAP TXS TF and the end time of the existing basic NAV are the same, the STA may turn on the flag.

[0241] <STA operation example 7b: Set a value covering the remaining TXOP in the CF-End2 frame, and the STA resets the basic NAV if the basic NAV and the end time are the same> In the second operation example 7b of the solution, the period covering the remaining TXOP in the CF-End2 frame is described. When the STA receives a CF-End2 frame targeted at its own BSS and the remaining period of the set basic NAV is the same as the period described in the CF-End2 frame, that is, if the end time of the remaining TXOP described in the CF-End2 frame is the same as the end time of the set basic NAV, the basic NAV is reset. The period covering this remaining TXOP may be set in the Duration field provided in the same way as in the case of the CF-End frame. Although it is defined that the value "0" is set in the Duration field in the CF-End frame, in the CF-End2 frame, a value of "1" or more can be set in the Duration field. As a result, a conventional STA extracts the value set in the Duration field of the CF-End2 frame as a candidate for NAV setting. However, if it ends at the same time as or earlier than the already set NAV, no NAV overwrite occurs, so there is no impact due to receiving the CF-End2 frame. Alternatively, the Duration field may be left as it is and "0" may be set in the sense that the NAV is reset in the same way as in the CF-End frame. However, a new field, for example, the TXOP Duration field, may be provided separately to describe the remaining TXOP there. The new field in this case is also suitably two octets, the same as the conventional Duration / ID field.

[0242] When the common ancestor AP transmits a CF-End2 frame, the TXOP acquired by the common ancestor AP is recognized by the frames transmitted by the common ancestor AP, such as MAP TXS TFs, and the remaining TXOP is described in the CF-End2 frame. Since the destination common AP recognizes that the common ancestor AP is the TXOP holder, it can grasp the TXOP acquired by the common ancestor AP. Conventionally, the TXOP holder was only retained when the transmission was within the same BSS. However, it is assumed that an AP performing MAP operation can recognize and retain the TXOP holder for at least the physical packets within the same ESS even for transmissions in other BSSs. Alternatively, it may be possible that an AP performing MAP operation recognizes and retains only the APs within the same ESS as the TXOP holder.

[0243] When the common ancestor AP transmits a CE-End2 frame, since the common ancestor AP itself is naturally the TXOP holder, the remaining TXOP can be described in the CF-End2 frame.

[0244] When the STA receives a CF-End2 frame targeted at its own BSS and the basic NAV is set, it compares the value of the basic NAV with the remaining period of the TXOP described in the CF-End2 frame. If the end points are the same, that is, if the periods are the same, the basic NAV is reset.

[0245] <STA Operation Example 7c: Put the TXOP holder in the CF-End2 frame and reset the basic NAV only when it matches the holding information at the STA> The third operation example 7c of the solution is that the AP that transmits the CF-End2 frame describes the TXOP holder recognized by it in the CF-End2 frame, and the STA extracts and holds the TXOP holder of the frame that serves as the basis for setting its basic NAV when setting the basic NAV. That is, the STA holds the TA of the frame that serves as the basis for setting the NAV as the TXOP holder. When the frame is a CTS-to-self frame, the STA holds the RA as the TXOP holder. When the STA receives a CF-End2 frame targeted at its own BSS and determines that the MAC address held as the TXOP holder in the CF-End2 frame is the same as the TXOP holder of the set basic NAV, the STA resets the basic NAV. As described above, conventionally, the STA holds the TXOP holder only when the transmission is within its own BSS. However, if the STA that can transmit a response to the TF from its own AP under the MAP operation determines that the received packet is at least a physical packet within the same ESS even if it is from another BSS, it can recognize and hold the transmitting AP of the received packet as the TXOP holder. Alternatively, the STA may be configured to recognize and hold only the APs within the same ESS as the TXOP holder.

[0246] For example, the AP may set the BSS that is the target for resetting the basic NAV as described above in the RA field of the CF-End2 frame, set the address of the transmitting AP in the BSSID (TA) field of the CF-End2 frame, and then newly provide a field for inserting a new TXOP holder, the TXOP Holder field. The new field in this case is appropriately 6 octets, similar to other address fields.

[0247] Alternatively, the AP may put the address of the TXOP holder in the RA field of the CF-End2 frame instead of putting the BSSID of the BSS to be reset for the basic NAV. Considering that it is used under the MAP, the TXOP holder to be put here must be one of the APs, and since the MAC address of the AP is the BSSID, it can be said that the BSSID is put. Note that the first RA field may be changed to a TXOP Holder field. In STA operation example 7 of FIG. 28, AP2 transmitted by putting BSSID2, which is the BSSID of AP2, in the RA field of the CF-End2 frame, but in STA operation example 7c, AP2 transmits by putting BSSID1, which is the BSSID of AP1, in the RA field of the CF-End2 frame. For example, if the AP of the BSS to be reset for the basic NAV transmits a CF-End2 frame, the STA can determine whether it is the target for resetting the basic NAV using the BSSID(TA) field. When AP2 transmits a CF-End2 frame, BSSID2, which is the MAC address of AP2, is set in the BSSID(TA) of the CF-End2 frame, and only AP2 itself and the STAs connected to AP2 are the targets for resetting. When the TXOP holder of the basic NAV held by these APs / STAs matches the MAC address (here BSSID1(AP1)) described in the RA field of the CF-End2 frame, the basic NAV is reset.

[0248] When the basic NAV is extended, for example, the STA extracts the TXOP holder from the frame from which the NAV was extended and overwrites the held TXOP holder with the extracted TXOP holder.

[0249] When the STA limits the holding condition of the TXOP holder of the basic NAV, for example, when receiving a physical packet within the same ESS, or when receiving a physical packet from an AP within the same ESS, when receiving a physical packet that is not subject to TXOP holder holding and setting the basic NAV, the TXOP holder (specifically, the storage area for it) shall remain void. Even when the basic NAV is extended due to the reception of a physical packet that makes the TXOP holder void, the TXOP holder shall be made void even if it was held. When the STA receives a CF-End2 frame and the TXOP holder is not holding (i.e., in a void state), the STA does not reset the basic NAV.

[0250] Hereinafter, the configurations of the AP or STA will be described.

[0251] FIG. 29 is a functional block diagram of another example of the AP400. The AP400 includes a communication processing unit 401, a transmission unit 402, a reception unit 403, a plurality of, for example, four antennas 42A, 42B, 42C, 42D, a network processing unit 404, a wired interface (I / F) 405, and a memory 406. The AP400 is connected to a server 407 via the wired I / F 405. The communication processing unit 401 has the same functions as the MAC common processing unit 70 shown in FIG. 2. The transmission unit 402 has the same functions as the transmission processing unit 80 shown in FIG. 2. The reception unit 403 has the same functions as the reception processing unit 90 shown in FIG. 2. The network processing unit 404 has the same functions as the upper processing unit 10 shown in FIG. 2. Here, the communication processing unit 401 may internally hold a buffer for passing data to and from the network processing unit 404. This buffer may be a volatile memory such as DRAM or a non-volatile memory such as NAND or MRAM.

[0252] The network processing unit 404 controls data exchange with the communication processing unit 401, data writing and reading with the memory 406, and communication with the server 407 via the wired I / F 405. The network processing unit 404 may perform communication processing above the MAC layer and application layer processing, such as TCP / IP and UDP / IP. The operation of the network processing unit 404 may be performed by software (program) processing by a processor such as a CPU, by hardware, or by both software and hardware.

[0253] As an example, the communication processing unit 401 corresponds to a baseband integrated circuit, and the transmission unit 402 and the reception unit 403 correspond to RF integrated circuits that transmit and receive frames. The communication processing unit 401 and the network processing unit 404 may be configured by one integrated circuit (one chip). The part that processes the digital area and the part that processes the analog area of the transmission unit 402 and the reception unit 403 may be configured by different chips. Also, the communication processing unit 401 may execute communication processing above the MAC layer, such as TCP / IP and UDP / IP. Also, although the number of antennas 42A, 42B, 42C, 42D is four here, at least one antenna may be provided.

[0254] The memory 406 stores data received from the server 407 and data received by the reception unit 403. The memory 406 may be, for example, a volatile memory such as DRAM, or a non-volatile memory such as NAND or MRAM. Also, the memory 406 may be an SSD, HDD, SD card, eMMC, etc. The memory 406 may be external to the AP 400.

[0255] The wired I / F 405 transmits and receives data with the server 407. In FIG. 29, communication with the server 407 is performed wired, but communication with the server 407 may be performed wirelessly. In this case, a wireless I / F may be used instead of the wired I / F 405.

[0256] Server 407 is a communication device that receives a data transfer request for requesting data transmission and returns a response including the requested data. For example, an HTTP server (Web server), an FTP server, etc. are assumed. However, it is not limited thereto as long as it has a function of returning the requested data. It may also be a communication device operated by a user such as a PC or a smartphone. Further, it may communicate wirelessly with AP400.

[0257] When a STA belonging to the BSS of AP400 issues a data transfer request to server 407, a packet related to this data transfer request is transmitted to AP400. AP400 receives this packet via antennas 42A, 42B, 42C, and 42D, and the receiving unit 403 performs physical layer processing and the like, and the communication processing unit 401 performs MAC layer processing and the like.

[0258] The network processing unit 404 analyzes the packet received from the communication processing unit 401. Specifically, it checks the destination IP address, destination port number, etc. When the data of the packet is a data transfer request such as an HTTP GET request, the network processing unit 404 checks whether the data requested by this data transfer request (for example, the data existing at the URL requested by the HTTP GET request) is cached (stored) in the memory 406. A table associating a URL (or its reduced expression, for example, a hash value or an alternative identifier) with data is stored in the memory 406. Here, the fact that the data is cached in the memory 406 is expressed as there being cached data in the memory 406.

[0259] When there is no cached data in the memory 406, the network processing unit 404 sends a data transfer request to the server 407 via the wired I / F 405. That is, the network processing unit 404 sends a data transfer request to the server 407 on behalf of the STA. Specifically, the network processing unit 404 generates an HTTP request, performs protocol processing such as adding a TCP / IP header, and passes the packet to the wired I / F 405. The wired I / F 405 sends the received packet to the server 407.

[0260] The wired I / F 405 receives a packet that is a response to the data transfer request from the server 407. The network processing unit 404 determines from the IP header of the packet received via the wired I / F 405 that the packet is addressed to the STA, and passes the packet to the communication processing unit 401. The communication processing unit 401 performs MAC layer processing and the like on this packet, and the transmission unit 402 performs physical layer processing and the like, and sends the packet addressed to the STA from the antennas 42A, 42B, 42C, and 42D. Here, the network processing unit 404 associates the data received from the server 407 with a URL (or its abbreviated representation) and stores it as cached data in the memory 406.

[0261] When there is cached data in the memory 406, the network processing unit 404 reads out the data requested in the data transfer request from the memory 406 and transmits this data to the communication processing unit 401. Specifically, HTTP headers and the like are added to the data read out from the memory 406, protocol processing such as the addition of TCP / IP headers is performed, and packets are transmitted to the communication processing unit 401. At this time, as an example, the source IP address of the packet is set to the same IP address as the server 407, and the source port number is also set to the same port number as the server 407 (the destination port number of the packet transmitted by the STA that issued the data transfer request to the server 407). Therefore, from the perspective of the STA, it seems as if it is communicating with the server 407. The communication processing unit 401 executes processing at the MAC layer and the like for this packet, the transmission unit 402 executes processing at the physical layer and the like, and the packet destined for the STA is transmitted from the antennas 42A, 42B, 42C, 42D.

[0262] Through such an operation, frequently accessed data will be responded to based on the cached data stored in the memory 406, and the traffic between the server 407 and the AP 400 can be reduced. Note that the operation of the network processing unit 404 is not limited to the above-described operation. If it is a general cache proxy that acquires data from the server 407 instead of the STA, caches the data in the memory 406, and responds from the cached data in the memory 406 to a data transfer request for the same data, there is no problem with another operation.

[0263] The AP400 can be applied as the AP described with reference to FIGS. 1 to 28. The transmission of frames, data, or packets described with reference to FIGS. 1 to 28 may be executed using the cache data stored in the memory 406. Also, the information obtained from the frames, data, or packets received by the AP described with reference to FIGS. 1 to 28 may be cached in the memory 406. The frames transmitted by the AP described with reference to FIGS. 1 to 28 may include cached data or information based on the data. The information based on the data may be, for example, information on the presence or absence of data addressed to the STA, information on the size of the data, information on the size of the packets required for data transmission, or information such as the modulation method required for data transmission.

[0264] FIG. 29 describes an AP having a cache function. However, with the same block configuration as FIG. 29, an STA having a cache function can also be realized. The STA referred to here is a non-AP STA (as described above, an AP is also a form of wireless communication device). In this case, the wired I / F 405 may be omitted. The transmission of frames, data, or packets by the STA described with reference to FIGS. 1 to 28 may be executed using the cache data stored in the memory 406. Also, the information obtained from the frames, data, or packets received by the STA described with reference to FIGS. 1 to 28 may be cached in the memory 406. The frames transmitted by the STA described with reference to FIGS. 1 to 28 may include cached data or information based on the data. The information based on the data may be, for example, information on the presence or absence of data to be transmitted, information on the size of the data, information on the size of the packets required for data transmission, or information such as the modulation method required for data transmission.

[0265] FIG. 30 shows an overall configuration example of an example of an STA (non-AP STA) or an AP. This configuration example is an example, and the configuration example is not limited to this. The STA or AP has one or more antennas 1471 to 147 n (where n is an integer of 1 or more), a wireless LAN module (or a wireless communication device) 148, and a host system 149 are provided. The wireless LAN module 148 includes a host interface and is connected to the host system 149 through the host interface. The wireless LAN module 148 may be connected to the host system 149 through a connection cable or directly connected to the host system 149. Also, a configuration is possible in which the wireless LAN module 148 is mounted on a substrate by soldering or the like and is connected to the host system 149 through the wiring of the substrate. The host system 149 communicates with an external device using the wireless LAN module 148 and antennas 1471 to 147 n The communication protocol may include TCP / IP and a protocol of a layer higher than that. Alternatively, TCP / IP may be installed in the wireless LAN module 148, and the host system 149 may execute only the protocol of the higher layer. In this case, the configuration of the host system 149 can be simplified. The STA shown in FIG. 30 may be, for example, a mobile STA, a TV, a digital camera, a wearable device, a tablet, a smartphone, a game device, a network storage device, a monitor, a digital audio player, a web camera, a video camera, a projector, a navigation system, an external adapter, an internal adapter, a set-top box, a gateway, a printer server, a mobile access point, a router, an enterprise / service provider access point, a portable device, a handheld device, an automobile, or the like. The wireless LAN module 148 may have functions of other wireless communication standards such as LTE (Long Term Evolution) or LTE-Advanced (standards for mobile phones) in addition to IEEE802.11.

[0266] FIG. 31 shows an example of the hardware configuration of the wireless LAN module 148. This configuration is applicable when the wireless LAN module 148 is mounted on either a non-AP STA or an AP. In this example of the configuration, there is only one antenna, but two or more antennas may be provided. In this case, corresponding to each antenna, a set of a transmission system (216, 222 to 225), a reception system (217, 232 to 235), a PLL 242, a crystal oscillator (reference signal source) 243, and a switch 245 may be arranged in plural, and each set may be connected to the baseband circuit 212 respectively. The PLL 242 or the crystal oscillator 243 or both of them correspond to an oscillator.

[0267] The wireless LAN module includes a baseband IC (Integrated Circuit) 211, an RF (Radio Frequency) IC 221, a balun 225, a switch 245, and an antenna 247.

[0268] The baseband IC 211 includes a baseband circuit (control circuit) 212, a memory 213, a host interface 214, a CPU 215, a DAC (Digital to Analog Converter) 216, and an ADC (Analog to Digital Converter) 217.

[0269] The baseband IC 211 and the RF IC 221 may be formed on the same substrate. Also, the baseband IC 211 and the RF IC 221 may be configured as one chip. Both or either one of the DAC 216 and the ADC 217 may be arranged in the RF IC 221, or may be arranged in another IC. Also, both or either one of the memory 213 and the CPU 215 may be arranged in an IC different from the baseband IC.

[0270] Memory 213 stores data to be transferred to and from the host system. Memory 213 also stores information to be notified to the STA or AP, information notified from the STA or AP, or both. Further, memory 213 may store a program necessary for the execution of CPU 215 and be used as a working area when CPU 215 executes the program. Memory 213 may be a volatile memory such as SRAM or DRAM, or a non-volatile memory such as NAND or MRAM.

[0271] Host interface 214 is an interface for connecting to the host system. The interface may be anything such as UART, SPI, SDIO, USB, PCI Express, etc.

[0272] CPU 215 is a processor that controls baseband circuit 212 by executing a program. Baseband circuit 212 mainly performs MAC layer processing and physical layer processing. Baseband circuit 212, CPU 215, or both correspond to a communication control device that controls communication or a control unit that controls communication.

[0273] At least one of baseband circuit 212 and CPU 215 may include a clock generation unit that generates a clock, and manage the internal time by the clock generated by the clock generation unit.

[0274] Baseband circuit 212 performs, as physical layer processing, addition of a physical header, encoding, encryption, modulation processing, etc. to the frame to be transmitted, and generates, for example, two types of digital baseband signals (hereinafter, digital I signal and digital Q signal).

[0275] The DAC216 performs DA conversion on the signals input from the baseband circuit 212. More specifically, the DAC216 converts the digital I signal into an analog I signal and the digital Q signal into an analog Q signal. Note that there may be cases where transmission is carried out with a single system of signals without quadrature modulation. When multiple antennas are provided and the transmission signals of one or more systems are distributed and transmitted according to the number of antennas, the number of DACs etc. corresponding to the number of antennas may be provided.

[0276] The RFIC221 is, as an example, an RF analog IC or a high-frequency IC, or both of these. The RFIC221 includes a filter 222, a mixer 223, a preamplifier (PA) 224, a PLL (Phase Locked Loop) 242, a low-noise amplifier (LNA), a balun 235, a mixer 233, and a filter 232. Some of these elements may be arranged on the baseband IC211 or another IC. The filters 222 and 232 may be band-pass filters or low-pass filters.

[0277] The filter 222 extracts signals in a desired band from each of the analog I signal and the analog Q signal input from the DAC216. The PLL242 uses the oscillation signal input from the crystal oscillator 243, and generates a signal with a constant frequency synchronized with the phase of the input signal by dividing, multiplying, or both dividing and multiplying the oscillation signal. Note that the PLL242 includes a VCO (Voltage Controlled Oscillator), and based on the oscillation signal input from the crystal oscillator 243, performs feedback control using the VCO to obtain the signal with the constant frequency. The generated signal with the constant frequency is input to the mixer 223 and the mixer 233. The PLL242 corresponds to an example of an oscillator that generates a signal with a constant frequency.

[0278] The mixer 223 up-converts the analog I signal and the analog Q signal that have passed through the filter 222 to a radio frequency using a signal with a constant frequency supplied from the PLL 242. The preamplifier (PA) amplifies the radio-frequency analog I signal and analog Q signal generated by the mixer 223 to a desired output power. The balun 225 is a converter for converting a balanced signal (differential signal) into an unbalanced signal (single-ended signal). Although balanced signals are handled in the RFIC 221, unbalanced signals are handled from the output of the RFIC 221 to the antenna 247, so these signal conversions are performed by the balun 225.

[0279] The switch 245 is connected to the transmitting-side balun 225 during transmission and is connected to the receiving-side balun 235 or the RFIC 221 during reception. The control of the switch 245 may be performed by the baseband IC 211 or the RFIC 221, or there may be another circuit that controls the switch 245, and the switch 245 may be controlled from that circuit.

[0280] The radio-frequency analog I signal and analog Q signal amplified by the preamplifier 224 are subjected to a balanced-unbalanced conversion by the balun 225 and then radiated as radio waves into space from the antenna 247.

[0281] The antenna 247 may be a chip antenna, an antenna formed by wiring on a printed circuit board, or an antenna formed using a linear conductor element.

[0282] In the RFIC221, the LNA234 amplifies the signal received from the antenna 247 via the switch 245 to a demodulatable level while suppressing noise. The balun 235 converts the signal amplified by the low-noise amplifier (LNA) 234 from unbalanced to balanced. The mixer 233 down-converts the received signal converted to a balanced signal by the balun 235 to the baseband using a signal with a constant frequency input from the PLL242. More specifically, the mixer 233 has means for generating carrier waves that are 90° out of phase with each other based on the signal with a constant frequency input from the PLL242, and quadrature-demodulates the received signal converted by the balun 235 with the carrier waves that are 90° out of phase with each other to generate an I (In-phase) signal that is in phase with the received signal and a Q (Quad-phase) signal that is 90° behind in phase. The filter 232 extracts a signal of a desired frequency component from these I and Q signals. The I and Q signals extracted by the filter 232 are output from the RFIC221 after the gain is adjusted.

[0283] The ADC217 in the baseband IC211 performs AD conversion on the input signal from the RFIC221. More specifically, the ADC217 converts the I signal into a digital I signal and the Q signal into a digital Q signal. Note that it may be possible to receive only one system of signal without quadrature demodulation.

[0284] When a plurality of antennas are provided, the number of ADCs corresponding to the number of antennas may be provided. The baseband circuit 212 performs processing such as demodulation processing, error correction code processing, and physical header processing based on the digital I and Q signals to obtain a frame. The baseband circuit 212 performs MAC layer processing on the frame. Note that when the baseband circuit 212 implements TCP / IP, it is also possible to have a configuration that performs TCP / IP processing.

[0285] FIG. 32(a) and FIG. 32(b) are perspective views of two other examples of the wireless STA, respectively. The wireless STA in FIG. 32(a) is a notebook PC 301, and the wireless STA in FIG. 32(b) is a mobile terminal 321. The notebook PC 301 and the mobile terminal 321 are each equipped with wireless communication devices 305 and 315. As the wireless communication devices 305 and 315, the wireless communication devices mounted on the STA described so far, or the wireless communication devices mounted on the AP, or both of them can be used. The wireless STA equipped with the wireless communication device is not limited to a notebook PC or a mobile terminal. For example, a TV, a digital camera, a wearable device, a tablet, a smartphone, a game device, a network storage device, a monitor, a digital audio player, a web camera, a video camera, a projector, a navigation system, an external adapter, an internal adapter, a set-top box, a gateway, a printer server, a mobile access point, a router, an enterprise / service provider access point, a portable device, a handheld device, an automobile, etc. can also be equipped with the wireless STA.

[0286] In addition, the wireless communication device mounted on the wireless STA or the AP, or both of them can also be mounted on a memory card. An example of mounting the wireless communication device on a memory card is shown in FIG. 33. The memory card 331 includes a wireless communication device 355 and a memory card body 332. The memory card 331 uses the wireless communication device 335 for wireless communication with an external device (such as a wireless STA or an AP, or both of them). Note that in FIG. 33, the description of other elements (such as a memory, etc.) in the memory card 331 is omitted.

[0287] Another example of a wireless communication device (the wireless communication device of an AP or a wireless STA, or both) will be described. The other example may include a bus, a processor unit, and an external interface unit. The processor unit and the external interface unit are connected to an external memory (buffer) via the bus. Firmware operates in the processor unit. Thus, by including the firmware in the wireless communication device, it becomes possible to easily change the functions of the wireless communication device by rewriting the firmware. The processor unit in which the firmware operates may be a processing unit or a processor that performs the processing of the processing unit, or may be another processor that performs processing related to the function expansion or change of the processing. The processor unit in which the firmware operates may be provided in an AP, a wireless STA, or both. Alternatively, the processor unit may be provided in an integrated circuit in the wireless communication device mounted on the AP, or an integrated circuit in the wireless communication device mounted on the wireless STA.

[0288] In addition to the configuration of the wireless communication device (the wireless communication device of an AP or a wireless STA, or both) according to the above-described embodiment, a clock generation unit may be provided. The clock generation unit generates a clock and outputs the clock to the outside of the wireless communication device from an output terminal. Thus, by outputting the clock generated inside the wireless communication device to the outside and operating the host side with the clock output to the outside, it becomes possible to synchronize and operate the host side and the wireless communication device side.

[0289] In addition to the configuration of the wireless communication device (the wireless communication device of an AP or a wireless STA) according to the above-described embodiment, a power supply unit, a power supply control unit, and a wireless power feeding unit may be included. The power supply control unit is connected to the power supply unit and the wireless power feeding unit, and performs control to select the power supply to be supplied to the wireless communication device. Thus, by providing the power supply in the wireless communication device, it becomes possible to perform a low-power consumption operation with controlled power supply.

[0290] In addition to the configuration of the wireless communication device according to the above-described embodiment, a SIM card may be included. The SIM card is connected to, for example, a control unit in the wireless communication device. By providing the SIM card in the wireless communication device in this way, it becomes possible to easily perform authentication processing.

[0291] In addition to the configuration of the wireless communication device according to the above-described embodiment, a moving image compression / expansion unit may be included. The moving image compression / expansion unit is connected to a bus. By providing the moving image compression / expansion unit in the wireless communication device in this way, it becomes possible to easily perform transmission of compressed moving images and expansion of received compressed moving images.

[0292] In addition to the configuration of the wireless communication device (the wireless communication device of the AP or the wireless communication device of the wireless STA, or both of them) according to the above-described embodiment, an LED unit may be included. The LED unit is connected to a transmission unit or a reception unit or a control unit or a plurality of them. By providing the LED unit in the wireless communication device in this way, it becomes possible to easily notify the user of the operating state of the wireless communication device.

[0293] In addition to the configuration of the wireless communication device (the wireless communication device of the AP or the wireless communication device of the wireless STA, or both of them) according to the above-described embodiment, a vibrator unit may be included. The vibrator unit is connected to, for example, a control unit in the wireless communication device. By providing the vibrator unit in the wireless communication device in this way, it becomes possible to easily notify the user of the operating state of the wireless communication device.

[0294] In addition to the configuration of the wireless communication device (the wireless communication device of the AP or the wireless communication device of the wireless STA, or both of them) according to the above-described embodiment, a display may be included. The display may be connected to a control unit of the wireless communication device via a bus (not shown). By providing the display in this way and displaying the operating state of the wireless communication device on the display, it becomes possible to easily notify the user of the operating state of the wireless communication device.

[0295] Next, [1] frame types in a wireless communication system, [2] methods for disconnecting connections between wireless communication devices, [3] access methods of a wireless LAN system, and [4] frame intervals of a wireless LAN will be described.

[0296] [1] Frame Types in a Communication System Generally, frames handled on a wireless access protocol in a wireless communication system are roughly classified into three types: data frames, management frames, and control frames, as described above. These types are usually indicated by a header section commonly provided between frames. As a method for displaying frame types, it may be configured to distinguish the three types with one field, or it may be configured to distinguish them with a combination of two fields. In the IEEE802.11 standard, the identification of frame types is performed using two fields, Type and Subtype, in the FrameControl field in the frame header section of the MAC frame. The general classification of whether it is a data frame, a management frame, or a control frame is performed using the Type field, and the detailed classification within the generally classified frames, for example, the identification of a beacon frame within a management frame, is performed using the Subtype field.

[0297] A management frame is a frame used for managing a physical communication link with other wireless communication devices. For example, there are frames used for performing communication settings with other wireless communication devices, frames for releasing (i.e., disconnecting) a communication link, and frames related to power save operations in a wireless communication device.

[0298] A data frame is a frame that transmits data generated inside a wireless communication device to another wireless communication device after a physical communication link has been established with the other wireless communication device. The data is generated at the upper layer of this embodiment and is generated, for example, by a user's operation.

[0299] A control frame is a frame used for control when transmitting and receiving (exchanging) data frames with other wireless communication devices. A response frame transmitted for delivery confirmation when a wireless communication device receives a data frame or a management frame belongs to the control frame. The response frame is, for example, an ACK frame or a BlockACK frame. Also, an RTS frame and a CTS frame are control frames.

[0300] These three types of frames are sent as physical packets via the antenna after undergoing necessary processing at the physical layer as needed. In the IEEE 802.11 standard (including extended standards such as the aforementioned IEEE Std802.11ac-2013), there is an association process as one of the connection establishment procedures. The AssociationRequest frame and the AssociationResponse frame used in this process are management frames. Since the AssociationRequest frame and the AssociationResponse frame are unicast management frames, the receiving wireless communication device is required to transmit an ACK frame, which is a response frame. This ACK frame is a control frame as described above.

[0301] [2]Method for Disconnecting Connection between Wireless Communication Devices There are explicit and implicit methods for disconnecting a connection (release). As an explicit method, either one of the wireless communication devices establishing the connection transmits a frame for disconnection. In the IEEE802.11 standard, the Deauthentication frame corresponds to this and is classified as a management frame. Usually, the wireless communication device that transmits the frame for disconnecting the connection determines that the connection is disconnected at the time when the frame is transmitted, and the wireless communication device that receives the frame for disconnecting the connection determines that the connection is disconnected at the time when the frame is received. Thereafter, if it is a non-AP wireless communication device, it returns to the initial state in the communication phase, for example, the state of searching for a BSS to connect to. When disconnecting the connection between a wireless communication AP and a certain wireless communication device, for example, if the wireless communication AP has a connection management table for managing the wireless communication devices associated with its own BSS, the information related to the wireless communication device is deleted from the connection management table. For example, when an AID is assigned at the stage where the wireless communication AP permits the connection to each wireless communication device associated with its own BSS in the association process, the holding information associated with the AID of the wireless communication device whose connection has been disconnected may be deleted, and the AID may be released and assigned to other newly associated wireless communication devices.

[0302] On the other hand, as an implicit method, when no frame transmission (transmission of data frames and management frames, or transmission of response frames to the frames transmitted by the device itself) is detected from the wireless communication device of the connection partner that has established the connection for a certain period of time, a determination of disconnection of the connection state is made. The reason for having such a method is that in the situation of determining the disconnection of the connection as described above, a physical wireless link cannot be ensured, such as when the communication distance from the connected wireless communication device is separated and the wireless signal cannot be received or decoded. That is, it is because the reception of the frame for disconnecting the connection cannot be expected.

[0303] As a specific example of determining the disconnection of the connection in an implicit manner, a timer is used. For example, when transmitting a data frame that requests a delivery confirmation response frame, a first timer (for example, a retransmission timer for the data frame) that limits the retransmission period of the frame is started, and retransmission is performed if a delivery confirmation response frame for the frame is not received until the first timer expires (that is, until the desired retransmission period has elapsed). When a delivery confirmation response frame for the frame is received, the first timer can be stopped.

[0304] On the other hand, when the first timer expires without receiving a delivery confirmation response frame, for example, a management frame is transmitted to check whether the wireless communication device of the connection partner still exists (i.e., whether a wireless link can be secured), and at the same time, a second timer (for example, a retransmission timer for the management frame) that limits the retransmission period of the frame is started. Similar to the first timer, with the second timer as well, retransmission is performed if a delivery confirmation response frame for the frame is not received until the second timer expires, and when the second timer expires, it is determined that the connection has been disconnected. At the stage where it is determined that the connection has been disconnected, a frame for disconnecting the connection may be transmitted.

[0305] Alternatively, when a frame is received from a wireless communication device of a connection partner, a third timer is started. Each time a frame is newly received from the wireless communication device of the connection partner, the third timer is stopped and restarted from the initial value. When the third timer expires, a management frame is transmitted to check whether the wireless communication device of the connection partner still exists (i.e., whether a wireless link can be established) in the same manner as described above. At the same time, a second timer (e.g., a retransmission timer for the management frame) that restricts the retransmission period of the frame is started. Also in this case, if a delivery confirmation response frame for the frame is not received until the second timer expires, retransmission is performed. When the second timer expires, it is determined that the connection has been disconnected. Also in this case, at the stage where it is determined that the connection has been disconnected, a frame for disconnecting the connection may be transmitted. The management frame for checking whether the wireless communication device of the connection partner still exists in the latter case may be different from the management frame in the former case. Also, although the same second timer as in the former case is used here as the timer for restricting the retransmission of the management frame in the latter case, a different timer may be used.

[0306] [3] Access method of wireless LAN system For example, there is a wireless LAN system that assumes communication or competition with multiple wireless communication devices. In the IEEE802.11 wireless LAN, CSMA / CA (Carrier Sense Multiple Access with Carrier Avoidance) is used as the basic access method. In the method of detecting the transmission of a certain wireless communication device and performing transmission after a fixed time from the end of its transmission, multiple wireless communication devices that have detected the transmission of that wireless communication device will transmit simultaneously. As a result, the wireless signals will collide and the frame transmission will fail. By detecting the transmission of a certain wireless communication device and waiting for a random time from the end of its transmission, the transmissions of multiple wireless communication devices that have detected the transmission of that wireless communication device will be probabilistically dispersed. Therefore, if there is only one wireless communication device that subtracts the earliest time within the random time, the frame transmission of the wireless communication device will succeed, and frame collisions can be prevented. Since the acquisition of the transmission right based on the random value becomes fair among multiple wireless communication devices, the method adopting Carrier Avoidance can be said to be a suitable method for sharing the wireless medium among multiple wireless communication devices.

[0307] [4] Frame interval of wireless LAN The frame interval of the IEEE802.11 wireless LAN will be described. The frame intervals used in the IEEE802.11 wireless LAN include distributed coordination function interframe space (DIFS), arbitration interframe space (AIFS), point coordination function interframe space (PIFS), short interframe space (SIFS), extended interframe space (EIFS), reduced interframe space (RIFS), etc.

[0308] The definition of the inter-frame interval is defined in the IEEE802.11 wireless LAN as the continuous period that should be opened after confirming carrier sense idle before transmission, and the exact period from the previous frame is not discussed. Therefore, in the description of the IEEE802.11 wireless LAN system here, this definition is followed. In the IEEE802.11 wireless LAN, the waiting time during random access based on CSMA / CA is the sum of a fixed time and a random time. To clarify the fixed time, it can be said that such a definition exists.

[0309] DIFS and AIFS are inter-frame intervals used when attempting to start frame exchange during a contention period that competes with other wireless communication devices based on CSMA / CA. DIFS is used when there is no distinction in priority based on traffic type, and AIFS is used when priority is provided based on the traffic identifier (TID).

[0310] Since the operations related to DIFS and AIFS are similar, the following mainly uses AIFS for explanation. In the IEEE802.11 wireless LAN, access control including starting frame exchange is performed at the MAC layer. Furthermore, when QoS (Quality of Service) is supported when data is passed from the upper layer, the traffic type is notified together with the data, and the data is classified into priority classes at the time of access based on the traffic type. This class at the time of access is called the access category (AC). Therefore, the value of AIFS is provided for each access category.

[0311] PIFS is an inter-frame interval that enables access with higher priority than other competing wireless communication devices, and its period is shorter than either the value of DIFS or AIFS. SIFS is an inter-frame interval that can be used when transmitting a response control frame or when continuing frame exchange in bursts after once obtaining the transmission right. EIFS is an inter-frame interval that is activated when frame reception fails (it is determined that the received frame has an error).

[0312] RIFS is an inter-frame interval that can be used when a burst of multiple frames is continuously transmitted to the same wireless communication device after once acquiring the transmission right. While using RIFS, a response frame from the wireless communication device of the transmission partner is not requested.

[0313] Here, an example of frame exchange during a contention period based on random access in the IEEE802.11 wireless LAN is shown in Fig. 34.

[0314] Assume that when a transmission request for a data frame (W_DATA1) occurs in a certain wireless communication device, the medium is recognized as busy (busymedium) as a result of carrier sense. In this case, after leaving AIFS for a fixed time from the point when the carrier sense becomes idle, and then when a random time (random backoff) has elapsed, the data frame W_DATA1 is transmitted to the communication partner. Note that when the medium is recognized as not busy, that is, when the medium is idle as a result of carrier sense, after leaving AIFS for a fixed time from the point when carrier sense is started, the data frame W_DATA1 is transmitted to the communication partner.

[0315] The random time is obtained by multiplying a pseudo-random integer derived from a uniform distribution between 0 and an integer contention window (CW) by a slot time. Here, multiplying CW by the slot time is called the CW time width. The initial value of CW is given by CWmin, and each time retransmission occurs, the value of CW is increased until it reaches CWmax. Both CWmin and CWmax have values for each access category, similar to AIFS. In the wireless communication device that is the destination of W_DATA1, when the reception of a data frame is successful and the data frame is a frame that requires the transmission of a response frame, a response frame (W_ACK1) is transmitted SIFS time after the end of the occupancy of the physical packet containing the data frame on the wireless medium. The wireless communication device that transmitted W_DATA1 can transmit the next frame (e.g., W_DATA2) SIFS time after the end of the occupancy of the physical packet containing W_ACK1 on the wireless medium, provided that it is within the transmission burst time limit when it receives W_ACK1.

[0316] AIFS, DIFS, PIFS, and EIFS are functions of SIFS and the slot time, where SIFS and the slot time are defined for each physical layer. Also, parameters such as AIFS, CWmin, and CWmax, which have values for each access category, can be set for each communication group (Basic Service Set (BSS) in IEEE802.11 wireless LAN), but default values are defined.

[0317] For example, in the standard formulation of 802.11ac, assuming that the SIFS is 16 μs and the slot time is 9 μs, the PIFS is thereby 25 μs, the DIFS is 34 μs, and for AIFS, the inter-frame interval for the access category BACKGROUND (AC_BK) has a default value of 79 μs, the inter-frame interval for BESTEFFORT (AC_BE) has a default value of 43 μs, and the inter-frame intervals for VIDEO (AC_VI) and VOICE (AC_VO) have default values of 34 μs. The default values of CWmin and CWmax are 31 and 1023 for AC_BK and AC_BE respectively, 15 and 31 for AC_VI, and 7 and 15 for AC_VO. Note that the EIFS is basically the sum of the SIFS, the DIFS, and the time length of the response frame when transmitting at the slowest mandatory physical rate. In a wireless communication device capable of an efficient EIFS approach, it is also possible to estimate the occupancy time length of the physical packet carrying the response frame to the physical packet for which the EIFS has been activated, and set it as the sum of the SIFS, the DIFS, and that estimated time.

[0318] Note that the frames described in each embodiment may refer to those called packets in the IEEE802.11 standard or a compliant standard, such as a NullDataPacket.

[0319] Also, frames transmitted by multiple STAs may be frames with different contents or frames with the same content. As a general expression, when expressing that multiple STAs transmit or receive the Xth frame, the contents of these Xth frames may be the same or different. X is an arbitrary value.

[0320] The terms used in this embodiment should be interpreted broadly. For example, the term "processor" may include general-purpose processors, central processing units (CPUs), microprocessors, digital signal processors (DSPs), controllers, microcontrollers, state machines, etc. Depending on the situation, "processor" may refer to application-specific integrated circuits, field-programmable gate arrays (FPGAs), programmable logic circuits (PLDs), etc. "Processor" may refer to a combination of processing devices such as multiple microprocessors, a combination of a DSP and a microprocessor, or one or more microprocessors cooperating with a DSP core.

[0321] As another example, the term "memory" may include any electronic component capable of storing electronic information. "Memory" may refer to random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable PROM (EEPROM), non-volatile random access memory (NVRAM), flash memory, magnetic or optical data storage, which are readable by a processor. If a processor reads, writes, or both reads and writes information to and from a memory, the memory can be said to communicate electrically with the processor. The memory may be integrated with the processor, and in this case too, the memory can be said to be communicating electrically with the processor. Also, the circuit may be a plurality of circuits arranged on a single chip, or one or more circuits distributed and arranged on a plurality of chips or a plurality of devices.

[0322] Note that the present invention is not limited to the above embodiments as they are, and at the implementation stage, the components can be modified and embodied without departing from the gist. Also, various inventions can be formed by appropriately combining a plurality of components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in the embodiments. Further, components from different embodiments may be appropriately combined.

Description of Reference Numerals

[0323] AP... base station, STA... terminal, 10... upper processing unit, 20... MAC processing unit, 30... PHY processing unit, 40... MAC / PHY management unit, 50... analog processing unit, 60... antenna, 70... MAC common processing unit, 80... transmission processing unit, 90... reception processing unit.< / map>

Claims

1. A wireless communication device housed in a first wireless communication group together with a first terminal, wherein the first wireless communication group forms an extended wireless communication group together with a second wireless communication group that houses a second wireless communication device and a second terminal, the wireless communication device receives a first frame for allocating to the wireless communication device a partial period of a first available time of a communication medium acquired by the second wireless communication device, when using a partial period of the first available time, transmits a second transmission frame including a first field containing information representing the partial period to the first terminal, the first terminal generates, based on the information contained in the first field, information indicating that the communication medium is virtually busy during the partial period. A wireless communication device.

2. The wireless communication device according to claim 1, wherein when using a part of the first available time, the wireless communication device transmits a physical packet including a physical header including a second field containing information representing the partial period to the first terminal.

3. The wireless communication device according to claim 2, wherein the first terminal generates, based on the information contained in the second field, information indicating that the communication medium is virtually busy during the partial period.

4. The wireless communication device acquires the right to transmit a packet, acquires a second available time of the communication medium, and transmits a third frame for allocating a partial period of the second available time to the second wireless communication device to the second wireless communication device. The wireless communication device according to claim 1.

5. The wireless communication device according to claim 4, wherein the third frame includes a third field containing information representing a partial period of the second available time and a fourth field containing identification information of the second wireless communication device.

6. The wireless communication device divides a partial period of the second available time to the first terminal using the third frame, the fourth field contains identification information of the second wireless communication device or identification information of the first terminal, the identification information of the first terminal has values in a first range, and the identification information of the second wireless communication device has values in a second range different from the first range. The wireless communication device according to claim 5.

7. The wireless communication device is a wireless communication device compliant with the IEEE 802.11ax standard. The wireless communication device according to any one of claims 1 to 6, wherein the first field is a Duration / ID field. **Claim 8**: The wireless communication device is a wireless communication device compliant with the IEEE 802.11ax standard, The wireless communication device according to claim 2 or claim 3, wherein the second field is a TXOP field. **Claim 9**: The wireless communication device is a wireless communication device compliant with the IEEE 802.11ax standard, The wireless communication device according to claim 5 or claim 6, wherein the fourth field is an AID12 field.

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