Transmission opportunity sharing in wireless LAN system

Abstract

The present disclosure relates to transmission opportunity (TXOP) sharing in a wireless LAN system. According to an embodiment of the present disclosure, a method performed by a first access point (AP) configured to operate in a wireless LAN system comprises the steps of: receiving, from a second AP, information about a cooperation group related to the second AP; determining whether a third AP belonging to a cooperation group related to the first AP belongs to the cooperation group related to the second AP, on the basis of the information about the cooperation group related to the second AP; transmitting a cooperation announcement frame to the second AP and the third AP, on the basis that the third AP does not belong to the cooperation group related to the second AP; and after transmitting the cooperation announcement frame to the second AP and the third AP, transmitting, to the second AP and the third AP, a transmission opportunity (TXOP) sharing frame comprising information about a first allocation period allocated to the second AP within a TXOP period and information about a second allocation period allocated to the third AP within the TXOP period, wherein at least a portion of the first allocation period overlaps the second allocation period.

Description

Sharing transmission opportunities in wireless LAN systems

[0001] The present disclosure relates to transmission opportunity (TXOP) sharing in a wireless LAN system.

[0002] Next-generation Wi-Fi (e.g., IEEE 802.11be and / or later) aims to support ultra-high reliability in signal transmission to STAs, and various technologies are being considered to support high throughput, low latency, and extended range.

[0003] For example, in wireless LAN systems, multiple terminals share the same medium. Therefore, various medium access control (MAC) techniques are employed to prevent collisions and ensure fair access. One such approach is a Transmission Opportunity (TXOP)-based approach, which allows a specific STA (Station) to transmit data continuously for a set period of time.

[0004] In particular, recent research is focused on technologies that enable simultaneous or cooperative transmission among multiple access points (APs) by sharing the TXOP segment acquired by one AP with other APs. For example, if an AP grants a TXOP to a specific AP, that AP can distribute transmission opportunities to other APs via a TXOP sharing indication, or multiple APs can be configured to sequentially transmit data within the same TXOP.

[0005] This TXOP sharing technology offers the advantages of improving media utilization efficiency, reducing transmission delay, and mitigating performance degradation in high-density network environments. Accordingly, next-generation wireless LAN standards such as IEEE 802.11ax include multi-STA support techniques based on TXOP sharing or scheduling.

[0006] The present disclosure provides a method and device for TXOP sharing in a wireless LAN system.

[0007] According to an embodiment of the present disclosure, a method performed by a first access point (AP) configured to operate in a wireless LAN system includes the steps of: receiving, from a second AP, information about a cooperation group associated with the second AP; determining, based on the information about the cooperation group associated with the second AP, whether a third AP belonging to the cooperation group associated with the first AP belongs to a cooperation group associated with the second AP; transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to the cooperation group associated with the second AP; and transmitting, after transmitting the cooperation announcement frame to the second AP and the third AP, a TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP period and information about a second allocation period assigned to the third AP within the TXOP period, wherein at least a portion of the first allocation period overlaps the second allocation period.

[0008] According to an embodiment of the present disclosure, a method performed by a second access point (AP) configured to operate in a wireless LAN system includes the steps of: transmitting information about a cooperation group associated with the second AP to a first AP; receiving a cooperation announcement frame from the first AP based on a third AP belonging to the cooperation group associated with the first AP not belonging to the cooperation group associated with the second AP; receiving, after receiving the cooperation announcement frame from the first AP, a transmission opportunity (TXOP) shared frame from the first AP, the TXOP shared frame including information about a first allocation period assigned to the second AP and information about a second allocation period assigned to the third AP within the TXOP period; and performing a frame exchange with one or more STAs (stations) associated with the second AP during the first allocation period, wherein at least a portion of the first allocation period overlaps the second allocation period.

[0009] In various embodiments, devices for implementing the above-described methods are provided.

[0010] The present disclosure may have various advantageous effects.

[0011] For example, medium utilization in multi-AP operations (e.g., C-TDMA operations) can be improved by simultaneously allocating time to two or more DAPs. Furthermore, by simultaneously allocating time to two or more DAPs, the SAP can prevent neighboring STAs from occupying the medium until the TXOP is released (i.e., the successful release of the TXOP can be guaranteed).

[0012] The beneficial effects that can be achieved through specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, various technical effects may be understood and / or derived from the present disclosure by those skilled in the art. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure.

[0013] FIG. 1 illustrates an example of a transmitting device and / or a receiving device of the present disclosure.

[0014] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0015] Figure 3 is a diagram illustrating a general link setup process.

[0016] Figure 4 illustrates an embodiment of multi-link (ML).

[0017] FIG. 5 illustrates a modified example of a transmitting device and / or a receiving device of the present disclosure.

[0018] FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of the present disclosure.

[0019] Figure 7 shows the operation according to UL-MU.

[0020] Figure 8 shows an example of a header of a MAC frame.

[0021] Figure 9 illustrates a trigger frame format. The trigger frame format may also be referred to as the structure of a trigger frame.

[0022] Figure 10 shows an example of the user information field format of MU-RTS TXS TF.

[0023] Figure 11 shows an example of multi-AP operation based on Co-TDMA between APs.

[0024] FIG. 12 illustrates an example of a multi-AP negotiation procedure according to an embodiment of the present disclosure.

[0025] FIG. 13 illustrates an example of a multi-AP selection procedure according to an embodiment of the present disclosure.

[0026] Figure 14 shows an example of the topology of APs.

[0027] FIG. 15 illustrates an example of a method performed by a first AP for TXOP sharing according to an embodiment of the present disclosure.

[0028] FIG. 16 illustrates an example of a method performed by a second AP for TXOP sharing according to an embodiment of the present disclosure.

[0029] FIG. 17 illustrates an example of a simultaneous TXS procedure according to an embodiment of the present disclosure.

[0030] In this disclosure, “A or B” can mean “only A,” “only B,” or “both A and B.” In other words, “A or B” in this disclosure can be interpreted as “A and / or B.” For example, “A, B or C” in this disclosure can mean “only A,” “only B,” “only C,” or “any combination of A, B, and C.”

[0031] As used herein, a slash ( / ) or a comma can mean "and / or." For example, "A / B" can mean "A and / or B." Accordingly, "A / B" can mean "only A," "only B," or "both A and B." For example, "A, B, C" can mean "A, B, or C."

[0032] In the present disclosure, “at least one of A and B” may mean “only A,” “only B,” or “both A and B.” Additionally, in the present disclosure, the expressions “at least one of A or B” or “at least one of A and / or B” may be interpreted identically to “at least one of A and B.”

[0033] In addition, parentheses used in the present disclosure may mean “for example.” Specifically, when “control information (UHR-Signal field)” is indicated, the “UHR-Signal field” may be suggested as an example of “control information.” In other words, the “control information” of the present disclosure is not limited to the “UHR-Signal field,” and the “UHR-Signal field” may be suggested as an example of “control information.” In addition, even when indicated as “control information (UHR-Signal field),” the “UHR-Signal field” may be suggested as an example of “control information.”

[0034] Additionally, as used herein, “a / an” can mean “at least one” or “one or more.” Additionally, terms ending in “(s)” can mean “at least one” or “one or more.”

[0035] Additionally, the expressions “based on” or “on the basis of” or “according to” used in this disclosure mean “based at least in part on” and do not mean “based solely on.”

[0036] Technical features individually described in one drawing in this disclosure may be implemented individually or simultaneously.

[0037] The following examples of the present disclosure can be applied to various wireless communication systems. For example, the following examples of the present disclosure can be applied to a wireless local area network (WLAN) system. For example, the present disclosure can be applied to the IEEE 802.11a / g / n / ac / ax / be / bn standards. Furthermore, the examples of the present disclosure can be applied to the Ultra High Reliability (UHR) standard or a next-generation wireless LAN standard that enhances IEEE 802.11bn. Furthermore, the examples of the present disclosure can be applied to a mobile communication system. For example, the examples of the present disclosure can be applied to a mobile communication system based on the Long Term Evolution (LTE) standard and its evolution based on the 3rd Generation Partnership Project (3GPP) standard.

[0038] In order to explain the technical features of the present disclosure, technical features to which the present disclosure can be applied are described below.

[0039] FIG. 1 illustrates an example of a transmitting device and / or a receiving device of the present disclosure.

[0040] An example of FIG. 1 can perform various technical features described below. FIG. 1 relates to at least one STA (station). For example, the STA (110, 120) of the present disclosure may also be referred to by various names such as a mobile terminal, a wireless device, a Wireless Transmit / Receive Unit (WTRU), a User Equipment (UE), a Mobile Station (MS), a Mobile Subscriber Unit, or simply a user. The STA (110, 120) of the present disclosure may also be referred to by various names such as a network, a base station, a Node-B, an access point (AP), a repeater, a router, a relay, etc. The STA (110, 120) of the present disclosure may also be referred to by various names such as a receiving apparatus, a transmitting apparatus, a receiving STA, a transmitting STA, a receiving device, a transmitting device, etc.

[0041] For example, STA (110, 120) may perform the role of an AP (access point) or a non-AP role. That is, STA (110, 120) of the present disclosure may perform the functions of an AP and / or a non-AP. In the present disclosure, an AP may also be indicated as an AP STA.

[0042] The STA (110, 120) of the present disclosure can support various communication standards other than the IEEE 802.11 standard. For example, it can support communication standards according to the 3GPP standard (e.g., LTE, LTE-A, 5G NR standard). In addition, the STA of the present disclosure can be implemented in various devices such as a mobile phone, a vehicle, a personal computer, etc. In addition, the STA of the present disclosure can support communication for various communication services such as voice calls, video calls, data communications, and autonomous driving (Self-Driving, Autonomous-Driving).

[0043] In the present disclosure, STA (110, 120) may include a medium access control (MAC) and a physical layer interface for a wireless medium that follow the provisions of the IEEE 802.11 standard.

[0044] Based on the sub-drawing (a) of Fig. 1, STA (110, 120) is described as follows.

[0045] The first STA (110) may include a processor (111), a memory (112), and a transceiver (113). The illustrated processor, memory, and transceiver may each be implemented as separate chips, or at least two blocks / functions may be implemented through a single chip.

[0046] The transceiver (113) of the first STA performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0047] For example, the first STA (110) can perform the intended operation of the AP. For example, the processor (111) of the AP can receive a signal through the transceiver (113), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (112) of the AP can store a signal received through the transceiver (113) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0048] For example, the second STA (120) can perform the intended operation of a non-AP STA. For example, the transceiver (123) of the non-AP performs signal transmission and reception operations. Specifically, it can transmit and receive IEEE 802.11 packets (e.g., IEEE 802.11a / b / g / n / ac / ax / be, etc.).

[0049] For example, the processor (121) of the Non-AP STA can receive a signal through the transceiver (123), process the received signal, generate a transmission signal, and perform control for signal transmission. The memory (122) of the Non-AP STA can store a signal received through the transceiver (123) (i.e., a reception signal) and store a signal to be transmitted through the transceiver (i.e., a transmission signal).

[0050] For example, in the specification below, the operation of a device indicated as AP may be performed in the first STA (110) or the second STA (120). For example, if the first STA (110) is an AP, the operation of the device indicated as AP may be controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (110). In addition, control information related to the operation of the AP or a transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110). In addition, when the second STA (110) is an AP, the operation of the device indicated as an AP is controlled by the processor (121) of the second STA (120), and a related signal can be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the AP or the transmission / reception signal of the AP can be stored in the memory (122) of the second STA (110).

[0051] For example, in the specification below, the operation of a device indicated as a non-AP (or User-STA) may be performed in the STA (110) or the second STA (120). For example, if the second STA (120) is a non-AP, the operation of the device indicated as a non-AP may be controlled by the processor (121) of the second STA (120), and a related signal may be transmitted or received through a transceiver (123) controlled by the processor (121) of the second STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (122) of the second STA (120). For example, if the first STA (110) is a non-AP, the operation of a device indicated as a non-AP is controlled by the processor (111) of the first STA (110), and a related signal may be transmitted or received through a transceiver (113) controlled by the processor (111) of the first STA (120). In addition, control information related to the operation of the non-AP or the transmission / reception signal of the AP may be stored in the memory (112) of the first STA (110).

[0052] In the following specification, devices called (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. may refer to the STA (110, 120) of FIG. 1. For example, devices indicated as (transmitting / receiving) STA, first STA, second STA, STA1, STA2, AP, first AP, second AP, AP1, AP2, (transmitting / receiving) Terminal, (transmitting / receiving) device, (transmitting / receiving) apparatus, network, etc. without specific drawing symbols may also refer to the STA (110, 120) of FIG. 1. For example, in the example below, the operation of various STAs transmitting and receiving signals (e.g., PPPDU) may be performed by the transceiver (113, 123) of FIG. 1. In addition, in the example below, the operation of various STAs generating transmission and reception signals or performing data processing or calculations in advance for transmission and reception signals may be performed by the processor (111, 121) of FIG. 1.For example, an example of an operation for generating a transmission / reception signal or performing data processing or operation in advance for a transmission / reception signal may include 1) an operation for determining / obtaining / configuring / computing / decoding / encoding bit information of a subfield (SIG, STF, LTF, Data) field included in a PPDU, 2) an operation for determining / configuring / obtaining time resources or frequency resources (e.g., subcarrier resources) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 3) an operation for determining / configuring / obtaining a specific sequence (e.g., a pilot sequence, an STF / LTF sequence, an extra sequence applied to SIG) used for a subfield (SIG, STF, LTF, Data) field included in a PPDU, 4) a power control operation and / or a power saving operation applied to an STA, 5) an operation related to determining / obtaining / configuring / computing / decoding / encoding an ACK signal, etc. Additionally, in the examples below, various information (e.g., information related to fields / subfields / control fields / parameters / power, etc.) used by various STAs for determining / acquiring / configuring / computing / decoding / encoding transmission / reception signals can be stored in the memory (112, 122) of FIG. 1.

[0053] The device / STA of the sub-drawing (a) of FIG. 1 described above can be modified as in the sub-drawing (b) of FIG. 1. Hereinafter, the STA (110, 120) of the present disclosure will be described based on the sub-drawing (b) of FIG. 1.

[0054] For example, the transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the transceiver illustrated in sub-drawing (a) of FIG. 1 described above. For example, the processing chip (114, 124) illustrated in sub-drawing (b) of FIG. 1 may include a processor (111, 121) and a memory (112, 122). The processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (b) of FIG. 1 may perform the same function as the processor (111, 121) and the memory (112, 122) illustrated in sub-drawing (a) of FIG. 1 described above.

[0055] The mobile terminal, wireless device, Wireless Transmit / Receive Unit (WTRU), User Equipment (UE), Mobile Station (MS), Mobile Subscriber Unit, user, user STA, network, Base Station, Node-B, Access Point (AP), repeater, router, relay, receiving device, transmitting device, receiving STA, transmitting STA, receiving Device, transmitting Device, receiving Apparatus, and / or transmitting Apparatus described below may refer to the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may refer to the processing chip (114, 124) illustrated in the sub-drawing (b) of FIG. 1. That is, the technical feature of the present disclosure may be performed in the STA (110, 120) illustrated in the sub-drawings (a) / (b) of FIG. 1, or may be performed only in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1. For example, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal generated in the processor (111, 121) illustrated in the sub-drawings (a) / (b) of FIG. 1 is transmitted through the transceiver (113, 123) illustrated in the sub-drawings (a) / (b) of FIG. 1. Alternatively, the technical feature that the transmitting STA transmits a control signal may be understood as a technical feature that the control signal to be transmitted to the transceiver (113, 123) is generated in the processing chip (114, 124) illustrated in the sub-drawings (b) of FIG. 1.

[0056] For example, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal being received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (a) of FIG. 1 being acquired by a processor (111, 121) illustrated in sub-drawing (a) of FIG. 1. Alternatively, the technical feature of a receiving STA receiving a control signal can be understood as a technical feature of a control signal received by a transceiver (113, 123) illustrated in sub-drawing (b) of FIG. 1 being acquired by a processing chip (114, 124) illustrated in sub-drawing (b) of FIG.

[0057] Referring to the sub-drawing (b) of FIG. 1, software code (115, 125) may be included in the memory (112, 122). The software code (115, 125) may include instructions that control the operation of the processor (111, 121). The software code (115, 125) may be included in various programming languages.

[0058] The processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, and / or a data processing device. The processor may be an application processor (AP). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may include at least one of a digital signal processor (DSP), a central processing unit (CPU), a graphics processing unit (GPU), and a modem (modulator and demodulator). For example, the processor (111, 121) or processing chip (114, 124) illustrated in FIG. 1 may be a SNAPDRAGON® series processor manufactured by Qualcomm®, an EXYNOS® series processor manufactured by Samsung®, an A series processor manufactured by Apple®, a HELIO® series processor manufactured by MediaTek®, an ATOM® series processor manufactured by INTEL®, or an enhanced processor thereof.

[0059] In the present disclosure, uplink may mean a link for communication from a non-AP STA to an AP STA, and uplink PPDU / packet / signal, etc. may be transmitted through the uplink. In addition, in the present disclosure, downlink may mean a link for communication from an AP STA to a non-AP STA, and downlink PPDU / packet / signal, etc. may be transmitted through the downlink.

[0060] Figure 2 is a conceptual diagram showing the structure of a wireless local area network (WLAN).

[0061] The upper part of Figure 2 shows the structure of the infrastructure BSS (basic service set) of IEEE (institute of electrical and electronic engineers) 802.11.

[0062] Referring to the top of FIG. 2, the wireless LAN system may include one or more infrastructure BSSs (200, 205) (hereinafter, BSS). The BSSs (200, 205) are a collection of APs and STAs, such as an access point (AP) 225 and a station (STA1, 200-1), that have successfully synchronized and can communicate with each other, and are not a concept that designates a specific area. The BSS (205) may also include one or more STAs (205-1, 205-2) that can be associated with one AP (230).

[0063] A BSS may include at least one STA, an AP (225, 230) providing a distribution service, and a distribution system (DS, 210) connecting multiple APs.

[0064] A distributed system (210) can connect multiple BSSs (200, 205) to implement an extended service set (ESS, 240). An ESS (240) can be used as a term to indicate a network formed by connecting one or more APs through the distributed system (210). APs included in a single ESS (240) can have the same SSID (service set identification).

[0065] The portal (portal, 220) can act as a bridge to connect a wireless LAN network (IEEE 802.11) to another network (e.g., 802.X).

[0066] In a BSS such as the upper part of Fig. 2, a network between APs (225, 230) and a network between APs (225, 230) and STAs (200-1, 205-1, 205-2) can be implemented. However, it may also be possible to establish a network and perform communication between STAs without an AP (225, 230). A network that establishes a network and performs communication between STAs without an AP (225, 230) is defined as an ad-hoc network or an independent basic service set (IBSS).

[0067] The bottom of Figure 2 is a conceptual diagram showing IBSS.

[0068] Referring to the bottom of Fig. 2, the IBSS is a BSS that operates in ad-hoc mode. Since the IBSS does not include an AP, there is no centralized management entity. That is, in the IBSS, the STAs (250-1, 250-2, 250-3, 255-4, 255-5) are managed in a distributed manner. In the IBSS, all STAs (250-1, 250-2, 250-3, 255-4, 255-5) can be mobile STAs, and access to the distributed system is not permitted, forming a self-contained network.

[0069] Figure 3 is a diagram illustrating a general link setup process.

[0070] In step S310, the STA may perform a network discovery operation. This network discovery operation may include scanning by the STA. That is, for the STA to access the network, it must find a network it can join. Before joining a wireless network, the STA must identify compatible networks. The process of identifying networks in a specific area is called scanning. Scanning methods include active scanning and passive scanning.

[0071] Figure 3 illustrates a network discovery operation that includes an active scanning process as an example. In active scanning, an STA performing scanning transmits a probe request frame to discover which APs exist in the vicinity while moving between channels and waits for a response. A responder transmits a probe response frame to the STA that transmitted the probe request frame in response to the probe request frame. Here, the responder may be the STA that last transmitted a beacon frame in the BSS of the channel being scanned. In a BSS, the AP transmits the beacon frame, so the AP becomes the responder. In an IBSS, the STAs within the IBSS take turns transmitting beacon frames, so the responder is not constant. For example, an STA that transmits a probe request frame on channel 1 and receives a probe response frame on channel 1 can store BSS-related information included in the received probe response frame and move to the next channel (e.g., channel 2) to perform scanning (i.e., transmitting and receiving probe requests / responses on channel 2) in the same manner.

[0072] Although not shown in the example of FIG. 3, the scanning operation can also be performed in a passive scanning manner. An STA performing scanning based on passive scanning can wait for a beacon frame while moving between channels. A beacon frame is one of the management frames in IEEE 802.11. It announces the presence of a wireless network and is periodically transmitted so that the scanning STA can find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame, and in the IBSS, the STAs within the IBSS take turns transmitting the beacon frame. When the scanning STA receives a beacon frame, it stores the information about the BSS included in the beacon frame and moves to another channel, recording the beacon frame information on each channel. An STA that receives a beacon frame can store the BSS-related information included in the received beacon frame, move to the next channel, and perform scanning on the next channel in the same manner.

[0073] An STA that discovers a network can perform an authentication process through step S320. This authentication process may be referred to as the first authentication process to clearly distinguish it from the security setup operation of step S340 described below. The authentication process of S320 may include a process in which the STA transmits an authentication request frame to the AP, and the AP responds by transmitting an authentication response frame to the STA. The authentication frame used for the authentication request / response corresponds to a management frame.

[0074] The authentication frame may include information such as an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a Robust Security Network (RSN), and a Finite Cyclic Group.

[0075] An STA can transmit an authentication request frame to an AP. The AP can determine whether to grant authentication to the STA based on the information contained in the received authentication request frame. The AP can provide the result of the authentication process to the STA via an authentication response frame.

[0076] A successfully authenticated STA may perform an association process based on step S330. The association process includes a process in which the STA transmits an association request frame to the AP, and the AP transmits an association response frame to the STA in response. For example, the association request frame may include information related to various capabilities, such as a beacon listen interval, a service set identifier (SSID), supported rates, supported channels, RSN, mobility domain, supported operating classes, a Traffic Indication Map Broadcast request, and interworking service capabilities. For example, the association response frame may contain information related to various capabilities, status codes, Association ID (AID), supported rates, Enhanced Distributed Channel Access (EDCA) parameter sets, Received Channel Power Indicator (RCPI), Received Signal to Noise Indicator (RSNI), mobility domains, timeout interval (association comeback time), overlapping BSS scan parameters, TIM broadcast response, QoS maps, etc.

[0077] In step S340, the STA may perform a security setup process. The security setup process of step S340 may include, for example, a process of setting up a private key through a four-way handshaking using an Extensible Authentication Protocol over LAN (EAPOL) frame.

[0078] Figure 4 illustrates an example of a multi-link (ML).

[0079] As illustrated in FIG. 4, multiple multi-link devices (MLDs) can communicate over a remote link. The MLDs can be categorized into AP MLDs including multiple AP STAs and non-AP MLDs including multiple non-AP STAs. That is, the AP MLD can include affiliated APs (i.e., AP STAs), and the non-AP MLD can include affiliated STAs (i.e., non-AP STAs, or user-STAs).

[0080] A multilink may include a first link and a second link, and different channels / subchannels / frequency resources may be allocated to the first and second links. The first and second multilinks may be identified through a link ID of 4 bits (or other n bits). The first and second links may be configured in the same 2.4 GHz, 5 GHz, or 6 GHz band. Alternatively, the first link and the second link may be configured in different bands.

[0081] The AP MLD of FIG. 4 includes three affiliated APs. In the example of FIG. 4, AP1 may operate in the 2.4 GHz band, AP2 may operate in the 5 GHz band, and AP3 may operate in the 6 GHz band. In the example of FIG. 4, the first link in which AP1 and non-AP1 operate may be defined as a channel / subchannel / frequency resource within the 2.4 GHz band. Furthermore, in the example of FIG. 4, the second link in which AP2 and non-AP2 operate may be defined as a channel / subchannel / frequency resource within the 5 GHz band. Furthermore, in the example of FIG. 4, the third link in which AP3 and non-AP3 operate may be defined as a channel / subchannel / frequency resource within the 6 GHz band.

[0082] In the example of FIG. 4, AP1 may initiate a multi-link setup procedure (ML setup procedure) by transmitting an Association Request frame to non-AP STA1. In the example of FIG. 4, non-AP STA1 may transmit an Association Response frame in response to the Association Request frame. Each AP (e.g., AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the AP illustrated in FIG. 1 and / or FIG. 2, and each non-AP (e.g., non-AP1 / 2 / 3) illustrated in FIG. 4 may be identical to the STA (i.e., user-STA or non-AP STA) illustrated in FIG. 1 and / or FIG. 2.

[0083] The specific features of the present disclosure are not limited to the specific features of FIG. 4. That is, the number of links can be defined in various ways, and multiple links can be defined in various ways within at least one band.

[0084] FIG. 5 illustrates a modified example of a transmitting device and / or a receiving device of the present disclosure.

[0085] The devices (e.g., AP STA, non-AP STA) illustrated in FIGS. 1 to 4 may be modified as illustrated in FIG. 5. The transceiver (530) of FIG. 5 may be identical to the transceivers (113, 123) of FIG. 1. The transceiver (530) of FIG. 5 may include a receiver and a transmitter.

[0086] The processor (510) of FIG. 5 may be identical to the processor (111, 121) of FIG. 1. Alternatively, the processor (510) of FIG. 5 may be identical to the processing chip (114, 124) of FIG. 1.

[0087] The memory (150) of FIG. 5 may be the same as the memory (112, 122) of FIG. 1. Alternatively, the memory (150) of FIG. 5 may be a separate external memory different from the memory (112, 122) of FIG. 1.

[0088] Referring to FIG. 5, a power management module (511) manages power to a processor (510) and / or a transceiver (530). A battery (512) supplies power to the power management module (511). A display (513) outputs results processed by the processor (510). A keypad (514) receives input to be used by the processor (510). The keypad (514) may be displayed on the display (513). A SIM card (515) may be an integrated circuit used to securely store an international mobile subscriber identity (IMSI) and an associated key used to identify and authenticate a subscriber in a mobile phone device, such as a mobile phone or computer.

[0089] Referring to FIG. 5, the speaker (540) can output sound-related results processed by the processor (510). The microphone (541) can receive sound-related input to be used by the processor (510).

[0090] FIG. 6 illustrates an example of a PPDU (physical protocol data unit or physical layer (PHY) protocol data unit) transmitted / received by an STA of the present disclosure.

[0091] The STA (e.g., AP STA, non-AP STA, AP MLD, non-AP MLD) of the present disclosure can transmit and / or receive the PPDU of FIG. 6. The PPDU described in the present disclosure may have, for example, the structure of FIG. 6. In addition, the PPDU described in the present disclosure may be called by various names such as a transmission PPDU, a reception PPDU, a first type PPDU, or an Nth type PPDU, etc. The PPDU described in the present disclosure can be used in a WLAN system defined according to IEEE 802.11bn and / or a next-generation WLAN system that improves upon IEEE 802.11bn.

[0092] The PPDU of FIG. 6 may be related to various PPDU types used in a UHR system. For example, the example of FIG. 6 may be used for at least one of a single-user (SU) mode / type / transmission, a multi-user (MU) mode / type / transmission, and a null data packet (NDP) mode / type / transmission related to channel sounding. For example, if the example of FIG. 6 is related to NDP, the Data field illustrated may be omitted. If the PPDU of FIG. 6 is used for a trigger-based (TB) mode, the UHR-SIG of FIG. 6 may be omitted. In other words, an STA that has received a trigger frame for UL-MU (Uplink-MU) communication may transmit a PPDU with the UHR-SIG omitted in the example of FIG. 6.

[0093] In FIG. 6, L-STF or UHR-LTF may be called a preamble or physical preamble, and may be generated / transmitted / received / acquired / decoded in the physical layer (included in the transmitting / receiving STA).

[0094] Each block illustrated in Fig. 6 may be called a field / subfield / signal, etc. The names of these fields / subfields / signals may be, as illustrated in Fig. 6, L-STF (legacy short training field), L-LTF (legacy long training field), L-SIG (legacy signal), RL-SIG (repeated L-SIG), U-SIG (Universal Signal), UHR-SIG (UHR-signal), etc.

[0095] The subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields in FIG. 6 may be set to 312.5 kHz, and the subcarrier spacing of the UHR-STF, UHR-LTF, and Data fields may be set to 78.125 kHz. That is, the tone index (or subcarrier index) of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and UHR-SIG fields may be expressed in units of 312.5 kHz, and the tone index (or subcarrier index) of the UHR-STF, UHR-LTF, and Data fields may be expressed in units of 78.125 kHz.

[0096] In the PPDU of Fig. 6, L-LTF and L-STF may be identical to conventional fields (e.g., non-HT LTF and non-HT STF defined in conventional WLAN standards).

[0097] The L-SIG field of FIG. 6 may include, for example, 24 bits of bit information. For example, the 24 bits of information may include a 4 bit Rate field, a 1 bit Reserved bit, a 12 bit Length field, a 1 bit Parity bit, and a 6 bit Tail bit. For example, the 12 bit Length field may include information about the length or time duration of the PPDU. For example, the value of the 12 bit Length field may be determined based on the type of the PPDU. For example, if the PPDU is a non-HT (non-High Throughput), HT (High Throughput), VHT (Very High Throughput) PPDU, or an EHT (extremely high throughput) PPDU or UHR PPDU, the value of the Length field may be determined as a multiple of 3. For example, if the PPDU is a HE PPDU, the value of the Length field may be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, for non-HT, HT, VHT PPDU, EHT PPDU, UHR PPDU, the value of the Length field can be determined as a multiple of 3, and for HE (High-Efficiency) PPDU, the value of the Length field can be determined as "a multiple of 3 + 1" or "a multiple of 3 + 2". In other words, the Length field in an UHR PPDU is set to a value satisfying the condition that the remainder is zero when LENGTH is divided by 3.

[0098] For example, (non-AP and AP) STAs can apply BCC encoding based on a code rate of 1 / 2 to the 24 bits of information in the L-SIG field. Then, the transmitting STA can obtain 48 BCC coded bits. BPSK modulation can be applied to the 48 coded bits to generate 48 BPSK symbols. The transmitting STA can map the 48 BPSK symbols to positions excluding the pilot subcarriers {subcarrier index -21, -7, +7, +21} and the DC subcarrier {subcarrier index 0}. As a result, the 48 BPSK symbols can be mapped to subcarrier indices -26 to -22, -20 to -8, -6 to -1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA can additionally map the signal {-1, -1, -1, 1} to the subcarrier indices {-28, -27, +27, +28}. The above signal can be used for channel estimation for the frequency domain corresponding to {-28, -27, +27, +28}.

[0099] For example, (non-AP and AP) STA can generate RL-SIG, which is generated in the same manner as L-SIG. BPSK modulation can be applied to RL-SIG. Receiving (non-AP and AP) STA can determine whether the received PPDU is a HE PPDU, EHT PPDU, or UHR PPDU based on the presence of RL-SIG. In other words, if RL-SIG is present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of HE PPDU, EHT PPDU, or UHR PPDU. In other words, if RL-SIG is not present, receiving (non-AP and AP) STA can determine whether the received PPDU is one of non-HT PPDU, HT PPDU, or VHT PPDU. In other words, the RL-SIG field is a repeat of the L-SIG field and is used to differentiate an UHR PPDU from a non-HT PPDU, HT PPDU, and VHT PPDU.

[0100] After the RL-SIG in Fig. 6, a U-SIG (Universal SIG) may be inserted. The U-SIG may be called by various names such as the first SIG field, the first SIG, the first type SIG, the control signal, the control signal field, the first (type) control signal, the common control field, and the common control signal.

[0101] A U-SIG can contain N bits of information and can include information for identifying the type of EHT PPDU. For example, a U-SIG can be formed based on two symbols (e.g., two consecutive OFDM symbols). Each symbol (e.g., an OFDM symbol) for a U-SIG can have a duration of 4 microseconds. Each symbol of a U-SIG can be used to transmit 26 bits of information. For example, each symbol of a U-SIG can be transmitted and received based on 52 data tones and 4 pilot tones.

[0102] For example, A bit information (e.g., 52 uncoded bits) can be transmitted through U-SIG, and the first symbol of U-SIG can transmit the first X bits of information (e.g., 26 uncoded bits) out of the total A bit information, and the second symbol of U-SIG can transmit the remaining Y bits of information (e.g., 26 uncoded bits) out of the total A bit information. For example, the transmitting STA can obtain 26 uncoded bits included in each U-SIG symbol. The transmitting STA can perform convolutional encoding (i.e., BCC encoding) based on a rate of R=1 / 2 to generate 52 coded bits, and perform interleaving on the 52 coded bits. The transmitting STA can perform BPSK modulation on the interleaved 52 coded bits to generate 52 BPSK symbols allocated to each U-SIG symbol. A single U-SIG symbol can be transmitted based on 56 tones (subcarriers) from subcarrier index -28 to subcarrier index +28, excluding DC index 0. The 52 BPSK symbols generated by the transmitting STA can be transmitted based on the remaining tones (subcarriers) excluding the pilot tones -21, -7, +7, and +21.

[0103] For example, A bit information (e.g., 52 uncoded bits) transmitted by U-SIG may include a CRC field (e.g., a 4-bit long field) and a tail field (e.g., a 6-bit long field). The CRC field and the tail field may be transmitted through the second symbol of the U-SIG. The CRC field may be generated based on 26 bits allocated to the first symbol of the U-SIG and the remaining 16 bits excluding the CRC / tail field within the second symbol, and may be generated based on a conventional CRC calculation algorithm. In addition, the tail field may be used to terminate the trellis of the convolutional decoder and may be set to, for example, "000000".

[0104] The A bit information (e.g., 52 uncoded bits) transmitted by the U-SIG (or U-SIG field) can be divided into version-independent bits and version-dependent bits. For example, the size of the version-independent bits can be fixed or variable. For example, the version-independent bits can be assigned only to the first symbol of the U-SIG, or the version-independent bits can be assigned to both the first symbol and the second symbol of the U-SIG. For example, the version-independent bits and the version-dependent bits can be called by various names, such as the first control bit and the second control bit.

[0105] For example, the version-independent bits of the U-SIG may include a 3-bit PHY version identifier. For example, the 3-bit PHY version identifier may include information related to the PHY version of the transmitted and received PPDU. For example, a first value (e.g., a value of 000) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an EHT PPDU. In addition, a second value (e.g., a value of 001) of the 3-bit PHY version identifier may indicate that the transmitted and received PPDU is an UHR PPDU.

[0106] In other words, when the (AP / non-AP) STA transmits an EHT PPDU, it can set the 3-bit PHY version identifier to the first value. In other words, the receiving (AP / non-AP) STA can determine that the received PPDU is an EHT PPDU based on the PHY version identifier having the first value, and can determine that the received PPDU is an UHR PPDU based on the PHY version identifier having the second value.

[0107] For example, the version-independent bits of U-SIG may include a 1-bit UL / DL flag field. The first value of the 1-bit UL / DL flag field relates to UL communication, and the second value of the UL / DL flag field relates to DL communication.

[0108] For example, the version-independent bits of U-SIG may include information about the length of a transmission opportunity (TXOP) and information about the BSS color ID.

[0109] For example, if a UHR PPDU is classified into various types (e.g., a type related to SU transmission (performed based on UL or DL), a type related to DL transmission, a type related to NDP transmission, a type related to DL non-MU-MIMO, a type related to DL MU-MIMO, a type related to Multi-AP operation, a type related to CO-BF (Coordinated beamforming), SR (Spatial Reuse), a type related to C-OFDMA (Coordinated OFDMA), a type related to CO-TDMA (Coordinated TDMA)), information about the type of the EHT PPDU (e.g., 2-bit or 3-bit information) can be included in the version-dependent bits of the U-SIG.

[0110] For example, a U-SIG may include information about 1) a bandwidth field including information about a bandwidth, 2) a field including information about a Modulation and Coding Scheme (MCS) technique applied to the UHR-SIG, 3) an indication field including information about whether a dual subcarrier modulation (DCM) technique is applied to the UHR-SIG, 4) a field including information about the number of symbols used for the UHR-SIG, 5) a field including information about whether the UHR-SIG is generated over the entire band, 6) a field including information about the type of UHR-LTF / STF, and 7) a field indicating the length of the UHR-LTF and the CP length.

[0111] Preamble puncturing may be applied to the PPDU of FIG. 6. Preamble puncturing refers to applying puncturing to a portion of the entire bandwidth of the PPDU (e.g., the secondary 20 MHz band). For example, when an 80 MHz PPDU is transmitted, the STA may apply puncturing to the secondary 20 MHz band within the 80 MHz band, and transmit the PPDU only through the primary 20 MHz band and the secondary 40 MHz band.

[0112] For example, the pattern of preamble puncturing can be preset. For example, when the first puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band within the 80 MHz band. For example, when the second puncturing pattern is applied, puncturing can be applied only to one of the two secondary 20 MHz bands included in the secondary 40 MHz band within the 80 MHz band. For example, when the third puncturing pattern is applied, puncturing can be applied only to the secondary 20 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band). For example, when the fourth puncturing pattern is applied, a primary 40 MHz band included in the primary 80 MHz band within the 160 MHz band (or 80+80 MHz band) may be present, and puncturing may be applied to at least one 20 MHz channel that does not belong to the primary 40 MHz band.

[0113] Information regarding preamble puncturing applied to the PPDU may be included in the U-SIG and / or UHR-SIG. For example, the first field of the U-SIG may include information regarding the contiguous bandwidth of the PPDU, and the second field of the U-SIG may include information regarding preamble puncturing applied to the PPDU.

[0114] For example, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following method. If the bandwidth of the PPDU exceeds 80 MHz, the U-SIG may be individually configured in units of 80 MHz. For example, if the bandwidth of the PPDU is 160 MHz, the PPDU may include a first U-SIG for the first 80 MHz band and a second U-SIG for the second 80 MHz band. In this case, the first field of the first U-SIG may include information regarding the 160 MHz bandwidth, and the second field of the first U-SIG may include information regarding preamble puncturing applied to the first 80 MHz band (i.e., information regarding the preamble puncturing pattern). Additionally, the first field of the second U-SIG may include information about a 160 MHz bandwidth, and the second field of the second U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern). Meanwhile, the UHR-SIG consecutive to the first U-SIG may include information about preamble puncturing applied to the second 80 MHz band (i.e., information about a preamble puncturing pattern), and the UHR-SIG consecutive to the second U-SIG may include information about preamble puncturing applied to the first 80 MHz band (i.e., information about a preamble puncturing pattern).

[0115] Additionally or alternatively, U-SIG and UHR-SIG may include information regarding preamble puncturing based on the following methods. U-SIG may include information regarding preamble puncturing for all bands (i.e., information regarding preamble puncturing patterns). That is, UHR-SIG may not include information regarding preamble puncturing, and only U-SIG may include information regarding preamble puncturing (i.e., information regarding preamble puncturing patterns).

[0116] U-SIGs can be configured in 20 MHz units. For example, if an 80 MHz PPDU is configured, U-SIGs can be duplicated. That is, four identical U-SIGs can be included within an 80 MHz PPDU. PPDUs exceeding the 80 MHz bandwidth can contain different U-SIGs.

[0117] The UHR-SIG of FIG. 6 may include control information for a receiving STA. The UHR-SIG may be transmitted via at least one symbol, and each symbol may have a length of 4 us. Information regarding the number of symbols used for the UHR-SIG may be included in the U-SIG.

[0118] UHR-SIG provides additional signals to the U-SIG field to enable STAs to interpret / decode UHR PPDUs. The UHR-SIG field may contain U-SIG overflow bits that are common to all users. The UHR-SIG field also contains resource allocation information, allowing STAs to look up resources used in fields containing data fields / UHR-STF / UHR-LTF (i.e., UHR modulated fields of an UHR PPDU).

[0119] The frequency resources of the UHR-LTF, UHR-STF, and data fields illustrated in FIG. 6 can be determined based on RUs (resource units) defined by multiple subcarriers / tones. That is, the UHR-LTF, UHR-STF, and data fields of the present disclosure can be transmitted / received through RUs (resource units) defined by multiple subcarriers / tones.

[0120] Figure 7 illustrates an operation according to UL-MU. As illustrated, a transmitting STA (e.g., AP) can acquire a TXOP (725) by performing channel access through contending (i.e., backoff operation) and transmit a trigger frame (730). That is, the transmitting STA (e.g., AP) can transmit a PPDU including a trigger frame (730). When a PPDU including a trigger frame is received, a TB (trigger-based) PPDU is transmitted after a delay of SIFS.

[0121] TB PPDUs (741, 742) are transmitted at the same time and can be transmitted from multiple STAs (e.g., User STAs) whose AIDs are indicated in the Trigger frame (730). The ACK frame (750) for the TB PPDU can be implemented in various forms. For example, the ACK frame (750) for the TB PPDU can be implemented in the form of a BA (block ACK).

[0122] In FIG. 7, transmission(s) of a Trigger Frame (730), a TB PPDU (741, 742) and / or an ACK frame (750) may be performed within a TXOP (725).

[0123] Below, we explain NAV (Network Allocation Vector).

[0124] When a Source (e.g., AP STA / non-AP STA) that wants to transmit data transmits an RTS (request to send) frame to a Destination (e.g., AP STA / non-AP STA) that receives the data, the Destination can notify surrounding terminals that it will receive the data by transmitting a CTS (clear to send) frame. In other words, the Destination designated as the receiver through the RTS frame can transmit a CTS frame. If the Source that transmitted the RTS frame receives the CTS frame, the Source can start transmitting data to the Destination.

[0125] Meanwhile, if an STA other than the Destination designated as the receiver through the RTS frame receives the RTS frame, or if an STA other than the Source that transmitted the RTS frame receives the CTS frame, the STA may set a network allocation vector (NAV). An STA that has set a NAV may not transmit data during the NAV period, thereby avoiding collisions between the STA and the Source / Destination. On the other hand, if the Destination designated as the receiver through the RTS frame receives the RTS frame, or if the Source that transmitted the RTS frame receives the CTS frame, the Source / Destination does not set a NAV.

[0126] If a CTS frame (e.g., PHY-RXSTART.indication primitive) is not received within a certain period from the time when the RTS frame is received (e.g., the time when the MAC receives the PHY-RXEND.indication primitive corresponding to the RTS frame), STAs that have set or updated the NAV through the RTS frame may reset the NAV (e.g., 0). The certain period may be (2*aSIFSTime + CTS_Time + aRxPHYStartDelay + 2*aSlotTime). The CTS_Time may be calculated based on the length of the CTS frame and the data rate indicated by the RTS frame.

[0127] In addition to the RTS frame and / or CTS frame, NAV setting / resetting / updating may also be performed based on fields of other various frames, such as non-HT PPDU, HT PPDU, VHT PPDU or HE PPDU (e.g., duration field in MAC header of MAC frame). For example, if the RA field in the received MAC frame / RTS frame / CTS frame does not match its own address (e.g., MAC address), the STA may set / reset / update NAV based on the value of the duration field in the received MAC frame / RTS frame / CTS frame.

[0128] Non-AP STAs must maintain two NAVs, and APs can maintain two NAVs: an intra-BSS NAV and a basic NAV. The intra-BSS NAV can be updated / set by PPDUs within the BSS. The basic NAV can be updated / set by inter-BSS PPDUs, or PPDUs that cannot be classified as inter-BSS or intra-BSS.

[0129] Below, the structure and types / subtypes of MAC frames are described.

[0130] Figure 8 shows an example of a header of a MAC frame.

[0131] As illustrated, the MAC frame may include a frame control field / information of 2 octets in length, a duration field / information of 2 octets in length, a RA (Receiver Address) field / information of 6 octets in length, and a TA (Transmitter Address) field / information of 6 octets in length. As illustrated in FIG. 8, the four fields may be consecutive to each other. The MAC header of FIG. 8 may be modified in various ways, and a new field may be inserted between the four illustrated fields, or at least one of the illustrated fields may be omitted.

[0132] The MAC header illustrated in Fig. 8 may be positioned at the very front of the MAC frame. That is, the MAC frame may include a MAC header as illustrated in Fig. 8 and MAC body fields / information subsequent to the MAC header. The MAC frame including the MAC header of Fig. 8 is inserted / included in the data field of the PPDU (e.g., UHR PPDU) illustrated in Fig. 5.

[0133] The MAC frames included in the data field of the PPDU of this specification can be classified into various types. For example, the MAC frames of this specification can be classified into control frames, management frames, and data frames.

[0134] For example, the management frame includes Association Request, Association Response, Reassociation Request, Reassociation Response, Probe Request, Probe Response, Beacon, Disassociation, Authentication, and Deauthentication frames / signals defined in conventional WLAN. For the management frame, the values ​​of the type fields (B3 and B2) in FIG. 8 are set to 00. In addition, the values ​​of the subtype fields (B7, B6, B5, B4) in FIG. 8 are as follows: Association Request (0000), Association Response (0001), Reassociation Request (0010), Reassociation Response (0011), Probe Request (0100), Probe Response (0101), Beacon (1000), Disassociation (1010), Authentication (1011), Deauthentication (1100).

[0135] For example, the control frame includes Trigger Beamforming Report Poll, NDP Announcement (NDPA), Control Frame Extension, Control Wrapper, Block Ack Request (BlockAckReq), Block Ack (BlockAck), PS-Poll, RTS, CTS, Ack, and CF-End frames / signals defined in conventional WLAN. For the control frame, the values ​​of the type fields (B3 and B2) in FIG. 8 are set to 01. Also, the values ​​of the subtype fields (B7, B6, B5, B4) of FIG. 8 are as follows: Trigger (0010), Beamforming Report Poll (0100), NDP Announcement (0101), Control Frame Extension (0110), Control Wrapper (0111), BlockAckReq (1000), BlockAck (1001), PS-Poll (1010), RTS (1011), CTS (1100), Ack (1101), CF-End (1110).

[0136] For example, the data frame includes (QoS) Data, (QoS) Null, etc. defined in conventional WLAN. For the management frame, the value of the type field (B3 and B2) of Fig. 8 is set to 10.

[0137] The MAC frame / signal used in this specification can be identified through the type field / information and subtype field / information described above. For example, the “trigger frame” in this specification can mean a MAC frame in which the type bits B3 and B2 bits in the frame control field of the MAC header are set to 01, and the subtype bits B7, B6, B5, B4 bits in the frame control field are also set to 0010. Various MAC frames described in this specification are inserted / included in the data field of various PPDUs (e.g., HE / VHT / HE / EHT / UHR PPDU).

[0138] Figure 9 illustrates a trigger frame format. The trigger frame format may also be referred to as the structure of a trigger frame.

[0139] Referring to FIG. 9, a trigger frame may include a frame control field, a duration / ID field, a receiver address (RA) field, a transmitter address (TA) field, a common info field, a user info list field, a padding field, and / or a frame check sequence (FCS) field. Optionally, the trigger frame may further include a special user info field between the common info field and the user info list field. The user info list field may include one or more user info fields. The frame control field, the duration / ID field, the RA field, and the TA field may constitute a MAC header.

[0140] For example, the common information field may include a trigger type subfield. The trigger type subfield value may indicate a trigger frame variant, as shown in Table 1:

[0141] Trigger type subfield valueTrigger frame variant0Basic1Beamforming Report Poll (BFRP)2MU-BAR3MU-RTS4Buffer Status Report Poll (BSRP)5GCR MU-BAR6Bandwidth Query Report Poll (BQRP)7NDP Feedback Report Poll (NFRP)8Ranging9-15Reserved

[0142] For example, if the value of the trigger type subfield is set to 0, the trigger frame may be a basic trigger frame. For example, if the value of the trigger type subfield is set to 3, the trigger frame may be a MU (multi-user) RTS trigger frame. Meanwhile, according to the EHT (or 802.11be) standard, in order to support peer-to-peer (P2P) transmission to a non-AP STA, an AP may allocate a portion of the time interval within the TXOP acquired by the AP. In order to allocate a portion of the time interval within the TXOP, a TXOP Sharing Mode subfield may be defined within the Common Info Field of the MU-RTS trigger frame. When the value of the TXOP Sharing Mode subfield is non-zero, such an MU-RTS trigger frame may be referred to as an MU-RTS TXOP Sharing (TXS) trigger frame (TF). The values ​​of the TXOP Sharing Mode subfield are described in Table 2 below:

[0143] Triggered TXOP Sharing Mode subfield valueDescription0MU-RTS that does not initiate MU-RTS TXOP sharing procedure.1MU-RTS that initiates MU-RTS TXOP sharing procedure wherein a scheduledSTA can only transmit MPDU(s) addressed to its associated AP.2MU-RTS that initiates MU-RTS TXOP sharing procedure wherein a scheduled STA can transmit MPDU(s) addressed to its associated AP or addressed to another STA.3Reserved.

[0144] For example, if the value of the TXOP shared mode subfield is 1, one or more (non-TB) PPDU transmissions to the AP may be supported. If the value of the TXOP shared mode subfield is 2, not only (non-TB) PPDU transmissions to the AP but also P2P transmissions may be supported. In the present disclosure, the MU-RTS TXS TF may also be briefly referred to as a TXS trigger frame.

[0145] Figure 10 shows an example of the user information field format of MU-RTS TXS TF.

[0146] Referring to FIG. 10, the user information field may include an AID subfield, an RU allocation subfield, an allocation duration subfield, reserved bits, and / or a PS160 subfield.

[0147] The AID subfield may indicate the AID for the corresponding STA. The RU allocation subfield may indicate RU allocation for the corresponding STA.

[0148] The allocation period subfield can contain 9 bits from B20 to B28 in the MU-RTS TXS TF and can indicate the allocation period in 16us units. In this case, the maximum length of the allocation period that can be indicated by the allocation period subfield can be 2^9= 8192us.

[0149] The PS160 subfield may indicate the primary 160MHz channel or the second 160MHz channel to which RU or MRU allocation applies.

[0150] Meanwhile, to enable terminals to maintain continuous WLAN connectivity over a wider area, numerous APs are being installed adjacent to each other. However, overlapping BSSs of multiple APs can lead to issues such as radio interference and transmission collisions between APs. To address these issues, various technologies related to coordination between APs in the frequency, time, and spatial domains (e.g., RU selection, joint transmission, nulling) have been proposed. Furthermore, various issues that may arise during inter-AP cooperation need to be addressed.

[0151] In this disclosure, multi-AP operation is proposed. Multi-AP operation may be based on a technique for reducing various interferences, such as inter-symbol interference (ISI), through coordination with neighboring APs (e.g., APs located in overlapping BSSs).

[0152] For example, multi-AP operation can be categorized into multi-AP cooperation schemes (or, cooperative schemes) based on various technologies / types / formats / protocols. For example, the cooperative scheme may include Coordinated TDMA (Co-TDMA), which distinguishes wireless resources allocated to multiple APs based on the time domain. Additionally or alternatively, the cooperative scheme may include Coordinated OFDMA (C-OFDMA), which distinguishes wireless resources allocated to multiple APs based on the frequency domain. Additionally or alternatively, the cooperative scheme may include Coordinated Spatial Reuse (Co-SR), which applies spatial reuse (SR) to at least one AP. Additionally or alternatively, the cooperative scheme may include Coordinated beamforming (Co-BF) / nulling, which transmits by nulling interference generated from neighboring APs (e.g., adjacent APs / STAs, and / or OBSS APs / OBSS STAs). Additionally or alternatively, the cooperative scheme may include AP selection, in which an AP with a good channel condition among neighboring APs (e.g., at least one AP located within a BSS or OBSS and with a good channel condition) transmits. Additionally or alternatively, the cooperative scheme may include Joint Transmission (JTX) or Joint Transmission (JT), in which multiple APs (e.g., multiple APs within the same BSS / OBSS, or multiple APs within different BSS / OBSS) cooperate to perform simultaneous transmission and reception, and JTX / JT may be implemented based on Joint Beamforming or Joint MU-MIMO.

[0153] In this disclosure, “multi-AP (cooperative) operation” may also be referred to as “multi-AP (cooperative) transmission.” Furthermore, “multi-AP (cooperative) operation / transmission” and “multi-AP cooperative scheme (or cooperative scheme)” may be used interchangeably.

[0154] When the triggered TXOP sharing protocol is utilized for multi-AP cooperation (e.g., Co-TDMA), transmissions within the BSS of each cooperative AP are divided into time units, so that each cooperative AP can perform frame exchange without affecting other cooperative APs. In this case, the AP in the triggered TXS protocol may be an AP that shares TXOP in multi-AP cooperation operation, and the STA in the triggered TXS protocol may be an AP that shares TXOP in multi-AP cooperation operation.

[0155] In the present disclosure, an AP that shares a TXOP may be referred to as a SAP (sharing AP), and an AP that receives a TXOP from a SAP may be referred to as a DAP (shared AP). Here, the term SAP does not limit the entity that shares a TXOP to only AP STAs, and a SAP may also include non-AP STAs that share a TXOP. In addition, the term DAP does not limit the entity that shares a TXOP to only AP STAs, and a DAP may also include non-AP STAs that share a TXOP (or transmit and receive with an AP STA that shares a TXOP).

[0156] Additionally, frame exchange performed by a DAP with a non-AP STA or SAP belonging to the DAP BSS during the allocated time (i.e., the allocated period for the DAP within the TXOP indicated by the MU-RTS TXS TF transmitted from the SAP, which is the time allocated in the MU-RTS TXS TF) may be referred to as a BSS frame exchange (FE) of the DAP. For example, RTS / CTS frame exchange between the DAP and the non-AP STA followed by data frame transmission and block ACK frame response, UL data frame transmission of non-AP STAs by a trigger frame transmitted from the DAP, and / or data frame transmission of the DAP by a trigger frame transmitted from the SAP may be performed.

[0157] In the present disclosure, "frame exchange (FE)" may include frame transmission and / or reception operations between STAs. The STAs may be APs or non-AP STAs. Here, the frames may include various types of frames (e.g., data frames, control frames, management frames).

[0158] Figure 11 shows an example of multi-AP operation based on Co-TDMA between APs.

[0159] Referring to Fig. 11, SAP and non-AP STA1 may belong to BSS1, and DAP and non-AP STA2 may belong to BSS2. SAP may acquire TXOP and share TXOP with DAP by transmitting MU-RTS TXS TF including information about allocation period within TXOP (time allocated in MU-RTS TXS TF in Fig. 11). DAP may transmit CTS in response to MU-RTS TXS TF and perform frame exchange with non-AP STA2 belonging to its BSS (i.e., BSS2) in the allocation period shared from SAP. Although not shown, after frame exchange is completed (or after allocation period ends), DAP may transmit TXOP return frame to return TXOP to SAP. After frame exchange is completed within a TXOP (or after the allocation period ends), there may be a remaining TXOP period, and the SAP may perform frame exchange with a non-AP STA1 belonging to its own BSS (i.e., BSS1) within the remaining TXOP period.

[0160] In order for multi-AP cooperation to be achieved between two APs, the two APs must be in a connected / bonded state, and / or a negotiation procedure must be performed in advance to exchange cooperation request frames / cooperation response frames containing capability information / requirement information of each AP, and then multi-AP transmission (e.g., Co-TDMA (coordinated time division multiple access), C-OFDMA (coordinated orthogonal frequency division multiple access), Co-SR (coordinated spatial reuse), Co-BF (coordinated beamforming), AP selection, or Jo-TX (joint transmission)) can be performed based on the obtained information. That is, in order for multi-AP transmission to be performed smoothly, a negotiation procedure for configuring / managing multi-AP cooperation and / or transmitting based on a specific multi-AP cooperation method must be performed in advance between the above-described SAP and DAP. A multi-AP set can be set up / configured based on the negotiation procedure. Therefore, the negotiation procedure may also be referred to as a multi-AP set setup / configuration procedure.

[0161] FIG. 12 illustrates an example of a multi-AP negotiation procedure according to an embodiment of the present disclosure.

[0162] Referring to FIG. 12, AP 1 can perform a multi-AP negotiation procedure (or a negotiation procedure for multi-AP cooperation) with AP 2. In the negotiation procedure, AP 1 can transmit a coordination request frame including capability information of AP 1, and AP 2 can transmit a coordination response frame including capability information of AP 2. If AP 2 accepts the cooperation request, the coordination response frame can include information indicating such acceptance, and a cooperation setup for multi-AP cooperation (or a (multi-AP) cooperation setup for AP 1 and AP 2) can be established between AP 1 and AP 2. That is, if the negotiation procedure is successfully completed (or if a cooperation response frame is transmitted / received), a cooperation setup for multi-AP cooperation can be established between AP 1 and AP 2. The cooperative setting can be set to be supported by both AP 1 and AP 2 based on the capability information of AP 1 and the capability information of AP 2, and can include at least one of the information included in the capability information of AP 1 or the information included in the capability information of AP 2.

[0163] Additionally, if the negotiation procedure is successfully completed, a multi-AP set / group including AP 1 and AP 2 may be established (or a multi-AP set / group configuration may be established). Accordingly, the negotiation procedure may include at least one of a procedure for establishing a cooperation configuration for multi-AP cooperation or a procedure for establishing a multi-AP set / group (or a multi-AP set / group configuration). In the present disclosure, a multi-AP set / group may also be referred to as a cooperation group.

[0164] After AP 1 performs a multi-AP negotiation procedure with AP 2, AP 1 can perform a multi-AP negotiation procedure with AP 3 in a similar manner. Upon successful completion of the negotiation procedure: i) a (multi-AP) cooperation configuration is established for AP 1, AP 2, and AP 3 (or for each pair among AP 1, AP 2, and AP 3), and ii) a multi-AP set / group including AP 1, AP 2, and AP 3 can be established (or a multi-AP set / group configuration can be established).

[0165] As described above, when an AP performs a multi-AP negotiation procedure with one or more other APs, and the negotiation procedure is successfully completed: i) a (multi-AP) cooperation configuration is established for the APs that performed the negotiation procedure (or for each pair of APs that performed the negotiation procedure), and ii) a multi-AP set / group including the APs that performed the negotiation procedure may be established (or a multi-AP set / group configuration may be established).

[0166] For successful multi-AP cooperation, a multi-AP selection procedure (or AP selection procedure for multi-AP cooperation) may be performed to select a DAP with which the SAP wishes to share TXOPs within a multi-AP set established / configured through a negotiation procedure and / or to notify that the TXOPs will be shared. Through the multi-AP selection procedure, the SAP can determine whether a DAP requires TXOP sharing within the acquired TXOPs, and if a specific DAP does not require TXOP sharing, it can decide to share the TXOPs with subsequent / other DAPs. Alternatively, the SAP can simply notify the target DAPs that it intends to share TXOPs during the multi-AP selection procedure, thereby enabling multi-AP cooperation to be performed while reducing the overhead caused by the multi-AP selection procedure.

[0167] FIG. 13 illustrates an example of a multi-AP selection procedure according to an embodiment of the present disclosure.

[0168] Referring to FIG. 13, in a multi-AP selection procedure, a SAP may transmit a request frame (i.e., a request frame for AP selection / selection request frame) to one or more DAPs to select a DAP with which to share a TXOP from a multi-AP set established / configured through a negotiation procedure, and one or more DAP(s) receiving the request frame may transmit a response frame (i.e., a response frame for AP selection / selection response frame) to the request frame based on whether TXOP sharing is required. If a response frame including an indication that TXOP sharing is not required is received from a DAP(s), or if a response frame is not received from a DAP(s), the SAP may transmit a request frame for AP selection to another DAP - i.e., the SAP may perform AP reselection. Alternatively, the SAP may simply inform the target DAP(s) that it intends to share a TXOP in the multi-AP selection procedure. For example, a SAP can send an AP selection request frame that does not solicit a response frame to the target DAP with which it wishes to share a TXOP, and the DAP receiving such an AP selection request frame can prepare an action for the intended TXOP sharing.

[0169] The SAP transmits a frame for TXOP sharing (e.g., TXOP sharing frame / MU-RTS TXS trigger frame) to the selected DAP through a multi-AP selection procedure, and the DAP can exchange frames with non-AP STA(s) associated with the DAP within the time period (e.g., allocation period) allocated by the TXOP sharing frame.

[0170] In this disclosure, multi-AP selection may be used interchangeably with schedule announcement, coordination announcement, and cooperative polling.

[0171] Meanwhile, each AP can perform negotiation and / or agreement procedures for multi-AP cooperation with surrounding APs, and establish / configure a multi-AP group and / or multi-AP set based on the negotiation and / or agreement. A multi-AP group / set represents a group / set of APs that are in a cooperative relationship to perform multi-AP cooperation-based transmission (or, multi-AP operation).

[0172] Figure 14 shows an example of the topology of APs.

[0173] Referring to FIG. 14, when AP 2 establishes multi-AP cooperation with AP 1 and AP 3, a multi-AP group / set including AP 1 and AP 3 can be established / configured based on various grouping methods.

[0174] Among the multi-AP cooperation-based transmission methods (or cooperation methods) (e.g., C-SR, C-BF, C-TDMA), C-TDMA is a cooperation method that performs cooperation based on time. Therefore, the SAP allocates time to a DAP, and during that time, the DAP can exchange frames with STAs within its BSS. At this time, other DAP(s) in the cooperation relationship can i) defer channel access if the NAV is set, and ii) initiate a random backoff procedure for the medium determined to be idle if the NAV is not set. In other words, other DAP(s) and neighboring STAs in the cooperation relationship that do not have the NAV set by the DAP that has received the time allocated from the SAP can occupy the channel during the allocated time, which may cause the SAP's TXOP return to fail. In addition, depending on the topology between APs that have established multi-AP cooperation, APs with less interference with each other may not cause frame collisions even if they exchange frames at the same time (or simultaneously).

[0175] Accordingly, the present disclosure proposes a method for simultaneous TXOP sharing and / or a device implementing the method to increase channel utilization and protect TXOP return of SAP in multi-AP operation (e.g., C-TDMA operation). For example, in the case where there are DAPs (e.g., AP 1 and AP 3) with little interference with each other, as in the topology of FIG. 14, AP 2, which acts as an SAP, can share TXOP with two or more DAPs simultaneously. By simultaneously allocating time to two or more DAPs according to various embodiments of the present disclosure, medium utilization in multi-AP operation (e.g., C-TDMA operation) can be improved. In addition, by simultaneously allocating time to two or more DAPs, the SAP can prevent neighboring STAs from occupying the medium until the TXOP return, thereby ensuring that the TXOP return is successfully performed.

[0176] The specific designations (names) proposed in this disclosure may be changed and are not limited thereto.

[0177] FIG. 15 illustrates an example of a method performed by a first AP for TXOP sharing according to an embodiment of the present disclosure.

[0178] Referring to FIG. 15, in step S1501, the first AP can receive information about a cooperation group related to the second AP from the second AP.

[0179] In step S1503, the first AP may determine, based on information about the cooperation group associated with the second AP, whether the third AP belonging to the cooperation group associated with the first AP belongs to the cooperation group associated with the second AP.

[0180] In step S1505, the first AP may transmit a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to a cooperation group associated with the second AP.

[0181] In step S1507, after transmitting a cooperation notification frame to the second AP and the third AP, the first AP may transmit a TXOP shared frame to the second AP and the third AP, the TXOP shared frame including information about a first allocation period assigned to the second AP within the TXOP period and information about a second allocation period assigned to the third AP within the TXOP period. At least a portion of the first allocation period may overlap with the second allocation period.

[0182] According to various embodiments, a first AP may perform a negotiation procedure for multi-AP cooperation with a second AP. Information about the cooperation group associated with the second AP may be received during the negotiation procedure.

[0183] According to various embodiments, information about the cooperative group associated with the second AP may include a list of identification information for one or more APs belonging to the cooperative group associated with the second AP. To determine whether the third AP belongs to the cooperative group associated with the second AP, the first AP may determine whether identification information for the third AP is included in the list of identification information for one or more APs.

[0184] According to various embodiments, based on the identification information for the third AP being included in the identification information list for one or more APs, the third AP may belong to a cooperative group associated with the second AP. Based on the identification information for the third AP not being included in the identification information list for one or more APs, the third AP may not belong to a cooperative group associated with the second AP.

[0185] According to various embodiments, the identification information for the third AP may include at least one of a basic service set (BSS) identifier (ID) associated with the third AP, a BSS color associated with the third AP, an ID of a cooperative group to which the third AP belongs, or an AP ID assigned to the third AP within the cooperative group to which the third AP belongs. The list of identification information for one or more APs may include identification information for each of the one or more APs.

[0186] According to various embodiments, the cooperation announcement frame may include information regarding simultaneous TXOP sharing for the second AP and the third AP. The information regarding simultaneous TXOP sharing may indicate that allocation periods that at least partially overlap will be allocated for the second AP and the third AP.

[0187] According to various embodiments, the first AP may receive a response frame to a cooperation announcement frame from the second AP and a response frame to a cooperation announcement frame from the third AP. The TXOP shared frame may be transmitted after the response frames are received from both the second AP and the third AP.

[0188] According to various embodiments, the TXOP shared frame may be addressed to multiple APs, including a second AP and a third AP.

[0189] According to various embodiments, the value of the first allocation period field including information about the first allocation period and the value of the second allocation period field including information about the second allocation period may be the same.

[0190] According to various embodiments, the value of the first allocation period field, which includes information about the first allocation period, and the value of the second allocation period field, which includes information about the second allocation period, may be different. The first AP may transmit an instruction for returning a TXOP to at least one of the second AP or the third AP.

[0191] FIG. 16 illustrates an example of a method performed by a second AP for TXOP sharing according to an embodiment of the present disclosure.

[0192] Referring to FIG. 16, in step S1601, the second AP can transmit information about a cooperative group associated with the second AP to the first AP.

[0193] In step S1603, the second AP may receive a cooperation announcement frame from the first AP based on the fact that the third AP belonging to the cooperation group associated with the first AP does not belong to the cooperation group associated with the second AP.

[0194] In step S1605, after receiving a cooperation notification frame from the first AP, the second AP may receive a TXOP shared frame from the first AP, which includes information about a first allocation period assigned to the second AP within a TXOP period and information about a second allocation period assigned to the third AP within the TXOP period. At least a portion of the first allocation period may overlap with the second allocation period.

[0195] In step S1607, the second AP may perform frame exchange with one or more STAs connected to the second AP in the first allocation period.

[0196] According to various embodiments, the second AP may perform a negotiation procedure for multi-AP cooperation with the first AP. Information about the cooperation group associated with the second AP may be transmitted during the negotiation procedure.

[0197] According to various embodiments, information about a cooperative group associated with a second AP may include a list of identification information about one or more APs belonging to the cooperative group associated with the second AP.

[0198] According to various embodiments, based on the identification information for the third AP being included in the identification information list for one or more APs, the third AP may belong to a cooperative group associated with the second AP. Based on the identification information for the third AP not being included in the identification information list for one or more APs, the third AP may not belong to a cooperative group associated with the second AP.

[0199] According to various embodiments, the identification information for the third AP may include at least one of a basic service set (BSS) identifier (ID) associated with the third AP, a BSS color associated with the third AP, an ID of a cooperative group to which the third AP belongs, or an AP ID assigned to the third AP within the cooperative group to which the third AP belongs. The list of identification information for one or more APs may include identification information for each of the one or more APs.

[0200] According to various embodiments, the cooperation announcement frame may include information regarding simultaneous TXOP sharing for the second AP and the third AP. The information regarding simultaneous TXOP sharing may indicate that allocation periods that at least partially overlap will be allocated for the second AP and the third AP.

[0201] Below, detailed implementation examples of TXOP sharing are described.

[0202] The present disclosure proposes a simultaneous TXS method for simultaneously allocating time to two or more DAPs and / or a device implementing the method. For example, an AP acting as a SAP can select two or more DAPs from among its partner APs to perform simultaneous TXS. For example, the AP acting as a SAP can simultaneously allocate time to the two or more selected DAPs.

[0203] 1. How to select a DAP

[0204] In some implementations, APs wishing to participate in multi-AP cooperation can perform negotiation procedures for multi-AP cooperation (e.g., exchange negotiation / cooperation request / response frames) with neighboring APs that have the corresponding capabilities (e.g., support at least one cooperation mode). The APs can obtain information about each other by exchanging information about various operational parameters and / or supported (cooperation) modes for multi-AP cooperation-based transmission (or multi-AP operation). An AP that acquires a TXOP and acts as a SAP can select / decide two or more DAPs to perform simultaneous TXS based on the negotiation information for multi-AP cooperation.

[0205] (1) DAP selection method based on (pre-)negotiated information

[0206] In the present disclosure, (pre-)negotiated information (or pre-negotiated information) may refer to information (e.g., capability information) exchanged in a negotiation process.

[0207] For example, in a negotiation procedure for multi-AP cooperation, APs can transmit BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of surrounding APs with which they have established multi-AP cooperation. That is, in a negotiation procedure between a first AP and a second AP, the first AP can obtain the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of a third AP with which it has established multi-AP cooperation (or belongs to a cooperation group related to the second AP). In addition, the second AP can obtain the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of a fourth AP with which it has established multi-AP cooperation (or belongs to a cooperation group related to the first AP) in a negotiation procedure with the first AP. Here, the multi-AP ID (or multi-AP group ID) may be an ID newly defined and / or designed for multi-AP cooperation.

[0208] Accordingly, the first AP can compare the BSSID, BSS color information and / or multi-AP ID (or multi-AP group ID) of the third AP received from the second AP with the BSSID, BSS color information and / or multi-AP ID (or multi-AP group ID) of the fourth AP with which it cooperates to determine whether the third AP and the fourth AP are the same. That is, each AP can determine, in the negotiation procedure for multi-AP cooperation, whether the target AP is also in a cooperative relationship with an AP with which it is already in a cooperative relationship. In addition, each AP can identify the topology of the APs with which it has established cooperation and whether the APs are adjacent.

[0209] For example, if the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the third AP that the first AP receives from the second AP is identical to the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the fourth AP that it cooperates with (i.e., the third AP and the fourth AP are identical to each other), the first AP may determine that the fourth AP and the second AP that it cooperates with are adjacent to each other. As another example, if the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the third AP that the first AP receives from the second AP is different from the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the fourth AP that it cooperates with (i.e., the third AP and the fourth AP are different from each other), the first AP may determine that the fourth AP and the second AP that it cooperates with are not adjacent to each other.

[0210] Based on this (pre-)negotiated information and / or information about the cooperative relationship between DAPs, the SAP can check whether the target DAPs participate in multi-AP operation (e.g., C-TDMA operation) by sending a cooperation announcement frame (or multi-AP selection, schedule announcement frame) to non-adjacent DAPs. At this time, the frame may contain one or more indication bits for simultaneous TXS operation and / or user information fields for the DAPs.

[0211] (2) DAP selection method based on responses from DAPs

[0212] For example, a SAP can check whether two or more DAPs in a cooperative relationship participate in multi-AP operation (e.g., C-TDMA operation) by transmitting a cooperation announcement frame (or multi-AP selection, schedule announcement frame) to the target DAPs. At this time, the frame may contain one or more indication bits for simultaneous TXS operation and / or one or more user information fields for the DAPs. DAPs that receive the cooperation announcement frame and identify that the bit indicating simultaneous TXS is 1 (i.e., simultaneous TXS is enabled (enabled)) can decode other user information field(s) in addition to the user information field containing its own corresponding AID value and obtain AID information. The DAPs can determine whether the acquired AID information for the other DAP(s) matches the AID information for the APs in a cooperative relationship with themselves, and transmit a response frame containing fields / bitmaps / bits indicating their own multi-AP cooperative relationship with the other DAP(s) in response to the cooperation announcement frame.

[0213] That is, the first AP acting as a SAP can transmit a cooperation announcement frame including the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the second and third APs in a cooperative relationship with it. The second and third APs receiving the cooperation announcement frame can identify the cooperative relationship with the corresponding AP based on the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) information that may be included in the AID12 field of the user information field of the other AP in addition to the user information field for itself. Specifically, the second AP can decode the AID12 field of the user information field including the information of the third AP to determine whether the value included in the AID12 field matches the BSSID, BSS color information, and / or multi-AP ID (or multi-AP group ID) of the APs in a cooperative relationship with it. The second AP, which determines whether there is a match, can transmit a response frame including a field, a bitmap, and / or bits indicating the cooperative relationship with the third AP to the first AP.

[0214] Therefore, the SAP can determine whether to perform simultaneous TXS based on the report on the cooperative relationship between the target DAPs contained in the response frame to the cooperative announcement frame transmitted from two or more DAPs. Furthermore, the SAP can identify the cooperative relationship of each DAP based on the information obtained from the DAPs and utilize the information on the cooperative relationship of each DAP as (pre-)negotiated information. That is, the SAP that has identified the cooperative relationship between DAPs can subsequently initiate simultaneous TXS and / or C-TDMA only for DAPs that are not in a cooperative relationship.

[0215] 2. Simultaneous TXS method

[0216] FIG. 17 illustrates an example of a simultaneous TXS procedure according to an embodiment of the present disclosure. The simultaneous TXS procedure (or simultaneous time allocation procedure) illustrated in FIG. 17 can be applied to C-TDMA.

[0217] Referring to Figure 17, each AP can perform a pre-negotiation procedure for multi-AP cooperation. For example, AP 1 performs a pre-negotiation procedure for multi-AP cooperation with AP 2 and AP 3, but AP 2 and AP 3 may not perform the negotiation procedure with each other due to topology. AP 1, which acquires a TXOP and acts as an SAP, can select at least one DAP based on (pre-)negotiated information and / or responses from DAPs and perform a simultaneous TXS.

[0218] For example, a SAP can check whether non-adjacent DAPs will participate in C-TDMA operation by transmitting a cooperation announcement frame (or multi-AP selection, schedule announcement frame) based on pre-negotiation information and / or cooperation relationships between DAPs. At this time, the cooperation announcement frame may contain one or more indication bits for simultaneous TXS operation and one or more user information fields for the DAPs, and the DAPs receiving the cooperation announcement frame (e.g., AP 2 and AP 3 in FIG. 17) can identify that simultaneous TXS is to be performed. Thereafter, the target DAPs can transmit a response frame to the cooperation announcement frame, and after completing individual frame exchanges within a scheduled time and / or BSS 1 and / or immediately after transmitting and receiving a response frame to the cooperation announcement frame, they can receive the MU-RTS TXS TF transmitted from the SAP. That is, simultaneous TXS (or simultaneous time allocation) can be performed by transmitting MU-RTS TXS TFs addressed to two or more DAPs. At this time, one or more user information fields may exist in the MU-RTS TXS TF. In addition, the values ​​of the allocation period fields in each user information field may be different from each other. If the values ​​of the allocation period fields for each DAP do not match, a specific DAP may be instructed to perform a TXOP return. Additionally or alternatively, the values ​​of the allocation period fields in each user information field may be the same from each other. If the values ​​of the allocation period fields for each DAP match, the TXOP return may be omitted or only a specific DAP may be instructed to perform a TXOP return.

[0219] Additionally or alternatively, the SAP may check whether two or more DAPs in a cooperative relationship will participate in the C-TDMA operation by transmitting a cooperation announcement frame (or multi-AP selection, schedule announcement frame). At this time, the cooperation announcement frame may have an indication bit for simultaneous TXS operation and one or more user information fields for the DAPs. The DAPs that receive the cooperation announcement frame and identify that the bit indicating simultaneous TXS is 1 (i.e., enabled) may decode other user information field(s) in addition to the user information field containing the AID value corresponding to themselves and obtain AID information. The corresponding DAPs (e.g., AP 2 and AP 3 in FIG. 17) may check whether the AID information for the other DAP(s) they have obtained matches the AID information for the APs in a cooperative relationship with themselves, and transmit a response frame to the cooperation announcement frame, the response frame including fields and / or bitmaps and / or bits indicating the multi-AP cooperative relationship with the other DAP(s) included in the cooperation announcement frame. That is, in FIG. 17, AP 2 can transmit a response frame including fields and / or bitmaps and / or bits indicating a cooperative relationship with AP 3, and AP 3 can transmit a response frame including fields and / or bits indicating a cooperative relationship with AP 2 to AP 1 (i.e., SAP). The SAP that receives the response frame can decide whether to perform simultaneous TXS based on the relationship between the two APs. At this time, if the two targeted APs (i.e., AP 2 and AP 3) are in a cooperative relationship, it can retransmit the cooperation announcement frame to discover new target APs, or decide to perform TXS targeting a single DAP rather than simultaneous TXS. After this, the SAP can transmit the MU-RTS TXS TF for simultaneous TXS after terminating individual frame exchanges within the scheduled time or BSS 1, or immediately after receiving a response frame to the cooperation announcement frame.That is, the MU-RTS TXS TF can be addressed to two or more DAPs. There can be one or more user information fields in the MU-RTS TXS TF. In addition, the values ​​of the allocation period fields in each user information field can be different. If the values ​​of the allocation period fields for each DAP do not match, a specific DAP can be instructed to perform a TXOP return. Additionally or alternatively, the values ​​of the allocation period fields in each user information field can be the same. If the values ​​of the allocation period fields for each DAP match, the TXOP return can be omitted or only a specific DAP can be instructed to perform a TXOP return.

[0220] The present disclosure proposes a method for simultaneous TXOP sharing and / or a device implementing the method to improve channel utilization and protect TXOP returns of SAPs in multi-AP operations (e.g., C-TDMA operations). For example, the present disclosure provides a method for an AP acting as an SAP to select two or more DAPs among cooperating APs to perform simultaneous TXS and a device implementing the method. For example, the present disclosure provides a method for simultaneously allocating time to two or more DAPs selected according to the above-described DAP selection method and a device implementing the method. By simultaneously allocating time to two or more DAPs, medium utilization in C-TDMA operations can be improved. In addition, by simultaneously allocating time to two or more DAPs, the SAP can be protected by frame exchange between the corresponding DAPs until the TXOP return time.

[0221] The technical features of the present disclosure described above can be applied to various devices and methods. For example, the technical features of the present disclosure described above can be performed / supported by the devices of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above can be applied only to a portion of FIG. 1 and / or FIG. 5. For example, the technical features of the present disclosure described above can be implemented based on the processing chip (114, 124) of FIG. 1, or based on the processor (111, 121) and memory (112, 122) of FIG. 1, or based on the processor (510) and memory (520) of FIG. 5.

[0222] For example, the processor (121) and / or the processing chip (124) of FIG. 1 may be configured to execute instructions stored in the memory (122) to perform operations performed by the first AP in the present disclosure. The operations include: receiving, from a second AP, information about a cooperation group associated with the second AP; determining, based on the information about the cooperation group associated with the second AP, whether a third AP belonging to the cooperation group associated with the first AP belongs to a cooperation group associated with the second AP; transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to the cooperation group associated with the second AP; And after transmitting the cooperation notification frame to the second AP and the third AP, the method includes transmitting a TXOP shared frame to the second AP and the third AP, the TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP period and information about a second allocation period assigned to the third AP within the TXOP period, wherein at least a part of the first allocation period overlaps with the second allocation period.

[0223] For example, the processor (111), the processing chip (114) of FIG. 1, and / or the processor (510) of FIG. 5 may be configured to execute instructions stored in the memory (112, 520) to perform operations performed by an STA associated with a second AP in the present disclosure. The operations include: transmitting information about a cooperation group associated with the second AP to a first AP; receiving a cooperation announcement frame from the first AP based on a third AP belonging to a cooperation group associated with the first AP not belonging to a cooperation group associated with the second AP; receiving, after receiving the cooperation announcement frame from the first AP, a TXOP shared frame from the first AP, the TXOP shared frame including information about a first allocation period assigned to the second AP during a TXOP period and information about a second allocation period assigned to the third AP within the TXOP period; And includes an operation of performing frame exchange with one or more STAs (stations) associated with the second AP during the first allocation period, wherein at least a portion of the first allocation period overlaps with the second allocation period.

[0224] The technical features of the present disclosure can be implemented based on a computer-readable medium (CRM). For example, the CRM proposed by the present disclosure is at least one computer-readable recording medium containing instructions that are executed by at least one processor.

[0225] For example, the CRM may be the memory (122) of FIG. 1 and / or a separate external memory / storage medium / disk. The CRM may store commands that perform operations performed by the first AP in the present disclosure based on being executed by a processor (e.g., the processor (121) and / or the processing chip (124) of FIG. 1). The operations include: receiving, from a second AP, information about a cooperation group associated with the second AP; determining, based on the information about the cooperation group associated with the second AP, whether a third AP belonging to the cooperation group associated with the first AP belongs to a cooperation group associated with the second AP; transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to the cooperation group associated with the second AP; And after transmitting the cooperation notification frame to the second AP and the third AP, the method includes transmitting a TXOP shared frame to the second AP and the third AP, the TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP period and information about a second allocation period assigned to the third AP within the TXOP period, wherein at least a part of the first allocation period overlaps with the second allocation period.

[0226] For example, the CRM may be the memory (112) of FIG. 1, the memory (520) of FIG. 5, and / or a separate external memory / storage medium / disk. The CRM may store commands that perform operations performed by an STA associated with a second AP in the present disclosure based on being executed by a processor (e.g., the processor (111), the processing chip (114) of FIG. 1, and / or the processor (510) of FIG. 5). The operations include: transmitting information about a cooperation group associated with the second AP to the first AP; receiving a cooperation announcement frame from the first AP based on the fact that a third AP belonging to the cooperation group associated with the first AP does not belong to the cooperation group associated with the second AP; An operation of receiving, from the first AP, a TXOP (transmission opportunity) shared frame including information about a first allocation period allocated to the second AP and information about a second allocation period allocated to the third AP within the TXOP period after receiving the cooperation notification frame from the first AP; and an operation of performing frame exchange with one or more STAs (stations) associated with the second AP during the first allocation period, wherein at least a portion of the first allocation period overlaps with the second allocation period.

[0227] The technical features of the present disclosure described above are applicable to various applications and business models. For example, the technical features described above can be applied to wireless communication in devices that support artificial intelligence (AI).

[0228] Artificial intelligence (AI) is the study of artificial intelligence or the methodologies for creating it, while machine learning (ML) defines various problems in the field of AI and studies the methodologies for solving them. Machine learning is also defined as an algorithm that improves performance on a task through consistent experience.

[0229] An artificial neural network (ANN) is a model used in machine learning. It can refer to a model with problem-solving capabilities, consisting of artificial neurons (nodes) formed by the connection of synapses to form a network. An ANN can be defined by the connection patterns between neurons in different layers, the learning process that updates model parameters, and the activation function that generates output values.

[0230] An artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer contains one or more neurons, and the artificial neural network may include synapses connecting neurons. In an artificial neural network, each neuron can output a function value of an activation function based on input signals, weights, and biases received through the synapses.

[0231] Model parameters are parameters determined through learning, including synaptic connection weights and neuron biases. Hyperparameters are parameters that must be set before learning in machine learning algorithms, including the learning rate, number of iterations, mini-batch size, and initialization function.

[0232] The goal of artificial neural network training can be seen as determining model parameters that minimize a loss function. The loss function can be used as an indicator for determining optimal model parameters during the artificial neural network training process.

[0233] Machine learning can be classified into supervised learning, unsupervised learning, and reinforcement learning depending on the learning method.

[0234] Supervised learning refers to a method for training an artificial neural network when given labels for the training data. The labels can refer to the correct answer (or output value) that the artificial neural network must infer when the training data is input to the artificial neural network. Unsupervised learning can refer to a method for training an artificial neural network when the training data is not given labels. Reinforcement learning can refer to a learning method in which an agent defined within a given environment is trained to select actions or action sequences that maximize the cumulative reward in each state.

[0235] Machine learning implemented with a deep neural network (DNN) containing multiple hidden layers among artificial neural networks is also called deep learning, and deep learning is a subset of machine learning. Hereinafter, the term "machine learning" is used to encompass deep learning.

[0236] Additionally, the above-described technical features can be applied to wireless communication of robots.

[0237] A robot can be defined as a machine that automatically performs or operates a given task based on its own capabilities. Specifically, a robot capable of perceiving its environment, making independent judgments, and performing actions can be called an intelligent robot.

[0238] Robots can be categorized into industrial, medical, household, and military applications based on their intended use or field. Robots are equipped with actuators or motors, enabling them to perform various physical actions, such as moving robot joints. Furthermore, mobile robots incorporate wheels, brakes, and propellers into their actuators, enabling them to move on the ground or fly in the air.

[0239] Additionally, the above-described technical features can be applied to devices that support extended reality.

[0240] Extended reality is a general term for virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology presents real-world objects and backgrounds as CG images only, AR technology presents virtual CG images over images of real objects, and MR technology is a computer graphics technology that blends and combines virtual objects with the real world.

[0241] MR technology is similar to AR in that it presents both real and virtual objects simultaneously. However, while AR uses virtual objects to complement real objects, MR uses virtual and real objects on an equal footing.

[0242] XR technology can be applied to HMD (Head-Mount Display), HUD (Head-Up Display), mobile phones, tablet PCs, laptops, desktops, TVs, digital signage, etc., and devices to which XR technology is applied can be called XR devices.

[0243] The present disclosure may have various advantageous effects.

[0244] For example, medium utilization in multi-AP operations (e.g., C-TDMA operations) can be improved by simultaneously allocating time to two or more DAPs. Furthermore, by simultaneously allocating time to two or more DAPs, the SAP can prevent neighboring STAs from occupying the medium until the TXOP is released (i.e., the successful release of the TXOP can be guaranteed).

[0245] The beneficial effects that can be achieved through specific embodiments of the present disclosure are not limited to the beneficial effects listed above. For example, various technical effects may be understood and / or derived from the present disclosure by those skilled in the art. Therefore, the specific effects of the present disclosure are not limited to those explicitly described herein, but may include various effects that can be understood or derived from the technical features of the present disclosure.

[0246] The claims set forth in this disclosure may be combined in various ways. For example, the technical features of the method claims of this disclosure may be combined and implemented as a device, and the technical features of the device claims of this disclosure may be combined and implemented as a method. Furthermore, the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined and implemented as a device, and the technical features of the method claims of this disclosure and the technical features of the device claims of this disclosure may be combined and implemented as a method.

Claims

1. A step in which a first AP (access point) receives information about a cooperation group related to the second AP from a second AP; A step of determining, based on information about a cooperation group associated with the second AP, whether a third AP belonging to a cooperation group associated with the first AP belongs to a cooperation group associated with the second AP; A step in which the first AP transmits a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to a cooperation group associated with the second AP; and A step of transmitting a TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP (transmission opportunity) period and information about a second allocation period assigned to the third AP within the TXOP period, to the second AP and the third AP after the first AP transmits the cooperation notification frame to the second AP and the third AP, A method wherein at least a portion of the first allocation period overlaps with the second allocation period.

2. In claim 1, the first AP further includes a step of performing a negotiation procedure for multi-AP cooperation with the second AP, Information about the cooperative group related to the above second AP is received in the above negotiation procedure.

3. In claim 1, the information about the cooperative group associated with the second AP may include a list of identification information about one or more APs belonging to the cooperative group associated with the second AP.

4. In claim 3, based on the identification information for the third AP being included in the list of identification information for one or more APs, the third AP belongs to a cooperative group related to the second AP, A method in which the third AP does not belong to a cooperative group associated with the second AP based on the identification information for the third AP not being included in the list of identification information for one or more of the APs.

5. In claim 3, the identification information for the third AP includes at least one of a BSS (basic service set) ID (identifier) ​​related to the third AP, a BSS color related to the third AP, an ID of a cooperative group to which the third AP belongs, or an AP ID assigned to the third AP within the cooperative group to which the third AP belongs. A method wherein the list of identification information for the one or more APs includes identification information for each of the one or more APs.

6. In claim 1, the cooperation notification frame includes information about simultaneous TXOP sharing for the second AP and the third AP, A method in which the information about the above simultaneous TXOP sharing indicates that allocation periods that at least partially overlap will be allocated to the second AP and the third AP.

7. In claim 1, the first AP further includes a step of receiving a response frame for the cooperation notification frame from the second AP and a response frame for the cooperation notification frame from the third AP, The above TXOP shared frame is transmitted after receiving response frames from both the second AP and the third AP.

8. A method according to claim 1, wherein the TXOP shared frame is addressed to a plurality of APs including the second AP and the third AP.

9. In claim 1, the value of the first allocation period field including information about the first allocation period and the value of the second allocation period field including information about the second allocation period are the same method.

10. In claim 1, the value of the first allocation period field including information about the first allocation period and the value of the second allocation period field including information about the second allocation period are different, A method further comprising the step of transmitting an instruction for TXOP return to at least one of the second AP or the third AP.

11. In the first AP (access point), Transmitter and receiver; memory; and At least one processor functionally coupled with the transceiver and the memory, The memory stores instructions for performing operations based on being executed by the at least one processor, the operations being: An action of receiving information about a cooperative group associated with the second AP from the second AP; An operation of determining whether a third AP belonging to a cooperation group associated with the first AP belongs to a cooperation group associated with the second AP based on information about the cooperation group associated with the second AP; An operation of transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to a cooperation group associated with the second AP; and After transmitting the cooperation notification frame to the second AP and the third AP, an operation of transmitting a TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP (transmission opportunity) period and information about a second allocation period assigned to the third AP within the TXOP period to the second AP and the third AP is included. A first AP wherein at least a portion of the first allocation period overlaps with the second allocation period.

12. In the device, at least one processor; and At least one memory functionally coupled with at least one processor, The at least one memory stores instructions that perform operations based on being executed by the at least one processor, the operations being: An operation of receiving information about a cooperative group associated with a second AP (access point); An operation of determining whether a third AP belonging to a cooperation group associated with the first AP belongs to a cooperation group associated with the second AP based on information about the cooperation group associated with the second AP; An operation of transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to a cooperation group associated with the second AP; and After transmitting the cooperation notification frame to the second AP and the third AP, an operation of transmitting a TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP (transmission opportunity) period and information about a second allocation period assigned to the third AP within the TXOP period to the second AP and the third AP is included. A device wherein at least a portion of the first allocation period overlaps with the second allocation period.

13. A non-transitory computer readable medium (CRM) storing program code that implements instructions that perform operations based on being executed by at least one processor, wherein the operations are: An operation of receiving information about a cooperative group associated with a second AP (access point); An operation of determining whether a third AP belonging to a cooperation group associated with the first AP belongs to a cooperation group associated with the second AP based on information about the cooperation group associated with the second AP; An operation of transmitting a cooperation announcement frame to the second AP and the third AP based on the third AP not belonging to a cooperation group associated with the second AP; and After transmitting the cooperation notification frame to the second AP and the third AP, an operation of transmitting a TXOP shared frame including information about a first allocation period assigned to the second AP within a TXOP (transmission opportunity) period and information about a second allocation period assigned to the third AP within the TXOP period to the second AP and the third AP is included. A CRM wherein at least a portion of the first allocation period overlaps with the second allocation period.

14. A step in which a second AP (access point) transmits information about a cooperative group related to the second AP to the first AP; A step in which the second AP receives a cooperation announcement frame from the first AP based on the fact that the third AP belonging to the cooperation group associated with the first AP does not belong to the cooperation group associated with the second AP; A step of receiving, from the first AP, a TXOP (transmission opportunity) shared frame including information about a first allocation period assigned to the second AP and information about a second allocation period assigned to the third AP within the TXOP period, after the second AP receives the cooperation notification frame from the first AP; and The second AP includes a step of performing frame exchange with one or more STAs (stations) associated with the second AP during the first allocation period, A method wherein at least a portion of the first allocation period overlaps with the second allocation period.

15. In claim 14, the second AP further includes a step of performing a negotiation procedure for multi-AP cooperation with the first AP, Information about the cooperative group related to the above second AP is transmitted in the above negotiation procedure.

16. In claim 14, the information about the cooperative group associated with the second AP includes a list of identification information about one or more APs belonging to the cooperative group associated with the second AP, A method wherein the step of determining whether the third AP belongs to a cooperative group associated with the second AP comprises the step of determining whether identification information for the third AP is included in a list of identification information for one or more APs.

17. In claim 16, based on the identification information for the third AP being included in the list of identification information for one or more APs, the third AP belongs to a cooperative group related to the second AP, A method in which the third AP does not belong to a cooperative group associated with the second AP based on the identification information for the third AP not being included in the list of identification information for one or more of the APs.

18. In claim 16, the identification information for the third AP includes at least one of a BSS (basic service set) ID (identifier) ​​associated with the third AP, a BSS color associated with the third AP, an ID of a cooperative group to which the third AP belongs, or an AP ID assigned to the third AP within the cooperative group to which the third AP belongs. A method wherein the list of identification information for the one or more APs includes identification information for each of the one or more APs.

19. In claim 14, the cooperation notification frame includes information about simultaneous TXOP sharing for the second AP and the third AP, A method in which the information about the above simultaneous TXOP sharing indicates that allocation periods that at least partially overlap will be allocated to the second AP and the third AP.

20. In a STA (station) connected to a second AP (access point), Transmitter and receiver; memory; and At least one processor functionally coupled with the transceiver and the memory, The memory stores instructions for performing operations based on being executed by the at least one processor, the operations being: An action of transmitting information about a cooperative group associated with the second AP to the first AP; An operation of receiving a cooperation announcement frame from the first AP based on the fact that a third AP belonging to a cooperation group associated with the first AP does not belong to a cooperation group associated with the second AP; An operation of receiving a TXOP shared frame from the first AP, the TXOP shared frame including information about a first allocation period allocated to the second AP during the TXOP period and information about a second allocation period allocated to the third AP within the TXOP period, after receiving the cooperation notification frame from the first AP; and Including an operation of performing frame exchange with one or more STAs (stations) associated with the second AP during the first allocation period, A second AP wherein at least a portion of the first allocation period overlaps with the second allocation period.

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