WO2024262849A1 - Method and device for communication in interference situation in wireless lan system - Google Patents

Abstract

The present disclosure relates to communication in an interference situation in a wireless LAN system. This operating method of an access point (AP) comprises the steps of: receiving one or more data frames from a first station (STA); transmitting one or more control frames to one or more stations (STA) including the first STA; and performing an operation related to a transmit opportunity (TXOP) of the first STA, wherein one from among the one or more data frames can include information related to the TXOP of the first STA.

Description

Method and device for communication in interference situations in wireless LAN systems

The present disclosure relates to a wireless LAN system, and more particularly, to a method and device for communication in an interference situation in a wireless LAN system.

Recently, as the spread of mobile devices has expanded, wireless LAN (Wireless Local Area Network) technology that can provide fast wireless communication services to mobile devices has been receiving a lot of attention. Wireless LAN technology is a technology that allows mobile devices such as smart phones, smart pads, laptop computers, portable multimedia players, and embedded devices to wirelessly access the Internet based on short-range wireless communication technology.

As applications requiring higher throughput and real-time transmission emerge, wireless LANs may support expanded frequency bandwidth and/or efficient retransmission operations. In addition, operations utilizing multiple channels or links simultaneously may be supported.

Meanwhile, the technology that serves as the background for the invention was written to promote understanding of the background for the invention, and may include content that is not a prior art already known to a person with ordinary knowledge in the field to which the technology belongs.

The present disclosure provides a method and device for performing smooth communication when interference or communication interruption occurs due to non-wireless LAN or wireless LAN direct communication within a wireless LAN terminal.

The present disclosure provides a method and device for reducing interference when performing non-wireless LAN wireless communication or wireless LAN direct communication in a wireless LAN system.

The technical problems to be achieved in the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present disclosure belongs from the description below.

According to one embodiment of the present disclosure, a method for operating an access point (AP) in a wireless LAN system includes the steps of receiving at least one data frame from a first STA (first station), transmitting at least one control frame to at least one STA (station) including the first STA, and performing an operation related to a TXOP (transmit opportunity) of the first STA, wherein one of the at least one data frame may include information related to the TXOP of the first STA.

According to another embodiment of the present disclosure, a method of operating a first station (STA) in a wireless LAN system includes the steps of obtaining a transmit opportunity (TXOP), transmitting at least one data frame to an access point (AP), receiving at least one control frame from the AP, and performing an operation exclusive to the wireless LAN communication, wherein one of the at least one data frame may include information related to the TXOP.

According to another embodiment of the present disclosure, in a wireless LAN system, a communication node includes a transceiver, and a processor connected to the transceiver, wherein the transceiver receives at least one data frame from a first STA, the transceiver transmits at least one control frame to at least one STA (station) including the first STA, and the processor performs an operation related to a TXOP (transmit opportunity) of the first STA, wherein one of the at least one data frame may include information related to the TXOP of the first STA.

According to another embodiment of the present disclosure, in a wireless LAN system, a communication node includes a transceiver, and a processor connected to the transceiver, wherein the processor obtains a transmit opportunity (TXOP), the transceiver transmits at least one data frame to an access point (AP), the transceiver receives at least one control frame from the AP, and the processor performs an operation exclusive to wireless LAN communication, wherein one of the at least one data frame may include information related to the TXOP.

According to the present disclosure, a wireless LAN terminal and a communication method can be provided that increase the stability of wireless LAN communication by sharing a TXOP (transmit opportunity) with another wireless LAN terminal or terminating it early when a wireless LAN terminal performing non-wireless LAN wireless communication or wireless LAN direct communication does not perform wireless LAN communication.

The effects obtainable from the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by a person skilled in the art to which the present disclosure belongs from the description below.

Figure 1 illustrates a block diagram of a communication node in a wireless LAN system.

Figure 2 illustrates the concept of multiple links established between MLDs (multi link devices) in a wireless LAN system.

Figure 3 illustrates a first embodiment of a communication method when interference occurs in a wireless LAN system.

Figure 4 illustrates a second embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 5a illustrates a third embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 5b illustrates a fourth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 5c illustrates a fifth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 6a illustrates a sixth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 6b illustrates a seventh embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 6c illustrates an eighth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 7a illustrates a ninth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 7b illustrates a tenth embodiment of a communication method when interference occurs in a wireless LAN system.

Figure 8 illustrates an eleventh embodiment of a communication method when interference occurs in a wireless LAN system.

Figure 9 shows an example of A-control information.

FIG. 10 illustrates an operation flow diagram of an AP (access point) according to one embodiment of the present disclosure.

FIG. 11 illustrates an operation flow diagram of a first STA (first station) according to one embodiment of the present disclosure.

FIG. 12 illustrates an operation flow diagram of a second STA (second station) according to one embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present disclosure. However, the present disclosure may be implemented in various different forms and is not limited to the embodiments described herein.

In describing embodiments of the present disclosure, if it is determined that a specific description of a known configuration or function may obscure the gist of the present disclosure, a detailed description thereof will be omitted. In addition, parts in the drawings that are not related to the description of the present disclosure have been omitted, and similar parts have been given similar drawing reference numerals.

In the present disclosure, when a component is said to be "connected", "coupled" or "connected" to another component, this may include not only a direct connection relationship, but also an indirect connection relationship in which another component exists in between. In addition, when a component is said to "include" or "have" another component, this does not exclude the other component unless specifically stated otherwise, but means that the other component can be included.

In this disclosure, the terms first, second, etc. are used only for the purpose of distinguishing one component from another component, and do not limit the order or importance between the components unless specifically stated. Accordingly, within the scope of this disclosure, a first component in one embodiment may be referred to as a second component in another embodiment, and similarly, a second component in one embodiment may be referred to as a first component in another embodiment.

In the present disclosure, the components that are distinguished from each other are intended to clearly explain the characteristics of each, and do not necessarily mean that the components are separated. That is, a plurality of components may be integrated to form a single hardware or software unit, and a single component may be distributed to form a plurality of hardware or software units. Accordingly, even if not mentioned separately, such integrated or distributed embodiments are also included in the scope of the present disclosure.

In the present disclosure, the components described in various embodiments do not necessarily mean essential components, and some may be optional components. Accordingly, an embodiment that consists of a subset of the components described in one embodiment is also included in the scope of the present disclosure. In addition, an embodiment that includes other components in addition to the components described in various embodiments is also included in the scope of the present disclosure.

In this disclosure, each of the phrases "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, C or combination thereof" can include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

The advantages and features of the present disclosure, and the methods for achieving them, will become clearer with reference to the embodiments described in detail below together with the accompanying drawings. However, the present disclosure is not limited to the embodiments presented below, but may be implemented in various different forms, and these embodiments are provided only to make the disclosure of the present invention complete, and to fully inform a person having ordinary skill in the art to which the present invention belongs of the scope of the invention.

Hereinafter, a wireless LAN communication system to which embodiments according to the present invention are applied is described. The wireless LAN communication system to which embodiments according to the present invention are applied is not limited to the contents described below, and the embodiments according to the present invention can be applied to various wireless communication systems. The wireless LAN communication system can be referred to as a "wireless LAN communication network."

Figure 1 illustrates a block diagram of a communication node in a wireless LAN system.

Referring to FIG. 1, a communication node (100) may be an access point (AP), a station (STA), an AP multi-link device (MLD), or a non-AP MLD. STA may mean a non-AP STA. An operating channel width supported by an AP may be 20 MHz (megahertz), 80 MHz, or 160 MHz, etc. An operating channel width supported by an STA may be 20 MHz, 80 MHz, etc.

The communication node (100) may include at least one processor (110), a memory (120), and at least one transceiver (130) that is connected to a network and performs communication. The transceiver (130) may be referred to as a transceiver, an RF (radio frequency) unit, an RF module, etc. In addition, the communication node (100) may further include an input interface device (140), an output interface device (150), a storage device (160), etc. Each component included in the communication node (100) may be connected by a bus (170) and may communicate with each other.

However, each component included in the communication node (100) may be connected through an individual interface or individual bus centered around the processor (110), rather than a common bus (170). For example, the processor (110) may be connected to at least one of the memory (120), the transmission/reception device (130), the input interface device (140), the output interface device (150), and the storage device (160) through a dedicated interface.

The processor (110) can execute a program command stored in at least one of the memory (120) and the storage device (160). The processor (110) may mean a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor in which methods according to embodiments of the present invention are performed. Each of the memory (120) and the storage device (160) may be configured with at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory (120) may be configured with at least one of a read only memory (ROM) and a random access memory (RAM).

Figure 2 illustrates the concept of multiple links established between MLDs in a wireless LAN system.

Referring to FIG. 2, an MLD may have one MAC (medium access control) address. In embodiments, the MLD may refer to an AP MLD and/or a non-AP MLD. The MAC address of the MLD may be used in a multi-link setup procedure between the non-AP MLD and the AP MLD. The MAC address of the AP MLD may be different from the MAC address of the non-AP MLD. AP(s) associated with the AP MLD may have different MAC addresses, and STA(s) associated with the non-AP MLD may have different MAC addresses. APs in the AP MLD with different MAC addresses may be responsible for each link and may perform the role of independent APs.

STAs in a non-AP MLD with different MAC addresses can take charge of each link and perform the role of independent STAs. The non-AP MLD may be referred to as a STA MLD. The MLD may support a STR (simultaneous transmit and receive) operation. In this case, the MLD may perform a transmission operation on link 1 and a reception operation on link 2. An MLD supporting the STR operation may be referred to as a STR MLD (e.g., STR AP MLD, STR non-AP MLD). In the embodiments, a link may mean a channel or a band. A device that does not support the STR operation may be referred to as an NSTR (non-STR) AP MLD or an NSTR non-AP MLD (or, NSTR STA MLD).

The MLD can transmit and receive frames in multiple links by using a non-continuous bandwidth expansion scheme (e.g., 80 MHz + 80 MHz). The multi-link operation can include multi-band transmission. The AP MLD can include multiple APs, and the multiple APs can operate on different links. Each of the multiple APs can perform the function(s) of the lower MAC layer. Each of the multiple APs can be referred to as a "communication node" or a "lower entity." The communication node (i.e., AP) can operate under the control of a higher layer (or, the processor (110) illustrated in FIG. 1). The non-AP MLD can include multiple STAs, and the multiple STAs can operate on different links. Each of the multiple STAs can be referred to as a "communication node" or a "lower entity." The communication node (e.g., STA) can operate under the control of a higher layer (or, the processor (110) illustrated in FIG. 1).

The MLD can perform communications in multi-band. For example, the MLD can perform communications using a 40MHz bandwidth in a 2.4GHz band according to a channel expansion method (e.g., a bandwidth expansion method), and can perform communications using a 160MHz bandwidth in a 5GHz band according to a channel expansion method. The MLD can perform communications using a 160MHz bandwidth in a 5GHz band, and can perform communications using a 160MHz bandwidth in a 6GHz band. One frequency band (e.g., one channel) used by the MLD can be defined as one link. Alternatively, multiple links can be established in one frequency band used by the MLD. For example, the MLD can establish one link in a 2.4GHz band, and two links in a 6GHz band. Each link can be referred to as a first link, a second link, a third link, etc. Alternatively, each link can be referred to as link 1, link 2, link 3, etc. Link numbers can be set by the AP, and each link can be assigned an ID (identifier).

An MLD (e.g., an AP MLD and/or a non-AP MLD) can establish multiple links by performing an access procedure and/or a negotiation procedure for multi-link operation. In this case, the number of links and/or a link to be used among multiple links can be established. A non-AP MLD (e.g., an STA) can check information on a band that can be communicated with the AP MLD. In the negotiation procedure for multi-link operation between the non-AP MLD and the AP MLD, the non-AP MLD can establish one or more links among the links supported by the AP MLD to be used for multi-link operation. An STA (e.g., an IEEE 802.11a/b/g/n/ac/ax STA) that does not support multi-link operation can be connected to one or more links among the multiple links supported by the AP MLD.

When the bandwidth gap between multiple links (e.g., the bandwidth gap between link 1 and link 2 in the frequency domain) is sufficient, the MLD can perform the STR operation. For example, the MLD can transmit PPDU (PLCP (physical layer convergence procedure) protocol data unit) 1 using link 1 among the multiple links, and receive PPDU 2 using link 2 among the multiple links. On the other hand, when the bandwidth gap between the multiple links is insufficient and the MLD performs the STR operation, IDC (in-device coexistence) interference, which is interference between the multiple links, may occur. Therefore, when the bandwidth gap between the multiple links is insufficient, the MLD may not perform the STR operation. The link pair having the above-described interference relationship may be a Non Simultaneous Transmit and Receive (NSTR) limited link pair. Here, the MLD may be an NSTR AP MLD or an NSTR non-AP MLD.

For example, multiple links including link 1, link 2, and link 3 can be established between the AP MLD and the non-AP MLD 1. If the bandwidth gap between link 1 and link 3 is sufficient, the AP MLD can perform the STR operation using link 1 and link 3. That is, the AP MLD can transmit a frame using link 1 and receive a frame using link 3. If the bandwidth gap between link 1 and link 2 is not sufficient, the AP MLD may not perform the STR operation using link 1 and link 2. If the bandwidth gap between link 2 and link 3 is not sufficient, the AP MLD may not perform the STR operation using link 2 and link 3.

Meanwhile, in a wireless LAN system, a negotiation procedure for multi-link operation can be performed in the access procedure between a STA and an AP.

A device (e.g., AP and STA) supporting multiple links may be referred to as a multi-link device (MLD). An AP supporting multiple links may be referred to as an AP MLD, and an STA supporting multiple links may be referred to as a non-AP MLD or a STA MLD. An AP MLD may have a physical address (e.g., MAC address) for each link. The AP MLD may be implemented as if there are separate APs responsible for each link. Multiple APs may be managed within one AP MLD. Therefore, coordination between multiple APs belonging to the same AP MLD may be possible. A STA MLD may have a physical address (e.g., MAC address) for each link. The STA MLD may be implemented as if there are separate STAs responsible for each link. Multiple STAs may be managed within one STA MLD. Therefore, coordination between multiple STAs belonging to the same STA MLD may be possible.

For example, each of AP1 of the AP MLD and STA1 of the STA MLD can be in charge of the first link and can communicate using the first link. Each of AP2 of the AP MLD and STA2 of the STA MLD can be in charge of the second link and can communicate using the second link. STA2 can receive state change information about the first link from the second link. In this case, the STA MLD can collect information (e.g., state change information) received from each link and control an operation performed by STA1 based on the collected information.

Next, methods of transmitting and receiving data in a wireless LAN system will be described. Even if a method (e.g., transmitting or receiving a signal) performed by a first communication node among communication nodes is described, a second communication node corresponding thereto can perform a method (e.g., receiving or transmitting a signal) corresponding to the method performed by the first communication node. That is, when an operation of an STA is described, an AP corresponding thereto can perform an operation corresponding to the operation of the STA. Conversely, when an operation of an AP is described, an STA corresponding thereto can perform an operation corresponding to the operation of the AP. In an embodiment, an operation of an STA can be interpreted as an operation of an STA MLD, an operation of an STA MLD can be interpreted as an operation of an STA, an operation of an AP can be interpreted as an operation of an AP MLD, and an operation of an AP MLD can be interpreted as an operation of an AP.

Figure 3 illustrates a first embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIG. 3, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may also be referred to as a wireless LAN link. The wireless LAN link in which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of the multi-link links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate while being affiliated with an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate while being affiliated with an upper MLD.

STA 1 (103) can perform a channel access procedure on a link. The channel access procedure may be an enhanced distributed channel access (EDCA) backoff operation per AC (access categories). If STA 1 (103) succeeds in the backoff operation (e.g., the EDCA backoff counter per AC reaches 0) and the EDCAF (EDCA Function) per AC of STA 1 (103) determines transmission, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple data frames at predetermined intervals within the TXOP. The predetermined interval may be a Short Inter-Frame Space (SIFS) or an XIFS which is longer or shorter than the SIFS. The XIFS can be shorter than or equal to the PIFS (priority inter-frame space) interval. The data frame can be, for example, a PPDU (physical layer protocol data unit), an MPDU (medium access control layer protocol data unit), or an A-MPDU (aggregated MPDU). STA 1 (103) can transmit a first data frame (300) and a second data frame (302) to AP 1 (101) on the link. The transmission interval of the first data frame (300) and the second data frame (302) can be XIFS, which is SIFS or other interval. Alternatively, a first control frame (304) of AP 1 (101) can be transmitted between the first data frame (300) and the second data frame (302). The control frame may be, for example, one of a BA (block ACK) frame, a CF-End (contention free end) frame, a CTS (clear to send) frame, and an RTS (request to send) frame. Whether the first control frame (304) should be transmitted between data frames or whether the first control frame (304) should be transmitted after the transmission of the last data frame (e.g., the second data frame (302)) may be determined in advance through negotiation. Alternatively, the transmission timing of the first control frame (304) may be indicated by an indicator included in the MAC header included in the first transmitted data frame (e.g., the first data frame (300)).

Before transmitting the second data frame (302), STA 1 (103) may know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) or wireless LAN direct communication will be performed. The non-802.11 wireless communication or wireless LAN direct communication may be performed at a different operating frequency from the link on which the first data frame (300) is transmitted. That is, the non-802.11 wireless communication or wireless LAN direct communication may be performed at a different channel from the channel on which the TXOP acquired by STA 1 (103) is set. STA 1 (103) cannot communicate with AP 1 (101) while performing non-802.11 wireless communication and wireless LAN direct communication. Therefore, STA 1 (103) may want to allow AP 1 (101) to use communication resources while performing non-802.11 wireless communication and wireless LAN direct communication. Accordingly, STA 1 (103) may include TXOP transfer information in the MAC header of the MPDU or A-MPDU included in the second data frame (302). The TXOP transfer information may have, for example, a structure identical to or similar to that illustrated in FIG. 9. The TXOP transfer information may be included in the HT control field of the MAC header in the form of an A-control. Alternatively, the TXOP transfer information may be included in a data frame and transmitted in a form other than the A-control form (e.g., an information element, a bit, a field, or a sub-field). The TXOP transfer information may instruct STA 1 (103) to transfer a TXOP to AP 1 (101). STA 1 (103) may indicate the length of the TXOP transferred in the TXOP transfer information. Alternatively, STA 1 (103) may indicate the length of the TXOP to be transmitted by the duration field of the MAC header, and may indicate the length of time during which wireless LAN communication is unavailable by including the length of time in the TXOP transmission information. Alternatively, the duration field of the MAC header transmitted by STA 1 (103) and the length of the TXOP of STA 1 (103) included in the TXOP transmission information may be the same. The second data frame (302), which is the last frame transmitted by STA 1 (103) to transmit the TXOP, may be transmitted in a format that legacy terminals can recognize (e.g., non-HT PPDU).

AP 1 (101) may respond with a first control frame (304) after receiving the second data frame (302) of STA 1 (103). The first control frame (304) may include all reception status information for data frames received before transmitting the first control frame (304). After AP 1 (101) responds with the first control frame (304), AP 1 (101) may perform communication within a time length included in the TXOP transmission information indicated by STA 1 (103). The time length indicated by STA 1 (103) may be referred to as Transferred TXOP. AP 1 (101) does not transmit frames to STA 1 (103) within the Transferred TXOP. AP 1 (101) may act as a holder of the Transferred TXOP or may perform an operation similar to a TXOP holder. AP 1 (101) may transmit a downlink frame to STA 2 (105). Alternatively, AP 1 (101) may transmit a trigger frame to trigger uplink frame transmission. Alternatively, AP 1 (101) may terminate a TXOP. Terminating a TXOP may be performed, for example, by transmitting a second control frame (e.g., a CF-End frame). Alternatively, terminating a TXOP may also be performed by transmitting a data frame in which the Duration field of the MAC header is indicated as 0.

STA 1 (103) can perform non-802.11 wireless communication or wireless LAN direct communication operation during the time period indicated in the second data frame (302).

FIG. 4 is a diagram illustrating a second embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIG. 4, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may also be referred to as a wireless LAN link. The wireless LAN link in which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of the multi-link links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate in conjunction with an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate in conjunction with an upper MLD.

STA 1 (103) can perform a channel access procedure on the link. The channel access procedure may be an AC-specific EDCA backoff operation. If STA 1 (103) succeeds in the backoff operation (e.g., the AC-specific EDCA backoff counter reaches 0) and the AC-specific EDCAF (EDCA Function) of STA 1 (103) determines transmission, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple data frames within the TXOP at predetermined intervals. The predetermined interval may be SIFS or XIFS which is longer or shorter than SIFS. XIFS may be shorter than or equal to PIFS. The data frame may be, for example, a PPDU, an MPDU, or an A-MPDU. STA 1 (103) may transmit a first data frame (400) and a second data frame (402) to AP 1 (101) over the link. The transmission interval of the first data frame (400) and the second data frame (402) may be SIFS or another interval, XIFS. Alternatively, a first control frame (404) of AP 1 (101) may be transmitted between the first data frame (400) and the second data frame (402). Whether the first control frame (404) should be transmitted between the data frames or after the transmission of the last data frame (e.g., the second data frame (402)) may be determined in advance through negotiation. Alternatively, an indicator may be included in the MAC header included in the first transmitted data frame (e.g., the first data frame (400)) to indicate the time of transmission of the first control frame (404).

Before transmitting the second data frame (402), STA 1 (103) can know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) or wireless LAN direct communication will be performed. Non-802.11 wireless communication or wireless LAN direct communication can be performed at a different operating frequency from the link on which the first data frame (400) is transmitted. That is, Non-802.11 wireless communication or wireless LAN direct communication can be performed at a different channel from the channel on which the TXOP acquired by STA 1 (103) is set. STA 1 (103) cannot communicate with AP 1 (101) while performing Non-802.11 wireless communication and wireless LAN direct communication. Accordingly, STA 1 (103) may want to allow communication nodes including AP 1 (101) and STA 2 (105) to use communication resources while performing Non-802.11 wireless communication and wireless LAN direct communication. Accordingly, STA 1 (103) may include TXOP Termination information in the MAC header of the MPDU or A-MPDU included in the second data frame (402). The TXOP termination information may have a structure identical to or similar to that illustrated in FIG. 9, for example. As another example, the TXOP termination information may be included in the HT Control field of the MAC header in the form of an A-Control. Alternatively, the TXOP termination information may be included in the frame and transmitted in a form other than the A-Control form (e.g., information element, bit, field, or subfield). The TXOP termination information is information indicating that STA 1 (103) terminates the TXOP. STA 1 (103) may indicate the expected transmission time of the BA frame (404) of AP 1 (101) in the duration field of the MAC header, and may include the length of time during which wireless LAN communication is unavailable in the TXOP transmission information. Alternatively, STA 1 (103) may indicate the remaining length of the original TXOP in the duration field of the MAC header, and may include the length of time during which wireless LAN communication is unavailable in the TXOP transmission information. The second data frame (402), which is the last frame transmitted by STA 1 (103) to terminate the TXOP, may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU).

AP 1 (101) may respond with a first control frame (404) after receiving the second data frame (402) of STA 1 (103). The first control frame (404) may include all reception status information for data frames received before transmission of the first control frame (404). A duration field included in the MAC header of the first control frame (404) may be set to 0. After AP 1 (101) responds with the first control frame (404), AP 1 (101) does not transmit a frame to STA 1 (103) for a time period included in the TXOP termination information indicated by STA 1 (103).

STA 2 (105) can set NAV (network allocation vector, 406) according to the value of the duration field included in the MAC header of the MPDU or/and A-MPDU included in the first data frame (400) of STA 1 (103). If NAV (406) is set, the channel is considered busy by virtual carrier sensing. If the channel is considered busy by virtual carrier sensing, the communication node considers the corresponding channel to be occupied when performing a channel sensing operation. STA 2 (105) can update NAV (406) according to the duration field included in the MAC header of the second data frame (402) transmitted by STA 1 (103) and the first control frame (404) transmitted by AP 1 (101). The updated NAV (updated NAV, 408) may be shorter than the NAV (406) set by the first data frame (400), and STA 2 (105) may access the channel based on the NAV (408) updated by the second data frame (402). Alternatively, the first control frame (404) may be a CF-End frame. Communication nodes (e.g., communication nodes including STA 2 (105)) that receive the CF-End frame may end the NAV. That is, the NAV is updated to end the NAV, and STA 2 (105) may access the channel based on the NAV (408) updated by the first control frame (404).

STA 1 (103) can perform a non-802.11 wireless communication or a wireless LAN direct communication operation during the time period indicated in the second data frame (402). When STA 1 (103) terminates TXOP early, when STA 1 (103) performs a non-802.11 communication or a wireless LAN direct communication operation on a link other than a wireless LAN link (e.g., the link through which the first data frame (400) and the second data frame (402) are transmitted), STA 2 (105) can terminate NAV (406) early on the wireless LAN link. Accordingly, unnecessary channel access delays of STAs other than STA 1 (103) can be reduced.

FIG. 5a illustrates a third embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 5b illustrates a fourth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 5c illustrates a fifth embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIGS. 5a, 5b, and 5c, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may also be referred to as a wireless LAN link. The wireless LAN link on which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of multiple links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate while being linked to an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate while being linked to an upper MLD.

STA 1 (103) can perform a channel access procedure on the link. The channel access procedure can be an EDCA backoff operation per AC. If STA 1 (103) succeeds in the backoff operation (e.g., the AC-specific EDCA backoff counter reaches 0) and the AC-specific EDCAF of STA 1 (103) determines to transmit, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple data frames within the TXOP at predetermined intervals. The predetermined interval may be SIFS or XIFS which is longer or shorter than SIFS. XIFS may be shorter than or equal to PIFS. The data frame may be PPDU, MPDU, or A-MPDU. STA 1 (103) transmits a first data frame (500) and a second data frame (502) to AP on the link. 1(101). The transmission interval of the first data frame (500) and the second data frame (502) may be SIFS or other intervals such as XIFS.

Alternatively, a first control frame (504) of AP 1 (101) may be transmitted between the first data frame (500) and the second data frame (502). The control frame may be, for example, one of a BA frame, a CF-End frame, a CTS frame, and an RTS frame. Whether the first control frame (504) should be transmitted between the data frames or after the last data frame (e.g., the second data frame (502)) is transmitted may be determined in advance through negotiation, or may be indicated by including an indicator in the MAC header included in the first transmitted data frame (e.g., the first data frame (500)).

Before transmitting the second data frame (502), STA 1 (103) can know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) or direct wireless LAN communication will be performed.

Referring to FIG. 5a, STA 1 (103) may include TXOP termination information in the MAC header of the MPDU or A-MPDU included in the second data frame (502). The TXOP termination information may have, for example, a structure identical to or similar to that illustrated in FIG. 9. The TXOP termination information may be included in the HT control field of the MAC header in the form of an A-control. Alternatively, the TXOP termination information may be included in the frame and transmitted in a form other than the A-control form (e.g., an information element, a bit, a field, or a subfield). The TXOP termination information is information indicating that STA 1 (103) terminates the TXOP. STA 1 (103) may indicate the expected transmission time of the first control frame (504) of AP 1 (101) in the duration field of the MAC header. In addition, STA 1 (103) may indicate the length of time during which wireless LAN communication is impossible by including it in the TXOP transmission information. Alternatively, STA 1 (103) may indicate the transmission time of the first control frame (504) and the second control frame (506) of AP 1 (101) in the duration field of the MAC header. In addition, STA 1 (103) may indicate the length of time during which wireless LAN communication is unavailable by including it in the TXOP transmission information. Alternatively, STA 1 (103) may indicate the remaining length of the original TXOP in the duration field of the MAC header. In addition, STA 1 (103) may indicate the length of time during which wireless LAN communication is unavailable by including it in the TXOP transmission information.

The second data frame (502), which is the last data frame transmitted by STA 1 (103) to terminate TXOP, may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU).

After receiving the second data frame (502) of STA 1 (103), AP 1 (101) may respond using the first control frame (504). The first control frame (504) may include all reception status information for data frames received before transmitting the first control frame (504). The duration field included in the MAC header of the first control frame (504) may be set to 0. After AP 1 (101) responds using the first control frame (504), AP 1 (101) does not transmit a frame to STA 1 (103) for a time period included in the TXOP termination information indicated by STA 1 (103). AP 1 (101) may transmit the second control frame (506) after transmitting the first control frame (504). STAs that receive the second control frame (506) can initialize NAV (508), and the TXOP is terminated. The second control frame (506) may be a CF-End frame. Alternatively, the second control frame (506) may be a separate frame that instructs to initialize or shorten NAV other than the CF-End frame.

STA 2 (105) can set NAV (508) according to the value of the duration field included in the MAC header of the MPDU or/and A-MPDU included in the first data frame (500) of STA 1 (103). If NAV (508) is set, the channel is considered busy due to virtual carrier detection. STA 2 (105) can update NAV (508) according to the duration field included in the MAC header of the second data frame (502) transmitted by STA 1 (103) and the first control frame (504) transmitted by AP 1 (101). The updated NAV (510) can be shorter than the NAV (508) set by the first data frame (500), and STA 2 (105) can access the channel based on the updated NAV (510).

STA 1 (103) can perform non-802.11 wireless communication or wireless LAN direct communication operation during the time period indicated in the second data frame (502).

Referring to FIG. 5b, STA 1 (103) may include an expected transmission time of the first control frame (504) and a transmission time of the second control frame (512) of AP 1 (101) in the duration field of the MAC header of the MPDU or A-MPDU included in the second data frame (502). AP 1 (101) may respond to the second data frame (502) of STA 1 (103) with the first control frame (504), and STA 1 (103) may transmit the second control frame (512) after receiving the first control frame (504) of AP 1 (101) to indicate termination of TXOP.

STA 2 (105) can set NAV (508) according to the value of the duration field included in the MAC header of the MPDU and/or A-MPDU included in the first data frame (500) of STA 1 (103). If NAV (508) is set, the channel is considered busy by virtual carrier detection. If the channel is considered busy by virtual carrier detection, the communication node considers the corresponding channel to be occupied when performing a channel detection operation. STA 2 (105) can update NAV (508) according to the duration field included in the MAC header of the second data frame (502) transmitted by STA 1 (103) and the BA frame (504) transmitted by AP 1 (101). STA 2 (105) can update NAV (508) when receiving the second control frame (512) of STA 1 (103), and NAV (508) can be initialized. The second control frame (506) may be a CF-End frame. Alternatively, the second control frame (506) may be a separate frame that instructs to initialize or shorten the NAV other than the CF-End frame. The updated NAV (510) may be shorter than the NAV (508) established by the first data frame (500), and STA 2 (105) may access the channel based on the updated NAV (510).

Referring to FIG. 5c, STA 1 (103) may transmit a second data frame (502) to AP 1 (101), and AP 1 (101) may respond to the second data frame (502) of STA 1 (103) using a first control frame (504). STA 1 (103) may transmit a third control frame (514) after receiving the first control frame (504) of AP 1 (101). The third control frame (514) may be a control frame in which a receiver address (RA) is STA 1 (103) itself. The third control frame (103) may be a CTS frame. The duration field of the MAC header of the third control frame (514) may be set to a time length for protecting non-802.11 communication or wireless LAN direct communication of STA 1 (103). For example, the duration field of the MAC header of the third control frame (514) may be set to the remaining length of the Original TXOP initially acquired by STA 1 (103).

STA 2 (105) can set NAV (508) according to the value of the duration field included in the MAC header of the MPDU or/and A-MPDU included in the first data frame (500) of STA 1 (103). If NAV (508) is set, the channel is considered busy by virtual carrier detection. If the channel is considered busy by virtual carrier detection, the communication node considers the corresponding channel to be occupied when performing a channel detection operation. STA 2 (105) can update NAV (508) according to the duration field included in the MAC header of the second data frame (502) transmitted by STA 1 (103), the first control frame (504) transmitted by AP 1 (101), and the third control frame (514) of STA 1 (103). STA 1 (103) can access the channel based on the updated NAV (510).

When STA 1 (103) terminates TXOP early, when STA 1 (103) performs a non-802.11 communication or a wireless LAN direct communication operation on a link other than a wireless LAN link (e.g., the link on which the first data frame (500) and the second data frame (502) are transmitted), other STAs (e.g., STA 2 (105)) other than STA 1 (103) may terminate NAV (508) early on the wireless LAN link. Accordingly, unnecessary channel access delays of other STAs (e.g., STA 2 (105)) other than STA 1 (103) may be reduced. The wireless LAN link may mean a wireless frequency. The other wireless LAN link may mean a wireless frequency different from the aforementioned wireless frequency.

FIG. 6a illustrates a sixth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 6b illustrates a seventh embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 6c illustrates an eighth embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIGS. 6A, 6B, and 6C, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may also be referred to as a wireless LAN link. The wireless LAN link on which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of the multi-link links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate while being linked to an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate while being linked to an upper MLD.

STA 1 (103) can perform a channel access procedure on the link. The channel access procedure may be an AC-specific EDCA backoff operation. If STA 1 (103) succeeds in the backoff operation (e.g., the AC-specific EDCA backoff counter reaches 0) and the AC-specific EDCAF of STA 1 (103) determines transmission, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple data frames within the TXOP at predetermined intervals. The predetermined interval may be SIFS or XIFS. The length of XIFS may be shorter than or equal to PIFS. The data frame may be a PPDU, an MPDU, or an A-MPDU. STA 1 (103) may transmit a first data frame (600) and a second data frame (602) to AP 1 (101) on the link. The transmission interval of the first data frame (600) and the second data frame (602) may be SIFS or another interval, XIFS. Alternatively, a first control frame of AP 1 (101) may be transmitted between the first data frame (600) and the second data frame (602). Whether the first control frame (604) should be transmitted between the data frames or the first control frame (604) should be transmitted after the last data frame (e.g., the second data frame (602)) is transmitted may be determined in advance through negotiation, and an indicator may be included in the MAC header included in the first data frame (e.g., the first data frame (600)) to be transmitted.

Before transmitting the second data frame (602), STA 1 (103) can know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) or direct wireless LAN communication will be performed.

Referring to FIG. 6a, STA 1 (103) may include TXOP forwarding information in the MAC header of the MPDU or A-MPDU included in the second data frame (602). The TXOP forwarding information may have, for example, a structure identical to or similar to that illustrated in FIG. 9. The TXOP forwarding information may be included in the HT Control field of the MAC header in the form of an A-Control. Alternatively, the TXOP forwarding information may be included in the frame and transmitted in a form other than the A-Control form (e.g., an information element, a bit, a field, or a subfield). The TXOP forwarding information may instruct STA 1 (103) to temporarily forward a TXOP to AP 1 (101). STA 1 (103) may indicate the length of the TXOP to be forwarded in the TXOP forwarding information. STA 1 (103) may set the length of the duration field of the MAC header to the remaining length of the Original TXOP. The second data frame (602), which is the last frame transmitted by STA 1 (103) to convey TXOP, may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU).

AP 1 (101) may respond with a first control frame (604) after receiving the second data frame (602) of STA 1 (103). The first control frame (604) may include all reception status information for data frames received before transmitting the first control frame (604). After AP 1 (101) responds with the first control frame (604), AP 1 (101) may perform communication within a time length included in the TXOP transmission information indicated by STA 1 (103). The time length indicated by STA 1 (103) may be referred to as a Transferred TXOP. AP 1 (101) does not transmit a frame to STA 1 (103) within the Transferred TXOP. AP 1 (101) may act as a holder of the Transferred TXOP, or may perform an operation similar to a TXOP holder. AP 1 (101) may transmit a downlink frame to STA 2 (105). Alternatively, AP 1 (101) may transmit a trigger frame to trigger uplink frame transmission. If AP 1 (101) has no frames to transmit, it may not transmit any frames within the Transferred TXOP. If the NAV (606) is properly set for other STAs except STA 1 (103) by the second data frame (602), frame transmission by STAs except STA 1 (103) within the Transferred TXOP may not be performed. Alternatively, if AP 1 (101) has no frames to transmit, it may transmit a data frame having no information. For example, it may transmit a data frame having no data until the end point of the Transferred TXOP.

STA 1 (103) may perform a non-802.11 wireless communication or a wireless LAN direct communication operation during a time period (i.e., Transferred TXOP) indicated in the second data frame (602). STA 1 (103) may transmit a third data frame (608) to AP 1 (101) on the wireless LAN link after the time period indicated in the second data frame (602). STA 1 (103) may transmit the third data frame (608) immediately after the time period indicated by the second data frame (602) or after a certain frame interval (e.g., SIFS). Alternatively, STA 1 (103) may perform a channel access procedure (e.g., EDCA backoff operation) after the time period indicated by the second data frame (602) to transmit the third data frame (608). If the channel access procedure is successful, STA 1 (103) can transmit a third data frame (608).

Referring to FIG. 6b, the second data frame (602) transmitted by STA 1 (103) may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU). The duration field included in the MAC header of the MPDU or A-MPDU included in the second data frame (602) may indicate the remaining length of the Original TXOP.

AP 1 (101) may respond to the second data frame (602) of STA 1 (103) with a first control frame (604). STA 1 (103) may perform a non-802.11 wireless communication or a wireless LAN direct communication operation after receiving the first control frame (604) of AP 1 (101). If the NAV (606) is properly set for other STAs except STA 1 (103) by the second data frame (602), frame transmission by STAs except STA 1 (103) may not be performed while STA 1 (103) performs a non-802.11 wireless communication or a wireless LAN direct communication operation.

STA 1 (103) may transmit a third data frame (608) to AP 1 (101) on the wireless LAN link after termination of the non-802.11 wireless communication or the wireless LAN direct communication. The third data frame (608) may be transmitted immediately after the time indicated by the second data frame (602) or after a certain frame interval (e.g., SIFS). Alternatively, STA 1 (103) may perform a channel access procedure (e.g., EDCA backoff operation) after the time indicated by the second data frame (602) to transmit the third data frame (608). If the channel access procedure is successful, STA 1 (103) may transmit the third data frame (608).

Referring to FIG. 6c, the second data frame (602) transmitted by STA 1 (103) may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU). The duration field included in the MAC header of the MPDU or A-MPDU included in the second data frame (602) may indicate the remaining length of the Original TXOP.

AP 1 (101) may respond to the second data frame (602) of STA 1 (103) with a first control frame (604). STA 1 (103) may transmit a third control frame (610) after receiving the first control frame (604) of AP 1 (101). The non-802.11 transmission and wireless LAN direct communication of STA 1 (103) may be performed on a wireless LAN link (e.g., the link through which the first data frame (600) and the second data frame (602) are transmitted). That is, the non-802.11 wireless communication or the wireless LAN direct communication may be performed on the same channel as the channel to which the TXOP acquired by STA 1 (103) is set. Therefore, the non-802.11 wireless communication or wireless LAN direct communication of STA 1 (103) needs to be protected, and if a communication node other than STA 1 (103) transmits, the wireless communication or wireless LAN direct communication of STA 1 may be interfered with. The third control frame (610) may be transmitted to protect the non-802.11 transmission and wireless LAN direct communication of STA 1 (103). The third control frame (610) transmitted by STA 1 (103) may be a control frame whose receiver address is STA 1 (103) itself. As an example of the third control frame (610), the third control frame (610) may be a CTS frame. The duration field included in the MAC header of the third control frame (610) may indicate the remaining time interval of the Original TXOP. After transmission of the third control frame (610), STA 1 (103) may perform non-802.11 wireless communication or wireless LAN direct communication operation. If NAV (606) is properly set for other STAs except STA 1 (103) by the second data frame (602) and the third control frame (610), frame transmission by STAs except STA 1 (103) may not be performed while STA 1 (103) performs non-802.11 wireless communication or wireless LAN direct communication operation.

STA 1 (103) may transmit a third data frame (608) to AP 1 (101) on the wireless LAN link after termination of the non-802.11 wireless communication or the wireless LAN direct communication. The third data frame (608) may be transmitted immediately after the time indicated by the second data frame (602), or after a certain time interval (e.g., SIFS). Alternatively, STA 1 (103) may perform a channel access procedure (e.g., EDCA backoff operation) after the time indicated by the second data frame (602) to transmit the third data frame (608). If the channel access procedure is successful, STA 1 (103) may transmit the third data frame (608).

FIG. 7a illustrates a ninth embodiment of a communication method when interference occurs in a wireless LAN system.

FIG. 7b illustrates a tenth embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIGS. 7A and 7B, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may also be referred to as a wireless LAN link. The wireless LAN link on which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of multiple links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate in conjunction with an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate in conjunction with an upper MLD.

STA 1 (103) can perform a channel access procedure on the link. The channel access procedure may be an AC-specific EDCA backoff operation. If STA 1 (103) succeeds in the backoff operation (e.g., the AC-specific EDCA backoff counter reaches 0) and the AC-specific EDCAF of STA 1 (103) determines transmission, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple data frames within the TXOP at predetermined intervals. The predetermined interval may be SIFS or XIFS which is longer or shorter than SIFS. XIFS may be shorter than or equal to PIFS. The data frame may be a PPDU, MPDU, or A-MPDU. STA 1 (103) may transmit a first data frame (700) and a second data frame (702) to AP 1 (101) on the link. The transmission interval of the first data frame (700) and the second data frame (702) may be SIFS or another interval, XIFS. Alternatively, a first control frame (704) of AP 1 (101) may be transmitted between the first data frame (700) and the second data frame (702). Whether the first control frame (704) should be transmitted between the data frames or after the transmission of the last data frame (e.g., the second data frame (702)) may be determined in advance through negotiation, or may be indicated by including an indicator in the MAC header included in the first transmitted data frame (e.g., the first data frame (700)).

Before transmitting the second data frame (702), STA 1 (103) can know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) or direct wireless LAN communication will be performed.

Referring to FIG. 7a, the MAC header of the MPDU or A-MPDU included in the second data frame (702) may include TXOP forwarding information. The TXOP forwarding information may have, for example, a structure identical to or similar to that illustrated in FIG. 9. The TXOP forwarding information may be included in the HT Control field of the MAC header in the form of an A-Control. Alternatively, the TXOP forwarding information may be included in a frame and transmitted in a form other than the A-Control form (e.g., an information element, a bit, a field, or a subfield). The TXOP forwarding information may instruct STA 1 (103) to temporarily forward a TXOP to AP 1 (101). STA 1 (103) may indicate the length of the TXOP to be forwarded in the TXOP forwarding information. STA 1 (103) may set the length of the duration field of the MAC header to the remaining length of the Original TXOP. The TXOP transmission information further includes information that STA 1 (103) requests a trigger frame (706) from AP 1 (101). The transmission time of the trigger frame (706) that STA 1 (103) requests from AP 1 (101) may be after the time length included in the TXOP transmission information indicated by STA 1 (103). The second data frame (702), which is the last frame that STA 1 (103) transmits to transmit the TXOP, may be transmitted in a format that legacy terminals can recognize (e.g., non-HT PPDU).

AP 1 (101) may respond with a first control frame (704) after receiving the second data frame (702) of STA 1 (103). The first control frame (704) may include all reception status information for data frames received before transmitting the first control frame (704). After AP 1 (101) responds with the first control frame (704), AP 1 (101) may perform communication within a time length included in the TXOP transmission information indicated by STA 1 (103). The time length indicated by STA 1 (103) may be referred to as Transferred TXOP. AP 1 (101) does not transmit frames to STA 1 (103) within the Transferred TXOP. AP 1 (101) may act as a holder of the Transferred TXOP or may perform an operation similar to a TXOP holder. AP 1 (101) may transmit a downlink frame to STA 2 (105). Alternatively, AP 1 (101) may transmit a trigger frame (706) to trigger uplink frame transmission. If AP 1 (101) has no frame to transmit, it may not transmit any frame within the Transferred TXOP. If NAVs are correctly set for STAs other than STA 1 (103) by the second data frame (702), frame transmission by STAs other than STA 1 (103) within the Transferred TXOP may not be performed.

STA 1 (103) may perform a non-802.11 wireless communication or wireless LAN direct communication operation during the time period indicated in the second data frame (702). The non-802.11 wireless communication or wireless LAN direct communication operation performed by STA 1 (103) may have been performed at a frequency (or link) different from the operating frequency at which the first data frame (700) and the second data frame (702) were transmitted. Since STA 1 (103) did not detect a wireless LAN channel for a certain period of time, it is considered that medium synchronization was lost. STA 1 (103) sets a MediumSyncDelay timer after the non-802.11 wireless communication or wireless LAN direct communication operation is completed in order to recover medium synchronization. While the MediumSyncDelay timer is operating, STA 1 (103) may perform channel detection and frame reception operations and may not transmit frames. The MediumSyncDelay timer can be initialized when a correct frame (e.g., MPDU or A-MPDU) is received and NAV is set. The length of the MediumSyncDelay timer can be a preset value (e.g., aPPDUMaxTime, which is the length of the maximum PPDU). AP 1 (101) can transmit a trigger frame (706) to STA 1 (103). STA 1 (103) can initialize the MediumSyncDelay timer based on the trigger frame (706) and transmit an uplink frame. STA 1 (103) can transmit a third data frame to AP 1 (101) after receiving the trigger frame (706) of AP 1 (101).

Referring to FIG. 7b, STA 1 (103) may include information requesting a trigger frame (706) in the MAC header of the MPDU or A-MPDU included in the second data frame (702). The information requesting the trigger frame (706) includes information that STA 1 (103) requests the trigger frame (706) from AP 1 (101). The information requesting the trigger frame (706) may have, for example, a structure identical to or similar to that illustrated in FIG. 9. Alternatively, the information requesting the trigger frame (706) may be included in a format identical to or similar to an AAR (Assisted AP Request) A-control format. The information requesting the trigger frame (706) may be included in the HT control field of the MAC header in the form of an A-control. Alternatively, the information requesting the trigger frame (706) may be included in a frame and transmitted in a form other than the A-control form (e.g., an information element, a bit, a field, or a subfield). The transmission time of the trigger frame (706) that STA 1 (103) requests AP 1 (101) may be after the time length included in the information requesting the trigger frame (706) indicated by STA 1 (103). The last data frame (e.g., the second data frame (702)) that STA 1 (103) transmits to convey TXOP may be transmitted in a format that legacy terminals can recognize (e.g., non-HT PPDU).

If NAVs are correctly set for STAs other than STA 1 (103) by the second data frame (702), frame transmission by STAs other than STA 1 (103) within the Transferred TXOP may not be performed.

STA 1 (103) may perform a non-802.11 wireless communication or wireless LAN direct communication operation during the time period indicated in the second data frame (702). The non-802.11 wireless communication or wireless LAN direct communication operation performed by STA 1 (103) may have been performed at a frequency (or link) different from the operating frequency at which the first data frame (700) and the second data frame (702) were transmitted. Since STA 1 (103) did not detect a wireless LAN channel for a certain period of time, it is considered that medium synchronization was lost. STA 1 (103) sets a MediumSyncDelay timer after the non-802.11 wireless communication or wireless LAN direct communication operation is completed in order to recover medium synchronization. STA 1 (103) may perform channel detection and frame reception operations while the MediumSyncDelay timer is operating, and may not transmit frames. The MediumSyncDelay timer may be initialized when a correct data frame (e.g., MPDU, A-MPDU) is received. The length of the MediumSyncDelay timer may be a preset value (e.g., aPPDUMaxTime, which is the length of the maximum PPDU). AP 1 (101) may transmit a trigger frame (706) to STA 1 (103). STA 1 (103) may initialize the MediumSyncDelay timer and transmit an uplink frame based on the trigger frame (706). STA 1 (103) may transmit a third data frame to AP 1 (101) after receiving the trigger frame (706) of AP 1 (101).

Figure 8 illustrates an eleventh embodiment of a communication method when interference occurs in a wireless LAN system.

Referring to FIG. 8, AP 1 (101), STA 1 (103), and STA 2 (105) may operate in a wireless LAN channel. The wireless LAN channel may be referred to as a wireless LAN link. The wireless LAN link on which AP 1 (101), STA 1 (103), and STA 2 (105) operate may be one of multiple links. That is, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may operate in conjunction with an upper MLD. Alternatively, at least one terminal among AP 1 (101), STA 1 (103), and STA 2 (105) may not operate in conjunction with an upper MLD.

STA 1 (103) can perform a channel access procedure on the link. The channel access procedure may be an AC-specific EDCA backoff operation. If STA 1 (103) succeeds in the backoff operation (e.g., the AC-specific EDCA backoff counter reaches 0) and the AC-specific EDCAF of STA 1 (103) determines transmission, STA 1 (103) is considered to have acquired a TXOP. That is, STA 1 (103) is a TXOP holder. STA 1 (103), which is a TXOP holder, may have acquired a TXOP equal to the length of the Original TXOP. STA 1 (103) may transmit multiple frames within the TXOP at predetermined intervals. The predetermined interval may be SIFS or XIFS which is longer or shorter than SIFS. XIFS is shorter than or equal to PIFS. A data frame may be a PPDU, MPDU, or A-MPDU. STA 1 (103) may transmit a first data frame (800) and a second data frame (802) to AP 1 (101) on the link. The transmission interval of the first data frame (800) and the second data frame (802) may be SIFS or another interval, XIFS. Alternatively, a first control frame (804) of AP 1 (101) may be transmitted between the first data frame (800) and the second data frame (802). Whether the first control frame (804) should be transmitted between the data frames or after the transmission of the last data frame (e.g., the second data frame (802)) may be determined in advance through negotiation, or may be indicated by an indicator included in the MAC header included in the first transmitted data frame (e.g., the first data frame (800)).

Before transmitting the second data frame (802), STA 1 (103) may know that non-802.11 wireless communication (e.g., Bluetooth communication, cellular communication, etc.) is to be performed, or that wireless LAN direct communication is to be performed. The non-802.11 wireless communication or wireless LAN direct communication operation of STA 1 (103) may be performed on the same channel (or link) as the wireless LAN link through which the first data frame (800) and the second data frame (802) are transmitted. If the non-802.11 wireless communication or wireless LAN direct communication operation of STA 1 (103) is performed on the same channel (or link) as the wireless LAN link through which the first data frame (800) and the second data frame (802) are transmitted, STA 1 (103) cannot perform the non-802.11 wireless communication or wireless LAN direct communication operation in a range exceeding the acquired Original TXOP. If STA 1 (103) performs communication operations within a range that does not exceed the Original TXOP, fairness of other STAs except STA 1 (103) can be guaranteed.

Figure 9 shows an example of A-control information.

Referring to FIG. 9, A-control information (900) may indicate at least one of the TXOP forwarding information, TXOP termination information, and information requesting a trigger frame described in FIGS. 3 to 8. The information illustrated in FIG. 9 is A-control information (900) included in the HT control field included in the MAC header. Alternatively, the information illustrated in FIG. 9 may be information included in a frame in the form of an information element, a field, or a subfield.

A-control information (900) may be transmitted by being included in a frame in which an HT control field exists in the MAC header of a data frame (e.g., MPDU or A-MPDU). A-control information (900) may be a variant of the HT control field or the HT control field format. The HT control field may include control information of wireless LAN terminals. Accordingly, A-control information (900), which is a variant of the HT control field, may include control information of wireless LAN terminals.

The Control ID subfield (902) is a bit for distinguishing A-control information (900).

The TXOP forwarding subfield (904) is a 2-bit subfield for distinguishing a TXOP transmission operation. When the TXOP forwarding subfield (904) is set to 00, the STA or AP that has received the information does not perform any operation. When the TXOP forwarding subfield (904) is set to 01, the STA or AP that has received the information receives the TXOP. The length of the received TXOP may be the length indicated in the Interruption Duration subfield (906) of the information illustrated in FIG. 9, or the length of the Duration field included in the MAC header of the frame in which the information illustrated in FIG. 9 is transmitted. When the TXOP forwarding subfield (904) is set to 10, the STA or AP that has received the information may temporarily receive the TXOP for the time length included in the information (e.g., the length indicated in the Interruption Duration subfield (906)). When the TXOP forwarding subfield (904) is set to 11, it may indicate the end of TXOP.

The Interruption Duration subfield (906) indicates how long the STA transmitting the information illustrated in FIG. 9 performs a non-802.11 communication operation or a wireless LAN direct communication operation. The Interruption Duration subfield (906) indicates the length of time and is interpreted in the same or similar manner as the Duration field included in the MAC header.

The Link ID subfield (908) can indicate the link where interference occurs.

The TF request subfield (910) is a field that requests a trigger frame (e.g., 706 of FIG. 7a) to be transmitted to an STA or AP receiving the information illustrated in FIG. 9. If the bit of the TF request subfield (910) is 0, a trigger frame (e.g., 706 of FIG. 7a) is not requested. If the bit of the TF request subfield (910) is 1, a trigger frame (e.g., 706 of FIG. 7a) is requested.

In the embodiment described with reference to FIGS. 3 to 8, at least one of TXOP forwarding, TXOP termination, and TF request may be indicated by at least one of information from among the TXOP forwarding subfield (904), the Interruption Duration subfield (906), the Link ID subfield (908), and the TF Request subfield (910). The length and form of each subfield may be changed or modified.

FIG. 10 illustrates an operation flow diagram of an AP according to one embodiment of the present disclosure. FIG. 10 illustrates an operation method of an AP (e.g., AP 1 (101) of FIG. 5A).

Referring to FIG. 10, in step S1001, the AP receives at least one data frame from a first STA (e.g., STA 1 (103) of FIG. 5a). The at least one data frame may be, for example, one of a PPDU, an MPDU, or an A-MPDU. One of the at least one data frame may include information related to transmission of one of the at least one control frame (e.g., the first control frame (504) of FIG. 5a) and one of information related to TXOP.

In step S1003, the AP transmits at least one control frame. The control frame may be, for example, one of a BA frame, a CF-End frame, an RTS frame, a CTS frame, and an ACK frame. When the AP transmits multiple control frames, each control frame may be transmitted at a different time. For example, the AP may transmit at least one control frame each time it receives one data frame from the first STA. As another example, the AP may transmit at least one control frame after receiving the last data frame from the first STA before the non-802.11 wireless communication or the wireless LAN direct communication of the first STA. The time at which the control frame is transmitted may be indicated by the first STA. Alternatively, the time at which the control frame is transmitted may be determined in advance through negotiation between the first STA and the AP. The AP may determine the number or type of control frames to be transmitted based on information related to the TXOP.

In step S1005, the AP performs an operation related to the TXOP of the first STA. The operation related to the TXOP of the first STA may include an operation of terminating the TXOP of the first STA or receiving the TXOP of the first STA. For example, if the information related to the TXOP includes TXOP termination information, the AP terminates the TXOP of the first STA by transmitting a control frame including CF-End. As another example, if the information related to the TXOP includes TXOP transfer information, the AP receives the TXOP from the first STA. Here, the transfer of the TXOP includes an operation of the AP acquiring a TXOP having a length equal to the remaining time of the first STA and an operation of the first STA terminating the TXOP. The AP that has received the TXOP may operate as a temporary TXOP holder. The AP, which is a temporary TXOP holder, may transmit a data frame and a trigger frame to other STAs other than the first STA.

FIG. 11 is a flowchart illustrating an operation of a first STA according to an embodiment of the present disclosure. FIG. 11 illustrates an operation method of a first STA (e.g., STA 1 (103) of FIG. 5A). The first STA according to an embodiment of the present disclosure may be an STA that performs non-802.11 wireless communication or wireless LAN direct communication from time point 1. For example, the first STA may receive information related to non-802.11 wireless communication or wireless LAN direct communication by using an input interface device.

Referring to FIG. 11, in step S1101, the first STA performs a channel access procedure. If the channel access procedure is successful, the first STA obtains a TXOP. The channel access procedure may be, for example, an AC-specific EDCA backoff operation. According to one embodiment of the present disclosure, if the first STA succeeds in the backoff operation and the AC-specific EDCAF of the first STA determines transmission, the first STA obtains a TXOP. The success of the backoff operation may mean, for example, that the AC-specific EDCA backoff counter reaches 0. The length of the TXOP may be, for example, a time length as long as the original TXOP.

In step S1103, the first STA transmits at least one data frame at a predetermined time interval. The data frame(s) transmitted by the first STA may be, for example, a PPDU, an MPDU, or an A-MPDU. Here, the predetermined time interval may be, for example, an SIFS. As another example, the predetermined time interval may be a time interval shorter than or equal to a PIFS. One of the at least one data frame transmitted by the first STA may include information related to a TXOP. The information related to the TXOP includes at least one of TXOP termination information and TXOP forwarding information. The information related to the TXOP may be included in the HT control field of the MAC header in the form of an A-control (900), for example. Alternatively, the information related to the TXOP may be included in the frame in a form other than the A-control form (for example, an information element, a bit, a field, or a subfield). The information related to the TXOP may be, for example, information indicated using the TXOP forwarding subfield (904) illustrated in FIG. 9. The last frame in time among the transmitted frames (e.g., the second data frame (502) of FIG. 5a) may be transmitted in a format recognizable by legacy terminals (e.g., non-HT PPDU).

In step S1105, the first STA receives at least one control frame. The at least one control frame may include, for example, at least one of a BA frame, a CF-End frame, an RTS frame, a CTS frame, and an ACK frame.

In step S1107, the first STA performs an exclusive operation with respect to wireless LAN communication. Here, the exclusive operation with respect to wireless LAN communication may be referred to as an operation that is incompatible with the wireless LAN system, or an operation that causes interference with wireless LAN communication. The exclusive operation with respect to wireless LAN communication may be, for example, at least one of an operation of terminating a TXOP, an operation of transferring a TXOP, and an operation of performing non-802.11 wireless communication or wireless LAN direct communication. The operation of performing non-802.11 wireless communication or wireless LAN direct communication may cause interference with the wireless LAN communication. The first STA may perform the exclusive operation with respect to wireless LAN communication based on information related to the TXOP. The non-802.11 wireless communication may include, for example, Bluetooth communication. The non-802.11 wireless communication or wireless LAN direct communication may be performed using the same frequency as or a different frequency from the 802.11 wireless communication.

FIG. 12 illustrates an operation flow diagram of a second STA according to one embodiment of the present disclosure.

Referring to FIG. 12, in step S1201, a second STA (e.g., STA 2 (105) of FIG. 5a) receives one of the data frames transmitted by a first STA (e.g., STA 1 (103) of FIG. 5a). The second STA sets a NAV (e.g., NAV (508) of FIG. 5a) based on the received data frame. For example, the second STA sets the NAV according to the value of the duration field included in the received data frame. When the NAV is set, the channel of the second STA is considered busy by virtual carrier detection. When the channel is considered busy by virtual carrier detection, the communication node considers the corresponding channel to be occupied when performing a channel detection operation. In other words, the second STA cannot transmit a frame to an AP (e.g., AP 1 (101) of FIG. 5a).

In step S1203, the second STA updates the NAV based on at least one of the received control frame and data frame. The control frame is transmitted from the AP. The data frame is transmitted from the first STA. For example, the second STA updates the NAV according to a duration field included in at least one of the received frames. The updated NAV (e.g., the updated NAV (510) of FIG. 5A) may have a shorter temporal length than the NAV before being updated. Alternatively, the second STA may initialize the NAV if it receives a control frame including CF-End (e.g., the second control frame (506) of FIG. 5A).

The methods according to the present invention may be implemented in the form of program commands that can be executed through various computer means and recorded on a computer-readable medium. The computer-readable medium may include program commands, data files, data structures, etc., alone or in combination. The program commands recorded on the computer-readable medium may be those specially designed and configured for the present invention or may be those known and available to those skilled in the art of computer software.

Examples of computer-readable media include hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include not only machine language codes generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The above-described hardware devices can be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Although the present invention has been described with reference to the above embodiments, it will be understood by those skilled in the art that various modifications and changes can be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.

The present invention can be used in devices and recording media of a wireless LAN system.

Claims (19)

In the operation method of an AP (access point) in a wireless LAN system, A step of receiving at least one data frame from a first STA (first station); A step of transmitting at least one control frame to at least one STA (station) including the first STA; and A step of performing an operation related to a TXOP (transmit opportunity) of the first STA is included. A method wherein one of the at least one data frame includes information related to a TXOP of the first STA. In claim 1, A method wherein the information related to the TXOP includes at least one of information indicating termination of the TXOP and information indicating transmission of the TXOP. In claim 2, The information related to the above TXOP includes information indicating the termination of the above TXOP, The above TXOP-related operation comprises a method including transmission of a CF-End (contention free-end) frame. In claim 2, The information related to the above TXOP includes information indicating transmission of the above TXOP, The steps for performing the above TXOP-related operations are: A step of obtaining a remaining TXOP equal to the remaining time of the TXOP from the first STA; and A method comprising the step of acting as a holder of the remaining TXOP. In claim 4, The step of acting as the holder of the above remaining TXOP is: A method comprising the step of transmitting at least one of a trigger frame and a data frame to at least one STA excluding the first STA. In claim 4, The step of acting as the holder of the above remaining TXOP is: A method comprising the step of terminating the remaining TXOP. In claim 1, A method wherein the at least one control frame comprises at least one of a BA (block ack) frame, a CTS (clear to send) frame, and a CF-End frame. In claim 1, A method wherein at least one of said at least one data frame includes information regarding a transmission time of said control frame. In claim 1, A method in which the information related to the above TXOP includes at least one of information related to a time when the first STA cannot perform wireless LAN communication and information requesting a trigger frame. In claim 1, A method wherein at least one data frame is received at predefined time intervals. In claim 10, The above predefined time interval is shorter than PIFS (PCF inter-frame space). In a method of operation of a first STA (first station) in a wireless LAN system, Step for obtaining TXOP (transmit opportunity); A step of transmitting at least one data frame to an AP (access point); A step of receiving at least one control frame from the AP; and Including steps for performing wireless LAN communication and exclusive operations, A method wherein one of said at least one data frame includes information related to said TXOP. In Article 12, A method wherein the information related to the TXOP includes at least one of information indicating termination of the TXOP and information indicating transmission of the TXOP. In claim 13, A method for exclusive operation of the above wireless LAN communication, comprising terminating the TXOP. In claim 13, A method wherein the above wireless LAN communication and exclusive operation include an operation that causes interference with the above wireless LAN communication. In claim 12, The above one frame is transmitted in a format that legacy terminals can recognize. In claim 12, At least one of said data frames is transmitted at predefined time intervals, The above predefined time interval is shorter than PIFS (PCF inter-frame space). In a wireless LAN system, in a communication node, Transmitter and receiver; and comprising a processor connected to the transceiver; The above transceiver receives at least one data frame from the first STA, The transceiver transmits at least one control frame to at least one STA (station) including the first STA, The above processor performs an operation related to a TXOP (transmit opportunity) of the first STA, A communication node, wherein one of said at least one data frame includes information related to a TXOP of said first STA. In a wireless LAN system, in a communication node, Transmitter and receiver; and comprising a processor connected to the transceiver; The above processor acquires a TXOP (transmit opportunity), The above transceiver transmits at least one data frame to an AP (access point), The transceiver receives at least one control frame from the AP, The above processor performs wireless LAN communication and exclusive operations, A communication node, wherein one of said at least one data frame includes information related to said TXOP.

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