KR20230071028A - Device and method for wireless communication using multi-link - Google Patents

Abstract

A wireless communication method of a first device with a second device using a plurality of links including first and second links according to an aspect of the technical idea of the present disclosure includes a first RTS (request request) through the first link. to send) frame transmission preparation period, obtaining transmission related information of the second RTS frame through the second link, based on the transmission related information, the additional length of the first RTS frame and the cross- Determining at least one of link related information and determining whether to transmit the second RTS frame based on a result of the determination.

Description

Apparatus and method for wireless communication using multi-link {DEVICE AND METHOD FOR WIRELESS COMMUNICATION USING MULTI-LINK}

The technical spirit of the present disclosure relates to wireless communication, and more specifically, to an apparatus and method for wireless communication using multi-link.

As an example of wireless communication, a wireless local area network (WLAN) is a technology for connecting two or more devices to each other using a wireless signal transmission method. The WLAN technology may be based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. The 802.11 standard has evolved into 802.11b, 802.11a, 802.11g, 802.11n, 802.11ac and 802.11ax, and based on orthogonal frequency-division multiplexing (OFDM) technology, transmission rates of up to 1 Gbyte/s are achieved. can support

In 802.11ac, data can be simultaneously transmitted to multiple users through a multi-user multi-input multi-output (MU-MIMO) scheme. In 802.11ax, which is referred to as high efficiency (HE), not only MU-MIMO but also orthogonal frequency-division multiple access (OFDMA) technology is applied to provide multiple access by dividing and providing available subcarriers to users. are implementing Through this, a WLAN system to which 802.11ax is applied can effectively support communication in densely populated areas and outdoors.

In 802.11be, which is referred to as EHT (extremely high throughput), support for a 6GHz unlicensed frequency band, utilization of up to 320MHz of bandwidth per channel, introduction of hybrid automatic repeat and request (HARQ), and support for up to 16X16 MIMO are intended to be implemented. Through this, the next-generation WLAN system is expected to effectively support low latency and high-speed transmission like NR (new radio), a 5G technology.

An object to be solved by the technical idea of the present disclosure is to provide an apparatus and method for improving data reliability in wireless communication using multi-link.

In order to achieve the above object, a wireless communication method of a first device with a second device using a plurality of links including first and second links includes a first RTS (request to send) entering a transmission preparation period of a frame, obtaining transmission-related information of a second RTS frame through the second link, additional length of the first RTS frame and cross-link based on the transmission-related information Determining at least one of related information and determining whether to transmit the second RTS frame based on a result of the determination.

According to another aspect of the technical idea of the present disclosure, a first device configured to communicate with a second device using a plurality of links including first and second links includes an access point corresponding to the first and second links, respectively. A radio frequency (RF) integrated circuit configured to provide a radio frequency (RF) integrated circuit and a processor configured to control the RF integrated circuit, wherein the processor, in a transmission preparation period of a first RTS frame through the first link, through a second link Obtain transmission related information of the second RTS frame, determine at least one of an additional length of the first RTS frame and cross-link related information based on the transmission related information, and determine the second RTS based on the determination result It is characterized in that it is configured to determine whether to transmit the frame.

According to another aspect of the technical idea of the present disclosure, a first device configured to communicate with a second device using a plurality of links including first and second links includes access corresponding to the first and second links, respectively. A radio frequency (RF) integrated circuit configured to provide points and a processor configured to control the RF integrated circuit, wherein the processor operates a second link in a preparation period for transmission of a first RTS frame through the first link. obtaining transmission-related information of a second RTS frame through transmission-related information, determining at least one of an additional length of the first RTS frame and cross-link related information based on the transmission-related information, and determining the second RTS frame based on the determination result. It is characterized in that it is configured to determine whether to transmit the RTS frame.

When RTS frames and CTS frames are transmitted and received using multi-links, interference between adjacent links can be avoided by the apparatus and method according to exemplary embodiments of the present disclosure. Accordingly, the signaling of the protection mechanism using the multi-link is smoothly performed by the apparatus and method, thereby ensuring reliability of data communication.

In addition, the format of the RTS frame used in the apparatus and method according to the exemplary embodiment of the present disclosure is among a plurality of trigger formats defined in the standard specification so that padding data or cross-link related information can be properly disposed. Any one of them may be adopted or newly defined to support signaling of an efficient protection mechanism.

Effects obtainable in the exemplary embodiments of the present disclosure are not limited to the effects mentioned above, and other effects not mentioned are common knowledge in the art to which exemplary embodiments of the present disclosure belong from the following description. can be clearly derived and understood by those who have That is, unintended effects according to the implementation of the exemplary embodiments of the present disclosure may also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

1 is a diagram illustrating a wireless communication system according to an exemplary embodiment of the present disclosure.
2 is a block diagram illustrating a wireless communication system according to an exemplary embodiment of the present disclosure.
3 is a block diagram illustrating a wireless communication system according to an exemplary embodiment of the present disclosure.
4A and 4B are timing diagrams illustrating examples of multi-link operation.
5 is a timing diagram including signaling based on a protection mechanism in multi-link operation.
6A and 6B are flowcharts illustrating a method of operating an AP MLD according to an exemplary embodiment of the present disclosure.
7 is a timing diagram illustrating an example of multi-link operation according to an exemplary embodiment of the present disclosure.
8A and 8B are flowcharts illustrating a method of operating an AP MLD according to an exemplary embodiment of the present disclosure.
9 is a table diagram for explaining cross-link related information according to an exemplary embodiment of the present disclosure.
10A and 10B are flowcharts illustrating an operation method of an AP MLD and a non-AP MLD according to exemplary embodiments of the present disclosure.
11 is a table diagram for explaining cross-link related information according to an exemplary embodiment of the present disclosure.
FIG. 12 is a flowchart illustrating a specific embodiment of step S330 of FIG. 10A using the cross-link related information of FIG. 11 .
13A-13C are timing diagrams illustrating examples of multi-link operation according to example embodiments of the present disclosure.
14A and 14B are diagrams illustrating formats of RTS frames according to exemplary embodiments of the present disclosure.
15 is a diagram for explaining an embodiment in which cross-link related information is arranged in a format of a trigger frame according to an exemplary embodiment of the present disclosure.
FIG. 16 is a diagram for explaining trigger frame formats adoptable to an RTS frame format according to an exemplary embodiment of the present disclosure.
17 and 18 are diagrams for explaining RTS frames employing the 'MU-RTS' format according to exemplary embodiments of the present disclosure.
19 is a block diagram illustrating a system according to an exemplary embodiment of the present disclosure.
20 is a diagram illustrating examples of an apparatus for wireless communication according to an exemplary embodiment of the present disclosure.

1 is a diagram illustrating a wireless communication system 10 according to an exemplary embodiment of the present disclosure. Specifically, FIG. 1 shows a wireless local area network (WLAN) system as an example of a wireless communication system 10 .

Hereinafter, embodiments of the present disclosure are described based on an OFDM or OFDMA-based wireless communication system, in particular, based on the IEEE 802.11 standard, but the main gist of the present disclosure is other communication systems having a similar technical background and channel type (eg For example, a cellular communication system such as long term evolution (LTE), LTE-advanced (LTE-A), new radio (NR), wireless broadband (WiBro), global system for mobile communication (GSM) or Bluetooth ), a short-range communication system such as near field communication (NFC)) may also be applied with slight modifications within a range that does not greatly deviate from the scope of the present disclosure.

In addition, various functions described below may be implemented or supported by artificial intelligence technology or one or more computer programs, each of which is composed of computer readable program code and implemented in a computer readable medium. do. The terms "application" and "program" refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or portions thereof suitable for implementation in suitable computer readable program code. The term "computer readable program code" includes all types of computer code, including source code, object code, and executable code. The term "computer readable medium" means a computer memory, such as read only memory (ROM), random access memory (RAM), hard disk drive, compact disc (CD), digital video disc (DVD), or any other type of memory. Includes all types of media that can be accessed by A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transmit transitory electrical or other signals. Non-transitory computer readable media include media on which data can be permanently stored, and media on which data can be stored and later overwritten, such as rewritable optical discs or removable memory devices.

In various embodiments of the present disclosure described below, a hardware access method will be described as an example. However, since various embodiments of the present disclosure include technology using both hardware and software, various embodiments of the present disclosure do not exclude software-based access methods.

Referring to FIG. 1 , the wireless communication system 10 may include first to sixth devices D1_1, D1_2, D2_1, D2_2, D2_3, and D2_4. The first and second devices D1_1 and D1_2 may access a network 13 including the Internet, an internet protocol (IP) network, or any other network. The first device D1_1 may access the network 13 within the first coverage area 11 . The first device D1_1 may provide access to the network 13 within the first coverage area 11 to the third to sixth devices D2_1, D2_2, D2_3, and D2_4, and the second device D1_2 ) may provide access to the network 13 within the second coverage area 12 to the third and fourth devices D2_1 and D2_2.

In example embodiments, the first and second devices D1_1 and D1_2 are among the third to sixth devices D2_1, D2_2, D2_3, and D2_4 based on wireless fidelity (WiFi) or any other WLAN access technology. It can communicate with at least one using multi-link. The first and second devices D1_1 and D1_2 may correspond to access point multi-link devices (hereinafter referred to as AP MLD), and the third to sixth devices D2_1, D2_2 and D2_3 , D2_4) may correspond to a non-access point multi-link device (hereinafter referred to as non-AP MLD). In the present specification, an AP MLD is a device capable of supporting a plurality of access points (hereinafter referred to as APs), and a non-AP MLD is a plurality of stations (hereinafter referred to as STAs). Can support It is a device that has

In some embodiments, the first and second devices D1_1 and D1_2 may be referred to as a router, a gateway, a router, and the like, and the third to sixth devices D2_1, D2_2, D2_3, D2_4) may be referred to as a terminal, mobile terminal, wireless terminal, user equipment, and the like. In addition, the third to sixth devices D2_1, D2_2, D2_3, and D2_4 may be mobile devices such as mobile phones, laptop computers, and wearable devices, or may be stationary devices such as desktop computers and smart TVs. .

The AP MLD may allocate at least one resource unit (RU) to at least one non-AP MLD. The AP MLD may transmit data through at least one allocated resource unit, and the non-AP MLD may receive the data through at least one allocated resource unit. In 802.11be (hereinafter referred to as EHT) or next-generation IEEE 802.11 standards (hereinafter referred to as EHT+), an AP MLD may allocate a multi-resource unit (MRU) including two or more resource units to at least one non-AP MLD. can For example, the first device D1_1 may allocate multiple resource units to at least one of the third to sixth devices D2_1, D2_2, D2_3, and D2_4, and transmit data through the allocated multiple resource units. there is.

As an exemplary embodiment, when the AP MLD and the non-AP MLD perform communication through multi-links, a protection mechanism for guaranteeing reliability of data communication may be selectively activated for each link. For example, in communication between an AP MLD and a non-AP MLD, a protection mechanism may be activated in communication through a first link, and a protection mechanism may be deactivated in communication through a second link. The AP MLD may adaptively control at least one of the transmission timing of an arbitrary frame and the contents of an arbitrary frame so that signaling defined in the protection mechanism can be effectively performed with the non-AP MLD. In some embodiments, the non-AP MLD may also adaptively control at least one of the transmission timing of an arbitrary frame and the contents of an arbitrary frame so that the signaling defined in the protection mechanism can be effectively performed with the AP MLD. Hereinafter, for convenience of description, embodiments are described centering on the operation of the AP MLD, but this is only an exemplary embodiment and is not limited thereto, and exemplary embodiments of the present disclosure may be applied to non-AP MLD as well. there is.

Hereinafter, for convenience of description, embodiments are described centering on the operation of the AP MLD, but this is only an exemplary embodiment and is not limited thereto, and the exemplary embodiments of the present disclosure are sufficiently applicable to non-AP MLD. can

Further, illustrative embodiments of the present disclosure will be described below primarily with reference to EHT, but it will be appreciated that exemplary embodiments of the present disclosure may be applied to other protocol standards, such as EHT+.

2 is a block diagram illustrating a wireless communication system 20 according to an exemplary embodiment of the present disclosure. Specifically, the block diagram of FIG. 2 shows an AP MLD 100 and a non-AP MLD 200 communicating with each other in a wireless communication system 20 . Each of the AP MLD 100 and the non-AP MLD 200 of FIG. 2 may be any device that communicates in the wireless communication system 20, and may be referred to as a device for wireless communication or simply a device.

Referring to FIG. 2 , the AP MLD 100 may include a radio frequency integrated circuit (RFIC) 110 and a processor 120. The RFIC 110 may include first to nth transceivers 111_1 to 111_n (where n is an integer greater than or equal to 2) and first to nth antennas 112_1 to 112_n. The RFIC 110 and the processor 120 may be included in one package or may be included in different packages, respectively. The non-AP MLD 200 may include an RFIC 210 and a processor 220. The RFIC 210 may include first to mth transceivers 211_1 to 211_m (where m is an integer greater than or equal to 2) and first to nth antennas 212_1 to 212_m. Hereinafter, a description of the non-AP MLD 200 overlapping with that of the AP MLD 100 will be omitted.

The first to n th antennas 112_1 to 112_n are coupled to the first to n th transceivers 111_1 to 111_n, respectively, and receive signals from the non-AP MLD 200 so that the first to n th transceivers ( 111_1 to 111_n) or signals provided from the first to nth transceivers 111_1 to 111_n may be transmitted to the non-AP MLD 200. In some embodiments, the first to nth antennas 112_1 to 112_n may include a phased array for beamforming.

The first to nth transceivers 111_1 to 111_n may process signals received from the non-AP MLD through the first to nth antennas 112_1 to 112_n, and the processed signals may be provided to the processor 120. can In addition, the first to nth transceivers 111_1 to 111_n may process signals provided from the processor 120 and output the processed signals through the first to nth antennas 112_1 to 112_n. In some embodiments, the first to nth transceivers 111_1 to 111_n may include analog circuits such as a low noise amplifier, a mixer, a filter, a power amplifier, and an oscillator. The first to nth transceivers 111_1 to 111_n may process signals received from the first to nth antennas 112_1 to 112_n and/or signals received from the processor 120 under the control of the processor 120. there is.

As an exemplary embodiment, the AP MLD 100 performs communication based on a plurality of links (ML) using the first to nth transceivers 111_1 to 111_n and the first to nth antennas 112_1 to 112_n. It can be performed with the non-AP MLD 200. Frequency bands to which each of the plurality of links (ML) is allocated may be different, and the AP MLD 100 uses the first to nth transceivers 111_1 to 111_n and the first to nth antennas 112_1 to 112_n. n number of APs may be supported through a control operation of the processor 120 . For example, the AP MLD 100 supports a first AP composed of a first transceiver 111_1 controlled by the processor 120 and a first antenna 112_1, and a second transceiver controlled by the processor 120. A second AP composed of (111_2) and a second antenna (112_2) may be supported.

In some embodiments, the AP MLD 100 may further include first individual processors (not shown) corresponding to each of the n APs, and the processor 120 may include first individual processors (not shown). By controlling, n APs may each perform an operation according to exemplary embodiments of the present disclosure. For example, the AP MLD 100 supports a 1st AP composed of a 1-1st individual processor (not shown), a 1st transceiver 111_1 and a 1st antenna 112_1, and a 1-2nd individual processor (not shown). ), a second AP composed of a second transceiver 111_2 and a second antenna 112_2 may be supported.

The processor 120 extracts information by demodulating and/or decoding signals received from the non-AP MLD 200 by processing signals received from the first to nth transceivers 111_1 to 111_n. can do. In addition, signals including information to be transmitted to the non-AP MLD 200 may be generated and provided to the first to nth transceivers 111_1 to 111_n. For example, the processor 120 transmits signals generated by coding and/or modulating data to be transmitted to the non-AP MLD 200 to the first through n-th transceivers 111_1 through 111_n. can provide In some embodiments, the processor 120 may include a programmable component such as a central processing unit (CPU), a digital signal processor (DSP), and the like, and may be reconfigurable, such as a field programmable gate array (FPGA). ) components, or components that provide fixed functions, such as IP (intellectual property) cores. In some embodiments, processor 120 may include or access memory that stores data and/or a series of instructions.

As an exemplary embodiment, the non-AP MLD 200 is based on a plurality of links (ML) using the first to m th transceivers 211_1 to 211_m and the first to m th antennas 212_1 to 212_n. Communication may be performed with the AP MLD 100. The non-AP MLD 200 may support m STAs through a control operation of the processor 220 using the first to m th transceivers 211_1 to 211_m and the first to m th antennas 212_1 to 212_n. For example, the non-AP MLD 200 supports a first STA composed of a first transceiver 211_1 controlled by the processor 220 and a first antenna 212_1, and a first STA controlled by the processor 220 A second STA composed of 2 transceivers 211_2 and a second antenna 212_2 may be supported. In some embodiments, the number of STAs supported by the non-AP MLD 200 may be less than or equal to that of the AP MLD 100, and the number of multiple links (ML) may be It may match the number of supporting STAs.

In some embodiments, the non-AP MLD 200 may further include second individual processors (not shown) corresponding to each of the m STAs, and the processor 220 may include second individual processors (not shown). ) By controlling m STAs may each perform an operation according to exemplary embodiments of the present disclosure. For example, the non-AP MLD 200 supports a first STA composed of a 2-1 individual processor (not shown), a first transceiver 211_1 and a first antenna 212_1, and a 2-2 individual processor (not shown), a second STA composed of a second transceiver 211_2 and a second antenna 212_2 may be supported.

In an exemplary embodiment, the processor 120 may include a frame alignment circuit 121 . The frame aligning circuit 121 is configured to effectively perform signaling of a protection mechanism performed to ensure reliability of communication using a plurality of links (ML) between the AP MLD 100 and the non-AP MLD 200. At least one of the additional frame length and cross-link related information may be adaptively controlled. Specifically, the AP MLD 100 and the non-AP MLD 200 transmit and receive mutual RTS (request to send) frames and CTS (clear to send) frames based on the protection mechanism, and based on the transmission and reception results Mutual data can be transmitted and received. At this time, the frame alignment circuit 121 configures the RTS frame so that the AP MLD 100 can receive CTS frames from at least two of the plurality of links ML from the non-AP MLD 200 in a mutually aligned state. After determining at least one of the additional length and cross-link related information, and generating an RTS frame based on the determination result, it may be transmitted to the non-AP MLD 200 through the RFIC 110. Also, as an exemplary embodiment, the frame alignment circuit 121 may determine whether to transmit another RTS frame based on the determination result. For example, in determining cross-link related information for another link, when it is determined that the other link has a cross-link relationship with the corresponding link, the frame alignment circuit 121 may omit transmission of the RTS frame through the other link. can As another example, in determining the cross-link related information for another link, when it is determined that the other link does not have a cross-link relationship with the corresponding link, the frame alignment circuit 121 may transmit the RTS frame through the other link. can Also, in an embodiment in which only the additional length of the RTS frame is determined, the frame aligning circuit 121 may transmit the RTS frame through another link. Details of the cross-link relationship will be described later.

In some embodiments, the processor 220 of the non-AP MLD 200 may also include a frame alignment circuit that performs the same or similar operation as the frame alignment circuit 121 of the AP MLD 100 .

3 is a block diagram illustrating a wireless communication system 30 according to an exemplary embodiment of the present disclosure. Specifically, the block diagram of FIG. 3 shows the AP MLD 300 and the non-AP MLD 400 communicating with each other using the first to third links L1, L2, and L3 in the wireless communication system 30. .

As an exemplary embodiment, the AP MLD 300 includes first to third APs (AP1, AP2, and AP3), and the non-AP MLD 400 includes first to third STAs (STA1, STA2, and STA3) can include In some embodiments, different from that shown in FIG. 3 , the AP MLD 300 and the non-AP MLD 400 may communicate with each other using two or more than three links, a number corresponding thereto. of APs and STAs, respectively.

The first to third APs (AP1, AP2, and AP3) and the first to third STAs (STA1, STA2, and STA3) may set up the first to third links L1, L2, and L3, respectively. For example, the AP MLD 300 and the non-AP MLD 400 may perform an access procedure and/or a negotiation procedure for multi-link operation. The non-AP MLD 400 may identify a usable band in communication with the AP MLD 300, and use two or more links among links supported by the AP MLD 300 for multi-link. (300) can be negotiated. This mutual communication method using two or more links may be referred to as multi-link operation (MLO). Due to the multi-link operation, the wireless communication system 30 can provide high throughput.

4A and 4B are timing diagrams illustrating examples of multi-link operation. Specifically, FIGS. 4A and 4B show an example of a multi-link operation performed in the wireless communication system 30 of FIG. 3 . In the following, FIGS. 4A and 4B are described with reference to FIG. 3 .

The AP MLD 300 and the non-AP MLD 400 of FIG. 3 may support simultaneous transmit and receive (STR). For example, the AP MLD 300 transmits data to the non-AP MLD 400 over a first link L1 and simultaneously receives data from the non-AP MLD 400 over a second link L2. can do. The first to third APs (AP1, AP2, and AP3) may have different medium access control (MAC) addresses, respectively, and may be in charge of the first to third links L1, L2, and L3, respectively. Accordingly, each of the first to third APs (AP1, AP2, and AP3) may function as an independent AP. In addition, the first to third STAs (STA1, STA2, and STA3) may have different MAC addresses, respectively, and each of the first to third STAs (STA1, STA2, and STA3) may function as independent STAs. The AP MLD 300 and the non-AP MLD 400 may mutually communicate in multi-band. For example, the first link L1 may use a bandwidth (eg, 40 MHz) in a 2.4 GHz band, the second link L2 may use a bandwidth (eg, 160 MHz) in a 5 GHz band, and a third link (L3) may use a bandwidth (eg, 160 MHz) in the 6 GHz band.

Referring to FIG. 4A , at time t11, the first AP (AP1) may initiate transmission of the first data (D1) on the first link (L1), and the first STA (STA1) may transmit the first data (D1). ) can be received. While the first AP (AP1) transmits the first data (D1), the second STA (STA2) may initiate transmission of the second data (D2) on the second link (L2) at time t12, The second AP (AP2) may receive the second data (D2). Although transmission of the first data D1 and transmission of the second data D2 overlap in the time domain, the first STA (STA1) and the second AP (AP2) transmit the first data D1 due to the STR. and the second data D2 may be received respectively. In addition, while the first AP (AP1) transmits the first data (D1) and the second STA (STA2) transmits the second data (D2), the third AP (AP3) at time t31 transmits the third link ( Transmission of the third data D3 may be started on L3), and the third STA (STA3) may receive the third data D3. Although transmission of the first data D1, transmission of the second data D2, and transmission of the third data D3 overlap in the time domain, the first STA (STA1) and the second AP ( AP2) and the third STA (STA3) may receive the first data D1, the second data D2, and the third data D3, respectively.

Meanwhile, in multi-link operation, links with difficult STR may exist. For example, if the frequency bands of the links are not sufficiently spaced apart, interference may occur between the links, and accordingly, the corresponding links may be links with difficult STR. In addition, when there is interference between links due to various causes including structural limitations due to light, thin, and compact hardware within the non-AP MLD, the corresponding links may have difficulty in STR. In this way, the links of the multi-link operation may include a non-STR link group composed of links with difficult STR. In particular, two links with difficult STR due to mutual interference in the non-STR link group are non-STR links. can be referred to as a pair. The non-STR link group may be identified in a process in which the AP MLD 300 and the non-AP MLD 400 set up the first to third links L1, L2, and L3.

Referring further to FIG. 4B, it is assumed that the first link L1 and the second link L2 are a non-STR link pair. For example, the first link L1 may use a 6 GHz band, and the second link L2 may use a 5 GHz band. At time t21, the first AP (AP1) may obtain a transmit opportunity (TXOP), may initiate transmission of the first data (D1) over the first link (L1), and may transmit the first data (D1) to the first STA (STA1) may receive the first data D1. At time t22, the second STA (STA2) may initiate transmission of the second data (D2) on the second link (L2), but the first link (L1) and the second link (L2) are non-STR In the case of a link pair, interference may occur between transmission of the second data D2 and reception of the first data D1 at the non-AP MLD 400 side. For example, the second data D2 may not be properly transmitted through the second link L2 because the first data D1 is leaked through a path through which the second data D2 is transmitted from the second STA (STA2). there is. Such interference may also occur in signaling of a protection mechanism between the AP MLD 300 and the non-AP MLD 400 and will be described later in FIG. 5 . Meanwhile, it is assumed that the first link L1 and the second link L2 described in the drawings below are a non-STR link pair.

5 is a timing diagram including signaling based on a protection mechanism in multi-link operation. Specifically, FIG. 5 shows an example of a multi-link operation performed in the wireless communication system 30 of FIG. 3 . In the following, FIG. 5 is described with reference to FIG. 3 . It is assumed that the protection mechanism is activated in the first and second links L1 and L2.

5, at time t13, the first AP (AP1) may initiate transmission of the first RTS frame (RTS1) on the first link (L1), and the first STA (STA1) may transmit the first RTS frame (RTS1) can be received. At time t33, which is after a short interframe space (SIFS) from time t23, the first STA (STA1) initiates transmission of the first CTS frame (CTS1) on the first link (L1) as a response to the first RTS frame (RTS1) and the first AP (AP1) can receive the first CTS frame (CTS1). At time t63 after SIFS from time t53, the first AP (AP1) transmits a first aggregated-MAC protocol data unit (A-MPDU) (A- MPDU1) may be transmitted, and the first STA (STA1) may receive the first A-MPDU (A-MPDU1).

At time t23, the second AP (AP2) may initiate transmission of the second RTS frame (RTS2) on the second link (L2), and the second STA (STA2) may receive the second RTS frame (RTS2). can At time t53, which is after a short interframe space (SIFS) from time t43, the second STA (STA2) initiates transmission of the second CTS frame (CTS2) on the second link (L2) as a response to the second RTS frame (RTS2) and the second AP (AP2) can receive the second CTS frame (CTS2). At time t83 after SIFS from time t73, the second AP (AP2) can initiate transmission of a second A-MPDU (A-MPDU2) over the second link (L2) as a response to the second CTS frame (CTS2) And, the second STA (STA2) may receive the second A-MPDU (A-MPDU2). The AP MLD 300 may control the end of the first A-MPDU (A-MPDU1) and the end of the second A-MPDU (A-MPDU2) to be aligned at time t93.

From time t33 to time t43, since the first link L1 and the second link L2 are non-STR link pairs, the non-AP MLD 400 transmits the first CTS frame (CTS1) and the second RTS frame Interference between receptions of (RTS2) may occur. Due to the above interference, smooth protection mechanism signaling is difficult, and this may adversely affect reliability of data communication.

The AP MLD 300 according to an exemplary embodiment of the present disclosure determines at least one of the additional length of the first RTS frame (RTS1) and cross-link related information to determine the second RTS frame in the non-AP MLD 400. Interference between reception of RTS2 and transmission of the first CTS frame (CTS1) can be avoided. That is, the AP MLD 300 generates a first RTS frame (RTS1) for aligning the first CTS frame (CTS1) and the second CTS frame (CTS2) to the non-AP MLD through the first link (L1). (400). As an exemplary embodiment, the format of the first RTS frame (RTS1) is any one of a plurality of trigger formats defined in the standard specification in order to properly arrange padding data or cross-link related information corresponding to the additional length. By adopting one or newly defining it, it is possible to support signaling of an efficient protection mechanism.

A method of generating the first RTS frame (RTS1) of the AP MLD 300 may have various embodiments, and the embodiments are described in FIGS. 6A to 13C. There may be various embodiments of the format of the first RTS frame (RT1), and the embodiments are described in FIGS. 14A to 18.

6A and 6B are flowcharts illustrating a method of operating an AP MLD according to an exemplary embodiment of the present disclosure. It is assumed that the kth AP and other APs described below are included in the AP MLD. Also, in the following description, the RTS frame is transmitted from the AP MLD to the non-AP MLD, but the present disclosure is not limited thereto, and the RTS frame is transmitted from the non-AP MLD to the AP MLD. It will be fully understood that the technical ideas of can be applied.

Referring to FIG. 6A , in step S100, the k th AP may enter a transmission preparation period of the k th RTS frame of the k th AP. In this specification, an operation of a specific AP may be interpreted as an operation of an AL MLD. In addition, in this specification, the transmission preparation period of the RTS frame is a period for determining at least one of the additional length of the RTS frame and cross-link related information, and may be set before transmission timing of the RTS frame arrives. However, the transmission preparation period of the RTS frame is arbitrarily named to help understanding of exemplary embodiments of the present disclosure, and the present disclosure is not limited thereto. In addition, in some embodiments, the AP MLD may perform an operation of generating an RTS frame according to an exemplary embodiment of the present disclosure in an arbitrary section without setting a separate preparation section for transmission of the RTS frame. For example, the transmission preparation period of the RTS frame may be entered in response to a back-off count for transmission of the RTS frame of the corresponding AP reaching a reference value. For example, when the back-off count of the AP gradually decreases from a predetermined value and reaches a reference value, the corresponding AP may enter a transmission preparation period of the RTS frame.

In step S110, the kth AP may obtain information related to transmission of RTS frames of APs other than the kth AP. Meanwhile, other APs may be limited to those corresponding to links having a non-STR link pair relationship with the kth link corresponding to the kth AP. As an exemplary embodiment, information related to transmission of RTS frames of other APs may include whether a protection mechanism is activated in links corresponding to other APs and back-off counts of other APs for transmission of RTS frames. . In the transmission preparation period of the k-th RTS frame, the k-th AP may check in advance an RTS frame having transmission timing close to another AP capable of transmitting the RTS frame through transmission information of the RTS frames and the transmission timing of the k-th RTS frame. there is.

In step S120, the kth AP may generate a kth E (extended)-RTS frame based on the information acquired in step S110. As an exemplary embodiment, the k th AP determines the additional length of the k th RTS frame based on the transmission timing of the RTS frame of another AP, and adds padding data corresponding to the additional length to the k th RTS frame. By doing so, the k th E-RTS frame can be generated.

In step S130, the kth AP may exit the transmission preparation period and transmit the kth E-RTS frame. Then, the other AP may transmit the RTS frame, and the end of the kth E-RTS frame transmitted from the kth AP may be aligned with the end of the RTS frame transmitted from the other AP.

6B is a flowchart showing steps S120 and S130 of FIG. 6A in detail. Referring further to FIG. 6B , following step S110 ( FIG. 6A ), in step S121 , the k th AP may check whether an RTS frame that can be aligned with the k th RTS frame exists. In this case, the alignable RTS frame may refer to an RTS frame to be transmitted so as to have an end alignable with the end of the k th RTS frame.

When step S121 is 'YES', subsequent to step S122, the kth AP may generate the kth E-RTS frame from the kth RTS frame. Specifically, the k-th AP may determine the additional length based on the difference between the transmission timing of the RTS frame to be aligned of the identified AP and the transmission timing of the k-th RTS frame of the k-th AP, and transmit padding data corresponding to the additional length. The k th E-RTS frame may be generated by generating and adding to the k th RTS frame. In some embodiments, a plurality of RTS frames that can be aligned with the k-th RTS frame may be identified in step S121, and at this time, the plurality of corresponding APs including the k-th AP are based on the transmission timing of the latest RTS frame to be aligned. In this way, the kth E-RTS frame and the E-RTS frames to be aligned may be generated by adding padding data to the kth RTS frame and the RTS frames to be aligned, respectively.

In step S131, the kth AP may transmit the kth E-RTS frame. The k th E-RTS frame may be longer than the RTS frame to be aligned.

When step S121 is 'NO', following step S132, the AP MLD may transmit the kth RTS frame. The kth RTS frame may have the same length as the RTS frame to be aligned.

7 is a timing diagram illustrating an example of multi-link operation according to an exemplary embodiment of the present disclosure.

Referring to FIG. 7 , while the first link L1 is not busy, the back-off count of the first AP (AP1) corresponding to the first link L1 may decrease, and the second link L2 The back-off count of the second AP (AP2) corresponding to the second link (L2) may decrease while is not in a busy state. At time t14, the first link (L1) may enter a busy state due to other transmissions, and the back-off count of the first AP (AP1) may stop decrementing. Similarly, at time t24, the second link (L2) may enter a busy state due to other transmissions, and the back-off count of the second AP (AP2) may stop decrementing.

At time t34, the busy state of the first link L1 may be released, and accordingly, the back-off count of the first AP AP1 may gradually decrease from 4. In some embodiments, the release of the busy state may be referred to as a ready state (or idle state). Similarly, at time t44, the busy state of the second link L2 may be released, and accordingly, the back-off count of the second AP (AP2) may gradually decrease from 3. Also, at time t44, the first AP (AP1) may enter the transmission preparation period (TPP) of the first RTS frame (RTS1) in response to the back-off count reaching 1. However, this is an exemplary embodiment and is not limited thereto, and the first AP (AP1) transmits a preparation period (TPP) of the first RTS frame (RTS1) in response to the back-off count reaching another arbitrary reference value ) can enter.

In the transmission preparation period (TPP), the first AP (AP1) may obtain transmission related information of the second RTS frame (RTS2) of the second AP (AP2). Specifically, the first AP (AP1) may obtain the back-off count of the second AP (AP2). At this time, the first AP (AP1) determines that the difference between the back-off count of 1 of the first AP (AP1) and the back-off count of 3 of the second AP (AP2) at time t44 is within the reference difference. By checking, the second RTS frame (RTS2) can be determined as the RTS frame to be aligned. In the transmission preparation period (TPP), the first AP (AP1) is based on the difference between the back-off count of 1 of the first AP (AP1) and the back-off count of 3 of the second AP (AP2) at time t45 The additional length of the first RTS frame may be determined and padding data corresponding to the additional length may be added to the first RTS frame to generate the first E-RTS frame (E-RTS1). As an exemplary embodiment, the unit length of the padding data may correspond to the unit length of the back-off count.

At time t54, the back-off count of the first AP (AP1) reaches 0, so the first AP (AP1) exits the transmission preparation period (TPP) and connects to the first STA (STA1) through the first link (L1). The first E-RTS frame (E-RTS1) may be transmitted.

At time t64, the back-off count of the second AP (AP2) reaches 0, so the second AP (AP2) sends the second RTS frame (RTS2) to the second STA (STA2) through the second link (L2). can transmit The transmission timing of the first E-RTS frame (E-RTS1) and the transmission timing of the second RTS frame (RTS2) are different, but the end of the first E-RTS frame (E-RTS1) is the second RTS frame (RTS2) can be aligned with the end of

When the first STA (STA1) senses the first link (L1) and confirms that it is in the ready state, from time t84 to time t94 after SIFS, the first STA (STA1) transmits the first AP through the first link (L1). The first CTS frame (CTS1) may be transmitted to (AP1). When the second STA (STA2) senses the second link (L2) and confirms that it is in the ready state, from time t84 to time t94 after SIFS, the second STA (STA2) transmits the second AP through the second link (L2). The second CTS frame (CTS2) may be transmitted to (AP2). Accordingly, the first CTS frame CTS1 and the second CTS frame CTS2 may be mutually aligned. In some embodiments, the sensing operation for the first link L1 of the first STA (STA1) and the sensing operation for the second link L2 of the second STA (STA2) may be performed from time t74 to time t84 there is. In this specification, a sensing operation for a link may be referred to as a link sensing operation.

At time t104 after SIFS from time t94, the first AP (AP1) may transmit a first A-MPDU (A-MPDU1) to the first STA (STA1) through the first link (L1), and the second AP (AP2) may transmit the second A-MPDU (A-MPDU2) to the second STA (STA2) through the second link (L2).

8A and 8B are flowcharts illustrating a method of operating an AP MLD according to an exemplary embodiment of the present disclosure. In the following description, the RTS frame is transmitted from the AP MLD to the non-AP MLD, but the present disclosure is not limited thereto. It will be fully understood that the idea can be applied. In addition, in the following description, overlapping contents with those of FIGS. 6A and 6B are omitted.

Referring to FIG. 8A , in step S200, the k th AP may enter a transmission preparation period of the k th RTS frame of the k th AP.

In step S210, the kth AP may obtain information related to transmission of RTS frames of APs other than the kth AP. Meanwhile, other APs may be limited to those corresponding to links having a non-STR link pair relationship with the kth link corresponding to the kth AP.

In step S220, the kth AP may generate a kth cross link (CL)-RTS frame based on the information acquired in step S210. As an exemplary embodiment, the k th AP determines cross-link related information of the k th RTS frame based on the transmission timing of the RTS frame of another AP, and transmits data corresponding to the determined cross-link related information to the k th RTS frame. By filling in, the kth CL-RTS frame can be generated. As an exemplary embodiment, the cross-link related information includes a link index indicating a plurality of links, information indicating whether sensing is required for each of the plurality of links, and resource information allocated to the plurality of links for transmission of CTS frames. may contain at least one. In some embodiments, the cross-link related information may further include information indicating whether a CTS frame can be transmitted through an alternate link for each of a plurality of links.

As an exemplary embodiment, the format of the k th RTS frame includes a plurality of fields corresponding to cross-link related information, wherein the plurality of fields include a first field indicating a plurality of links, whether link sensing is performed for the plurality of links. It may include a second field indicating , and a third field indicating resources allocated to a plurality of links for transmission of CTS frames. In some embodiments, the format of the kth RTS frame is a padding field filled with padding data whose length is variable according to a fourth field indicating whether or not a CTS frame can be transmitted through an alternative link for each of a plurality of links and an additional length. At least one of them may be further included.

As an exemplary embodiment, the format of the k th RTS frame includes a plurality of individual fields corresponding to cross-link related information, each of the plurality of individual fields includes a first subfield representing a specific link, and a link to the specific link. It may include a second subfield indicating whether sensing is required and a third subfield indicating resources allocated to a specific link for transmission of the CTS frame. In some embodiments, each of the plurality of individual fields included in the format of the k th RTS frame may further include a fourth subfield indicating whether transmission of the CTS frame through an alternative link for a specific link is possible. Also, in some embodiments, the format of the kth RTS frame may further include a padding field filled with padding data whose length is variable according to the additional length described above with reference to FIGS. 6A to 7 .

As an exemplary embodiment, the format of the kth RTS frame may correspond to one of a plurality of trigger frame types proposed in the IEEE 802.11ax standard. In this case, the format of the kth RTS frame may include a common information field and a user information field, and cross-link related information may be disposed in either one of the common information field and the user information field.

In step S230, the kth AP may exit the transmission preparation period and transmit the kth CL-RTS frame. Meanwhile, transmission of the kth CL-RTS frame may replace transmission of an RTS frame of another AP, and thus transmission of an RTS frame of another AP may be omitted.

FIG. 8B is a flowchart showing step S220 of FIG. 8A in detail. Referring further to FIG. 8B , following step S210 ( FIG. 8A ), in step S221 , the k th AP may detect a link requiring sensing among other links other than the k th link corresponding to the k th AP. The detected link may be referred to as having a cross-link relationship with the kth link. In this specification, sensing for a link may refer to an operation of sensing whether the state of a corresponding link is busy. As an exemplary embodiment, the kth AP may detect a link on which transmission of an RTS frame having a close transmission timing is scheduled from the transmission timing of the kth RTS frame.

In step S222, the kth AP may generate the kth CL-RTS frame based on the detection result of step S221. For example, information indicating that link sensing is necessary for a link index corresponding to a detected link and resource information allocated to a k th link for transmission of a CTS frame are filled in the k th RTS frame to form a k th CL-RTS frame. can create Thereafter, step S230 (FIG. 8A) may follow.

9 is a table diagram for explaining cross-link related information (INFO1) according to an exemplary embodiment of the present disclosure.

Referring to FIG. 9, cross-link related information (INFO1) includes 'Link Index' information indicating each of a plurality of links, 'Link Sensing Required' information indicating whether sensing of each of a plurality of links is required, and transmission of CTS frames. may include 'resource unit (RU) allocation' information indicating resources allocated to a plurality of links for The cross-link related information (INFO1) may further include information necessary for CTS frame transmission of an AP (eg, the AP detected in step S221 of FIG. 8B) that does not directly receive an RTS frame through its assigned link. 'Reserved' space may exist so that such information can be placed in the future.

10A and 10B are flowcharts illustrating an operation method of an AP MLD 500 and a non-AP MLD 600 according to an exemplary embodiment of the present disclosure. As shown in FIG. 10A , the AP MLD 500 may include a kth AP (APk) and other APs (APs), and the non-AP MLD 600 may include a kth AP (APk) and a kth AP (APk). It may include a kth STA (STAk) and other STAs (STAs) communicating over the link. Hereinafter, a case in which an RTS frame is transmitted from the AP MLD 500 to the non-AP MLD 600 is mainly described, but the present disclosure is not limited thereto, and the non-AP MLD 600 to the AP MLD 500 It will be fully understood that the technical idea of the present disclosure can be applied even when the RTS frame is transmitted with .

Referring to FIG. 10A , in step S300, the kth AP (APk) may transmit the kth CL-RTS frame through the kth link. As described above, the kth CL-RTS frame may indicate a link among other links (APs) on which link sensing needs to be performed in response to the kth CL-RTS frame, and may indicate resources for transmission of the CTS frame. The AP MLD 500 may omit transmission of the RTS frame through a link having a cross-link relationship with the kth link. For example, when the second link is sensed based on the CL-RTS frame transmitted through the first link, the first link and the second link may be referred to as having a mutual cross-link relationship. Meanwhile, since the k th CL-RTS frame is used for sensing a link having a cross-link relationship with the k th link, transmission of the RTS frame through the corresponding link may be omitted.

In step S310, the non-AP MLD 600 may provide cross-link related information of the kth CL-RTS frame to other STAs (STAs).

In step S320, a selected STA among other STAs (STAs) may perform link sensing based on cross-link related information. The selected STA may be an STA corresponding to a link requiring sensing in cross-link related information. In this specification, an operation of a specific STA may be interpreted as an operation of a non-AP MLD.

The STA selected in step S330 may transmit the CTS frame to an AP corresponding to the selected STA among other APs through a link allocated to the selected STA based on the sensing result in step S320. Although not shown, the kth STA (STAk) senses the kth link in response to the kth CL-RTS frame, and transmits the kth CTS frame to the kth AP (APk) through the kth link based on the sensing result. can transmit

FIG. 10B is a flowchart showing step S330 of FIG. 10A in detail. Referring further to FIG. 10B, in step S331a following step S320 (FIG. 10a), the selected STA responds to the kth CL-RTS frame to determine whether the corresponding link, that is, the link assigned to it is busy. there is.

When step S331a is 'YES', subsequent to step S332a, the selected STA may not transmit the CTS frame through the corresponding link. When step S331a is 'NO', subsequent to step S333a, the selected STA may transmit a CTS frame through a corresponding link.

11 is a table diagram for explaining cross-link related information (INFO2) according to an exemplary embodiment of the present disclosure. Hereinafter, differences from the cross-link related information (INFO1) of FIG. 9 will be mainly described.

Referring to FIG. 11, cross-link related information (INFO2) is 'non-primary' indicating whether a CTS frame can be transmitted through an alternate link for each of a plurality of links, rather than cross-link related information (INFO1) of FIG. TX' information may be further included. Specifically, the 'non-Primary TX' information indicates that the link assigned to the STAs or APs of the device (eg, AP MLD or non-AP MLD) is currently busy and transmits the CTS frame to the link assigned to the link When transmission is not possible through , it is possible to indicate for each link whether to transmit the CTS frame through an alternative link by detecting an alternative link in a ready state among other links.

FIG. 12 is a flowchart illustrating a specific embodiment of step S330 of FIG. 10A using the cross-link related information (INFO2) of FIG. 11 .

Referring to FIG. 12, in step S331b following step S320 (Fig. 10a), the selected STA responds to the kth CL-RTS frame to determine whether the corresponding link, that is, the link assigned to it is busy. .

When step S331b is 'YES', subsequent to step S332b, the selected STA can check whether the value corresponding to the link is '1' by referring to the 'non-Primary TX' information of FIG. 11 .

When step S333b is 'YES', subsequent to step S333b, the selected STA may perform a detection operation on an alternate link currently in a ready state among other links and check whether the alternate link is detected.

When step S333b is 'YES', subsequent to step S334b, the selected STA may transmit the CTS frame through the detected alternative link.

When step S331b is 'NO', subsequent to step S335b, the selected STA may transmit a CTS frame through the corresponding link.

When at least one of steps S332b and step S333b is 'NO', subsequent to step S336b, the selected STA may not transmit the CTS frame.

13A-13C are timing diagrams illustrating examples of multi-link operation according to example embodiments of the present disclosure. Hereinafter, contents overlapping with those of FIG. 7 are omitted.

Referring to FIG. 13A , at time t15, the first link (L1) may enter a busy state due to other transmissions, and the back-off count of the first AP (AP1) may stop decreasing. Similarly, at time t25, the second link (L2) may enter a busy state due to other transmissions, and the back-off count of the second AP (AP2) may stop decrementing.

At time t35, the busy state of the first link L1 may be released, and accordingly, the back-off count of the first AP AP1 may gradually decrease from 4. Similarly, at time t45, the busy state of the second link L2 may be released, and accordingly, the back-off count of the second AP (AP2) may gradually decrease from 3. Also, at time t45, the first AP (AP1) may enter a transmission preparation period (TPP) of the first RTS frame in response to the back-off count reaching 1.

In the transmission preparation period (TPP), the first AP (AP1) may obtain transmission related information of the second RTS frame (RTS2) of the second AP (AP2). Specifically, the first AP (AP1) may obtain information indicating that the protection mechanism is activated in the second link (L2) corresponding to the second AP (AP2) and the back-off count of the second AP (AP2). there is. At this time, the first AP (AP1) determines that the difference between the back-off count of 1 of the first AP (AP1) and the back-off count of 3 of the second AP (AP2) at time t45 is within the reference difference. By checking, the second link L2 can be detected as a link requiring sensing. In the transmission preparation period (TPP), the first AP (AP1) may determine cross-link related information based on the detection result. Specifically, the AP MLD indicates that sensing for the second link (L2) is required, and is cross-link related to indicate resources allocated for transmission of the second CTS frame (CTS2) through the second link (L2). information can be determined. In the transmission preparation period (TPP), the first AP (AP1) may generate the first CL-RTS frame (CL-RTS1) by filling the first RTS frame with data corresponding to the determined cross-link related information.

At time t55, the back-off count of the first AP (AP1) reaches 0, so the first AP (AP1) exits the transmission preparation period (TPP) and connects to the first STA (STA1) through the first link (L1). The first CL-RTS frame (CL-RTS1) may be transmitted.

At time t65, the back-off count of the second AP (AP2) reaches 0, and transmission of the second RTS frame of the second AP (AP2) may be omitted.

From time t75 to t95, the second STA (STA2) receives the cross-link related information included in the first CL-RTS frame (CL-RTS1) and transmits information to the second link (L2) based on the cross-link related information. It is possible to perform a sensing operation (SO) for The second STA (STA2) may confirm that the second link (L2) is in a ready state through the sensing operation (SO). The execution timing and execution time of the sensing operation SO shown in FIG. 13A are merely exemplary embodiments, but are not limited thereto, and the first CTS frame CTS1 and the second CTS frame CTS2 can be aligned. The sensing operation SO for the second link L2 may be performed with appropriate timing and execution time.

When the first STA (STA1) senses the first link (L1) and confirms that it is in the ready state, from time t85 to time t95 that is after SIFS, the first STA (STA1) connects the first AP through the first link (L1). The first CTS frame (CTS1) may be transmitted to (AP1). When the second STA (STA2) senses the second link (L2) and confirms that it is in the ready state, from time t85 to time t95 after SIFS, the second STA (STA2) transmits the second AP through the second link (L2). The second CTS frame (CTS2) may be transmitted to (AP2).

At time t115 after SIFS from time t105, the first AP (AP1) may transmit a first A-MPDU (A-MPDU1) to the first STA (STA1) through the first link (L1), and the second AP (AP2) may transmit the second A-MPDU (A-MPDU2) to the second STA (STA2) through the second link (L2).

The operation from time t16 to time t76 in FIG. 13B may be the same as the operation from time t15 to time t75 in FIG. 13A , and accordingly, operations after time t76 that are different from those of FIG. 13A will be mainly described.

13B, at times t76 to t96, the second STA (STA2) receives cross-link related information included in the first CL-RTS frame (CL-RTS1), and based on the cross-link related information A sensing operation SO for the second link L2 may be performed. The second STA (STA2) may confirm that the second link L2 is busy through the sensing operation SO.

When the first STA (STA1) senses the first link (L1) and confirms that it is in the ready state, from time t86 to time t96 after SIFS, the first STA (STA1) transmits the first AP through the first link (L1). The first CTS frame (CTS1) may be transmitted to (AP1). When the second STA (STA2) senses the second link (L2) and confirms that it is busy, it may not transmit the second CTS frame.

At time t117 after SIFS from time t106, the first AP (AP1) may transmit a first A-MPDU (A-MPDU1) to the first STA (STA1) through the first link (L1).

The operation from time t17 to time t77 in FIG. 13c may be the same as the operation from time t15 to time t75 in FIG.

Referring further to FIG. 13C, at times t77 to t97, the second STA (STA2) receives cross-link related information included in the first CL-RTS frame (CL-RTS1), and based on the cross-link related information A sensing operation SO for the second link L2 may be performed. The second STA (STA2) may confirm that the second link L2 is busy through the sensing operation SO. At this time, the second STA (STA2) may sense the state of the third link (L3).

When the first STA (STA1) senses the first link (L1) and confirms that it is in the ready state, from time t87 to time t97 after SIFS, the first STA (STA1) transmits the first AP through the first link (L1). The first CTS frame (CTS1) may be transmitted to (AP1). When the second STA (STA2) confirms the ready state through the sensing operation (SO) for the third link (L3), it detects the third link (L3) as an alternative link, and from time t87 to time t97 after SIFS, The second STA (STA2) may transmit the second CTS frame (CTS2) to the second AP (AP2) through the third link (L3), which is an alternative link.

At time t117 after SIFS from time t107, the first AP (AP1) may transmit a first A-MPDU (A-MPDU1) to the first STA (STA1) through the first link (L1), and the second AP (AP2) may transmit the second A-MPDU (A-MPDU2) to the second STA (STA2) through the third link (L3), which is an alternative link. In some embodiments, the second AP (AP2) may transmit a second A-MPDU (A-MPDU2) to the second STA (STA2) through the second link (L2).

14A and 14B are diagrams illustrating formats FF1 and FF2 of RTS frames according to exemplary embodiments of the present disclosure.

Referring to FIG. 14A, the RTS frame format (FF1) may include a common field (CF) in which cross-link related information for a plurality of links is arranged and a 'Padding' field in which padding data is arranged. The common field (CF) is a 'Link ID' field indicating a plurality of links, a 'Link Sensing Required' field indicating whether link sensing is required for a plurality of links, resources allocated to a plurality of links for transmission of CTS frames It may include a 'RU Allocation' field indicating the , and a 'non-Primary TX' field indicating whether transmission of the CTS frame through an alternate link is possible for a plurality of links. However, the format FF1 of the RTS frame shown in FIG. 14A is only an exemplary embodiment, but is not limited thereto, and the format FF1 of the RTS frame does not include some fields, It may contain more fields. Also, names of fields may be defined with other names. In this specification, the common field (CF) may be defined as a field in which cross-link related information commonly decoded by a plurality of APs or a plurality of STAs of a device receiving an RTS frame is disposed.

Referring further to FIG. 14B, the RTS frame format (FF2) may include a plurality of individual fields (IF_1 to IF_N) and a 'Padding' field in which padding data is disposed. Individual fields (IF_1 to IF_N) include a 'Specific Link ID' subfield indicating a specific link, a 'Link Sensing Required' subfield indicating whether a specific link needs link sensing, and resources allocated to a specific link for transmission of the CTS frame. It may include a 'RU Allocation' subfield indicating and a 'non-Priamary TX' subfield indicating whether transmission of a CTS frame through an alternative link for a specific link is possible. However, the RTS frame format FF2 shown in FIG. 14B is only an exemplary embodiment, and is not limited thereto, and the RTS frame format FF2 does not include some subfields or is not shown in FIG. 14B. may further include subfields that are not included. Also, names of subfields may be defined with other names. In this specification, individual fields IF_1 to IF_N may be defined as fields in which cross-link related information decoded by a specific AP or a specific STA of a device receiving an RTS frame is disposed.

15 is a diagram for explaining an embodiment in which cross-link related information is arranged in a format (T_FF) of a trigger frame according to an exemplary embodiment of the present disclosure.

Referring to FIG. 15, the format of the RTS frame may correspond to the format (T_FF) of the trigger frame. The format of the trigger frame (T_FF) is 'Frame Control' field, 'Duration' field, 'RA (reveiver address)' field, 'TA (transmitting AP's address)' field, 'Common Info' field (or common information field) (CIF), 'User Info' fields (or user information fields) (UIFs), 'Padding' field and 'FCS' field. The 'MAC header' may include a 'Frame Control' field, a 'Duration' field, a 'RA' field, and a 'TA' field.

As an exemplary embodiment, cross-link related information according to the technical idea of the present disclosure may be disposed in any one of a 'Common Info' field (CIF) and 'User Info' fields (UIFs).

FIG. 16 is a diagram for explaining trigger frame formats adoptable to an RTS frame format according to an exemplary embodiment of the present disclosure.

Referring to FIG. 16, according to IEEE 802.11.ax, trigger frame formats include 'Basic Trigger Frame' format, 'Beamforming Report (BFRP)' format, 'Multi-user block ack request (MU-BAR)' format, and 'Multi-user block ack request (MU-BAR)' format. -user request to send (MU-RTS)' format, 'Buffer Status Report (BSRP)' format, 'GSR MU-BAR' format, 'Bandwidth Query Report (BQRP)' format and 'NDP Feedback Report Poll (NFRP)' format can be included.

As an exemplary embodiment, any one of a plurality of formats may be adopted as the format of the RTS frame. However, this is an exemplary embodiment and is not limited thereto, and any one of arbitrary frame formats defined in more diverse standards may be adopted as the RTS frame format. 17 and 18 are described on the premise that the 'Multi-user request to send' format (hereinafter referred to as the 'MU-RTS' format) is adopted for the format of the RTS frame.

17 and 18 are diagrams for explaining RTS frames employing the 'MU-RTS' format according to exemplary embodiments of the present disclosure. In the following, FIG. 15 is further referred to for better understanding.

15 and 17, the common information field (CIF) includes a 'Trigger Type' subfield, a 'UL Length' subfield, a 'More TF' subfield, a 'CS Required' subfield, and a 'UL BW' subfield. , 'GI And HE-LTF Type' subfield, 'MU-MIMO HE-LTF Mode' subfield, 'Number Of EHT-LTF Symbols And Midamble Periodicity' subfield, 'UL STBC' subfield, 'LDPC Extra Symbol Segment ' subfield, 'AP Tx Power' subfield, 'Pre-FEC Padding Factor' subfield, 'PE Disambiguity' subfield, 'UL Spatial Reuse' subfield, 'Doppler' subfield, 'HE/EHT P160' subfield field, 'Special User into Field Present' subfield, 'Reserved' subfields, and 'Trigger Dependent Common Info' subfield.

In the 'MU-RTS' format, 'UL Length' subfield, 'GI And HE-LTF Type' subfield, 'MU-MIMO HE-LTF Mode' subfield, 'Number Of EHT-LTF Symbols And Midamble Periodicity' subfield , 'UL STBC' subfield, 'LDPC Extra Symbol Segment' subfield, 'AP Tx Power' subfield, 'Pre-FEC Padding Factor' subfield, 'PE Disambiguity' subfield, 'UL Spatial Reuse' subfield, The 'Doppler' subfield, the 'HE/EHT P160' subfield, and the 'Special User into Field Present' subfield may not be used and may be in a reserved state so that other data can be arranged.

As an exemplary embodiment, the cross-link related information (CF_CLI) disposed in the common field (CF) in FIG. 14A includes a 'UL Length' subfield, a 'GI And HE-LTF Type' subfield, and a 'MU-MIMO HE -LTF Mode' subfield, 'Number Of EHT-LTF Symbols And Midamble Periodicity' subfield, 'UL STBC' subfield, 'LDPC Extra Symbol Segment' subfield, 'AP Tx Power' subfield, 'Pre-FEC Padding' Factor' subfield, 'PE Disambiguity' subfield, 'UL Spatial Reuse' subfield, 'Doppler' subfield, 'HE/EHT P160' subfield, and 'Special User into Field Present' subfield. can be placed in In some embodiments, cross-link related information (CF_CLI) may be disposed in 'Reserved' subfields.

18, one user information field (UIF) includes 'AID12' subfield, 'PHY Version ID' subfield, 'UL Bandwidth Extension' subfield, 'Spatial Reuse 1' subfield, and 'Spatial Reuse 2' subfield. ' subfield, 'U-SIG Disregard And Validat' subfield, 'Reserved' subfield, and 'Trigger Dependent User Info' subfield.

In the 'MU-RTS' format, 'UL Bandwidth Extension' subfield, 'Spatial Reuse 1' subfield, 'Spatial Reuse 2' subfield, and 'U-SIG Disregard And Validat' subfield are not used, and other data are placed. It may be in a reserved state so that it can be.

As an exemplary embodiment, the cross-link related information (IF_CLI) disposed in any one of the individual fields (IF_1 to IF_N) in FIG. 14B includes a 'UL Bandwidth Extension' subfield, a 'Spatial Reuse 1' subfield, ' It may be arranged in at least one of the 'Spatial Reuse 2' subfield and the 'U-SIG Disregard And Validat' subfield. In some embodiments, the cross-link related information (IF_CLI) may be disposed in a 'Reserved' subfield.

19 is a block diagram illustrating a system 1000 according to an exemplary embodiment of the present disclosure. In some embodiments, system 1000 of FIG. 19 may be implemented with at least one chip, and system 1000 implemented with one chip may be referred to as a system-on-chip.

Referring to FIG. 19 , a system 1000 may include an application processor 1010, a memory 1020, an input/output interface 1030, a hardware accelerator 1040, and a communication interface 1050, and the application processor 1010 , The memory 1020, the input/output interface 1030, the hardware accelerator 1040, and the communication interface 1050 may mutually communicate through the bus 1060.

The application processor 1010 may control the system 1000 . For example, the application processor 1010 may include at least one core, and each of the at least one core may execute a series of instructions stored in the memory 1020 . In some embodiments, the application processor 1010 may run an operating system (OS) and run applications on the operating system. The application processor 1010 may control other elements of the system 1000 . For example, the application processor 1010 may instruct the hardware accelerator 1040 to perform a task by providing data, and obtain a result of the task performed by the hardware accelerator 1040 . In addition, the application processor 1010 may provide data to be transmitted to the outside to the communication interface 1050 to instruct transmission, and may obtain data received from the outside through the communication interface 1050 .

Memory 1020 may be accessed by other components via a bus. The memory 1020 may have any structure capable of storing data, and may include, for example, volatile memory such as static random access memory (SRAM) and dynamic random access memory (DRAM), flash memory, and resistive memory (RRAM). It may include non-volatile memory such as random access memory. The memory 1020 may store instructions executed by the application processor 1010 or data read or written by other components.

Input/output interface 1030 may provide an interface for input to and output from system 1000 . For example, the input/output interface 1030 may communicate with an input/output device included in a product together with the system 1000, and may receive user input or provide output to the user through the input/output device. In addition, the input/output interface 1030 may communicate with the system 1000 and peripherals included in the product, and enable the application processor 1010 to control the peripherals.

Hardware accelerator 1040 may be hardware designed to perform functions at high speed. For example, hardware accelerator 1040 may be designed to perform encoding and decoding of data at high speed. Also, the hardware accelerator 1040 may be designed to perform neural processing at high speed. The hardware accelerator 1040 may process data stored in the memory 1020 and store the processed data in the memory 1020 .

Communications interface 1050 may provide a communication channel with objects external to system 1000 . For example, communication interface 1050 may provide a wired communication channel and/or a wireless communication channel. In some embodiments, the communication interface 1050 may perform at least one step included in the wireless communication method using multi-link described above with reference to the drawings. For example, the communication interface 1050 may include at least one processor 1055, and the at least one processor 1055 executes instructions, thereby at least included in the above-described multi-link wireless communication method. You can do one step. In some embodiments, at least one processor 1055 may execute instructions stored in memory 1020 or a memory included in communication interface 1050 . In some embodiments, memory 1020 or memory included in communication interface 1050 may store information gathered about links and may be accessed by at least one processor 1055 .

20 is a diagram illustrating examples of an apparatus for wireless communication according to an exemplary embodiment of the present disclosure. Specifically, FIG. 20 shows an Internet of Things (IoT) network system including a home device 2010, a home appliance 2020, an entertainment device 2030, and an access point 2040.

In some embodiments, in the apparatuses for wireless communication of FIG. 20 , as described above with reference to the drawings, an operation using multi-link may be performed. Accordingly, devices for wireless communication can smoothly perform signaling of the protection mechanism by minimizing interference between links when transmitting and receiving RTS frames and CTS frames in the mutual protection mechanism using multi-links. Accordingly, high reliability of data communication between devices can be guaranteed.

Although the present disclosure has been described with reference to the embodiments shown in the drawings, this is only exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical scope of protection of the present disclosure should be determined by the technical spirit of the appended claims.

Claims (20)

A wireless communication method of a first device with a second device using a plurality of links including first and second links, the method comprising:
entering a transmission preparation period of a first request to send (RTS) frame through the first link;
obtaining transmission-related information of a second RTS frame through the second link;
determining at least one of an additional length of the first RTS frame and cross-link related information based on the transmission related information; and
And determining whether to transmit the second RTS frame based on a result of the determination. According to claim 1,
Determining the additional length of the first RTS frame,
checking transmission timing of the second RTS frame from the transmission-related information;
determining the additional length to match a difference between transmission timing of the first RTS frame and transmission timing of the second RTS frame; and
and filling the first RTS frame with padding data corresponding to the determined additional length. According to claim 1,
Determining the cross-link related information of the first RTS frame,
checking transmission timing of the second RTS frame from the transmission-related information;
determining whether the first link and the second link have a cross-link relationship based on a difference between transmission timing of the first RTS frame and transmission timing of the second RTS frame;
determining the cross-link related information based on the cross-link relationship; and
and filling the first RTS frame with data corresponding to the determined cross-link related information. According to claim 3,
The step of determining whether to transmit the second RTS frame,
and determining to omit transmission of the second RTS frame when the first link and the second link have the cross-link relationship. According to claim 1,
The format of the first RTS frame includes a plurality of fields corresponding to the cross-link related information,
The plurality of fields,
A first field indicating the plurality of links, a second field indicating whether link sensing is required for the plurality of links, and a third field indicating resources allocated to the plurality of links for transmission of CTS frames. A wireless communication method characterized in that. According to claim 5,
The plurality of fields,
and at least one of a fourth field indicating whether the CTS frame can be transmitted through an alternative link for the plurality of links and a padding field filled with padding data whose length is variable according to the additional length. wireless communication method. According to claim 1,
The format of the first RTS frame includes a plurality of individual fields corresponding to the cross-link related information,
Each of the plurality of individual fields,
A first subfield indicating a specific link, a second subfield indicating whether link sensing is necessary for the specific link, and a third subfield indicating resources allocated to the specific link for transmission of a CTS frame. wireless communication method. According to claim 7,
Each of the plurality of individual fields,
and a fourth subfield indicating whether transmission of the CTS frame is possible through an alternative link for the specific link. According to claim 7,
The format of the first RTS frame,
and a padding field in which padding data whose length is variable according to the additional length is disposed. According to claim 1,
The wireless communication method, characterized in that the format of the first RTS frame corresponds to any one of a plurality of trigger frame types in the standard of IEEE 802.11ax. According to claim 10,
The format of the first RTS frame includes a common information field and a user information field,
The wireless communication method, characterized in that the cross-link related information is arranged in any one of the common information field and the user information field. A first device configured to communicate with a second device using a plurality of links comprising first and second links,
a radio frequency (RF) integrated circuit configured to provide access points corresponding to the first and second links, respectively; and
a processor configured to control the access points;
the processor,
In the transmission preparation period of the first RTS frame through the first link,
Obtain transmission-related information of the second RTS frame through a second link, determine at least one of an additional length of the first RTS frame and cross-link related information based on the transmission-related information, and based on the determination result The first device, characterized in that configured to determine whether to transmit the second RTS frame with. According to claim 12,
The format of the first RTS frame includes a plurality of fields corresponding to the cross-link related information,
The plurality of fields,
A first field indicating the plurality of links, a second field indicating whether link sensing is necessary for the plurality of links, a third field indicating resources allocated to the plurality of links for transmission of CTS frames, the plurality of links Characterized in that it further includes at least one of a fourth field indicating whether transmission of the CTS frame is possible through an alternative link for links of and a fifth field filled with padding data whose length is variable according to the additional length. wireless communication device. According to claim 12,
The format of the first RTS frame includes a plurality of individual fields corresponding to the cross-link related information and a padding field filled with padding data whose length is variable according to the additional length,
Each of the plurality of individual fields,
A first subfield indicating a specific link, a second subfield indicating whether link sensing is necessary for the specific link, a third subfield indicating resources allocated to the specific link for transmission of a CTS frame, and a specific link and at least one of a fourth subfield indicating whether transmission of the CTS frame through an alternate link is possible. According to claim 12,
the processor,
The first RTS frame including the cross-link related information is transmitted to the second device through the first link, and transmission of the second RTS frame to the second device through the second link is omitted. A first device characterized in that it controls access points. According to claim 15,
The access points are
The first device, characterized in that configured to receive mutually aligned first and second CTS frames through the first and second links in response to the first RTS frame from the second device. a first device and a second device communicating with each other through a plurality of links;
The first device,
At least one of an additional length of a first RTS frame and cross-link related information among the plurality of RTS frames is determined based on information related to transmission of the plurality of RTS frames through the plurality of links, and based on the determination result, the A wireless communication system, characterized in that configured to generate a first RTS frame and transmit it to the second device through a first link of the plurality of links. According to claim 17,
The first device,
As the first RTS frame including cross-link related information is transmitted, transmission of the second RTS frame among the plurality of RTS frames to the second device through the second link among the plurality of links is omitted. A wireless communication system, characterized in that configured to. According to claim 17,
The second device,
Sensing the second link based on the cross-link related information in response to the first RTS frame, and determining whether to transmit a CTS frame to the first device through the second link based on a sensing result A wireless communication system, characterized in that configured. According to claim 19,
The second device,
When the sensing result indicates that the state of the second link is ready, determine to transmit the CTS frame to the first device through the second link;
When the sensing result indicates that the state of the second link is busy, detect an alternate link among the plurality of links and determine to transmit the CTS frame to the first device through the detected alternate link. A wireless communication system characterized in that.

Images