WO2022164293A1 - 멀티 링크를 사용하는 무선 통신 방법 및 이를 사용하는 무선 통신 단말 - Google Patents
멀티 링크를 사용하는 무선 통신 방법 및 이를 사용하는 무선 통신 단말 Download PDFInfo
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- H04W76/20—Manipulation of established connections
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- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/14—Multichannel or multilink protocols
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- H04W74/0808—Non-scheduled access, e.g. ALOHA using carrier sensing, e.g. carrier sense multiple access [CSMA]
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- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/10—Small scale networks; Flat hierarchical networks
- H04W84/12—WLAN [Wireless Local Area Networks]
Definitions
- the present invention relates to a wireless communication method using a multi-link and a wireless communication terminal using the same.
- Wireless LAN technology is a technology that enables mobile devices such as smart phones, smart pads, laptop computers, portable multimedia players, embedded devices, etc. to be.
- IEEE 802.11b supports a communication speed of up to 11Mbps while using a frequency of the 2.4GHz band.
- IEEE 802.11a commercialized after IEEE 802.11b, uses a frequency of 5 GHz band instead of 2.4 GHz band, thereby reducing the impact on interference compared to the fairly crowded 2.4 GHz band, and using OFDM (orthogonal frequency division multiplexing) technology. The communication speed was improved up to 54 Mbps.
- IEEE 802.11a has a disadvantage in that the communication distance is shorter than that of IEEE 802.11b.
- IEEE 802.11g uses a frequency of the 2.4 GHz band to achieve a communication speed of up to 54 Mbps, and has received considerable attention as it satisfies backward compatibility. have the upper hand
- IEEE 802.11n is a technical standard established to overcome the limit on communication speed, which has been pointed out as a weakness in wireless LAN. IEEE 802.11n aims to increase the speed and reliability of the network and extend the operating distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing rate of up to 540 Mbps or higher, and uses multiple antennas at both ends of the transmitter and receiver to minimize transmission errors and optimize data rates. It is based on MIMO (Multiple Inputs and Multiple Outputs) technology. In addition, this standard may use a coding method that transmits multiple duplicate copies to increase data reliability.
- HT high throughput
- MIMO Multiple Inputs and Multiple Outputs
- IEEE 802.11ac supports a wide bandwidth (80 MHz to 160 MHz) at a frequency of 5 GHz.
- the IEEE 802.11ac standard is defined only in the 5GHz band, but for backward compatibility with existing 2.4GHz band products, the initial 11ac chipsets will also support operation in the 2.4GHz band.
- the wireless LAN speed of multiple stations is at least 1 Gbps, and the maximum single link speed is at least 500 Mbps.
- IEEE 802.11ad is a transmission standard that provides a speed of up to 7 Gbps using beamforming technology, and is suitable for streaming large amounts of data or high bit rate video such as uncompressed HD video.
- the 60 GHz frequency band has a disadvantage in that it is difficult to pass through obstacles and can only be used between devices in a short distance.
- the IEEE 802.11ax High Efficiency WLAN, HEW
- HEW High Efficiency WLAN
- high-frequency-efficiency communication must be provided indoors and outdoors in the presence of high-density stations and access points (APs), and various technologies have been developed to implement this.
- IEEE 802.11be Extremely High Throughput, EHT
- EHT Extremely High Throughput
- An embodiment of the present invention aims to provide a wireless communication method using a multi-link and a wireless communication terminal using the same.
- a multi-link device that does not perform transmission and reception in the second link of the EMLSR link while performing the exchange includes a transceiver; and a processor.
- the EMLSR mode when a first station, which is one of a plurality of stations included in the multi-link device in the first link, performs the frame exchange as a TXOP (transmission opportunity) holder, the processor performs the frame exchange in the second link in the EMLSR mode.
- the TXOP for the frame exchange is terminated before the point in time that is earlier than the point in time when the multi-link device decides to receive the beacon frame.
- the predetermined time may be a delay time for the multi-link device to perform link switching.
- the processor may not transmit a response frame to the initial control frame in order to receive an initial control frame initiating the frame exchange in the first link in the EMLSR mode, and to receive the beacon frame in the second link have.
- the processor is configured for the initial control frame. If, without transmitting a response, the frame exchange initiated by the initial control frame is completed before a time earlier by the predetermined time from the time when the multi-link device receives the beacon frame in the second link, the processor is configured to: A response to the initial control frame may be transmitted.
- the initial control frame may be a multi-user request to send (MU-RTS) frame or a buffer status report poll (BSRP).
- MU-RTS multi-user request to send
- BSRP buffer status report poll
- the beacon frame may be a DTIM beacon.
- the initial control frame may be transmitted at a predetermined data rate using a predetermined format.
- the predetermined time may be signaled by the multi-link device.
- the processor signals a minimum duration of padding of an initial control frame required for the link switching, the initial control frame initiates frame exchange in the EMLSR link in the EMLSR mode, and the initial control frame includes the padding It may include padding corresponding to a time equal to or longer than the minimum length of .
- the EMLSR mode may be applied only to some of the plurality of links in which a plurality of stations included in the multi-link device operate.
- a frame exchange in a first link of an EMLSR link including a plurality of stations operating in a plurality of links, but a plurality of links to which the EMLSR mode is applied in an enhanced multi-link single radio (EMLSR) mode
- An access point communicating with a multi-link device that does not perform transmission and reception in the second link of the EMLSR link while performing the EMLSR includes a transceiver; and a processor.
- the processor transmits an initial control frame for starting the frame exchange on the first link in the EMLSR mode, and a time point earlier than a time point at which the multi-link device decides to receive a beacon frame on the second link by a predetermined time Ends the TXOP for the frame exchange before.
- the predetermined time is a delay time for the multi-link device to perform link switching.
- the initial control frame may be a multi-user request to send (MU-RTS) frame or a buffer status report poll (BSRP).
- MU-RTS multi-user request to send
- BSRP buffer status report poll
- the beacon frame may be a DTIM beacon.
- the processor may transmit the initial control frame at a predetermined data rate using a predetermined format.
- the predetermined time may be signaled by the multi-link device.
- the processor receives a minimum duration of padding of an initial control frame required for link switching from the multi-link device, and includes a padding corresponding to a time equal to or longer than the minimum length of the padding in the initial control frame.
- the EMLSR mode may be applied only to some of the plurality of links in which a plurality of stations included in the multi-link device operate.
- the EMLSR link includes a plurality of stations each operating in a plurality of links, but during frame exchange in the first link of the EMLSR link, which is a plurality of links to which the EMLSR mode is applied in an enhanced multi-link single radio (EMLSR) mode.
- EMLSR enhanced multi-link single radio
- the method of operation includes receiving an initial control frame initiating the frame exchange on the first link in the EMLSR mode; and not transmitting a response frame to the initial control frame in order to receive the beacon frame in the second link.
- the step of not transmitting a response frame to the initial control frame in order to receive the beacon frame in the second link may include: when the frame exchange initiated by the initial control frame is initiated by the multi-link device in the second link, the beacon frame If it is not completed before the time earlier than the predetermined time from the time of receiving
- the method may include transmitting a response to the initial control frame when the device is completed before a time earlier by the predetermined time from the point in time when the beacon frame is received.
- the initial control frame may be a multi-user request to send (MU-RTS) frame or a buffer status report poll (BSRP).
- MU-RTS multi-user request to send
- BSRP buffer status report poll
- An embodiment of the present invention provides a wireless communication method efficiently using a multi-link and a wireless communication terminal using the same.
- FIG. 1 shows a wireless LAN system according to an embodiment of the present invention.
- FIG. 2 shows a wireless LAN system according to another embodiment of the present invention.
- FIG 3 shows the configuration of a station according to an embodiment of the present invention.
- FIG 4 shows the configuration of an access point according to an embodiment of the present invention.
- FIG. 5 schematically shows a process in which a station establishes a link with an access point.
- FIG. 6 illustrates an example of a carrier sense multiple access (CSMA)/collision avoidance (CA) method used in wireless LAN communication.
- CSMA carrier sense multiple access
- CA collision avoidance
- FIG. 7 illustrates an example of various standard generation-specific PPDU (Physical Layer Protocol Data Unit) formats.
- PPDU Physical Layer Protocol Data Unit
- EHT Extremely High Throughput
- PPDU Physical Layer Protocol Data Unit
- FIG. 9 shows a multi-link device according to an embodiment of the present invention.
- FIG. 10 shows that transmission of different links is simultaneously performed in a multi-link operation according to an embodiment of the present invention.
- FIG 11 shows an operation of a multi-link device when a link is changed according to an embodiment of the present invention.
- FIG 13 shows an operation of releasing the channel access prohibition when it is confirmed that the intended recipient of the PPDU received by the station of the non-STR multi-link device is not the station according to an embodiment of the present invention.
- 15 shows an operation in which a station performs transmission after releasing the channel access prohibition according to an embodiment of the present invention.
- 16 shows transmission performed based on the state of a station in a non-STR multi-link device according to an embodiment of the present invention.
- FIG. 18 shows an operation in which an STR multi-link device stops transmission to a non-STR multi-link device according to an embodiment of the present invention.
- FIG. 19 shows that the STR multi-link device processes a CW value when recognizing a transmission collision between links according to an embodiment of the present invention.
- FIG. 20 shows an operation in which an STR multi-link device performs channel access again after stopping transmission to a non-STR multi-link device according to an embodiment of the present invention.
- 21 shows an operation in which the STR multi-link device transmits a CTS-to-Self frame before transmission to the non-STR multi-link device according to an embodiment of the present invention.
- FIG. 22 shows that a plurality of APs included in an STR multi-link device perform transmission to a plurality of stations included in one non-STR multi-link device according to an embodiment of the present invention.
- FIG. 23 shows that a plurality of APs included in an STR multi-link device perform a plurality of transmissions in which the termination of transmission is synchronized to a plurality of stations included in one non-STR multi-link device according to an embodiment of the present invention.
- FIG. 24 shows that a multi-link device exchanges RTS/CTS frames according to an embodiment of the present invention.
- FIG. 25 shows a hidden node problem occurring in the RTS/CTS frame exchange procedure according to the embodiment described with reference to FIG. 24 .
- 26 shows that a multi-link device exchanges RTS/CTS frames according to an embodiment of the present invention.
- FIG. 27 shows that a multi-link device transmits a response to a control frame exceptionally even when channel access is prohibited according to a temporary example of the present invention.
- 29 shows that a control frame is transmitted through a link in which a station in which channel access is not prohibited operates, rather than a link in which a station in which channel access is prohibited, operates according to an embodiment of the present invention.
- FIG. 30 shows that a multi-link device transmits an ACK according to an embodiment of the present invention.
- 31 shows an element field indicating information on sync PPDU reception support or transmission support according to an embodiment of the present invention.
- 35 shows a connection between a single radio multi-link device and an AP multi-link device according to an embodiment of the present invention.
- FIG. 37 shows an operation of a single radio multi-link device performing channel access in consideration of a delay time of a radio frequency (RF) chain change according to an embodiment of the present invention.
- RF radio frequency
- FIG. 40 shows that a station and a single radio multi-link device perform an NDP sounding process according to an embodiment of the present invention.
- 41 shows that a station and a single radio multi-link device perform a feedback beamforming sounding sequence according to an embodiment of the present invention.
- the multi-link device transmits traffic mapped to each station of the multi-link device according to an embodiment of the present invention.
- 50 shows a Multi-Link element signaling information about a length of padding of an initial control frame according to an embodiment of the present invention.
- the multi-link device terminates TXOP in a link in which frame exchange is performed in EMLSR mode in consideration of a DTIM beacon received in an EMLSR link in which frame exchange is not performed in EMLSR mode.
- a field and a subfield may be used interchangeably.
- FIG. 1 shows a wireless LAN system according to an embodiment of the present invention.
- the WLAN system includes one or more basic service sets (BSS), which indicate a set of devices that can communicate with each other by successfully synchronizing.
- BSS basic service sets
- the BSS may be divided into an infrastructure BSS (infrastructure BSS) and an independent BSS (IBSS), and FIG. 1 shows the infrastructure BSS among them.
- infrastructure BSS infrastructure BSS
- IBSS independent BSS
- the infrastructure BSS (BSS1, BSS2) includes one or more stations (STA1, STA2, STA3, STA4, STA5), an access point (AP-1), which is a station providing a distribution service. , AP-2), and a distribution system (DS) for connecting a plurality of access points (AP-1, AP-2).
- BSS1, BSS2 includes one or more stations (STA1, STA2, STA3, STA4, STA5), an access point (AP-1), which is a station providing a distribution service. , AP-2), and a distribution system (DS) for connecting a plurality of access points (AP-1, AP-2).
- a station is an arbitrary device that includes a medium access control (MAC) and a physical layer interface for a wireless medium that conforms to the provisions of the IEEE 802.11 standard, and in a broad sense, a non-access point ( It includes both non-AP stations as well as access points (APs). Also, in this specification, the term 'terminal' may be used to refer to a non-AP STA, an AP, or both.
- the station for wireless communication includes a processor and a communication unit, and may further include a user interface unit and a display unit according to an embodiment.
- the processor may generate a frame to be transmitted through the wireless network or process a frame received through the wireless network, and may perform various other processes for controlling the station.
- the communication unit is functionally connected to the processor and transmits and receives frames through a wireless network for the station.
- a terminal may be used as a term including a user equipment (UE).
- An access point is an entity that provides access to a distribution system (DS) via a wireless medium for a station associated with it.
- DS distribution system
- the AP is used as a concept including a PCP (Personal BSS Coordination Point), and broadly, a centralized controller, a base station (BS), a Node-B, a BTS (Base Transceiver System), or a site. It may include all concepts such as a controller.
- the AP may also be referred to as a base wireless communication terminal
- the base wireless communication terminal is a term including all of an AP, a base station, an eNB (eNodeB), and a transmission point (TP) in a broad sense.
- the base wireless communication terminal may include various types of wireless communication terminals for allocating communication medium resources and performing scheduling in communication with a plurality of wireless communication terminals.
- a plurality of infrastructure BSSs may be interconnected through a distribution system (DS).
- DS distribution system
- ESSs extended service sets
- FIG. 2 illustrates an independent BSS as a wireless LAN system according to another embodiment of the present invention.
- the same or corresponding parts to the embodiment of Fig. 1 will be omitted redundant description.
- BSS3 shown in FIG. 2 is an independent BSS and does not include an AP, all stations STA6 and STA7 are not connected to the AP.
- the independent BSS is not allowed to access the distribution system and forms a self-contained network.
- each of the stations STA6 and STA7 may be directly connected to each other.
- the station 100 may include a processor 110 , a communication unit 120 , a user interface unit 140 , a display unit 150 , and a memory 160 .
- the communication unit 120 transmits and receives wireless signals such as wireless LAN packets, and may be built-in to the station 100 or provided externally.
- the communication unit 120 may include at least one communication module using different frequency bands.
- the communication unit 120 may include communication modules of different frequency bands such as 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz.
- the station 100 may include a communication module using a frequency band of 7.125 GHz or higher and a communication module using a frequency band of 7.125 GHz or lower.
- Each communication module may perform wireless communication with an AP or an external station according to a wireless LAN standard of a frequency band supported by the corresponding communication module.
- the communication unit 120 may operate only one communication module at a time or a plurality of communication modules simultaneously according to the performance and requirements of the station 100 .
- each communication module may be provided in an independent form, or a plurality of modules may be integrated into one chip.
- the communication unit 120 may represent an RF communication module that processes a radio frequency (RF) signal.
- RF radio frequency
- the user interface unit 140 includes various types of input/output means provided in the station 100 . That is, the user interface unit 140 may receive a user input using various input means, and the processor 110 may control the station 100 based on the received user input. Also, the user interface unit 140 may perform an output based on a command of the processor 110 using various output means.
- the display unit 150 outputs an image on the display screen.
- the display unit 150 may output various display objects such as content executed by the processor 110 or a user interface based on a control command of the processor 110 .
- the memory 160 stores a control program used in the station 100 and various data corresponding thereto.
- a control program may include an access program necessary for the station 100 to access an AP or an external station.
- the processor 110 of the present invention may execute various commands or programs and process data inside the station 100 .
- the processor 110 may control each unit of the above-described station 100 , and may control data transmission/reception between the units.
- the processor 110 may execute a program for accessing the AP stored in the memory 160 and receive a communication setting message transmitted by the AP.
- the processor 110 may read information on the priority condition of the station 100 included in the communication setup message, and request access to the AP based on the information on the priority condition of the station 100 .
- the processor 110 of the present invention may refer to the main control unit of the station 100, and may refer to a control unit for individually controlling some components of the station 100, such as the communication unit 120, according to an embodiment.
- the processor 110 may be a modem or a modulator and/or demodulator that modulates and demodulates a radio signal transmitted and received from the communication unit 120 .
- the processor 110 controls various operations of wireless signal transmission and reception of the station 100 according to an embodiment of the present invention. Specific examples thereof will be described later.
- the station 100 shown in FIG. 3 is a block diagram according to an embodiment of the present invention, and the separated blocks are logically divided into device elements. Accordingly, the elements of the above-described device may be mounted as one chip or a plurality of chips according to the design of the device. For example, the processor 110 and the communication unit 120 may be integrated into one chip or implemented as a separate chip. In addition, in the embodiment of the present invention, some components of the station 100 , such as the user interface unit 140 and the display unit 150 , may be selectively provided in the station 100 .
- the AP 200 may include a processor 210 , a communication unit 220 , and a memory 260 .
- the AP 200 in FIG. 4 redundant descriptions of parts identical to or corresponding to those of the station 100 of FIG. 3 will be omitted.
- the AP 200 includes a communication unit 220 for operating the BSS in at least one frequency band.
- the communication unit 220 of the AP 200 may also include a plurality of communication modules using different frequency bands. That is, the AP 200 according to an embodiment of the present invention may include two or more communication modules in different frequency bands, for example, 2.4 GHz, 5 GHz, 6 GHz, and 60 GHz.
- the AP 200 may include a communication module using a frequency band of 7.125 GHz or higher and a communication module using a frequency band of 7.125 GHz or lower.
- Each communication module may perform wireless communication with a station according to a wireless LAN standard of a frequency band supported by the corresponding communication module.
- the communication unit 220 may operate only one communication module at a time or a plurality of communication modules simultaneously according to the performance and requirements of the AP 200 .
- the communication unit 220 may represent an RF communication module that processes a radio frequency (RF) signal.
- RF radio frequency
- the memory 260 stores a control program used in the AP 200 and various data corresponding thereto.
- the control program may include an access program for managing access of stations.
- the processor 210 may control each unit of the AP 200 , and may control data transmission/reception between the units.
- the processor 210 may execute a program for connection with a station stored in the memory 260 and transmit a communication setting message for one or more stations.
- the communication setting message may include information on the access priority condition of each station.
- the processor 210 performs connection establishment according to the connection request of the station.
- the processor 210 may be a modem or a modulator and/or demodulator that modulates and demodulates a radio signal transmitted and received from the communication unit 220 .
- the processor 210 controls various operations of wireless signal transmission and reception of the AP 200 according to an embodiment of the present invention. Specific examples thereof will be described later.
- FIG. 5 schematically shows a process in which a station establishes a link with an access point.
- the scanning step is a step in which the STA 100 acquires access information of the BSS operated by the AP 200 .
- a passive scanning method in which information is obtained by using only a beacon message S101 periodically transmitted by the AP 200, and a probe request by the STA 100 to the AP
- an active scanning method for transmitting a probe request (S103) and receiving a probe response from the AP (S105) to obtain access information.
- the STA 100 successfully receiving the radio access information in the scanning step transmits an authentication request (S107a), receives an authentication response from the AP 200 (S107b), and performs the authentication step do.
- the STA 100 transmits an association request (S109a), receives an association response from the AP 200 (S109b), and performs the association step.
- association basically means wireless coupling, but the present invention is not limited thereto, and coupling in a broad sense may include both wireless coupling and wired coupling.
- the authentication server 300 is a server that processes 802.1X-based authentication with the STA 100 , and may exist physically coupled to the AP 200 or exist as a separate server.
- FIG. 6 illustrates an example of a carrier sense multiple access (CSMA)/collision avoidance (CA) method used in wireless LAN communication.
- CSMA carrier sense multiple access
- CA collision avoidance
- a terminal performing wireless LAN communication checks whether a channel is busy by performing carrier sensing before transmitting data. If a radio signal of a predetermined strength or higher is detected, it is determined that the corresponding channel is busy, and the terminal delays access to the corresponding channel. This process is called clear channel assessment (CCA), and the level at which the corresponding signal is detected is called a CCA threshold. If a radio signal greater than or equal to the CCA threshold received by the terminal has the corresponding terminal as a receiver, the terminal processes the received radio signal. On the other hand, when no radio signal is detected in the corresponding channel or when a radio signal having an intensity smaller than the CCA threshold is detected, the channel is determined to be in an idle state.
- CCA clear channel assessment
- each terminal having data to transmit performs a backoff procedure after a time of Inter Frame Space (IFS), such as AIFS (Arbitration IFS), PIFS (PCF IFS), etc. according to the situation of each terminal. do.
- IFS Inter Frame Space
- the AIFS may be used as a configuration to replace the existing DIFS (DCF IFS).
- DCF IFS DIFS
- Each terminal waits while decreasing the slot time as much as a random number determined for the corresponding terminal during the interval of the idle state of the channel, and the terminal that has exhausted the slot time attempts access to the corresponding channel do. In this way, a period in which each terminal performs a backoff procedure is called a contention window period.
- the random number may be referred to as a backoff counter. That is, the initial value of the backoff counter is set by an integer that is a random number obtained by the terminal.
- the UE may decrement the backoff counter by 1.
- the terminal may be allowed to perform channel access on the corresponding channel. Therefore, when the channel is idle during the AIFS time and the slot time of the backoff counter, the transmission of the terminal may be allowed.
- the corresponding terminal may transmit data through the channel.
- the collided terminals receive a new random number and perform the backoff procedure again.
- the random number newly allocated to each terminal may be determined within a range (2*CW) twice the range of random numbers previously allocated to the corresponding terminal (contention window, CW).
- each terminal attempts to access by performing the backoff procedure again in the next contention window period, and at this time, each terminal performs the backoff procedure from the remaining slot time in the previous contention window period. In this way, each terminal performing wireless LAN communication can avoid collision with each other for a specific channel.
- FIG. 7 illustrates an example of various standard generation-specific PPDU (Physical Layer Protocol Data Unit) formats. More specifically, FIG. 7(a) shows an embodiment of a legacy PPDU format based on 802.11a/g, FIG. 7(b) shows an embodiment of an HE PPDU format based on 802.11ax, and FIG. 7(c) shows an embodiment of a non-legacy PPDU (ie, EHT PPDU) format based on 802.11be. Also, FIG. 7(d) shows the detailed field configuration of L-SIG and RL-SIG commonly used in the PPDU formats.
- PPDU Physical Layer Protocol Data Unit
- the preamble of the legacy PPDU includes a legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal field (L-SIG).
- L-STF legacy short training field
- L-LTF legacy long training field
- L-SIG legacy signal field
- the L-STF, L-LTF, and L-SIG may be referred to as a legacy preamble.
- the preamble of the HE PPDU includes a Repeated Legacy Short Training field (RL-SIG), a High Efficiency Signal A field (HE-SIG-A), and a High Efficiency Signal (HE-SIG-B) in the legacy preamble.
- B field a High Efficiency Short Training field (HE-STF), and a High Efficiency Long Training field (HE-LTF) are additionally included.
- the RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF and HE-LTF may be referred to as a HE preamble.
- a specific configuration of the HE preamble may be modified according to the HE PPDU format. For example, HE-SIG-B may be used only in the HE MU PPDU format.
- the preamble of the EHT PPDU is a Repeated Legacy Short Training field (RL-SIG), a Universal Signal field (U-SIG), and an Extremely High Throughput Signal A field (EHT-SIG-A) in the legacy preamble.
- EHT-SIG-A Extremely High Throughput Signal B field
- EHT-STF Extremely High Throughput Short Training field
- EHT-LTF Extremely High Throughput Long Training field
- the RL-SIG, EHT-SIG-A, EHT-SIG-B, EHT-STF and EHT-LTF may be referred to as an EHT preamble.
- the specific configuration of the non-legacy preamble may be modified according to the EHT PPDU format. For example, EHT-SIG-A and EHT-SIG-B may be used only in some of the EHT PPDU formats.
- the L-SIG includes an L_RATE field and an L_LENGTH field.
- the L_RATE field consists of 4 bits and indicates an MCS used for data transmission.
- the L_RATE field is a 6/9/12/18/24/ combination of modulation methods such as BPSK/QPSK/16-QAM/64-QAM and inefficiencies such as 1/2, 2/3, and 3/4. Indicates a value of one of the transmission rates of 36/48/54 Mbps.
- the L_RATE field is set to the minimum rate of 6 Mbps.
- the legacy terminal and the non-legacy terminal may interpret the L_LENGTH field in different ways.
- a method for a legacy terminal or a non-legacy terminal to interpret the length of the corresponding PPDU by using the L_LENGTH field is as follows.
- 3 bytes ie, 24 bits
- 4us which is one symbol duration of 64FFT.
- the number of 64FFT reference symbols after L-SIG is obtained.
- the length of the corresponding PPDU that is, the reception time (RXTIME)
- RXTIME reception time
- the length of the PPDU may be set to a maximum of 5.484 ms.
- the non-legacy terminal transmitting the corresponding PPDU should set the L_LENGTH field as shown in Equation 2 below.
- TXTIME is the total transmission time constituting the corresponding PPDU, as shown in Equation 3 below.
- TX represents the transmission time of X.
- the U-SIG Universal SIG
- the U-SIG is a 64FFT-based OFDM 2 symbol and can transmit a total of 52 bits of information. Among them, 43 bits excluding CRC/Tail 9 bits are largely divided into a VI (Version Independent) field and a VD (Version Dependent) field.
- the VI bit maintains the current bit configuration in the future so that even if a PPDU of a subsequent generation is defined, the current 11be UEs can obtain information about the corresponding PPDU through the VI fields of the corresponding PPDU.
- the VI field consists of PHY version, UL/DL, BSS Color, TXOP, and Reserved fields.
- the PHY version field is 3 bits and serves to sequentially classify 11be and subsequent generation WLAN standards into versions. 11be has a value of 000b.
- the UL/DL field identifies whether the corresponding PPDU is an uplink/downlink PPDU.
- BSS Color means an identifier for each BSS defined in 11ax, and has a value of 6 bits or more.
- TXOP means the Transmit Opportunity Duration delivered in the MAC header. By adding it to the PHY header, the length of the TXOP including the corresponding PPDU can be inferred without the need to decode the MPDU, and has a value of 7 bits or more.
- the VD field is signaling information useful only for the 11be version of the PPDU, and may be composed of a field commonly used for any PPDU format, such as a PPDU format and BW, and a field defined differently for each PPDU format.
- the PPDU format is a delimiter that distinguishes EHT SU (Single User), EHT MU (Multiple User), EHT TB (Trigger-based), and EHT ER (Extended Range) PPDUs.
- BW basic PPDU BW options of 20, 40, 80, 160 (80+80), 320 (160+160) MHz (BW that can be expressed in the form of an exponential power of 20*2 can be called basic BW) ) and various remaining PPDU BWs configured through Preamble Puncturing.
- basic BW basic PPDU BW
- 80 MHz may be signaled in a punctured form.
- the punctured and modified channel shape may be signaled directly in the BW field, or may be signaled using the BW field and a field appearing after the BW field (eg, a field in the EHT-SIG field).
- the puncturing mode can signal up to 3 only. If the BW field is 4 bits, since a total of 16 BW signaling is possible, the puncturing mode can signal a maximum of 11.
- the field located after the BW field varies depending on the type and format of the PPDU, the MU PPDU and the SU PPDU can be signaled in the same PPDU format, and a field for distinguishing the MU PPDU and the SU PPDU is located before the EHT-SIG field. and additional signaling for this may be performed.
- both the SU PPDU and the MU PPDU include the EHT-SIG field
- some fields not required in the SU PPDU may be compressed.
- the information on the field to which compression is applied may be omitted or may have a size reduced from the size of the original field included in the MU PPDU.
- the common field of the EHT-SIG may be omitted or replaced, or a user-specific field may be replaced or reduced to one, etc. may have a different configuration.
- the SU PPDU may further include a compression field indicating whether compression is performed, and some fields (eg, RA field, etc.) may be omitted according to a value of the compression field.
- some fields eg, RA field, etc.
- the EHT-SIG field When a part of the EHT-SIG field of the SU PPDU is compressed, information to be included in the compressed field may be signaled together in an uncompressed field (eg, a common field, etc.). Since the MU PPDU is a PPDU format for simultaneous reception by multiple users, the EHT-SIG field must be transmitted after the U-SIG field, and the amount of signaled information may be variable. That is, since a plurality of MU PPDUs are transmitted to a plurality of STAs, each STA must recognize the location of the RU to which the MU PPDU is transmitted, the STA to which each RU is allocated, and whether the transmitted MU PPDU is transmitted to itself.
- an uncompressed field eg, a common field, etc.
- the AP must transmit the above information in the EHT-SIG field.
- the U-SIG field signals information for efficiently transmitting the EHT-SIG field, which may be the number of symbols and/or the modulation method of the EHT-SIG field, MCS.
- the EHT-SIG field may include size and location information of an RU allocated to each user.
- a plurality of RUs may be allocated to an STA, and the plurality of RUs may or may not be consecutive. If the RUs allocated to the STA are not consecutive, the STA must recognize the RU punctured in the middle to efficiently receive the SU PPDU. Accordingly, the AP may transmit information on punctured RUs (eg, puncturing patterns of RUs, etc.) among RUs allocated to the STA in the SU PPDU.
- punctured RUs eg, puncturing patterns of RUs, etc.
- a puncturing mode field including information indicating whether a puncturing mode is applied and a puncturing pattern in a bitmap format may be included in the EHT-SIG field, and the puncturing mode field may appear within the bandwidth.
- the form of a discontinuous channel may be signaled.
- the type of the signaled discontinuous channel is limited, and it indicates the BW and discontinuous channel information of the SU PPDU in combination with the value of the BW field.
- the STA can recognize the bandwidth allocated to it through the BW field included in the PPDU, and the U-SIG field or EHT-SIG field included in the PPDU.
- a punctured resource among the allocated bandwidth can be recognized through the puncturing mode field of .
- the terminal may receive the PPDU in the remaining resource units except for the specific channel of the punctured resource unit.
- the plurality of RUs allocated to the STA may be configured with different frequency bands or tones.
- the reason why only the limited type of discontinuous channel type is signaled is to reduce the signaling overhead of the SU PPDU. Since puncturing can be performed for each 20 MHz subchannel, if puncturing is performed on a BW having a large number of 20 MHz subchannels such as 80, 160, 320 MHz, in the case of 320 MHz, the remaining 20 MHz subchannels except for the primary channel.
- the type of discontinuous channel (when only the edge 20 MHz punctured type is viewed as discontinuous) must be signaled by expressing whether or not 15 are used. As such, allocating 15 bits for signaling the discontinuous channel type of single-user transmission may act as an excessively large signaling overhead in consideration of the low transmission rate of the signaling part.
- the present invention proposes a technique for signaling the discontinuous channel type of the SU PPDU, and shows the discontinuous channel type determined according to the proposed technique.
- a scheme for signaling primary 160 MHz and secondary 160 MHz puncturing types is proposed.
- an embodiment of the present invention proposes a scheme for differentiating the configuration of the PPDU indicated by the preamble puncturing BW values according to the PPDU format signaled in the PPDU Format field. It is assumed that the length of the BW field is 4 bits, and in case of EHT SU PPDU or TB PPDU, EHT-SIG-A of 1 symbol is additionally signaled after U-SIG or EHT-SIG-A is not signaled at all. Therefore, in consideration of this, it is necessary to completely signal up to 11 puncturing modes through only the BW field of the U-SIG.
- the BW field may be set to 1 bit to signal whether the PPDU uses a 20 MHz or 10 MHz band.
- SIG-B which is a signaling field for simultaneous reception by multiple users, is essential, and SIG-B may be transmitted without a separate SIG-A after the U-SIG.
- U-SIG needs to signal information for decoding SIG-B.
- SIG-B MCS SIG-B MCS
- SIG-B DCM Number of SIG-B Symbols
- SIG-B Compression Number of EHT-LTF Symbols fields.
- EHT Extremely High Throughput
- PPDU Physical Layer Protocol Data Unit
- the PPDU may be composed of a preamble and a data part, and the format of one type of EHT PPDU may be distinguished according to the U-SIG field included in the preamble. Specifically, based on the PPDU format field included in the U-SIG field, whether the format of the PPDU is an EHT PPDU may be indicated.
- the EHT SU PPDU is a PPDU used for single user (SU) transmission between the AP and a single STA, and an EHT-SIG-A field for additional signaling may be located after the U-SIG field.
- SU single user
- EHT Trigger-based PPDU format that is an EHT PPDU transmitted based on a trigger frame.
- the EHT Trigger-based PPDU is an EHT PPDU transmitted based on the trigger frame, and is an uplink PPDU used for a response to the trigger frame.
- the EHT-SIG-A field is not located after the U-SIG field.
- the EHT MU PPDU is a PPDU used to transmit a PPDU to one or more STAs.
- the HE-SIG-B field may be located after the U-SIG field.
- FIG. 8(d) shows an example of an EHT ER SU PPDU format used for single-user transmission with an STA in an extended range.
- the EHT ER SU PPDU may be used for single-user transmission with an STA of a wider range than the EHT SU PPDU described in FIG. 8A , and the U-SIG field may be repeatedly located on the time axis.
- the EHT MU PPDU described in (c) of FIG. 8 may be used by the AP for downlink transmission to a plurality of STAs.
- the EHT MU PPDU may include scheduling information so that a plurality of STAs can simultaneously receive the PPDU transmitted from the AP.
- the EHT MU PPDU may deliver AID information of the receiver and/or the sender of the PPDU transmitted through the user specific field of the EHT-SIG-B to the STA. Accordingly, the plurality of terminals receiving the EHT MU PPDU may perform a spatial reuse operation based on the AID information of the user-specific field included in the preamble of the received PPDU.
- the resource unit allocation (RA) field of the HE-SIG-B field included in the HE MU PPDU is the configuration of the resource unit in a specific bandwidth (eg, 20 MHz, etc.) of the frequency axis (eg, , the partition type of the resource unit). That is, the RA field may indicate the configuration of resource units divided in the bandwidth for transmission of the HE MU PPDU in order for the STA to receive the PPDU.
- Information on the STA allocated (or designated) to each divided resource unit may be included in the user-specific field of the EHT-SIG-B and transmitted to the STA. That is, the user specific field may include one or more user fields corresponding to each divided resource unit.
- a user field corresponding to at least one resource unit used for data transmission among a plurality of divided resource units may include an AID of a receiver or a sender, and the remaining resource units not performed for data transmission ( )), the user field may include a preset null STA ID.
- a frame or a MAC frame may be used interchangeably with an MPDU.
- the link is a physical path, and may be configured as one wireless medium that can be used to transmit a MAC service data unit (MSDU).
- MSDU MAC service data unit
- the wireless communication device can continue to communicate through the other link. In this way, the wireless communication device can effectively use a plurality of channels.
- the wireless communication device simultaneously performs communication using a plurality of links, overall throughput may be increased.
- a wireless communication method of a wireless communication device using a plurality of links will be described with reference to FIGS. 9 to 26 . First, a specific form of a wireless communication device using a plurality of links will be described with reference to FIG. 9 .
- FIG. 9 shows a multi-link device according to an embodiment of the present invention.
- a multi-link device may refer to a device having one or more affiliated stations.
- a multi-link device may indicate a device having two or more associated stations.
- the multi-link device can exchange multi-link elements.
- the multi-link element includes information about one or more stations or one or more links.
- the multi-link element may include a multi-link setup element, which will be described later.
- the multi-link device may be a logical entity.
- a multi-link device may have a plurality of associated stations.
- the multi-link device may be referred to as a multi-link logical entity (MLLE) or a multi-link entity (MLE).
- MLE multi-link logical entity
- a multi-link device may have one MAC service access point (medium access control service access point, SAP) up to a logical link control (LLC).
- SAP medium access control service access point
- LLC logical link control
- the MLD may have one MAC data service.
- a plurality of stations included in a multi-link device may operate on a plurality of links. Also, a plurality of stations included in the multi-link device may operate on a plurality of channels. Specifically, a plurality of stations included in the multi-link device may operate on a plurality of different links or a plurality of different channels. For example, a plurality of stations included in the multi-link device may operate in a plurality of different channels of 2.4 GHz, 5 GHz, and 6 GHz.
- the operation of the multi-link device may be referred to as a multi-link operation, an MLD operation, or a multi-band operation.
- the multi-link device when the station affiliated with the far link device is an AP, the multi-link device may be referred to as an AP MLD. Also, when the station affiliated with the far link device is a non-AP station, the multi-link device may be referred to as a non-AP MLD.
- the AP MLD includes a first AP (AP1), a second AP (AP2), and a third AP (AP3).
- the non-AP MLD includes a first non-AP STA (non-AP STA1), a second non-AP STA (non-AP STA2), and a third non-AP STA (non-AP STA3).
- the first AP (AP1) and the first non-AP STA (non-AP STA1) communicate through a first link (Link1).
- the second AP (AP2) and the second non-AP STA (non-AP STA2) communicate through a second link (Link2).
- the third AP (AP3) and the third non-AP STA (non-AP STA3) communicate through a third link (Link3).
- the multi-link operation may include a multi-link setup operation.
- the multi-link configuration corresponds to the above-described association operation of the single-link operation, and may need to be preceded for frame exchange in the multi-link.
- the multi-link device may obtain information necessary for multi-link setup from the multi-link setup element.
- the multi-link setup element may include multi-link related capability information.
- the capability information may include information indicating whether any one of a plurality of devices included in the multi-link device can transmit and the other device can simultaneously perform reception.
- the capability information may include information about a link that can be used by each station included in the MLD.
- the capability information may include information about a channel that can be used by each station included in the MLD.
- Multi-link establishment may be established through negotiation between peer stations. Specifically, multi-link setup may be performed through communication between stations without communication with the AP. In addition, the multi-link setting may be set through any one link. For example, even when the first to third links are configured through the multi-link, the multi-link setup may be performed through the first link.
- a mapping between a traffic identifier (TID) and a link may be established. Specifically, a frame corresponding to a TID of a specific value can be exchanged only through a predetermined link.
- the mapping between the TID and the link may be set to be directional-based. For example, when a plurality of links are established between the first multi-link device and the second multi-link device, the first multi-link device is configured to transmit the frame of the first TID to the plurality of links, the first link, and the second multi-link device The device may be configured to transmit the frame of the second TID on the first link.
- there may be a default setting in the mapping between the TID and the link Specifically, when there is no additional configuration in the multi-link configuration, the multi-link device may exchange frames corresponding to the TID in each link according to the default configuration. In this case, the basic setting may be that all TIDs are exchanged in any one link.
- TID is an ID that classifies traffic and data to support quality of service (QoS).
- QoS quality of service
- the TID may be used or allocated in a layer higher than the MAC layer.
- the TID may indicate a traffic category (TC) and a traffic stream (TS).
- TC traffic category
- TS traffic stream
- 16 TIDs can be distinguished.
- the TID may be designated as any one of 0 to 15.
- a TID value used may be differently designated according to an access policy, channel access, or medium access method. For example, when enhanced distributed channel access (EDCA) or hybrid coordination function contention based channel access (HCAF) is used, the value of the TID may be assigned from 0 to 7.
- EDCA enhanced distributed channel access
- HCAF hybrid coordination function contention based channel access
- the TID may indicate user priority (UP).
- UP may be designated according to TC or TS. UP may be allocated in a layer higher than MAC.
- HCCA HCF controlled channel access
- SPCA SPCA
- the value of TID may be assigned from 8 to 15.
- the TID may indicate the TSID.
- HEMM or SEMM the value of TID may be assigned from 8 to 15.
- the TID may indicate the TSID.
- AC may be a label for providing QoS in EDCA.
- AC may be a label for indicating the EDCA parameter set.
- the EDCA parameter or EDCA parameter set is a parameter used in channel contention of EDCA.
- QoS stations can use AC to guarantee QoS.
- AC may include AC_BK, AC_BE, AC_VI, and AC_VO.
- Each of AC_BK, AC_BE, AC_VI, and AC_VO may represent a background, a best effort, a video, and a voice.
- AC_BK, AC_BE, AC_VI, and AC_VO may be classified into lower ACs.
- AC_VI may be subdivided into AC_VI primary and AC_VI alternate.
- AC_VO may be subdivided into AC_VO primary and AC_VO alternate.
- UP or TID may be mapped to AC.
- each of 1, 2, 0, 3, 4, 5, 6, and 7 of the UP or TID may be mapped to each of AC_BK, AC_BK, AC_BE, AC_BE, AC_VI, AC_VI, AC_VO, and AC_VO.
- each of 1, 2, 0, 3, 4, 5, 6, and 7 of the UP or TID may be mapped to AC_BK, AC_BK, AC_BE, AC_BE, AC_VI alternate, AC_VI primary, AC_VO primary, and AC_VO alternate, respectively.
- 1, 2, 0, 3, 4, 5, 6, and 7 of the UP or TID may be sequentially high in priority.
- page 1 may have a low priority
- page 7 may have a high priority. Therefore, the priority may be increased in the order of AC_BK, AC_BE, AC_VI, and AC_VO.
- each of AC_BK, AC_BE, AC_VI, and AC_VO may correspond to ACI (AC index) 0, 1, 2, and 3, respectively.
- the mapping between TIDs and links may represent mappings between ACs and links. Also, the mapping between the link and the AC may indicate the mapping between the TID and the link.
- a TID may be mapped to each of a plurality of links.
- the mapping may be to designate a link through which traffic corresponding to a specific TID or AC can be exchanged.
- a TID or AC that can be transmitted for each transmission direction in the link may be designated.
- a default setting may exist in the mapping between the TID and the link. Specifically, when there is no additional configuration in the multi-link configuration, the multi-link device may exchange frames corresponding to the TID in each link according to the default configuration. In this case, the basic setting may be that all TIDs are exchanged in any one link. Any TID or AC can always be mapped to at least any one link at any time. Management frames and control frames can be transmitted on all links.
- the ACK may also be transmitted based on the link to which the TID or AC is mapped. For example, a block ACK agreement may be determined based on the mapping between the TID and the link. In another specific embodiment, the mapping between the TID and the link may be determined based on block ACK agreement. Specifically, a block ACK agreement may be established for a TID mapped to a specific link.
- an AC or TID having a higher priority may be mapped to a link in which a relatively small number of stations operate or a link having a good channel state.
- the station can be kept in the power saving state for a longer period of time.
- FIG. 10 shows that transmission of different links is simultaneously performed in a multi-link operation according to an embodiment of the present invention.
- simultaneous operation in the multi-link may not be supported. For example, it may not be supported for a multi-link device to perform transmission simultaneously on a plurality of links, simultaneously perform reception on a plurality of links, or perform transmission on one link and reception on another link at the same time. This is because reception or transmission performed on one link may affect reception or transmission performed on another link. Specifically, transmission in one link may act as interference in another link. Interference acting on another link in one link of one multi-link device may be referred to as internal leakage. The smaller the frequency spacing between the links, the greater the internal leakage may be. If the internal leak is not too large, when transmission is performed on one link, transmission may be performed on the other link.
- simultaneous transmit and receive simultaneous transmission and reception
- STR simultaneous transmission and reception
- a multi-link device that transmits simultaneously on a plurality of links, performs transmission on one link and simultaneously performs reception on another link, or simultaneously performs reception on a plurality of links may be referred to as an STR.
- the multi-link device may support the STR or may only support it limitedly. Specifically, the multi-link device can support STR only under specific conditions. For example, when the multi-link device operates as a single radio, the multi-link device may not perform STR. Also, when the multi-link device operates with a single antenna, the STR of the multi-link device may not be performed. In addition, when an internal leak is detected to be larger than a predetermined size, the multi-link device may not be able to perform STR.
- Stations may exchange information about their STR capabilities with other stations.
- the station may exchange information on whether or not the ability of the station to simultaneously perform transmission on a plurality of links or simultaneously perform reception on a plurality of links is limited with other stations.
- the information on whether the ability to perform transmission or reception in a plurality of links is limited may indicate whether transmission and reception can be performed simultaneously in a plurality of links, simultaneous transmission, or simultaneous transmission.
- the information on whether the ability to perform transmission or reception in a plurality of links is limited may be information indicated for each step.
- the information on whether the ability to perform transmission or reception is limited in a plurality of links may be information indicating a step of indicating the size of internal leakage.
- the information indicating the step of indicating the size of the internal outflow may be information indicating the step of indicating the size of the interference generated due to the internal outflow. In another specific embodiment, it may be information instructing a step of indicating a frequency interval between links that may have an effect on internal leakage. Also, the information indicating the step of indicating the size of the internal outflow may be information indicating the relationship between the frequency interval between links and the size of the internal outflow for each step.
- a first station STA1 and a second station STA2 are affiliated with one non-AP multi-link device.
- the first AP (AP1) and the second AP (AP2) may be associated with one non-AP multi-link device.
- a first link (link 1) is established between the first AP (AP1) and the first station (STA1)
- a second link (link 2) is established between the second AP (AP2) and the second station (STA2) do.
- the non-AP multi-link device may restrictively perform STR.
- the reception of the first station STA1 on the first link Link 1 is performed on the second link Link 2 may be disturbed by For example, in the following case, the reception of the first station STA1 in the first link Link 1 may be interrupted by the transmission performed in the second link Link 2 .
- the second station STA2 transmits the first data Data1
- the first AP AP1 sends an Ack for Data1 response to the first data Data1 to the first station. (STA1).
- the second station STA2 transmits second data Data2.
- the transmission time of the second data Data2 and the transmission time of the response Ack for Data1 to the first data Data1 may overlap.
- interference may occur in the first link Link1 due to transmission from the second link Link2 to the second station STA2 . Accordingly, the first station STA1 may not receive the response Ack for Data1 to the first data Data1.
- a multi-link device may independently perform channel access on a plurality of links.
- the channel access may be a backoff-based channel access.
- the multi-link device may start transmitting simultaneously in the plurality of links.
- the multi-link device has a back-off counter of 0 as well as in the link where the back-off counter reaches 0. Channel access can be performed on other links that are not.
- the multi-link device may perform energy detection in other links whose backoff counters do not reach 0.
- the multi-link device may perform channel access not only in a link in which the backoff counter reaches 0 but also in a link in which energy is sensed. Through this, the multi-link device can start transmitting simultaneously on a plurality of links.
- the threshold value used for energy sensing may be smaller than the threshold value used when determining whether to decrease the backoff counter.
- the multi-link device may detect any type of signal as well as a wireless LAN signal.
- the multi-link device may detect not only a wireless LAN signal but also any type of signal. Internal leakage may not be detected as a wireless LAN signal. In this case, the multi-link device may sense a signal detected due to internal leakage as energy detection. Also, as described above, the threshold value used for energy sensing may be smaller than the threshold value used when determining whether to reduce the backoff counter. Therefore, even while transmission is being performed on one link, the multi-link device can decrease the backoff counter on the other link.
- the multi-link device may determine whether a station operating in each link can operate independently.
- the degree of interference between the links may be the amount of interference detected by another station of the multi-link device when any one station of the multi-link device performs transmission on any one link.
- the operation of the second station may be restricted. Specifically, reception or channel access of the second station may be restricted. This is because, when interference occurs, the second station may fail to decode the signal it receives due to the interference. Also, when interference occurs, when the second station accesses the channel using the backoff, the second station may determine that the channel is in use.
- the first station and the second station can operate independently. Specifically, when transmission in the first link of the first station of the multi-link device causes interference of less than a predetermined amount to the second station of the multi-link device operating in the second link, the first station and the second station Channel access can be performed independently. In addition, when transmission in the first link of the first station of the multi-link device causes interference of less than a predetermined amount to the second station of the multi-link device operating in the second link, the first station and the second station Transmission or reception can be performed independently.
- the second station when interference of less than a predetermined magnitude occurs, the second station can succeed in decoding a received signal even in the presence of interference.
- the second station when interference less than a predetermined size occurs, when the second station accesses the channel using the backoff, the second station may determine that the channel is idle.
- the degree of interference occurring between stations of the multi-link device may vary depending on the hardware characteristics of the multi-link device as well as the interval between frequency bands of links in which the stations operate. For example, internal interference generated in a multi-link device including an expensive radio frequency (RF) device may be smaller than internal interference generated in a multi-link device including a low-cost RF device. Accordingly, the degree of interference occurring between stations of the multi-link device may be determined based on the characteristics of the multi-link device.
- RF radio frequency
- FIG. 10 shows that the magnitude of interference generated varies according to an interval between frequency bands of a link and characteristics of a multi-link device.
- the first multi-link device MLD#1 includes a first station STA1-1 operating in a first link Link1 and a second station STA1- operating in a second link Link2. 2) is included.
- the second multi-link device MLD#2 includes a first station STA2-1 operating on a first link Link1 and a second station STA2-2 operating on a second link Link2.
- the frequency interval between the first link Link1 and the second link Link2 in which the first multi-link device MLD#1 operates and the first link Link1 in which the second multi-link device MLD#2 operates is the same.
- the magnitude of interference generated due to the difference between the characteristics of the first multi-link device MLD#1 and the characteristics of the second multi-link device MLD#2 is different.
- the magnitude of the interference generated in the second multi-link device MLD#2 may be greater than the magnitude of the interference generated in the first multi-link device MLD#1.
- the magnitude of interference may vary depending on the characteristics of the multi-link device, and whether the STR is supported for each multi-link device, information on whether to support the STR needs to be exchanged.
- the multi-link device may signal whether a station included in the multi-link device supports STR.
- the AP multi-link device and the non-AP multi-link device may exchange whether the AP included in the AP multi-link device supports STR and whether the STA includes the non-AP multi-link device supports the STR.
- an element indicating whether STR is supported may be used.
- An element indicating whether STR is supported may be referred to as an STR support element.
- the STR support element may indicate whether the station of the multi-link device that has transmitted the STR support element through 1 bit supports STR.
- the STR support element may indicate whether each of the stations included in the multi-link device transmitting the STR support element supports STR by bit.
- the value of the bit when the station supports the STR, the value of the bit may be 1, and when the station does not support the STR, the value of the bit may be 0.
- the multi-link device that has transmitted the STR support element includes a first station (STA1), a second station (STA2), and a third station (STA3), and the first station (STA1) and the third station (STA3) use the STR If the STR support element is supported and the second station STA2 does not support the STR, the STR support element may include a field with 101 1b . It is assumed that stations operating in different frequency bands support STR, and the STR support element may omit signaling whether STR is supported between stations operating in different frequency bands.
- the first station STA1 operates on the first link of 2.4 GHz
- the second station STA2 and the third station STA3 operate on the second link and the third link of 5 GHz, respectively.
- the STR support element may indicate that STR is supported between the second station STA2 and the third station STA3 using 1 bit.
- the STR support element may include only one bit when there are two stations signaled by the STR support element.
- a relationship between a link located at 2.4 GHz and a link located at 5 GHz or 6 GHz among links of a multi-link device may always be determined as an STR. Accordingly, signaling may be omitted for the STR of the link located at 2.4 GHz and the link located at 5 GHz or 6 GHz.
- the operation of the station of the multi-link device may be substituted with the operation of the multi-link device.
- the operation of the AP may be replaced with the operation of the non-AP station, and the operation of the non-AP station may be replaced with the operation of the AP. Therefore, the operation of the AP of the non-STR multi-link device is replaced with the operation of the non-AP station of the non-STR multi-link device, and the operation of the non-AP station of the STR multi-link device is the operation of the AP of the STR multi-link device. may be substituted.
- the operation of the non-AP station of the non-STR multi-link device is replaced with the operation of the AP of the non-STR multi-link device
- the operation of the AP of the STR multi-link device is the operation of the non-AP station of the STR multi-link device.
- FIG 11 shows an operation of a multi-link device when a link is changed according to an embodiment of the present invention.
- the STR support element may be exchanged. This is because, as described above, whether the station supports the STR may vary depending on the distance between the frequency bands of the link, and when the frequency band of the link is changed, whether the station supports the STR may be changed.
- the frequency band of the link may include at least one of a center frequency change of the link, a bandwidth change of the frequency band, and a 20 MHz main channel.
- the AP and the station may exchange STR support elements through requests and responses.
- the STR support element may be exchanged without a separate request.
- the frequency band of the link is changed, the operating channel of the station is changed.
- the station of the non-AP multi-link device may request the AP to change the link.
- the station of the non-AP multi-link device may request a change of at least one of a center frequency change, a bandwidth change of a frequency band, and a 20 MHz main channel.
- the link change request may be transmitted to the AP through the link requesting the change.
- the link change request may be transmitted to the AP through a link that does not request the change.
- the link change request may include information indicating a link requesting change.
- the information indicating the link may be a number identifying the link.
- the link change may be a change of an operating channel within one frequency band.
- the change of the link may include information on how to change the link.
- the link change request may indicate whether to move the center frequency of the link to a frequency higher than the current center frequency or to move the center frequency of the link to a frequency lower than the current center frequency.
- the link change request may implicitly indicate a change to a frequency band away from an adjacent link.
- the link change request may indicate to reduce the bandwidth of the link.
- the link change request may request a change in the location of the primary channel. Specifically, the link change request may indicate to change the position of the primary channel to a channel of a lower frequency band or a channel of a higher frequency band than the current position of the primary channel.
- the AP receiving the link change request may change the link according to the link change request. Also, in a specific embodiment, the AP receiving the link change request may ignore the link change request.
- the second station STA2 and the third station STA3 of the non-AP multi-link device do not support the STR.
- the non-AP multi-link device requests the AP multi-link device to change the third link Link3.
- the AP multi-link device changes the operation link of the third AP (AP3).
- the third station STA3 operating in the third link link3 to be changed may transmit a change request to the third AP AP3.
- the station not operating in the third link link3 may transmit a change request to the AP not operating in the third link link3.
- the AP may broadcast information about the link change through a beacon frame.
- the information on the link change may include information on the frequency of the link.
- the information about the frequency of the link may include at least one of a change of a center frequency of the link, an operating bandwidth, and a main channel.
- the link change information may include link change time information.
- the link change may be completed at the time of transmitting a beacon including information about the link change.
- the link on which the third station STA3 operates is changed so that the third station STA3 and the second station STA2 may support the STR.
- the non-AP multi-link device may transmit the STR support element to the AP multi-link device to signal whether the changed STR is supported.
- Link change as described above may not be allowed, or STR may not be supported even through link change.
- the AP multi-link device may support the STR, but the non-AP multi-link device may not support the STR.
- a relatively expensive device may be used for the AP multi-link device and a relatively inexpensive device may be used for the non-AP multi-link device. Therefore, when communicating between multi-link devices, there is a need for a method capable of efficiently performing communication even when any one multi-link device does not support STR.
- the STR may indicate that transmission and reception are performed at the same time. This will be described with reference to FIG. 12 .
- reception and transmission of the non-STR multi-link device may fail.
- channel access on the other link of the non-STR multi-link device may be prohibited.
- backoff of channel access in the other link of the non-STR multi-link device may be prohibited.
- channel access prohibition when reception starts in any one link of the non-STR multi-link device, backoff of channel access in another link of the non-STR multi-link device may be prohibited. It can be set through a specific bit of memory, such as a channel access inhibit flag. Whether or not to prohibit channel access can be shared through a memory inside the multi-link device. Through this embodiment, channel access prohibition can be implemented without a separate frame exchange.
- channel access prohibition used in this specification indicates prohibition of channel access or transmission in order to protect transmission or reception of a NON-STR multi-link device unless otherwise specified.
- channel access prohibition on the second link due to reception performed on the first link may be released based on when the reception on the first link is completed. Specifically, the channel access prohibition on the second link due to reception performed on the first link may be released when reception on the first link is completed.
- the channel access prohibition on the second link due to reception performed on the first link may be released based on the time point at which the ACK is transmitted after the reception is completed on the first link. Specifically, the channel access prohibition in the second link due to reception performed in the first link may be released at a time when the ACK is transmitted after the reception in the first link is completed. In another specific embodiment, in a specific embodiment, the channel access prohibition in the second link due to reception performed in the first link may be released when the ACK transmission is completed after the reception in the first link is completed. In addition, immediately after the channel access prohibition is lifted, the station can immediately decrement the backoff counter without additional sensing. In this case, the additional sensing may indicate sensing performed during DCF Interframe Space (DIFS).
- DIFS DCF Interframe Space
- the station when the channel is idle for a predetermined time just before the channel access prohibition is released, the station may immediately decrease the backoff counter without additional sensing.
- the predetermined time may be any one of PCF Interframe Sapce (PIFS), DIFS, Short Interframe Sapce (SIFS), and Arbitration Interframe Space (AIFS).
- the non-STR multi-link device includes a first station STA1 operating in a first link Link1 and a second station STA2 operating in a second link Link2.
- the second station STA2 performs transmission on the second link Link2 while the first station STA1 performs reception, intra-device interference occurs.
- the channel access of the second station STA2 performed in the second link Link2 is prohibited.
- the channel access prohibition is released.
- the second station STA2 may decrease the previous backoff counter value from 3 to 2 by 1 without additional sensing.
- a single block (Tx solid line, Rx dotted line) is used in the drawing used in FIG. 12 to express Rx and Tx, and even though the single block does not show a separate Ack Block, Tx / Ack reception, It can be understood as expressing an operation including Rx / Ack transmission. This can be equally applied to drawings to be described later.
- the station may stop receiving the PPDU. In this case, the operation of releasing the channel access prohibition of the multi-link device becomes a problem.
- the intended recipient is used synonymously with the destination station.
- FIG 13 shows an operation of releasing the channel access prohibition when it is confirmed that the intended recipient of the PPDU received by the station of the non-STR multi-link device is not the station according to an embodiment of the present invention.
- the station may release the channel access prohibition.
- the station may determine whether the station is an intended recipient of the PPDU based on information indicating the recipient address of the signaling field of the PPDU.
- the information indicating the receiver address of the signaling field of the PPDU may be the value of the STA-ID field of the EHT-SIG field described above.
- the station may determine whether the STA-ID field of the EHT-SIG field indicates the station.
- the station may determine whether the station is an intended recipient of the PPDU based on the value of the RA field of the MAC frame included in the PPDU.
- the station may determine whether the RA field of the MAC frame included in the PPDU indicates the station.
- the non-STR multi-link device includes a first station STA1 operating in a first link Link 1 and a second station STA2 operating in a second link Link 2 .
- the first station STA1 receives the PPDU.
- the first station STA1 determines that the intended recipient of the received PPDU is not the first station STA1, and stops receiving the PPDU.
- the first station STA1 may release the channel access prohibition of the second station STA2 . Even if the channel access prohibition of the second station STA2 is released, the channel access of the second station STA2 may be delayed according to the NAV set to the second station STA2 .
- a station from which the channel access prohibition is released may decrease the backoff counter by 2 or more immediately after the channel access prohibition is released. Since the other station performed the backoff procedure while the station's channel access is prohibited, it is to balance the channel access opportunity with other stations.
- the station where channel access is prohibited may perform a channel access procedure that reduces CCA (CSMA) and a backoff counter while channel access is prohibited.
- the non-STR multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- channel access of the second station STA2 is prohibited while the first station STA1 performs reception.
- the second station STA2 may perform a channel access procedure to reduce the CCA (CSMA) and the backoff counter.
- CSMA CCA
- the second station STA2 decreases the backoff counter.
- a station where channel access is prohibited may delay transmission without starting transmission even if the backoff counter reaches zero while channel access is prohibited. In this case, the station may maintain the value of the backoff counter as 0. Also, even if the station delays transmission, the station can maintain the value of the CW as it is. Therefore, since the channel accessed by the station is busy, it is differentiated from doubling the value of the CW by the station. This is because the reason for the delay in transmission is not when it is determined that the channel is in use. While the channel access of the second station STA2 is prohibited in FIG. 14B , the second station STA2 may perform a channel access procedure to reduce the CCA (CSMA) and the backoff counter.
- CSMA CCA
- the second station STA2 decreases the backoff counter. While the channel access of the second station STA2 is prohibited, the backoff counter of the second station STA2 reaches zero. The second station STA2 delays the transmission and starts the transmission after the channel access prohibition is released.
- the channel access prohibition may include prohibiting transmission to the second station when the first station of the non-STR multi-link device performs transmission. Also, the channel access prohibition may include prohibiting transmission of the second station when the first station of the non-STR multi-link device performs reception.
- FIG. 15 shows an operation in which a station performs transmission after releasing a channel access prohibition according to an embodiment of the present invention.
- transmission may be performed on a first link among a plurality of links on which a non-STR multi-link device operates, so that transmission may be prohibited on a second link.
- the transmission in the second link may start with an RTS/CTS frame exchange.
- the non-STR multi-link device may start exchanging RTS/CTS frames on the second link.
- the station may start exchanging request to send/clear to send (RTS/CTS) frames before starting delayed transmission.
- a station whose transmission is delayed due to channel access prohibition transmits an RTS frame before starting the delayed transmission.
- the station starts delayed transmission after receiving the CTS frame in response to the RTS frame.
- the station may transmit a frame including only a part of the delayed transmission.
- the station may transmit the non-transmitted part of the delayed transmission.
- the station may not perform the transmission of the untransmitted part of the delayed transmission.
- the above-described embodiments may be compulsorily applied to transmission performed after the channel access prohibition is released.
- the RTS/CTS frame was used to solve the hidden node problem, and could be used based on the size of transmission data.
- the RTS/CTS frame is to prevent transmission collision with a station that intends to perform delayed transmission in order to protect transmission or reception of the NON-STR multi-link device.
- the second station of the non-STR multi-link device can always determine that the channel state of the link in which the second station operates is busy. have. Accordingly, the second station may determine that the channel is in use due to interference within the device even when the channel of the link in which the second station operates is idle.
- the other station of the non-STR multi-link device is referred to as a blind state. do. Due to the circumstances described above, it may be difficult for a station in a blind state to attempt transmission by performing a backoff procedure. In addition, it may be difficult for a station in a blind state to start receiving or successfully decode a PPDU due to the aforementioned circumstances. Therefore, a transmission method in consideration of the station in the blind state is required. This will be described with reference to FIG. 16 .
- 16 shows transmission performed based on the state of a station in a non-STR multi-link device according to an embodiment of the present invention.
- a station that intends to perform transmission to a station of a non-STR multi-link device may determine whether to perform transmission according to whether a station of a non-STR multi-link device is in a blind state.
- the station to perform transmission to the station of the non-STR multi-link device may be a station included in the STR multi-link device.
- a station to perform transmission to a station of a non-STR multi-link device may be an AP included in the AP multi-link device, and the non-STR multi-link device may be a non-AP multi-link device.
- a station that intends to perform transmission to a station of a non-STR multi-link device may determine whether a station of a non-STR multi-link device is in a blind state as follows.
- a station that wants to perform transmission may determine whether another station of the multi-link device including the station is performing transmission to the corresponding non-STR multi-link device. If another station of the multi-link device including the station is performing reception from the non-STR multi-link device, the station may determine that the station of the non-STR multi-link device that is to receive the station transmission is in the blind state. .
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second station STA2 is transmitting to the second AP AP2.
- the second AP AP2 may inform the first AP AP1 that reception is being performed from the second station STA2 .
- the second AP AP2 may inform the first AP AP1 that the subject of transmission to the second AP AP2 is the second station STA2 .
- the second AP AP2 may notify the first AP AP1 that the second station STA2 is currently transmitting.
- the first AP AP1 may determine that the first station STA1 is in the blind state based on the notification.
- Stations in a multi-link device may operate through a common MAC. Therefore, information exchange between the first AP (AP1) and the second AP (AP2) described above may not be explicitly performed.
- the station may not perform transmission to the station in the blind state. This is because, even if transmission is performed to the station in the blind state, there is a high possibility that the station in the blind state cannot start reception or the station in the blind state cannot decode the PPDU. In this case, the station may cancel transmission to the station in the blind state and perform transmission to another station.
- the STR multi-link device may perform transmission to the non-STR multi-link device in a plurality of links. Specifically, when the STR multi-link device transmits to the non-STR multi-link device in the first link, the STR multi-link device may start transmitting to the non-STR multi-link device in the second link. In this case, the STR multi-link device may determine the length of transmission performed in the second link based on the transmission for the non-STR multi-link device. Specifically, the STR multi-link device may determine the length of transmission for the non-STR multi-link device on the second link based on the length of the transmission for the non-STR multi-link device on the first link.
- the STR multi-link device may terminate transmission in the first link and transmission in the second link at the same time. This is because transmission to any one of the stations of the non-STR multi-link device ends first, so that while any one of the stations of the non-STR multi-link device transmits a response to the transmission, for example, an ACK, the other of the non-STR multi-link device This is to prevent transmission to the station from being performed.
- a plurality of stations of a non-STR multi-link device may simultaneously transmit responses to transmissions for the plurality of stations.
- the STR multi-link device cannot determine the status of a station included in the non-STR multi-link device in real time. Therefore, even if the STR multi-link device operates according to the embodiments described with reference to FIG. 16, interference or transmission collision may occur between links in which the non-STR multi-link device operates. For example, in the embodiment of FIG. 16 , before recognizing that the second station STA2 is performing transmission to the second AP AP2 , the first AP AP1 starts transmission to the first station STA1 . can As described above, the probability of occurrence of interference or collision between links may be greater than the probability of occurrence of inter-link interference or transmission collision. This will be described in more detail with reference to FIG. 17 .
- Transmission of the second station of the non-STR station multi-link device to the second AP of the STR AP multi-link device is the same as the transmission of the first AP of the STR AP multi-link device to the first station of the non-STR station multi-link device If they start at the same time, transmission conflicts may occur between links.
- Figure 17(a) shows this. This may occur because, as described above, the STR multi-link device cannot determine the status of a station included in the non-STR multi-link device in real time.
- the transmission of the second station of the non-STR station multi-link device to the second AP of the STR AP multi-link device is transmitted to the first station of the non-STR station multi-link device of the first AP of the STR AP multi-link device.
- Transmission conflicts may occur between links, even if they started earlier than transmission.
- Figure 17(b) shows this. This is because it may take time for the second AP (AP2) to notify the first AP (AP1) that the second station STA2 is performing transmission. As such, transmission collision occurs between stations that start transmission at different time points, so the probability of occurrence of interference or collision between the stations may be greater than the probability of occurrence of interference or collision within the link.
- the time for identifying the sender of the PPDU received by the AP of the STR multi-link device is delayed, the probability of occurrence of interference or transmission collision between links may increase. Therefore, a method is needed to solve this.
- the channel access of the other station of the STR multi-link device may not be performed. However, when channel access is prohibited in this way, the meaning of implementing the STR function may disappear. Therefore, an operation method other than channel access prohibition of the STR multi-link device may be required. This will be described with reference to FIG. 18 .
- the User field of the EHT-SIG of the EHT UL PPDU may indicate an identifier (STA-ID) of a station transmitting the EHT UL PPDU.
- STA-ID identifier
- the User field of the EHT-SIG of the EHT PPDU may indicate an identifier of a station transmitting the EHT UL PPDU.
- the multi-link device receiving the EHT PPDU may identify a station transmitting the EHT PPDU based on the User field of the EHT-SIG of the EHT UL PPDU. Through this, the AP multi-link device may determine a station transmitting the EHT UL PPDU, and the AP multi-link device may determine a transmission target device. Specifically, the AP multi-link device may determine whether there is a high probability that the transmission to be performed will fail due to inter-link collision. In addition, when there is a high probability that the transmission that the AP multi-link device is trying to perform fails, the AP multi-link device may delay the transmission to be performed and perform another transmission.
- FIG. 18 shows an operation in which an STR multi-link device stops transmission to a non-STR multi-link device according to an embodiment of the present invention.
- the STR multi-link device determines that the station of the non-STR multi-link device is in the blind state during transmission to the station of the non-STR multi-link device, the STR multi-link device is the station of the non-STR multi-link device that is in the blind state You can stop sending to .
- the STR multi-link device is a non-STR multi-link device based on a value indicated by the STA (AID)-ID in the signaling field of the received PPDU or the TA (transmitting address) field of the MAC frame included in the received PPDU. It can be determined whether the station is in a blind state.
- the STA-ID may be a value indicating a station transmitting the UL PPDU in the UL PPDU.
- the STR multi-link device is included in the non-STR multi-link device when the value indicated by the STA (AID)-ID in the signaling field of the received PPDU indicates the first station included in the non-STR multi-link device It may be determined that the second station is in a blind state.
- the second station included in the non-STR multi-link device when the TA field of the MAC frame included in the received PPDU indicates the first station included in the non-STR multi-link device, the second station included in the non-STR multi-link device is in a blind state can be judged that Specifically, when the station transmitting the PPDU indicated by the signaling field of the PPDU is the first station or the TA field of the MAC frame included in the PPDU is the first station, the STR multi-link device is the second station included in the non-STR multi-link device. It may be determined that the station is in a blind state.
- the STR multi-link device may determine that the other station of the non-STR multi-link device is in a blind state by confirming that any one station of the non-STR multi-link device performs transmission. The operation of the station after transmission cancellation will be described first.
- the station that canceled transmission to the station of the non-STR multi-link device may try to transmit to a station different from the station of the non-STR multi-link device.
- the station that has canceled transmission to the station of the non-STR multi-link device may perform transmission to a station different from the station of the non-STR multi-link device without a separate backoff procedure.
- transmission to the station of the non-STR multi-link device is stopped.
- the canceled station may perform transmission to a station different from that of the non-STR multi-link device.
- the predetermined time interval may be any one of SIFS, PDIF, and DIFS.
- a station that cancels transmission to a station of a non-STR multi-link device may transmit traffic having the same priority as the traffic of the canceled transmission or traffic having a higher priority. This is because, in the case of transmitting traffic corresponding to a lower priority than the priority of the traffic used when accessing the channel for the canceled transmission, it may not be fair.
- the station of the STR multi-link device may be an AP.
- a station that has canceled transmission of a non-STR multi-link device to a station may initialize the configured TXOP. Specifically, a station that has canceled transmission to a station of a non-STR multi-link device may transmit a CF-End frame after canceling transmission. This enables other stations operating in a link for which transmission is scheduled to use the link.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second station STA2 is transmitting to the second AP AP2.
- the first AP AP1 determines that the first station STA1 is in a blind state while performing transmission to the first station STA1 . Accordingly, the first AP (AP1) stops transmission to the first station (STA1). After stopping transmission to the first station STA1 in FIG.
- the first AP AP1 performs transmission to a station different from the first station STA1 as in the previously described embodiment. After stopping transmission to the first station STA1 in FIG. 18B , the first AP AP1 transmits a CF-END frame as in the embodiment described later.
- the station When the station stops transmitting, it may not transmit the next fragment after transmitting the fragment being transmitted. In another specific embodiment, the station may immediately stop transmission of a packet that was being transmitted.
- the STR multi-link device stops transmission to the station of the non-STR multi-link device in the blind state and performs transmission to a station different from the station of the non-STR multi-link device in the blind state, stable For reception, it is necessary to inform the other station that a transmission to another station may be performed. A method for this will be described.
- a station different from a station of a non-STR multi-link device in a blind state is referred to as another station.
- the station of the STR multi-link device may insert the address of another station into the MAC frame. Specifically, the station of the STR multi-link device may insert the address of the intended recipient of the MAC frame into the receiving address (RA) of the MAC frame, and insert the address of another station into a separate field. In another specific embodiment, the station of the device may insert the address of another station into the EHT-SIG. Specifically, the station of the STR multi-link device may insert the address of a station different from the address of the intended recipient of the PPDU in the User field of the signaling field of the PPDU. In this case, the address of another station may be inserted after the address of the intended recipient of the PPDU in the User field of the signaling field of the PPDU.
- the station may monitor the reception of the PPDU for a predetermined time even after recognizing that the intended recipient of the received PPDU is not the station. Specifically, the station may monitor whether reception of the PPDU continues for a predetermined time even after recognizing that the intended recipient of the received PPDU is not the station. Through this, the station can determine whether transmission of the PPDU is stopped and transmission to the station starts. In these embodiments, when it is determined that PPDU transmission continues for a predetermined time, the station may enter a doze state. When it is determined that transmission of the PPDU is not continued for a predetermined time, the station may maintain a wake-up state. In this case, when a new PPDU is received by the station, the station may decode the PPDU.
- the station transmitting the PPDU may insert information signaling that the transmission of the PPDU may be stopped into the PPDU.
- Information signaling that PPDU transmission may be stopped may be a 1-bit subfield. For example, when the value of the subfield signaling that PPDU transmission can be stopped is 1, the station receiving the PPDU transmits the PPDU from the time indicated by the Length field of the PPDU signaling field and the Duration field of the MAC frame. It may be determined that transmission of the PPDU may be previously stopped. When the station determines that PPDU transmission can be stopped before the time point indicated by the Length field of the PPDU signaling field and the Duration field of the MAC frame, the station may defer entering the power saving state. Also, the station transmitting the PPDU may insert information signaling that transmission may be stopped in the reserved field of the PPDU into the PPDU.
- the value of CW used for channel access may be doubled as in a general transmission failure.
- the CW value used for channel access may not be doubled, unlike general channel access failure or transmission failure. That is, the station may maintain the CW value used for channel access as it is.
- the doubling of the value of CW is to increase the range of the number that can be the value of the backoff counter to reduce the probability of transmission collision. This need may be less if the station can clearly recognize that there is a transmission collision between links.
- the station doubling the value of CW may delay transmission.
- the station needs to double the CW value. This will be described with reference to FIG. 19 .
- FIG. 19 shows that the STR multi-link device processes a CW value when recognizing a transmission collision between links according to an embodiment of the present invention.
- the station may sense the channel state after canceling the transmission. If it is sensed that the channel is not idle, the station may double the value of CW. In this case, the doubling may follow the embodiment described with reference to FIG. 6 . Also, when it is sensed that the channel is idle, the station may maintain the value of CW. In this embodiment, even if the channel is sensed as being idle, the possibility of transmission collision in the link is low, and thus, it is treated differently from the case of successful transmission.
- the AP of the AP multi-link device may acquire a backoff counter in the CW without increasing the CW.
- the AP of the AP multi-link device does not increase the CW.
- the second station of the non-STR multi-link device performs transmission based on the transmission station of the PPDU indicated by the signaling field of the PPDU or the station indicated by the TA field of the MAC frame included in the PPDU. can determine whether When EDCA is applied in the above-described embodiments, the procedures for CW adjustment and backoff counter generation may be performed for each AC.
- the STR multi-link device may determine whether transmission of the PPDU has failed based on whether a response to the PPDU has been received. In this case, the STR multi-link device may not consider whether the station receiving the PPDU is included in the non-STR multi-link device. For example, even if the first station receiving the PPDU is included in the non-STR multi-link device and the second station of the non-STR multi-link device performs transmission, the first station fails to transmit a response to the PPDU, The STR multi-link device may determine that transmission of the PPDU has failed.
- the STR multi-link device may increase the CW value to the next larger value among possible values of the CW value. In this case, when the value of CW is the maximum value, the STR multi-link device may maintain the value of CW as the same value.
- the station when it is sensed that the channel is idle, the station may set the value of CW as the minimum value of CW of traffic (CW_min). In this embodiment, when it is sensed that the channel is idle, since the possibility of transmission collision in the link is low, it is treated in the same way as when transmission is successful. The station may apply the above-described embodiments to the CW of AC of traffic included in the canceled transmission.
- the station may not increase the Retry Counter.
- the Retry Counter may include at least one of a long retry counter and a short try counter.
- canceling transmission may include at least one of stopping transmission or delaying transmission before starting transmission.
- the station may not start exchanging RTS/CTS frames before attempting transmission after canceling transmission. This is because the NAV has already been set through the CTS-to-Self frame.
- the station may attempt the transmission without a backoff procedure.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second station STA2 is transmitting to the second AP AP2.
- the first AP AP1 determines that the first station STA1 is in a blind state while performing transmission to the first station STA1 . Accordingly, the first AP (AP1) stops transmission to the first station (STA1).
- AP1 operating in a first link
- AP2 operating in a second link
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second station STA2 is transmitting to the second AP
- the first AP AP1 determines that the channel of the first link Link 1 is idle. At this time, since there is no TXOP remaining, the first AP (AP1) accesses the channel through the backoff procedure. In FIG. 19B , the first AP AP1 determines that the channel of the first link Link 1 is not idle. At this time, since the TXOP remains, the first AP (AP1) attempts transmission without a backoff procedure.
- the station canceling the STR may perform transmission to a station different from that of the non-STR multi-link device.
- the duration of the predetermined time period may be a problem.
- the station receiving the PPDU of the canceled transmission may fail to decode the PPDU.
- the station that fails to decode the PPDU may start a backoff procedure. Therefore, there is a problem whether the predetermined time interval is set to be longer than the EIFS or to be set equal to or equal to the EIFS. This will be described with reference to FIG. 20 .
- FIG. 20 shows an operation in which an STR multi-link device performs channel access again after stopping transmission to a non-STR multi-link device according to an embodiment of the present invention.
- the predetermined time period may be DIFS. This is considering that the station of the STR multi-link device obtained a channel access opportunity through a contention procedure, and lost the acquired channel access opportunity due to transmission collision between links. That is, since the channel access opportunity is obtained through the station contention procedure of the STR multi-link device, priority is given to other stations performing channel access.
- DIFS may be replaced with AIFS[AC].
- the predetermined time interval as shown in FIG. 20(b) may be an EIFS. This is because the STR multi-link device may be considered to have already exhausted the transmission opportunity, and fairness with other stations is considered.
- the predetermined time period may be DIFS.
- the station receiving the PPDU detects that transmission of the PPDU is stopped, the station may sense whether the channel is idle during DIFS instead of EIFS. In this case, if it is sensed that the channel is idle during DIFS, the corresponding station may start a backoff procedure.
- DIFS may be replaced with AIFS[AC].
- the STR multi-link device may recognize that transmission collision between links may occur. Specifically, when the first station of the STR multi-link device completes the backoff procedure, the second station of the STR multi-link device may be receiving the PPDU. In this case, if the second station does not complete decoding the signaling field of the PPDU, the first station cannot recognize that a transmission collision between links has occurred, but may determine that there is a possibility. In this case, the first station may insert information indicating that transmission may be stopped in the transmitted PPDU as described above. In addition, the NSTR multi-link device may transmit a CTS-to-Self frame before transmission to the non-STR multi-link device for stable and efficient transmission. This will be described with reference to FIG. 21 .
- 21 shows an operation in which the STR multi-link device transmits a CTS-to-Self frame before transmission to the non-STR multi-link device according to an embodiment of the present invention.
- the station of the STR multi-link device may transmit a CTS-to-Self frame before transmission to the non-STR multi-link device.
- the second station of the STR multi-link device attempts to transmit to the non-STR multi-link device while the first station of the STR multi-link device performs reception
- the second station of the STR multi-link device A CTS-to-Self frame may be transmitted before transmission to the STR multi-link device.
- the second station can secure the TXOP for transmission to the non-STR multi-link device.
- the second station may determine whether transmission to the first station is transmitted from the non-STR multi-link device before performing transmission to the non-STR multi-link device.
- the second station may determine the destination station of the transmission according to whether the transmission for the first station is transmitted from the corresponding non-STR multi-link device. Specifically, when the transmission for the first station is not transmitted from the non-STR multi-link device, the second station may perform the transmission for the non-STR multi-link device. When the transmission for the first station is transmitted from the corresponding non-STR multi-link device, the second station may perform transmission for a station not included in the corresponding non-STR multi-link device.
- the first station triggers transmission of a SU-PPDU for a station of a non-STR multi-link device, an MU-PPDU including data about a station of a non-STR multi-link device, and a station of a non-STR multi-link device
- the first station may cancel the planned transmission.
- the first station is a SU-PPDU for a station that is not a station of a non-STR multi-link device, an MU-PPDU that does not include data for a station of a non-STR multi-link device, and a station of a non-STR multi-link device. Transmission of a PPDU including a trigger frame that does not trigger transmission of may be attempted.
- the first station may start transmission after a time greater than the SIFS from when the CTS-to-Self frame is transmitted. Specifically, the first station may start transmission after PIFS from when the CTS-to-Self frame is transmitted. The station that has transmitted the CTS-to-Self frame should start transmission after SIFS from the time of transmitting the CTS-to-Self frame.
- processing time of the STR multi-link device is required, such as generating an MPDU to be newly transmitted. Therefore, an exception to the regulation on the time interval between the CTS-to-Self frame and transmission may be applied.
- the second station cannot perform transmission in excess of the TXOP obtained by CTS-to-Self.
- the STR multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2). Since the second AP (AP2) performs reception and the first AP (AP1) plans transmission to the station of the non-STR multi-link device, the first AP (AP1) transmits the CTS-to-Self frame before the planned transmission. do. As described above, the first AP (AP1) determines the destination station for transmission based on the determination of the station that has transmitted the PPDU received by the second AP (AP2). In addition, the first AP (AP1) performs transmission after SIFS or PIFS from when the CTS-to-Self frame is transmitted.
- the second station may start the RTS/CTS frame exchange procedure by transmitting an RTS frame instead of transmitting the CTS-to-Self frame. Through this, the second station can obtain an effect similar to that of transmitting the CTS-to-Self frame.
- the second station may acquire the TXOP only when the destination station of transmission is not in a blind state.
- FIG. 22 shows that a plurality of APs included in an STR multi-link device perform transmission to a plurality of stations included in one non-STR multi-link device according to an embodiment of the present invention.
- a plurality of stations included in one non-STR multi-link device may simultaneously perform reception. This is because simultaneous reception by a plurality of stations may cause only relatively small interference.
- 22 shows that a plurality of stations included in one non-STR multi-link device simultaneously perform reception.
- a plurality of APs included in the STR multi-link device are synchronized with the termination of transmission to a plurality of stations included in one non-STR multi-link device. Multiple transmissions may be performed. This will be described with reference to FIG. 23 .
- FIG. 23 shows that a plurality of APs included in an STR multi-link device perform a plurality of transmissions in which the termination of transmission is synchronized to a plurality of stations included in one non-STR multi-link device according to an embodiment of the present invention.
- the multi-link device when a link device far from one link performs transmission, the multi-link device can simplify a channel access procedure for transmission performed on another link. Specifically, when the first station of the multi-link device completes the backoff channel access procedure in the first link, when the channel is idle for a predetermined time period in the link of the second station of the STR multi-link device, the STR multi-link The second station of the device may start transmitting on the second link.
- the channel access procedure of another station of the STR multi-link device may be simplified. Specifically, when the first station of the STR multi-link device completes the backoff channel access procedure of transmission to the first station of the non-STR multi-link device, a predetermined time within the link of the second station of the STR multi-link device If the channel is idle during the period, the second station of the STR multi-link device may start transmission to the second station of the non-STR multi-link device. In this case, it may be PIFS during a predetermined time period.
- This operation may be applied when the first station and the second station of the STR multi-link device perform transmission to stations included in one non-STR multi-link device.
- the first station and the second station may start transmission with a difference within a predetermined time interval.
- the predetermined time period may be a slot time.
- the transmission termination of the first station and the second station may be synchronized.
- the synchronization of the transmission termination of the first station and the second station may indicate that the transmission of the first station and the transmission of the second station are terminated due to a difference within the first predetermined time interval.
- the first preset time interval may indicate within a slot boundary or within a symbol boundary.
- a plurality of stations of the non-STR multi-link device that have received the synchronized transmission end may transmit a subsequent transmission, eg, a response, at the same time.
- the response may include an ACK.
- a transmission following reception is transmitted after SIFS from reception.
- transmitting the following transmission with a slight time difference may make implementation more complicated than transmitting the following transmission at the same time. Accordingly, as described above, the plurality of stations of the non-STR multi-link device that have received the synchronized transmission termination may simultaneously transmit subsequent transmissions.
- an interval between transmission and transmission following at least one of a plurality of synchronized transmissions may be the sum of SIFS and a time within a predetermined time interval.
- a transmission following the first terminated transmission may be transmitted at an interval added by the SIFS from transmission and a time within a predetermined time interval.
- the predetermined time interval may be either a slot time or a symbol length.
- the difference within the predetermined time interval may be a difference between the end of the last transmission among a plurality of transmissions for which the termination of transmission is synchronized, and a transmission that ends earlier among the plurality of transmissions with the synchronization of transmission termination.
- the plurality of stations receiving the transmission may transmit the transmission following synchronization.
- a plurality of subsequent transmissions with synchronized termination of transmission may indicate a plurality of subsequent transmissions transmitted with a time difference within a second predetermined time interval.
- the difference within the second preset time interval may be a difference between the end of the last completed transmission among the plurality of synchronized transmissions and the first completed transmission among the plurality of synchronized transmissions.
- the second preset time period may be smaller than the first preset time period.
- a PPDU whose transmission termination is synchronized in this way may be referred to as a sync PPDU.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the first AP (AP1) and the second AP (AP2) synchronize termination of transmission to the first station STA1 and the second station STA2, respectively. That is, after the first station STA1 ends the transmission, the second station STA2 ends the transmission from the first station STA1 within a predetermined time interval.
- the first station STA1 and the second station STA2 simultaneously transmit ACKs. In this case, the first station STA1 transmits the ACK after the SIFS from the end of the transmission to the first station STA1 and the difference between the end of the transmission to the first station and the end of the transmission to the second station STA2 .
- These embodiments may be applied to transmission in which the ACK policy is not set to No ACK. Specifically, it can be applied even when the ACK policy is not an immediate response.
- the plurality of stations of the multi-link device may simultaneously receive an ACK request and transmit an ACK according to the ACK request. have.
- a plurality of stations of the multi-link device that have received the transmission in which the ACK policy is set to a value other than No ACK within a predetermined time may start ACKing at the same time.
- the non-STR multi-link device When a non-STR multi-link device exists, the non-STR multi-link device must be considered in the operation of setting the TXOP by transmitting the RTS/CTS frame and the CTS-to-Self frame. This will be described with reference to FIGS. 24 to 29 .
- FIG. 24 shows that a multi-link device exchanges RTS/CTS frames according to an embodiment of the present invention.
- the RTS/CTS frame exchange procedure may follow the procedure defined in the existing WLAN.
- the RTS/CTS frame may be used to set the NAV of a station operating on a different link.
- the station receiving the RTS/CTS frame may operate on a link different from the link on which the corresponding station operates, and may transmit the RTS/CTS frame to another station included in the multi-link device including the corresponding station.
- RTS/CTS may not be transmitted as shown in FIG. 24 . That is, a station planning transmission to the first station of the non-STR multi-link device may not attempt to exchange RTS/CTS frames when the second station of the non-STR multi-link device is performing reception.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the first AP (AP1) transmits the RTS frame to the first station (STA1)
- channel access of the second station (STA2) is prohibited.
- the second AP AP2 may determine that the channel access of the second station STA2 is prohibited. Accordingly, the second AP (AP2) does not attempt to exchange RTS/CTS frames with the second station (STA2).
- a hidden node problem may occur. This will be described with reference to FIG. 25 .
- FIG. 25 shows a hidden node problem occurring in the RTS/CTS frame exchange procedure according to the embodiment described with reference to FIG. 24 .
- a station transmitting to a station of a non-STR multi-link device may perform transmission without performing CTS/RTS exchange as described above. At this time, since the TXOP is not set to the other station, the station of the non-STR multi-link device may fail to receive the transmission because the other station tries to transmit.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second AP (AP2) could not transmit the RTS frame before transmission. Therefore, the TXOP for transmission of the second AP (AP2) is not set to the station operating in the second link (Link 2). Accordingly, when the second AP (AP2) transmits to the second station (STA2), the station (OBSS STA) of the other BSS performs transmission in the second link (Link2). Due to this, the second station STA2 fails to receive the transmission from the second AP AP2.
- the following embodiments may be applied.
- the station when any one station of the non-STR multi-link device is performing reception, the station may not be allowed to perform transmission to any station of the non-STR multi-link device. In another specific embodiment, when the station transmits to the first station of the non-STR multi-link device and the second station of the non-STR multi-link device is performing reception, the station performs the transmission simultaneously with the transmission to the second station can do. When the station transmits to the first station of the non-STR multi-link device and the second station of the non-STR multi-link device is performing reception, the station determines the end of the transmission for the first station and the end of the transmission for the second station. can be synchronized.
- the station transmits the transmission to the first station simultaneously with the transmission to the second station.
- the transmission to the second station may be performed by another station of the multi-link device including the station.
- 26 shows that a multi-link device exchanges RTS/CTS frames according to an embodiment of the present invention.
- the second station of the multi-link device while the first station of the multi-link device continues to transmit to the third station of the non-STR multi-link device, the second station of the multi-link device sends the second station of the non-STR multi-link device to the fourth station of the non-STR multi-link device.
- the first station may end transmission to the third station before the time when the fourth station intends to transmit the RTS frame.
- the fourth station can transmit the CTS frame to the second station.
- a TXOP for frame exchange between the second station and the fourth station may be configured.
- the second station of the multi-link device sends the second station of the non-STR multi-link device to the fourth station of the non-STR multi-link device.
- the second station may transmit the RTS frame to the fourth station according to the transmission end time of the first station to the third station.
- the second station may insert padding into the RTS frame.
- the RTS frame may be an RTS frame format in which a transmission length can be flexibly adjusted.
- this RTS frame format is referred to as a multilink (ML)-RTS frame.
- the ML-RTS frame may include a pad field for padding.
- the format of the ML-RTS frame may be the same as the RTS frame format described in FIG. 26 .
- the first station may insert padding into the transmission to the third station in order to match the RTS frame and the transmission end time.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the second AP (AP2) transmits the ML-RTS frame to the second STA (STA2) according to the transmission end time of the first AP (AP1) to the first station (STA1).
- the second station STA2 transmits the ACK to the second AP AP2 .
- a TXOP for frame exchange between the second AP (AP2) and the second station (STA2) is set to stations operating in the channel of the second link.
- the ACK request frame may be transmitted instead of the RTS frame.
- the ACK request frame may include duration information related to the transmission end time.
- a frame including an ACK transmitted in response to the ACK request may also include duration information.
- the duration information of the frame including the ACK may be set according to the duration information of the ACK request frame.
- control frame exchange may include an exchange of a PS-Poll frame and a response frame for PS-Poll.
- channel access of some stations may be prohibited. Even if the station's channel access is prohibited, the station may transmit a response to the control frame. Specifically, even if the station's channel access is prohibited, the station may transmit the CTS frame in response to the RTS frame.
- the first station transmits a response to the control frame with the exception of channel access prohibition.
- the third station transmits the response to the second station included in the multi-link device including the first station. In this case, the third station may perform retransmission for the first station. This is because the third station may expect the transmission to the second station to fail.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link 1) and a second AP (AP2) operating in a second link (Link 2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link 1 and a second station STA2 operating on a second link Link 2 .
- the first AP (AP) performs transmission to the first station (STA1).
- the second AP (AP2) transmits an RTS frame to the second station (STA2). Since the first station STA1 performs reception, channel access of the second station STA2 is prohibited. However, the second station (STA2) transmits the CTS frame to the second AP (AP2) except for channel access prohibition.
- the first AP AP1 may determine that transmission of the first AP AP1 is highly likely to fail due to the CTS frame transmission of the second station STA2 . Accordingly, the first AP (AP1) performs retransmission to the first station (STA1). The retransmission method will be described in more detail with reference to FIG. 28 .
- only some of the packets included in the initial transmission may be retransmitted.
- the station performing the retransmission may retransmit only some of the packets included in the initial transmission.
- the station performing the retransmission may determine some of the packets included in the initial transmission as a packet to be retransmitted based on a time interval in which the station performing the retransmission receives the CTS frame.
- the station performing retransmission may determine a packet transmitted in a time interval including a time interval in which the station performing retransmission among the packets included in the initial transmission received the CTS frame as a packet to be retransmitted.
- the station performing retransmission may retransmit the transmitted packet in a time interval including a time interval in which the station CTS frame performing retransmission is received based on a propagation delay.
- the station performing retransmission may retransmit all packets included in the initial transmission.
- the station performing retransmission may perform retransmission before receiving an ACK for transmission.
- the station performing the retransmission may receive a block ACK indicating whether to receive the initial transmission and the retransmission after performing the retransmission.
- the station performing retransmission may perform retransmission before SIFS after initial transmission.
- a station that has failed to receive due to a control frame transmitted as an exception of channel access prohibition may wait for reception of retransmission without transmitting an ACK.
- the first AP (AP1) retransmits the fourth packet and the fifth packet in consideration of the period in which the second AP (AP2) receives the CTS frame and the transmission delay. After the retransmission, the first AP (AP1) receives an ACK including whether or not the retransmission is received.
- 29 shows that a control frame is transmitted through a link in which a station in which channel access is not prohibited operates, rather than a link in which a station in which channel access is prohibited, operates according to an embodiment of the present invention.
- the multi-link device may transmit the control frame through a link in which a station in which channel access is not prohibited operates, rather than a link in which a station in which channel access is prohibited operates.
- the multi-link device may transmit a control frame through a link currently being received from the multi-link device among stations of the non-STR multi-link device.
- the control frame may be an RTS frame.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link1) and a second AP (AP2) operating in a second link (Link2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link1 and a second station STA2 operating on a second link Link2.
- the first AP (AP1) performs transmission to the first station (STA1). Even if the second AP (AP2) succeeds in the backoff procedure, since the first station (STA1) is receiving the transmission transmitted from the first AP (AP1), the second AP (AP2) transmits the transmission to the second station (STA2).
- the second AP requests the first AP (AP1) to transmit the RTS frame to which the second station STA2 is a receiver.
- the first AP (AP1) may include the RTS frame of which the second station (STA2) is the receiver in the transmission being performed by the first AP (AP1).
- the 1 AP (AP1) receives the second station after SIFS from the transmission through the first link (Link1).
- STA2 may transmit an RTS frame as a receiver.
- the first station STA1 receives the RTS frame of which the second station STA2 is a receiver, and transmits the received RTS frame to the second station STA2.
- the second station STA2 performs CCA during PIFS. If the channel is idle during PIFS, the second station STA2 transmits a CTS-to-Self frame.
- the first AP AP1 may stop transmission to the first station STA1 during a time period during which the second station STA2 is expected to transmit a response to the RTS frame. Also, while the second station STA2 transmits a response to the RTS frame, the first station STA1 may transmit an ACK for the received transmission. In another specific embodiment, while the second station STA2 transmits a response to the RTS frame, the first station STA1 may also transmit a response to the RTS frame.
- FIG. 29 is for helping understanding of the description and may be used for transmission of control frames other than the RTS frame and the CTS-to-Self frame. Also, a time interval other than PIFS may be used.
- FIG. 30 shows that a multi-link device transmits an ACK according to an embodiment of the present invention.
- the station of the multi-link device may request a link to transmit an ACK to the station of the no-STR multi-link device. Specifically, the station of the multi-link device may request to transmit the ACK in a link different from that on which the transmission was performed.
- the first AP (AP1) of the STR multi-link device performs transmission (Tx(#2)) to the first station (STA1) of the non-STR multi-link device. In this case, the first AP (AP1) requests to transmit an ACK for the transmission (Tx(#2)) to the second link (Link2).
- the station may set an ACK policy with an implicit BAR so as not to transmit an immediate response to the transmission.
- the station may set the ACK policy for transmission to BlockAckReq.
- BlockAckReq since BlockAckReq must be transmitted in order to transmit Block ACK, a channel access burden and transmission delay may occur. Therefore, a new ACK policy for a multi-link device may be required.
- One station of the multi-link device may transmit an ACK for transmission received by another station included in the multi-link device, such as an ACK for transmission received by the station.
- Such ACK transmission may be referred to as ML (multilink)-ACK.
- ML-ACK may be configured as an ACK policy.
- the first AP (AP1) sets the ACK policy of the transmission (Tx(#2)) to ML-ACK. After receiving the transmission (Tx(#2)), the first station STA1 does not transmit an ACK to the first AP AP1.
- the second station (STA2) completes receiving the transmission transmitted from the second AP (AP2), and sends an ACK for the transmission from the first AP (AP1) to the second AP (AP2) and the transmission from the second AP (AP2).
- ACK is transmitted together.
- the non-STR multi-link device includes a first station (STA1) and a second station (STA2) as well as a third station (STA3), and the STR multi-link device includes a first AP (AP1) and a second AP (AP2). In addition, it may include a third AP (AP3).
- the ACK policy of transmission from the second AP (AP2) to the second station (STA2) may also be set to ML-ACK.
- the third station (STA1) sends the first AP ( ACK for transmission from AP1) to the first station (STA1), ACK for transmission from the second AP (AP2) to the second station (STA2), and from the third AP (AP3) to the third station (STA3)
- An ACK for transmission may be transmitted to the third AP (AP3).
- the ACK policy may also be set to BlockAck instead of ML-ACK.
- the ACK policy may be set to No Ack instead of ML-ACK.
- the multi-link device While the multi-link device transmits traffic, the number of links for which a transmission opportunity is obtained may increase. In this case, the multi-link device may transmit the traffic intended to be transmitted through the link on which the transmission opportunity is acquired first, through the link on which the transmission opportunity is acquired later. In this case, the NAV set in the link in which the multi-link device first acquires the transmission opportunity may be set larger than the NAV required to transmit the traffic. If the multi-link device is set to be larger than the NAV required to transmit traffic on the link that first acquired the transmission opportunity, the multi-link device first completes the transmission on the link that acquired the transmission opportunity and then transmits the CF-END frame to obtain the NAV. can be reset.
- the first station of the non-STR multi-link device In order for the first station of the non-STR multi-link device to receive the sync PPDU described above, it must determine whether the second station having a non-STR relationship with the first station starts to receive the sync PPDU. In addition, the first station must continuously perform preamble detection (PD). Considering that the first station receiving the sync PPDU is prohibited from accessing the channel by performing reception of another station of the non-STR multi-link device, this operation of the first station may be unreasonable. Accordingly, the first station may enter the power saving state within a predetermined condition. The sync PPDU may be transmitted within the previously configured TXOP. Therefore, the performance gain that can be obtained by receiving the sync PPDU may be determined according to the length of the remaining TXOP.
- PD preamble detection
- the first station may determine whether to abandon reception of the sync PPDU based on the length of the sync PPDU.
- the first station may enter a power saving state.
- This power saving operation may be referred to as inter-link TXOP power save (PS).
- the station entering the power saving state may wake up from the power saving state to receive a frame periodically transmitted from the AP, for example, a beacon frame, a TIM frame, and a DTIM frame.
- the station entering the power saving state in the inter-link TXOP PS may wake up from the power saving state.
- the above-described TXOP may be changed to a period indicated through the length field of the signaling field of the PPDU and the Duration field of the MAC frame.
- the station may determine the time occupied by the PPDU based on the period indicated through the length field and the Duration field of the MAC frame.
- the non-AP multi-link device may signal information on whether sync PPDU reception is supported and a condition for supporting sync PPDU to the AP multi-link device.
- the AP multi-link device may signal whether to support transmission of the AP multi-link long-term sync PPDU to the non-AP multi-link device.
- the multi-link device may signal whether to support the sync PPDU for each multi-link device.
- the AP multi-link device may signal whether sync PPDU transmission is supported for each AP multi-link device.
- the multi-link device may signal whether sync PPDU is supported for each station.
- the AP multi-link device may signal whether sync PPDU transmission is supported for each AP included in the AP multi-link device.
- an AP multi-link device including a first AP, a second AP, and a third AP may indicate that the first AP supports sync PPDU transmission and that the second AP and the third AP do not support sync PPDU transmission.
- the station of the non-AP multi-link device prevents other stations of the non-AP multi-link device from receiving it.
- the power saving state of the inter-link PS described above may be entered. This is because the AP multi-link device associated with the non-AP multi-link device cannot transmit a sync PPDU. In this case, the station of the non-AP multi-link device receives a PPDU from another station of the non-AP multi-link device. It is possible to determine the length of time for maintaining the power saving state based on the length of .
- Whether to support transmission or reception of the above-described sync PPDU may be determined according to an operation policy as well as hardware performance. Accordingly, whether transmission support or reception support of the sync PPDU is supported may be signaled through information about an operating mode as well as information about performance. A method of signaling support for transmission or reception of a sync PPDU will be described in detail with reference to FIG. 31 .
- 31 shows an element field indicating information on sync PPDU reception support or transmission support according to an embodiment of the present invention.
- the information indicating whether sync PPDU transmission is supported may be included in the element indicating the capability of the station.
- an element indicating the capability of the station is referred to as a capability element.
- a field of information indicating whether sync PPDU transmission is supported in the Capability element is referred to as a Supporting Sync PPDU Tx subfield.
- the Capability element may be a Multi-Link element, which is an element indicating a multi-link-related capability.
- the Capability element may be an EHT Capability element, which is an element indicating EHT-related capabilities. 31( a ) shows an example of a Capability element.
- the Supporting Sync PPDU Tx may indicate that the station or multi-link device indicated by the Supporting Sync PPDU Tx subfield supports the transmission of the sync PPDU.
- the Supporting Sync PPDU Tx may indicate that the station or multi-link device indicated by the Supporting Sync PPDU Tx subfield does not support the transmission of the sync PPDU.
- the Supporting Sync PPDU Tx subfield may signal information other than information irrelevant to whether sync PPDU transmission is supported or may be used as a reserved field.
- information indicating whether sync PPDU reception is supported may be included in an element indicating operation-related information of a station.
- an element indicating operation-related information of a station is referred to as an operation element.
- a field of information indicating whether to support sync PPDU reception in the operation element is referred to as a Supporting Sync PPDU Rx Disable subfield.
- 31(b) shows an example of an Operation element. When the value of the Supporting Sync PPDU Rx Disabled subfield is 1, it may indicate that reception of the sync PPDU is not desired.
- the Supporting Sync PPDU Rx Disabled subfield may indicate that the station transmitting the Supporting Sync PPDU Rx Disabled subfield does not want to wait for the sync PPDU.
- the second station of the multi-link device may not perform PD and CCA while the first station of the multi-link device performs reception.
- the AP multi-link device connected to the multi-link device that transmitted the Supporting Sync PPDU Rx Disabled subfield does not simultaneously transmit PPDUs to multiple stations of the multi-link device that transmitted the Supporting Sync PPDU Rx Disabled subfield.
- the PPDU may be a SU PPDU, a Full BW MU PPDU, or an OFDMA MU PPDU transmitted in any one of a non-HT PPDU, HT PPDU, VHT PPDU, HE PPDU, and EHT PPDU format.
- the AP multi-link device should not transmit a response, for example, a frame requesting an immediate response.
- the response request frame may include at least one of RTS, Multi-User RTS (MU-RTS), trigger frame, and Block Ack Request (BAR).
- the operation element may include information related to a minimum length of a sync PPDU that can be received by a station or a multi-link device that has transmitted the operation element.
- a subfield indicating information related to the minimum length of the sync PPDU is referred to as a Remaining TXOP Threshold subfield.
- the Remaining TXOP Threshold subfield may indicate time.
- the Remaining TXOP Threshold subfield may be indicated in units of us, ms, or symbols.
- a multi-link device connected to the multi-link device that transmitted the Remaining TXOP Threshold subfield is not allowed to transmit a sync PPDU shorter than the length indicated by the Remaining TXOP Threshold subfield to the multi-link device or station that transmitted the Remaining TXOP Threshold subfield. it may not be
- the Remaining TXOP Threshold subfield when the Remaining TXOP Threshold subfield is set to a predetermined value, it may indicate that the multi-link device or station that has transmitted the Remaining TXOP Threshold subfield does not support the reception of the sync PPDU.
- the predetermined value may be a value indicating a time greater than the maximum time that the Remaining TXOP Threshold subfield may indicate. In another specific embodiment, the predetermined value may be 0. When these embodiments are applied, the Sync PPDU Rx Disable subfield in the Operation element may be omitted.
- the Sync PPDU Rx Disable subfield and the Remaining TXOP Threshold subfield can be signaled through the Operation element in the above-described embodiments.
- the Sync PPDU Rx Disable subfield and the Remaining TXOP Threshold subfield may be signaled through elements other than the Operation element or signaling information.
- An embodiment in which the inter-link TXOP power saving mode is performed according to the signaling described with reference to FIG. 31 through FIGS. 32 to 34 will be described.
- the second station of the non-STR multi-link device may enter a power saving state while the first station of the non-STR multi-link device is performing reception. can In this case, the second station may maintain the power saving state until the end of the TXOP indicated by the PPDU received by the first station.
- the time at which the second station is expected to receive a frame periodically transmitted from the AP may be before the end time of the TXOP indicated by the PPDU received by the first station. In this case, the second station may wake up from the power saving state before the end of the TXOP indicated by the PPDU received by the first station.
- the frame periodically transmitted from the AP may include at least one of a beacon frame, a TIM frame, and a DTIM frame.
- the second station may maintain the power saving state even after the end of the TXOP indicated by the PPDU received by the first station. Specifically, the second station may determine whether to maintain the power saving state even after the end of the TXOP indicated by the PPDU received by the first station based on information received from the AP connected to the second station. In this case, the information received from the AP connected to the second station may be NAV-related information. Also, the information received from the AP connected to the second station may be operation information of the AP to which the first station is connected.
- the first AP of the AP multi-link device When the NAV set by the second AP of the AP multi-link device that is transmitting to the second station of the non-AP multi-link device has not expired, the first AP of the AP multi-link device indicates that it does not want to receive the sync PPDU. Information on the expected end time of transmission or reception of the first AP and the expected expiration time of the NAV may be transmitted to the first station of the signaling non-AP multi-link device. If the NAV set by the second AP of the AP multi-link device that is transmitting to the second station of the non-AP multi-link device has not expired, the second AP may include transmitting or receiving a PPDU from any one station.
- the NAV set by the second AP of the AP multi-link device that is transmitting to the second station of the non-AP multi-link device has not expired, the NAV is set to the second AP by the PPDU not transmitted by the second station.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link1) and a second AP (AP2) operating in a second link (Link2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link1 and a second station STA2 operating on a second link Link2.
- the non-STR non-AP multi-link device signals that it does not want to receive a sync PPDU.
- the first AP (AP1) performs transmission to the first station (STA1).
- the second station STA2 maintains the power saving state until the end of the TXOP indicated by the PPDU transmitted by the first AP AP1 to the first station STA1 .
- the first station of the non-STR multi-link device indicates that the remaining duration of the TXOP indicated by the PPDU being received by the first station of the non-STR multi-link device is indicated by the Remaining TXOP Threshold subfield transmitted by the non-STR multi-link device. If the length is equal to or shorter than the length, it can enter the power saving state of the inter-link TXOP. ⁇ At this time, before entering the power saving state, that is, the remaining duration of the TXOP indicated by the PPDU being received by the first station is the non-STR multi When the length indicated by the Remaining TXOP Threshold subfield transmitted by the link device is greater than the length indicated by the link device, the second station may receive the sync PPDU transmitted by the second station.
- the second station may receive the sync PPDU.
- the second station performs PD, and may determine whether the intended recipient of the received PPDU is the second station. Specifically, the second station may determine whether the AID indicated by the signaling field of the PPDU or the RA of the MAC frame included in the PPDU indicates the second station.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link1) and a second AP (AP2) operating in a second link (Link2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link1 and a second station STA2 operating on a second link Link2.
- the non-STR non-AP multi-link device signals that it wants to receive a sync PPDU. In this case, the non-STR non-AP multi-link device also signals the minimum TXOP length, 'a', required for sync PPDU reception.
- the first AP (AP1) transmits to the first station (STA1), and the second station (STA2) waits for reception of the sync PPDU.
- the second station (STA2) enters the inter-link TXOP power saving state.
- the non-STR multi-link device may enter an inter-link TXOP sleep state. In this case, the station may determine that a PPDU for which the station is not an intended recipient is not a sync PPDU. In addition, the station detects transmission of a PPDU other than the sync PPDU in the BSS operated by the AP connected to the station of the non-STR multi-link device in the power-saving state even if the minimum TXOP signaled by the station remains. The station of may enter the inter-link TXOP power saving state.
- the STR AP multi-link device includes a first AP (AP1) operating in a first link (Link1) and a second AP (AP2) operating in a second link (Link2).
- the non-STR non-AP multi-link device includes a first station STA1 operating on a first link Link1 and a second station STA2 operating on a second link Link2.
- the non-STR non-AP multi-link device signals that it wants to receive a sync PPDU. In this case, the non-STR non-AP multi-link device also signals the minimum TXOP length, 'a', required for sync PPDU reception.
- the first AP (AP1) transmits to the first station (STA1), and the second station (STA2) waits for reception of the sync PPDU.
- the second station STA2 detects that a PPDU other than the sync PPDU is transmitted from the BSS belonging to the second station.
- the TXOP of the PPDU transmitted by the first AP (AP1) to the first station (STA1) is greater than 'a', the second station (STA2) enters the inter-link TXOP power saving state.
- the multi-link device may operate adaptively considering that the first station of the non-STR multi-link device performs transmission and the second station becomes blind. Specifically, when the multi-link device determines that the station of the non-STR multi-link device is in the blind state, the multi-link device may stop transmission to the station of the non-STR multi-link device. Also, the station of the non-STR multi-link device may enter a doze state based on the operations of other stations of the non-STR multi-link device, for example, transmission and reception. Through this, it is possible to solve a problem that may occur when the operation of one station of the non-STR multi-link device is restricted due to the operation of another station.
- the non-STR multi-link device different stations included in the non-STR multi-link device cannot simultaneously perform reception and transmission due to intra-device interference.
- different stations included in the non-STR multi-link device cannot simultaneously perform reception and transmission due to limitations in the hardware configuration of the non-STR multi-link device.
- the second station of the non-STR multi-link device may be restricted from using the transceiver.
- a non-STR multi-link device may support only one PPDU processing. In this case, when the first station of the non-STR multi-device performs transmission or reception, the second station of the non-STR multi-device cannot perform transmission or reception.
- a multi-link device including a plurality of stations operating in a plurality of links, but not supporting simultaneous transmission or reception of the plurality of stations is referred to as a single radio multi-link device. Therefore, when any one station of the single radio multi-link device performs transmission/reception, the other station of the single radio multi-link device cannot perform transmission/reception.
- the operation of the multi-link device as a single radio multi-link device may be in accordance with a hardware constraint or an operation mode definition as described above.
- a single radio multi-link device may refer to a multi-link device in which an operation of a station is restricted due to hardware restrictions as well as a multi-link device in which an operation of a station is restricted according to the definition of an operation mode. Therefore, the single radio multi-link device of the present specification supports simultaneous transmission or reception of a plurality of stations of the multi-link device, but does not support simultaneous transmission or reception of a plurality of stations of the multi-link device under certain conditions. It may include a multi-link device that does not In this case, the specific condition may include a specific time point.
- the multi-link device may operate as a single radio multi-link device according to an operation mode. For example, when a specific mode is deactivated, the multi-link device may transmit or receive on a plurality of links, and when a specific mode is activated, transmit or receive only on a single link among a plurality of links in a specific time interval. In this case, when a specific mode is deactivated, the multi-link device may transmit or receive in a plurality of stations, and when a specific mode is activated, only a single station among the plurality of stations may transmit or receive in a specific time interval. In this case, the specific time period may include a time during which the multi-link device performs frame exchange in any one link.
- the specific time period may be from when the multi-link device receives an initial control frame for initiating frame exchange on one link to the end of the corresponding frame exchange.
- the specific mode may be referred to as an enhanced multi-link single radio (EMLSR) mode.
- EMLSR which is a plurality of links to which the EMLSR mode is applied While the multi-link device performs frame exchange on the first link of the link, the multi-link device does not transmit and receive on the second link of the EMLSR link.
- the specific mode is set to EMLMR (enhanced multi-link multi -radio) mode.
- EMLMR enhanced multi-link multi -radio
- the operation of the multi-link device is the same as that of the multi-link device in the EMLSR mode. can be the same.
- some links among a plurality of links in which the multi-link device operates may operate without limitation due to the EMLSR mode.
- the link to which the EMLSR mode is applied may be a part of the link on which the multi-link device operates.
- the EMLSR mode or the EMLMR mode may be applied only to the first link and the second link. Therefore, when the multi-link device performs transmission or reception on the first link in a specific time interval of the EMSLR mode, the multi-link device cannot perform transmission or reception on the second link. In this case, the multi-link device may transmit or receive without limitation according to the EMLSR mode in the third link.
- a link to which the EMLSR mode can be applied such as the first link and the second link
- an EMLSR link a link to which the EMLMR mode can be applied
- an EMLMR link a link to which the EMLMR mode can be applied
- performing transmission or reception using the RF chain of a specific station results in switching of transmission, reception or monitoring capabilities in the link in which the specific station operates. Therefore, in the following description, the embodiments of the present invention applied in relation to the EMLSR mode may be equally applied in relation to the EMLMR mode without special mention.
- the embodiments related to the operation of the non-STR multi-link device described above may also be applied to the operation of a single radio multi-link device.
- the above-described embodiments regarding the operation of a station performing transmission/reception with a non-STR multi-link station may also be applied to an operation of a station performing transmission/reception with a station of a single radio multi-link device. For example, when the station determines that transmission to a single radio multi-link device in the first link has failed due to transmission or reception of a single radio multi-link device in the second link, the station determines the CW of channel access performed in the first link may not increase. Specifically, the station may apply the embodiment described with reference to FIG. 14 .
- the method in which the station determines that transmission to a single radio multi-link device in the first link has failed due to transmission or reception of a single radio multi-link device in the second link is a method in which the station transmits to a station of a non-STR multi-link It may be similar to a method of determining whether the non-STR multi-link device has failed due to an operation restriction.
- 35 shows a connection between a single radio multi-link device and an AP multi-link device according to an embodiment of the present invention.
- the PHY backend refers to a digital processor of a physical layer including a processor for encoding and decoding a PPDU.
- the PHY front-end refers to the analog baseband circuit including the RF chain.
- a plurality of stations of a single radio multi-link device operate on different links. Multiple stations may share a PHY backend. In this case, when any one station transmits a PPDU, the PHY backend is used for encoding the PPDU. Therefore, at this time, the remaining stations of the plurality of stations cannot use the PHY backend. Therefore, a single radio multi-link device includes a plurality of stations operating on different links, but can transmit or receive only on one link at a time.
- a single radio multi-link device may perform channel access in a plurality of links.
- a single radio multi-link device may perform monitoring on a plurality of links.
- a single radio multi-link device may perform channel access on a plurality of links.
- monitoring may include channel sensing.
- the channel sensing may include at least one of clear channel assessment (CCA) and preamble detection (PD).
- CCA clear channel assessment
- PD preamble detection
- a single radio multi-link device can reduce channel access delay. Specifically, even if the first station of a single radio multi-link device fails to perform channel access due to channel occupation of another wireless communication device performed on the first link, the second station of the single radio multi-link device back-offs in the second link. procedure can be performed.
- the single radio multi-link device may be a multi-link device operating in the EMLSR mode as described above.
- the PHY front-end of a single radio multi-link device may support channel monitoring independently from the PHY back-end.
- the PHY front end of a single radio multi-link device may support decoding of the preamble of the PPDU independently from the PHY back end for the PD.
- the PHY front-end of a single radio multi-link device may support reception of a frame transmitted through a low MCS independently from the PHY back-end.
- the frame transmitted through the low MCS may include at least one of an RTS frame and an MU-RTS frame.
- the PHY front-end may include a MAC processor.
- the processing power of the PHY backend may be intensively utilized for encoding and decoding of data frames.
- the AP multi-link device includes a first AP (AP1) and a second AP (AP2).
- a single radio multi-link device includes a first non-AP station (Non-AP STA1) and a second non-AP station (Non-AP STA2).
- a first AP (AP1) is connected to a first non-AP station (Non-AP STA1) in a first link (Link1)
- a second AP (AP2) is connected to a second non-AP station in a second link (Link2) (Non-AP STA2) is connected.
- each of the first Non-AP station (Non-AP STA1) and the second Non-AP station (Non-AP STA2) independently perform channel access using the PHY frontend.
- a single radio multi-link device may be used for MIMO transmission using the RF chain of stations not participating in transmission or reception. Specifically, when the first station of a single radio multi-link device acquires a channel access opportunity, the first station uses not only the RF chain used by the first station but also the RF chain used by the second station of the single radio multi-link device. Thus, MIMO transmission can be performed. This will be described with reference to FIG. 36 .
- a first station STA1 of a single radio multi-link device operates on a first link (Link 1)
- a second station STA2 of a single radio multi-link device operates on a second link (Link 2). It works.
- the first station STA1 performs channel access on a first link Link 1
- the second station STA2 performs channel access on a second link Link 2 .
- the first station STA1 succeeds in accessing the channel in the first link Link 1
- the first station STA1 transmits the RF chain used for channel access in the first link Link 1 as well as the second station STA2.
- 2x2 MIMO transmission is performed on the first link (Link 1) using the RF chain used for channel access in the second link (Link 2).
- a single radio multi-link device when the RF chain operating in the second link is changed to operate in the first link, a single radio multi-link device cannot perform monitoring and channel access in the second link.
- the single radio multi-link device waits for a predetermined time and then performs channel access in the second link.
- channel access of a single radio multi-link device in the second link may be restricted for a predetermined time from when the RF change is completed.
- a single radio multi-link device may perform channel access in the second link after waiting for a predetermined time from when the RF change is completed.
- the channel access may include a backoff procedure.
- the predetermined time may be a predetermined time applied when a restriction on channel access is required due to a time when channel monitoring is not possible.
- the predetermined time may be NAVSyncdelay.
- a single radio multi-link device may perform a backoff procedure after waiting for NAVSyncdelay. This is because there is a high probability that a single radio multi-link device cannot detect transmission of another wireless communication terminal being performed in the second link due to a period during which channel monitoring is not performed.
- a delay time for starting the operation of the RF chain may be required. Therefore, a single radio multi-link device may perform channel access in consideration of the delay time of the RF chain change. This will be described with reference to FIG.
- RF chain change changing the RF chain operating in one link to operate in another link
- a change in the link may indicate a change in the RF chain supported by the link.
- the first link supports the use of a plurality of RF chains and supports the use of one RF chain
- the second link does not support the use of one RF chain and supports the use of one RF chain. In this case, it may be referred to as a change in the RF chain.
- the transmission, reception, or monitoring capability may be changed in the link to which the EMLSR mode or the EMLMR mode is applied. Accordingly, the RF chain of the link to which the EMLSR mode or the EMLMR mode is applied may be re-established. In this way, even when the link is switched in the EMLSR mode or the EMLMR mode, the above-described channel access restriction may be applied.
- link switching is performed in a link to which EMLSR mode or EMLMR mode is applied, channel access of stations to which mode switching is applied among stations of a multi-link device may be restricted for a predetermined time from a reconfiguration time.
- the predetermined time may be NAVSyncDelay or MediumSyncDelay. Even if a predetermined time has not elapsed, when a frame capable of setting the NAV is received, the channel access restriction of the multi-link device may be released. Also, the predetermined time may be a time indicated by the NAVSyncDelay parameter. In these embodiments, even before a predetermined time elapses from the time when link switching is completed, that is, when the monitoring capability is recovered, the station can start exchanging frames by transmitting a control frame for setting the NAV for setting the NAV.
- the control frame for setting the NAV may be at least one of an RTS frame and an MU-RTS frame.
- switching of a link may include recovering after losing all or part of the transmit, receive, or monitor capability of the link.
- the case in which the transmission, reception or monitoring capability of the EMLSR mode or the link to which the EMLMR mode is applied is changed may include a case in which the frequency band or the center frequency of the RF chain is changed.
- the channel access restriction of the multi-link device may be that transmission of the multi-link device is prohibited and the multi-link device performs CCA.
- a station communicating with a single radio multi-link device using MIMO may be a station of the multi-link device.
- a station communicating with a single radio multi-link device using MIMO may be an AP included in the multi-link device.
- a station communicating with a single radio multi-link device using MIMO may be a station included in the multi-link device.
- the station included in the multi-link device may be an AP.
- what has been described as an operation of a station of a multi-link device may represent an operation of a multi-link device.
- FIG. 37 shows an operation of a single radio multi-link device performing channel access in consideration of a delay time of an RF chain change according to an embodiment of the present invention.
- a single radio multi-link device may change the RF chain before it is expected to succeed in channel access. Specifically, a single radio multi-link device may change the RF chain before a time set based on the delay time of the RF chain change from the time when channel access is expected to succeed. For example, a single radio multi-link device may change the RF chain at a point in time as early as the delay time of the RF chain change from the time when channel access is expected to succeed.
- a first station STA1 of a single radio multi-link device operates on a first link (Link 1)
- a second station STA2 of a single radio multi-link device operates on a second link (Link 2). It works.
- the first station STA1 performs channel access on a first link Link 1
- the second station STA2 performs channel access on a second link Link 2 .
- the first station STA1 succeeds in accessing the channel in the first link Link 1
- the first station STA1 transmits the RF chain used for channel access in the first link Link 1 as well as the second station STA2.
- 2x2 MIMO transmission is performed on the first link (Link 1) using the RF chain used for channel access in the second link (Link 2).
- a single radio multi-link device changes the RF chain at a time as early as the delay time of the RF chain switching (RF chain switching delay) from the time point (Expected Tx time) expected to succeed in channel access. .
- the single radio multi-link device may start exchanging RTS frames/CTS frames.
- the single radio multi-link device may transmit a CTS-to-Self frame.
- a single radio multi-link device may transmit a frame having a relatively short length instead of a CTS-to-Self frame.
- a single radio multi-link device starts transmission by exchanging RTS frames/CTS frames in a first link (Link 1).
- a single radio multi-link device may perform transmission or reception by changing the RF chain as described with reference to FIGS. 36 to 37 .
- a single radio multi-link device can transmit or receive without changing the RF chain.
- a single radio multi-link device can choose to change the RF chain.
- a single radio multi-link device may indicate whether to use the RF chain of another link when performing MIMO communication in the corresponding link in the MIMO Rx support subfield of the Operation element. For example, when a single radio multi-link device sets the value of the MIMO Rx support subfield of the Operation element to 1, the MIMO Rx support subfield is less than or equal to the value of the Max Rx spatial stream subfield of the Operation element spatial (spatial) It may indicate that MIMO reception can be performed using a stream. In this case, the station performing MIMO transmission to a single radio multi-link device should perform MIMO transmission using the number of spatial streams less than or equal to the value of the Max Rx spatial stream subfield of the operation element.
- the format of the operation element may be as shown in FIG. 38(a).
- a single radio multi-link device may signal the time required to change the RF chain in the Capability element.
- the switching latency subfield of the capability element may indicate the time required to change the RF chain.
- a station performing MIMO transmission to a single radio multi-link device should perform MIMO transmission in consideration of the time required to change an RF chain.
- a station performing MIMO transmission to a single radio multi-link device may start MIMO transmission after a time required to change an RF chain from the initial transmission to a single radio multi-link device.
- the format of the capability element may be as shown in FIG. 38(a).
- a station that intends to transmit to a single radio multi-link device may not be permitted to perform transmission on a link other than the first link. This is because a single radio multi-link device cannot perform reception on a link other than the first link while transmission or reception is performed on the first link. Specifically, not only during frame exchange in the first link, but also until a predetermined time elapses from when the single radio multi-link device completes the frame exchange sequence, the station that wants to transmit to the single radio multi-link device transmits the first It may not be permitted to perform a transmission on a non-link link.
- completion of the frame exchange sequence may be determined based on reception or transmission of the last frame of the frame exchange sequence.
- the frame exchange sequence may be performed on a link in which a plurality of RF chains are available.
- the frame exchange sequence may be performed using MIMO.
- the predetermined time may be determined based on the required time for changing the RF chain.
- the predetermined time may be a required time for changing the RF chain.
- the EMLSR mode of the multi-link device When the EMLSR mode of the multi-link device is activated, transmission and reception are possible only on a specific link among a plurality of links to which the EMLSR mode of the multi-link device is applied in a specific time interval. In addition, when the EMLMR mode of the multi-link device is activated, transmission and reception are enabled only on a specific link among a plurality of links to which the EMLMR mode of the multi-link device is applied in a specific time interval. In addition, as described above, when the transmission, reception or monitoring capability of the EMLSR mode or the link to which the EMLMR mode is applied is changed, the RF chain may be reconfigured.
- the EMLMR link or the EMLSR link may be limited to a link in which link switching, for example, an RF chain is reset.
- the predetermined time may be a delay time for link switching.
- the link switching may represent an operation for recovering the monitoring capability from the link that has lost the monitoring capability.
- the predetermined time may be set based on the time required for link switching, for example, RF chain change.
- a station or a multi-link device performing frame exchange with the multi-link device must be able to determine a link switching time.
- the station or multi-link device may determine the end time of the EMLMR mode or the EMLSR mode.
- the EMLMR mode and the EMLSR mode are collectively referred to as the EML mode.
- the EMLMR link and the EMLSR link are collectively referred to as an EML link.
- a timer may be set for a frame exchange end time in a second link that is one of the EML links.
- this timer is collectively referred to as an end-time timer.
- the station may set an end time timer based on the Duration/ID field of the frame received from the multi-link device entering the EML mode.
- the station may determine when the end time timer expires as the end time of frame exchange corresponding to the timer.
- the multi-link device to which the EML mode is applied may set a timer for the end time. In this case, the multi-link device may synchronize the end time timer and the end time timer of the station.
- the multi-link device may set an end time timer based on the Duration/ID field of the frame received from the AP.
- the frame exchange end time may be a time frame exchange is completed in the EML mode.
- the frame exchange end time may be the end time of the TXOP configured to protect the frame exchange in the EMLMR mode or the EMLSR mode.
- the station may determine the end time of the TXOP set for the frame exchanged when the EML mode is applied as the frame exchange end time.
- the termination of the TXOP may include a case in which the TXOP is terminated because a new backoff procedure must be invoked before the TXOP is completed. If neither TXOP holder nor TOXP responder can occupy the channel during (aSIFSTime + aSlotTime) within the TXOP, a new backoff procedure must be initiated.
- aSIFSTime indicates SIFS defined in 802.11, that is, 16us
- aSlotTime indicates a unit time for channel sensing in EDCA and DCF, that is, 9us.
- the station may determine when the institution indicated by the Duration/ID field of the frame transmitted in the EML link elapses as the frame exchange end time.
- the station may determine that the frame exchange ends when it is detected that the corresponding link is idle for a predetermined time after transmitting a response frame to the multi-link device in the EML link where the frame exchange is performed in the EML mode.
- the station may receive a frame that does not require an immediate response frame from the multi-link device. In this case, the station does not transmit a response frame. Therefore, when the station receives a frame that does not request a response frame from the multi-link device in the EML link where frame exchange is performed in the EML mode, when the corresponding link is detected to be idle for a certain period of time, it is determined as the frame exchange end time.
- the station when the station receives a frame requesting a response frame, the station transmits a response frame to the multi-link device in the EML link where frame exchange is performed in EML mode, and then when it is detected that the link is idle for a certain period of time may be determined as the frame exchange end time.
- the predetermined time may be PIFS + aRXPHYStartDelay.
- PIFS may be aSIFSTime + aSlotTime.
- aRXPHYStartDelay may be a delay time related to the time required for the MAC to recognize the fact after the PHY starts the Rx operation.
- the station may determine the time when the response frame is transmitted as the time when the PHY-TXEND.confirm primitive for the response frame occurs.
- the time when the station receives a frame that does not request a response frame may be a time when the PHY-RXEND.indication primitive is generated.
- the EML mode multi-link device must successfully receive the Tigger frame or TRS Control field included in the PPDU to perform the Ack response. If the multi-link device in EML mode does not successfully receive the Trigger frame or the TRS Control field, the multi-link device fails to transmit a response even if it receives a frame requesting a response frame. At this time, if the station does not retransmit the frame requesting an immediate response, the TXOP is terminated.
- the AP multi-link device transmits the initial control frame to the multi-link device to which the EML mode is applied during the RF switching change period of the multi-link device to which the EML mode is applied from the TXOP time set to protect the frames exchanged in the EML mode. Not permitted. That is, the AP multi-link device sends an initial control frame to the multi-link device to which the EML mode is applied after the RF switching change time of the multi-link device to which the EML mode is applied from the TXOP time set to protect the frames exchanged in the EML mode. can be transmitted
- the station may determine when the CF-End frame is received in the EML link in which the frame exchange is performed in the EML mode as the frame exchange end time. In this case, the station may determine that the CF-End frame has been received at the point in time when the PHY-RXSTART.indication primitive is generated due to the CF-End frame. In another specific embodiment, the station may determine that the CF-End frame has been received at the time when the PHY-RXEND.indication primitive is generated due to the CF-End frame. In another specific embodiment, the station may determine that aSIFSTime before the CF-End frame is received as the frame exchange end time.
- the station may determine that the CF-End frame has been received at the point in time when the PHY-RXSTART.indication primitive is generated due to the CF-End frame. In another specific embodiment, the station may determine that the CF-End frame has been received at the time when the PHY-RXEND.indication primitive is generated due to the CF-End frame.
- the station can set an end time timer.
- the station may reset the end-time timer, i.e. set to zero.
- the station may set the end time timer to a value less than 0.
- a value less than 0 may be a time corresponding to an air time of the CF-End frame.
- a station that intends to perform frame exchange with the multi-link device to which the EML mode is applied may immediately start exchanging a new frame upon receiving the CF-End frame.
- the transmission restriction due to link switching described above may be applied only to a link that has lost transmission, reception, or monitoring capability in the EML mode, for example, a link where frame exchange is not performed in the EMLSR mode. That is, transmission restrictions due to link switching may not be applied to a link that does not lose transmission, reception, or monitoring capability in the EML mode in the EML mode, for example, a link in which frame exchange is performed in the EMLSR mode. For example, when the EML link is the first link and the second link, the frame exchange is performed on the first link in the EML mode, and the frame exchange on the first link ends, the transmission restriction may be applied only to the second link. In addition, when link switching is performed, transmission restrictions may not be applied to the first link.
- the multi-link device that has performed link switching has lost its transmission, reception, or monitoring capability in the EML mode within a predetermined time from the end of the frame exchange, for example, a link on which frame exchange is not performed in the EMLSR mode. monitoring may need to be restored.
- the station for example, the AP of the AP multi-link device, loses transmission, reception, or monitoring capability in the EML mode after a predetermined time from the end of the frame exchange, for example, in the EML link in the EML link where frame exchange was not performed in the EMLSR mode.
- Frame exchange for a multi-link device to which is applied may be started.
- a station to which the EML mode is applied may transmit a frame indicating the end of frame exchange.
- the frame indicating the end of the frame exchange may be a CF-End frame.
- a station that has completed the frame exchange in the EML mode may transmit the CF-End frame before the TXOP configured for the frame exchange ends.
- the multi-link device that has received the CF-End frame may determine that the multi-link device that has transmitted the CF-End frame has completed frame exchange in the EMLSR mode or EMLMR mode.
- the station that wants to perform transmission to a single radio multi-link device in the frame exchange sequence immediately after the RF chain change transmits first in the frame exchange sequence based on the time required for the RF chain change of the single radio multi-link device.
- the format of the PPDU may be determined.
- the station that wants to perform transmission to a single radio multi-link device is the first (initial) in the frame exchange sequence based on the time required for the RF chain change of the single radio multi-link device. )
- the length of the padding used for PPDU transmission can be determined.
- the padding may be either padding of the physical layer or padding of the MAC layer.
- the station sets the padding of a packet transmitted to a single radio multi-link device having a relatively short RF chain change time to be shorter than that of a packet transmitted to a single radio multi-link device having a relatively large RF chain change time required.
- padding may be inserted into an initial control frame that is a control frame transmitted first in frame exchange in the EMLSR mode.
- the padding duration may be determined based on the time required for link switching.
- the multi-link device may insert a padding having a length equal to or longer than the length of the padding corresponding to a time equal to or greater than the difference between the time required for link switching and (2x SIFS + CTS_time) into the initial control frame.
- CTS_time represents an air time required to transmit the CTS frame.
- the multi-link device may insert a padding having a length equal to or longer than the length of the padding corresponding to the time obtained by subtracting (2x SIFS + CTS_time) from the link switching time into the initial control frame.
- the multi-link device may insert a padding having a length equal to or longer than the length of the padding corresponding to a time equal to or greater than the difference between the time required for link switching and the SIFS into the initial control frame.
- the multi-link device may insert padding having a length equal to or longer than the length of the padding corresponding to the time obtained by subtracting the SIFS from the link switching time into the initial control frame.
- the multi-link device supporting the EMLSR mode may signal the padding duration of the initial control frame to the counterpart multi-link device.
- the multi-link device supporting the EMLSR mode may signal the padding length of the initial control frame instead of the time required for link switching.
- the counterpart multi-link device may insert padding corresponding to a time longer than the signaled padding length into the initial control frame.
- the counterpart multi-link device may insert padding of the signaled padding length into the initial control frame.
- the multi-link device may secure time to set up the RF chain.
- a station that wants to perform MIMO transmission for a single radio multi-link device may start exchanging RTS frames/CTS frames at the start of transmission after changing the RF chain.
- the RTS frame can secure a time for changing the RF chain and protect the frame exchange thereafter. If it is determined that the change of the RF chain is not completed even after the RTS frame/CTS frame exchange, a station that intends to perform MIMO transmission for a single radio multi-link device may not perform MIMO transmission. In this case, a station that intends to perform MIMO transmission for a single radio multi-link device may perform transmission using a single spatial stream.
- a single radio multi-link device When a single radio multi-link device performs transmission or reception on one link, the single radio multi-link device cannot perform transmission or reception on a link different from the corresponding link. Therefore, when a single radio multi-link device performs transmission or reception on one link, a station operating on a link different from the corresponding link may be viewed as a blind state. Therefore, when a single radio multi-link device transmits or receives on one link, an AP that intends to transmit to a single radio multi-link device may not transmit to a station operating in a link different from that of the corresponding link. In this case, an AP that intends to perform transmission to a single radio multi-link device may stop transmission being performed to a station operating in a link different from that of the corresponding link.
- the AP performing transmission or stopping transmission to the station of the single radio multi-link device is the CW of the backoff procedure used for channel access for transmission. may not increase. Thereafter, when a single radio multi-link device attempts to transmit again to a corresponding station, a backoff counter may be acquired in the previously used CW. Accordingly, a station that has performed or stopped transmission to a station of a single radio multi-link device may not increase the CW of a backoff procedure used for channel access when a predetermined condition is satisfied.
- the predetermined condition may be that the station determines that any one of the stations of a single multi-link device performs transmission or reception according to the above-described embodiment.
- the station determines that any one of the stations of the single multi-link device performs transmission can do.
- the station may determine the station transmitting the PPDU based on the identifier of the station transmitting the PPDU indicated by the signaling field of the PPDU.
- the station may determine which one of the stations of the single multi-link device is indicated by the STA-ID of the User field of the HE PPDU.
- the station may determine which one of the stations of the single multi-link device is indicated by the STA-ID of the User field of the EHT PPDU.
- the station may determine which one of the stations of the single multi-link device is indicated by the TA field of the MAC frame included in the PPDU.
- the MAC frame may be any one of MSDU, MPDU, and A-MPDU. This may be similar to the embodiments applied to the transmission for the non-STR multi-link device described above with reference to FIG. 19 .
- the CW described above may indicate the CW of an AC used for channel access.
- the station that has performed transmission to another station of the single radio multi-link device is retry
- the counter may not be incremented.
- the retry counter may include at least one of a long retry counter and a short retry counter.
- the above-described embodiment regarding maintaining the size of CW may not be applied.
- the station that transmitted the MU PPDU increases the size of the CW. can do it
- the station transmitting the MU PPDU may increase the value of the CW to the next larger value among the values that the CW value may have.
- the station transmitting the MU PPDU may maintain the value of the CW as the same value.
- a single radio multi-link device includes a first station STA1 operating in a first link Link 1 and a second station STA2 operating in a second link Link 2 .
- the station To perform transmission to the first station STA1 using MIMO, the station succeeds in channel access in the first link Link 1 and transmits an RTS frame to the first station STA1.
- the first station STA1 transmits a CTS frame in response to the RTS frame.
- the RF chain change of a single radio multi-link device is completed, and a PPDU is received using 2x2 MIMO.
- the single radio multi-link device changes the RF chain
- the second station waits for NAVSyncdelay from when the RF chain is changed and then the second link (Link 2) ) to initiate channel access.
- a single radio multi-link device may perform MIMO by changing a link on which an RF chain operates.
- the link on which the RF chain operates is changed, it is necessary to learn about the RF characteristics in the changed link before MIMO communication.
- a single radio multi-link device may perform channel estimation using an NDP sounding protocol.
- a beamformer transmits an NDP announcement (NDPA) and then an NDP.
- NDPA NDP announcement
- the interval between NDPA and NDP is SIFS.
- the station receiving the NDPA indicates the station in the STA User Info list field of the NDPA
- the station receives the NDP and then transmits CSI (channel state information) feedback measured when the NDP is received to the beamformer.
- CSI channel state information
- an RTS frame/CTS frame exchange may be performed before the NDP sounding protocol is performed.
- a single radio multi-link device and a station desiring to start an NDP sounding protocol may transmit an RTS frame before transmitting an NDPA frame.
- an NDP sounding protocol initiating station a single radio multi-link device and a station desiring to initiate an NDP sounding protocol.
- the NDP sounding protocol initiating station may protect the NDP sounding sequence.
- the NDP sounding protocol initiation station may perform an exchange procedure with a MU-RTS frame/CTS frame instead of an RTS frame/CTS frame exchange procedure.
- the NDP sounding protocol initiating station may perform an MU-RTS frame and other types of trigger frames and response exchanges for trigger frames instead of the MU-RTS frame/CTS frame exchange procedure.
- the NDP sounding protocol initiation station may transmit an MU-RTS frame, a trigger frame of a different type from the MU-RTS frame, and an NDPA frame in a predetermined PPDU format.
- the predetermined PPDU format may be at least one of a non-HT format and an HT format.
- the NDP sounding protocol initiating station may transmit an MU-RTS frame, a trigger frame of a different type from the MU-RTS frame, and an NDPA frame at a data rate or less at a predetermined data rate.
- the NDP sounding protocol initiating station may adjust the length of the NDP sound sequence based on the required time for changing the RF chain.
- the NDP sounding protocol initiating station is a single radio multi-link device with a relatively short duration of RF chain change, and a single radio multi-link device with a relatively longer duration of RF chain change than when exchanging an NDP sounding sequence. A longer NDP sounding sequence can be used when exchanging sounding sequences.
- the NDP sounding protocol initiation station may adjust the length of the NDP sounding sequence by omitting a part of the NDP sounding sequence.
- the NDP sounding protocol initiation station may adjust the length of the NDP sounding sequence by adjusting padding of frames exchanged in the NDP sounding sequence.
- the NDP sounding protocol initiating station may transmit an additional frame in the NDP sounding sequence to adjust the length of the NDP sounding sequence.
- the padding may be padding of the physical layer.
- the padding may be padding of the MAC layer. Therefore, in embodiments to be described later, the padding may be the padding of the physical layer or the padding of the MAC layer.
- the NDP sounding protocol initiating station when the NDP sounding protocol initiating station performs the NDP sounding protocol with a plurality of single radio multi-link devices, the NDP sounding protocol initiating station has the longest duration among the RF chain changes of the plurality of single radio multi-link devices. Based on this, the length of the NDP sounding sequence may be adjusted. A method for adjusting the length of the NDP sounding sequence will be described with reference to FIGS. 40 to 42 .
- FIG. 40 shows that a station and a single radio multi-link device perform an NDP sounding process according to an embodiment of the present invention.
- the NDP sounding protocol initiation station may adjust the length of the NDP sounding sequence by adjusting the padding of frames exchanged in the NDP sounding sequence.
- the NDP sounding protocol initiating station may adjust the length of the NDP sounding sequence by inserting padding into the RTS frame.
- the NDP sounding protocol initiating station may insert padding into the RTS frame.
- the NDP sounding protocol initiating station may transmit an MU-RTS frame instead of the RTS frame. In this case, the NDP sounding protocol initiation station may insert padding into the MU-RTS frame.
- the NDP sounding protocol initiating station determines that the RF chain change is not completed after a time elapsed by adding 2 X SIFS to the length of the CTS frame from the RTS frame reception completion point of a single radio multi-link device. It can be determined whether the RF chain change cannot be completed even after the /CTS frame exchange.
- the RTS reception completion time is the transmission start time of the PPDU including the RTS frame, the time when the physical layer header of the PPDU is transmitted to the RTS frame, the transmission completion time of the PPDU including the RTS frame, and the RTS frame or A including the RTS frame - It may be one of the MPDU transmission completion times.
- FIG. 40( a ) shows that an NDPA frame, an NDP frame, and a feedback frame are exchanged after an RTS frame/CTS frame exchange according to the embodiment described above.
- the NDP sounding protocol initiating station performs MIMO transmission based on the received feedback frame.
- the NDP sounding protocol initiating station may omit transmission of the NDPA frame in the NDP sounding sequence.
- the NDP sounding protocol initiating station and the single radio multi-link device may negotiate to perform the NDP sounding protocol without NDPA frame transmission. Therefore, a station of a single radio multi-link device can wait for NDP reception without receiving a NAPA frame.
- a station of a single radio multi-link device may use a capability element to signal that it can receive NDP without NDPA reception.
- the station of a single radio multi-link device may signal that it can receive the NDP frame without receiving the NDPA frame by setting the NDPA compression support subfield of the Capability element to 1.
- the station of the radio multi-link device may set the NDPA compression support subfield of the Capability element to 0 to signal that it cannot receive the NDP frame without receiving the NDPA frame.
- the NDP sounding protocol initiating station may decide whether to omit the NDPA frame transmission. In this case, the NDP sounding protocol initiating station may omit transmission of the NDPA frame from the NDP sounding sequence performed to the single radio multi-link device that has received that the NDP frame can be received without receiving the NDPA frame.
- the embodiment of omitting the NDPA frame transmission in the NDP sounding sequence can be applied only when the NDP sounding protocol initiating station transmits the NDP to one station.
- FIG. 40(b) shows that an NDP frame and a feedback frame are exchanged without an NDPA frame after the RTS frame/CTS frame exchange according to the embodiment described above.
- the NDP sounding protocol initiating station performs MIMO transmission based on the received feedback frame.
- the NDP sounding sequence since the NDP sounding sequence includes the control frame exchange before the NDPA frame, the NDP frame, and the feedback frame exchange, an excessive overhead may occur. In addition, even if NDPA transmission is omitted, excessive overhead may occur. In order to reduce excessive overhead, an implicit feedback beamforming sounding sequence may be performed. This will be described with reference to FIG. 41 .
- 41 shows that a station and a single radio multi-link device perform a feedback beamforming sounding sequence according to an embodiment of the present invention.
- the frame exchange initiating station that initiates the frame exchange may omit not only the NDPA frame transmission but also the NDP frame transmission and the feedback frame transmission.
- the frame exchange initiating station may measure the channel state while receiving a PPDU including a response to a control frame, for example, an RTS frame, an MU-RTS frame, an MU-RTS frame, and a trigger frame of a different type.
- the frame exchange initiating station may acquire a steering matrix to be used for MIMO transmission based on the measured channel state.
- the frame exchange initiating station may acquire a steering matrix based on the measured channel state.
- the frame exchange initiating station may perform MIMO transmission using the obtained steering matrix.
- the frame exchange initiating station may insert padding into the control frame based on the RF chain change required time as described above. Specifically, the frame exchange initiation station may insert padding into the control frame based on a value obtained by subtracting the SIFS from the RF chain change required time.
- the frame exchange initiating station may transmit a QoS data frame instead of a control frame.
- a single radio multi-link device may transmit an Ack frame or a Block Ack frame in response to the QoS data frame.
- the frame exchange initiating station may set the TRQ (training request) bit of the control frame and the QoS data frame to 1.
- a receiver of the control frame may be set as one station.
- the frame exchange initiating station sets the TRQ field to 1 and transmits the MU-RTS frame.
- the frame exchange initiating station transmits the PPDU including the MU-RTS frame, and the frame exchange initiating station receives the PPDU including the CTS frame as a response to the MU-RTS frame and measures the channel state.
- the frame exchange initiating station acquires a steering matrix based on the acquired channel state, and performs MIMO transmission using the acquired steering matrix.
- the frame exchange initiating station transmits the RTS frame instead of the MU-RTS frame. This may be the case in which the RF chain required time is shorter than the SIFS.
- the frame exchange initiating station and the station of the single radio multi-link device operate in the same manner as in the embodiment of FIG. 41( a ).
- the station of the single radio multi-link device transmits the BA frame as a single input single output (SISO).
- the last frame exchange may be performed with single input single output (SISO) (1x1).
- SISO single input single output
- the station of a single radio multi-link device may transmit the last frame of the frame exchange sequence performed immediately after changing the RF chain to the SISO (1x1).
- the station of a single radio multi-link device may change the RF chain.
- the station of a single radio multi-link device may start changing the RF chain before transmitting the last frame of the frame exchange sequence performed immediately after changing the RF chain.
- the NDP sounding protocol initiating station may determine the MIMO transmission start time based on the time required for changing the RF chain of a single radio multi-link device. Specifically, the NDP sounding protocol initiation station may delay the MIMO transmission start time to the time when the RF chain change of a single radio multi-link device is completed. For example, if the RF chain change is not completed while exchanging a response frame for a control frame/control frame, for example, an RTS frame/CTS frame or an MU-RTS frame/CTS frame, the NDP sounding protocol initiating station transmits MIMO The start time can be delayed. Specifically, the NDP sounding protocol initiating station may transmit the first PPDU transmitted after the control frame/control frame response by using the SISO.
- the MIMO transmission of the NDP sounding protocol initiating station may not be allowed.
- the explicit and implicit NDP sounding protocols described above may not be allowed before the RF chain change is complete.
- the NDP sounding protocol initiating station determines whether the RF chain change is completed during the exchange of the control frame/response frame for the control frame based on the required time for the RF chain change indicated by the Capability element transmitted by a single radio multi-link device. can do.
- a station that has performed a frame exchange sequence in a link in which the use of multiple RF chains is supported may transmit the remaining frames in the corresponding frame exchange sequence using SISO.
- a station that has performed a frame exchange sequence in a link in which the use of a plurality of RF chains is supported is referred to as a frame exchange sequence performing station. That is, when a single radio multi-link device performs transmission using SISO, the station performing the frame exchange sequence may not be allowed to transmit the remaining frames in the corresponding frame exchange sequence using MIMO.
- the frame exchange sequence performing station may transmit the remaining frames in the corresponding frame exchange sequence using SISO.
- the ACK may include an ACK frame and a BA frame. Therefore, when a single radio multi-link device transmits an ACK for transmission of a frame exchange sequence performing station using SISO, the frame exchange sequence performing station cannot transmit the remaining frames in the corresponding frame exchange sequence using MIMO.
- the RF chain change of a single radio multi-link device is not completed even during RTS frame and CTS frame exchange. Accordingly, in the embodiment of FIG. 42( a ), SISO is used even for PPDU and BA frame transmission after the RTS frame and the CTS frame are exchanged.
- the NDP sounding protocol initiating station receives the ACK frame, it determines that the change of the RF chain is complete. At this time, the NDP sounding protocol initiation station initiates the sounding protocol using MIMO (2x2).
- SISO is used even for PPDU transmission after the RTS frame and the CTS frame are exchanged. Since the RF chain change is completed after receiving the PPDU, the first station STA1 of the single radio multi-link device transmits the BA frame using MIMO (2x2). Since the first station STA1 of a single radio multi-link device transmits a BA frame using MIMO (2x2), the NDP sounding protocol initiating station determines that MIMO (2x2) transmission is allowed. Therefore, after the NDP sounding protocol initiating station receives the BA frame transmitted using MIMO (2x2), the NDP sounding protocol initiating station transmits a PPDU by using MIMO (2x2).
- a station supporting EDCA is referred to as a QoS station
- an AP supporting EDCA is referred to as a QoS AP
- a BSS supporting EDCA is referred to as a QoS BSS.
- QoS AP is referred to as AP
- QoS station is referred to as a station
- QoS BSS is referred to as BSS.
- EDCA traffic is classified into four AC (access categories) according to characteristics.
- the four ACs are AC_VO (AC Voice), AC_VI (AC Video), AC_BE (AC Best effort), and AC_BK (AC Background).
- a value of a parameter related to CW is determined according to AC.
- the maximum value of TXOP may be determined according to AC.
- the value of the AIFSN parameter may be determined according to the AC.
- Traffic may be mapped to four ACs for each traffic category (TC) or traffic stream (TS). Traffic mapped to four ACs is managed in four queues operated for each AC.
- AC_VO is an AC for traffic that does not have a large absolute amount of traffic like voice traffic, but is vulnerable to transmission delay, and relatively small CW parameter and AIFSN parameter values are mapped.
- the maximum value of TXOP of AC_VO has a relatively smaller value than the maximum value of TXOP of other ACs.
- AC_VI is more robust to transmission delay than voice traffic, but it is AC for video traffic that requires low-latency transmission and has to handle a large amount of traffic.
- AC_VI is larger than AC_VO, but the CW parameter and AIFSN parameter value smaller than the CW parameter and AIFSN parameter of other AC are mapped.
- the maximum value of TXOP of AC_VO is about twice as long as the maximum value of TXOP of AC_VI.
- AC_BE is AC for traffic resistant to transmission delay, and most general traffic except for voice data and streaming video data can be classified as AC_BE. Values larger than the CW and AIFSN parameters of AC_VO and the CW and AIFSN parameters of AC_VI are mapped to the CW and AIFSN parameters of AC_BE. In addition, a separate TXOP maximum value is not mapped to AC_BE. In AC_BE, transmission using a continuous transmission sequence is not allowed.
- AC_BK is traffic robust to transmission delay similar to AC_BE, but is an AC for traffic with a lower priority than BE traffic. The same CW parameter value as AC_BE is mapped to AC_BK, and a larger value than the AIFSN parameter of AC_BE is mapped to the AIFSN parameter value. In addition, a separate TXOP maximum value is not mapped to AC_BK. In AC_BK, transmission using a continuous transmission sequence is not allowed.
- the four ACs described above are mapped to UP (user-priority) of 802.1D, and the EDCA AC is determined according to the UP value of the traffic received over the wire or the TID of the MSDU indicated by the upper layer.
- the TID of the MSDU indicates a value of 0 to 7
- the value indicated by the TID may correspond to UP in a one-to-one manner.
- the default CW parameters (CWmin, CWmax), AIFSN parameter, and TXOP maximum value of each of the four ACs are defined in the 802.11 standard.
- the CW parameters (CWmin, CWmax), AIFSN parameter, and TXOP maximum value of AC may be changed by the AP, and different values may be used for each BSS.
- traffic is stored in a queue corresponding to the AC of the traffic among the four queues.
- Channel access contention is performed between the four ACs, and the traffic of the AC winning the contention is transmitted.
- access parameters for each AC (CW[AC], AIFSN[AC]) are used. In this case, the channel access operation is the same as the channel access operation of the DCF.
- the transmission priority may be applied to each AC.
- HCCA HCF controlled channel access
- 802.11 MAC protocol may be applied to HCCA (HCF controlled channel access) for QoS management.
- HCA provides a centralized/hybrid coordinator function to ensure TS (Traffic Stream) QoS of applications that need to be serviced periodically (such as Voice and Video).
- TS Traffic Stream
- SPCA Service Period Channel Access
- a dynamic allocation of service period function, etc. may be used. However, this can only be used by DMG stations.
- a QoS enhancement method for multi-link devices may be required.
- An independent transmission queue may be used for each link of the multi-link device. In this case, the queue may be logically independent.
- QoS of the traffic can be strengthened. This will be described with reference to FIG. 44 .
- the multi-link device transmits traffic mapped to each station of the multi-link device according to an embodiment of the present invention.
- the AP multi-link device includes a first AP (AP1) to a fourth AP (AP4).
- the non-AP multi-link device (Non-AP MLD) includes a first station (non-AP STA1) to a fourth station (non-AP STA4).
- Each of the first station (non-AP STA1) to the fourth station (non-AP STA4) operates in the first link (Link1) to the fourth link (Link1).
- Each of the first APs (AP1) to the fourth APs (AP4) operates in the first link (Link1) to the fourth link (Link1).
- traffic is mapped for each AC to each of the first APs (AP1) to the fourth APs (AP4).
- AC_BK is mapped to a first AP (AP1)
- AC_BE is mapped to a second AP (AP2)
- AC_VI is mapped to a third AP (AP3)
- AC_VO is mapped to a fourth AP (AP4).
- traffic corresponding to AC_BK is transmitted through the first AP (AP1)
- traffic corresponding to AC_BE is transmitted through the second AP (AP2)
- traffic corresponding to AC_VI is transmitted through the third AP (AP3)
- traffic corresponding to AC_VO is transmitted through the fourth AP (AP4).
- Each link may have different channel quality and load conditions. Also, the performance and operating bandwidth of each station may be different. Accordingly, the bandwidth and MCS of a PPDU including traffic may vary depending on which link the multi-link device maps traffic to.
- the first AP (AP1) of the AP multi-link device (AP MLD) when the first AP (AP1) operates in the 2.4 GHz band, the first AP (AP1) may operate a 40 MHz operating channel.
- the fourth AP (AP4) when the fourth AP (AP4) operates in the 6 GHz band, the fourth AP (AP4) may operate an operating channel of up to 320 MHz.
- the AP multi-link device (AP MLD) may be mapped to the traffic that requires high throughput and low-latency transmission to the fourth AP (AP4).
- the multi-link device may map traffic to each of a plurality of links in consideration of traffic characteristics. Through this, the QoS of traffic transmission can be strengthened.
- the TID is mapped to each link, and transmission of traffic corresponding to the TID mapped to the link in each link may be prioritized. This will be described with reference to FIG. 45 .
- Traffic transmitted in a WLAN is identified by a TID.
- a MAC frame for example, a data frame or a QoS data frame, signals a TID of traffic included in the MAC frame through a TID service field.
- the QoS control field may include a TID service field.
- the TID identifies the traffic included in the MSDU or fragment of the MAC frame or the A-MSDU.
- the TID corresponds to a user priorities (UP) or a traffic stream identifier (TSID).
- the TID service field is a 4-bit field in total and may indicate values from 0 to 15.
- the value of the TID subfield indicates the UP of the MSDU included in the frame body of the MAC frame including the TID subfield.
- the MAC frame is processed in the MAC entity using AC parameters corresponding to UP according to EDCA.
- the value of the TID subfield indicates the TSID of the MSDU included in the frame body of the MAC frame including the TID subfield.
- the MAC frame is processed by the MAC entity using the parameter corresponding to the UP of the TSID indicated in the User Priority service field of the TS Info field of TSPEC.
- the UP of the TSID may be indicated through the User Priority field of the TCLAS.
- the Access Policy of the TSID is indicated by the Access Policy field of the TS Info subfield.
- the 7th and 8th bits of the Access Policy subfield are 10b , it indicates EDCA, and when 11b , it indicates HCCA.
- the multi-link device maps the TID of the TS to the link, from the Intra-Access Priority field of the Intra-Access Category Priority element of the ADDTS Request frame used when generating the TS, the alternate queue to be used for UP and TS transmission of the TS (Alternate) queue) can be obtained.
- the multi-link device may use information about the UP and the replacement queue obtained when transmitting traffic corresponding to the TID of the TS.
- a TID may be mapped to each of a plurality of links in which the multi-link device operates.
- the multi-link device may signal information about a TID mapped to each link to a multi-link device associated with the multi-link device.
- the multi-link device receiving the signaling may accept or reject the TID and link mapping.
- frame exchange may be performed on each link without TID restriction.
- frame exchange may be performed in each link according to a default mapping between the TID and the link.
- the multi-link device may have to map all TIDs to one or more links.
- the multi-link device transmits a frame including traffic corresponding to a TID mapped to a corresponding link in a link, and transmission of a frame including traffic corresponding to a TID that is not mapped to the link may not be allowed. have.
- the mapping between the TID and the link may be performed for each multi-link device. Also, the mapping between the TID and the link may be mapped for each transmission direction. For example, in one link, the TID mapped to the uplink and the TID mapped to the downlink may be different.
- the first multi-link device maps TID values 0 to 3 to the first link
- the second multi-link device connects the first TID values 4 to 7 may be mapped to links.
- mapping between TID and link may be replaced with mapping between AC and link or between UP and link or between TC and link or between TS and link.
- the remaining TID values not explicitly indicated in the mapping between the TID and the link may be mapped to the remaining link.
- the remaining TID values excluding TID values 0 to 3 may be mapped to the second link.
- transmission of traffic corresponding to all TIDs in the second link may be allowed.
- the mapping between the TID and the link may be changed during operation as well as the initial connection between the multi-link devices.
- the multi-link device may change the mapping between the TID and the link.
- the multi-link device may disconnect the station when the station of a specific link enters the power saving mode.
- the multi-link device may request the counterpart multi-link device to change the mapping between the TID and the link.
- the non-AP multi-link device may request the AP multi-link device to map TID values 0 to 3 to the second link.
- the multi-link device may request the counterpart multi-link device to change the mapping between the TID and the link.
- the multi-link device when the multi-link device rejects the TID-link mapping request, the multi-link device that transmitted the TID-link mapping request requests again the same TID-link mapping as the previously requested TID-link mapping. It may be restricted for a pre-specified period of time. This is to prevent repeated requests for mapping between TIDs and links.
- the predetermined time may be a time indicated by the AP.
- the AP multi-link device may signal a predetermined time through the BSS operation parameter.
- the multi-link device may signal the mapping between the TID and the link using a TID-to-Link Mapping element.
- the TID-to-Link Mapping element may include a Link ID field.
- the Link ID field indicates a link signaling a TID-to-Link Mapping element.
- the TIDs Info field indicates information on the TID mapped to the link indicated by the Link ID field.
- the TIDs Info field may include a field indicating the value of the TID mapped to the link indicated by the Link ID field.
- the TIDs Info field may include a bitmap indicating the value of the TID mapped to the link indicated by the Link ID field. In this case, each bit of the bitmap is mapped to a specific TID, and when the bit is set to 1, it may indicate that the TID corresponding to the bit is mapped to the link indicated by the Link ID field.
- the AP multi-link device plans to transmit traffic having TIDs 0 to 3 among traffic to be transmitted to the non-AP multi-link device (non-AP MLD) on the first link (Link1). .
- the AP multi-link device maps TID values 0 to 3 to the first link Link1 using the TID-to-Link Mapping element to the non-AP multi-link device (non-AP MLD), and the second It signals that the TID values 4 to 7 are mapped to the link Link2.
- the TID-to-Link Mapping element includes two Link ID fields indicating a first link and a second link, respectively, and two links indicating information about a TID mapped to the first link and information mapped to a second link, respectively. It contains two TIDs Info fields.
- the TIDs Info field may include 7 bits indicating TIDs 0 to 7, respectively.
- 8 bits of the TIDs info subfield may be set to 11110000 b to indicate TIDs 0 to 3
- 8 bits of the TIDs info subfield may be set to 00001111 b to indicate TIDs 4 to 7.
- the TIDs Info field may include a Min TID field and a Max TID field.
- the Min TID field indicates a minimum value among TIDs mapped to a link corresponding to the TIDs Info field
- the Max TID field indicates a maximum value among TIDs mapped to a link corresponding to the TIDs Info field.
- Each of the Min TID field and the Max TID field may be a 3-bit or 4-bit field. For example, when the Min TID field and the Max TID field each have 3 bits, when the TIDs Info field indicates 0 to 3, the Min TID field may be set to 000 and the Max TID field may be set to 011 b .
- the TID-to-Link Mapping element may signal only the TID mapped to the first link, and the TID mapped to the second link may be implicitly signaled. Specifically, since the TID-to-Link Mapping element explicitly signals that TIDs of 0 to 7 are mapped to the first link, the TID-to-Link Mapping element implicitly signals that the remaining TIDs are mapped to the second link.
- the non-AP multi-link device accepts the mapping between the TID and the link indicated by the TID-to-Link Mapping element.
- the multi-link device may transmit traffic by differentiating ACs according to EDCA. For example, when the TID corresponding to AC_VO and the TID corresponding to AC_BK are mapped to the first link, the multi-link device may transmit the traffic corresponding to AC_VO in preference to the traffic corresponding to AC_BK according to EDCA. In addition, all TIDs must be mapped to at least one link, and the multi-link device may not allow any one TID to request a mapping between a TID and a link that is not mapped to any link.
- a multi-link device to which the EML mode is applied may not be allowed to perform mapping between a TID and a link.
- a basic mapping between a TID and a link may be applied to a multi-link device to which the EML mode is applied. In this case, the multi-link device to which the EML mode is applied cannot negotiate for mapping between the TID and the link.
- the counterpart multi-link device may reject the TID-link mapping request.
- the counterpart multi-link device may not transmit a response to the TID-link mapping request.
- the multi-link device to which the EML mode is applied may not perform mapping between the TID and the link only for the EML link. Therefore, even in a multi-link device to which the EML mode is applied, the mapping between the TID and the link can be performed on a link to which the EML mode is not applied.
- the basic mapping between TID and link in the EML link among the links in which the multi-link device operates is performed. can be applied. In this case, the basic mapping between the TID and the link may be performed without a separate negotiation.
- the multi-link device connected to the multi-link device for which the EML mode is activated may also apply the basic mapping between the TID and the link to the EML link.
- the multi-link device may perform association again to activate the EML mode.
- the multi-link device may initialize information for link operation.
- the multi-link device may initialize the mapping between the link and the TID.
- the AP multi-link device includes the first AP (AP1) and the second AP (AP2), and the non-AP multi-link device (STA MLD) is the first station (STA1). ) and a second station STA2.
- the first AP (AP1) and the first station (STA1) operate on a first link (Link1)
- the second AP (AP2) and the second station (STA2) operate on a second link (Link2).
- the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) map TID values 0 to 3 to the first link Link1, and map TID values 4 to 7 to the second link Link2. do.
- the EMLSR mode is activated in the non-AP multi-link device (STA MLD), and the EMLSR mode is applied to both the first link Link1 and the second link Link2.
- the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) apply the basic mapping between the TID and the link. That is, the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) map TID values 0 to 7 to the first link Link1, and TID values 0 to 7 to the second link Link2. map up to
- the non-AP multi-link device (STA MLD) may transmit a (Re)Association Request frame to activate the EMLSR mode.
- the (Re)Association Request frame may include a Multi-Link element.
- the Multi-Link element will be described with reference to FIG. 48 .
- the (Re)Association Request frame transmitted by the non-AP multi-link device to activate the EMLSR mode may include a Multi-Link element.
- the non-AP multi-link device may set the EMLSR mode subfield of the Common Info field of the Multi-Link element to 1.
- the Common Info field of the Multi-Link element may be in a Basic variant format.
- the AP Multi-Link device may recognize that the Non-AP Multi-Link device intends to activate the EMLSR mode.
- the AP multi-link device and the Non-AP multi-link device may activate the EMLSR mode.
- the mapping between the TID and the link used before the EML mode is activated may be applied again.
- the multi-link device may not perform mapping negotiation between the TID and the link again.
- the AP multi-link device includes the first AP (AP1) and the second AP (AP2)
- the non-AP multi-link device is the first station (STA1). ) and a second station STA2.
- the EMLSR mode is activated in the non-AP multi-link device (STA MLD), and the EMLSR mode is applied to both the first link Link1 and the second link Link2.
- the first AP (AP1) and the first station (STA1) operate on a first link (Link1)
- the second AP (AP2) and the second station (STA2) operate on a second link (Link2).
- An AP multi-link device (AP MLD) and a non-AP multi-link device (STA MLD) apply a basic mapping between a TID and a link. That is, the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) map TID values 0 to 7 to the first link Link1, and TID values 0 to 7 to the second link Link2. map up to The EMLSR mode is deactivated in the non-AP multi-link device (STA MLD).
- the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) apply the mapping between the TID and the link applied before the EMLSR mode is activated to the first link (Link1) and the second link (Link2). do. That is, the AP multi-link device (AP MLD) and the non-AP multi-link device (STA MLD) map TID values 0 to 3 to the first link Link1, and TID values 4 to 7 to the second link Link2. map up to
- the AP multi-link device may transmit an initial control frame to perform transmission to the multi-link device in which the EML mode is activated.
- the initial control frame may be an MU-RTS frame or a trigger frame of another variant.
- the trigger frame of another variant may be an ML-RTS frame, which is an RTS frame for multi-link.
- the non-AP multi-link device that has received the trigger frame of another variant may transmit a response frame to the trigger frame of the other variant.
- the initial control frame may be a buffer status report poll (BSRP) trigger frame.
- the non-AP multi-link device receiving the BSRP trigger frame may transmit the BSR frame as a response frame.
- BSRP buffer status report poll
- the non-AP multi-link device may set the length of the initial control frame based on the type of the initial control frame.
- the padding may be to secure time for resetting the RF chain as described above.
- the MU-RTS frame may include padding corresponding to a time equal to or longer than a time of (RF switching latency - SIFS - CTStime - SIFS).
- the BSRP trigger frame may include padding corresponding to a time equal to or longer than a time of (RF switching latency - SIFS - BSRtime - SIFS).
- the BSRtime may be a transmission required time of the BSR frame, for example, airtime.
- the BSRtime may be a value determined assuming that the BSR frame is transmitted at a specific data rate.
- the non-AP multi-link device may determine the length of the padding of the trigger frame based on the value of the UL Length subfield of the Common Info field of the trigger frame. This is because the station receiving the trigger frame determines the length of the PPDU including the response frame to the trigger frame based on the value of the UL Length subfield of the Common Info field.
- the non-AP multi-link device (RF switching latency - SIFS - UL length (length of the response frame) - SIFS indicated through the trigger frame) includes padding corresponding to the same or longer time in trigger inclusion.
- the non-AP multi-link device may determine the length of the padding of the BSRP trigger frame based on the value of the UL Length subfield of the Common Info field of the BSRP trigger frame.
- the multi-link device to which the EML mode is applied may signal the time required to change the RF chain.
- the AP multi-link device may determine the length of the padding of the initial control frame based on the signaled time required for changing the RF chain.
- the AP multi-link device may include padding corresponding to a time equal to or longer than the signaled RF chain change required time in the initial control frame.
- the multi-link device to which the EML mode is applied may signal the padding length of the initial control frame. This will be described with reference to FIG. 50 .
- 50 shows a Multi-Link element signaling information about a length of padding of an initial control frame according to an embodiment of the present invention.
- the AP multi-link device may determine the length of the padding of the initial control frame according to the signaled length of the padding. Specifically, the AP multi-link device may include padding having a length equal to or longer than that of the signaled padding in the initial control frame. In this case, a padding length may be signaled for each type of trigger frame. In a specific embodiment, the length of the signaled padding may be the length of the padding to be included in the MU-RTS frame.
- the AP multi-link device may include padding of a length other than the signaled length of the padding in the initial control frame.
- the AP multi-link device may determine the length of the padding of the initial control frame based on the difference between the airtime of the CTS frame and the airtime of the response frame to the initial control frame and the length of the signaled padding. have.
- the AP multi-link device adds a padding length equal to or longer than the value obtained by adding a padding length corresponding to the signaled padding length (CTStime- the time required for transmission of a response frame to the initial control frame (airtime)) to the initial control frame. can be inserted.
- CTStime the time required for transmission of a response frame to the initial control frame (airtime)
- the AP multi-link device may inversely calculate the required time for changing the RF chain based on the length of the signaled padding.
- the AP multi-link device may determine the length of the padding to be included in the initial control frame according to the time required for the inversely calculated RF chain change. This is because the length of the signaled padding is a value determined based on the required time of RF chain change.
- the length of the padding described above may be signaled through the Multi-Link element.
- the Multi-Link element includes an EMLSR Delay field indicating the length of the padding of the initial control frame.
- transmission, reception, or monitoring capability may be lost in some of the EML links due to link switching performed in the EML mode.
- monitoring may include at least one of CCA and preamble detection (PD).
- the multi-link device may not be able to transmit, receive, or monitor on the link for a predetermined time from the link switching time.
- the predetermined time may be determined based on the time required for link switching of the multi-link device in which the EML mode is activated.
- the predetermined time is a time interval in which the RF chain of the multi-link device in which the EML mode is activated is changed.
- a multi-link device supporting the EML mode and a station exchanging frames in the EML link may manage the TXOP in consideration of the frame exchange of the multi-link device in the EML mode.
- a multi-link device capable of managing the TXOP in the EML link in consideration of the frame exchange of the multi-link device in the EML mode which will be described with reference to FIG.
- the multi-link device terminates TXOP in a link in which frame exchange is performed in EMLSR mode in consideration of a DTIM beacon received in an EMLSR link in which frame exchange is not performed in EMLSR mode.
- transmission, reception, or monitoring capabilities may be lost in some of the EML links due to link switching performed in the EML mode.
- the multi-link device cannot transmit, receive, and monitor the other links among the EMLSR links.
- the monitoring may include at least one of CCA and preamble detection (PD).
- the multi-link device performs link switching to recover transmission, reception, or monitoring capability in the link, it is designated in advance from the link switching start time. During the time, the multi-link device may not be able to transmit, receive and monitor in the corresponding link.
- the predetermined time may be a delay time for link switching.
- the predetermined time is the multi-link supporting the EML mode.
- the RF chain of the device may include a changed time interval
- a multi-link device supporting the EML mode and a station exchanging frames in the EML link may manage the TXOP in consideration of the frame exchange of the multi-link device in the EML mode.
- a multi-link device supporting the EML mode may manage the TXOP in the EML link in consideration of frame exchange of the multi-link device in the EML mode.
- a multi-link device in which the EML mode is activated loses transmission, reception, or monitoring capability during the EML link in the EML mode.
- a station exchanging a frame with a multi-link device or a multi-link device in EML mode is one of the EML links based on the reception time of a specific frame in the first link, and the corresponding frame is exchanged in the second link in which the frame is exchanged TXOP for can be terminated.
- a multi-link device in which the EML mode is activated is referred to as a multi-link device
- a station exchanging frames with the multi-link device in which the EML mode is activated is referred to as a station.
- the station is the TXOP responder. Also, if the multi-link device is the responder of the TXOP, the station is the TXOP holder.
- the TXOP of the second link may have to be terminated before a time earlier by a predetermined time from the point at which the multi-link device intends to receive a specific frame in the first link.
- the predetermined time may be determined based on the link switching delay of the multi-link device. Specifically, the predetermined time may be determined based on the time required to change the RF chain of the multi-link device.
- the predetermined time may be a time required to change the RF chain of the multi-link device.
- the specific frame may be a frame received periodically.
- the specific frame may be a beacon frame.
- the specific frame may be a DTIM beacon frame.
- the time to receive a specific frame may be TBTT.
- the multi-link device or station may terminate the TXOP for the frame exchange in the second link in which the frame exchange was being performed in the EML mode based on the reception time of the specific frame in the first link.
- the station may terminate the TXOP on the second link based on information indicating that the multi-link device is going to receive a specific frame on the first link.
- information indicating that the multi-link device is going to receive a specific frame on the first link may be signaled by a method agreed between the multi-link device and the station.
- the information indicating that the multi-link device is going to receive a specific frame in the first link may be information signaling that the beacon frame of the first link is a DTIM beacon frame.
- the station If the station is a TXOP holder and the beacon to be received on the first link is a DTIM beacon, the station terminates the TXOP on the second link based on information indicating that the multi-link device is going to receive a specific frame on the first link.
- the multi-link device may not transmit a response frame to the initial control frame. Specifically, even if the multi-link device to which the EML mode is applied receives the initial control frame from the first link among the EML links, the multi-link device transmits a response frame to the initial control frame in order to receive a specific frame from the second link among the EML links. may not For example, even if the multi-link device to which the EML mode is applied receives the initial control frame from the first link among the EML links, the initial control frame is transmitted before the time specified by a predetermined time from the point of time when it intends to receive a specific frame from the second link among the EML links.
- the multi-link device may not transmit a response frame to the initial control frame in the first link.
- the initial control frame may be an MU-RTS frame, an ML-RTS frame, and a BSRP trigger frame as described above.
- the multi-link device may not transmit the CTS frame in response to the initial control frame. Through this, the multi-link device may reject the frame exchange initiation. This is an exception to the case in which the station must transmit the CTS frame when the station receives the MU-RTS frame or the RTS frame in the existing WLAN operation. Specifically, even if the multi-link device to which the EML mode is applied receives the initial control frame from the first link, which is one of the EML links, the multi-link device does not transmit a response frame to the initial control frame for frame exchange to be performed on the second link. it may not be
- the non-AP multi-link device for which EMLSR is activated includes a first station STA1 and a second station STA2.
- the first station STA1 operates on the first link Link 1
- the second station STA2 operates on the second link Link 2 .
- the first link Link1 receives an RTS frame from the first AP, and transmits a CTS frame in response to the RTS frame.
- the first station STA1 receives the PPDU from the first AP in the first link Link 1 .
- the first AP terminates the TXOP at a time earlier by the time required for the RF change of the non-AP multi-link device from the scheduled beacon frame reception time in the second link (Link 2).
- terminating the TXOP at a time prior to the time required for the RF change of the non-AP multi-link device from the scheduled beacon frame reception time in the second link Link 2 means that the first station STA1 performs the TXOP. The same can be applied even when acquired.
- the EMLSR multi-link device may not change the RF chain. This is because the beacon frame is not transmitted in MIMO.
- the multi-link device for which the EMLSR mode is activated may perform at least one of monitoring and channel access on the second link. In this case, even when the far link device completes the channel access procedure in the second link, it may not be allowed to perform transmission.
- the multi-link device may perform at least one of transmission and reception only at a predetermined data rate in the second link. At this time, the predetermined data rate may be any one of 6Mbps, 12Mbps, and 24Mbps.
- the station that wants to exchange frames with the multi-link device for which the EMLSR mode is activated starts the frame exchange procedure on the second link, which is one of the EMLSR links. may not be permitted to do so.
- the station that wants to exchange frames with the multi-link device with the EMLSR mode activated transmits the initial control frame on the second link, which is one of the EMLSR links. may not be allowed.
- the specific frame may be a group cast frame or a group addressed frame, for example, a beacon frame.
- the beacon frame may be a DTIM beacon frame.
- the present invention has been described using wireless LAN communication as an example, but the present invention is not limited thereto and may be equally applied to other communication systems such as cellular communication. Further, although the method, apparatus and system of the present invention have been described with reference to specific embodiments, some or all of the components, operations of the present invention may be implemented using a computer system having a general-purpose hardware architecture.
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Abstract
Description
Claims (20)
- 복수의 링크에서 각각 동작하는 복수의 스테이션을 포함하나, EMLSR(enhanced multi-link single radio) 모드에서 EMLSR 모드가 적용되는 복수의 링크인 EMLSR 링크의 제1 링크에서 프레임 교환을 수행하는 동안 상기 EMLSR 링크의 제2 링크에서 전송 및 수신을 수행하지 않는 멀티 링크 장치에서,송수신부; 및프로세서를 포함하고,상기 프로세서는상기 EMLSR 모드에서 상기 제1 링크에서 상기 멀티 링크 장치가 포함하는 복수의 스테이션 중 하나인 제1 스테이션이 TXOP(transmission opportunity) 홀더로서 상기 프레임 교환을 수행할 때, 상기 제2 링크에서 상기 멀티 링크 장치가 비콘 프레임을 수신하기로 한 시점보다 미리 지정된 시간만큼 이른 시점 이전에 상기 프레임 교환을 위한 TXOP을 종료하고,상기 미리 지정된 시간은 상기 멀티 링크 장치가 링크 스위칭을 수행하기 위한 지연 시간인멀티 링크 장치.
- 제1항에서,상기 프로세서는상기 EMLSR 모드에서 상기 제1 링크에서 상기 프레임 교환을 개시하는 초기 제어 프레임을 수신하고,상기 제2 링크에서 상기 비콘 프레임을 수신하기 위해 상기 초기 제어 프레임에 대한 응답 프레임을 전송하지 않는멀티 링크 장치.
- 제2항에서,상기 초기 제어 프레임이 개시하는 프레임 교환이 상기 제2 링크에서 상기 멀티 링크 장치가 상기 비콘 프레임을 수신하는 시점으로부터 상기 미리 지정된 시간만큼 이른 시간 전에 완료되지 않는 경우, 상기 프로세서는 상기 초기 제어 프레임에 대한 응답을 전송하지 않고,상기 초기 제어 프레임이 개시하는 프레임 교환이 상기 제2 링크에서 상기 멀티 링크 장치가 상기 비콘 프레임을 수신하는 시점으로부터 상기 미리 지정된 시간만큼 이른 시간 전에 완료되는 경우, 상기 프로세서는 상기 초기 제어 프레임에 대한 응답을 전송하는멀티 링크 장치.
- 제2항에서,상기 초기 제어 프레임은 MU-RTS(multi-user request to send) 프레임 또는 BSRP(buffer status report poll)인멀티 링크 장치.
- 제2항에서,상기 비콘 프레임은 DTIM 비콘인멀티 링크 장치.
- 제2항에서,상기 초기 제어 프레임은 미리 지정된 포맷을 이용하여 미리 지정된 데이터 레이트로 전송되는멀티 링크 장치.
- 제1항에서,상기 미리 지정된 시간은 상기 멀티 링크 장치에 의해 시그널링되는멀티 링크 장치.
- 제1항에서,상기 프로세서는상기 링크 스위칭을 위해 필요한 초기 제어 프레임의 패딩의 최소 길이(duration)를 시그널링하고, 상기 초기 제어 프레임은 상기 EMLSR 모드에서 상기 EMLSR 링크에서 프레임 교환을 개시하고,상기 초기 제어 프레임은 상기 패딩의 최소 길이와 같거나 긴 시간에 대응하는 패딩을 포함하는멀티 링크 장치.
- 제1항에서,상기 EMLSR 모드는 상기 멀티 링크 장치가 포함하는 복수의 스테이션이 동작하는 상기 복수의 링크 중 일부에만 적용되는멀티 링크 장치.
- 복수의 링크에서 각각 동작하는 복수의 스테이션을 포함하나, EMLSR(enhanced multi-link single radio) 모드에서 EMLSR 모드가 적용되는 복수의 링크인 EMLSR 링크의 제1 링크에서 프레임 교환을 수행하는 동안 상기 EMLSR 링크의 제2 링크에서 전송 및 수신을 수행하지 않는 멀티 링크 장치와 통신하는 액세스 포인트에서,송수신부; 및프로세서를 포함하고,상기 프로세서는상기 EMLSR 모드에서 상기 제1 링크에서 상기 프레임 교환을 개시하는 초기 제어 프레임을 전송하고, 상기 멀티 링크 장치가 상기 제2 링크에서 비콘 프레임을 수신하기로 한 시점보다 미리 지정된 시간만큼 이른 시점 이전에 상기 프레임 교환을 위한 TXOP을 종료하고상기 미리 지정된 시간은 상기 멀티 링크 장치가 링크 스위칭을 수행하기 위한 지연 시간인멀티 링크 장치.
- 제10항에서,상기 초기 제어 프레임은 MU-RTS(multi-user request to send) 프레임 또는 BSRP(buffer status report poll)인멀티 링크 장치.
- 제10항에서,상기 비콘 프레임은 DTIM 비콘인멀티 링크 장치.
- 제10항에서,상기 프로세서는상기 초기 제어 프레임을 미리 지정된 포맷을 이용하여 미리 지정된 데이터 레이트로 전송하는멀티 링크 장치.
- 제10항에서,상기 미리 지정된 시간은 상기 멀티 링크 장치에 의해 시그널링되는멀티 링크 장치.
- 제14항에서,상기 프로세서는상기 멀티 링크 장치로부터 상기 링크 스위칭을 위해 필요한 초기 제어 프레임의 패딩의 최소 길이(duration)를 수신하고,상기 초기 제어 프레임에 상기 패딩의 최소 길이와 같거나 긴 시간에 대응하는 패딩을 포함시키는멀티 링크 장치.
- 제10항에서,상기 EMLSR 모드는 상기 멀티 링크 장치가 포함하는 복수의 스테이션이 동작하는 상기 복수의 링크 중 일부에만 적용되는멀티 링크 장치.
- 복수의 링크에서 각각 동작하는 복수의 스테이션을 포함하나, EMLSR(enhanced multi-link single radio) 모드에서 EMLSR 모드가 적용되는 복수의 링크인 EMLSR 링크의 제1 링크에서 프레임 교환을 수행하는 동안 상기 EMLSR 링크의 제2 링크에서 전송 및 수신을 수행하지 않는 멀티 링크 장치의 동작 방법에서,상기 EMLSR 모드에서 상기 제1 링크에서 상기 멀티 링크 장치가 포함하는 복수의 스테이션 중 하나인 제1 스테이션이 TXOP(transmission opportunity) 홀더로서 상기 프레임 교환을 수행할 때, 상기 제2 링크에서 상기 멀티 링크 장치가 비콘 프레임을 수신하기로 한 시점보다 미리 지정된 시간만큼 이른 시점 이전에 상기 프레임 교환을 위한 TXOP을 종료하는 단계를 포함하고,상기 미리 지정된 시간은 상기 멀티 링크 장치가 링크 스위칭을 수행하기 위한 지연 시간인동작 방법.
- 제17항에서,상기 동작 방법은상기 EMLSR 모드에서 상기 제1 링크에서 상기 프레임 교환을 개시하는 초기 제어 프레임을 수신하는 단계; 및상기 제2 링크에서 상기 비콘 프레임을 수신하기 위해 상기 초기 제어 프레임에 대한 응답 프레임을 전송하지 않는 단계를 더 포함하는동작 방법.
- 제18항에서,상기 제2 링크에서 상기 비콘 프레임을 수신하기 위해 상기 초기 제어 프레임에 대한 응답 프레임을 전송하지 않는 단계는상기 초기 제어 프레임이 개시하는 상기 프레임 교환이 상기 제2 링크에서 상기 멀티 링크 장치가 상기 비콘 프레임을 수신하는 시점으로부터 상기 미리 지정된 시간만큼 이른 시간 전에 완료되지 않는 경우, 상기 초기 제어 프레임에 대한 응답을 전송하지 않는 단계와상기 초기 제어 프레임이 개시하는 상기 프레임 교환이 상기 제2 링크에서 상기 멀티 링크 장치가 상기 비콘 프레임을 수신하는 시점으로부터 상기 미리 지정된 시간만큼 이른 시간 전에 완료되는 경우, 상기 초기 제어 프레임에 대한 응답을 전송하는 단계를 포함하는동작 방법.
- 제18항에서,상기 초기 제어 프레임은 MU-RTS(multi-user request to send) 프레임 또는 BSRP(buffer status report poll)인동작 방법.
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GB2619563A (en) * | 2022-06-10 | 2023-12-13 | Canon Kk | EDCA backoff procedures and state switches for EMLSR or EMLMR co-affiliated stations |
GB2620223A (en) * | 2022-07-01 | 2024-01-03 | Canon Kk | Per-link (TWT. R-TWT) procedure support and state switches for EMLSR or ELMLR co-affiliated stations |
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WO2024035039A1 (ko) * | 2022-08-08 | 2024-02-15 | 한국전자통신연구원 | Emlsr을 지원하는 무선랜에서 링크의 변경 방법 및 장치 |
WO2024039144A1 (en) * | 2022-08-15 | 2024-02-22 | Samsung Electronics Co., Ltd. | Method and apparatus for choosing operating mode for multi-link device |
EP4380297A1 (en) * | 2022-12-02 | 2024-06-05 | MediaTek Inc. | Method for performing medium access control protocol data unit dispatch control in multi-link operation architecture, and associated apparatus |
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