CN117223387A - Wireless communication method using multilink and wireless communication terminal using the same - Google Patents
Wireless communication method using multilink and wireless communication terminal using the same Download PDFInfo
- Publication number
- CN117223387A CN117223387A CN202280031685.9A CN202280031685A CN117223387A CN 117223387 A CN117223387 A CN 117223387A CN 202280031685 A CN202280031685 A CN 202280031685A CN 117223387 A CN117223387 A CN 117223387A
- Authority
- CN
- China
- Prior art keywords
- mld
- link
- subfield
- neighbor
- information
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 116
- 238000004891 communication Methods 0.000 title claims abstract description 95
- 230000005540 biological transmission Effects 0.000 claims description 125
- 239000000523 sample Substances 0.000 claims description 101
- 230000004044 response Effects 0.000 claims description 98
- 230000001360 synchronised effect Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 description 37
- 101150081243 STA1 gene Proteins 0.000 description 21
- 230000011664 signaling Effects 0.000 description 15
- 238000013507 mapping Methods 0.000 description 13
- OVGWMUWIRHGGJP-WTODYLRWSA-N (z)-7-[(1r,3s,4s,5r)-3-[(e,3r)-3-hydroxyoct-1-enyl]-6-thiabicyclo[3.1.1]heptan-4-yl]hept-5-enoic acid Chemical compound OC(=O)CCC\C=C/C[C@H]1[C@H](/C=C/[C@H](O)CCCCC)C[C@H]2S[C@@H]1C2 OVGWMUWIRHGGJP-WTODYLRWSA-N 0.000 description 12
- 101100366889 Caenorhabditis elegans sta-2 gene Proteins 0.000 description 12
- 230000006870 function Effects 0.000 description 12
- 101100161473 Arabidopsis thaliana ABCB25 gene Proteins 0.000 description 9
- 101100096893 Mus musculus Sult2a1 gene Proteins 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 9
- 238000001514 detection method Methods 0.000 description 7
- 230000006835 compression Effects 0.000 description 6
- 238000007906 compression Methods 0.000 description 6
- OVGWMUWIRHGGJP-WVDJAODQSA-N (z)-7-[(1s,3r,4r,5s)-3-[(e,3r)-3-hydroxyoct-1-enyl]-6-thiabicyclo[3.1.1]heptan-4-yl]hept-5-enoic acid Chemical compound OC(=O)CCC\C=C/C[C@@H]1[C@@H](/C=C/[C@H](O)CCCCC)C[C@@H]2S[C@H]1C2 OVGWMUWIRHGGJP-WVDJAODQSA-N 0.000 description 5
- 101000988961 Escherichia coli Heat-stable enterotoxin A2 Proteins 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 4
- 238000012549 training Methods 0.000 description 4
- VYLDEYYOISNGST-UHFFFAOYSA-N bissulfosuccinimidyl suberate Chemical compound O=C1C(S(=O)(=O)O)CC(=O)N1OC(=O)CCCCCCC(=O)ON1C(=O)C(S(O)(=O)=O)CC1=O VYLDEYYOISNGST-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 101710082751 Carboxypeptidase S1 homolog A Proteins 0.000 description 2
- 102100023804 Coagulation factor VII Human genes 0.000 description 2
- 238000003722 High energy mechanical milling Methods 0.000 description 2
- 101100172132 Mus musculus Eif3a gene Proteins 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000008054 signal transmission Effects 0.000 description 2
- 238000010792 warming Methods 0.000 description 2
- 241000760358 Enodes Species 0.000 description 1
- 101100395869 Escherichia coli sta3 gene Proteins 0.000 description 1
- 101000752249 Homo sapiens Rho guanine nucleotide exchange factor 3 Proteins 0.000 description 1
- 102100021689 Rho guanine nucleotide exchange factor 3 Human genes 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011017 operating method Methods 0.000 description 1
- 230000001151 other effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
Abstract
A method and apparatus for transmitting and receiving frames performed by a first Multi-link Device (MLD) in a wireless communication system, wherein the first MLD includes a plurality of stations respectively operating on a plurality of links. Specifically, the first MLD according to the present invention may receive a beacon frame (beacon) through a first link of a first AP of a plurality of Access Points (APs) respectively operating on one or more links included in the second MLD, and may be associated with one or more APs of the plurality of APs based on the received beacon frame.
Description
Technical Field
The present invention relates to a wireless communication method using multiple links and a wireless communication terminal using the same.
Background
In recent years, as the supply of mobile devices expands, wireless LAN (Wireless LAN) technology capable of providing rapid wireless internet services to mobile devices has been paid attention to. Wireless LAN technology allows mobile devices, including smart phones, smart tablets, laptop computers, portable multimedia players, embedded devices, etc., to wirelessly access the internet in a home or company or special service providing area based on short-range wireless communication technology.
Since the initial wireless LAN technology is supported using a frequency of 2.4GHz, the institute of electrical and electronics engineers (Institute of Electrical and Electronics Engineers, IEEE) 802.11 has commercialized or developed various technical standards. First, IEEE 802.11b supports a maximum communication speed of 11Mbps when using frequencies of the 2.4GHz band. Compared to the frequency of the significantly congested 2.4GHz band, the IEEE 802.11a commercialized after the IEEE 802.11b uses frequencies other than the 2.4GHz band but the 5GHz band to reduce the influence of interference, and increases the communication speed to a maximum of 54Mbps by using the OFDM technology. However, the disadvantage of IEEE 802.11a is that the communication distance is shorter than IEEE 802.11b. Further, similar to IEEE 802.11b, IEEE 802.11g uses a frequency of 2.4GHz band to achieve a communication speed of a maximum of 54Mbps and satisfies backward compatibility to be significantly focused, and further, is superior to IEEE 802.11a in terms of communication distance.
Further, as a technical standard established to overcome a limitation of a communication speed pointed out as a vulnerability in a wireless LAN, IEEE 802.11n has been provided. IEEE 802.11n aims to increase the speed and reliability of the network and to extend the working distance of the wireless network. In more detail, IEEE 802.11n supports High Throughput (HT), in which a data processing speed is 540Mbps or more at maximum, and further, is based on a multiple input and multiple output (Multiple Inputs Multiple Outputs, MIMO) technology, in which a plurality of antennas are used at both sides of a transmission unit and a reception unit to minimize a transmission error and optimize a data speed. Furthermore, the standard can use a compilation scheme that transmits multiple copies that are superimposed on each other in order to increase data reliability.
As the supply of wireless LANs becomes active, and further, as applications using wireless LANs diversify, a demand for new wireless LAN systems supporting higher throughput (extremely high throughput (Very High Throughput, VHT)) than the data processing speed supported by IEEE 802.11n has been paid attention to. Among them, IEEE 802.11ac supports a bandwidth (80 to 160 MHz) in a frequency of 5 GHz. The IEEE 802.11ac standard is defined only in the 5GHz band, but the original 11ac chipset supports operation even in the 2.4GHz band for backward compatibility with existing 2.4GHz band products. Theoretically, according to this standard, the wireless LAN speeds of a plurality of stations can be made to be a minimum of 1Gbps, and the maximum single link speed can be made to be a minimum of 500Mbps. This is achieved by expanding the concept of the wireless interface received by 802.11n, such as wider wireless frequency bandwidth (max 160 MHz), more MIMO spatial streams (max 8), multi-user MIMO, and high density modulation (max 256 QAM). In addition, as a scheme for transmitting data by using a 60GHz band instead of the existing 2.4GHz/5GHz, IEEE 802.11ad has been provided. IEEE 802.11ad is a transmission standard that provides a maximum speed of 7Gbps by using a beamforming technique, and is suitable for high bit rate moving image streams such as large-scale data or uncompressed HD video. However, since the 60GHz band is difficult to pass through an obstacle, it has a disadvantage in that the 60GHz band can be used only among devices in a close space.
As wireless LAN standards after 802.11ac and 802.11ad, the IEEE 802.11ax (High Efficiency wireless LAN (HEW)) standard for providing efficient and High performance wireless LAN communication technology in a High density environment where APs and terminals are concentrated is in a development completion stage. In an 802.11 ax-based wireless LAN environment, in the presence of a high-density station and an Access Point (AP), communication with high frequency efficiency should be provided indoors/outdoors, and various technologies for realizing such communication have been developed.
In order to support new multimedia applications such as high definition video and real-time games, new wireless LAN standards have begun to be developed to increase the maximum transmission rate. In IEEE 802.11be extremely high throughput (Extremely High Throughput, EHT), which is the 7 th generation wireless LAN standard, standard development is underway with the aim of supporting transmission rates up to 30Gbps in the 2.4/5/6GHz band through a comparatively wide band, increased spatial streams, multi-AP cooperation, and the like.
Disclosure of Invention
Technical problem
An embodiment of the present invention is directed to a wireless communication method using multiple links and a wireless communication terminal using the same.
The technical problems to be achieved in the present specification are not limited to the above-mentioned technical problems, and other technical problems not mentioned can be clearly understood by those skilled in the art on the basis of the following description.
Solution method
A first Multi-link Device (MLD) according to the present invention, the first MLD comprising a plurality of stations operating on a plurality of links, respectively, wherein the first MLD comprises a processor, wherein the processor: receiving a beacon frame (beacon frame) over a first link of a first AP among a plurality of Access Points (APs) respectively operating on one or more links included in a second MLD, and associating with one or more APs among the plurality of APs based on the received beacon frame, wherein the beacon frame includes at least one neighbor AP information field (Neighbor AP Information field) associated with at least one AP among the plurality of APs other than the first AP and/or at least one AP not included in the second MLD, each of the at least one neighbor AP information field includes a neighbor AP TBTT offset subfield (Neighbor AP TBTT Offset subfield) indicating an offset between a time at which the beacon frame is transmitted (target beacon transmission time: target Beacon Transmission Time, TBTT) and a time at which an AP reported by the neighbor AP information field transmits a next frame, the AP TBTT offset subfield being set to a neighbor AP offset value capable of being represented by a maximum value of bits assigned to the neighbor AP in a range of bits of 0.
Further, in the present invention, the bit allocated to the neighbor AP TBTT offset subfield is 8 bits, and the maximum value is 255.
Further, in the present invention, when the value of the neighbor AP TBTT offset subfield is set to 254, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs or more than 254 TUs according to the AP corresponding to the neighbor AP TBTT offset subfield.
Further, in the present invention, when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs, and when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP not included in the MLD among the at least one AP not included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is greater than 254 TUs.
Further, in the present invention, the beacon frame can include a specific subfield related to capability (capability), and the specific subfield indicates whether the second MLD is a non-STR (NSTR) MLD that is an MLD that does not support simultaneous transmission and reception (Simultaneous Transmission and Reception, STR).
Further, in the present invention, when the second MLD is the NSTR MLD, an association (association) with the at least one AP other than the first AP or an update process of a parameter related to at least one link formed with the at least one AP included in the second MLD is performed only through the first link, and the first link is a primary link and the at least one link is a Non-primary link.
Further, in the present invention, when the second MLD is the NSTR MLD, at least one station associated with the at least one AP among the plurality of stations and a first station associated with the first AP through the first link apply a timing synchronization function (timing synchronization function, TSF) timer.
Further, in the present invention, a difference between a reference value of the time synchronization of the at least one link between the at least one AP and the first MLD and the time synchronization of the first link of the first AP is lower than a specific value.
Further, in the present invention, the processor: transmitting a Multi-link (ML) probe request frame only to the first AP of the plurality of APs, the Multi-link (ML) probe request frame (Probe Request Frame) for requesting information related to the at least one AP of the plurality of APs other than the first AP, and in response, receiving an ML probe response frame including information related to the at least one AP, wherein the ML probe request frame and the ML probe response frame include a Multi-link element (ML), the Multi-link element including STA profile sub-elements (sub-elements) corresponding to each of the at least one AP, the STA profile sub-elements including a full profile sub-field (Complete Profile subfield) indicating whether all information related to at least one link of the at least one AP is requested, the STA profile sub-elements of the ML probe response frame further including a beacon interval presence sub-field (Beacon Interval Present subfield) and a DTIM presence information sub-field (DTIM Information Present subfield).
Further, in the present invention, when the second MLD is the NSTR MLD and the full profile subfield indicates a request for all information, the beacon interval present subfield is set to a value indicating that no beacon interval subfield exists in the STA profile subelement, and the DTIM information present subfield is set to a value indicating that no DTIM information subfield exists in the STA profile subelement.
In addition, the invention also provides a method, which comprises the following steps: receiving a beacon frame through a first link of a first Access Point (AP) among a plurality of APs included in a second MLD, each of the APs operating on one or more links; and associating with one or more of the plurality of APs based on the received beacon frame, wherein the beacon frame includes at least one neighbor AP information field (Neighbor AP Information field) related to at least one of the plurality of APs other than the first AP and/or not included in at least one of the second MLD, each of the at least one neighbor AP information fields includes a neighbor AP TBTT offset subfield (Neighbor AP TBTT Offset subfield) indicating an offset between a time (target beacon transmission time: target Beacon Transmission Time, TBTT) at which the beacon frame is transmitted and a time at which an AP reported by the neighbor AP information field transmits a next beacon frame, and the neighbor AP TBTT offset subfield is set to a value other than the maximum value in a range of 0 to the maximum value that can be represented by bits allocated to the neighbor AP TBTT offset subfield.
Advantageous effects
An embodiment of the present invention provides a wireless communication method that effectively uses a plurality of links and a wireless communication terminal using the same.
The effects obtainable in the present invention are not limited to the above-described effects, and other effects not mentioned can be clearly understood by those skilled in the art to which the present invention pertains from the following description.
Drawings
Fig. 1 illustrates a wireless LAN system according to an embodiment of the present invention.
Fig. 2 illustrates a wireless LAN system according to another embodiment of the present invention.
Fig. 3 illustrates a configuration of a station according to an embodiment of the present invention.
Fig. 4 illustrates a configuration of an access point according to an embodiment of the present invention.
Fig. 5 schematically illustrates a process of setting up links for a station and an access point.
Fig. 6 illustrates a carrier sense multiple access (Carrier Sense Multiple Access, CSMA)/collision avoidance (Collision Avoidance, CA) method used in wireless LAN communication.
Fig. 7 illustrates an embodiment of a format of a PLCP protocol data unit (PLCP Protocol Data Unit, PPDU) for each of various standard generations.
Fig. 8 illustrates examples of various very high throughput (Extremely High Throughput, EHT) Physical Protocol Data Unit (PPDU) formats and methods for indicating the formats, according to an embodiment of the invention.
Fig. 9 illustrates a multi-link device (multi-link device) according to an embodiment of the present invention.
Fig. 10 illustrates a case where transmissions on different links are simultaneously performed in a multilink operation according to an embodiment of the present invention.
Fig. 11 illustrates one example of the content of a Beacon frame (Beacon frame) transmitted by an AP of the AP MLD and a target Beacon transmission time (target Beacon transmission time, TBTT) information field format (Information field format) included in a reduced neighbor report (Reduced Neighbor Report, RNR) element (element) according to an embodiment of the present invention.
Fig. 12 illustrates another example of a TBTT information field format according to an embodiment of the present invention.
Fig. 13 illustrates one example of a TBTT information length subfield (Information Length subfield) indicating a TBTT information field including an MLD AP TBTT Offset subfield (Offset subfield) according to an embodiment of the present invention.
Fig. 14 illustrates an example of a profile subelement (Per-STA Profile subelement) format of each STA according to an embodiment of the present invention.
Fig. 15 illustrates an example of a procedure in which Non-AP MLD of Non-simultaneous transmission and reception (Non-Simultaneous Transmission and Reception, NSTR) soft AP MLD setup updates Non-main link information according to an embodiment of the present invention.
Fig. 16 is a flowchart illustrating one example of a procedure in which a non-AP STA MLD associated with NSTR AP MLD updates parameters of a non-primary link according to an embodiment of the present invention.
FIG. 17 is an example of a format of an element according to an embodiment of the invention.
Fig. 18 illustrates an example of a procedure of setting (defining) a silence interval (quench interval) for a non-main link according to an embodiment of the present invention at NSTR AP MLD.
Fig. 19 illustrates one example of a method of NSTR AP MLD of performing a non-primary link channel switch in accordance with an embodiment of the present invention.
Fig. 20 is a flowchart illustrating one example of the operation of the non-AP MLD according to an embodiment of the present invention.
Detailed Description
The terms used in the present specification adopt general terms that are currently widely used by considering the functions of the present invention, but the terms may be changed according to the intention, habit, and appearance of new technology of those skilled in the art. Furthermore, in a particular case, there are terms arbitrarily selected by the applicant, and in this case, the meanings thereof will be explained in the corresponding description section of the present invention. Therefore, it should be understood that the terms used in the present specification should be analyzed not only based on the names of the terms but also based on the essential meaning of the terms and the contents of the entire specification.
Throughout the specification, when an element is referred to as being "coupled" to another element, it can be "directly coupled" to the other element or be "electrically coupled" to the other element via a third element. Furthermore, unless explicitly stated to the contrary, the word "comprising" will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. Furthermore, restrictions such as "or above" or below "based on particular thresholds may be replaced with" greater than "or" less than "respectively, as appropriate. Hereinafter, in the present invention, fields and subfields may be used interchangeably.
Fig. 1 illustrates a wireless LAN system according to an embodiment of the present invention.
The wireless LAN system includes one or more basic service sets (Basic Service Set, BSS), and the BSS represents a set of devices that are successfully synchronized with each other to communicate with each other. In general, BSSs may be divided into an infrastructure BSS (infrastructure BSS) and an Independent BSS (IBSS), and fig. 1 illustrates the infrastructure BSS therebetween.
As shown in fig. 1, the infrastructure BSS (BSS 1 and BSS 2) includes one or more stations (STA 1, STA2, STA3, STA4, and STA 5), access points (AP-1 and AP-2) as stations providing a distributed service (Distribution Service), and a distributed system (Distribution System, DS) connecting the plurality of access points (AP-1 and AP-2).
A Station (STA) is a predetermined device including a medium access control (Medium Access Control, MAC) compliant with the specifications of the IEEE 802.11 standard and a Physical Layer (Physical Layer) interface for wireless media, and broadly includes both a non-access point (non-AP) Station and an Access Point (AP). Further, in this specification, the term "terminal" may be used to refer to either a non-AP STA or an AP, or both. A station for wireless communication comprises a processor and a communication unit, and may further comprise a user interface unit and a display unit according to an embodiment. The processor may generate a frame to be transmitted via the wireless network or process a frame received via the wireless network, and further, perform various processes for controlling the station. Further, the communication unit is functionally connected to the processor and transmits and receives frames via a wireless network for the station. According to the present invention, a terminal may be used as a term including a terminal (UE).
An Access Point (AP) is an entity that provides Access to a Distributed System (DS) via a wireless medium for stations associated therewith. In an infrastructure BSS, communication among non-AP stations is performed in principle via an AP, but even allows direct communication among non-AP stations when the direct link is configured. Meanwhile, in the present invention, an AP is used as a concept including a personal BSS coordination point (Personal BSS Coordination Point, PCP), and may broadly include a concept including a central controller, a Base Station (BS), a node B, a Base transceiver system (Base Transceiver System, BTS), or a Station controller. In the present invention, an AP may also be referred to as a base station wireless communication terminal. Base station wireless communication terminals may be used as a broad term including AP, base station (base station), enode B (eNodeB, eNB) and Transmission Point (TP). In addition, the base station wireless communication terminal may include various types of wireless communication terminals that allocate communication medium (medium) resources and perform scheduling (scheduling) in communication with a plurality of wireless communication terminals.
Multiple infrastructure BSSs may be interconnected via a Distributed System (DS). In this case, the plurality of BSSs connected via the distributed system are referred to as an extended service set (Extended Service Set, ESS).
Fig. 2 illustrates an independent BSS, which is a wireless LAN system, according to another embodiment of the present invention. In the embodiment of fig. 2, the duplicate explanation of the same as fig. 1 or of the parts corresponding to the embodiment of fig. 1 will be omitted.
Since the BSS3 illustrated in fig. 2 is an independent BSS and does not include an AP, all stations STA6 and STA7 are not connected with the AP. An independent BSS is not allowed to access the distributed system and forms a self-contained network (self-contained network). In an independent BSS, the respective stations STA6 and STA7 may be directly connected to each other.
Fig. 3 illustrates a block diagram of a configuration of a station 100 according to an embodiment of the present invention. As illustrated in fig. 3, a station 100 according to an embodiment of the present invention may include a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.
First, the communication unit 120 transmits and receives wireless signals, such as wireless LAN packets, and the like, and may be embedded in the station 100 or provided as a peripheral. According to an embodiment, the communication unit 120 may comprise at least one communication module using different frequency bands. For example, the communication unit 120 may include communication modules having different frequency bands (such as 2.4GHz, 5GHz, 6GHz, and 60 GHz). According to an embodiment, station 100 may include a communication module using a frequency band of 7.125GHz or more and a communication module using a frequency band of 7.125GHz or less. 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 together at the same time, depending on the capabilities and requirements of the station 100. When station 100 includes a plurality of communication modules, each communication module may be implemented by a separate element, or the plurality of modules may be integrated into one chip. In an embodiment of the present invention, the communication unit 120 may represent an RF communication module for processing Radio Frequency (RF) signals.
Next, the user interface unit 140 includes various types of input/output devices provided in the station 100. That is, the user interface unit 140 may receive user inputs by using various input devices, and the processor 110 may control the station 100 based on the received user inputs. Further, the user interface unit 140 may perform output based on a command of the processor 110 by using various output devices.
Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects, such as content or a user interface executed by the processor 110, etc., based on control commands of the processor 110. Further, the memory 160 stores a control program and various data used in the station 100. The control procedure may include an access procedure required for the station 100 to access the AP or an external station.
The processor 110 of the present invention may execute various commands or programs and process data in the station 100. Further, the processor 110 may control various units of the station 100 and control data transmission/reception among the units. According to an embodiment of the present invention, the processor 110 may execute a program for accessing an AP stored in the memory 160 and receive a communication configuration message transmitted by the AP. Further, the processor 110 may read information on the priority condition of the station 100 included in the communication configuration 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 represent a main control unit of the station 100, and according to an embodiment, the processor 110 may represent a control unit for individually controlling certain components of the station 100 (e.g., the communication unit 120, etc.). That is, the processor 110 may be a modem or a modulator/demodulator (modulator/demodulator) for modulating a wireless signal transmitted to the communication unit 120 and demodulating a wireless signal received from the communication unit 120. Processor 110 controls various operations of wireless signal transmission/reception of station 100 according to an embodiment of the present invention. Detailed examples of which will be described below.
The station 100 illustrated in fig. 3 is a block diagram according to an embodiment of the invention, where separate blocks are illustrated as elements of logically distinct devices. Thus, the elements of the device may be mounted in a single chip or multiple chips depending on the design of the device. For example, the processor 110 and the communication unit 120 may be implemented when integrated as a single chip, or implemented as separate chips. Furthermore, in an embodiment of the present invention, certain components of the station 100, such as the user interface unit 140 and the display unit 150, etc., may be selectively provided in the station 100.
Fig. 4 illustrates a block diagram of a configuration of an AP 200 according to an embodiment of the present invention. As illustrated in fig. 4, an AP 200 according to an embodiment of the present invention may include a processor 210, a communication unit 220, and a memory 260. In fig. 4, among the components of the AP 200, the duplicate explanation of the same as the components of the station 100 of fig. 2 or the parts corresponding to the components of the station 100 of fig. 2 will be omitted.
Referring to fig. 4, an AP 200 according to the present invention includes a communication unit 220 operating a BSS in at least one frequency band. As illustrated in the embodiment of fig. 3, 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 (e.g., 2.4GHz, 5GHz, 6GHz, and 60 GHz) together. Preferably, the AP 200 may include a communication module using a frequency band of 7.125GHz or more, and a communication module using a frequency band of 7.125GHz or less. 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 simultaneously operate a plurality of communication modules together according to the performance and requirements of the AP 200. In an embodiment of the present invention, the communication unit 220 may represent a Radio Frequency (RF) communication module for processing an RF signal.
Next, the memory 260 stores a control program used in the AP 200 and various result data. The control procedure may comprise an access procedure for managing access by the station. Further, the processor 210 may control various units of the AP 200 and control data transmission/reception among the units. According to an embodiment of the present invention, the processor 210 may execute a program for accessing stations stored in the memory 260 and transmit communication configuration messages for one or more stations. In this case, the communication configuration message may include information on access priority conditions of the respective stations. Further, the processor 210 performs access configuration according to an access request of the station. According to an embodiment, the processor 210 may be a modem or a modulator/demodulator (modulator/demodulator) for modulating a wireless signal transmitted to the communication unit 220 and demodulating a wireless signal received from the communication unit 220. Processor 210 controls various operations, such as wireless signal transmission/reception by AP 200, according to an embodiment of the present invention. Detailed embodiments thereof will be described below.
Fig. 5 is a diagram schematically illustrating a procedure in which a STA sets up a link with an AP.
Referring to fig. 5, in a broad sense, a link between the STA 100 and the AP 200 is set via three steps of scanning (scanning), authentication (authentication), and association (association). First, the scanning step is a step in which the STA 100 obtains access information of a BSS operated by the AP 200. The method for performing scanning includes a passive scanning (passive scanning) method in which the AP 200 obtains information by using a periodically transmitted beacon (beacon) message (S101), and an active scanning (active scanning) method in which the STA 100 transmits a probe request (probe request) to the AP (S103) and obtains access information by receiving a probe response (probe response) from the AP (S105).
The STA 100 that successfully receives the wireless access information in the scanning step performs the authentication step by transmitting an authentication request (authentication request) (S107 a) and receiving an authentication response (authentication response) from the AP 200 (S107 b). After performing the authentication step, the STA 100 performs the association step by transmitting an association request (association request) (S109 a) and receiving an association response (association response) from the AP 200 (S109 b). In this specification, association basically refers to wireless association, but the present invention is not limited thereto, and association may broadly include both wireless association and wired association.
Meanwhile, an authentication step (S111) based on 802.1X and an IP address acquisition step (S113) via DHCP may be additionally performed. In fig. 5, the authentication server 300 is a server that handles 802.1X-based authentication of the STA 100, and may exist in physical association with the AP 200, or exist as a separate server.
Fig. 6 is a diagram illustrating a carrier sense multiple access (Carrier Sense Multiple Access, CSMA)/collision avoidance (Collision Avoidance, CA) method used in wireless LAN communication.
A terminal performing wireless LAN communication confirms whether a channel is in a busy state (busy) by performing carrier sensing before transmitting data. When a wireless signal having a preset intensity or more is sensed, a corresponding channel is determined to be in an occupied state (busy) and a terminal delays access to the corresponding channel. This procedure is referred to as clear channel assessment (Clear Channel Assessment, CCA), and the level of deciding whether a corresponding signal is sensed is referred to as a CCA threshold (CCA threshold). When a terminal receives a wireless signal having a CCA threshold or higher, the terminal instructs the corresponding terminal as a receiving side, the terminal processes the received wireless signal. Meanwhile, when no wireless signal is sensed in the corresponding channel or a wireless signal having an intensity less than the CCA threshold is sensed, it is determined that the channel is in an idle state (idle).
When it is determined that the channel is idle, each terminal having data to be transmitted performs a backoff procedure after an inter-frame space (Inter Frame Space, IFS) time, which depends on the condition of each terminal, for example, through an Arbitration IFS (AIFS), a PCF IFS (PIFS), etc. According to this embodiment, AIFS may be used as a component to replace existing DCF IFS (DIFS). Each terminal waits while reducing a slot time as long as a random number (random number) determined by the corresponding terminal during an interval (interval) of an idle state of a channel, and the terminal that completely exhausts the slot time attempts to access the corresponding channel. Thus, an interval in which each terminal performs the backoff procedure is referred to as a contention window interval.
When a particular terminal succeeds in channel access, the corresponding terminal may transmit data through the channel. However, when a terminal attempting access collides with another terminal, terminals that collide with each other are respectively assigned new random numbers to perform the backoff process again. According to an embodiment, the random number newly allocated to each terminal may be determined within a range (2×cw) that is twice the range (contention window CW) of the random number previously allocated to the corresponding terminal. Meanwhile, each terminal attempts access by performing a backoff procedure again in the next contention window interval, and in this case, each terminal performs the backoff procedure starting from the time slot time remaining in the previous contention window interval. In this way, the respective terminals performing wireless LAN communication can avoid collision of the special channels with each other.
Hereinafter, in the present invention, a terminal may be referred to as a non-AP STA, an STA, a receiving device, or a transmitting device, and the present invention is not limited thereto. Further, in the present invention, an AP STA may be referred to as an AP.
< examples of various PPDU formats >
Fig. 7 illustrates an example of a format of a PLCP protocol data unit (PLCP Protocol Data Unit, PPDU) for each of various standard generations. More specifically, fig. 7 (a) illustrates an embodiment of a legacy PPDU format based on 802.11a/g, fig. 7 (b) illustrates an embodiment of a HE PPDU format based on 802.11ax, and fig. 7 (c) illustrates an embodiment of a non-legacy PPDU (i.e., EHT PPDU) format based on 802.11 be. Fig. 7 (d) illustrates detailed field configurations of the RL-SIG and the L-SIG commonly used in the PPDU format.
Referring to fig. 7 (a), the preamble of the legacy PPDU includes a legacy short training field (Legacy Short Training field, L-STF), a legacy long training field (Legacy Long Training field, L-LTF), and a legacy signal field (Legacy Signal field, L-SIG). In embodiments of the invention, the L-STF, L-LTF, and L-SIG may be referred to as legacy preambles.
Ext> referringext> toext> fig.ext> 7ext> (ext> bext>)ext>,ext> theext> preambleext> ofext> theext> HEext> PPDUext> furtherext> includesext> aext> repetitionext> conventionalext> shortext> trainingext> fieldext> (ext> Repeatedext> Legacyext> Shortext> Trainingext> fieldext>,ext> RLext> -ext> SIGext>)ext>,ext> aext> highext> efficiencyext> signalext> aext> fieldext> (ext> Highext> Efficiencyext> Signalext> Aext> fieldext>,ext> HEext> -ext> SIGext> -ext> aext>)ext>,ext> aext> highext> efficiencyext> signalext> bext> fieldext> (ext> Highext> Efficiencyext> Signalext> Bext> fieldext>,ext> HEext> -ext> SIGext> -ext> bext>)ext>,ext> aext> highext> efficiencyext> shortext> trainingext> fieldext> (ext> Highext> Efficiencyext> Shortext> Trainingext> fieldext>,ext> HEext> -ext> stfext>)ext>,ext> andext> aext> highext> efficiencyext> longext> trainingext> fieldext> (ext> Highext> Efficiencyext> Longext> Trainingext> fieldext>,ext> HEext> -ext> ltfext>)ext> inext> theext> conventionalext> preambleext>.ext> In embodiments of the invention, the RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF may be referred to as HE preambles. The detailed configuration of the HE preamble may be modified according to the HE PPDU format. For example, the HE-SIG-B may be used only in the HE MU PPDU format.
Ext> referringext> toext> fig.ext> 7ext> (ext> cext>)ext>,ext> theext> EHText> PPDUext> furtherext> includesext> repeatedext> conventionalext> shortext> trainingext> fieldsext> (ext> Repeatedext> Legacyext> Shortext> Trainingext> fieldext>,ext> RLext> -ext> SIGext>)ext>,ext> generalext> signalext> fieldsext> (ext> Universalext> Signalext> fieldext>,ext> Uext> -ext> SIGext>)ext>,ext> andext> veryext> highext> throughputext> signalext> aext> fieldsext> (ext> Extremelyext> Highext> Throughputext> Signalext> Aext> fieldext>,ext> EHText> -ext> SIGext> -ext> aext>)ext>,ext> veryext> highext> throughputext> signalext> bext> fieldsext> (ext> Extremelyext> Highext> Throughputext> Signalext> Bext> fieldext>,ext> EHText> -ext> SIGext> -ext> bext>)ext>,ext> veryext> highext> throughputext> shortext> trainingext> fieldsext> (ext> Extremelyext> Highext> Throughputext> Shortext> Trainingext> fieldext>,ext> EHText> -ext> stfext>)ext>,ext> andext> veryext> highext> throughputext> longext> trainingext> fieldsext> (ext> Extremelyext> Highext> Throughputext> Longext> Trainingext> fieldext>,ext> EHText> -ext> ltfext>)ext> inext> theext> conventionalext> preambleext>.ext> In embodiments of the invention, the RL-SIG, EHT-SIG-A, EHT-SIG-B, EHT-STF, and EHT-LTF may be referred to as EHT preambles. The specific configuration of the non-legacy preamble may be modified according to the EHT PPDU format. Ext> forext> exampleext>,ext> theext> EHText> -ext> SIGext> -ext> Aext> andext> theext> EHText> -ext> SIGext> -ext> Bext> mayext> beext> usedext> inext> onlyext> aext> portionext> ofext> theext> EHText> PPDUext> formatext>.ext>
The 64-FFT OFDM is applied to the L-SIG field included in the preamble of the PPDU, and the L-SIG field includes 64 subcarriers in total. Of the 64 subcarriers, 48 subcarriers other than the guard subcarrier, the DC subcarrier, and the pilot subcarrier are used for transmission of the L-SIG data. The modulation and coding scheme (Modulation and Coding Scheme, MCS) of BPSK and code rate=1/2 is applied in the L-SIG, and thus the L-SIG may include a total of 24 bits of information. Fig. 7 (d) illustrates a configuration of 24-bit information of the L-SIG.
Referring to fig. 7 (d), the L-SIG includes an l_rate field and an l_length field. The l_rate field includes 4 bits and indicates an MCS for data transmission. Specifically, the l_rate field indicates one value of the transmission RATE of 6/9/12/18/24/36/48/54Mbps obtained by combining a modulation scheme of BPSK/QPSK/16-QAM/64-QAM or the like with inefficiency such as 1/2, 2/3, 3/4 or the like. The total LENGTH of the corresponding PPDU may be indicated by combining information of the l_rate field and information of the l_length field. In the non-legacy PPDU format, the l_rate field is configured to a minimum RATE of 6 Mbps.
The unit of the l_length field may be allocated a total of 12 bits per byte, up to 4095 may be signaled, and the LENGTH of the corresponding PPDU may be indicated by a combination with the l_rate field. In this case, the legacy terminal and the non-legacy terminal may interpret the l_length field using different methods.
First, a method in which a legacy terminal or a non-legacy terminal analyzes the LENGTH of a corresponding PPDU using an l_length field is as follows. When the value of the l_rate field is set to indicate 6Mbps, 3 bytes (i.e., 24 bits) may be transmitted during 4us, which is one symbol duration of the 64 FFT. Therefore, 3 bytes corresponding to the SVC field and the tail field are added to the value of the field l_length, and the added value is divided by 3 bytes which are the transmission amount of one symbol, thereby obtaining the number of 64 FFT-based symbols after the L-SIG. The obtained number of symbols is multiplied by 4us (i.e., the length of one symbol), and then the time required for transmission of the L-STF, the L-LTF, and the L-SIG is added by 20us, thereby obtaining the length of the corresponding PPDU, i.e., the reception time RXTIME. This can be expressed by the following equation 1.
[ equation 1]
In this case the number of the elements to be formed is,representing a minimum natural number greater than or equal to x. Since the maximum value of the l_length field is 4095, the LENGTH of the PPDU can be set to be as long as 5.464ms. The non-legacy terminal transmitting the PPDU should set the l_length field as shown in equation 2 below.
[ equation 2]
Here, TXTIME is a total transmission time constituting the corresponding PPDU, and is represented by the following equation 3. In this case, TX represents the transmission time of X.
[ equation 3]
TXTIME(us)＝T L-STF +T L-LTF +T L-SIG +T RL-SIG +T U - SIG +(T EHT-SIG-A )+(T EHT-SIG-B )+T EHT-STF +N EHT-LTF ·T EHT-LTF +T DATA
Referring to the above equation, the LENGTH of the PPDU is calculated based on the round-up value of l_length/3. Thus, for a random value of k, three different values of l_length= {3k+1,3k+2,3 (k+1) } indicate the same PPDU LENGTH.
Referring to (e) of fig. 7, a common SIG (U-SIG) field continues to exist in EHT PPDUs and wireless LAN PPDUs of the subsequent generation, and is used to classify the generation of PPDUs including 11 be. The U-SIG is a 64 FFT-based OFDM 2 symbol, and can transmit 52 bits of information in total. Of the 52 bits, 43 bits other than the CRC/tail 9 bits are mainly divided into a version independent (Version Independent, VI) field and a version dependent (Version Dependent, VD) field.
The VI bits enable the current bit configuration to be maintained later, so that the current 11be terminal can obtain information about the PPDU through the VI field of the PPDU even though the next generation PPDU is defined. To this end, the VI field includes PHY version, UL/DL, BSS color, TXOP, and reserved field. The PHY version field is 3 bits, and is used to sequentially classify 11be and subsequent generation wireless LAN standards into versions. The value of 11be is 000b. The UL/DL field identifies whether the PPDU is an uplink/downlink PPDU. The BSS color indicates an identifier of each BSS defined in 11ax, and has a value of 6 bits or more. The TXOP indicates a transmission opportunity duration (Transmit Opportunity Duration) of transmission at the MAC header, wherein the PPDU can infer a length of the TXOP included therein without decoding the MPDU by adding the TXOP to the PHY header, and the TXOP has a value of 7 bits or more.
The VD field is signaling information useful only for an 11be version of the PPDU, and may include a field commonly used in any PPDU format such as PPDU format and BW, and a field differently defined for each PPDU format. The PPDU format is a classifier that classifies EHT Single User (SU), EHT Multi User (MU), EHT based on Trigger (TB), EHT Extended Range (ER) PPDUs, and the like. The BW field signals five basic PPDU BW options (BW, which may be expressed in an exponent power type of 20 x 2, which may be referred to as basic BW) of 20, 40, 80, 160 (80+80), and 320 (160+160) MHz, and various remaining PPDUs BW configured via preamble puncturing (Preamble Puncturing). After signaling at 320MHz, signaling may be performed in some 80MHz punctured types. The punctured and modified channel type may be signaled directly in the BW field or may be signaled using the BW field and a field that occurs after the BW field (e.g., a field within the EHT-SIG field). If the BW field is configured to 3 bits, a total of 8 BW signaling may be performed, and thus only up to 3 signaling may be performed in the puncturing pattern. If the BW field is configured to 4 bits, a total of 16 BW signaling may be performed, and thus up to 11 signaling may be performed in the puncturing pattern.
The field located after the BW field varies according to the type and format of the PPDU, the MU PPDU and the SU PPDU may be signaled in the same PPDU format, the field for classifying between the MU PPDU and the SU PPDU may be located before the EHT-SIG field, and additional signaling may be performed on the field. Both the SU PPDU and MU PPDU include EHT-SIG fields, but some fields that are not needed in the SU PPDU may be compressed (compression). The information about the field to which compression has been applied may be omitted or may have a size smaller than that of the original field included in the MU PPDU. For example, in the case of a SU PPDU, the common field of the EHT-SIG may be omitted or replaced, or the SU PPDU may have a different configuration in which the user-specific field is replaced, reduced to one, or the like.
Alternatively, the SU PPDU may further include a compression field indicating whether compression is performed, and a part of a field (e.g., RA field, etc.) may be omitted according to a value of the compression field.
If a portion of the EHT-SIG field of the SU PPDU is compressed, information to be included in the compressed field may also be signaled in an uncompressed field (e.g., common field, etc.). The MU PPDU corresponds to a PPDU format for simultaneous reception by a plurality of users, and thus requires transmission of the EHT-SIG field after the U-SIG field, and the amount of information transmitted may vary. That is, a plurality of MU PPDUs are transmitted to a plurality of STAs such that each STA should identify the location of the RU to which the MU PPDU is transmitted, the STA to which the RU is respectively allocated, and whether the transmitted MU PPDU has been transmitted to the STA itself. Therefore, the AP should transmit the information by including the information in the EHT-SIG field. To this end, information for effective transmission of the EHT-SIG field is signaled in the U-SIG field, and this may correspond to the MCS and/or the number of symbols in the EHT-SIG field as a modulation method. The EHT-SIG field may include information about the size and location of the RU allocated to each user.
In the case of SU PPDUs, multiple RUs may be allocated to STAs, and may be contiguous or non-contiguous. If the RUs allocated to the STA are discontinuous, the STA should identify the middle punctured RU in order to effectively receive the SU PPDU. Accordingly, the AP may transmit a SU PPDU including information of a punctured RU among RUs allocated to the STA (e.g., a puncturing pattern of the RU, etc.). That is, in case of the SU PPDU, a puncturing pattern field including information indicating a puncturing pattern and whether or not the puncturing pattern is applied in a bitmap format or the like may be included in the EHT-SIG field, and the puncturing pattern field may signal a discontinuous channel type occurring within the bandwidth.
The signaled discontinuous channel type is limited and indicates BW and discontinuous channel information of the SU PPDU combined with the value of the BW field. For example, the SU PPDU is a PPDU transmitted to only a single terminal, so that the STA can identify a bandwidth allocated to itself via a BW field contained in the PPDU, and the SU PPDU can identify a puncturing resource in the allocated bandwidth via an EHT-SIG field or a puncturing pattern field of a U-SIG field contained in the PPDU. In this case, the terminal may receive the PPDU in the remaining resource units after excluding the special channel of the punctured resource unit. Multiple RUs allocated to a STA may be configured by different frequency bands or tones.
To reduce the signaling overhead of the SU PPDU, only a limited discontinuous channel type is signaled. Puncturing may be performed for each 20MHz subchannel so that if puncturing is performed for BW with a large number of 20MHz subchannels, such as 80, 160 and 320MHz, then in the case of 320MHz, the type of discontinuous channel (if puncturing for only the edge 20MHz is also considered discontinuous) should be signaled by indicating whether each of the remaining 15 20MHz subchannels is used after the primary channel is excluded. Thus, the discontinuous channel type of allocating 15 bits to signal a single user transmission may act as excessive signaling overhead in consideration of the low transmission rate of the signaling portion.
The present invention proposes a technique for signaling the discontinuous channel type of the SU PPDU and illustrates the discontinuous channel type determined according to the proposed technique. The present invention also proposes a technique for signaling each of the Primary (Primary) 160MHz and Secondary (Secondary) 160MHz puncture types in a 320MHz BW configuration of a SU PPDU.
Further, a technique of differently configuring a PPDU indicated by a preamble puncture BW value according to a PPDU format signaled in a PPDU format field is proposed in an embodiment of the present invention. Ext>ext> assumingext>ext> thatext>ext> theext>ext> BWext>ext> fieldext>ext> isext>ext> 4ext>ext> bitsext>ext>,ext>ext> andext>ext> inext>ext> theext>ext> caseext>ext> ofext>ext> anext>ext> EHText>ext> SUext>ext> PPDUext>ext> orext>ext> TBext>ext> PPDUext>ext>,ext>ext> anext>ext> EHText>ext> -ext>ext> SIGext>ext> -ext>ext> aext>ext> ofext>ext> 1ext>ext> symbolext>ext> mayext>ext> beext>ext> additionallyext>ext> signaledext>ext> afterext>ext> theext>ext> Uext>ext> -ext>ext> SIGext>ext> orext>ext> notext>ext> signaledext>ext> atext>ext> allext>ext>,ext>ext> soext>ext> itext>ext> isext>ext> necessaryext>ext> toext>ext> completelyext>ext> signalext>ext> upext>ext> toext>ext> 11ext>ext> puncturingext>ext> patternsext>ext> onlyext>ext> viaext>ext> theext>ext> BWext>ext> fieldext>ext> ofext>ext> theext>ext> Uext>ext> -ext>ext> SIGext>ext> inext>ext> viewext>ext> ofext>ext> thisext>ext>.ext>ext> However, in the case of the EHT MU PPDU, the EHT-SIG-B is additionally signaled after the U-SIG, so that up to 11 puncturing patterns can be signaled in a different method from that of the SU PPDU. In the case of an EHT ER PPDU, the BW field may be configured to be 1 bit to signal whether the EHT ER PPDU uses a 20MHz band or a 10MHz band PPDU.
Fig. 7 (f) illustrates a configuration of a Format specific (Format-specific) field of the VD field when an EHT MU PPDU is indicated in a PPDU Format field of the U-SIG. Ext> inext> theext> caseext> ofext> MUext> PPDUsext>,ext> SIGext> -ext> Bext> isext> necessarilyext> requiredext>,ext> whichext> isext> aext> signalingext> fieldext> forext> simultaneousext> receptionext> byext> multipleext> usersext>,ext> andext> SIGext> -ext> Bext> mayext> beext> transmittedext> afterext> Uext> -ext> SIGext> withoutext> separateext> SIGext> -ext> aext>.ext> For this purpose, the information for decoding SIG-B should be signaled in the U-SIG. These fields include the SIG-B MCS, SIG-B DCM, the number of SIG-B symbols, SIG-B compression, the number of EHT-LTF symbols, etc.
Fig. 8 illustrates examples of various very high throughput (Extremely High Throughput, EHT) Physical Protocol Data Unit (PPDU) formats and methods for indicating the formats, according to an embodiment of the invention.
Referring to fig. 8, the PPDU may include a preamble (preamble) and a data portion, and may be classified into an EHT PPDU format as a PPDU type according to a U-SIG field included in the preamble. Specifically, based on a PPDU format field included in the U-SIG field, it may be indicated whether the format of the PPDU is an EHT PPDU.
Fig. 8 (a) illustrates an example of an EHT SU PPDU format for a single STA. Ext> theext> EHText> SUext> PPDUext> isext> aext> PPDUext> forext> Singleext> Userext> (ext> SUext>)ext> transmissionext> betweenext> anext> APext> andext> aext> Singleext> STAext>,ext> andext> anext> EHText> -ext> SIGext> -ext> aext> fieldext> forext> additionalext> signalingext> mayext> beext> locatedext> afterext> theext> uext> -ext> SIGext> fieldext>.ext>
Fig. 8 (b) illustrates an example of an EHT trigger-based PPDU format corresponding to an EHT PPDU transmitted based on a trigger frame. The EHT trigger-based PPDU is an EHT PPDU based on trigger frame transmission and is an uplink PPDU for a response to a trigger frame. Ext> unlikeext> theext> EHText> SUext> PPDUext>,ext> theext> EHText> -ext> SIGext> -ext> Aext> fieldext> isext> notext> locatedext> afterext> theext> Uext> -ext> SIGext> fieldext> inext> theext> EHText> PPDUext>.ext>
Fig. 8 (c) illustrates an example of an EHT MU PPDU format corresponding to EHT PPDUs of a plurality of users. An EHT MU PPDU is a PPDU used to transmit a PPDU to one or more STAs. In the EHT MU PPDU format, the HE-SIG-B field may be located after the U-SIG field.
Fig. 8 (d) illustrates an example of an EHT ER SU PPDU format for single user transmission with STAs within an extended range. In comparison with the EHT SU PPDU illustrated in (a) of fig. 8, the EHT ER SU PPDU can be used for single user transmission with a wider range of STAs, and the U-SIG field can be relocated on the time axis.
The EHT MU PPDU illustrated in (c) of fig. 8 may be used by the AP to perform downlink transmission toward a plurality of STAs. Here, the EHT MU PPDU may include scheduling information such that a plurality of STAs may simultaneously receive PPDUs transmitted from the AP. The EHT MU PPDU may transmit AID information of a sender and/or a receiver of the PPDU transmitted via a user specific (user specific) field of the EHT-SIG-B to the STA. Accordingly, a plurality of terminals having received the EHT MU PPDU may perform a spatial reuse (spatial reuse) operation based on AID information of a user-specific field included in a preamble of the received PPDU.
In particular, a resource unit allocation (resource unit allocation, RA) field of the HE-SIG-B field included in the HE MU PPDU may include information about a configuration (e.g., a division type of the resource unit) of the resource unit in a special bandwidth (e.g., 20MHz, etc.) of the frequency axis. That is, the RA field may indicate a configuration of resource units divided in a bandwidth for transmission of the HE MU PPDU so that the STA receives the PPDU. Information about STAs allocated (or designated) to each of the divided resource units may be included in a user-specific field of the EHT-SIG-B so as to be transmitted to the STAs. That is, the user-specific field may include one or more user fields corresponding to respective partitioned resource units.
For example, a user field corresponding to at least one resource unit for data transmission among a plurality of divided resource units may include an AID of a receiver or a transmitter, and a user field corresponding to the remaining resource units not used for data transmission may include a pre-configured Null (Null) STA ID.
For ease of description, in this specification, a frame or MAC frame may be used interchangeably with MPDU.
When one wireless communication device communicates using a plurality of links, the communication efficiency of the wireless communication device can be improved. In this case, the link is a physical path (path) which may be formed by a radio medium that can be used to deliver MAC service data units (MAC service data unit, MSDUs). For example, when the frequency band of one link is used by another wireless communication device, the wireless communication device may continue to communicate over the other link. In this way, the wireless communication device can efficiently utilize multiple channels. In addition, when the wireless communication device communicates using a plurality of links at the same time, the total throughput (throughput) can also be improved. However, in the conventional wireless LAN, provision is made on the premise that one wireless communication apparatus uses one link. Therefore, a wireless LAN operating method using multiple links is required. Referring to fig. 9 to 26, a wireless communication method of a wireless communication apparatus using a plurality of links will be described. First, a specific form of a wireless communication device using a plurality of links will be described with reference to fig. 9.
Fig. 9 illustrates a multi-link device (multi-link device) according to an embodiment of the present invention.
For the above-described wireless communication method using a plurality of links, a multi-link device (MLD) may be defined. A multi-link device may represent a device having one or more attached (afiiated) stations. According to particular embodiments, a multi-link device may represent a device having two or more secondary stations. Furthermore, the multilink devices may exchange multilink elements. The multilink element includes information about one or more stations or one or more links. The multilink element may include a multilink setting element, which will be described later. In this case, the multilink device may be a logical entity (entity). In particular, a multilink device may have multiple secondary stations. The multi-link device may be referred to as a multi-link logical entity (MLLE) or a multi-link entity (MLE). The multi-link device may have one MAC service access point (medium access control service access point, SAP) up to Logical Link Control (LLC). In addition, the MLD may have one MAC data service.
Multiple stations included in a multi-link device may operate on multiple links. Further, a plurality of stations included in the multi-link device may operate on a plurality of channels. In particular, a plurality of stations included in the multi-link device may operate on a plurality of links different from each other or a plurality of channels different from each other. For example, a plurality of stations included in the multi-link device may operate on a plurality of channels different from each other of 2.4GHz, 5GHz, and 6 GHz.
The operation of a multi-link device may be referred to as multi-link operation, MLD operation, or multi-band operation. Further, when a station attached to a multi-link device is an AP, the multi-link device may be referred to as an AP MLD. In addition, when a station attached to a multi-link device is a non-AP station, the multi-link device may be referred to as a non-AP MLD.
Fig. 9 illustrates communication operations of the non-AP MLD and the AP-MLD. Specifically, the non-AP MLD and the AP-MLD each communicate using three links. The AP MLD includes a first AP (AP 1), a second AP (AP 2), and a third AP (AP 3). The non-AP MLD includes a first non-AP STA (non-AP STA 1), a second non-AP STA (non-AP STA 2), and a third non-AP STA (non-AP STA 3). The first AP (AP 1) and the first non-AP STA (non-AP STA 1) communicate via a first Link 1. Further, the second AP (AP 2) and the second non-AP STA (non-AP STA 2) communicate through a second Link 2. Further, the third AP (AP 3) and the third non-AP STA (non-AP STA 3) communicate through a third Link (Link 3).
The multilink operation may include a multilink setup (setup) operation. The multilink setup operation corresponds to the association operation of the single link operation described previously, which may need to be prioritized before frames are exchanged over the multilink. The multilink device may acquire information required for the multilink setting from the multilink setting element. In particular, the multilink settings element may include capability information associated with the multilink. In this case, the capability information may include information indicating whether or not any one of the plurality of devices included in the multi-link device can perform transmission while causing another device to perform reception. Further, the capability information may include information about links available to each station included in the MLD. Further, the capability information may include information on channels available to each station included in the MLD.
The multilink settings may be established through negotiations between peer stations. In particular, the multilink setup may be performed through communication between stations without communicating with the AP. In addition, the multilink setting may be established through any one of the links. For example, even in the case of setting the first link to the third link through the multilink, the multilink setting can be performed through the first link.
In addition, a mapping between traffic identifiers (traffic identifier, TID) and links may also be set. In particular, frames corresponding to a certain value of TID may be exchanged only through a predetermined link. The mapping between TID and link may be directional-based. For example, when a plurality of links are established between a first multi-link device and a second multi-link device, the first multi-link device may be configured to transmit frames with a first TID on a first link of the plurality of links, and the second multi-link device may be configured to transmit frames with a second TID on the first link. Furthermore, there may be default settings for the mapping between TID and links. In particular, without additional settings in the multilink settings, the multilink device may exchange frames corresponding to TIDs on the individual links according to default settings. In this case, the default setting may be to exchange all TIDs on a certain link.
The TID will be described in detail below. TID is an ID used to classify traffic and data to support quality of service (quality of service, qoS). In addition, TID may be used or allocated at a higher layer than the MAC layer. In addition, TID may represent Traffic Category (TC) and Traffic Stream (TS). In addition, TIDs can be distinguished as 16. For example, the TID may be designated as any one from 0 to 15. Different TID values may be specified depending on access policy (access policy), channel access or medium access method. For example, when enhanced distributed channel access (enhanced distributed channel access, EDCA) or hybrid coordination function contention-based channel access (hybrid coordination function contention based channel access, HCAF) is used, TID values of 0 to 7 may be assigned. When EDCA is used, TID may represent User Priority (UP). In this case, UP may be specified according to TC or TS. UP may be allocated at a higher layer than MAC. In addition, TID values of 8 to 15 may be assigned when HCF controlled channel access (HCF controlled channel access, HCCA) or SPCA is used. When HCCA or SPCA is used, TID may represent TSID. Further, when HEMM or SEMM is used, TID values of 8 to 15 may be assigned. When HEMM or SEMM is used, TID may represent TSID.
The UP and AC may map to each other. The AC may be a label used in EDCA to provide QoS. The AC may be a tag for indicating the EDCA parameter set. The EDCA parameter or EDCA parameter set is a parameter for EDCA channel contention (content). QoS stations may use AC to guarantee QoS. In addition, AC may include ac_bk, ac_be, ac_vi, and ac_vo. Ac_bk, ac_be, ac_vi, and ac_vo may represent background (background), best effort (best effort), video (video), and voice (voice), respectively. In addition, ac_bk, ac_be, ac_vi, and ac_vo may BE classified as sub AC. For example, ac_vi may be subdivided into ac_vi primary (primary) and ac_vi backup (alternate). In addition, ac_vo can be subdivided into ac_vo primary (primary) and ac_vo standby (alternate). Further, UP or TID may be mapped to AC. For example, 1, 2, 0, 3, 4, 5, 6, 7 of UP or TID may BE mapped to ac_bk, ac_be, ac_vi, ac_vo, and ac_vo, respectively. Further, 1, 2, 0, 3, 4, 5, 6, and 7 of UP or TID may BE mapped to AC_BK, AC_BE, AC_VI standby, AC_VI active, AC_VO active, and AC_VO standby, respectively. Further, 1, 2, 0, 3, 4, 5, 6, and 7 of UP or TID may be arranged in order of higher priority. I.e. 1 is low priority and 7 is high priority. Thus, ac_bk, ac_be, ac_vi, and ac_vo may have higher priority in order. In addition, ac_bk, ac_be, ac_vi, and ac_vo may correspond to AC indexes (AC indexes, ACI) of 0, 1, 2, and 3, respectively. Because of these characteristics of TID, the mapping between TID and link may represent the mapping between AC and link. Further, the mapping of links to AC may represent a mapping between TIDs and links.
As previously described, TIDs may be mapped to each of a plurality of links. In the mapping, a particular TID or AC may be assigned a link that is capable of exchanging the corresponding traffic. In addition, TID or AC may be specified that is transmissible in each transmission direction within the link. As previously mentioned, there may be default settings for the mapping between TID and link. In particular, without additional settings in the multilink settings, the multilink device may exchange frames corresponding to TIDs on the individual links according to default settings. In this case, the default setting may be to exchange all TIDs on a certain link. At any point in time, any TID or AC may always map to at least one link. Management frames and control frames may be transmitted on all links.
When a link is mapped to a TID or AC, only data frames corresponding to the TID or AC mapped to the link may be transmitted on the link. Thus, when a link is mapped to a TID or AC, no data frames corresponding to TID or AC not mapped to the link can be transmitted on the link. When a link is mapped to a TID or AC, an ACK may also be transmitted based on the link to which the TID or AC is mapped. For example, a block ACK protocol (agreement) may be determined based on a mapping between TIDs and links. In another particular embodiment, the mapping between TID and link may be determined based on a block ACK protocol. Specifically, the block ACK protocol may be set for TID mapped to a particular link.
QoS can be guaranteed by the mapping between TID and link described above. In particular, higher priority ACs or TIDs may map to links with relatively fewer operator stations or better channel conditions. In addition, the station can be maintained in a power saving state for a longer period of time by the above-described mapping between TIDs and links.
Fig. 10 illustrates a case where transmissions on different links are simultaneously performed in a multilink operation according to an embodiment of the present invention.
Depending on the implementation of the multi-link device, simultaneous operation on multiple links may not be supported. For example, a multi-link device may not support simultaneous transmission over multiple links, simultaneous reception over multiple links, or simultaneous transmission over one link while reception is being performed over another link. This is because the reception or transmission performed on one link may affect the reception or transmission performed on the other link. In particular, transmissions on one link may interfere with another link. Interference of one link to another link in a multi-link device may be referred to as internal leakage (internal leakage). The smaller the frequency spacing between links, the greater the internal leakage may become. In the case where the internal leakage is not particularly large, transmission may be performed on one link while transmission is performed on the other link. In the case where the internal leakage is large, it may be impossible to perform transmission on one link while performing transmission on the other link. The case where the multi-link device performs operations on multiple links simultaneously in this manner may be referred to as simultaneous transmission and reception (simultaneous transmit and receive, simultaneous transmission and reception, STR). For example, a case where a multi-link device transmits on multiple links simultaneously, or transmits on one link and receives on another link simultaneously, or receives on multiple links simultaneously, may be referred to as STR.
As previously described, the multi-link device may support STRs, or may support STRs only to a limited extent. In particular, the multi-link device may support STRs only under certain conditions. For example, when a multi-link device operates with a single radio (single radio), the multi-link device may not be able to perform STR. Furthermore, when the multi-link device operates using a single antenna, the multi-link device may not be able to perform STR. Further, when an internal leak is detected to be above a predetermined size, the multi-link device may not be able to perform STR.
A station may exchange information regarding the STR capabilities of the station with other stations. In particular, a station may exchange information with other stations as to whether the station's ability to perform transmission on multiple links simultaneously or to perform reception on multiple links simultaneously is limited. In particular, the information about whether the capability of performing transmission or reception on a plurality of links is limited may indicate whether transmission on a plurality of links at the same time, reception on a plurality of links at the same time, or both transmission and reception are performed at the same time. Further, the information on whether the capability of performing transmission or reception on the plurality of links is limited may be information indicated by a level. In particular, the information on whether the capability of performing transmission or reception on the plurality of links is limited may be information indicating a level representing the size of the internal leakage. In a specific embodiment, the information indicating the level representing the magnitude of the internal leakage may be information indicating the level representing the magnitude of the interference caused by the internal leakage. In another specific embodiment, it may be information indicating a level representing a frequency interval between links capable of causing an internal leakage influence. Further, the information indicating the level representing the magnitude of the internal leakage may be information indicating the relationship between the frequency interval between links and the magnitude of the internal leakage by level.
In fig. 10, a first station (STA 1) and a second station (STA 2) are attached (affile) to a non-AP multilink device. Further, the first AP (AP 1) and the second AP (AP 2) may be affiliated with one non-AP multilink device. A first link (link 1) is provided between the first AP (AP 1) and the first station (STA 1), and a second link (link 2) is provided between the second AP (AP 2) and the second station (STA 2). In fig. 10, a non-AP multi-link device may perform STR in a limited manner. When the second station (STA 2) performs transmission on the second Link (Link 2), the reception of the first station (STA 1) on the first Link (Link 1) may be interfered by the transmission performed on the second Link (Link 2). For example, in the following case, the reception of the first station (STA 1) on the first Link (Link 1) may be interfered by the transmission on the second Link (Link 2). On the second Link2, the second station (STA 2) transmits the first Data (Data 1), and the first AP (AP 1) transmits a response (Ack for Data 1) for the first Data (Data 1) to the first station (STA 1). On the second Link2, the second station (STA 2) transmits second Data (Data 2). At this time, the transmission time of the second Data (Data 2) and the transmission time of the response (Ack for Data 1) to the first Data (Data 1) may overlap. At this time, the transmission of the second station (STA 2) on the second Link (Link 2) may cause interference to the first Link (Link 1). Therefore, the first station (STA 1) may not receive the response (Ack for Data 1) for the first Data (Data 1).
The operation of the multi-link device to perform channel access is described below. Operation of the multilink device, not specifically described, may follow the channel access procedure described in fig. 6.
A multi-link device may independently perform channel access over multiple links. In this case, the channel access may be a back-off based channel access. When the multi-link device independently performs channel access on multiple links and the backoff counter on the multiple links reaches 0, the multi-link device may begin transmitting on multiple links simultaneously. In a specific embodiment, when one of the back-off counters of the links of the multi-link device reaches 0 and a predetermined condition is satisfied, the multi-link device may perform channel access on the link where the back-off counter reaches 0 and other links where the back-off counter does not reach 0. Specifically, when one of the backoff counters of the links of the multi-link device reaches 0, the multi-link device may perform energy detection on other links for which the backoff counter does not reach 0. At this time, if energy of a predetermined magnitude or more is not detected, the multi-link device may perform channel access on a link where the back-off counter reaches 0 and on a link where energy detection is performed. In this way, the multilink device can begin transmitting on multiple links simultaneously. The threshold size for energy detection may be smaller than the threshold size for determining whether to decrease the back-off counter. Further, the multi-link device may detect any type of signal, not just a wireless LAN signal, in determining whether to decrease the back-off counter. Further, in the above-described energy detection, the multi-link device may detect any form of signal, not just a wireless LAN signal. Internal leakage may not be detected by the wireless LAN signal. In this case, the multi-link device may use energy detection to sense signals detected due to internal leakage. Further, as previously described, the threshold size for energy detection may be smaller than the threshold size for determining whether to decrease the back-off counter. Therefore, even if transmission is being performed on one link, the multi-link device can reduce the backoff counter on the other link.
Depending on the level of interference between the links used by the multi-link device, the multi-link device may determine whether stations operating on each link may operate independently. In this case, the degree of interference between links may be the magnitude of interference detected by other stations of the multi-link device when a certain station of the multi-link device performs transmission on a certain link. Operation of a second station of a multi-link device operating on a second link may be limited when transmissions by the first station of the multi-link device on the first link cause interference above a predetermined magnitude to the second station. In particular, the reception or channel access of the second station may be limited. This is because, when interference occurs, the second station may fail to decode the received signal due to the interference. Further, this is because, in the event of interference, when the second station accesses the channel using the backoff mechanism, the second station may determine that the channel is in use.
Further, a first station and a second station of a multi-link device may operate independently when a transmission on the first link by the first station causes less than a predetermined amount of interference to a second station of the multi-link device operating on the second link. In particular, a first station and a second station of a multi-link device may independently perform channel access when a transmission on the first link by the first station causes less than a predetermined amount of interference to a second station of the multi-link device operating on the second link. Further, the first station and the second station may independently perform transmission or reception when a transmission of the first station of the multi-link device on the first link causes less than a predetermined size of interference to the second station of the multi-link device operating on the second link. This is because, when interference smaller than a predetermined size occurs, the second station can successfully decode the received signal even if interference exists. Further, this is because, in the case where interference smaller than a predetermined size occurs, when the second station accesses the channel using the backoff mechanism, the second station may determine that the channel is in an idle state.
The degree of interference between stations of a multi-link device may vary due to the hardware characteristics of the multi-link device and the spacing between the link bands in which the stations operate. For example, internal interference generated in a multi-link device containing an expensive Radio Frequency (RF) device may be less than internal interference generated in a multi-link device including a low cost RF device. Thus, the degree of interference generated between stations of the multi-link device may be determined based on the characteristics of the multi-link device.
Fig. 10 illustrates a case where the degree of interference is generated varies according to the interval between frequency bands of links and the characteristics of a multi-link device. In the embodiment of fig. 10, the first multi-Link device (mld#1) includes a first station (STA 1-1) operating on a first Link (Link 1) and a second station (STA 1-2) operating on a second Link (Link 2). The second multi-Link device (MLD#2) includes a first station (STA 2-1) operating on a first Link (Link 1) and a second station (STA 2-2) operating on a second Link (Link 2). The frequency interval between the first Link1 and the second Link2 operated by the first multi-Link device (mld#1) is the same as the frequency interval between the first Link1 and the second Link2 operated by the second multi-Link device (mld#2). However, the magnitude of interference generated by 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. Specifically, 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). Considering that the magnitude of interference generated may be different according to characteristics of the multi-link devices, and whether each multi-link device supports STRs may be different, it is necessary to exchange information about whether STRs are supported.
The multi-link device may signal information whether a station included in the multi-link device supports STR. Specifically, an AP link device and a non-AP multilink device may exchange AP multilink settingsInformation is provided as to whether the included AP supports STR and whether the STA included in the non-AP multi-link device supports STR. In these embodiments, an element may be used that indicates whether STR is supported. An element that indicates whether STR is supported may be referred to as an STR support element. The STR support element may indicate whether a station of the multi-link device transmitting the STR support element supports STR by 1 bit. In particular, the STR support element may indicate whether each station of the multi-link device transmitting the STR support element supports STR in one bit, respectively. If the station supports STR, the bit value is 1, and if the station does not support STR, the bit value is 0. If the multi-link device transmitting the STR support element includes a first station (STA 1), a second station (STA 2), and a third station (STA 3), and the first station (STA 1) and the third station (STA 3) support STR, and the second station (STA 2) does not support STR, the STR support element may include a data transmission system having a structure of 101 1b Is a field of (c). Stations operating on different frequency bands are assumed to support STRs, and the STR support element may omit signaling about whether an STR is supported or not between stations operating on different frequency bands. For example, a first station (STA 1) operates on a first link of 2.4GHz, and a second station (STA 2) and a third station (STA 3) operate on a second link and a third link of 5GHz, respectively. In this case, the STR support element may use one bit to represent support of STR between the second station (STA 2) and the third station (STA 3). Furthermore, if the STR support element signals 2 stations, the STR support element may include only one bit.
In particular embodiments, the relationship between links at 2.4GHz and links at 5GHz or 6GHz among links of a multi-link device may always be determined as STR. Thus, signaling as to whether the link at 2.4GHz and the link at 5GHz or 6GHz are STRs may be omitted.
In the above-described embodiments, the operation of the station of the multilink device may be replaced by the operation of the multilink device. Further, in the above-described embodiments, the operation of the AP may be replaced by the operation of the non-AP station, and the operation of the non-AP station may be replaced by the operation of the AP. Thus, the operation of the AP of the non-STR multilink device may be replaced by the operation of the non-AP station of the non-STR multilink device, and the operation of the non-AP station of the STR multilink device may be replaced by the operation of the AP of the STR multilink device. Further, operation of the non-AP station of the non-STR multilink device may be replaced by operation of the AP of the non-STR multilink device, and operation of the AP of the STR multilink device may be replaced by operation of the non-AP station of the STR multilink device.
Fig. 11 illustrates one example of Beacon frame (Beacon frame) content transmitted by an AP of the AP MLD and a target Beacon transmission time (target Beacon transmission time, TBTT) information field format (Information field format) included in a reduced neighbor report (Reduced Neighbor Report, RNR) element (element) according to an embodiment of the present invention.
Referring to fig. 11 (a), the beacon frame may include the same parameters and elements in the legacy IE as those included in the beacon frame disclosed in the legacy Wi-Fi 802.11 ax. For example, the legacy IE of the beacon frame may include elements such as a Timestamp field (Timestamp field), a beacon interval field (Beacon Interval field) indicating an interval in which the beacon is transmitted, TIM, DSSS parameter set (parameter set), IBSS parameter set, country, channel switch announcement (channel switch announcement), extended channel switch announcement, wideband channel switch, transmit power envelope (transmit power envelop), supported operation category (supporte operating classes), IBSS dfs, ERP information, HT capabilities (HT capabilities), HT operation, VHT capabilities, VHT operation, S1G beacon compatibility (compatibility), short beacon interval, S1G capability, S1G operation, HE capability, HE 6GHz band capability, HE operation, BSS color change announcement (BSS color change announcement), and spatial reuse parameter set (spatial reuse parameter set).
In this case, the setting method and meaning of the fields and elements included in the legacy IE field are the same as those included in the beacon frame disclosed in 802.11ax up to the legacy Wi-Fi.
In addition, the beacon frame may include a reduced neighbor report (Reduced Neighbor Report, RNR) element for information indicating neighbor (neighbor) APs. The RNR element may be used to inform the station of the neighbor AP's information, and the station may receive the beacon frame and identify the neighbor AP through the RNR element included in the beacon frame.
In particular, the RNR element may include an element ID field, a length field, and a neighbor AP information field. Each neighbor AP information field may include a TBTT information header (2 octets), an operation class (1 octet), a channel number (1 octet), and a TBTT information set (variable length) field. In this case, the RNR element transmitted by the AP included in the AP MLD may include the TBTT information field format shown in (b) of fig. 11 to indicate basic information about another AP included in the same MLD. Unlike the TBTT information field in the RNR element transmitted by the AP in 802.11ax of legacy Wi-Fi, the RNR element transmitted by the AP included in the EHT AP MLD may include an MLD parameter field.
As shown in fig. 11 (c), the MLD parameter field may include an MLD ID, a link ID, and a change sequence subfield. In this case, when the AP MLD indicates information about another AP in the same MLD through a specific neighbor AP information field in the RNR element, an MLD ID subfield included in the specific neighbor AP information field may be set to 0. That is, the AP may set the MLD ID subfield to a specific value in order to inform the station that the neighbor AP information field indicates that it is an AP included in the same AP MLD, and the station that receives the neighbor AP information field may recognize that the AP corresponding to the neighbor AP information field is included in the same MLD as the AP that transmits the neighbor AP information field through the value of the MLD ID subfield.
The link ID subfield may be a subfield indicating an index determined by the AP MLD to indicate a link operated by another AP to be indicated by neighbor AP information. The change sequence subfield may be a subfield for indicating update (e.g., critical update) information about a link with another AP. For example, when the value of a change sequence subfield changes, a station receiving the subfield may recognize that a parameter related to the link of the AP has been updated and may request the updated parameter from the AP in order to update the parameter. In this case, if the AP MLD is NSTR AP MLD, i.e., does not support MLD simultaneously transmitted and received (e.g., if the AP MLD is an NSTR mobile AP MLD or an NSTR soft AP MLD, i.e., a mobile terminal or the like operates as a soft AP MLD for network sharing (warming) or the like), an STA included in the STA MLD may perform a procedure for updating parameters only through a primary link (primary link). That is, in order to update parameters of other links (e.g., non-main links) of other neighbor APs than the main link of the AP MLD, frames for updating the parameters may be transmitted and received only through the main link.
Hereinafter, NSTR AP MLD may be referred to as NSTR softap MLD or NSTR mobile AP MLD in the present invention.
Further, if the AP is NSTR AP MLD that does not support simultaneous transmission and reception (e.g., if it is NSTR mobile AP MLD or NSTR soft AP MLD, i.e., the mobile terminal or the like operates as soft AP MLD for network sharing (warming), etc.), NSTR AP MLD may include information in the beacon frame indicating itself is NSTR AP MLD for transmission. For example, NSTR AP MLD may set the value of a particular subfield included in the beacon frame to a particular value (e.g., "0" or "1"), and the non-AP STA MLD receiving the beacon frame may recognize that the AP MLD transmitting the beacon frame is NSTR AP MLD. Thus, in the case that the specific subfield for indicating that it is NSTR AP MLD does not indicate NSTR AP MLD (e.g., STR AP MLD or other AP MLD, etc.), it may be set to a value (e.g., "1" or "0") different from the specific value.
The specific subfield indicating that it is NSTR AP MLD may be indicated along with a Capability (Capability) related subfield (e.g., MLD level Capability) in the beacon frame or may be included in a neighbor AP information field related to the AP of the non-main link of NSTR AP MLD for transmission. For example, a specific subfield for indicating that it is NSTR AP MLD may be encoded together with a frequency separation type indicator (Frequency Separation For STR/AP MLD Type Indication) of the STR/AP MLD type as a capability related subfield. That is, a specific subfield may be encoded with a frequency separation type indicator representing a STA/AP MLD type for supporting a distance of STR and indicated by a beacon frame. In this case, if the indicator indicates the type of the AP MLD, it may indicate that the AP MLD transmitting the beacon frame is NSTR AP MLD or not NSTR AP MLD according to the set value (e.g., if set to "0", it may indicate not NSTR AP MLD; if set to "1", it may indicate NSTR AP MLD).
As such, the application method of the subfield indicating whether or not is NSTR AP MLD may be used as a method of explicitly indicating whether or not the AP MLD is NSTR AP MLD.
As another example, NSTR AP MLD can implicitly indicate itself as NSTR AP MLD, rather than directly indicating itself as NSTR AP MLD via a particular subfield. Specifically, NSTR AP MLD indicates that it has an NSTR link pair while indicating that it has two supportable links, thereby implicitly indicating that it is NSTR AP MLD. In this case, NSTR AP MLD can set the maximum simultaneous link number subfield (Maximum Number Of Simultaneous Links subfield) included in the beacon frame to 1 (or a predetermined value representing 2) to indicate that it can support two links. In this case, NSTR AP MLD can set the NSTR link pair present subfield included in the beacon frame to 1 or 0 to indicate that it has an NSTR link pair.
The AP MLD may transmit a beacon frame by using the above method, thereby informing the non-AP STA MLD of NSTR AP MLD in an explicit method or an implicit method. The non-AP STA MLD may implicitly or explicitly recognize whether the AP MLD transmitting the beacon frame is NSTR AP MLD through the received beacon frame. If the AP MLD transmitting the beacon frame is NSTR AP MLD (i.e., the AP MLD is NSTR AP MLD indicated by the beacon frame by an explicit or implicit method), the non-AP STA MLD may perform a procedure of Association (Association) or Setup (Setup) with NSTR AP MLD only through a link receiving the beacon frame. That is, the non-AP STA MLD may transmit and receive frames for association or setting with NSTR AP MLD through a link (e.g., a main link) that receives the beacon frames. For example, the transmission and reception of frames for association or setting with APs connected through links other than the main link included in NSTR AP MLD may be performed only through the main link. In this case, the (ML) (Re) association request frame (association request frame) transmitted by the non-AP STA MLD may be transmitted by a link other than the main link (non-main link).
In this case, NSTR AP MLD may not indicate information about the non-primary link AP in the RNR element of the beacon frame (transmitted on the primary link) to prevent the non-AP STA MLD from attempting a setup procedure through the non-primary link. That is, the beacon frame sent by the AP of NSTR AP MLD may not include/indicate the neighbor AP information fields of the APs (of the same MLD) on other links. In this case, the non-AP STA MLD may not confirm information about the AP of the non-main link after receiving the beacon frame, and thus may not attempt setting for NSTR AP MLD on the non-main link. In this case, the non-AP STA MLD that receives the beacon frame that does not include the neighbor AP information field for the AP of the non-main link from NSTR AP MLD may implicitly recognize that the counterpart AP is NSTR AP MLD based on the fact that the number of links simultaneously supported by the AP transmitting the beacon frame is two (as described above) and information about another AP in the same MLD is not indicated.
In addition, when the normal AP MLD receives the (ML) (Re) association request frame (Association Request frame) from the STA (MLD), it is necessary to transmit the (ML) association response frame (Association Response frame) through a link that receives the (ML) association request frame. However, NSTR AP MLD may be allowed to perform a response to a (ML) association request frame received over a non-main link (i.e., may respond to a (ML) association response frame over a main link) over a main link.
As described above, this may be allowed because NSTR AP MLD is somewhat limited in the operation of transmitting through non-main links as compared to normal APs. More specifically, in the case of NSTR AP MLD, there is an operational limitation in that when a response to a (ML) association response frame is transmitted through a non-main link, transmission must be started together in the main link. This may be an operational limitation that is considered to prevent the BLIND (BLIND) state of the AP of the main link, as considered in other embodiments of the present invention.
Thus, when NSTR AP MLD receives (ML) (Re) association request frames over a non-primary link, response frames may be associated by primary link response (ML) (Re) or may be associated by both primary link and non-primary link. That is, STA MLD transmitting (ML) (Re) association request frame through non-main link of NSTR AP MLD may wait for receiving (ML) (Re) association response frame in main link after knowing that the response to itself transmitted request frame will be responded through main link.
The RNR element transmitted by the AP through the beacon frame may include a specific TBTT information field including an MLD parameter field. In this case, if the MLD ID in the MLD parameter field is set to "0", the STA MLD may recognize that an AP corresponding to the neighbor AP information field including the MLD parameter field is included in the AP MLD including the AP transmitting the beacon frame. That is, the STA MLD may recognize that the corresponding neighbor AP information field indicates information about another AP included in the same AP MLD as the AP transmitting the beacon frame. In this case, the method by which the STA MLD interprets/acquires it may be the same as/similar to the operation performed by the legacy STA after receiving the RNR element.
However, in the case of the NSTR soft AP, since the beacon frame is not transmitted in the non-main link, information related to the beacon frame of another AP (the AP of the non-main link) may not be indicated by the RNR element. More specifically, since the NSTR soft AP MLD does not transmit the beacon frame through the AP of the non-main link, when the basic information of the AP of the non-main link is indicated in the RNR element, information about the beacon frame cannot be indicated. For example, the non-primary link that does not transmit a beacon frame does not have information corresponding to the TBTT information count (Information Count), TBTT information length, neighbor AP TBTT offset subfield that needs to be indicated by the RNR element. Thus, the NSTR soft AP MLD may need to set the TBTT-related field in the neighbor AP information field corresponding to the AP that is not the main link to a preset value when transmitting the RNR element through the AP on the main link.
The neighbor AP TBTT offset subfield of the TBTT information field (see (b) of fig. 11) is a subfield for indicating information about the next TBTT of another AP to be indicated. That is, the neighbor AP TBTT offset subfield included in the neighbor AP information field may include information about the next TBTT of the AP corresponding to the neighbor AP information field. For example, if the AP1 that is transmitting the beacon frame indicates information about the AP2 through the RNR element (through the neighbor AP information field), the neighbor AP TBTT offset subfield corresponding to the AP2 indicates how much TU (time unit, 1024 us) difference exists in the next TBTT of the AP2 compared to the last TBTT of the AP 1. In this case, the value indicated by the neighbor AP TBTT offset subfield is a value that rounds down the TBTT offset to a neighbor integer. That is, if an AP indicates a value of 10 in a neighbor AP TBTT offset subfield of another AP, a next TBTT of the other AP may be different from a previous TBTT of the AP by a time interval of more than 10 TUs to less than 11 TUs.
However, when the main link AP in the NSTR softap MLD sets the neighbor AP TBTT offset subfield (1-octet) corresponding to the non-main link AP, it may need to be set to a preset value (e.g., 254 or 255). This may be because the NSTR soft AP does not transmit a beacon frame on the non-main link, and thus cannot determine the target beacon transmission time (Target Beacon Transmission Time, TBTT) as a predetermined point in time to transmit the next beacon frame. That is, the beacon frame transmitted by the NSTR soft AP MLD over the main link may require that neighbor AP TBTT offset subfields corresponding to APs that are not main link be set to 254 and/or 255 by the RNR element. In this case, the neighbor AP TBTT offset subfield corresponding to the non-primary link may exist in the TBTT information field including the MLD parameter field in which the MLD ID subfield is set to 0.
Thus, after receiving the beacon frame from the NSTR soft AP MLD, if the non-AP STA MLD confirms the TBTT information field in which the MLD ID subfield is 0 and the TBTT offset subfield is indicated as 254 and/or 255 in the specific neighbor AP information field in the RNR element included in the beacon frame, it can be recognized that the specific neighbor AP information field may be information about an AP operating in the non-main link of the NSTR soft AP MLD (AP of the NSTR soft AP MLD). As such, when the non-AP STA MLD receiving the beacon frame from the NSTR soft AP MLD confirms the information about the AP MLD operated by the non-main link of the corresponding NSTR AP MLD, the probe request frame and the ML probe request frame should not be transmitted to the above-described NSTR soft AP MLD through the non-main link.
Further, when the non-AP STA MLD knows that the received beacon frame is a beacon frame transmitted by the MLD, and a neighbor AP TBTT offset subfield corresponding to another AP in the same MLD as the AP transmitting the beacon frame (reporting AP) is indicated as 254 and/or 255, the non-AP STA MLD should not transmit a probe request frame and an ML probe request frame to the other AP.
Further, when the non-AP STA MLD knows that the received beacon frame is a beacon frame transmitted by the MLD, and a neighbor AP TBTT offset subfield corresponding to another AP to which the AP (reporting AP) transmitting the beacon frame is in the same MLD is indicated as 254 and/or 255, the non-AP STA MLD should not transmit a probe request frame and an ML probe request frame to the other AP.
< MLD AP TBTT offset indication >.
In some embodiments of the foregoing invention, it is mentioned that the beacon frame sent by the NSTR soft AP MLD may indicate the neighbor AP TBTT offset subfield corresponding to the AP that is not the main link as a preset value (254 and/or 255). However, even if not corresponding to an AP of the non-main link of the NSTR softap MLD, the neighbor AP TBTT offset subfield may be indicated as 254 or 255. For example, if the TBTT offset of another AP, which is known by the AP transmitting the beacon frame, is 254 TUs or more (254 TUs or more), the AP may indicate a neighbor AP TBTT offset subfield corresponding to the other AP in the beacon frame as 254. In addition, if the AP transmitting the beacon frame cannot accurately know the TBTT offset of another AP, the AP may indicate the neighbor AP TBTT offset subfield corresponding to the other access point as 255.
However, an AP in the MLD should not indicate (set) a neighbor AP TBTT Offset subfield corresponding to another AP (in the same MLD) to 255 when indicating (setting) the neighbor AP TBTT Offset subfield by the RNR element, because it can always know the TBTT Offset of another AP in the MLD.
In particular, the neighbor AP information field included in the RNR element of the beacon frame may include a neighbor AP TBTT offset subfield indicating an offset between times at which the beacon frame is transmitted. In this case, the neighbor AP TBTT offset subfield indicates an offset value between a point of time when a beacon frame is transmitted and a point of time when a next beacon frame of an AP corresponding to the neighbor AP TBTT offset subfield among the plurality of APs included in the AP MLD (NSTR or STR AP MLD) is transmitted. In this case, the neighbor AP TBTT offset subfield may not be set to a specific value according to a specific condition.
For example, if included in the same AP MLD as the AP transmitting the beacon frame, the neighbor AP TBTT offset subfield may not be set to a specific value (e.g., "255"). At this time, the size of the neighbor AP TBTT offset subfield may be 8 bits, and in this case, the neighbor AP TBTT offset subfield may not be set to the maximum value that the neighbor AP TBTT offset subfield can indicate (because in the case of 8 bits, the maximum offset value that can be represented by 8 bits may be 255, corresponding to values of 0 to 255, respectively). However, if not included in the same AP MLD as the AP transmitting the beacon frame (e.g., in the case where the AP is a legacy AP, etc.), the neighbor AP TBTT offset subfield may be set to a specific value (e.g., "255").
In a similar embodiment, the neighbor AP TBTT offset subfield may be interpreted as a different value depending on the particular conditions.
For example, if the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), it may be interpreted differently as "254" or greater than "254" depending on the specific condition.
Specifically, if an AP corresponding to a neighbor AP information field including a neighbor AP TBTT offset subfield is included in the same AP MLD as an AP transmitting a beacon frame or a different MLD, and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs. However, if not included in the same AP MLD as the AP transmitting the beacon frame or a different MLD (e.g., in the case where the AP is a legacy AP, or an AP not included in the MLD, etc.), and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs or more TUs.
In general, the reason that the legacy AP transmits the TBTT offset information together with the basic information of the neighbor AP in the beacon frame may be that an STA that helps to receive the beacon frame quickly obtains the basic information of other APs and receives the beacon frame from other APs more efficiently using the determined TBTT offset information.
However, the neighbor AP TBTT offset subfield included in the legacy beacon frame is composed of 1 octet, which is designed to be able to indicate only the TBTT offset corresponding to 254 TUs at maximum. Considering the maximum TBTT offset that another AP may have (either (2-16) or (2-16) -1 TU when considering the configurable beacon interval), the design of the neighbor AP TBTT offset subfield may compromise the form of beacon frame overhead and information that can be indicated by excluding support for information for TBTT offsets greater than 254 TUs or more.
However, when the AP MLD indicates information about another AP within the MLD through the beacon frame, an additional MLD AP TBTT offset subfield may be included to transmit in order to more accurately inform the TBTT offset of the other AP. When an AP MLD transmits a beacon frame, an MLD AP TBTT offset subfield may be included in a TBTT information field corresponding to another AP present in the same MLD. In this case, if the neighbor AP TBTT offset subfield and the MLD AP TBTT offset subfield are indicated together in a specific TBTT information field, the neighbor AP TBTT offset subfield may be indicated with a preset value (may be 254 or 255). The MLD AP TBTT offset subfield is a 2 octet subfield that can be used to indicate a TBTT offset value when the TBTT offset between an AP transmitting a beacon frame (reporting AP) and another AP in the same MLD (reported AP) exceeds 254 TUs. More specifically, when the AP MLD transmits a beacon frame, when the TBTT offset of another AP in the same MLD exceeds 254 TUs and cannot indicate an accurate TBTT offset with the existing neighbor AP TBTT offset subfield, the MLD AP TBTT offset subfield may be restrictively included in the TBTT information field.
If the STA MLD confirms the TBTT information field including the MLD AP TBTT offset subfield in the RNR element included in the beacon frame received from the specific AP, the TBTT offset of the AP corresponding to the TBTT information field may be confirmed based on the value indicated in the MLD AP TBTT offset subfield. In this case, in order to determine whether the TBTT information field included in the beacon frame includes the MLD AP TBTT offset subfield, the STA may determine from the value of the TBTT information length subfield (in the TBTT information header (subfield) of each neighbor AP information field) corresponding to each TBTT information field. That is, if the STA recognizes that the TBTT information field includes the MLD AP TBTT offset subfield according to the value of the TBTT information length subfield, the TBTT offset of the AP corresponding to the TBTT information field may be determined according to the value indicated in the MLD AP TBTT offset subfield. In this case, if the value indicated by the MLD AP TBTT offset subfield of the specific TBTT information field is 0 or a preset value (or 254 or less), the STA MLD may determine the TBTT offset of the AP corresponding to the above specific TBTT information field based on the value of the neighbor AP TBTT offset subfield.
Fig. 12 illustrates another example of a TBTT information field format according to an embodiment of the present invention.
Referring to fig. 12, the TBTT information field may have a configuration including an MLD AP TBTT offset subfield. The MLD AP TBTT offset subfield may be included only in the beacon frame transmitted by the AP of the AP MLD. Further, the MLD AP TBTT offset subfield may be included only in a TBTT information field corresponding to another AP of the same MLD as the AP transmitting the beacon frame.
For example, in a beacon frame transmitted by a specific AP of an AP MLD, in order to indicate that the TBTT offset of another AP of the same MLD is 300 TUs, a TBTT information field corresponding to the other AP may be used in a format including an MLD AP TBTT offset subfield. In this case, the neighbor AP TBTT offset subfield of the TBTT information field corresponding to the above-described other AP may be indicated as 254 or 255, and the MLD AP TBTT offset subfield may be indicated as a value corresponding to 300 TUs (e.g., 300 or 299, or (300-254)). In this case, the above-described MLD AP TBTT offset subfield is an exemplary subfield name, and subfields for the same purpose may be defined with different names.
Fig. 13 illustrates one example of a TBTT information length subfield (Information Length subfield) indicating a TBTT information field including an MLD AP TBTT Offset subfield (Offset subfield) according to an embodiment of the present invention.
Referring to fig. 13, the type of content included in the TBTT information field may be indicated according to the TBTT information length subfield. The TBTT information length subfield may be a subfield included in a TBTT information header field existing in a neighbor AP information field included in the RNR element. That is, the RNR element transmitted through the beacon frame may include a plurality of neighbor AP information fields, and the TBTT information field included in each neighbor AP information field may be a structure including different amounts and types of contents. In this case, since the TBTT information field included in each neighbor AP information field may include different amounts and types of contents, the contents (and format) information indicated by each TBTT information field is indicated by the TBTT information header field.
That is, the STA may interpret each neighbor AP information field in the RNR element of the beacon frame received through the AP according to the information indicated in the TBTT information header. In this case, each of the interpreted neighbor AP information fields may indicate information about a neighbor AP or another AP in the same MLD. In this case, if the value of the TBTT information length subfield included in the TBTT information header field means a content configuration including the MLD AP TBTT offset subfield, as shown in fig. 13, the STA may determine the TBTT offset of the AP corresponding to the corresponding TBTT information field according to the value indicated in the MLD AP TBTT offset subfield.
As another approach, the AP MLD may be limited in that it should manage the TBTT offset between APs it operates such that it does not exceed 254 TUs or 255 TUs.
In this case, the AP MLD may need to adjust the beacon interval of the AP it operates on each link and/or the TBTT time point (setting) of the BSS that each AP operates to ensure that the TBTT time point difference between the APs attached to the MLD does not exceed 254 TUs or 255 TUs. In this case, the above beacon interval, TBTT time point adjustment, and the like are all examples of methods for changing the TBTT interval of each AP in the MLD, and other implementations for adjusting the TBTT offset so that a specific time value (254 TUs or 255 TUs) is not exceeded may also be applied. Further, the method by which the AP MLD ensures that the TBTT time points of the respective APs in which it operates do not differ by more than a specific interval (254 TUs or 255 TUs) may not be separately defined.
Thus, if an AP MLD adjusts the TBTT time point difference of each AP it operates to be 254 TUs or less or 255 TUs, a neighbor AP TBTT offset subfield value transmitted for another AP in the same MLD in an RNR element of a beacon transmission of a specific AP may be indicated by only 253 or 254 or less. More specifically, if a specific AP MLD manages the TBTT time point difference of an AP to which it operates as 254 or less than 255 TUs, a subfield corresponding to another AP affiliated to the same AP MLD (the above specific AP MLD) among neighbor AP TBTT offset subfields transmitted by the specific AP affiliated to the above specific AP MLD may indicate (have) only a value of 254 or less.
As described above, if the AP MLD maintains the TBTT time point difference of each AP in which it operates to be 254 TUs or less or 255 TUs, the non-AP STA may need to interpret neighbor AP TBTT offset subfields of beacon frames received from the APs of the above AP MLD in another method than the above interpretation method. In this case, the above-described interpretation method may refer to an interpretation method when the value of the neighbor AP TBTT offset subfield indicates 254. That is, the above-described interpretation method may be to interpret a time interval between a last TBTT of the reporting AP and a next TBTT of the reported AP (transmitted after the above-described last TBTT) as 254 TUs or more when the value of the neighbor AP TBTT offset subfield indicates 254. In this case, another interpretation method described above is to interpret the time interval between the last TBTT of the reporting AP and the next TBTT of the reported AP (transmitted after the last TBTT) as more than 254 TUs and less than 255 TUs when the value of the neighbor AP TBTT offset subfield indicates 254. Alternatively, another interpretation method described above is to interpret the time interval between the last TBTT of the reporting AP and the next TBTT of the reported AP (sent after the last TBTT) as 254 TUs when the value of the neighbor AP TBTT offset subfield indicates 254.
Since the time point difference between TBTTs of the respective APs operated by the AP MLD has been adjusted to 254 TUs or less or 255 TUs by the AP MLD, this may be an explanation method reflecting the operation characteristics of the AP MLD while the existing neighbor AP TBTT offset subfield has the meaning of "254 TUs or more".
That is, when a non-AP STA receives a neighbor AP TBTT offset subfield for another AP of an AP MLD through a beacon received from a specific AP of the AP MLD, if the value of the subfield is 254, it may be interpreted that the TBTT offset of the other AP is 254 TUs or (more than 254 TUs, less than 255 TUs).
In other words, if a non-AP STA included in the non-AP STA MLD receives a neighbor AP TBTT offset subfield for another AP through a beacon received from a specific AP of the AP MLD, the value indicated by the neighbor AP TBTT offset subfield may be interpreted differently according to a specific case.
That is, if the neighbor AP TBTT offset subfield included in the beacon frame is set to a specific value (e.g., "254"), the non-AP STA receiving the beacon frame may interpret the specific value as the specific value itself according to a specific condition or may interpret it as a value indicating higher than the specific value. For example, if an AP corresponding to a neighbor AP information field including a neighbor AP TBTT offset subfield is included in the same AP MLD as an AP transmitting a beacon frame or in a different MLD, and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs. However, if not included in the same AP MLD as the AP transmitting the beacon frame or in a different MLD (e.g., the AP is a legacy AP, an AP not included in the MLD, etc.), and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs or more.
In addition, even in the case of receiving a beacon frame from an AP of an AP MLD, if a neighbor AP TBTT offset subfield other than an AP for the same AP MLD among neighbor AP TBTT offset subfields included in the beacon frame indicates 254, that is, a neighbor AP TBTT offset subfield for a legacy AP as well as an AP other than the MLD indicates 254, the non-AP STA should interpret that it indicates a TBTT offset of 254 TUs or more.
In this case, the method by which the non-AP MLD distinguishes whether a particular neighbor AP TBTT offset subfield is for another AP of the same AP MLD may be based on information of an MLD parameter subfield included in the same TBTT information field as the above-described particular neighbor AP TBTT offset subfield. More specifically, when the MLD ID subfield value of the MLD parameter subfield included in the same TBTT information field as the specific neighbor AP TBTT offset subfield is 0, the non-AP STA may interpret the above specific neighbor AP TBTT offset subfield as an AP in the same MLD as the AP transmitting the beacon frame.
That is, when the neighbor AP TBTT offset subfield of the TBTT information field in which the MLD ID subfield value is 0 is indicated as 254, the non-AP STA may interpret the above-described neighbor AP TBTT offset subfield as a TBTT offset indicating more than 254 TUs to less than 255 TUs. In this case, the non-AP may further consider whether the beacon frame includes an ML element (whether the AP transmitting the beacon frame is an MLD) to interpret the neighbor AP TBTT offset subfield.
That is, when the neighbor AP TBTT offset subfield of the TBTT information field in which the MLD ID subfield value is not 0 (e.g., in the case of 1 to 255) is indicated as 254, the non-AP STA may interpret the above-described neighbor AP TBTT offset subfield as indicating a TBTT offset of 254 TUs or more.
< non-primary link setup and management >.
As described above, NSTR AP MLD cannot transmit beacon frames, probe response frames, and Multi-link (ML) probe response frames over non-main links. Therefore, the STA MLD desiring to connect with NSTR AP MLD should transmit a (ML) probe request frame only through a link in which NSTR AP MLD transmits a beacon frame.
The ML probe request frame transmitted by the STA of the EHT non-AP STA MLD may have a configuration including EHT capability information and a multilink element in addition to information included in the probe request frame transmitted by the legacy HE STA. In this case, the multilink element included in the ML probe request frame may allow the MLD transmitting the ML probe request frame to request additional information of the AP on other links from the AP MLD.
For example, the non-AP STA MLD may request the AP MLD to attach complete or partial information about APs on other links through a multi-link element of the ML probe request frame when transmitting the ML probe request frame. That is, the AP MLD may be requested to transmit all or part of parameters related to a link of another AP included in the same AP MLD to the AP receiving the ML probe request frame.
For example, when all or part of parameters related to an AP connected through a non-main link are updated, stations included in the non-AP STA MLD may request that the AP connected through the main link transmit all or part of updated parameters related to another AP connected through the non-main link.
In this case, requesting/responding to complete information means requesting/responding to the same level of information as the AP (reporting AP) responding to the ML probe response frame for the AP (reporting AP) on the other link. In this case, the request/response part information means that, among information about APs on other links, only the information requested by the STA is responded.
If additional information about APs on other links is requested in an ML probe request frame received through a specific link, an AP MLD transmitting a beacon frame may respond with an ML probe response frame, providing not only information about APs on the specific link but also additional information about APs on the other links being requested.
In this case, if the STA MLD transmits an ML probe request frame on a specific link and requests complete information about APs on other links, the AP MLD may need to provide information about APs on the other links at the same level as the information about APs on the specific link through an ML probe response frame responded on the specific link. In other words, for the APs on the other links, the STA MLD that receives the response to the complete information of the APs on the other links through the specific link may obtain the same level of information as if the ML probe response was received directly from the APs on the other links.
In this case, if the STA MLD transmits an ML probe request frame on a specific link and requests partial information about APs on other links, the AP MLD may provide only the requested information about APs on other links (information of requested elements) through an ML probe response frame responded on the specific link. In other words, the STA MLD that receives the response of the partial information about the AP on the other link through the specific link may additionally acquire only the information requested by itself about the AP on the other link. In this case, the STA MLD requesting partial information about the AP on the other link may transmit an ML probe request frame including a link ID corresponding to the other link and information (which may be represented by a requested element ID field) indicating additional information that it desires to acquire. Accordingly, if the ML probe request frame received through a specific link includes information (requested element ID field) indicating information about other links, the AP MLD may additionally indicate information about the other links indicated above through the ML probe response frame.
In this case, when transmitting the ML probe request frame through a specific link, the STA MLD may set a complete profile subfield corresponding to other links (in each STA control field (Per-STA Control field) included in the multi-link element) to 0 or 1 to indicate whether to request complete information or partial information of the other links.
In this case, additional information (full and partial) about another AP may be transmitted through each STA Profile (Per-STA Profile) included in the multilink element of the ML probe response frame. Each STA profile is a field of 0 or more than 0 included in the multi-link element, and may include information of other STAs (AP and non-AP STAs) present in the same MLD as the STA (AP and non-AP STA) transmitting the frame including the multi-link element. In this case, each STA profile has a configuration including a complete profile subfield, and complete information (the same level of information as that of STAs (AP and non-AP) transmitting frames including a multilink element) of other STAs (AP and non-AP STAs) corresponding (corresponding) to each STA profile in which the complete profile subfield indicates 1 can be obtained through the corresponding each STA profile. However, parameters/elements representing the same level of information as STA (AP and non-AP) information transmitting the respective STA profiles may be omitted by following inheritance (inheritance) rules. The inheritance rule may mean that, in order to prevent duplicate indications of the same parameters and elements, inheritance applies values of the same parameters and elements (indicated for other STAs (AP and non-AP)) that have been indicated when the corresponding parameters and elements are not indicated. That is, if the value of parameter 1 is indicated for STA1 and the value of parameter 1 is not indicated for STA2, it may be interpreted that the value of parameter 1 for STA2 is the same as the value of parameter 1 for STA1 according to the inheritance rule.
In this case, each STA profile sub-element (Profile subelement) included in the multi-link element transmitted by NSTR AP MLD may have a Beacon Interval (Beacon Interval) sub-field that does not include an Interval for indicating that a Beacon is transmitted. That is, NSTR AP MLD may require that the beacon interval present (Beacon Interval Present) subfield be set to 0 when each STA profile subelement corresponding to an AP that is not a main link is indicated in the multi-link element. This may be because the AP in NSTR AP MLD operating on a non-main link does not transmit a beacon frame and therefore there is no separate beacon frame period. That is, even if the complete profile subfield (in each STA control field) is indicated as 1, the beacon interval present subfield of each STA profile subelement (in probe response and association response frames) corresponding to the AP of the non-primary link in NSTR AP MLD may be indicated as 0. That is, even in the case where the complete information is indicated, the beacon interval information of the AP of the non-main link does not exist.
Likewise, DTIM information (DTIM count and DTIM period information) regarding APs that are not primary links may not exist even in the case where the integrity information is indicated. That is, even if the complete profile subfield (in each STA control field) is indicated as 1, the DTIM information present (DTIM Info Present) subfield of each STA profile corresponding to the AP of the non-main link in NSTR AP MLD may be indicated as 0.
That is, since the beacon is not transmitted through the non-main link, even in the case where the non-AP STA MLD requests all information (or all update information) about another AP on the non-main link through the AP on the main link of the AP MLD (i.e., the case where the complete information is set to "1"), the beacon interval and DTIM information about the AP on the non-main link may not exist in the ML probe response frame. That is, each STA profile subelement for APs that are not primary links included in the ML probe response frame may not include beacon interval and DTIM information.
In this case, even though all information (or all update information) about another AP that is not the main link has been requested, the AP MLD may not include beacon interval and DTIM information about the AP that is not the main link in the ML probe response frame. Accordingly, in this case, the AP MLD may transmit by setting the beacon interval present subfield and the DTIM information present subfield to values (e.g., "0") indicating that the corresponding fields do not exist, respectively.
With NSTR AP MLD, since the beacon frame is not transmitted on the non-main link, DTIM information and beacon interval information may not be indicated when information about the AP of the non-main link is indicated. That is, NSTR AP MLD may require that the DTIM information present subfield in each STA profile (more precisely, STA control field) corresponding to the AP of the non-main link be always set to 0. That is, NSTR AP MLD may require that the beacon interval present subfield in each STA profile corresponding to the AP of the non-main link be always set to 0. Accordingly, even in the case where NSTR AP MLD receives an ML probe request frame or (ML) (Re) association request frame requesting complete information from the non-AP STA MLD, NSTR AP MLD may still need to set the beacon interval present subfield and the DTIM information present subfield in each STA profile corresponding to the AP of the non-main link to 0 at all times.
Alternatively, since the beacon frame is not transmitted in the non-main link, NSTR AP MLD may need to set the beacon interval, DTIM count, and DTIM interval subfield in each STA profile corresponding to the AP of the non-main link to predetermined values. This may be considered as an operation considered to maintain the same STA profile structure as a normal AP MLD (e.g., STR AP MLD) when NSTR AP MLD transmits (responds to) complete information about APs that are not main link. That is, the STA MLD may request complete information about a specific link from the AP MLD using an ML probe request frame or the like, and then expect a response to get complete information about an AP on the specific link in a response frame. In this case, if the complete information responded to by NSTR AP MLD has a different STA profile structure from that of the STR AP MLD, the implementation complexity of the procedure of the STA MLD to acquire information through the STA profiles may increase. Thus, in responding to the integrity information of the non-primary link, NSTR AP MLD may use STA profiles of the same structure as STA profiles used when the normal AP MLD responds to the integrity information even though the AP of the non-primary link does not transmit a beacon frame. In this case, the beacon interval subfield, the DTIM count subfield, and the DTIM interval subfield of each STA profile corresponding to the AP of the non-main link of NSTR AP MLD may be set to preset values, respectively. For example, in transmitting complete information about APs that are not primary links, NSTR AP MLD can set individual bits in the beacon interval subfield of the non-primary links to all 0, all 1, or a pre-agreed value. For example, in transmitting complete information about the non-main link APs, NSTR AP MLD can set the individual bits in the DTIM count subfield of the non-main link to all 0 s, all 1 s, or a pre-agreed value. For example, in transmitting complete information about the non-main link APs, NSTR AP MLD can set the individual bits in the DTIM interval subfield of the non-main link to all 0 s, all 1 s, or a pre-agreed value.
Alternatively, since the beacon frame is not transmitted on the non-main link, NSTR AP MLD can set the beacon interval, DTIM count, and DTIM interval subfield in each STA profile corresponding to the AP of the non-main link to values related to the beacon frame of the main link, which can be an operation considered to maintain the same each STA profile structure, as described above. In this case, the beacon interval subfield and the DTIM count subfield and the DTIM interval subfield in each STA profile corresponding to the AP of the non-main link in NSTR AP MLD may be set to values related to the beacon frame transmitted on the main link, respectively. For example, when transmitting complete information about an AP that is not a primary link, NSTR AP MLD can set the beacon interval subfield of the non-primary link to a value indicating (representing) the beacon interval of the primary link. For example, when transmitting complete information about APs that are not primary links, NSTR AP MLD can set the DTIM count subfield of the non-primary links to the DTIM count value of the primary links. For example, when transmitting complete information about an AP that is not a primary link, NSTR AP MLD can set the DTIM interval subfield of the non-primary link to a value indicating (representing) the DTIM interval of the primary link.
Alternatively, since the beacon frame is not transmitted in the non-main link, NSTR AP MLD can set the beacon interval, DTIM count, and DTIM interval subfield of each STA profile corresponding to the AP of the non-main link to values having a specific purpose. More specifically, the beacon interval subfield of the non-main link may be set by the AP MLD to a value (dummy beacon interval) having a specific purpose, for example, a value for calculation. The beacon interval in the conventional Wi-Fi refers to a value related to a time interval (interval) in which a beacon frame is transmitted as shown in the word, but is also used as a time unit (time units) for various BSS operations. For example, units of a join failure timeout (JointFailureTimeout), a query failure timeout (query failure timeout) primitive, and the like are defined in beacon intervals, and a listening interval field, a PRAW start offset subfield, an AID request interval field, an AID switch timing field, an AID response interval field, a minimum transmission interval subfield, a channel quality measurement duration, a color switch countdown (in BSS color change announcement element) subfield, and the like are indicated using a beacon interval (or TBTT) as a basic unit. As such, since the beacon interval has a meaning of a value related to an interval at which an actual beacon frame is transmitted, and is also a value used as a unit of various primitives and fields, it may be necessary to define (instruct, set) the beacon interval for the non-main link even if the beacon frame is not actually transmitted in the non-main link so as to be used as a unit of the above-described primitives/subfields.
That is, even if a beacon frame is not transmitted on the non-main link, the NSTR AP MLD can indicate the beacon interval subfield of each STA profile corresponding to the AP of the non-main link as a beacon interval value to be used as a time unit of the non-main link. In this case, the non-AP MLD may identify (determine, calculate) the duration and interval of the above-described primitives and fields (in beacon intervals as time units) based on the values indicated in the beacon interval subfield of each STA profile corresponding to the AP of the non-main link. At this time, the DTIM interval subfield and the DTIM count subfield of each STA configuration file corresponding to the AP of the non-main link may also be set according to the BSS operation purpose of the AP MLD, and the non-AP MLD operating the STA in the non-main link may need to operate according to the set values when operating the STA in the non-main link.
In addition, the above method of setting the subfields (beacon interval, DTIM count, DTIM interval, etc.) related to the beacons of the non-main link of NSTR AP MLD may be applied not only to each STA profile transmitted on the main link, but also to other frames and subfields (transmitted on the main link or the non-main link) including information related to the beacons of the non-main link.
Further, the non-AP STA MLD, which is expected to be associated with NSTR AP MLD, may need to use a unit of a listening interval field transmitted when requesting the setting of the primary link and the non-primary link as a beacon interval of the primary link of NSTR AP MLD. In other words, the non-AP STA MLD transmitting the listening interval field to NSTR AP MLD should calculate and set the unit of the listening interval field to NSTR AP MLD the beacon interval of the AP operating on the main link. In this case, the listening interval field may be a field indicating information about a period (time) in which the non-AP STA MLD performing the multi-link (re) association switches at least one STA to the awake state to receive the beacon frame. In this case, the listening interval field may indicate a value derived when the listening interval parameter is indicated in the MLME primitive.
In this case, when the non-AP STA MLD transmits the listening interval field to an AP MLD (e.g., STR AP MLD) other than NSTR AP MLD, the unit of the listening interval field may be set to the maximum value among the beacon intervals of the link (AP on) it wishes to perform the setting. For example, when the non-AP STA MLD is to perform multi-link setting with the link 1 and the link 2, the non-AP STA MLD may use a larger value of the beacon interval of (the AP on) the link 1 and the beacon interval of the link 2 as a unit of the listening interval field included in the ML association request frame. That is, if the beacon interval of link 1 is 100ms and the beacon interval of link 2 is 50ms, the unit of the listening interval subfield transmitted by the non-AP STA MLD may be 100ms.
In general, if the AP and STA have completed the setup, the STA may receive the beacon frame transmitted by the AP and identify and track (update) the operating parameters and element change contents of the AP. In addition, the beacon frame may include a time stamp field to provide information for time synchronization by STAs within the BSS.
However, in the case of NSTR AP MLD, since the beacon frame is not transmitted on the non-primary link, the STA MLD performing the setup with NSTR AP MLD may need to perform additional operations to track (update) parameters/elements with respect to the non-primary link and maintain time synchronization.
According to an embodiment of the present invention, the non-AP STA MLD associated with NSTR AP MLD may, after receiving the beacon frame at the primary link, acknowledge the non-primary link's change sequence (in the RNR element's MLD parameter field) and send an ML probe request. In this case, the ML probe request frame transmitted by the non-AP STA MLD may be transmitted in order to request the changed parameters and element information of the non-main link. In this case, the complete profile of each STA profile corresponding to the non-primary link (and the AP of the non-primary link) may be set to 1 when the ML probe request frame is transmitted, thereby requesting complete information of the non-primary link. Alternatively, the ML probe request frame transmitted by the STA MLD for updating parameters/elements of the non-primary link may request update information instead of complete/partial information of the non-primary link.
In other words, even in the case where a plurality of links are formed between the non-AP STA MLD and the AP MLD, the frame for performing the association, re-association, and/or update parameter procedures may be performed only through the main link. For example, through a specific field (e.g., a change sequence or BSS parameter change count subfield) included in neighbor AP information included in a beacon frame, indicating whether parameters of a link with respect to another AP have been updated, the STA recognizes that parameters with respect to an AP other than the main link have been updated, and the non-AP STA MLD may request transmission of the updated parameters through the main link other than the non-main link of the other AP. That is, the non-AP MLD cannot transmit a frame (e.g., a probe request frame, etc.) for requesting updated parameters through the non-main link.
For example, after performing the setting with NSTR AP MLD, the non-AP STA MLD requesting information for updating parameters/elements of the non-main link may request changed parameters/elements with respect to the AP of the non-main link by setting an updated profile subfield of each STA profile corresponding to the non-main link to 1 in an ML probe request frame transmitted through the main link. If the updated profile subfield indication in each STA profile (corresponding to the non-primary link) of the received ML probe request frame is 1, NSTR AP MLD may respond with an ML probe response frame that includes changed information (parameters and elements) of the non-primary link.
In this case, each STA profile field in the ML probe request frame transmitted by the non-AP STA MLD may have a configuration including an updated profile subfield and a recorded change sequence subfield. The recorded change sequence subfield indicates the latest change sequence value maintained by the non-AP STA MLD for the non-primary link, and the AP MLD may confirm/determine the type of update information according to the value indicated by the recorded change sequence subfield.
For example, NSTR AP MLD can change parameter 1 by increasing the change sequence number of the non-main link from 100 to 101, and then change parameter 2 by increasing the change sequence number from 101 to 102. At this time, the STA MLD may transmit an ML probe request frame and request update information of the non-primary link. In this case, if the non-AP STA MLD indicates the recorded change sequence subfield as 100, NSTR AP MLD may respond with an ML probe response frame including parameters 1 and 2, and if the non-AP STA MLD indicates the recorded change sequence subfield as 101, NSTR AP MLD may respond with an ML probe response frame including only parameters 2.
In this case, the non-AP STA MLD may not request an updated profile using a separate updated profile subfield, but indicate a complete profile subfield as 0. In other words, the method of the non-AP STA MLD requesting the updated profile may be to set the complete profile subfield to 0, in which case a separate updated profile subfield may not be included in each STA profile.
Fig. 14 illustrates a format of each STA profile subelement (Per-STA Profile subelement) of each STA according to an embodiment of the present invention.
Referring to fig. 14 (a), each STA profile subelement may have a configuration including a STA control field. The STA control field (see (b) of fig. 14) represents information indicating the type of a field included in the STA profile (see (a) of fig. 14) of the corresponding STA profile subelement. At this time, in the specific individual STA profile sub-elements transmitted by other AP MLDs except NSTR AP MLD, if the complete profile sub-field in the STA control field indicates 1, the MAC address presence sub-field, the beacon interval presence sub-field, and the DTIM information presence sub-field should all be indicated as 1. However, as described above, since NSTR AP MLD does not transmit a beacon frame on the non-primary link, information on the beacon frame of the non-primary link may not be indicated in each STA profile subelement corresponding to the non-primary link. That is, the beacon interval present subfield and the DTIM information present subfield of a specific respective STA profile sub-element (corresponding to an AP that is not a main link) transmitted by NSTR AP MLD may be indicated as 0 even though the full profile sub-field is indicated as 1.
Further, as described in the above embodiments, the non-AP STA MLD transmitting the ML probe request frame to NSTR AP MLD may request the changed information (updated information) of the non-main link AP from the AP of the main link by indicating the updated profile subfield of the STA control field (included in each STA profile subelement corresponding to the AP of the non-main link) as 1. At this time, the non-AP STA MLD may indicate the value of the recorded change sequence as information about the point of time at which the information of the non-main link AP is updated using the recorded change sequence subfield (see (c) of fig. 14). In this case, the recorded change sequence subfield may be a subfield included in the STA profile. After receiving the ML probe request frame received from the non-AP STA MLD through the main link, the NSTR AP MLD may determine information of the non-main link AP to be responded to the non-AP STA MLD by comparing the value of the recorded change sequence subfield included in the ML probe request frame with the change sequence value of the current non-main link AP.
Fig. 15 illustrates an example of a procedure in which a non-AP MLD of a non-simultaneous transmission and reception (NSTR) soft AP MLD set updates information of a non-primary link according to an embodiment of the present invention.
Referring to fig. 15, the nstr AP MLD may indicate that the parameters of the AP2 have been changed by a beacon frame transmitted by the AP1 operating on the link 1 (main link) after changing the parameters of the AP2 operating on the link 2 (non-main link). In this case, the information that the parameter of the AP2 has been changed may be indicated by increasing the value of the change sequence subfield corresponding to the AP2 in the RNR element included in the beacon frame transmitted by the AP1 by 1 from the value indicated in the previous beacon frame.
The non-AP STA MLD can recognize the fact that the parameters of the AP2 have been updated after receiving the beacon frame transmitted by the AP1 through the STA1. The non-AP STA MLD may transmit an ML probe request frame through the STA1 to acquire changed parameter information of the AP 2.
The ML probe request frame transmitted by the non-AP STA MLD through the STA1 may have a structure in which each STA profile sub-element corresponding to the AP2 is included in the ML element, and the each STA profile sub-element may include an indicator as to whether a complete profile or an update profile is requested.
After receiving the ML probe request frame from STA1 through the main link, NSTR AP MLD can respond to STA1 by including the requested information (full or updated information) of AP2 in the ML probe response frame.
After the non-AP STA MLD receives the information of AP2 requested by itself from NSTR AP MLD through the ML probe response frame, the parameter update for the non-primary link in which the beacon frame is not transmitted can be completed by updating the parameters regarding AP 2.
< broadcast ML probe response >
According to an embodiment of the present invention, NSTR AP MLD may transmit a broadcast ML probe response frame over a main link when information about APs operating on non-main links changes. When the non-AP STA MLD receives the broadcast ML probe response frame transmitted by NSTR AP MLD over the primary link, it may need to update information about the non-primary link (AP on). In this case, the broadcast ML probe response frame may not be transmitted in response to the ML probe request frame transmitted by the specific STA, but may be an ML probe request frame transmitted by NSTR AP MLD without a separate request.
The broadcast ML probe response frame includes STA profile sub-elements corresponding to APs that are not primary links and is used to assist non-AP STA MLDs in updating changed parameters and elements of the non-primary links. In this case, since the (recorded) change sequence of the non-primary link maintained by each non-AP STA may be different, the broadcast ML probe response frame may include complete information about the non-primary link's AP. In this case, the broadcast ML probe response frame may be transmitted with the DTIM beacon frame.
Thus, if it is confirmed by the beacon frame that the change sequence number corresponding to the AP of the non-master link is different from the (recorded) change sequence number maintained by the non-AP STA MLD itself, the non-AP STA MLD may need to receive the broadcast ML probe response frame upon receiving the next DTIM frame.
In this case, the above-described parameter update procedure of the non-primary link using the broadcast ML probe response frame may also be performed using the broadcast ML association response frame. In this case, the method of configuring each STA profile subelement of the broadcast ML association response frame and the update procedure of the receiving STA MLD are the same as those of the above-described embodiment of the broadcast ML probe response frame, and thus detailed description is omitted.
Fig. 16 is a flowchart illustrating one example of a procedure in which a non-AP STA MLD associated (Association) with NSTR AP MLD updates parameters of a non-primary link according to an embodiment of the present invention.
After the beacon frame is received on the primary link, the non-AP STA MLD acknowledges the non-primary link's change sequence (in the RNR element's MLD parameter field). If the confirmed changed sequence value of the non-main link is different from the changed sequence value recorded by the non-AP STA MLD, the non-AP STA MLD may transmit an ML probe request frame through the main link. At this time, the ML probe request frame may include a subfield indicating whether complete information of the non-main link AP is requested or update information is requested. Further, the ML probe request frame requesting update information may have subfields that simultaneously include the (recorded) change sequence value maintained by the indicator. Then, the non-AP STA MLD, which receives the ML probe response frame from the AP MLD, performs parameter update based on information of the non-main link AP included in the responsive ML probe response frame.
< time synchronization management of non-Main links >
As described above, the beacon frame transmitted by the AP may help STAs within the BSS to achieve time synchronization in addition to conveying various parameters and element information. The TimeStamp (TimeStamp) field included in the beacon frame indicates the value of the timing synchronization function (timing synchronization function, TSF) timer at the point in time when the data symbol including the first bit of the TimeStamp field appears on the transmit antenna connector, and the STA receiving the TimeStamp field may synchronize its TSF timer with the AP according to the received TimeStamp field value.
In this way, the AP and the STA can perform a timing-based operation while maintaining time synchronization based on the timestamp value included in the beacon frame. However, NSTR AP MLD cannot transmit beacon frames over the non-primary link, and therefore, among the STAs of NSTR AP MLD, the STA of the non-AP STA MLD associated with the non-primary link AP must remain time synchronized with the AP using a method other than the beacon frames.
To maintain time synchronization with the non-primary link AP of NSTR AP MLD, the associated non-AP STA may need to use the timestamp in the TIM frame sent by the AP. Since the TIM frame has a structure including a timestamp field having the same function as the beacon frame, a STA receiving the TIM frame from the non-main link AP of NSTR AP MLD may need to use the timestamp field included in the TIM frame to manage its TFS timer. However, in the case of NSTR AP MLD, transmission may be limited to being initiated on the non-primary link without occupying the primary link, and thus it may be desirable to transmit a TIM frame on the non-primary link at the same time as the beacon frame on the primary link. That is, the non-AP STA MLD associated with NSTR AP MLD may need to be ready to receive TIM frames on the non-primary link in coordination with the TBTT of the primary link.
In another embodiment of the present invention, if the AP MLD is NSTR AP MLD which does not support simultaneous transmission and reception, the same TSF timer may be used on each link of the plurality of APs included in NSTR AP MLD, and the TSF timer used at this time may be the TSF timer of the main link. That is, if the AP MLD is NSTR AP MLD, the link (non-primary link) of the AP attached to NSTR AP MLD may use the TSF timer of the primary link.
That is, the non-AP STA MLD associated with the NSTR soft AP MLD may need a TSF timer that shares the primary link with the non-primary link. In other words, the non-AP STA MLD associated with NSTR AP MLD may not have a separate TSF timer for the non-main link (NSTR-based softap MLD), but may use the TSF timer managed by the main link together. That is, in one aspect of the present invention, NSTR AP MLD and the non-AP STA MLD associated with NSTR AP MLD may use an MLD level (MLD unit, MLD common) timer. At this time, in order to ensure stable operation of NSTR AP MLD and the non-AP STA MLD associated with NSTR AP MLD, it may be required that the time synchronization (Time Syncronization) between the respective APs in NSTR AP MLD and/or between the respective STAs in the non-AP STA MLD associated with NSTR AP MLD remain below a pre-agreed value. For example, NSTR AP MLD may be required to keep the timestamp difference (or the difference between timers) maintained between an AP on the main link and an AP on the non-main link below a pre-agreed/set value. For example, the non-AP STA MLD associated with the NSTR softap MLD may be required to maintain the timestamp difference maintained between STAs on the primary link and STAs not on the non-primary link below a pre-agreed/set value.
In other words, the TSF timer of the main link may remain the same (or the same application or use) on the links of all APs included or affiliated in NSTR AP MLD. Further, the difference between the time stamps or TSF timers of any two APs among the APs included or affiliated in NSTR AP MLD may be limited to a specific value (e.g., 30 us).
That is, the TSF timers of all APs included or attached in NSTR AP MLD may be the same, the time stamps or the difference between the TSF timers or the clock drift (clock drift) between any two APs included or attached in the AP MLD or NSTR AP MLD (e.g., an AP on a main link and an AP on a non-main link) may be limited to a specific value (e.g., ±30 us), and in this case, the AP MLD or NSTR AP MLD may modify the time stamps or the TSF timers to ensure that the difference between the TSF timers or the clock drift is within the specific value.
In addition, when the non-AP STA MLD associated with NSTR AP MLD receives the TIM frame over the non-primary link, it may need to receive the next beacon frame transmitted over the primary link. More specifically, when the non-AP STA MLD receives a TIM frame through a STA that is not a master link and the value indicated by the check beacon field in the TIM frame action field is different from the check beacon value maintained by itself, it may be necessary to receive the next beacon frame transmitted over the master link. In this case, the next beacon frame may be a beacon frame transmitted corresponding to the TBTT of the main link, which exists after the point in time when the non-main link receives the conductive TIM frame. In this case, receiving the next beacon frame may mean accompanied by an operation of updating parameters of the non-primary link through each STA profile (corresponding to the AP of the non-primary link) included in the beacon frame. In this case, the parameter as the update subject may be limited to only the parameter related to the critical update.
< channel switch for non-primary link, channel silence procedure >.
As described above, NSTR AP MLD does not transmit a beacon frame in a non-main link, and thus, the operation of a BSS performed based on the transmission timing of the beacon frame may be different from the BSS operation of the normal AP MLD.
In conventional Wi-Fi, the operating channel frequency (operating band) of the BSS may be changed according to a procedure agreed between the AP and the STA. At this time, a conventional extended channel switching (Extended channel switching, ECS) operation may be utilized, and a channel switching mechanism newly defined in 11be may also be utilized. When the AP decides to change the operating channel of the BSS, it may inform its associated STAs to switch to a new channel and class of operation while maintaining the association between them by transmitting a beacon frame, a probe response frame, or an extended channel switch announcement frame, etc. In this case, the AP transmits an extended channel switch announcement element through a beacon frame, and indicates information about which numbered beacon frame is transmitted followed by performing channel switching (operating channel change) in a channel switch timing field of the element. If the AP includes a maximum channel switch time (MAX Channel Switch Time) element and an extended channel switch announcement (Extended Channel Switch Announcement) element in the beacon frame, the AP should transmit the first beacon frame on the new channel within the switch time field (of the maximum channel switch time element). I.e. the time interval between the beacon frame transmitted on the new channel and the last beacon frame transmitted on the current channel should be smaller than the time interval indicated by the switch time field.
Referring to the channel switching operation of the conventional Wi-Fi BSS described above, the AP of the BSS may indicate to the STA information about a new channel, information about a time of performing channel switching, and information about a time point of a first beacon frame transmitted on the new channel through a beacon frame transmitted on the current channel. Based on the channel switching related information included in the beacon frame transmitted by the AP, the STA of the BSS may move to a new channel within a prescribed period of time (period of time indicated by the AP) to complete the channel switching while maintaining association with the AP. As such, the channel switching procedure of the conventional Wi-Fi BSS is performed in such a manner that the beacon frame transmitted by the AP provides information (channel switching mode, new operation class, new channel number, channel switching timing, etc.) required for channel switching, and thus the non-main link BSS of NSTR AP MLD, which does not transmit the beacon frame, cannot perform channel switching using the conventional channel switching procedure.
Further, when the legacy Wi-Fi sets the mute interval, information on a period of time in which the mute interval is applied is also indicated by an element (mute element, mute channel element, etc.) included in a beacon frame transmitted by an AP of the BSS, and similarly to the channel switching procedure, the non-main link of NSTR AP MLD which does not transmit the beacon frame cannot set the mute interval using the legacy mute procedure.
According to an embodiment of the present invention, NSTR AP MLD may indicate information required to change an operating channel (channel switch) of a non-primary link and/or information required to set a silence interval by a beacon frame transmitted over a primary link. In other words, the non-AP STA MLD associated with NSTR AP MLD may perform channel switching of the non-primary link based on information obtained through the beacon frame of the primary link. In other words, the non-AP STA MLD associated with NSTR AP MLD may obtain information about the quiet interval of the non-primary link through the beacon frame of the primary link.
More specifically, when performing channel switching of a non-main link or setting a silence interval, NSTR AP MLD may include STA profiles for APs of the non-main link in a beacon frame (and (ML) probe response frame) of the main link.
Fig. 17 illustrates a format of elements according to an embodiment of the present invention. Fig. 17 illustrates one example of the format of each element described above.
Referring to fig. 17, each STA profile for (corresponding to) an AP that is not a main link may have a configuration including at least one of a channel switching announcement element, an extended channel switching announcement element, a maximum channel switching time element, a quiet element, and a quiet channel element.
The timing fields of the above elements may need to be set according to the target beacon transmission time (Target Beacon Transmission Time, TBTT) and beacon interval of the primary link.
The AP of the main link of NSTR AP MLD may set timing fields for the channel switch announcement element, the extended channel switch announcement element, the maximum channel switch time element, the quiet element, and the quiet channel element included in each STA configuration file (included in the beacon frame and (ML) probe response frame) of the AP of the non-main link according to its beacon interval and TBTT. In this case, the above-described timing fields are used to collectively refer to time-related fields including duration-related fields (switching time, silence duration field, etc.) and point-in-time-related fields (channel switching timing, silence timing field, etc.).
Accordingly, the non-AP MLD associated with NSTR AP MLD, upon receiving a Beacon frame from an AP operating on the main link NSTR AP MLD, may obtain information related to channel switching and/or silence interval of the non-main link from each STA profile included in the Beacon frame, and then interpret the information related to channel switching of the non-main link and/or the information related to silence interval according to the TBTT and Beacon Interval (BI) of the main link. In this case, each STA profile described above refers to each STA profile corresponding to an AP that is not a main link.
In addition, NSTR AP MLD may require that a TIM frame be sent on a new channel (of a non-primary link) within the time indicated by the switch time field (in the maximum channel switch time element) after the channel switch of the non-primary link is completed (after the announcement is completed) by the beacon frame of the primary link NSTR AP MLD. That is, the non-primary link AP of NSTR AP MLD may need to send TIM frames on the new channel after performing the channel switch. In this case, after transmitting a beacon frame in which the channel switch timer subfield is indicated as 1 (or 0) on the primary link, the non-primary link AP may need to transmit a TIM frame on the new channel for the time indicated by the switch time field. In this case, the channel switch timing field and the switch time field may be included in each STA profile (corresponding to the non-primary link AP) included in the beacon frame transmitted in the primary link. In this case, the TIM frame may be replaced by another frame transmitted on the new channel of the main link or the non-main link. For example, after the channel switch is completed on the non-main link, NSTR AP MLD may transmit a beacon frame indicating information related to the completion of the channel switch on the main link. In this case, the beacon frame may be an additional beacon frame transmitted independently of the TBTT. At this time, the beacon frame may be a beacon frame having a configuration including complete information about non-main link. For example, a beacon frame having a configuration including complete information about a non-primary link may be a beacon frame in which a complete information subfield of each STA profile corresponding to an AP of the non-primary link is set to 1. In this case, the beacon frame of the main link transmitted after the channel switching of the non-main link is ended may need to be transmitted within a predetermined time with respect to the beacon frame transmitted before the channel switching is started. At this time, the predetermined time may be a time indicated by a switching time field (in the maximum channel switching time element). Alternatively, the beacon frame may be a beacon frame including an indicator of channel switching with respect to a non-primary link. For example, a beacon frame of a primary link transmitted after a channel switch of a non-primary link is completed may have a configuration including a channel switch completion subfield. In this case, the channel switch completion subfield may be a subfield included in the ML element. The specific handover complete subfield may be a subfield indicated as 1 when the AP corresponding to each STA profile including the specific subfield completes channel handover. That is, after the channel switching of the non-main link is completed, the AP may need to set the channel switching completion subfield of each STA profile (in the beacon frame) corresponding to the AP of the non-main link to 1. In this case, even if the AP MLD is not NSTR AP MLD, i.e., the normal AP MLD, the beacon frame related to the above-described channel switching can be transmitted (used) for the same purpose.
After performing a channel switch of the non-primary link via the primary link, the non-AP MLD associated with NSTR AP MLD considers that the channel switch of the non-primary link is completed only when a committed frame (TIM frame or other frame of the non-primary link and/or beacon frame indicating information related to completion of the channel switch of the primary link) is received. If the channel switching is deemed not to be completed, the non-AP STA MLD may consider the channel switching of the non-primary link to be canceled and may operate on the previous channel (before performing the channel switching) (revert to the previous channel).
Alternatively, NSTR AP MLD may be limited to not set silence intervals on non-primary links. In this case, if there is a silence interval defined (set) for the main link, the silence interval for the non-main link may be defined (set) for the same period of time as the silence interval for the main link. That is, if the non-AP STA MLD knows the quiet interval of the main link, the non-AP STA MLD associated with NSTR AP MLD may consider that the same period of time in the non-main link is also set as the quiet interval.
Furthermore, NSTR AP MLD may not be able to perform channel switching for non-primary links. However, if NSTR AP MLD desires to perform a channel switch for a non-primary link, this may be accomplished by releasing the AP for the non-primary link operating on the existing channel and adding a new AP for the non-primary link on the new channel.
The mute element for the non-primary link transmitted over the beacon frame of the primary link may be set (indicated) by NSTR AP MLD as follows:
1. the Quiet timer (Quiet Count) field may be set to the number of TBTTs remaining before the non-main link until the start of the next Quiet interval.
2. The Quiet Period (Quiet Period) field may be set to a value (in units of a beacon interval of the main link) related to the start of a periodic (periodic) Quiet interval of the non-main link defined by a corresponding Quiet element every several main link beacon intervals. (in the case of an aperiodic silence interval, set to 0)
3. The Quiet Offset (quench Offset) field may be set to a time value (in TUs) related to how much Offset the non-primary link Quiet interval starts with respect to the TBTT of the primary link specified by the Quiet timer subfield.
The (extended) channel switch announcement element and maximum channel switch time element for non-primary link transmitted through the beacon frame of the primary link may be set (indicated) by NSTR AP MLD as follows:
1. the channel switch timing field (of the channel switch announcement element) may be set to information about how many TBTTs remain for the primary link before starting channel switch for the non-primary link. If channel switching for the non-primary link AP begins at the next TBTT of the primary link, the channel switching timing field (associated with the non-primary link AP) in the beacon frame sent in the current TBTT may be set to 1 or 0.
2. The switch time field (of the maximum channel switch time element) may be set to a value of the maximum time difference between the primary beacon frame (beacon frame with channel switch timing field set to 1 or 0 in 1 above) sent in the last TBTT of the TBTT at which channel switch of the non-primary link starts and the TIM frame transmitted on the new channel of the non-primary link after channel switch of the non-primary link is completed. For example, if the switch time field (of the non-main link AP) is set to 200ms when the beacon interval of the main link is 100ms, the AP of the non-main link must transmit the TIM frame on the new channel within 200ms after the beacon frame of the main link, where it starts channel switching, is transmitted.
Accordingly, after receiving the beacon frame through the primary link, the non-AP MLD associated with NSTR AP MLD may obtain information on the silence interval and channel switching time and period of the non-primary link based on information indicated in each STA profile of the non-primary link AP included in the beacon frame and the TBTT and beacon interval information of the primary link. At this time, the non-AP MLD may set (identify, interpret) a start time point of the silence interval of the non-main link based on the TBTT of the main link. At this time, the non-AP MLD may identify/interpret a channel switching time point of the non-primary link based on a reception time of the beacon frame received at the primary link.
In a conventional Wi-Fi non-AP STA, when an AP performs channel switching, the STA may select whether to perform channel switching together with the AP to maintain association with the AP. However, if NSTR AP MLD performs channel switching on the non-primary link, the non-AP STA MLD associated with NSTR AP MLD may have to perform channel switching on the non-primary link.
If the non-AP STA MLD that performs ML setup together with NSTR AP MLD (i.e., performs ML setup using the main link and the non-main link) decides not to perform channel switching of the non-main link, the non-AP STA MLD may need to end (cancel or change) ML setup with NSTR AP MLD and change to a state set only by the main link (by setting or resetting after the cancel).
Fig. 18 illustrates an example of a procedure in which the NSTR softap MLD sets (defines) a silence interval in a non-main link according to an embodiment of the present invention.
Referring to fig. 18, the nstr AP MLD operates AP1 and AP2 in a main link and a non-main link, respectively, and associates STA1 and STA2 with the non-AP STA MLD, respectively.
In order to set (define) the quiet interval (quiet interval #1 in fig. 18) in the non-main link, NSTR AP MLD may be transmitted by including STA profiles corresponding to AP2 in a beacon frame transmitted through AP1 of the main link. Each STA profile corresponding to the AP2 includes a muting element, and information related to a point in time at which a muting interval (muting interval #1 in fig. 18) starts is indicated by a muting timing and muting offset field. When the mute element is included in the first beacon frame (beacon #1 in fig. 18) of the main link shown in fig. 18, the mute timer field is set to 2, the mute offset field is set to a value representing "x" TUs (time units, 1024 us), and in the second beacon frame (beacon #2 in fig. 18), the mute timer field is set to 1.
By confirming the muting elements included in each STA profile (corresponding to AP 2) of the beacon frame, the non-AP STA MLD that received the first and/or second beacon frames through the main link can recognize that the muting interval (advertised by the AP MLD) has been set in the non-main link, and the muting interval (muting interval #1 in fig. 18) starts at a point in time after "x" TUs have passed after the TBTT corresponding to the third beacon frame.
As shown in fig. 18, NSTR AP MLD may be transmitted by including STA profiles corresponding to AP2 again in the beacon frame transmitted through AP1 of the main link to additionally set (define) the next quiet interval (quiet interval #2 in fig. 18) in the non-main link. In the sixth beacon frame (beacon #6 in fig. 18) of the main link shown in fig. 18, the silence timing field is set to 2, the silence offset field is set to a value indicating 0 TUs (time unit, 1024 us), and in the seventh beacon frame (beacon #7 in fig. 18), the silence timing field is set to 1.
By confirming the muting elements included in each STA configuration file of the beacon frame (corresponding to AP 2), the non-AP STA MLD that receives the sixth and/or seventh beacon frame through the main link can recognize that the muting interval (muting interval # 2) has been set (advertised by the AP MLD) in the non-main link, and the muting interval (muting interval # 2) starts from the TBTT corresponding to the eighth beacon frame.
In this case, information about the length of the muting interval is indicated by the muting duration field indicated together in the muting element.
Fig. 19 illustrates a method of the NSTR soft AP MLD performing channel switching of a non-main link according to an embodiment of the present invention.
Referring to fig. 19, the nstr AP MLD operates AP1 and AP2 in a main link and a non-main link, respectively, and associates STA1 and STA2 with the non-AP STA MLD, respectively.
To change the non-primary link to a new channel, NSTR AP MLD may be transmitted by including STA profiles corresponding to AP2 (non-primary link) in the beacon frame transmitted by AP1 of the primary link. Each STA profile corresponding to the AP2 includes a (extended) channel switching announcement element and a maximum channel switching time element, and indicates information about a time point at which channel switching starts and a time period after channel switching when a TIM frame is transmitted on a new channel. When the (extended) channel switch announcement element is included in the first beacon frame (beacon #1 in fig. 19) of the main link shown in fig. 19, the channel switch timing field is set to 2, and is set to 1 in the second beacon frame (beacon #2 in fig. 19).
By acknowledging the (extended) channel switch announcement element included in each STA profile (corresponding to AP 2) of the beacon frame, the non-AP STA MLD that received the first and/or second beacon frames over the primary link may recognize that channel switching (switching to the new channel) of the non-primary link begins after the second beacon frame is received and that the TIM frame of AP2 on the new channel will be received within "x" TUs after the second beacon frame is received. In this case, the new channel may be a channel corresponding to a value indicated by a new channel number field included in the (extended) channel switching announcement element. At this time, the above-mentioned "x" TUs may be a time value indicated by a switching time field included in the maximum channel switching time element included in each STA profile (corresponding to AP 2).
< restriction of operation of non-AP STA MLD associated with NSTR AP MLD >
NSTR AP MLD refers to AP MLD with primary and non-primary links in NSTR link pairs. Thus, when PPDU transmission is performed through an AP of a main link, an AP on a non-main link may be in a BLIND state; conversely, when an AP other than the main link performs transmission, the AP of the main link may be in a BLIND state. In this case, the AP experiencing NSTR AP MLD of the BLIND state may need to set the medium synchronization delay (medium synchronization delay) to a preset value.
The medium synchronization delay is a single timer that is commonly used by all EDCA functions (EDCA functions) of the STA, and when the medium synchronization delay is not 0, additional restrictions may be applied to the STA to obtain the TXOP. In this case, the additional restrictions may be: (1) the first transmission attempting to acquire a TXOP must be an RTS frame; (2) During the application of the medium synchronization delay (until it drops to 0), only a preset number of TXOP acquisition attempts or less are allowed; (3) A CCA ED (energy detection) threshold is employed that is more stringent (lower: e.g., -72dBm to-62 dBm) than when the media synchronization delay is 0. In other words, STAs with medium synchronization delay other than 0 are more restricted in acquiring a TXOP than STAs with medium synchronization delay of 0.
Therefore, even in the case of NSTR AP MLD, it may be necessary to apply a medium synchronization delay when the AP experiences a BLIND state, and it may be difficult to provide normal service to STAs in the BSS when the channel access of the AP is limited. NSTR AP MLD by determining one of the links in its NSTR link pair that operates the AP as the primary link, transmissions performed on non-primary links (other links than the primary link) can be managed in a manner that does not cause the primary link to become a BLIND state. For example, NSTR AP MLD may perform transmission on a non-main link only when the main link is transmitting, thereby managing such that the main link does not become a BLIND state. For this reason, NSTR AP MLD may not respond to the requested response frame even if the frame requesting the response frame is received through the AP that is not the main link. In other words, NSTR AP MLD can perform an operation of not responding to a response frame even if a frame requesting the response frame is received through an AP of a non-main link. In this case, the reason why NSTR AP MLD does not respond to the response frame by the AP of the non-main link may be to prevent the AP of the main link from becoming a BLIND state.
As described above, NSTR AP MLD can set up a main link and manage the operation (transmission) of APs operating on the main link and/or non-main link to ensure that the APs of the main link do not become a BLIND state. Likewise, the non-AP STA MLD associated with NSTR AP MLD may need to understand NSTR AP MLD the method of managing the primary link and operate. For example, if the non-AP STA MLD recognizes that a response frame is not received from NSTR AP MLD on the non-main link, a frame requesting a response frame may not be transmitted on the non-main link. In addition, if the non-AP STA MLD does not receive the response frame from NSTR AP MLD after the non-main link transmitted the frame requesting the response frame, the frame requesting the response frame may not be retransmitted. For example, the non-AP STA MLD may send an RTS frame to NSTR AP MLD over the non-primary link and not resend the RTS frame if a CTS frame response is not received. In this case, the non-AP MLD may not attempt to transmit to NSTR AP MLD over the non-main link until a trigger frame is received over the non-main link.
In addition, even if the non-AP MLD has completed the channel access procedure of the non-main link to perform UL transmission, it can defer transmission performed on the non-main link until the channel access procedure of the main link is completed. In this case, the method of the non-AP MLD deferring the transmission performed on the non-main link may be: . The backoff process performed by the STA of the non-primary link (more precisely, the EDCAF of the STA) is suspended until the backoff process performed by the STA of the primary link is completed. In this case, the method for the non-AP MLD to suspend the backoff procedure performed by the STA of the non-main link may be: the state in which the backoff counter is 0 is maintained.
By the method as described above, the non-AP STA MLD that completes the channel access procedure in both the primary link and the non-primary link can perform simultaneous transmission (simultaneous UL PPDU transmission) in both the primary link and the non-primary link. In this case, the above-mentioned "simultaneous transmission" means that the timing at which each transmission starts is within a preset time interval. However, if only the channel access procedure of the main link is completed, but the channel access procedure of the non-main link is not yet completed, the non-AP MLD may start PPDU transmission only at the main link, or may start simultaneous transmission when the channel access procedure of the non-main link is completed. That is, when the non-AP MLD performs transmission to NSTR AP MLD, the transmission may be performed using only the main link, or the simultaneous transmission may be performed using both the main link and the non-main link. However, the non-AP MLD may not allow PPDU transmission to be performed to NSTR AP MLD using only the non-main link.
Further, when the non-AP MLD performs UL transmission to NSTR AP MLD using both the main link and the non-main link, it may be necessary to coincide end time points of the transmission performed on both links. In this case, making the transmission end time points uniform may mean that the transmissions performed on the two links end together within a predetermined time interval.
In addition, when the non-AP MLD performs UL transmission to NSTR AP MLD using both the main link and the non-main link, it may be necessary to make the same setting as to whether PPDUs transmitted on both links request response frames. More specifically, the non-AP MLD may request a response frame for both UL PPDUs transmitted simultaneously on the primary link and the non-primary link, or may not request a response frame. This may be a limitation imposed for the reason that an AP operating on the other link of NSTR AP MLD may become a BLIND state only when responding to a response frame on a specific link as a result of non-AP MLD performing UL transmission using both the primary link and the non-primary link. However, if only one of two PPDUs received simultaneously (received through the main link and the non-main link, respectively) is a PPDU requesting a response frame response, no response of the response frame may be performed for both of the two PPDU, NSTR AP MLD.
Further, when the non-AP MLD performs transmission to the NSTR AP MLD using both the main link and the non-main link, it may be set such that the TXOP of the non-main link ends at the same time as the TXOP of the main link or earlier than the TXOP of the main link. In other words, the non-AP MLD may need to be set such that the TXOP of the non-primary link ends at the same time as or earlier than the TXOP of the primary link. However, the non-main link TXOP of the non-AP STA MLD may be allowed to end later than the main link TXOP by a time within a predetermined time interval.
In addition, the non-AP STA MLD may recognize that the AP on the specific link of NSTR AP MLD experiences a BLIND state and may assist the operation of the AP. More specifically, when the non-AP STA MLD recognizes NSTR AP MLD that transmission is performed through only one of the main link and the non-main link, the non-AP STA MLD may know that the AP of the other link, which does not perform transmission, has undergone the BLIND state. In this case, the non-AP STA MLD may perform an operation to assist in releasing (resetting to zero) the medium synchronization delay of the AP experiencing the BLIND state, considering that the AP experiencing the BLIND state will be restricted from channel access due to the medium synchronization delay other than 0. In this case, the operation performed by the non-AP STA MLD may be an operation utilizing the characteristic that the medium synchronization delay can be released when a PPDU (including a valid MPDU) with the NAV setting enabled is received.
For example, the non-AP STA MLD may transmit a NAV setting-enabled assistance frame (a PPDU) to an AP of NSTR AP MLD, which it determines to have a medium synchronization delay of non-0 after experiencing the BLIND state. In this case, the assistance frame may be any frame included in a valid MPDU with the NAV setting enabled, regardless of the frame format. At this time, the condition that the non-AP STA MLD transmits the assistance frame to NSTR AP MLD through the specific link may be limited to when the state of the specific link determined by the non-AP STA MLD is in an IDLE state. In this case, another condition for the non-AP STA MLD to transmit the assistance frame to NSTR AP MLD may be a case that is limited to the non-AP STA MLD being explicitly or implicitly requested (indicated) to transmit the assistance frame by NSTR AP MLD.
Fig. 20 is a flowchart illustrating one example of the operation of the non-AP MLD according to an embodiment of the present invention.
Referring to fig. 20, when a non-AP STA MLD including a plurality of stations receives information about another AP from a specific AP among AP MLDs including a plurality of APs, a TBTT offset included in the information about the another AP may be set to a value other than a specific value.
Specifically, a first Multi-link Device (MLD) including a plurality of stations operating on a plurality of links receives a beacon frame (beacon) through a first link of a first AP of a plurality of Access Points (APs) each included in a second MLD operating on one or more links (S20010).
Thereafter, a first multi-link device including a plurality of stations operating on the plurality of links may associate with one or more APs of the plurality of APs based on the received beacon frame (S20020).
In this case, the beacon frame may include at least one neighbor AP information field related to at least one AP other than the first AP among the plurality of APs and/or at least one AP not included in the second MLD.
Each of the at least one neighbor AP information field includes a neighbor AP TBTT offset subfield indicating an offset between a time when a beacon frame is transmitted (target beacon transmission time: TBTT) and a time when an AP reported by the neighbor AP information field transmits a next beacon frame.
The neighbor AP TBTT offset subfield may be set to a value other than the maximum value in a range of 0 to the maximum value that can be represented by bits allocated to the neighbor AP TBTT offset subfield.
In this case, the bit allocated to the neighbor AP TBTT offset subfield may be 8 bits, and the maximum value may be 255.
In other words, since an AP in the MLD can always recognize the TBTT offset of another AP in the MLD, when a neighbor AP TBTT offset subfield corresponding to another AP (in the same MLD) is indicated (set) by an RNR element, it should not be indicated (set) to 255. In other words, the neighbor AP TBTT offset subfield cannot be set to a specific value according to a specific condition.
For example, if included in the same AP MLD as the AP transmitting the beacon frame, the neighbor AP TBTT offset subfield cannot be set to a specific value (e.g., "255"). At this time, the size of the neighbor AP TBTT offset subfield may be 8 bits, in which case the neighbor AP TBTT offset subfield may not be set to the maximum value that the neighbor AP TBTT offset subfield can represent (in the case of 8 bits, corresponding to values of 0 to 255, so the maximum offset value that the 8 bits can represent may be 255). However, if not included in the same AP MLD as the AP transmitting the beacon frame (e.g., if the AP is a legacy AP, etc.), the neighbor AP TBTT offset subfield may be set to a specific value (e.g., "255").
In a similar embodiment, the setting of the neighbor AP TBTT offset subfield may be interpreted differently depending on the particular conditions.
For example, if the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the set value may be interpreted differently as "254" or greater than "254" depending on a specific condition. In other words, if the value of the neighbor AP TBTT offset subfield is set to 254, the offset indicated by the neighbor AP TBTT offset subfield may be 254 TUs or more than 254 TUs depending on the AP corresponding to the neighbor AP TBTT offset subfield.
Specifically, if an AP corresponding to the neighbor AP information field including the neighbor AP TBTT offset subfield is included in the same AP MLD as the AP transmitting the beacon frame or in a different MLD, and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs. However, if the AP is not included in the same AP MLD as the AP transmitting the beacon frame or in a different MLD (e.g., if the AP is a legacy AP or an AP not belonging to the MLD), and the neighbor AP TBTT offset subfield is set to a specific value (e.g., "254"), the station may interpret the value indicated by the neighbor AP TBTT offset subfield as 254 TUs or more.
The beacon frame may include a specific subfield related to capability, and the specific subfield may indicate whether the second MLD is a Non-STR (NSTR) MLD, i.e., an MLD that does not support Simultaneous Transmission and Reception (STR).
When the second MLD is an NSTR MLD, an update procedure of a parameter related to at least one link formed by at least one AP or association with at least one AP other than the first AP included in the second MLD is performed only through the first link. In this case, the first link may be a primary link and the at least one link may be a non-primary link.
When the second MLD is an NSTR MLD, at least one station associated with at least one AP among the plurality of stations and a first station associated with the first AP through the first link may apply one timing synchronization function (timing synchronization function, TSF) timer.
The difference between the time synchronization of the at least one link between the at least one AP and the first MLD and the reference value of the time synchronization of the first link of the first AP may be lower than a specific value.
The first MLD may transmit a multi-link (ML) probe request frame for requesting information related to at least one AP other than the first AP among the plurality of APs, only to the first AP among the plurality of APs.
Thereafter, in response, the first MLD may receive an ML probe response frame including information related to the at least one AP.
In this case, the ML probe request frame and the ML probe response frame include a multilink element including STA profile sub-elements corresponding to each of the at least one AP. Each STA profile sub-element includes a complete profile sub-field indicating whether all information related to at least one link of at least one AP is requested, and each STA profile sub-element of the ML probe response frame may further include a beacon interval present sub-field and a DTIM information present sub-field.
When the second MLD is an NSTR MLD and the full profile subfield indicates a request for all information, the beacon interval present subfield may be set to a value indicating that no beacon interval subfield exists in each STA profile subelement, and the DTIM information present subfield may be set to a value indicating that no DTIM information subfield exists in each STA profile subelement.
The above description of the present invention is for illustrative purposes, and it will be understood by those skilled in the art that the present invention may be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. Accordingly, it should be understood that the above-described embodiments are illustrative in all respects, rather than restrictive. For example, the constituent elements described as a single structure may be implemented as dispersed, or the constituent elements described as dispersed may be implemented as a combination.
The scope of the invention is defined by the appended claims, rather than by the detailed description, and all modifications or variations that come within the meaning and range of equivalency of the claims are intended to be embraced therein.
Claims (20)
1. A first multi-link device (MLD) comprising a plurality of stations operating on a plurality of links, respectively, wherein,
a processor:
receiving a beacon frame through a first link of a first Access Point (AP) among a plurality of APs respectively operating on one or more links included in a second MLD, and
based on the received beacon frame being associated with one or more of the plurality of APs,
wherein the beacon frame includes at least one neighbor AP information field associated with at least one AP other than the first AP and/or at least one AP not included in the second MLD among the plurality of APs,
each of the at least one neighbor AP information field includes a neighbor AP TBTT offset subfield indicating an offset between a time when the beacon frame is transmitted (target beacon transmission time: TBTT) and a time when the AP transmits a next beacon frame reported by the neighbor AP information field,
the neighbor AP TBTT offset subfield is set to a value other than the maximum value in a range of 0 to the maximum value that can be represented by bits allocated to the neighbor AP TBTT offset subfield.
2. The MLD of claim 1, wherein,
The bits allocated to the neighbor AP TBTT offset subfield are 8 bits, and
the maximum value is 255.
3. The MLD of claim 1, wherein,
when the value of the neighbor AP TBTT offset subfield is set to 254, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs or greater than 254 TUs depending on the AP corresponding to the neighbor AP TBTT offset subfield.
4. The MLD of claim 3, wherein,
when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs, and
when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP not included in an MLD among the at least one AP not included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is greater than 254 TUs.
5. The MLD of claim 1, wherein,
the beacon frame can include specific subfields related to capabilities, and
The specific subfield indicates whether the second MLD is a non-STR (NSTR) MLD which is an MLD that does not support Simultaneous Transmission and Reception (STR).
6. The MLD of claim 5, wherein,
when the second MLD is the NSTR MLD, performing an update procedure of a parameter associated with the at least one AP other than the first AP or at least one link formed with the at least one AP included in the second MLD through only the first link, and
the first link is a primary link and the at least one link is a non-primary link.
7. The MLD of claim 5, wherein,
when the second MLD is the NSTR MLD, at least one station associated with the at least one AP among the plurality of stations and a first station associated with the first AP through the first link apply a Timing Synchronization Function (TSF) timer.
8. The MLD of claim 7, wherein,
the difference between the time synchronization of the at least one link between the at least one AP and the first MLD and a reference value of the time synchronization of the first link of the first AP is below a specific value.
9. The MLD of claim 1, wherein the processor:
Transmitting a multi-link (ML) probe request frame for requesting information related to the at least one AP other than the first AP among the plurality of APs only to the first AP among the plurality of APs, and
in response, an ML probe response frame is received that includes information related to the at least one AP,
wherein the ML probe request frame and the ML probe response frame comprise a multi-link element comprising a respective STA profile sub-element corresponding to each of the at least one AP,
the STA profile sub-elements include a complete profile sub-field indicating whether all information related to at least one link of the at least one AP is requested,
each STA profile sub-element of the ML probe response frame further includes a beacon interval present sub-field and a DTIM information present sub-field.
10. The MLD of claim 9, wherein,
when the second MLD is the NSTR MLD, and the complete profile subfield indicates a request for all information,
the beacon interval present subfield is set to a value indicating that no beacon interval subfield exists in the respective STA profile sub-elements, and
The DTIM information present subfield is set to a value indicating that no DTIM information subfield exists in the STA profile subelement.
11. A method performed by a first multi-link device (MLD) in a wireless communication system, the first MLD comprising a plurality of stations respectively operating on a plurality of links, the method comprising:
receiving a beacon frame through a first link of a first Access Point (AP) among a plurality of APs included in a second MLD, which operate on one or more links, respectively; and
based on the received beacon frame being associated with one or more of the plurality of APs,
wherein the beacon frame includes at least one neighbor AP information field associated with at least one AP other than the first AP and/or at least one AP not included in the second MLD among the plurality of APs,
each of the at least one neighbor AP information field includes a neighbor AP TBTT offset subfield indicating an offset between a time at which the beacon frame is transmitted (target beacon transmission time: TBTT) and a time at which the AP reported by the neighbor AP information field transmits a next beacon frame, and
the neighbor AP TBTT offset subfield is set to a value other than the maximum value in a range of 0 to the maximum value that can be represented by bits allocated to the neighbor AP TBTT offset subfield.
12. The method of claim 11, wherein,
the bits allocated to the neighbor AP TBTT offset subfield are 8 bits, and
the maximum value is 255.
13. The method of claim 11, wherein,
when the value of the neighbor AP TBTT offset subfield is set to 254, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs or greater than 254 TUs depending on the AP corresponding to the neighbor AP TBTT offset subfield.
14. The method of claim 13, wherein,
when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is 254 TUs, and
when the value of the neighbor AP TBTT offset subfield is set to 254 and the AP corresponding to the neighbor AP TBTT offset subfield is an AP not included in an MLD among the at least one AP not included in the second MLD, the offset indicated by the neighbor AP TBTT offset subfield is greater than 254 TUs.
15. The method of claim 11, wherein,
The beacon frame can include specific subfields related to capabilities, and
the specific subfield indicates whether the second MLD is a non-STR (NSTR) MLD which is an MLD that does not support Synchronous Transmission and Reception (STR).
16. The method of claim 15, wherein,
when the second MLD is the NSTR MLD, performing an update procedure of a parameter associated with the at least one AP other than the first AP or at least one link formed with the at least one AP included in the second MLD through only the first link, and
the first link is a primary link and the at least one link is a non-primary link.
17. The method of claim 15, wherein,
when the second MLD is the NSTR MLD, at least one station associated with the at least one AP among the plurality of stations and a first station associated with the first AP through the first link are applied with a Timing Synchronization Function (TSF) timer.
18. The method of claim 17, wherein,
the difference between the time synchronization of the at least one link between the at least one AP and the first MLD and a reference value of the time synchronization of the first link of the first AP is below a specific value.
19. The method of claim 11, further comprising:
transmitting a multi-link (ML) probe request frame for requesting information related to the at least one AP other than the first AP among the plurality of APs only to the first AP among the plurality of APs, and
in response, an ML probe response frame is received that includes information related to the at least one AP,
wherein the ML probe request frame and the ML probe response frame comprise a multi-link element comprising a respective STA profile sub-element corresponding to each of the at least one AP,
the STA profile sub-elements include a complete profile sub-field indicating whether all information related to at least one link of the at least one AP is requested,
each STA profile sub-element of the ML probe response frame further includes a beacon interval present sub-field and a DTIM information present sub-field.
20. The method of claim 19, wherein,
when the second MLD is the NSTR MLD, and the complete profile subfield indicates a request for all information,
The beacon interval present subfield is set to a value indicating that no beacon interval subfield exists in the respective STA profile sub-elements, and
the DTIM information present subfield is set to a value indicating that no DTIM information subfield exists in the STA profile subelement.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2021-0054667 | 2021-04-27 | ||
| KR10-2021-0055314 | 2021-04-28 | ||
| KR10-2021-0147766 | 2021-11-01 | ||
| KR20210147766 | 2021-11-01 | ||
| PCT/KR2022/006058 WO2022231324A1 (en) | 2021-04-27 | 2022-04-27 | Wireless communication method using multilink, and wireless communication terminal using same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117223387A true CN117223387A (en) | 2023-12-12 |
Family
ID=89039414
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202280031685.9A Pending CN117223387A (en) | 2021-04-27 | 2022-04-27 | Wireless communication method using multilink and wireless communication terminal using the same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117223387A (en) |
-
2022
- 2022-04-27 CN CN202280031685.9A patent/CN117223387A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP4149198A1 (en) | Wireless communication method using multiple links, and wireless communication terminal using same | |
| US20230284303A1 (en) | Method and wireless communication terminal for transmitting/receiving data in wireless communication system | |
| KR102544254B1 (en) | Wireless communication method using multi-link and wireless communication terminal using the same | |
| KR102526879B1 (en) | Wireless communication method using multi-link and wireless communication terminal using the same | |
| EP4192179A1 (en) | Wireless communication method using multiple links, and wireless communication terminal using same | |
| US20240008119A1 (en) | Multi-link device operating in multiple links and method for operating multi-link device | |
| US20230389101A1 (en) | Method and wireless communication terminal for transmitting/receiving data in wireless communication system | |
| US20230354098A1 (en) | Method for transmitting/receiving data in wireless communication system, and wireless communication terminal | |
| EP4355013A1 (en) | Wireless communication method using multi-link, and wireless communication terminal using same | |
| EP4280775A1 (en) | Wireless communication method using limited twt and wireless communication terminal using same | |
| KR20230048064A (en) | Wireless communication method using multi-link and wireless communication terminal using the same | |
| US20240064837A1 (en) | Wireless communication method using multilink, and wireless communication terminal using same | |
| US20240129866A1 (en) | Wireless communication method using multilink, and wireless communication terminal using same | |
| CN117223387A (en) | Wireless communication method using multilink and wireless communication terminal using the same | |
| US20240114573A1 (en) | Wireless communication method using multi-link and wireless communication terminal using same | |
| CN117480854A (en) | Wireless communication method using multilink and wireless communication terminal using the same | |
| US20230319884A1 (en) | Wireless communication method using multiple links, and wireless communication terminal using same | |
| CN117322124A (en) | Wireless communication method using multiple links Wireless communication terminal using the same | |
| CN116746106A (en) | Method and terminal for transmitting and receiving data in wireless communication system | |
| CN117546590A (en) | Using sharing TXOP (TXOP) TXOP (TXOP) A kind of electronic device and use it Wireless communication terminal | |
| CN117561789A (en) | Wireless communication method using multilink and wireless communication terminal using the same | |
| CN116830754A (en) | Wireless communication method using multilink and wireless communication terminal using the same | |
| CN116803128A (en) | Wireless communication method using multilink and wireless communication terminal using the same | |
| CN116530173A (en) | Method for transmitting and receiving data through multiple links in wireless communication system and wireless communication terminal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |