Wireless communication method and wireless communication terminal using OFDM random access

Abstract

Disclosed is a wireless communication method and a wireless communication terminal using OFDM random access. The wireless communication terminal includes a transmitting / receiving unit and a processor. The processor sets an integer selected from the range from 0 to a value equal to or less than the OFDMA contention window (OCW) as a counter for random access, receives, via the transmitting / receiving unit, a trigger frame for triggering random access from a base station wireless communication terminal using one or more resource units (RUs) allocated to random access, decrements the value of the counter based on the one or more RUs allocated to random access, randomly selects, when the value of the counter is 0 or becomes 0, one or more RUs allocated to random access, and attempts to perform transmission to the base station wireless communication terminal using the selected RUs. At this time, an RU is a group of a plurality of subcarriers available for uplink transmission and downlink transmission.

Description

[0001] This application is a divisional application of the patent application with the application number 201780080498.9 (PCT / KR2017 / 015535), the international filing date of which is December 27, 2017, and the date of entry into the Chinese Patent Office is June 25, 2019, and the invention title is "Wireless communication method using OFDM random access and wireless communication terminal using the same". Technical Field

[0002] The present invention relates to a wireless communication method using OFDMA random access and a wireless communication terminal. Background Art

[0003] In recent years, with the expansion of the supply of mobile devices, wireless communication technologies that can provide fast wireless Internet services to mobile devices have attracted significant public attention. Wireless communication technologies allow mobile devices including smart phones, smart tablets, laptop computers, portable multimedia players, embedded devices, etc. to wirelessly access the Internet at home, in the company, or in a specific service-providing area.

[0004] One of the most well-known wireless communication technologies is wireless LAN technology. Since the initial wireless LAN technology was supported using a frequency of 2.4 GHz, the 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 11 Mbps when using a frequency in the 2.4 GHz band. After IEEE 802.11b was commercialized, IEEE 802.11a uses a frequency in the 5 GHz band instead of the 2.4 GHz band, reduces the impact of interference compared to the significantly congested frequency in the 2.4 GHz band, and increases the communication speed up to a maximum of 54 Mbps by using orthogonal frequency division multiplexing (OFDM) technology. However, IEEE 802.11a has the disadvantage that the communication distance is shorter than that of IEEE 802.11b. In addition, IEEE 802.11g uses a frequency in the 2.4 GHz band similar to IEEE 802.11b to achieve a maximum communication speed of 54 Mbps and satisfies backward compatibility to attract significant public attention, and further, it is superior to IEEE 802.11a in terms of communication distance.

[0005] In addition, as a technical standard established to overcome the limitations of communication speed pointed out as a weakness in wireless LANs, IEEE 802.11n has been provided. The purpose of IEEE 802.11n is to increase the speed and reliability of the network and extend the working distance of the wireless network. More specifically, IEEE 802.11n supports high throughput (HT) with a data processing speed of up to 540 Mbps or higher, and further, multiple-input multiple-output (MIMO) technology that uses multiple antennas on both the transmitting unit and the receiving unit based on multiple antennas in order to minimize transmission errors and optimize data speed. In addition, the standard can use a coding scheme that sends multiple overlapping copies of each other in order to improve data reliability.

[0006] As the supply of wireless LANs has become active and further, the applications using wireless LANs have diversified, the need for a new wireless LAN system that supports a higher throughput (very high throughput (VHT)) than the data processing speed supported by IEEE 802.11n has attracted public attention. Among them, IEEE 802.11ac supports a wide bandwidth (80 to 160 MHz) in the 5 GHz frequency band. The IEEE 802.11ac standard is only defined within the 5 GHz frequency band, but the initial 11ac chipset will even support operation in the 2.4 GHz frequency band for backward compatibility with existing 2.4 GHz frequency band products. Theoretically, according to this standard, the wireless LAN speed of multiple stations can reach up to 1 Gbps at maximum and the maximum single-link speed can reach up to 500 Mbps at maximum. This is achieved by expanding the concept of the wireless interface accepted by 802.11n, such as a wider wireless frequency bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256QAM). In addition, as a scheme for transmitting data by using the 60 GHz frequency band instead of the existing 2.4 GHz / 5 GHz, IEEE 802.11ad has been provided. IEEE 802.11ad is a transmission standard that provides a speed of up to 7 Gbps by using beamforming technology and is suitable for the transmission of high-bitrate moving image streams such as massive data or uncompressed HD video. However, since the 60 GHz frequency band is difficult to pass through obstacles, the disadvantage is that the 60 GHz frequency band can only be used between devices in a short-distance space.

[0007] Meanwhile, in recent years, as the next-generation wireless communication technology standard after 802.11ac and 802.11ad, discussions on providing high-efficiency and high-performance wireless communication technologies in high-density environments have been continuously carried out. That is, in the next-generation wireless communication technology environment, it is necessary to provide communication with high frequency efficiency indoors / outdoors in the presence of high-density terminals and access points (APs), and various technologies for realizing this communication are required.

[0008] In particular, as the number of devices using wireless communication technologies increases, it is necessary to efficiently use the predetermined channels. Therefore, what is needed is a technology that can efficiently use the bandwidth by simultaneously transmitting data between multiple terminals and an AP. Summary of the Invention

[0009] Technical Problem

[0010] An object of an embodiment of the present invention is to provide a wireless communication terminal using OFDMA random access.

[0011] Technical Solution

[0012] According to an embodiment of the present invention, a wireless communication terminal wirelessly communicating with a base station wireless communication terminal includes a transceiver and a processor. The processor is configured to set an integer selected from a range from 0 to a value equal to or less than an OFDMA contention window (OCW) as a counter for random access, receive, using the transceiver, a trigger frame for triggering random access using one or more resource units (RUs) allocated to the random access from the base station wireless communication terminal, decrement the value of the counter based on one or more RUs allocated for random access, randomly select one or more RUs allocated for random access when the value of the counter is 0 or reaches 0, and attempt to perform a transmission to the base station wireless communication terminal using the selected RUs. In this case, an RU is a group of multiple subcarriers available for uplink transmission and downlink transmission.

[0013] The processor may be configured to decrement the value of the counter based on one or more RUs allocated for random access and the capabilities of the wireless communication terminal.

[0014] The processor may be configured to decrement the value of the counter by the number of RUs among one or more RUs allocated for random access through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal.

[0015] When the value of the counter is 0 or reaches 0, the processor may be configured to randomly select any one of the RUs allocated for random access and through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal.

[0016] The capabilities of the wireless communication terminal include capabilities related to the bandwidth through which the wireless communication terminal can perform transmission.

[0017] The capabilities of the wireless communication terminal may include capabilities related to the length of the padding field included in the TB PPDU.

[0018] The capabilities of a wireless communication terminal may include capabilities related to modulation and coding schemes that the wireless communication terminal can perform for transmission.

[0019] The wireless communication terminal may be a wireless communication terminal non - associated with a base station wireless communication terminal. The processor may be configured to set the OCW minimum value, which is a parameter indicating the minimum value of the OCW, to a value that is a default value predetermined for the OCW minimum value, and set the OCW maximum value, which is a parameter indicating the maximum value of the OCW, to a value that is a default value predetermined for the OCW maximum value. In this case, the value predetermined for the OCW minimum value and the value predetermined for the OCW maximum value may not be values specified by the base station wireless communication terminal.

[0020] The wireless communication terminal may be a wireless communication terminal non - associated with a base station wireless communication terminal. When the wireless communication terminal communicates with a different base station wireless communication terminal different from the base station wireless communication terminal, the processor may be configured to initialize parameters for random access to the different wireless communication terminal. In this case, the parameters for random access may include a counter, the OCW minimum value, which is a parameter indicating the minimum value of the OCW, and the OCW maximum value, which is a parameter indicating the maximum value of the OCW.

[0021] When the wireless communication terminal communicates with the base station wireless communication terminal, the processor may be configured to set the OCW minimum value and the OCW maximum value according to information received from the base station wireless communication terminal. In this case, when the wireless communication terminal communicates with a different base station wireless communication terminal, the processor may be configured to set the OCW minimum value and the OCW maximum value according to information received from the different base station wireless communication terminal.

[0022] The wireless communication terminal is associated with a base station wireless communication terminal. In this case, the processor may be configured to set the OCW minimum value, which is a parameter indicating the minimum value of the OCW, and the OCW maximum value, which is a parameter indicating the maximum value of the OCW, according to information received from a base station wireless communication terminal different from the base station wireless communication terminal. Additionally, the different base station wireless communication terminal may belong to a multi - basic service set identifier (BSSID) set to which the base station wireless communication terminal belongs.

[0023] The processor may be configured not to decrement the value of the counter based on a trigger frame sent from a different base station wireless communication terminal.

[0024] The different base station wireless communication terminal may be a base station wireless communication terminal operating a BSS corresponding to the basic service set identifier (BSSID) transmitted by the multi - BSSID set.

[0025] The information received from different base station wireless communication terminals may not be the information indicated in the signaling field allocated for the BSS including the wireless communication terminal.

[0026] When the trigger frame indicates an uplink transmission of the wireless communication terminal, the processor may be configured not to decrement the value of the counter based on the trigger frame.

[0027] According to an embodiment of the present invention, a method of operating a wireless communication terminal that wirelessly communicates with a base station wireless communication terminal includes: setting an integer selected from a range from 0 to a value equal to or less than the value of the OFDMA contention window (OCW) as a counter for random access; receiving, from the base station wireless communication terminal, a trigger frame for triggering random access using one or more resource units (RUs) allocated for random access; decrementing the value of the counter based on the one or more RUs allocated for random access; randomly selecting one or more RUs allocated for random access when the value of the counter is 0 or reaches 0; and attempting to transmit to the base station wireless communication terminal using the selected RUs. In this case, an RU is a group of a plurality of subcarriers available for OFDM communication.

[0028] Decrementing the value of the counter may include decrementing the value of the counter based on the one or more RUs allocated for random access and the capabilities of the wireless communication terminal.

[0029] Decrementing the value of the counter based on the one or more RUs allocated for random access and the capabilities of the wireless communication terminal may include decrementing the value of the counter by the number of RUs among the one or more RUs allocated for random access through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal.

[0030] Randomly selecting one or more RUs allocated for random access may include randomly selecting any one of the RUs that is allocated for random access and through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal.

[0031] The wireless communication terminal may be a wireless communication terminal non-associated with the base station wireless communication terminal. The operating method may further include: setting the OCW minimum value, which is a parameter indicating the minimum value of the OCW, to a default value predetermined as the OCW minimum value, and setting the OCW maximum value, which is a parameter indicating the maximum value of the OCW, to a default value predetermined as the OCW maximum value. Additionally, the default value predetermined as the OCW minimum value and the default value predetermined as the OCW maximum value may not be values specified by the base station wireless communication terminal.

[0032] Beneficial effects

[0033] An embodiment of the present invention provides a wireless communication method using OFDMA random access and a wireless communication terminal using the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Shows a wireless LAN system according to an embodiment of the present invention.

[0035] Figure 2 Shows a wireless LAN system according to another embodiment of the present invention.

[0036] Figure 3 Shows a block diagram illustrating the configuration of a station according to an embodiment of the inventive concept.

[0037] Figure 4 Shows a block diagram illustrating the configuration of an access point according to an embodiment of the present invention.

[0038] Figure 5 Shows the process of a station setting up an access point and a link according to an embodiment of the present invention.

[0039] Figure 6 Shows the UL MU transmission of a wireless communication terminal according to an embodiment of the present invention.

[0040] Figure 7 Shows a specific trigger frame format according to an embodiment of the present invention.

[0041] Figure 8 Shows the specific formats of the common information field and the user information field of a trigger frame according to an embodiment of the present invention.

[0042] Figure 9 Shows the random access operation of a wireless communication terminal according to an embodiment of the present invention.

[0043] Figure 10 Shows the specific format of a UORA parameter set element according to an embodiment of the present invention.

[0044] Figure 11 Shows the specific format of a plurality of BSSID elements according to an embodiment of the present invention.

[0045] Figures 12 to 13 Shows the random access operation of a wireless communication terminal associated with a multi-BSSID set according to an embodiment of the present invention.

[0046] Figure 14 Shows the types of RUs and subcarrier indices that can be used when transmitting a PPDU with a 20 MHz bandwidth according to an embodiment of the present invention.

[0047] Figure 15Shows the types of RUs and subcarrier indices that can be used when transmitting a PPDU with a 40 MHz bandwidth according to an embodiment of the present invention.

[0048] Figure 16 Shows the types of RUs and subcarrier indices that can be used when transmitting a PPDU with an 80 MHz bandwidth according to an embodiment of the present invention.

[0049] Figure 17 Shows the coding values of the RUs in the RU allocation subfield for indicating a trigger frame according to an embodiment of the present invention.

[0050] Figures 18 to 19 Shows the operation of a wireless communication terminal that only supports PPDUs with a 20 MHz bandwidth to perform random access according to an embodiment of the present invention.

[0051] Figures 20 to 21 Shows the operation of a wireless communication terminal that only supports PPDUs with a bandwidth of 80 MHz or less to perform random access according to an embodiment of the present invention.

[0052] Figure 22 Shows the random access operation of a non-associated wireless communication terminal according to an embodiment of the present invention.

[0053] Figure 23 Shows the random access operation of a non-associated wireless communication terminal according to an embodiment of the present invention.

[0054] Figure 24 Shows the random access operation of a non-associated wireless communication terminal according to an embodiment of the present invention.

[0055] Figure 25 Shows the random access operation of a non-associated wireless communication terminal according to an embodiment of the present invention.

[0056] Figure 26 Shows the random access operation of a wireless communication terminal when the wireless communication terminal schedules an uplink transmission through a trigger frame according to an embodiment of the present invention. Figure 27 Shows a conventional PPDU format according to an embodiment of the present invention.

[0057] Figure 28 Shows a non-conventional PPDU format according to an embodiment of the present invention.

[0058] Figure 29 Shows the coverage range of a HE extended range SU PPDU and the transmission coverage range of a conventional PPDU according to an embodiment of the present invention.

[0059] Figure 30 Shows the dual beacon transmission operation of a base station wireless communication terminal according to an embodiment of the present invention.

[0060] Figure 31 Shows the format of the BSS color change announcement element according to an embodiment of the present invention.

[0061] Figure 32 Shows the BSS color change operation of the base station wireless communication terminal when the base station wireless communication terminal uses a dual beacon according to an embodiment of the present invention.

[0062] Figure 33 Shows the BSS color change operation of the base station wireless communication terminal when the base station wireless communication terminal uses a dual beacon according to another embodiment of the present invention.

[0063] Figure 34 Shows the BSS color change operation of the base station wireless communication terminal when the base station wireless communication terminal uses a dual beacon according to another embodiment of the present invention.

[0064] Figure 35 Shows the format of the A-MPDU according to an embodiment of the present invention.

[0065] Figure 36 Shows the specific format of the block Ack according to an embodiment of the present invention.

[0066] Figure 37 Shows the per STA information subfield according to an embodiment of the present invention.

[0067] Figure 38 Shows the context of the per STA information subfield according to an embodiment of the present invention.

[0068] Figures 39 to 40 Shows the A-MPDU configuration according to an embodiment of the present invention.

[0069] Figure 41 Shows the operation of the wireless communication terminal according to an embodiment of the present invention. Detailed Description of the Invention

[0070] Preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Parts irrelevant to the description are omitted in the drawings for a clear description of the present invention, and like reference numerals refer to like elements throughout.

[0071] In addition, when it is described that a thing includes (or contains or has) some elements, it should be understood that if there is no specific limitation, it may include (or contain or have) only those elements, or it may include (or contain or have) other elements as well as those elements.

[0072] This application claims the priority and benefits of Korean Patent Application Nos. 10-2016-0179781 (filed on Dec. 27, 2016), 10-2017-0000020 (filed on Jan. 2, 2017), 10-2017-0000437 (filed on Jan. 2, 2017), 10-2017-0002195 (filed on Jan. 6, 2017), and 10-2017-0002720 (filed on Jan. 9, 2017) submitted to the Korean Intellectual Property Office, and the embodiments described and the items mentioned in the corresponding applications are included in the detailed description of this application.

[0073] Figure 1 FIG. is a diagram of a wireless communication system according to an embodiment of the present invention. For convenience of description, embodiments of the present invention are described by way of a wireless LAN system. The wireless LAN system includes one or more basic service sets (BSSs), and a BSS represents a set of devices that have successfully synchronized with each other to communicate with each other. Generally, BSSs can be classified into infrastructure BSSs and independent BSSs (IBSSs), and Figure 1 FIG. illustrates an infrastructure BSS among them.

[0074] As Figure 1 illustrated, the infrastructure BSSs (BSS1 and BSS2) include one or more stations STA1, STA2, STA3, STA4, and STA5, access points PCP / AP-1 and PCP / AP-2 as stations providing distribution services, and a distribution system (DS) connecting the multiple access points PCP / AP-1 and PCP / AP-2.

[0075] A station (STA) is a predetermined device including a media access control (MAC) that follows the procedures of the IEEE 802.11 standard and a physical layer interface for a wireless medium, and in a broad sense includes a non-access point (non-AP) station and an access point (AP). Additionally, in this specification, the term "terminal" may be used to refer to a concept including a wireless LAN communication device such as a non-AP STA or an AP or both terms. A station for wireless communication includes a processor and a transceiver, and according to this embodiment, may further include a user interface unit and a display unit. The processor may generate frames to be transmitted through a wireless network or process frames received through a wireless network, and furthermore, execute various processes for controlling the station. In addition, the transceiver is functionally connected to the processor and transmits and receives frames through the wireless network for the station.

[0076] An access point (AP) is an entity that provides access to a distribution system (DS) for stations associated with it via a wireless medium. In an infrastructure BSS, communication between non-AP stations is in principle performed via the AP, but when a direct link is configured, direct communication can also be achieved even between non-AP stations. At the same time, in the present invention, the AP is used as a concept including a personal BSS coordination point (PCP) and may include, in a broad sense, concepts including a centralized controller, a base station (BS), a Node B, a base transceiver system (BTS), and a site controller.

[0077] Multiple infrastructure BSSs can be connected to each other via a distribution system (DS). In this case, the multiple BSSs connected via the distribution system are called an extended service set (ESS).

[0078] Figure 2 FIG. illustrates a stand-alone BSS as a wireless communication system according to another embodiment of the present invention. For convenience of description, another embodiment of the present invention is described by a wireless LAN system. In Figure 2 the embodiment of, the repeated description of parts that are the same as or corresponding to the Figure 1 embodiment of will be omitted.

[0079] Since Figure 2 the BSS3 illustrated in is a stand-alone BSS and does not include an AP, all stations STA6 and STA7 are not connected to the AP. The stand-alone BSS is not permitted to access the distribution system and forms a complete network. In the stand-alone BSS, the corresponding stations STA6 and STA7 can be directly connected to each other.

[0080] Figure 3 is a block diagram illustrating the configuration of a station 100 according to an embodiment of the present invention.

[0081] As Figure 3 illustrated in, the station 100 according to an embodiment of the present invention may include a processor 110, a transceiver 120, a user interface unit 140, a display unit 150, and a memory 160.

[0082] First, the transceiver 120 transmits and receives wireless signals such as wireless LAN physical layer frames and can be embedded in the station 100 or set externally. According to this embodiment, the transceiver 120 may include at least one transmit and receive module using different frequency bands. For example, the transceiver 120 may include transmit and receive modules having different frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz. According to an embodiment, the station 100 may include a transmit and receive module using a frequency band of 6 GHz or higher and a transmit and receive module using a frequency band of 6 GHz or lower. The corresponding transmit and receive modules may perform wireless communication with an AP or an external station according to the wireless LAN standard of the frequency band supported by the corresponding transmit and receive module. The transceiver 120 may operate only one transmit and receive module at a time or operate multiple transmit and receive modules simultaneously according to the performance and requirements of the station 100. When the station 100 includes multiple transmit and receive modules, each transmit and receive module may be implemented by independent elements or multiple modules may be integrated into one chip.

[0083] 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 input by using various input devices and the processor 110 may control the station 100 based on the received user input. In addition, the user interface unit 140 may perform output based on the command of the processor 110 by using various output devices.

[0084] Next, the display unit 150 outputs an image on the display screen. The display unit 150 may output various display objects such as the content executed by the processor 110 or the user interface based on the control command of the processor 110 and the like. In addition, the memory 160 stores control programs used in the station 100 and various resultant data. The control program may include an access program required for the station 100 to access an AP or an external station.

[0085] The processor 110 of the present invention can execute various commands or programs and process data in the station 100. Additionally, the processor 110 can control corresponding units of the station 100 and control data transmission / reception between these units. According to an embodiment of the present invention, the processor 110 can execute a program for accessing an AP stored in the memory 160 and receive a communication configuration message sent by the AP. Additionally, the processor 110 can read information about the priority conditions of the station 100 included in the communication configuration message and request access to the AP based on the information about the priority conditions of the station 100. The processor 110 of the present invention can represent the main control unit of the station 100 and, according to this embodiment, the processor 110 can represent a control unit for individually controlling a certain component (e.g., the transceiver 120, etc.) of the station 100. The processor 110 can be a modulator and / or demodulator that modulates wireless signals sent to the transceiver 120 and demodulates wireless signals received from the transceiver 120. The processor 110 controls various operations of wireless signal transmission / reception of the station 100 according to an embodiment of the present invention. Detailed embodiments thereof will be described below.

[0086] Figure 3 The station 100 illustrated in is a block diagram according to an embodiment of the present invention, where individual blocks are illustrated as logically distinct elements of the device. Therefore, the elements of the device can be installed in a single chip or multiple chips depending on the design of the device. For example, the processor 110 and the transceiver 120 can be integrated into a single chip or implemented as separate chips. Additionally, in an embodiment of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, can be optionally provided in the station 100.

[0087] Figure 4 is a block diagram illustrating the configuration of an AP 200 according to an embodiment of the present invention.

[0088] As Figure 4 illustrated, the AP 200 according to an embodiment of the present invention can include a processor 210, a transceiver 220, and a memory 260. In Figure 4 Among the components of the AP 200, a repeated description of parts that are the same as or corresponding to the components of Figure 2 the station 100 will be omitted.

[0089] Referring to Figure 4 According to the present invention, the AP 200 includes a transceiver 220 for operating a BSS in at least one frequency band. As Figure 3As described in the embodiments, the transceiver 220 of the AP 200 may also include multiple transmit and receive modules using different frequency bands. That is, the AP 200 according to an embodiment of the present invention may include two or more transmit and receive modules among different frequency bands (e.g., 2.4 GHz, 5 GHz, and 60 GHz) together. Preferably, the AP 200 may include a transmit and receive module using a frequency band of 6 GHz or higher and a transmit and receive module using a frequency band of 6 GHz or lower. The corresponding transmit and receive modules may perform wireless communication with a station according to the wireless LAN standard of the frequency band supported by the corresponding transmit and receive module. The transceiver 220 may operate only one transmit and receive module at a time or operate multiple transmit and receive modules simultaneously according to the performance and requirements of the AP 200.

[0090] Next, the memory 260 stores control programs used in the AP 200 and various result-obtained data. The control program may include an access program for managing the access of stations. In addition, the processor 210 may control the corresponding units of the AP 200 and control data transmission / reception between these units. According to an embodiment of the present invention, the processor 210 may execute a program for accessing a station stored in the memory 260 and send a communication configuration message for one or more stations. In this case, the communication configuration message may include information about the access priority conditions of the corresponding stations. In addition, the processor 210 performs access configuration according to the access request of the station. The processor 210 may be a modulator and / or demodulator that modulates a wireless signal sent to the transceiver 220 and demodulates a wireless signal received from the transceiver 220. The processor 210 controls various operations such as radio signal transmission / reception of the AP 200 according to the first embodiment of the present invention. Detailed embodiments thereof will be described below.

[0091] Figure 5 is a diagram schematically illustrating the process of a STA setting a link with an AP.

[0092] Reference Figure 5 , the link between the STA 100 and the AP 200 is generally set through three steps: scanning, authentication, and association. First, the scanning step is a step in which the STA 100 obtains access information of the BSS operated by the AP 200. The methods for performing scanning include a passive scanning method in which the AP 200 obtains information by using beacon messages sent periodically (S101) and an active scanning method in which the STA 100 sends a probe request to the AP (S103) and obtains access information by receiving a probe response from the AP (S105).

[0093] The STA 100 that has successfully received the wireless access information in the scanning step performs an authentication step by sending an authentication request (S107a) and receiving an authentication response (S107b) from the AP 200. After the authentication step is performed, the STA 100 performs an association step by sending an association request (S109a) and receiving an association response (S109b) from the AP 200. In this specification, association basically means wireless combination, but the present invention is not limited thereto, and in a broad sense, it can include both wireless combination and wired combination.

[0094] Meanwhile, an 802.1X-based authentication step (S111) and an IP address acquisition step (S113) via DHCP can be additionally performed. In Figure 5 this case, the authentication server 300 is a server that processes 802.1X-based authentication for the STA 100 and can exist physically associated with the AP 200 or as a separate server.

[0095] In a specific embodiment, the AP 200 can be a wireless communication terminal that allocates communication media resources and performs scheduling in an independent network (such as an ad hoc network) not connected to an external distribution service. In addition, the AP 200 can be at least one of a base station, an eNB, and a transmission point TP. The TP 200 can also be referred to as a base station communication terminal.

[0096] The base station wireless communication terminal can be a wireless communication terminal that allocates and schedules media resources for communication with multiple wireless communication terminals. Specifically, the base station wireless communication terminal can be used as a cell coordinator. In a specific embodiment, the base station wireless communication terminal can be a wireless communication terminal that allocates and schedules communication media resources in an independent network (such as an ad hoc network) not connected to an external distribution service.

[0097] The base station wireless communication terminal can communicate with multiple wireless communication terminals simultaneously using orthogonal frequency division multiple access (OFDMA) or multi-user multiple input multiple output (MU-MIMO). In this case, the base station wireless communication terminal can send trigger information to the multiple wireless communication terminals to trigger uplink (UL) multi-user (MU) transmission using the OFDMA of the multiple wireless communication terminals. This will be described with reference to Figure 6 this.

[0098] Figure 6 Shows the UL MU transmission of a wireless communication terminal according to an embodiment of the present invention.

[0099] The base station wireless communication terminal can send trigger information to multiple wireless communication terminals to trigger UL MU transmissions of the multiple wireless communication terminals. Specifically, the base station wireless communication terminal can send trigger information to multiple wireless communication terminals to trigger the multiple wireless communication terminals to simultaneously send immediate response frames. In this case, the immediate response can indicate that the response frame is sent within a predetermined time from when the trigger information is received in the same transmission opportunity (TXOP). In this case, the predetermined time can be the short inter-frame space (SIFS) defined in the 802.11 standard. The base station wireless communication terminal is capable of using a trigger frame to send the trigger information. In addition, the base station wireless communication terminal can use the MAC header to send the trigger information.

[0100] The multiple wireless communication terminals can use a trigger-based (TB) PPDU to send a response frame for the trigger information. In this case, the multiple wireless communication terminals can send the TB PPDU after a predetermined time from when the trigger information is received. Additionally, the multiple wireless communication terminals can use at least one of UL OFDMA and UL MU-MIMO to send the TB PPDU. When the trigger type of the trigger information is sent through a MU-request to send (RTS) frame, the multiple wireless communication terminals are capable of using a non-HT PPDU to send a response frame for the MU-RTS frame.

[0101] In Figure 6 an embodiment, the AP sends a trigger frame to the first station STA1, the second station STA2, the third station STA3, and the fourth station STA4. The first station STA1, the second station STA2, the third station STA3, and the fourth station STA4 receive the trigger frame. When SIFS has elapsed since the trigger frame was received, the first station STA1, the second station STA2, the third station STA3, and the fourth station STA4 send a HE trigger-based PPDU (TB PPDU). The AP receives the HE trigger-based PPDU (TB PPDU) and sends an ACK to the first station STA1, the second station STA2, the third station STA3, and the fourth station STA4.

[0102] As described above, the base station wireless communication terminal can use a trigger frame or the MAC header to send the trigger information. Specifically, the base station wireless communication terminal can use the UL MU response scheduling (UMRS) A-control subfield of the MAC header to send the trigger information. In a specific embodiment, the wireless communication terminal that receives a MAC frame including the UMRS A-control subfield sends a TB PPDU in response to the UMRS A-control subfield. In addition, the wireless communication terminal indicated by the user information field of the trigger frame can send a TB PPDU in response to the trigger frame. The specific format of the trigger frame will be described in detail with reference to Figure 7 The specific format of the trigger frame will be described in detail with reference to

[0103] Figure 7 Shows a specific trigger frame format according to an embodiment of the present invention.

[0104] The trigger frame may include at least one of a frame control field, a duration field, an RA field, a TA field, a common information field, a user information field, a padding field, and an FCS field. Depending on the trigger type, the response to the trigger frame request may vary. Additionally, the fields included in the trigger frame may vary depending on the trigger type.

[0105] The RA field indicates the receiver address of the trigger frame. When the trigger frame triggers the transmission of a wireless communication terminal, the RA field may indicate the MAC address of the corresponding wireless communication terminal. When the trigger frame triggers the transmission of two or more wireless communication terminals, the RA field may indicate the broadcast address. When the trigger type of the trigger frame is GCR MU-BAR, the RA field may indicate the group address corresponding to the multiple wireless communication terminals triggered by the trigger frame.

[0106] The TA field indicates the transmitter address of the trigger frame. When the wireless communication terminal transmitting the trigger frame does not use multiple BSSIDs, the TA field may indicate the MAC address of the wireless communication terminal transmitting the trigger frame. Additionally, when the wireless communication terminal transmitting the trigger frame uses multiple BSSIDs and the trigger frame triggers multiple wireless communication terminals of a multi-BSSID set, the TA field may indicate the BSSID of the wireless communication of the multi-BSSID set to which the terminal transmitting the trigger frame belongs. In this case, the transmitted BSSID indication may signal the BSS that sends information about other BSSs included in the multi-BSSID set. The identifier of the BSS among the BSSs included in the multi-BSSID set that does not correspond to the transmitted BSSID is the non-transmitted BSSID. Specifically, the base station wireless communication terminal operating the BSS corresponding to the transmitted BSSID may signal information about the BSS corresponding to the non-transmitted BSSID using multiple BSSID elements. The management frame transmitted from the BSS corresponding to the transmitted BSSID may include multiple BSSID elements. In this case, the management frame may include a beacon frame and a probe response frame. Additionally, there may be a transmitted BSSID for each multi-BSSID set. A more detailed description will be made with reference to Figure 11 This will be described in more detail.

[0107] The common information field indicates the information generally required for at least one wireless communication terminal triggered by the trigger frame to send a response to the trigger frame. The user information field respectively indicates the information required for each of the multiple wireless communication terminals indicated by the trigger frame to send a response to the trigger frame. Specifically, the trigger frame may include multiple user information fields. A more detailed description of the specific formats of the common field and the user information field will be made with reference to Figure 8 Describe the specific formats of the common field and the user information field.

[0108] The padding field includes padding bits. Specifically, the padding field can help ensure the time for a wireless communication terminal that sends a response frame for a trigger frame to prepare for response frame transmission. Therefore, the length of the padding field can be determined according to the capabilities of the wireless communication terminal that sends a response frame for a trigger frame. In addition, the trigger frame may not include a padding field. The padding field can indicate the start of the padding field with a predetermined value. In this case, the predetermined value can be 0xFFF. Additionally, the remaining fields of the padding field other than the padding field including the predetermined value can include values other than the predetermined value or the predetermined value.

[0109] The specific format of the trigger frame can be the same as Figure 7 the format of the embodiment of

[0110] Figure 8 FIG. shows the specific formats of the common information field and the user information field of the trigger frame according to an embodiment of the present invention.

[0111] Specifically, the format of the common information field and the format of the user information field according to an embodiment of the present invention can be the same as those shown in Figure 8 (a) and Figure 8 (b) respectively. The user information field can indicate the wireless communication terminal triggered by the trigger frame. Specifically, when the user information field includes the association identifier (AID) of the wireless communication terminal or a part of the AID, the wireless communication terminal corresponding to the AID can determine that the trigger frame triggers the wireless communication terminal. In a specific embodiment, the AID12 subfield in the user information field can indicate the 12 least significant bits (LSBs) of the AID of the wireless communication terminal triggered by the trigger frame.

[0112] In addition, the user information field can indicate the resource unit (RU) allocated to the wireless communication terminal triggered by the trigger frame. The RU can indicate that multiple subcarriers available for uplink and downlink transmission can be grouped according to the size of the frequency band. In this case, in uplink transmission and downlink transmission, at least one of OFDM, OFDMA, and MU-MIMO can be used. Additionally, the grouping can be referred to as subchannelization. In a specific embodiment, the RU allocation subfield can indicate the RU allocated to the wireless communication terminal indicated by the AID12 subfield.

[0113] The base station wireless communication terminal can use a trigger frame to trigger the uplink transmission of any wireless communication terminal. Specifically, the base station wireless communication terminal can trigger a random access to a specified RU. In this case, the base station wireless communication terminal can set the user information field of the trigger frame to indicate a predetermined value instead of the AID of a specific wireless communication terminal. In a specific embodiment, the base station wireless communication terminal can set the AID12 subfield of the user information field of the trigger frame to a predetermined value. Additionally, when the user information field of the trigger frame indicates a predetermined value instead of the AID of a specific wireless communication terminal, the wireless communication terminal receiving the trigger frame is capable of randomly accessing the RU indicated by the corresponding user information field. In a specific embodiment, when the AID12 subfield of the user information field of the trigger frame received by the wireless communication terminal indicates a predetermined value, the wireless communication terminal randomly accesses the RU indicated by the RU allocation subfield of the corresponding user information field. The predetermined value can be 0. Additionally, the predetermined value can be 2045. Specific operations of the wireless communication terminal performing random access based on the trigger frame will be described with reference to Figure 9 Describe the specific operations of the wireless communication terminal performing random access based on the trigger frame.

[0114] Figure 9 Illustrate the random access operation of the wireless communication terminal according to an embodiment of the present invention.

[0115] A wireless communication terminal may perform an OFDMA random access operation through the following operations. The wireless communication terminal selects an arbitrary integer within an OFDMA contention window (OCW). Specifically, the wireless communication terminal may select a random integer from 0 to a value equal to or less than the OCW value. In this case, the OCW may be equal to or greater than the OCW minimum value OCWmin, or may be equal to or less than the OCW maximum value OCWmax, which is a positive integer. The wireless communication terminal sets the selected number as an OFDMA random access backoff (OBO) counter. The wireless communication terminal may receive a trigger frame and decrement the OBO counter based on the RU indicated for random access in the trigger frame. Specifically, the wireless communication terminal may receive a trigger frame and decrement the OBO counter by the number of RUs indicated for random access in the trigger frame. When the OBO counter is 0 or reaches 0, the wireless communication terminal may randomly select any one of the RUs indicated for random access and attempt to transmit through the selected RU. In this case, the wireless communication terminal may determine whether the selected RU is idle, and when the selected RU is idle, may send a pending frame of the base station wireless communication terminal to the base station wireless communication terminal through the selected RU. Additionally, when the wireless communication terminal determines that the corresponding RU is busy through physical carrier sensing or virtual carrier sensing, the wireless communication terminal may determine that the corresponding RU is busy. Physical carrier sensing may include clear channel assessment (CCA). Additionally, physical carrier sensing may include energy detection (ED). When it is determined that the RU selected by the wireless communication terminal is busy, the wireless communication terminal may maintain the OBO counter at 0 without sending the pending frame to the base station wireless communication.

[0116] The wireless communication terminal may set OCWmin and OCWmax according to OBO-related parameter values signaled by a base station wireless communication terminal associated with the wireless communication terminal. Additionally, when the wireless communication terminal attempts random access for the first time, the wireless communication terminal receives OBO-related parameters signaled by the base station wireless communication terminal, or when the wireless communication terminal successfully transmits through random access, the wireless communication terminal may be allowed to initialize the OBO process. In this case, the initialization of the OBO process may include at least one of the initialization of the OBO counter and the initialization of the OCW. Additionally, when the wireless communication terminal initializes the OCW, the wireless communication terminal may set the OCW to OCWmin. When the transmission through the random access of the wireless communication terminal fails, the wireless communication terminal may update the value of the OCW to (2×OCW + 1). In this case, the wireless communication terminal selects a random integer within the updated OCW and sets the selected random integer as the OBO counter. Additionally, when the value of the OCW reaches OCWmax, even if the transmission through the random access of the wireless communication terminal fails, the wireless communication terminal may maintain the OCW at OCWmax.

[0117] In Figure 9 the embodiment, the OBO counter of the first station STA1 is 5 and the OBO counter of the second station STA2 is 1. The AP sends a trigger frame that triggers the random access of the first RU RU 1 and the second RU RU 2. Since the number of RUs allocated for random access is 2, the first station STA1 decrements the OBO counter by 2 and sets the OBO counter to 3, and the second station STA2 sets the OBO counter to 0. Since the OBO counter of the second station STA2 becomes 0, the second station STA2 randomly selects any one of the first RU RU 1 and the second RU RU 2 allocated for random access and attempts to transmit. After the SIFS from when the second station STA2 receives the trigger frame, the second station STA2 sends a TB PPDU to the AP through the randomly selected RU. The AP receives the TB PPDU from the second station STA2. After the SIFS from receiving the TB PPDU from the AP, the AP sends the ACK of the frame sent by the second station to the second station.

[0118] The second station STA2 whose transmission by the AP is successful sets the OCW to OCWmin and selects an arbitrary number within the set OCW. In this case, the second station STA2 selects 6 and sets 6 as the OBO counter. The AP sends a trigger frame that triggers the random access of the first RU RU 1, the second RU RU 2, and the third RU RU 3. Since the number of RUs allocated for random access is 3, the first station STA1 decrements the OBO counter by 3 and sets it to 0, and the second station STA2 decrements the OBO counter by 3 and sets it to 3. Since the OBO counter of the first station STA1 becomes 0, the first station STA1 arbitrarily selects any one of the first RU RU1, the second RU RU 2, and the third RU RU 3, allocates a trigger for random access therein, and attempts to transmit. After the SIFS from when the first station STA1 receives the trigger frame, the first station STA1 sends a TBPPDU to the AP through the arbitrarily selected RU. The AP receives the TB PPDU from the first station STA1. After the SIFS from receiving the TB PPDU from the AP, the AP sends the ACK of the frame sent by the first station to the first station.

[0119] As described above, the wireless communication terminal can set OCWmin and OCWmax according to the OBO-related parameter value signaled by the base station associated with the wireless communication terminal. Specifically, the wireless communication terminal can receive an element including the OBO-related parameter value from the base station associated with the wireless communication terminal. In this case, this element can be referred to as a UL OFDMA-based random access (UORA) parameter set element. With reference toFigure 10 Describe a specific format of UORA parameter set elements.

[0120] Figure 10 Illustrate a specific format of UORA parameter set elements according to an embodiment of the present invention.

[0121] A UORA parameter set element may include an element ID field, a length field, an element ID extension field, and an OCW range field. The element ID field indicates an element identifier that identifies the UORA parameter set element. The length field indicates the length of the UORA element. The element ID extension field indicates an extended ID that combines with the element ID to generate an extended ID of the UORA parameter set element. The OCW range field indicates information about the OCW range.

[0122] The OCW range field may include information about OCWmin and OCWmax. Specifically, the OCW range field may include an EOCWmin field, an EOCWmax field, and a reserved field. In this case, the wireless communication terminal may set OCWmin according to the value indicated by the EOCWmin field. In a specific embodiment, the wireless communication terminal may set OCWmin to 2 EOCWmin -1. In addition, the wireless communication terminal may set OCWmax according to the value indicated by the EOCWmax field. In a specific embodiment, the wireless communication terminal may set OCWmax to 2 EOCWmax -1.

[0123] The wireless communication terminal may set OCWmin and OCWmax according to the most recently received UORA parameter set element. Additionally, the wireless communication terminal may set OCWmin and OCWmax according to the most recently received UORA parameter set element regardless of the access category (AC) of the traffic to be transmitted. The base station wireless communication terminal may use a beacon frame to transmit the UORA parameter set element. In addition, the base station wireless communication terminal may use a probe response frame to transmit the UORA parameter set element.

[0124] The specific format of the UORA parameter set element may be the same as Figure 10 the format in.

[0125] When there are multiple physical access points in a network, due to management frames sent by multiple access points, the time for frames used for data transmission to occupy the channel may be very short. Therefore, a base station wireless communication terminal is capable of operating multiple BSSs in the network. This will be described with reference to Figure 11 this.

[0126] Figure 11 Illustrate a specific format of multiple BSSID elements according to an embodiment of the present invention.

[0127] A base station wireless communication terminal may send a management frame to signal information about multiple BSSs. Specifically, the base station wireless communication terminal sends a management frame to signal information about each BSS corresponding to a plurality of Basic Service Set Identifiers (BSSIDs) included in a multi-BSSID set. The multi-BSSID set is a set of BSSIDs corresponding to each of a plurality of BSSs classified as a group. When the base station wireless communication terminal uses the multi-BSSID set, since the wireless communication terminal sends a management frame and sends information about multiple BSSs, the amount of time that a data frame can occupy the channel may increase. In a particular embodiment, the wireless communication terminal may set a reference BSSID representing the multi-BSSID set as the BSS information indicated by the management frame and insert information about the multi-BSSID set into the management frame. The information about the multi-BSSID set may include information related to the maximum number of BSSIDs included in the multi-BSSID set. In this case, the reference BSSID may be the BSSID used as a reference when identifying the BSSIDs included in the multi-BSSID set. Specifically, the information about the multi-BSSID set may be Figure 11 the multiple BSSID elements in. In this case, the information about the multi-BSSID set may include sub-elements.

[0128] The multiple BSSID elements may include an Element ID field. The Element ID field is an identifier indicating the multiple BSSID elements. Additionally, the multiple BSSID elements may include a Length field. The Length field is a field indicating the length of the multiple BSSID elements. Additionally, the multiple BSSID elements may indicate a Maximum BSSID Indicator field. In this case, the Maximum BSSID Indicator field may indicate information related to the maximum number of BSSIDs that the multi-BSSID set may include. Specifically, when the value indicated by the Maximum BSSID Indicator field is n, the maximum number of BSSIDs that the multi-BSSID set may include is 2 n . In this case, the maximum number of BSSIDs is the number including the reference BSSID.

[0129] Additionally, the multiple BSSID elements may include an optional Sub-Element field. The optional sub-elements may include information about the BSS indicated by an Unsent BSSID. Except for the reference BSSID, the Unsent BSSIDs indicate the BSSIDs included in the multi-BSSID set. Specifically, the optional Sub-Element field may include an Unsent BSSID Profile, which is information about the BSS indicated by an Unsent BSSID. The optional Sub-Element field may include only information about the BSSs indicated by some of the Unsent BSSIDs. In this case, the wireless communication terminal may obtain information about the BSSs indicated by the remaining Unsent BSSIDs based on a beacon frame or a probe response frame.

[0130] The information about the BSS indicated by the unsent BSSID can be an element to be included in the unsent BSSID capability element and the beacon frame body. Specifically, the element that can be included in the beacon frame body can be at least one of the SSID, the multi-BSSID index sub-element, and the FMD descriptor element. Additionally, the information identical to the BSS information indicated by the reference BSSID in the information about the BSS indicating the unsent BSSID can be omitted. Specifically, at least one of the timestamp and the beacon interval fields indicated by the non-transmitted BSSID, DSSS parameter set, IBSS parameter set, country, channel switch announcement, extended channel switch announcement, wideband channel switch, transmit power envelope, supported operation class, IBSS DFS, ERP information, HT capability, HT operation, VHT capability, and VHT operation elements can be the same as the BSS indicated by the reference BSSID.

[0131] In addition, the optional sub-element field can include vendor-specific elements.

[0132] A wireless communication terminal that receives a management frame including information about a multi-BSSID set can obtain the information about the multi-BSSID set from the management frame. In this case, the wireless communication terminal can obtain the BSSIDs included in the multi-BSSID set based on the information about the multi-BSSID set and the reference BSSID. Specifically, the wireless communication terminal can obtain the BSSIDs included in the multi-BSSID set through the following equation.

[0133] BSSID(i) = BSSID_A | BSSID_B

[0134] In this case, BSSID_A is the BSSID where the (48 - n) most significant bit (MSB) values are equal to the (48 - n) MSB values of the reference BSSID, and the n least significant bit (LSB) values are 0. Additionally, BSSID_B is the BSSID where the (48 - n) MSB values are 0, and the n LSB values are the remainder (mod) when dividing the sum of the n LSBs and i of the reference BSSID by 2 n is taken.

[0135] In addition, a base station wireless communication terminal may signal information about a multi-BSSID set using an operating element. The operating element may include a MaxBSSID indicator field and a Tx BSSID indicator field. The MaxBSSID indicator field may indicate the same information as the maximum BSSID indicator field of the multiple BSSID elements. Thus, in the same manner as the method of obtaining the BSSID of the BSS in which a management frame is transmitted using the MAX BSSID indicator field of the multi-BSSID element, the wireless communication terminal may obtain the BSSID of the BSS in which a management frame is transmitted by using the MaxBSSID indicator field. The Tx BSSID indicator field indicates whether the BSS to which an association frame including the operating element is transmitted corresponds to an untransmitted BSSID. Specifically, when the Tx BSSID indicator field is 1, the BSS in which a management frame including the operating element is transmitted corresponds to the transmitted BSSID. When the Tx BSSID indicator field is 0, the BSS in which a management frame including the operating element is transmitted corresponds to an untransmitted BSSID.

[0136] In addition, a wireless communication terminal may signal information about capabilities related to a multi-BSSID set using a capabilities element of a management frame. Specifically, the wireless communication terminal may use the capabilities element of the management frame to send an Rx control frame field to MultiBSS. When the wireless communication terminal is associated with a BSS corresponding to an untransmitted BSSID, the Rx control frame field to MultiBSS may indicate whether frames transmitted from the transmitted BSSID can be received. Specifically, the Rx control frame field to MultiBSS may indicate whether control frames transmitted from the transmitted BSSID can be received when the wireless communication terminal is associated with a BSS corresponding to an untransmitted BSSID.

[0137] When the BSS including the wireless communication terminal corresponds to a multi-BSSID set, the OFDMA random access operation of the wireless communication terminal is a problem. The reason is that the BSSs included in the multi-BSSID set are formally different BSSs, but due to the purpose of using the multi-BSSID set, in the operation of a specific wireless communication terminal, the BSSs included in the multi-BSSID set may be regarded as the same BSS (within the BSS). Moreover, the reason is that a trigger frame transmitted from the transmitted BSSID can trigger the uplink transmission of the wireless communication terminal included in the BSS corresponding to the untransmitted BSSID. Specifically, there are problems related to OBO-related parameter settings, OBO process initialization, OBO counter decrement operation, and RU selection for random access in the operation of the wireless communication terminal.

[0138] When the BSS of a wireless communication terminal is included in a multi - BSSID set and the wireless communication terminal is associated with a BSS corresponding to an unsent BSSID, the wireless communication terminal can set OBO - related parameters based on the UORA parameter set sent by the sent BSSID. When the BSS of a wireless communication terminal is included in a multi - BSSID set and the wireless communication terminal is associated with a BSS corresponding to an unsent BSSID, the wireless communication terminal can update OCWmin and OCWmax according to the UORA parameter set sent by the sent BSSID. In this embodiment, the UORA parameter set may not be included in the unsent BSSID profile. Additionally, the UORA parameter set can be commonly applied to at least one other BSS included in the multi - BSSID set. Therefore, when the BSS of a wireless communication terminal is included in a multi - BSSID set and the wireless communication terminal is associated with a BSS corresponding to an unsent BSSID, the wireless communication terminal can set OBO - related parameters according to the UORA parameter set sent by the sent BSSID. Additionally, when the BSS of a wireless communication terminal is included in a multi - BSSID set and the wireless communication terminal is associated with a BSS corresponding to an unsent BSSID, the unsent BSSID profile sub - element corresponding to the BSS associated with the wireless communication terminal may not include a UORA parameter set element. In this way, when the unsent BSSID profile sub - element does not include a UORA parameter set element, the wireless communication terminal can set OBO - related parameters according to the UORA parameter set sent by the sent BSSID.

[0139] When a base - station wireless communication terminal sends a management frame in a BSS corresponding to the sent BSSID, the base - station wireless communication terminal can signal OBO - related parameters using the UORA parameter set sent by the sent BSSID for use by wireless communication terminals in multiple BSSs corresponding to the multi - BSSID set. Further, when a base - station wireless communication terminal sends a management frame in a BSS corresponding to the sent BSSID, the base - station wireless communication terminal can use the unsent BSSID profile sub - element to signal OBO - related parameters separated from other BSSs of the multi - BSSID set to the wireless communication terminal corresponding to the unsent BSSID. Through these embodiments, the base - station wireless communication terminal can effectively signal OBO - related parameters to multiple wireless communication terminals included in the BSSs corresponding to the multi - BSSID set.

[0140] As described above, when a wireless communication terminal transmits information about OBO-related parameters from the base station to the wireless communication terminal by a signal, the wireless communication terminal may initialize the OBO process. Therefore, if the BSS of the wireless communication terminal is included in a multi-BSSID set and the wireless communication terminal is associated with a BSS corresponding to an untransmitted BSSID, when the wireless communication terminal receives a set of UORA parameters transmitted by the transmitted BSSID, the wireless communication terminal may initialize the OBO process. If the BSS of the wireless communication terminal is included in a multi-BSSID set and the wireless communication terminal is associated with a BSS corresponding to an untransmitted BSSID, when the wireless communication terminal receives a set of UORA parameters transmitted by the transmitted BSSID, the wireless communication terminal may initiate the OBO process. In addition, when the BSS of the wireless communication terminal is included in a multi-BSSID set and the wireless communication terminal is associated with a BSS corresponding to an untransmitted BSSID, the untransmitted BSSID profile sub-element corresponding to the BSS associated with the wireless communication terminal may not include a UORA parameter set element. In this case, the wireless communication terminal may initiate the OBO process. In a particular embodiment, when the wireless communication terminal initiates the OBO process, the wireless communication terminal may set the OCW to OCWmin and randomly select an OBO counter within the OCW.

[0141] If the transmitter address TA of the trigger frame is the BSSID of the associated BSS, the wireless communication terminal may decrement the OBO counter based on the RU indicated by the trigger frame. Therefore, even when the BSS of the wireless communication terminal is included in a multi-BSSID set, when the transmitter address TA of the trigger frame is the BSSID of the BSS associated with the wireless communication terminal, the wireless communication terminal can decrement the OBO counter based on the RU indicated by the trigger frame. Specifically, when the BSS of the wireless communication terminal is included in a multi-BSSID set and the transmitter address of the trigger frame is the transmitted BSSID, the wireless communication terminal associated with the BSS having the untransmitted BSSID may not decrement based on the RU indicated by the corresponding trigger frame. In addition, when the BSS of the wireless communication terminal is included in a multi-BSSID set and the transmitter address of the trigger frame is the untransmitted BSSID, the wireless communication terminal associated with the BSS having the transmitted BSSID may not decrement based on the RU indicated by the corresponding trigger frame.

[0142] In another specific embodiment, when the transmitter address of the trigger frame is the transmitted BSSID, a wireless communication terminal associated with a BSS having an untransmitted BSSID may be allowed to decrement the OBO counter based on the trigger frame. However, in this embodiment, fairness of a wireless communication terminal associated with a BSS having a transmitted BSSID may be a problem. In addition, when the receiver address of the trigger frame is a BSSID included in a multi-BSSID set, a wireless communication terminal associated with a BSS included in the multi-BSSID set may be allowed to decrement the OBO counter based on the trigger frame. In this embodiment, since a wireless communication terminal associated with a BSS corresponding to the transmitted BSSID may decrement the OBO counter based on a trigger frame that cannot trigger the wireless communication terminal, fairness of a random access operation of a wireless communication terminal not associated with a BSS corresponding to the multi-BSSID set may be a problem. Moreover, even when the transmitter address of the trigger frame is the transmitted BSSID and the trigger frame triggers a transmission to a wireless communication terminal associated with an untransmitted BSSID, a wireless communication terminal associated with the BSSID may be allowed to decrement the OBO counter based on the trigger frame. To confirm whether a trigger frame whose transmitted address is the transmitted BSSID triggers a transmission to a wireless communication terminal associated with an untransmitted BSSID, a wireless communication terminal may be required to decode a user information field. Therefore, this embodiment may increase the complexity of the random access operation of the wireless communication terminal.

[0143] Reference will be made to Figure 12 specific operations of a wireless communication terminal related to OBO-related parameter setting, OBO process initialization, OBO counter decrement operation, and RU selection for random access will be described in detail.

[0144] Figures 12 to 13 FIG. shows a random access operation of a wireless communication terminal associated with a multi-BSSID set according to an embodiment of the present invention.

[0145] In Figure 12 's embodiment, a first station STA1 is associated with a BSS corresponding to a transmitted BSSID of a multi-BSSID set. A second station STA2 is associated with a BSS corresponding to an untransmitted BSSID of the multi-BSSID set. The first station STA1 and the second station STA2 receive a beacon frame transmitted from the transmitted BSSID. In this case, the first station STA1 and the second station STA2 update OCWmin and OCWmax according to a UORA parameter set element included in the beacon frame. In a specific embodiment, since the UORA parameter set of the beacon frame is announced by the transmitted BSSID and is not included in an untransmitted BSSID profile sub-element, the second station STA2 may update OCWmin and OCWmax according to the UORA parameter set element.

[0146] In addition, since the first station STA1 and the second station STA2 receive information about OBO-related parameters from the base station wireless communication terminal, the first station STA1 and the second station STA2 initialize the OBO process. Specifically, the first station STA1 and the second station STA2 randomly select an OBO counter within the OCW. The first station STA1 selects 3, and the second station STA2 selects 5.

[0147] The first station STA1 and the second station STA2 receive a trigger frame having the transmitted BSSID as the transmitter address TA. In this case, the trigger frame indicates that two RUs are allocated for random access. In Figure 12 the embodiment, it is assumed that a wireless communication terminal associated with a BSS included in a multi-BSSID set can decrement the OBO counter based on a trigger frame having a BSSID included in the plurality of BSSIDs set as the transmitter address. Therefore, the first station STA1 sets the OBO counter to 1 by decrementing the OBO counter by 2 according to the trigger frame, and the second station STA2 associated with the BSS corresponding to the non-transmitted BSSID decrements the OBO counter by 2 according to the trigger frame and sets the OBO counter to 3.

[0148] The first station STA1 and the second station STA2 receive a trigger frame having the non-transmitted BSSID as the transmitter address TA. In this case, the trigger frame indicates that two RUs are allocated for random access. The first station STA1 decrements the OBO counter by 2 according to the trigger frame to set the OBO counter to 0 and randomly selects one of the two RUs indicated by the trigger frame to be allocated for random access and attempts to perform a transmission. The second station STA2 associated with the BSS corresponding to the non-transmitted BSSID decrements the OBO counter by 2 according to the trigger frame to set the OBO counter to 1.

[0149] If the first station STA1 and the second station STA2 receive a beacon frame that does not include UORA parameter set elements, the first station STA1 and the second station STA2 maintain the existing OBO process. The first station STA1 and the second station STA2 receive a beacon frame sent from the transmitted BSSID. In this case, the beacon frame includes UORA parameter set elements. Therefore, the first station STA1 and the second station STA2 update OCWmin and OCWmax according to the UORA parameter set elements included in the beacon frame and initialize the OBO process.

[0150] Refer to Figure 12 The described OBO counter decrement operation can complicate the random access operation of the wireless communication terminal as described above and may cause fairness issues with other wireless communication terminals. Therefore, as Figure 13As shown, even when the BSS of a wireless communication terminal is included in a multi-BSSID set, when the transmitter address TA of a trigger frame is the BSSID of the BSS associated with the wireless communication terminal, the wireless communication terminal can decrement the OBO counter based on the RU indicated by the trigger frame.

[0151] In Figure 13 the embodiment of, descriptions of operations and situations the same as those of Figure 12 the embodiment will be omitted. The first station STA1 and the second station STA2 receive a trigger frame with the transmitted BSSID as the transmitter address TA. In this case, the trigger frame indicates that two RUs are allocated for random access. The first station STA1 associated with the BSS corresponding to the transmitted BSSID decrements the OBO counter by 2 to set the OBO counter to 1. Since the second station STA2 is associated with the BSS corresponding to the non-transmitted BSSID, the second station STA2 maintains the OBO counter at 5.

[0152] In addition, the first station STA1 and the second station STA2 receive a trigger frame with the non-transmitted BSSID as the transmitter address TA. In this case, the trigger frame indicates that two RUs are allocated for random access. Since the first station STA1 is associated with the BSS corresponding to the transmitted BSSID, the first station STA1 maintains the OBO counter at 1. The second station STA2 associated with the BSS corresponding to the non-transmitted BSSID decrements the OBO counter by 2 to set the OBO counter to 3.

[0153] Even when a trigger frame triggers random access, when the capability of a wireless communication terminal does not support the uplink transmission conditions indicated by the trigger frame, even if the OBO counter reaches 0, the wireless communication terminal cannot randomly perform access. For example, when a wireless communication terminal does not support the transmission of the frequency bandwidth of an RU (indicated as the RU allocated for random access), the corresponding wireless communication terminal cannot perform random access to the corresponding RU. Therefore, a random access operation that takes into account the capabilities of the wireless communication terminal is required.

[0154] When a wireless communication terminal receives a trigger frame, the wireless communication terminal can decrement the OBO counter according to the capabilities of the wireless communication terminal. Specifically, when the wireless communication terminal receives a trigger frame, the wireless communication terminal can decrement the OBO counter based on the RU allocated for random access and the capabilities of the wireless communication terminal. In a particular embodiment, the wireless communication terminal can decrement the OBO counter by the number of RUs among those allocated for random access through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal. As described above, the RU allocated for random access can be indicated by the trigger frame. Additionally, the wireless communication terminal can determine whether it can transmit a TB PPDU through an RU based on the transmission conditions indicated by the trigger frame.

[0155] Furthermore, when the OBO counter reaches 0, the wireless communication terminal can select an RU according to the capabilities of the wireless communication terminal. In a specific embodiment, when the OBO counter reaches 0, the wireless communication terminal can randomly select any one of the RUs allocated for random access and through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal.

[0156] When the OBO counter reaches 0, the wireless communication terminal can postpone random access and maintain the OBO counter. Specifically, when there is no buffered data in the wireless communication terminal corresponding to the response length indicated by the trigger frame, the wireless communication terminal can postpone random access and maintain the OBO counter at 0. In this case, the wireless communication terminal can perform random access in response to the next trigger frame that triggers random access. Additionally, if there is no RU among those allocated for random access through which the wireless communication terminal can transmit a TB PPDU according to the capabilities of the wireless communication terminal, the wireless communication terminal can maintain the OBO counter at 0. In this case, the wireless communication terminal can perform random access in response to the next trigger frame that triggers random access.

[0157] Furthermore, the capabilities of the wireless communication terminal can include the capabilities of the wireless communication terminal that are related to at least one of the bandwidth supported for transmission, modulation and coding scheme (MCS), dual carrier modulation (DCM), number of spatial streams, length of the guard interval (GI), long training field (LTF) type, space-time block coding (STBC), transmission power, and length of the padding field. The length of the padding field can indicate the length of the padding field included in the TB PPDU. Specific operations of the wireless communication terminal will be described with reference to Figures 14 to 21 the specific operations of the wireless communication terminal.

[0158] Figure 14 Illustrates the types of RUs and subcarrier indices that can be used when transmitting a PPDU with a transmission bandwidth of 20 MHz according to an embodiment of the present invention. Figure 15Shows the types of RUs and subcarrier indices that can be used when transmitting a PPDU with a transmission bandwidth of 40 MHz according to an embodiment of the present invention. Figure 16 Shows the types of RUs and subcarrier indices that can be used when transmitting a PPDU with a bandwidth of 80 MHz according to an embodiment of the present invention.

[0159] As described above, an RU can indicate that a plurality of subcarriers available for uplink and downlink transmission can be grouped according to the size of the frequency band.

[0160] A wireless communication terminal according to an embodiment of the present invention can perform uplink transmission or downlink transmission using at least one of an RU using 26 subcarriers (26-tone RU), an RU using 52 subcarriers (52-tone RU), an RU using 106 subcarriers (106-tone RU), an RU using 242 subcarriers (242-tone RU), an RU using 484 subcarriers (484-tone RU), an RU using 996 subcarriers (996-tone RU), and an RU using 1992 subcarriers (2*996-tone RU). Specifically, the wireless communication terminal can transmit a HE MU PPDU or a HE-triggered PPDU through OFDMA using a specified RU. In this case, when the frequency bandwidth of the PPDU is any one of 20 MHz, 40 MHz, 80 MHz, 160 MHz, and 80+80 MHz, the wireless communication terminal can use any one of the 26-tone RU, 52-tone RU, 106-tone RU, and 242-tone RU to transmit the PPDU. Additionally, when the frequency bandwidth of the PPDU is any one of 40 MHz, 80 MHz, 160 MHz, and 80+80 MHz, the wireless communication terminal can use the 484-tone RU to transmit the PPDU. Additionally, when the frequency bandwidth of the PPDU is any one of 80 MHz, 160 MHz, and 80+80 MHz, the wireless communication terminal can use the 996-tone RU. Additionally, when the frequency bandwidth of the PPDU is any one of 160 MHz and 80+80 MHz, the wireless communication terminal can use the 2*996-tone RU to transmit the PPDU.

[0161] In addition, the wireless communication terminal can send a HE single-user (SU) PPDU using a specified RU. In this case, if the frequency bandwidth of the HE SU PPDU is 20 MHz, the wireless communication terminal can use a 242-tone RU to send the HE SU PPDU. In addition, if the frequency bandwidth of the HE SU PPDU is 40 MHz, the wireless communication terminal can use a 484-tone RU to send the HE SU PPDU. In addition, if the frequency bandwidth of the HE SU PPDU is 80 MHz, the wireless communication terminal can use a 996-tone RU to send the HE SU PPDU. In addition, if the frequency bandwidth of the HE SU PPDU is 160 MHz or 80 + 80 MHz, the wireless communication terminal can use 2 * 996-tone RUs to send the HE SU PPDU.

[0162] The 26-tone RU may include 24 subcarriers for sending data and 2 subcarriers for sending pilot signals. The specific position of the 26-tone RU may be the same as that shown in Figure 14 , Figure 15 and Figure 16 . When the frequency bandwidth of the PPDU sent by the wireless communication terminal is a PPDU of 160 MHz or 80 + 80 MHz, the 26-tone RUs sent through each 80-MHz band may be the same as those shown in Figure 15 . The 52-tone RU may include 48 subcarriers for sending data and 4 subcarriers for sending pilot signals. The specific position of the 52-tone RU may be the same as that shown in Figure 14 , Figure 15 and Figure 16 . When the frequency bandwidth of the PPDU sent by the wireless communication terminal is a PPDU of 160 MHz or 80 + 80 MHz, the 52-tone RUs sent through each 80-MHz band may be the same as those shown in Figure 15 .

[0163] The 106-tone RU may include 102 subcarriers for sending data and 4 subcarriers for sending pilot signals. The specific position of the 106-tone RU may be the same as that shown in Figure 14 , Figure 15 and Figure 16 . When the frequency bandwidth of the PPDU sent by the wireless communication terminal uses a PPDU of 160 MHz or 80 + 80 MHz, the 106-tone RUs sent through each 80-MHz band may be the same as those shown in Figure 15 . The 242-tone RU may include 234 subcarriers for sending data and 8 subcarriers for sending pilot signals. The specific position of the 242-tone RU may be the same as that shown in Figure 14 , Figure 15 and Figure 16The same as that shown in. When the frequency bandwidth of the PPDU sent by the wireless communication terminal is 160 MHz or an 80 + 80 MHz PPDU, the 242 - tone RUs sent through each 80 - MHz band can be the same as those Figure 15 shown in.

[0164] The 484 - tone RU can include 468 sub - carriers for sending data and 16 sub - carriers for sending pilot signals. The specific position of the 484 - tone RU can be the same as that Figure 15 and Figure 16 shown in. When the frequency bandwidth of the PPDU sent by the wireless communication terminal is 160 MHz or an 80 + 80 MHz PPDU, the 484 - tone RUs sent through each 80 - MHz band can be the same as those Figure 15 shown in. The 996 - tone RU can include 980 sub - carriers for sending data and 16 sub - carriers for sending pilot signals. The specific position of the 996 - tone RU can be the same as that Figure 15 shown in. When the frequency bandwidth of the PPDU sent by the wireless communication terminal is 160 MHz or an 80 + 80 MHz PPDU, the 996 - tone RUs sent through each 80 - MHz band can be the same as those Figure 15 shown. When the wireless communication terminal sends a PPDU with a bandwidth of 160 MHz or 80 + 80 MHz, the sub - carriers included in the 996 - tone RU are located at [-1012:-515, -509:-12] and [12:509, 515:1012]. In this case, [x:y] represents the sub - carrier indices from x to y. Therefore, even when using 2 * 996 - tone RUs, the wireless communication terminal uses the sub - carriers with sub - carrier indices located at [-1012:-515, -509:-12] and [12:509, 515:1012].

[0165] If a wireless communication terminal transmits a HE MU PPDU or a HE trigger-based PPDU having a frequency bandwidth of 20 MHz and the PPDU includes two or more RUs, the wireless communication terminal may transmit seven direct current (DC) subcarriers at [-3:3]. When the wireless communication terminal transmits a HE SU PPDU having a frequency bandwidth of 20 MHz using a 242-tone RU, the wireless communication terminal may transmit three DC subcarriers at [-1:1]. When the wireless communication terminal transmits a HE SU PPDU having a frequency bandwidth of 40 MHz using a 484-tone RU, the wireless communication terminal may transmit five DC subcarriers at [-2:2]. If a wireless communication terminal transmits a HE MU PPDU or a HE trigger-based PPDU having a frequency bandwidth of 80 MHz and the PPDU includes two or more RUs, the wireless communication terminal may transmit seven DC subcarriers at [-3:3]. When the wireless communication terminal transmits a HE SU PPDU having a frequency bandwidth of 80 MHz using a 996-tone RU, the wireless communication terminal may transmit five DC subcarriers at [-2:2]. When the wireless communication terminal transmits a PPDU having a bandwidth of 160 MHz or 80+80 MHz, the wireless communication terminal may use a 996-tone RU to transmit the DC subcarriers to the same positions as in the case of transmitting a HE SU PPDU having a frequency bandwidth of 80.

[0166] When the wireless communication terminal transmits a PPDU having a frequency bandwidth of 20 MHz, the wireless communication terminal may transmit 11 guard subcarriers to [-128:-123] and [123:127]. When the wireless communication terminal transmits a PPDU having a frequency bandwidth of 40 MHz, the wireless communication terminal may transmit 23 guard subcarriers to [-256:-245] and [245:255]. When the wireless communication terminal transmits a PPDU having a frequency bandwidth of 80 MHz, the wireless communication terminal is capable of transmitting 23 guard subcarriers to [-512:-501] and [501:511]. When the wireless communication terminal transmits a PPDU having a frequency bandwidth of 160 MHz or 80+80 MHz, the wireless communication terminal may transmit the guard subcarriers for transmitting a PPDU having a frequency bandwidth of 80 MHz to both ends.

[0167] Figure 17 Shows the coding values of the RUs in the RU allocation subfield for indicating a trigger frame according to an embodiment of the present invention.

[0168] The RU allocation subfield indicates the RU to be used for transmission by a wireless communication terminal triggered by a trigger frame. The RU allocation subfield can be an 8-bit field. In this case, one bit of the RU allocation subfield, for example, B12, can indicate whether the RU indicated by the RU allocation subfield is in the primary 80 MHz channel or a non-primary 80 MHz channel. The primary channel represents the frequency band that is the basis for frequency band expansion. Moreover, the primary channel can refer to a continuous frequency band that includes a frequency band with a 20 MHz frequency bandwidth, which is the basis for frequency band expansion. In addition, when the RU has a frequency bandwidth of 80 MHz or less, 7 bits of the RU allocation subfield, for example, B19 - B13, indicate which RU is indicated within 80 MHz. In addition, when the RU has a frequency bandwidth equal to or greater than 80 MHz, 7 bits of the RU allocation subfield, for example, B19 - B13, indicate which RU is indicated within a frequency bandwidth equal to or greater than 80 MHz. The specific values of the RU allocation field can be the same as those in Figure 17 the same.

[0169] Specifically, in the case where the PPDU has a frequency bandwidth of 20 MHz, 40 MHz, or 80 MHz, B12 can be set to 0. In addition, in the case of a 2 * 996-tone RU, B12 can be set to 1. Additionally, B19 - B13 can also be set as follows.

[0170] - When the wireless communication terminal transmits a PPDU with a 20 MHz frequency bandwidth, the wireless communication terminal can specify the Figure 14 RU index in ascending order in B19 - B13. When the value of B19 - B13 is 0000000, the RU allocation subfield can indicate 26-tone RU 1. When the value of B19 - B13 is 0001000, the RU allocation subfield can indicate 26-tone RU 9. The values of B19 - B13 may not use 0001001 to 0100100. When the value of B19 - B13 is 0100101, the RU allocation subfield can indicate 52-tone RU 1. When the value of B19 - B13 is 0101000, the RU allocation subfield can indicate 52-tone RU 4. The values of B19 - B13 may not use 0101001 to 0110100. When the value of B19 - B13 is 0110101, the RU allocation subfield can indicate 106-tone RU1. When the value of B19 - B13 is 0110110, the RU allocation subfield can indicate 106-tone RU 2. The values of B19 - B13 may not use 0110111 to 0111100. When the value of B19 - B13 is 0111101, the RU allocation subfield can indicate 242-tone RU1. The values of B19 - B13 may not use 0111110 to 1000000.

[0171] - When the wireless communication terminal transmits a PPDU with a 40 MHz frequency bandwidth, the wireless communication terminal may specify, in ascending order, the RU index in B19 - B13. Figure 15 When the value of B19 - B13 is 0000000, the RU allocation subfield may indicate 26 - tone RU1. When the value of B19 - B13 is 0010001, the RU allocation subfield may indicate 26 - tone RU18. The values of B19 - B13 may not use 0010010 to 0100100. When the value of B19 - B13 is 0100101, the RU allocation subfield may indicate 52 - tone RU1. When the value of B19 - B13 is 0101100, the RU allocation subfield may indicate 52 - tone RU8. The values of B19 - B13 may not use 0101101 to 0110100. The values of B19 - B13 may be specified for 106 - tone, 242 - tone, and 484 - tone RUs according to rules such as 26 - tone RUs and 52 - tone RUs.

[0172] - When the wireless communication terminal transmits a PPDU with frequency bandwidths of 80 MHz, 160 MHz, and 80 + 80 MHz, the wireless communication terminal may specify, in ascending order, the RU index in B19 - B13. Figure 12 When the value of B19 - B13 is 0000000, the RU allocation subfield may indicate 26 - tone RU1. When the value of B19 - B13 is 0100100, the RU allocation subfield may indicate 26 - tone RU37. When the value of B19 - B13 is 0100101, the RU allocation subfield may indicate 52 - tone RU1. If the value of B19 - B13 is 0110100, the value of the RU allocation subfield may indicate 52 - tone RU16. The values of B19 - B13 may be specified for 106 - tone, 242 - tone, 484 - tone, and 996 - tone RUs according to rules such as 26 - tone RUs and 52 - tone RUs. When the wireless communication terminal transmits a 160 MHz or 80 + 80 MHz PPDU and the value of B19 - B13 is 1000100, the RU allocation subfield may indicate 2 * 996 - tone RU.

[0173] The wireless communication terminal is capable of supporting the transmission and reception of PPDUs with a frequency bandwidth equal to or narrower than a specific size. For example, the wireless communication terminal may only support the transmission and reception of PPDUs with a bandwidth of 20 MHz. Additionally, the wireless communication terminal may support the transmission and reception of PPDUs with a frequency bandwidth of 80 MHz or less. In this way, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than a specific size, the wireless communication terminal can decrement the OBO counter based on the number of RUs included in the frequency bandwidth equal to or narrower than the specific size among the RUs allocated for random access. In this case, the RUs allocated for random access can be indicated by a trigger frame. Furthermore, the wireless communication terminal decrements the OBO counter when it receives the trigger frame. Specifically, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than a specific size, the wireless communication terminal can reduce the OBO counter based on the number of RUs included in the primary channel with a frequency bandwidth equal to or narrower than the specific size among the RUs allocated for random access. The wireless communication terminal may not support non-primary channels because it is difficult to switch channels within a specific time. In this case, the non-primary channel can refer to a channel other than the primary channel. For example, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than 20 MHz, the wireless communication terminal can decrement the OBO counter based on the number of RUs among those allocated for random access where the B19 - B13 value of the RU allocation subfield is from 0000000 to 0001000 or 0100101 to 0101000 or 0110101 to 0110110 or 0111101. In another specific embodiment, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than a specific size, the wireless communication terminal can decrement the OBO counter based on the number of RUs included in the frequency bandwidth equal to or narrower than the specific size among the RUs allocated for random access, regardless of whether the RUs are included in the primary channel. For example, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than 20 MHz or less, the wireless communication terminal can decrement the OBO counter based on the number of RUs among those allocated for random access where the B19 - B13 value of the RU allocation subfield is less than or equal to 1000000.

[0174] In addition, when the OBO counter reaches 0 and the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than a specific size, the wireless communication terminal can randomly select any one of the RUs allocated for random access and included in a frequency bandwidth equal to or less than the specific size. In this case, the wireless communication terminal can attempt to transmit through the selected RU. The RU allocated for random access can be indicated by the trigger frame as described above. When there is no frequency bandwidth equal to or narrower than the specific size in the RU allocated for random access, the wireless communication terminal can maintain the OBO counter without attempting to transmit. In this case, the wireless communication terminal can attempt random access in response to the next trigger frame sent. In this embodiment, when the wireless communication terminal decrements the OBO counter, the wireless communication terminal can ignore the capabilities of the wireless communication terminal. Specifically, when the wireless communication terminal decrements the OBO counter regardless of whether the RU is included in a frequency bandwidth equal to or less than the specific size, when the OBO counter reaches 0, the wireless communication terminal can randomly select any one of the RUs allocated for random access and included in a frequency bandwidth equal to or less than the specific size.

[0175] In addition, in a specific embodiment, the wireless communication terminal can randomly select any one of the RUs allocated for random access and the RUs included in a primary channel with a bandwidth equal to or narrower than a specific size. The wireless communication terminal may not support non-primary channels because it is difficult to switch channels within a specific time. For example, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than 20 MHz, the wireless communication terminal can arbitrarily select any one of the RUs allocated for random access and the RUs in which the B19 - B13 values of the RU allocation subfield corresponding to the respective RUs are from 0000000 to 0001000 or 0100101 to 0101000 or 0110101 to 0110110 or 0111101. In another specific embodiment, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or narrower than a specific size, the wireless communication terminal can randomly select any one of the RUs allocated for random access, regardless of whether the RU is included in the primary channel and included in a frequency bandwidth equal to or less than the specific size. For example, when the wireless communication terminal only supports the transmission and reception of PPDUs with a frequency bandwidth equal to or less than 20 MHz, the wireless communication terminal can arbitrarily select any one of the RUs allocated for random access in which the value of B19 - B13 of the RU allocation subfield corresponding to the respective RU is 1000000 or less.

[0176] Figures 18 to 19 An operation in which a wireless communication terminal that only supports PPDUs with a bandwidth of 20 MHz performs random access according to an embodiment of the present invention is shown.

[0177] InFigures 18 to 21 In an embodiment, the wireless communication terminal decrements an OBO counter based on the frequency bandwidth supported by the wireless communication terminal. In Figure 18 and Figure 20 In an embodiment, when the RU allocated for random access is included in a primary channel whose frequency bandwidth is equal to or narrower than a specific size, the wireless communication terminal decrements the OBO counter based on the corresponding RU.

[0178] In Figure 18 In an embodiment, the first station STA1 only supports a frequency band equal to or narrower than 20 MHz. The second station STA2 supports a frequency band equal to or wider than 20 MHz. The first station STA1 and the second station STA2 receive a beacon frame from the first AP AP1. The first station STA1 and the second station STA2 obtain a UORA parameter set element from the beacon frame and initialize the OBO process. Specifically, the first station STA1 sets OCWmin and OCWmax according to the UORA parameter set element and initializes OCW. The first station STA1 randomly selects 10 in OCW and sets the OBO counter to 10. In addition, the second station STA2 sets OCWmin and OCWmax according to the UORA parameter set element and initializes OCW. The second station STA2 arbitrarily selects 12 in OCW and sets the OBO counter to 12.

[0179] The first station STA1 and the second station STA2 receive a trigger frame from the first AP AP1. In this case, the trigger frame indicates two RUs, where the RUs are allocated for random access. One RU is included in a primary channel having a frequency bandwidth of 20 MHz, and the other RU is not included in a primary channel having a frequency bandwidth of 20 MHz. Since the first station STA1 only supports a frequency bandwidth equal to or less than 20 MHz, the first station STA1 decrements the OBO counter by 1 and sets the OBO counter to 9. Since the second station STA2 also supports a frequency bandwidth equal to or wider than 20 MHz, the second station STA2 decrements the OBO counter by 2 and sets the OBO counter to 10.

[0180] In Figure 19 In an embodiment, the first station STA1 only supports a frequency band equal to or less than 20 MHz, and the second station STA2 supports a frequency band equal to or greater than 20 MHz, as in Figure 18 In an embodiment. The description of the operations of the first station STA1 and the second station STA2 will be omitted, which are the same as those in Figure 18 In an embodiment.

[0181] The first station STA1 and the second station STA2 receive a trigger frame from the first AP AP1. In this case, the trigger frame indicates two RUs, and the RUs are allocated for random access. The frequency bandwidth of one RU is equal to or less than 20 MHz, and the frequency bandwidth of the other RU is greater than 20 MHz. Since the first station STA1 only supports a frequency bandwidth equal to or less than 20 MHz, the first station STA1 decrements the OBO counter by 1 and sets the OBO counter to 9. Since the second station STA2 also supports a frequency bandwidth equal to or greater than 20 MHz, the second station STA2 decrements the OBO counter by 2 and sets the OBO counter to 10.

[0182] Figures 20 to 21 An operation of a wireless communication terminal that only supports a PPDU with a bandwidth equal to or less than 80 MHz according to an embodiment of the present invention to perform random access is shown.

[0183] In Figure 20 the embodiment, the first station STA1 only supports a frequency band equal to or less than 80 MHz, and the second station STA2 supports a frequency band equal to or greater than 80 MHz (160 MHz, 80 + 80 MHz). The description of the same operations of the first station STA1 and the second station STA2 as those in Figures 18 to 19 the embodiment will be omitted.

[0184] The first station STA1 and the second station STA2 receive a trigger frame from the first AP AP1. In this case, the trigger frame indicates two RUs, and the RUs are allocated for random access. One RU is included in the primary channel with a frequency bandwidth of 80 MHz, and the other RU is not included in the primary channel with a frequency bandwidth of 80 MHz. Since the first station STA1 only supports a frequency bandwidth equal to or less than 80 MHz, the first station STA1 decrements the OBO counter by 1 and sets the OBO counter to 9. Since the second station STA2 also supports a frequency bandwidth equal to or wider than 80 MHz, the second station STA2 decrements the OBO counter by 2 and sets the OBO counter to 10.

[0185] In Figure 21 the embodiment, the first station STA1 only supports a frequency band of 80 MHz or less, and the second station STA2 supports a frequency band equal to or greater than 80 MHz (160 MHz, 80 + 80 MHz), as in Figure 20 the embodiment. The description of the same operations of the first station STA1 and the second station STA2 as those in Figures 18 to 20 the embodiment will be omitted.

[0186] The first station STA1 and the second station STA2 receive trigger frames from the first AP AP1. In this case, the trigger frame indicates two RUs, and the RUs are allocated for random access. The frequency bandwidth of one RU is equal to or less than 80 MHz, and the frequency bandwidth of the other RU is greater than 80 MHz. Since the first station STA1 only supports a frequency bandwidth equal to or less than 80 MHz, the first station STA1 decrements the OBO counter by 1 and sets the OBO counter to 9. Since the second station STA2 also supports a frequency bandwidth equal to or greater than 20 MHz, the second station STA2 decrements the OBO counter by 2 and sets the OBO counter to 10.

[0187] In the above random access operation of the wireless communication terminal, the wireless communication terminal receives information on OBO-related parameters from the base station wireless communication terminal associated with the wireless communication terminal, and sets the OBO-related parameters according to the received information. Specifically, a UORA parameter set element is received from the base station wireless communication terminal associated with the wireless communication terminal, and the OBO-related parameters are set based on the UORA parameter set element. A wireless communication terminal not associated with the base station wireless communication terminal can perform random access based on the trigger frame sent by the base station wireless communication terminal. In this case, the method of setting the OBO-related parameters and the method of initializing the OBO process by the non-associated wireless communication terminal become problems. This will be described in detail with reference to Figures 22 to 25 If there is no other description in this specification, the non-associated wireless communication terminal can represent a wireless communication terminal not associated with any base station wireless communication terminal.

[0188] Figure 22 Illustrates the random access operation of a non-associated wireless communication terminal according to an embodiment of the present invention.

[0189] When the wireless communication terminal receives a trigger frame for triggering the random access of the wireless communication terminal from the base station wireless communication terminal not associated with the wireless communication terminal, the wireless communication terminal can start the OBO process based on the information on the OBO-related parameters sent by the corresponding base station wireless communication terminal. Specifically, the wireless communication terminal can receive a UORA parameter set element from the wireless communication terminal not associated with the base station wireless communication terminal. In this case, when the wireless communication terminal receives a trigger frame for triggering the random access of the wireless communication terminal from the corresponding base station wireless communication terminal, the wireless communication terminal can set OCWmin and OCWmax according to the UORA parameter set element and start the OBO process.

[0190] When a wireless communication terminal receives a trigger frame that triggers random access of the wireless communication terminal from a wireless communication terminal different from the base station wireless communication terminal that sends the UORA parameter set element, the wireless communication terminal may not perform the OBO-related process according to the received UORA parameter set element. Specifically, when a wireless communication terminal receives a trigger frame that triggers random access of the wireless communication terminal from a wireless communication terminal different from the base station wireless communication terminal that sends the UORA parameter set element, the wireless communication terminal may not decrement the OBO counter based on the trigger frame. To this end, the wireless communication terminal may compare the identifier of the base station wireless communication terminal that sends the UORA parameter set element with the identifier of the base station wireless communication terminal that sends the trigger frame. In this case, the identifier of the base station wireless communication terminal may be a MAC address or a BSSID. In the above embodiment, the trigger frame for triggering random access may be a trigger frame for triggering random access of a non-associated wireless communication terminal.

[0191] In addition, when a wireless communication terminal receives a new UORA parameter set element from a wireless communication terminal different from the base station wireless communication terminal that sends the UORA parameter set element, the wireless communication terminal may not initialize the OBO process based on the newly received UORA parameter set element. In this case, the initialization of the OBO process includes at least one of OBO counter initialization and OCW initialization. Additionally, when a wireless communication terminal receives a new UORA parameter set element from a wireless communication terminal different from the base station wireless communication terminal that sends the UORA parameter set element, the wireless communication terminal may not set the OBO-related parameters based on the newly received UORA parameter set element. In this case, the setting of the OBO-related parameters may include at least one of OCWmin setting and OCWmax setting. To this end, the wireless communication terminal may compare the identifier of the base station wireless communication terminal that sends the UORA parameter set element with the identifier of the base station wireless communication terminal that sends the new UORA parameter set element. In this case, the identifier of the base station wireless communication terminal may be a MAC address or a BSSID. Through this embodiment, it is possible to prevent a non-associated wireless communication terminal from continuously initiating the OBO process or performing random access while compromising the fairness with other wireless communication terminals.

[0192] In Figure 22In the embodiment, the first station STA1 is a wireless communication terminal that is not associated with any base station wireless communication terminal. The first station STA1 receives a beacon frame from the first AP AP1 and obtains a UORA parameter set element from the received beacon frame. The first station STA1 sets OBO-related parameters according to the obtained UORA parameter set element and initializes the OBO process. Specifically, the first station STA1 sets OCWmin and OCWmax according to the obtained UORA parameter set element and selects an arbitrary integer in the OCW. In this case, the arbitrarily selected integer is 10, and the first station STA1 sets the OBO counter to 10.

[0193] The first station STA1 receives a trigger frame from the first AP AP1, and the trigger frame indicates that two RUs are allocated for random access. In this case, the first station STA1 decrements the OBO counter by 2 and sets the OBO counter to 8.

[0194] The first station STA1 receives a trigger frame from the second AP AP2, and the trigger frame indicates that two RUs are allocated for random access. Since the first AP AP1 and the second AP AP2 that send the UORA parameter set element for setting OBO-related parameters have different identifiers, the first station STA1 maintains the OBO counter as it is.

[0195] The first station STA1 receives a beacon frame from the second AP AP2, and the received beacon frame includes a UORA parameter set element. Since the first AP AP1 and the second AP AP2 that send the UORA parameter set element for setting OBO-related parameters have different identifiers, the first station STA1 does not update the OBO-related parameters.

[0196] The first station STA1 receives a beacon frame from the first AP AP1 and obtains a UORA parameter set element from the received beacon frame. Since the first station STA1 receives the UORA parameter set element from the first AP AP1 that sends the UORA parameter set element for setting OBO-related parameters again, the first station STA1 updates the OBO-related parameters according to the newly received UORA parameter set element.

[0197] According to the reference Figure 22 In the described embodiment, the non-associated wireless communication terminal may not participate in the random access triggered by a base station wireless communication terminal other than the base station wireless communication terminal that receives the first UORA parameter set element. Therefore, a method to solve this is needed.

[0198] Figure 23 Shows the random access operation of an associated wireless communication terminal according to an embodiment of the present invention.

[0199] When a non-associated wireless communication terminal performs an OBO process for a first base station wireless communication terminal and performs an OBO process for a second base station wireless communication terminal, the non-associated wireless communication terminal may initiate the OBO process. Specifically, the non-associated wireless communication terminal may maintain OBO-related parameters and an OBO process for each base station wireless communication terminal. In a particular embodiment, the non-associated wireless communication terminal may set OBO-related parameters for each base station wireless communication terminal. Specifically, the non-associated wireless communication terminal may set OBO-related parameters for each base station wireless communication terminal based on information about the OBO-related parameters received from each base station wireless communication terminal. In a particular embodiment, when a wireless communication terminal receives a UORA parameter set element from any one of the base station wireless communication terminals, the wireless communication terminal may update the OBO-related parameters of the corresponding UORA parameter set element. In this case, the OBO-related parameters may be at least one of OCWmin and OCWmax.

[0200] In addition, the non-associated wireless communication terminal may initialize the OBO process for each base station wireless communication terminal. Specifically, the non-associated wireless communication terminal may maintain an OBO counter for each base station wireless communication terminal. In a particular embodiment, when the non-associated wireless communication terminal receives a trigger frame for triggering random access from any one of the base station wireless communication terminals, the non-associated wireless communication terminal is able to decrement the OBO counter for the base station wireless communication terminal based on the number of RUs for random access indicated by the corresponding trigger frame.

[0201] In Figure 23 the embodiment, the first station STA1 is a wireless communication terminal non-associated with any base station wireless communication terminal. The first station STA1 receives a beacon frame from the first AP AP1 and obtains a UORA parameter set element from the received beacon frame. The first station STA1 sets an OBO-related parameter set 1 for the first AP AP1 according to the obtained UORA parameter set element and initializes the OBO process. Specifically, the first station STA1 sets OCWmin and OCWmax for the first AP AP1 according to the obtained UORA parameter set element and selects a random integer in the OCW for the first AP AP1. In this case, the randomly selected integer is 10, and the first station STA1 sets the OBO counter of the first AP AP1 to 10.

[0202] The first station STA1 receives a trigger frame from the first AP AP1, and the trigger frame indicates that two RUs are allocated for random access. In this case, the first station STA1 decrements the OBO counter of the first AP AP1 by 2 and sets the OBO counter of the first AP AP1 to 8.

[0203] The first station STA1 receives a beacon frame from the second AP AP2 and obtains a UORA parameter set element from the received beacon frame. Since the first AP AP1 and the second AP AP2 that send the UORA parameter set element for setting OBO-related parameters have different identifiers, the first station STA1 sets the OBO-related parameter set 2 for the second AP AP2 according to the obtained UORA parameter set element and initializes the OBO process of the second AP AP2. Specifically, the first station STA1 sets OCWmin and OCWmax for the second AP AP2 according to the obtained UORA parameter set element and selects a random integer in the OCW for the second AP AP2. In this case, the randomly selected integer is 12, and the first station STA1 sets the OBO counter of the second AP AP2 to 12. In this case, the first station STA1 does not update the OBO-related parameters of the first AP AP1 and does not initialize the OBO process.

[0204] The first station STA1 receives a trigger frame from the second AP AP2, and the trigger frame indicates that two RUs are allocated for random access. In this case, the first station STA1 decrements the OBO counter of the second AP AP2 by 2 and sets the OBO counter of the second AP AP2 to 10. In this case, the first station STA1 maintains the OBO counter of the first AP AP1 as 8 as it is.

[0205] According to Figures 22 to 23 the embodiment, when the wireless communication terminal does not receive information about OBO-related parameters from the base station wireless communication terminal, the wireless communication terminal cannot participate in random access. Therefore, the operation of the wireless communication terminal is necessary to solve such a problem.

[0206] Figure 24 Shows the random access operation of the associated wireless communication terminal according to an embodiment of the present invention.

[0207] The non-associated wireless communication terminal can perform random access using the default values predefined for each OBO-related parameter. Specifically, the non-associated wireless communication terminal can set a predetermined value as the default value of OCWmin in OCWmin. In addition, the non-associated wireless communication terminal can set a predetermined value as the default value of OCWmax in OCWmax. In this case, the value predetermined as the default value of OCWmin may not be the value specified by the base station wireless communication terminal. Additionally, the value predetermined as the default value of OCWmax may not be the value specified by the base station wireless communication terminal. Specifically, when the non-associated wireless communication terminal does not receive information about the OBO-related parameter from the base station wireless communication terminal, the non-associated wireless communication terminal can use the predetermined default value for each OBO-related parameter. In this case, when the non-associated wireless communication terminal receives information about the OBO-related parameter from the base station wireless communication terminal, the non-associated wireless communication terminal can set the OBO-related parameter according to the information about the OBO-related parameter.

[0208] In a specific embodiment, when the non-associated wireless communication terminal uses the predetermined default value for each OBO-related parameter, even if the non-associated wireless communication terminal receives information about the OBO-related parameter from the base station wireless communication terminal, the relevant parameter may not be set according to the information about the parameter related to OBO. In a specific embodiment, when the non-associated wireless communication terminal uses the predetermined default value for each OBO-related parameter, performs random access to the first base station wireless communication terminal, and performs random access to the second base station wireless communication terminal, the non-associated wireless communication terminal may not initiate the OBO process. For example, when the non-associated wireless communication terminal uses the predetermined default value for each OBO-related parameter, performs random access to the first base station wireless communication terminal, and performs random access to the second base station wireless communication terminal, the non-associated wireless communication terminal can use the value of the OBO counter used in the OBO process for the first base station wireless communication terminal in the random access to the second base station wireless communication terminal.

[0209] In Figure 24 the embodiment, when the UORA parameter set element is not received from the base station wireless communication terminal, the first station STA1 sets OCWmin to the default value OCWmin and sets OCWmax to the OCWmax value. In this case, the first station STA1 initiates the OBO process and selects 10 as a random integer within OCW. The first station STA1 sets the randomly selected 10 as the OBO count.

[0210] The first station STA1 receives a beacon frame from the first AP AP1 and obtains the UORA parameter set element from the beacon frame. The first station STA1 does not initialize the OBO process but maintains the value of the OBO-related parameter as it is.

[0211] The first station STA1 receives a trigger frame from the first AP AP1 indicating the allocation of two RUs for random access. In this case, the first station STA1 decrements the OBO counter by 2 and sets the OBO counter to 8.

[0212] In addition, the first station STA1 receives a trigger frame from the second AP AP2 indicating the allocation of two RUs for random access. In this case, the first station STA1 decrements the OBO counter by 2 and sets the OBO counter to 6.

[0213] Figure 25 Shows the random access operation of an associated wireless communication terminal according to an embodiment of the present invention.

[0214] The non-associated wireless communication terminal can send management frames by randomly accessing the base station wireless communication terminal. Specifically, the non-associated wireless communication terminal can send at least one of a probe request frame, an authentication request frame, and an association request frame by randomly accessing the base station wireless communication terminal. When the wireless communication terminal sends a trigger-based PPDU in response to a trigger frame, the wireless communication terminal can perform transmission in the format of an aggregated MAC protocol data unit (A-MPDU) according to the MAC padding rule. However, since the probe request frame, the authentication request frame, and the association request frame are MAC management protocol data units (MMPDUs) that do not request an immediate response, transmission using A-MPDU may not be allowed. In this case, an immediate response can indicate sending a response within a predetermined time period within one transmission opportunity (TXOP). The predetermined time period can be SIFS. Aggregation of MMPDUs into A-MPDU can be allowed to send A-MPDU for transmission by random access of the non-associated wireless communication terminal. In this case, the MMPDU can include at least one of a probe request frame, an authentication request frame, an association request frame, and a re-association request frame. Specifically, in the context of the content of the A-MPDU, the transmission of the MMPDU can be included in the context of data that does not request an immediate response. In a specific embodiment, the probe request frame, the authentication request frame, and the association request frame can be specified by the type of MPDU that can be included in the context of data that does not require an immediate response among the content of the A-MPDU. In yet another specific embodiment, the context of the content of the A-MPDU can be defined. Specifically, the context of setting up the association process can be specified. In the context of the association process, the defined A-MPDU does not require an immediate response, and QoS null frames or action no-ACK frames can be aggregated through MMPDUs. For example, it can be specified that in the context of the association process, the defined A-MPDU does not require an immediate response, and QoS null frames or action no-ACK frames are allowed to be aggregated with the probe request frame, the authentication request frame, or the association request frame.

[0215] In Figure 25In an embodiment, a non-associated first station STA1 receives a beacon frame from an AP. The first station STA1 obtains a UORA parameter set element from the beacon frame and initializes an OBO process based on the obtained UORA parameter set element. The first station STA1 sets an OBO counter to 3. The first station STA1 receives a trigger frame from the AP, and the trigger frame indicates that four RUs are allocated for random access. The first station STA1 decrements the OBO counter to 0 based on the trigger frame. Accordingly, the first station STA1 transmits a trigger-based PPDU (HE TRIG PPDU) to the AP via the RU allocated for random access, and the trigger-based PPDU (HE TRIG PPDU) includes a probe request frame or an association request frame aggregated into an A-MPDU. The AP transmits a multi-STA block Ack (M-BA) for multiple stations.

[0216] When a wireless communication terminal performing random access is scheduled to transmit an uplink transmission via a trigger frame, reference will be made to Figure 26 describe the operation of the wireless communication terminal.

[0217] Figure 26 illustrates the random access operation of a wireless communication terminal when the wireless communication terminal according to an embodiment of the present invention is scheduled for an uplink transmission via a trigger frame.

[0218] When a wireless communication terminal performing random access is scheduled for an uplink transmission via a trigger frame, it may be a problem whether the corresponding wireless communication terminal can decrement an OBO counter based on the RU allocated for random access indicated by the trigger frame. Even when a wireless communication terminal performing random access is scheduled for an uplink transmission via a trigger frame, if the OBO counter is decremented based on the RU allocated for random access indicated by the trigger frame, the corresponding wireless communication terminal may have a too high priority compared to other wireless communication terminals. Accordingly, the equality between wireless communication terminals may be violated. When a wireless communication terminal performing random access is scheduled for an uplink transmission via a trigger frame, the corresponding wireless communication terminal can maintain the OBO counter regardless of the number of RUs allocated for random access indicated by the trigger frame.

[0219] When a wireless communication terminal scheduled by a trigger frame for uplink transmission performs uplink transmission, the trigger frame may indicate that carrier sensing is required. In this case, when it is determined based on the result of carrier sensing that the RU to be used for uplink transmission is busy, the corresponding wireless communication terminal may not attempt uplink transmission. Specifically, when a wireless communication terminal scheduled by a trigger frame for uplink transmission performs uplink transmission using the CS required field, the trigger frame may indicate that carrier sensing is required. Moreover, carrier sensing may include energy detection (ED). When it is determined through carrier detection that the RU to be used for uplink transmission is busy, the random access operation of a wireless communication terminal scheduled by a trigger frame for uplink transmission is a problem. This is because the uplink transmission is indicated by the trigger frame, but the corresponding wireless communication terminal does not perform uplink transmission.

[0220] When a trigger frame schedules the transmission of a wireless communication terminal performing random access for uplink and indicates that carrier sensing is required for uplink transmission, the wireless communication terminal performing random access can operate as follows. When it is determined by carrier sensing that the RU to be used for uplink transmission is busy, the wireless communication terminal performing random access can decrement the OBO counter based on the RU allocated for random access indicated by the trigger frame. Specifically, the wireless communication terminal performing random access can decrement the OBO counter by the number of RUs allocated for random access indicated by the trigger frame. In addition, when it is determined through carrier detection that the RU to be used for uplink transmission is busy, even if the OBO counter is 0 or the OBO counter reaches 0, the wireless communication terminal performing random access can maintain the OBO counter at 0 and may not attempt uplink transmission. In another specific embodiment, when it is determined through carrier detection that the RU to be used for uplink transmission is busy and the OBO counter is 0 or the OBO counter reaches 0, the wireless communication terminal performing random access can randomly select any one of the RUs allocated for random access and attempt uplink transmission.

[0221] In Figure 26 the embodiment, the first station STA1 receives a beacon frame from the AP. The first station STA1 obtains the UORA parameter set element from the beacon frame and initializes the OBO process according to the obtained UORA parameter set element. The first station STA1 sets the OBO counter to 3. The first station STA1 receives an indication trigger frame from the AP, which indicates that four RUs are allocated for random access and schedules the uplink transmission of the first station STA1. Since the trigger frame schedules the uplink transmission of the first station STA1, the first station STA1 maintains the OBO counter as it is. In addition, the first station STA1 sends a TB PPDU (HE TRIGPPDU) to the AP according to the information indicated by the trigger frame. The AP sends a multi-STA block Ack (M-BA) for multiple stations.

[0222] In the above embodiments, it is described that a wireless communication terminal can obtain information about the OBO counter from a beacon frame. In this way, the wireless communication terminal can obtain information about the BSS from the beacon frame. In addition, the base station wireless communication terminal can periodically transmit a beacon frame to signal information about the BSS. Reference will be made to Figures 27 to 35 Describe a specific transmission method for the beacon frame.

[0223] Figure 27 Illustrate a conventional PPDU format according to an embodiment of the present invention.

[0224] The types of conventional PPDUs that can be transmitted by a conventional wireless communication terminal may include at least one of a non-HT PPDU, an HT mixed PPDU, an HT-undeveloped PPDU, and a VHT PPDU.

[0225] Figure 27 (a) Illustrates the format of a non-HT PPDU. The non-HT PPDU format includes: a short training field including a relatively short training signal, a long training field including a relatively long training signal, a signal field including signaling information, and a data field including the payload of the PPDU. Figure 27 (b) Illustrates the format of an HT mixed PPDU. The HT mixed PPDU includes L-STF, L-LTF, and L-SIG fields for conventional wireless communication terminals that do not support HT mixed PPDUs. Additionally, the HT mixed PPDU includes: an HT-SIG field including signaling information, an HT-STF including a relatively short training signal, at least one HT-LTF including a relatively long training signal, and a data field including the payload of the PPDU. Figure 27 (c) Illustrates the format of an HT-undevloped PPDU. The HT-undevloped PPDU includes: an HT-GF-STF, which includes a relatively short training signal and an HT-SIG field including signaling information, at least one HT-LTF including a relatively long training signal, and a data field including the payload of the PPDU. Figure 27 (d) Illustrates the format of a VHT PPDU. The VHT PPDU includes L-STF, L-LTF, and L-SIG fields for conventional wireless communication terminals that do not support VHT PPDUs. Additionally, the VH PPDU includes: a VHT-SIG-A field including signaling information, a VHT-STF including a relatively short training signal, at least one VHT-LTF including a relatively long training signal, and a data field including the payload of the PPDU. Additionally, the VHT PPDU may include a VHT-SIG-B field for signaling additional information.

[0226] Figure 28 Illustrate a non-conventional PPDU format according to an embodiment of the present invention.

[0227] A wireless communication terminal according to an embodiment of the present invention may support one or more non - traditional PPDU formats. In addition, a wireless communication terminal according to an embodiment of the present invention may select and use any one of a plurality of non - traditional PPDU formats according to the purpose and objective of transmitting the PPDU. Specifically, the wireless communication terminal may support at least one of HE SU PPDU, HE MU PPDU, HE extended range SU PPDU, and HE trigger - based PPDU. The HE - SIG - A field and the HE - SIG - B field of the non - traditional PPDU may be referred to as pre - HE modulation fields. Additionally, the HE - STF, HE - LTF, and data fields of the non - traditional PPDU may be referred to as HE modulation fields. The pre - HE modulation fields and the HE modulation fields can be modulated with different parameter sets.

[0228] Figure 28 (a) shows the format of the HE SU PPDU. The wireless communication terminal may use the HE SU PPDU for single - user (SU) transmission. The HE SU PPDU may include L - STF, L - LTF, and L - SIG fields for traditional wireless communication terminals. In addition, the HE SU PPDU includes RL - SIG for signaling the non - traditional PPDU, the HE - SIG - A field including signaling information, the HE - STF including a relatively short training signal, at least one HE - LTF including a relatively long training signal, and a data field including the payload of the PPDU. Additionally, the HE SU PPDU may include a packet extension (PE) field for ensuring processing time. The duration of the PE field may be determined by the TXVECTOR parameter PE_DURATION. The HE SU PPDU is capable of delivering one PSDU.

[0229] Figure 28 (b) shows the format of the HE MU PPDU. The wireless communication terminal may use the HE MU PPDU to transmit to one or more users. In this case, the wireless communication terminal may not use the HE MU PPDU in response to a trigger. The HE MU PPDU has a format similar to that of the HE SU PPDU and may further include the HE - SIG - B field compared to the HE SU PPDU. The HE - SIG - B field includes information for multi - user (MU) transmission. The HE MU PPDU can deliver more than one PSDU.

[0230] Figure 28(c) shows the format of a HE-triggered PPDU. In the above embodiments, the TB PPDU may refer to a HE-triggered PPDU. A wireless communication terminal may use a HE-triggered PPDU to respond to a trigger frame or a UL MU response scheduling A-control field. A HE-triggered PPDU may include a HE-STF, which has a longer duration than the HE SU PPDU format.

[0231] Figure 28 (d) shows the format of a HE extended range SU PPDU. A wireless communication terminal may use a HE extended range SU PPDU for extended range transmission. The HE extended range SU PPDU has a similar format to the HE SU PPDU, and the duration of the HE-SIG-A field of the HE extended range SU PPDU is twice the duration of the HE-SIG-A field of the HE SU PPDU. The wireless communication terminal is capable of performing transmission using four symbols. For example, four symbols can be transmitted in the HE-SIG-A field of the HE extended range SU PPDU. The four symbols used to transmit the HE-SIG-A field may be symbols repeated in the time domain. The four symbols for transmitting the HE-SIG-A field are called HE-SIG-A1, HE-SIG-A2, HE-SIG-A3, and HE-SIG-A4 in chronological order. In this case, HE-SIG-A1 and HE-SIG-A2 may transmit the same signal, and HE-SIG-A3 and HE-SIG-A4 may transmit the same signal. In addition, when transmitting a HE extended range SU PPDU, compared with the case of transmitting the L-STF and L-LTF of other non-conventional PPDUs, the wireless communication terminal may increase the transmission power by 3 dB. In addition, when transmitting four additional tones (subcarrier indices k = -28, -27, 27, and 28) of the L-SIG field and the RL-SIG field, compared with transmitting the L-STF and L-LTF of other non-conventional PPDUs, the wireless communication terminal may increase the transmission power by 3 dB. Through these operations, the wireless communication terminal can increase the reception probability of the HE extended range SU PPDU.

[0232] Figure 29 Shows the coverage range of a HE extended range SU PPDU and the transmission coverage range of a conventional PPDU according to an embodiment of the present invention.

[0233] As referred to Figure 28As described above, when transmitting a HE extended range SU PPDU, the wireless communication terminal performs various operations for long-distance transmission. Therefore, the transmission coverage range of the HE extended range SU PPDU is wider than that of the conventional PPDU. Due to this, even a wireless communication terminal that can receive the HE extended range SU PPDU may not receive the conventional PPDU format. For example, in Figure 29 the situation shown, the transmission coverage range of the HE extended range SU PPDU is wider than that of the conventional PPDU (non-HE PPDU). Therefore, the first station STA1 can receive both the conventional PPDU (non-HE PPDU) and the HE extended range SU PPDU. The second station STA2 can only receive the HE extended range SU PPDU without receiving the conventional PPDU (non-HE PPDU). When there is information to be transmitted in the conventional PPDU format, a wireless communication terminal located outside the coverage range of the conventional PPDU format cannot use this information. The wireless communication terminal can use the conventional PPDU format to transmit a beacon frame. Although a wireless communication terminal located outside the coverage range of the conventional PPDU format can communicate with the base station wireless communication terminal using the HE extended range SU PPDU, it cannot receive the BSS information and, therefore, cannot communicate with the base station wireless communication terminal. Therefore, the base station wireless communication terminal can transmit a dual beacon frame. This will be described with reference to Figure 30 this.

[0234] Figure 30 FIG. shows the dual beacon transmission operation of the base station wireless communication terminal according to an embodiment of the present invention.

[0235] The base station wireless communication terminal can use multiple PPDU formats to transmit a beacon frame. Specifically, the base station wireless communication terminal can use two PPDU formats with different transmission coverage ranges to transmit a beacon frame. The wireless communication terminal can transmit a beacon frame using the conventional PPDU format and transmit a beacon frame using the PPDU format for wide-range transmission. In this case, the PPDU format for wide-range transmission can be the above-mentioned HE extended range SU PPDU. By this operation, the base station wireless communication terminal can increase the possibility that the wireless communication terminals around the base station wireless communication terminal receive the beacon frame. For ease of explanation, the fact that the base station wireless communication terminal uses two PPDU formats with different transmission coverage ranges to transmit a beacon frame is referred to as a dual beacon.

[0236] A base station wireless communication terminal may transmit a beacon frame based on a predetermined time period. In this case, the time point at which the base station wireless communication terminal attempts to transmit the beacon frame may be referred to as the Target Beacon Transmission Time (TBTT). The TBTT may continue at a predetermined time interval. In this case, the predetermined time interval may be referred to as the beacon interval. When the channel on which the base station wireless communication terminal transmits the beacon frame is busy, the base station wireless communication terminal may attempt to transmit the beacon frame again after a predetermined time. For example, when the channel on which the base station wireless communication terminal transmits the beacon frame is idle, the base station wireless communication terminal may transmit the beacon frame.

[0237] The base station wireless communication terminal may attempt to transmit a legacy PPDU including a beacon frame at the TBTT and attempt to transmit a PPDU for a wide range transmission including the beacon frame after a predetermined time from the TBTT. At this time, the predetermined time may be half of the time interval between TBTTs. For example, the TBTT of the beacon frame included in the legacy PPDU may be the Timing Synchronization Function (TSF) value 0, and the TBTT of the beacon frame included in the legacy PPDU may be repeated for each beacon interval. The TBTT of the beacon frame included in the PPDU for wide range transmission may be the time point after half of the beacon interval from the TSF value 0. In addition, the TBTT of the beacon frame included in the PPDU for wide range transmission may be repeated for each beacon interval.

[0238] The base station wireless communication terminal may use an operation element to signal whether dual beacons are used. In this case, the operation element may be a HE operation element. In addition, each beacon frame transmitted in a different PPDU format may include different types of signaling information. Specifically, each beacon frame transmitted in a different PPDU format may include different types of elements.

[0239] In Figure 30 In an embodiment, the base station wireless communication terminal attempts to transmit a legacy PPDU including a beacon frame at the TBTT for the legacy PPDU including the beacon frame. The base station wireless communication terminal transmits the legacy PPDU including the beacon frame, and the first station STA1 receives the legacy PPDU including the beacon frame. The second station STA2, which is farther from the base station wireless communication terminal than the first station STA1, does not receive the legacy PPDU including the beacon frame.

[0240] At the time point after half of the beacon interval of the legacy PPDU including the beacon frame has elapsed from the TBTT for the legacy PPDU including the beacon frame, the base station wireless communication terminal attempts to transmit a HE Extended Range SU PPDU including the beacon frame. The base station wireless communication terminal transmits the HE Extended Range SU PPDU including the beacon frame, and the first station STA1 and the second station STA2 receive the HE Extended Range SU PPDU including the beacon frame.

[0241] At a time point after a beacon interval has elapsed since the TBTT of a conventional PPDU including a beacon frame, the base station wireless communication terminal attempts to transmit the conventional PPDU including the beacon frame. At a time point when half of the beacon interval has elapsed since this time, the base station wireless communication terminal attempts to transmit a HE extended range SU PPDU including the beacon frame.

[0242] The base station wireless communication terminal can signal information about a specific time point using the above TBTT. For example, the base station wireless communication terminal can use the TBTT to signal the start time point of a change in BSS color, which is an identifier indicating the BSS. This will be described in more detail with reference to Figure 31 this.

[0243] Figure 31 Shows the format of the BSS color change announcement element according to an embodiment of the present invention.

[0244] The base station wireless communication terminal can transmit a beacon frame including the BSS color change announcement element to notify of a change in BSS color and the new BSS color value. In this case, the BSS color change announcement element can include a field indicating the time point of the BSS color change. Additionally, the BSS color change announcement element can include a field indicating the value of the changed BSS color. For example, the BSS color change announcement element can include a color switch countdown field. The color switch countdown field can indicate the number of TBTTs remaining before the BSS color change time point. The BSS color change announcement element can include a new BSS color information field. The new BSS color information field can indicate the new BSS color value to be used as the BSS color of the corresponding BSS. The new BSS color information field can include a new BSS color subfield, and the new BSS color subfield can represent the value of the new BSS color to be used as the BSS color of the corresponding BSS. The specific format of the BSS color change announcement element can be the same as that shown in Figure 31 this.

[0245] For ease of explanation, the TBTT that causes the color change countdown value to reach 0 and changes the BSS color is referred to as the BSS color change TBTT. Before reaching the BSS color change TBTT, the base station wireless communication terminal inserts the BSS color value before the BSS change into the BSS color subfield of the HE operation element. Additionally, when reaching the BSS color change TBTT, the base station wireless communication terminal sets the BSS color disable subfield of the HE operation element to 0, inserts the changed BSS color value into the BSS color subfield of the HE operation element, and starts using the changed value of the BSS color. Additionally, a wireless communication terminal that receives the BSS color change announcement element can use the changed BSS color value from the BSS color change TBTT. In this case, the wireless communication terminal obtains the changed value of the BSS color from the BSS color change notification element.

[0246] To enable all wireless communication terminals in the BSS to use the same BSS color value, the base station wireless communication terminal and the wireless communication terminal can operate as follows. The base station wireless communication terminal that sends the BSS color change announcement element can use the previous BSS color value until reaching the BSS color change TBTT and use the changed BSS color value after the BSS color change TBTT. Additionally, until the base station wireless communication terminal that sends the BSS color change announcement element reaches the BSS color change TBTT, it may not be allowed to change the BSS color change TBTT indicated by the BSS color change announcement element. When the base station wireless communication terminal uses dual beacons, the BSS color change time point can be determined differently according to the format of the PPDU that the wireless communication terminal can receive. Reference will be made Figure 32 to describe this.

[0247] Figure 32 Shows the BSS color change operation of the base station wireless communication terminal when the base station wireless communication terminal uses dual beacons according to an embodiment of the present invention.

[0248] Due to the distance between the wireless communication terminal and the base station wireless communication terminal, the wireless communication terminal may receive only one of the PPDU formats in the PPDU format for dual beacons. In this case, the wireless communication terminal that receives only one PPDU format of the PPDU format for dual beacons may determine the BSS color change TBTT differently from the wireless communication terminal that receives all PPDU formats for dual beacons. Specifically, since the wireless communication terminal may not recognize the transmission of the beacon frame included in the PPDU format that the wireless communication terminal may not receive, it may not be possible to accurately determine the number of remaining TBTTs until the BSS color changes. In addition, the wireless communication terminal that receives all PPDU formats for dual beacons may be confused about how to set the TBTT standard when determining the BSS color change TBTT. For example, the wireless communication terminal that receives all PPDU formats for dual beacons may have difficulty determining whether the value indicated by the countdown field indicates the TBTI of all types of PPDUs including the beacon frame or the TBTT of a specific type of PPDU format that only includes the beacon frame.

[0249] In Figure 32 the embodiment, the base station wireless communication terminal attempts to transmit a legacy PPDU including a beacon frame at the TBTT for the legacy PPDU including the beacon frame. The base station wireless communication terminal transmits the legacy PPDU including the beacon frame, and the first station STA1 receives the legacy PPDU including the beacon frame. The second station STA2, which is farther from the base station wireless communication terminal than the first station STA1, does not receive the legacy PPDU including the beacon frame.

[0250] At a time point when half of the beacon interval of the legacy PPDU including the beacon frame has elapsed since the start of the TBTT for the legacy PPDU including the beacon frame, the base station wireless communication terminal attempts to transmit an HE extended range SU PPDU including the beacon frame. The base station wireless communication terminal transmits the HE extended range SU PPDU including the beacon frame, and the first station STA1 and the second station STA2 receive the HE extended range SU PPDU including the beacon frame.

[0251] In this case, the beacon frame included in the legacy PPDU signals the BSS color change TBTT based on the TBTT of the beacon frame included in the legacy PPDU. The beacon frame included in the legacy PPDU can signal the remaining TBTT count until the BSS color changes and the first time point (BSS color change TBTT 1) when the legacy PPDU including the first beacon frame is transmitted. The beacon frame included in the PPDU for wide range transmission signals the BSS color change TBTT based on the TBTT of the beacon frame included in the PPDU for wide range transmission. The beacon frame included in the PPDU for wide range transmission can signal the remaining TBTT count until the BSS color changes and the second time point (BSS color change TBTT 2) when the PPDU for wide range transmission including the first beacon frame is transmitted. Since the first station STA1 can receive two types of PPDU formats including the beacon frame, it may not be determined which of the first time point (BSS color change TBTT 1) or the second time point (BSS color change TBTT 2) the BSS color changes. In addition, the second station STA2 does not receive information about the first time point (BSS color change TBTT1). Therefore, the BSS color change time points of the first station STA1 and the second station STA2 may be different. As a result, interference may occur due to wireless communication terminals included in the same BSS and using different BSS color values.

[0252] The wireless communication terminal can perform operations other than the BSS color change operation based on the TBTT. For example, the wireless communication terminal can receive a set of UORA parameter elements related to random access in the TBTT and perform operations according to the reception of the set of UORA parameter elements. The operations received according to the set of UORA parameter elements can include at least one of OBO related parameter setting and OBO process initialization. As a result, when the base station wireless communication terminal uses dual beacons, there may be a problem that the time point at which the wireless communication terminal receives the set of UORA parameter elements related to random access and performs operations according to the reception of the set of UORA parameter elements becomes unclear. In addition, the wireless communication terminal located relatively close to the base station wireless communication terminal can receive the set of UORA parameter elements more frequently than the wireless communication terminal located relatively far from the base station wireless communication terminal. Therefore, the wireless communication terminal located relatively close to the base station wireless communication terminal can perform the OBO process more frequently than the wireless communication terminal located relatively far from the base station wireless communication terminal. As a result, equality among wireless communication terminals for random access may be a problem. For ease of explanation, the operation of the wireless communication terminal determining the operation execution time point based on the TBTT is referred to as an operation based on the TBTT. Reference will be made to Figures 33 to 34Describe an embodiment in which a wireless communication terminal can perform an operation based on TBTT without any problems even when using a dual beacon at a base station wireless communication terminal.

[0253] Figure 33 Illustrate a BSS color change operation of a base station wireless communication terminal when the base station wireless communication terminal uses a dual beacon according to another embodiment of the present invention.

[0254] When a base station wireless communication terminal uses a dual beacon, the wireless communication terminal may perform an operation based on TBTT at the TBTT of a beacon frame included in one PPDU format, and may not perform an operation based on TBTT at the TBTT of a beacon frame included in another PPDU format. Specifically, the wireless communication terminal may perform an operation based on TBTT on the TBTT of a beacon frame included in a legacy PPDU, and may not perform an operation based on TBTT on the TBTT of a beacon frame included in a PPDU for wideband transmission. In another specific embodiment, specifically, the wireless communication terminal may perform an operation based on TBTT on the TBTT of a beacon frame included in a PPDU for wideband transmission, and may not perform an operation based on TBTT on the TBTT of a beacon frame included in a legacy PPDU. For ease of explanation, the format of a PPDU including a beacon frame transmitted at the TBTT at which the wireless communication terminal performs an operation based on TBTT is referred to as a reference PPDU format. Beacons included in PPDU formats other than the reference PPDU format may also signal information related to the TBTT reference operation. In this case, the information related to the TBTT reference operation signaled by a beacon included in the reference PPDU format and the information related to the TBTT reference operation signaled by a beacon included in a PPDU format other than the reference PPDU format may indicate the same information.

[0255] In such an embodiment, the BSS color change announcement element may indicate the same BSS color change time point, regardless of the format of the PPDU including the BSS color change announcement element. Additionally, the color switch countdown field may indicate the number of times to send a reference PPDU format including a remaining beacon frame before changing the BSS color. If the color switch countdown field included in a PPDU format other than the reference PPDU format is 0, the color switch countdown field may indicate that the BSS color changes when sending a reference PPDU format including a beacon frame. For example, when a wireless communication terminal changes the BSS color in the TBTT of a beacon frame included in a legacy PPDU, the color switch countdown field may indicate the number of times to send a legacy PPDU including the remaining beacon frames before the BSS color changes. In this case, when the color switch countdown field of a beacon frame included in a PPDU for wideband transmission indicates 0, the wireless communication terminal may determine that the BSS color changes at the TBTT of the beacon frame included in a legacy PPDU sent after the corresponding beacon frame. Additionally, when the color switch countdown field of a beacon frame included in a legacy PPDU indicates 0, the wireless communication terminal may determine that the BSS color changes at the TBTT of the corresponding beacon frame.

[0256] In another specific embodiment, when a wireless communication terminal changes the BSS color in the TBTT of a beacon frame included in a PPDU for wideband transmission, the color switch countdown field may indicate the number of times to send a PPDU for wideband transmission including the remaining beacon frames before the BSS color changes. In this case, when the color switch countdown field of a beacon frame included in a legacy PPDU indicates 0, the wireless communication terminal can determine that the BSS color changes at the TBTT of the beacon frame included in a PPDU for wideband transmission sent after the corresponding beacon frame. Additionally, when the color switch countdown field of a beacon frame included in a PPDU for wideband transmission indicates 0, the wireless communication terminal can determine that the BSS color changes at the TBTT of the corresponding beacon frame.

[0257] In Figure 33 the embodiment of, the BSS color changes at the TBTT of a beacon frame included in a legacy PPDU (non-HE format). Thus, the beacon frame included in the HE extended range SU PPDU and the beacon frame included in the legacy PPDU (non-HE format) signal the TBTT of the beacon frame included in the legacy PPDU (non-HE format) as the BSS color change time point. Thus, the first station STA1 and the second station STA2 can change the BSS color based on the same time point. In the operations of the base station wireless communication terminal, the first station STA1, and the second station STA2, describe operations that are the same as the operations in the embodiment of Figure 31 the embodiment of.

[0258] In another specific embodiment, the wireless communication terminal may update OBO-related parameters based on the UORA parameter set element in the TBTT of the beacon frame included in the PPDU for wide range transmission, and may not update the OBO-related parameters based on the UORA parameter set element in the TBTT of the beacon frame included in the conventional PPDU. In addition, the wireless communication terminal may initialize the OBO process based on the UORA parameter set element in the TBTT of the beacon frame included in the PPDU for wide range transmission, and may not initialize the OBO process based on the UORA parameter set element of the TBTT of the beacon frame included in the conventional PPDU.

[0259] Figure 34 Illustrates the BSS color change operation of the base station wireless communication terminal when the base station wireless communication terminal uses a dual beacon according to another embodiment of the present invention.

[0260] When the base station wireless communication terminal uses a dual beacon, the base station communication terminal may signal information related to TBTT-based operations through the beacon frame included in one PPDU format, and may not signal information related to TBTT-based operations through the beacon frame included in other types of PPDU formats. Specifically, the base station wireless communication terminal may signal information related to TBTT-based operations through the beacon frame included in the conventional PPDU, and may not signal information related to TBTT-based operations through the beacon frame included in the PPDU for wide range transmission. Also in these embodiments, a reference Figure 33 PPDU format is described. The reference PPDU format may be a PPDU format that includes beacon signaling information related to TBTT-based operations. Additionally, the PPDU format that includes beacon signaling information related to TBTT-based operations may be a format of a PPDU having a wider transmission coverage range than other PPDU formats. This is because when the transmission coverage of the PPDU format that includes beacon signaling information related to TBTT-based operations is wide, more wireless communication terminals can receive information related to TBTT-based operations.

[0261] In a specific embodiment, the base station wireless communication terminal may signal the BSS color change announcement element through the beacon frame included in the PPDU for wide range transmission, and may not signal the BSS color change notification element through the beacon frame included in the conventional PPDU. Even in this embodiment, a reference PPDU format may be specified. Specifically, the reference PPDU format may be the PPDU for wide range transmission.

[0262] In Figure 34In the embodiment, the base station wireless communication terminal sends a BSS color change announcement element through a beacon frame included in an HE extended range SU PPDU, and does not send a BSS color change announcement element through a beacon frame (non-HE format) included in a legacy PPDU. In addition, the BSS color is changed based on the TBTT of the beacon frame included in the HE extended range SU PPDU. In the operations of the base station wireless communication terminal, the first station STA1, and the second station STA2, the description of the operations same as those in Figure 31 the embodiment is omitted.

[0263] In another specific embodiment, the base station wireless communication terminal may send a UORA parameter set element through a beacon frame included in a PPDU for wide range transmission, and may not send a UORA parameter set element through a beacon frame included in a legacy PPDU.

[0264] The base station wireless communication terminal may use STBC to send a beacon frame. In this case, the sent beacon frame may be referred to as an STBC beacon frame. When the base station wireless communication terminal uses both the STBC beacon frame and the beacon frame included in the HE extended range SU PPDU, the transmission time points of the STBC beacon frame and the HE extended range SU PPDU may overlap. Moreover, it may be difficult for a wireless communication terminal receiving the beacon frame to determine which beacon frame is sent at which time point. Therefore, the base station wireless communication terminal may not operate the STBC beacon frame and the beacon frame included in the HE extended range SU PPDU together. For example, when the base station wireless communication terminal uses the beacon frame included in the HE extended range SU PPDU, the base station wireless communication terminal may not use the STBC beacon frame. In addition, when the base station wireless communication terminal starts to use the beacon frame included in the HE extended range SU PPDU, the base station wireless communication terminal may stop using the STBC beacon frame.

[0265] The base station wireless communication terminal may use the dual beacon field of the HT operation element to indicate whether to use the STBC beacon frame. In addition, the base station wireless communication terminal may use the dual beacon field of the HT operation element to indicate whether to use the beacon frame included in the HE extended range SU PPDU. When the dual beacon field of the HT operation element signals that either the STBC beacon frame or the beacon frame included in the HE extended range SU PPDU is used, the dual beacon field of the HT operation element may indicate that the other beacon frame is not used. For example, when the dual beacon field of the HE operation element indicates using the STBC beacon frame, the dual beacon field of the HE operation element may indicate not using the beacon frame included in the HE extended range SU PPDU. Therefore, when the dual beacon field of the HE operation element is 1, the dual beacon field of the HE operation element may indicate not using the STBC beacon frame.

[0266] A wireless communication terminal may transmit a single MPDU or an aggregated MPDU (A-MPDU) as the physical layer service data unit (PSDU) of a PPDU. In this case, the wireless communication terminal is capable of aggregating multiple MPDUs to generate an aggregated MAC protocol data unit (A-MPDU). The wireless communication terminal can increase the transmission efficiency by transmitting an A-MPDU instead of dividing multiple MPDUs into multiple PPDUs and transmitting multiple PPDUs. Reference will be made to Figure 35 describe the specific format of the A-MPDU.

[0267] Figure 35 illustrate the format of an A-MPDU according to an embodiment of the present invention.

[0268] An A-MPDU may include a sequence of one or more A-MPDU subframes and EOF padding. The boundaries between A-MPDU subframes can be distinguished by the MPDU delimiter field. An MPDU may follow the MPDU delimiter field. When an A-MPDU subframe is not the last A-MPDU subframe, the A-MPDU subframe may include padding octets. The wireless communication terminal may set the padding octets such that the length of each A-MPDU subframe is a multiple of 4 octets. The length of the padding subfield included in the last A-MPDU subframe may be 0 to 3 octets.

[0269] The length of the MPDU delimiter field may be 4 octets. The specific format of the MPDU delimiter field may be the same as Figure 35The same as shown in. In this case, the MPDU delimiter field can be in the format of the MPDU delimiter field sent by a non-DMG wireless communication terminal. The MPDU delimiter field can include at least one of an EOF subfield, a reserved subfield, an MPDU length subfield, a CRC subfield, and a delimiter signature subfield. The EOF subfield can be a 1-bit field. The wireless communication terminal sets the MPDU length subfield of the A-MPDU subframe to 0 and sets the EOF subfield to 1, thereby indicating that the corresponding A-MPDU subframe is an EOF padding subframe. Additionally, the wireless communication terminal sets the EOF subfield to 1 and sets the MPDU length subfield to a non-zero value to indicate that the corresponding A-MPDU subframe is a VHT single MPDU or a single MPDU (S-MPDU). A VHT single MPDU or a single MPDU is only one MPDU in the corresponding A-MPDU. In other cases, the wireless communication terminal can set the EOF field to 0. The MPDU length subfield can indicate the length of the MPDU including the A-MPDU subframe in octets. When the A-MPDU subframe does not include an MPDU, the wireless communication terminal sets the MPDU length field to 0. The CRC subfield can include a 16-bit CRC value included in the MPDU delimiter field. The CRC field can be an 8-bit field. The delimiter signature subfield can include a set of values for identifying the MPDU delimiter. In this case, the set value can be 0x4E.

[0270] The length of the EOF padding field can be variable. The EOF padding field can include an EOF padding subframe and an EOF padding octet. The EOF padding field can optionally include one or more EOF padding subframes. The MPDU delimiter field can include an MPDU length field and an EOF field. The wireless communication terminal sets the MPDU length subfield of the A-MPDU subframe to 0 and sets the EOF subfield to 1, thereby indicating that the corresponding A-MPDU subframe is an EOF padding subframe. The length of the EOF padding octet subfield can be 0 to 3 octets.

[0271] As described above, the wireless communication terminal can signal information about the A-MPDU subframe through the value of the EOF field. In this case, the wireless communication terminal can configure the A-MPDU according to the following rules.

[0272] - An A-MPDU subframe in which the EOF subfield is set to 0 in the A-MPDU does not come after an A-MPDU subframe in which the EOF subfield is set to 1.

[0273] - An A-MPDU subframe in which the EOF subfield is set to 1 and the MPDU length subfield is set to 0 in the A-MPDU does not come before an A-MPDU subframe including a VHT single MPDU.

[0274] In addition, the wireless communication terminal may set a predetermined value in the EOF subfield and request an immediate response to the MPDUs included in the A-MPDU. Specifically, when transmitting a frame via an A-MPDU or a multi-TID A-MPDU, the wireless communication terminal transmitting the PPDU requests an immediate response by setting the Ack policy field of the QoS data frame or QoS null frame, transmitting a specific type of frame (e.g., an action frame, a BAR frame, or a MU-BAR frame), or setting the EOF subfield to a predetermined value.

[0275] A multi-TID A-MPDU represents an MPDU generated by associating multiple MPDUs having different traffic identifiers (TIDs). Specifically, a multi-TID A-MPDU may be an A-MPDU including multiple QoS data frames having different TIDs. The wireless communication terminal may use the value of a subfield of the MPDU delimiter field included in the multi-TID A-MPDU to request a specific type of response to the MPDUs included in the A-MPDU subframe. Specifically, when the wireless communication terminal generates a multi-TID A-MPDU, the wireless communication terminal may set the MPDU length subfield of the MPDU delimiter field to a non-zero value and set the value of the EOF subfield to 0 to request immediate ACK frame transmission for the QoS data frame or action frame included in the A-MPDU subframe corresponding to the MPDU delimiter field. In addition, the wireless communication terminal may set multiple discontinuous MPDU delimiter fields, where the EOF subfield is 1 and the MPDU length field has a non-zero value, to request an ACK for the MPDUs included in each of the multiple MPDU delimiter fields. In addition, the wireless communication terminal may set multiple discontinuous MPDU delimiter fields, where the EOF subfield is 0 and the MPDU length field has a non-zero value to request a block Ack for the MPDUs included in each of the multiple MPDU delimiter fields. The wireless communication terminal may aggregate A-MPDUs by combining an A-MPDU subframe including an MPDU delimiter field with an EOF subfield of 1 and an MPDU length subfield of non-zero and an A-MPDU subframe including an MPDU delimiter field where the EOF subfield is 0 and the MPDU length subfield is not 0. In addition, the wireless communication terminal may non-continuously aggregate A-MPDU subframes having the same TID to generate a multi-TID A-MPDU.

[0276] The wireless communication terminal receiving the multi-TID A-MPDU may transmit a multi-STA block Ack in response to the multi-TID A-MPDU. In this case, the multi-STA block Ack may include the following per-STA information fields.

[0277] - Each STA information field that indicates an ACK for successfully receiving an MPDU corresponding to an MPDU length field with an EOF sub-field value of 1 has a non-zero length (in this case, the TID value of the MPDU can indicate the TID of a QoS data frame or a QoS null frame. Additionally, the TID value of the MPDU can be 15, which represents an action frame.)

[0278] - Each STA information field that indicates a block Ack for successfully receiving an MPDU corresponding to an MPDU length field with an EOF sub-field value of 0 has a non-zero length (in this case, the TID value of the MPDU can be the TID value of a QoS data frame.)

[0279] Reference will be made to Figure 36 describe the specific format of the block Ack.

[0280] Figure 36 show the specific format of the block Ack according to an embodiment of the present invention.

[0281] The block Ack frame can include at least one of a frame control field, a duration field, an RA field, a TA field, a BA control field, a BA information field, and an FCS field. The frame control field, the duration field, the RA field, and the TA field correspond to the MAC header. When the block Ack frame is not a multi-STA block Ack variant, the wireless communication terminal can set the RA field to the TA field of the frame requesting the block Ack frame. Additionally, when the block Ack frame is not a multi-STA block Ack variant, the wireless communication terminal can set the RA field to the address of the wireless communication terminal that transmits the data / management frame that is the ACK for the block Ack frame.

[0282] When the block Ack frame is: the multi-STA block Ack frame is a multi-STA block Ack variant and the value of the AID subfield of each STA information subfield included in the multi-STA block Ack variant is two or more, the wireless communication terminal may set the RA field to a broadcast address. When the block Ack frame is: the multi-STA block Ack frame is a multi-STA block Ack variant and the value of the AID subfield of each STA information subfield included in the multi-STA block Ack variant is 1, the wireless communication terminal may set the RA field to the address of the wireless communication terminal that requests the block Ack, or it may set it to a broadcast address. When the block Ack frame is: the multi-STA block Ack frame is a multi-STA block Ack variant and the value of the AID subfield of each STA information subfield included in the multi-STA block Ack variant is 1, the wireless communication terminal may set the RA field to the address of the wireless communication terminal that requests the block Ack, or it may set it to the address of the wireless communication terminal that transmits the data / management frame as an ACK with the block Ack frame. Additionally, when the value of the AID subfield of each STA information subfield included in the multi-STA block Ack variant is 1, the multi-STA block Ack variant may include only one AID subfield of each STA information subfield or multiple AID subfields of each STA information subfield with the same value.

[0283] Additionally, the BA control field may include at least one of a BA Ack measurement subfield, a BA type subfield, a TID_INFO subfield, and a reserved subfield, as Figure 36 shown. The BA type subfield may include at least one of an existing multi-TID subfield, a compressed bitmap subfield, and a GCR subfield. Specifically, B1 of the BA type may be the same as the existing multi-TID subfield. Additionally, B2 of the BA type may be the same as the existing compressed bitmap subfield. Additionally, B3 of the BA type may be the same as the existing GCR subfield.

[0284] In a particular embodiment, the wireless communication terminal may use the BA type subfield to signal a type of block Ack frame. The wireless communication terminal may set the BA type subfield to a predetermined value to indicate that the block Ack frame is a multi-STA block Ack variant. For example, the wireless communication terminal may set B1 - B4 of the BA type subfield to 1101 to indicate that the block Ack frame is a multi-STA block Ack variant. The block Ack frame being a multi-STA block Ack variant may be referred to as a multi-STA block Ack frame. Furthermore, the wireless communication terminal may use the BA type subfield to indicate whether the block Ack frame is a basic block Ack, a compressed block Ack, a GLK-GCR block Ack, a GCR block Ack, an extended compressed block Ack, a multi-TID block Ack, or a multi-STA block Ack.

[0285] In addition, the information indicated by the TID_INFO subfield may vary according to the block Ack frame variant type. Specifically, the information indicated by the TID_INFO subfield may vary according to the type of the block Ack frame. When the block Ack frame is a multi-STA block Ack, the TID_INFO subfield may be a reserved field.

[0286] In addition, the information indicated by the BA information field may vary according to the block Ack frame variant type. Specifically, when the block Ack frame is a multi-STA block Ack variant, the BA information field may include Figure 37 one or more per-STA information subfields. The specific format of the per-STA information subfields will be described in detail with reference to Figure 37 In this specification, receiving an MPDU / frame may refer to successfully receiving an MPDU or frame. Specifically, if the value of the frame check sequence (FCS) obtained based on the received MPDU / frame is equal to the value of the FCS field, the wireless communication terminal may determine that the MPDU / frame has been successfully received.

[0287] Figure 37 Shows per-STA information subfields according to an embodiment of the present invention.

[0288] The BA information field of the multi-STA block Ack may include one or more per-STA information fields.

[0289] The per-STA information subfield may include a per-AID TID information subfield. The per-AID TID information subfield may include at least one of an AID subfield, an Ack type subfield, and a TID subfield. When a multi-STA block Ack frame is to be sent to a wireless communication terminal other than the base station wireless communication terminal, the wireless communication terminal may set the AID subfield to the 11 least significant bits of the AID of the corresponding wireless communication terminal. When a multi-STA block Ack frame is to be sent to a wireless communication terminal other than the base station wireless communication terminal, the wireless communication terminal may set the AID subfield to the AID of the corresponding wireless communication terminal. When it is intended to send a multi-STA block Ack frame to the base station wireless communication terminal, the wireless communication terminal may set the AID subfield to 0.

[0290] A multi-STA block Ack frame may include multiple per-STA information subfields, where the values of the AID subfields are the same. In this case, the values of the TID subfields of the multiple per-STA information subfields may be different from each other.

[0291] The TID subfield indicates the TID of the frame for which the per-AID TID information subfield ACKs. When the per-AID TID information subfield of the multi-STA block Ack variant ACKs a management frame, the wireless communication terminal may set the TID subfield to 15.

[0292] In addition, the Ack type subfield may indicate whether a Block Ack start sequence control subfield and a Block Ack bitmap subfield exist in each STA information subfield corresponding to the Ack type subfield. This will be described in more detail with reference to Figure 38 this.

[0293] Figure 38 Illustrates the context of each STA information subfield according to an embodiment of the present invention.

[0294] When the Ack type subfield is 1 and the value of the TID subfield of each AID TID information subfield is less than or equal to 8 or 15, the Ack type subfield and the TID subfield may indicate that the Block Ack start sequence control subfield and the Block Ack bitmap subfield do not exist. In this case, each STA information subfield corresponding to the Ack type field may be an ACK, that is, a single MPDU successfully received as indicated by the TID subfield of each AID TID information subfield.

[0295] In addition, when the Ack type subfield is 1 and the value of the TID subfield of each AID TID information subfield is 14, the Ack type subfield and the TID subfield may indicate that the Block Ack start sequence control subfield and the Block Ack bitmap subfield do not exist. In this case, each STA information subfield corresponding to the Ack type field may be an ACK, that is, all MPDUs of the A-MPDU including the frame indicated by the TID subfield of each AID TID information subfield are successfully received.

[0296] In addition, when the Ack type subfield is 0, the Ack type subfield may indicate the existence of a Block Ack start sequence control subfield and a Block Ack bitmap subfield. In addition, the specific context of each STA information subfield may be the same as that shown in Figure 38 this.

[0297] This will be described in more detail with reference to Figures 39 to 40 a specific method for a wireless communication terminal to receive a multi-TID A-MPDU to generate a multi-STA Block Ack frame. For ease of explanation, the wireless communication terminal that transmits the multi-TID A-MPDU is referred to as the multi-TID A-MPDU transmitter, and the wireless communication terminal that receives the multi-TID A-MPDU is referred to as the multi-TID A-MPDU receiver.

[0298] Figures 39 to 40 Illustrates the A-MPDU configuration according to an embodiment of the present invention.

[0299] As described above, a wireless communication terminal may aggregate A-MPDUs by combining A-MPDU subframes including an MPDU delimiter field in which the EOF subfield is 1 and the MPDU length subfield is not 0 and A-MPDU subframes including an MPDU delimiter field in which the EOF subfield is 0 and the MPDU length subfield is not 0. In addition, the wireless communication terminal may non-continuously aggregate A-MPDU subframes having the same TID to generate a multi-TID A-MPDU. When the EOF subfield of the MPDU delimiter field is 1 and the MPDU length subfield is not 0, using each AID TID information field in which the block Ack start sequence control field and the block Ack bitmap field block are omitted, a multi-TID A-MPDU receiver may ACK for the MPDU corresponding to the MPDU delimiter field. Additionally, when the EOF subfield of the MPDU delimiter field is 0 and the MPDU length subfield is not 0, using each AID TID information field including both the block Ack start sequence control field and the block Ack bitmap field, a multi-TID A-MPDU receiver may ACK for the MPDU corresponding to the MPDU delimiter field. For a valid multi-STA block Ack frame configuration, when a multi-TID A-MPDU transmitter generates a multi-TID A-MPDU, the multi-TID A-MPDU transmitter may limit the number of MPDUs corresponding to the TID requesting an ACK other than a block Ack to one MPDU per TID. Specifically, when the multi-TID A-MPDU transmitter aggregates a multi-TID A-MPDU, the multi-TID A-MPDU transmitter may add the MPDU corresponding to the MPDU delimiter field in which the EOF subfield is 1 and the MPDU length subfield is not 0 to the multi-TID A-MPDU, and then may not add an MPDU having the same TID as the TID of the corresponding MPDU to the multi-TID A-MPDU.

[0300] In addition, when the MPDU included in any one A-MPDU subframe corresponds to a specific TID among the MPDUs included in the multi-TID A-MPDU, the multi-TID A-MPDU transmitter may set the EOF subfield of the A-MPDU subframe to 1. When the MPDU included in any one A-MPDU subframe is the only MPDU among the MPDUs included in the multi-TID A-MPDU that corresponds to a specific TID where the value of the MPDU length field is not 0, the multi-TID A-MPDU transmitter may set the EOF subfield of the A-MPDU subframe to 1. In addition, when the MPDU included in any one A-MPDU subframe does not correspond to a specific TID among the MPDUs included in the multi-TID A-MPDU, the multi-TID A-MPDU transmitter may set the EOF subfield of the A-MPDU subframe to 0. When the MPDU included in any one A-MPDU subframe is not the only MPDU among the MPDUs included in the multi-TID A-MPDU that corresponds to a specific TID where the value of the MPDU length field is not 0, the multi-TID A-MPDU transmitter may set the EOF subfield of the A-MPDU subframe to 0.

[0301] In a specific embodiment, when the multi-TID A-MPDU transmitter uses a PPDU in a predetermined format for multi-TID A-MPDU transmission, the multi-TID A-MPDU transmitter may set the EOF subfield according to the embodiment. As described above. For example, when the multi-TID A-MPDU transmitter uses a non-conventional PPDU for the transmission of the multi-TID A-MPDU, the multi-TID A-MPDU transmitter may set the EOF subfield according to the above embodiment. In this case, the non-conventional PPDU may represent the PPDU format described in Figure 28 the reference.

[0302] A multi-TID A-MPDU receiver can generate a multi-STA block Ack frame as follows. When the multi-TID A-MPDU receiver receives all the MPDUs corresponding to the MPDU delimiter field where the EOF subfield is 0 and the MPDU length subfield is not 0, the multi-TID A-MPDU receiver can determine that all the MPDUs in the multi-TID A-MPDU for which a block Ack is requested have been received. In addition, when the EOF subfield of the MPDU delimiter field corresponding to all the MPDUs not received by the multi-TID A-MPDU receiver is 1 and the MPDU length subfield is not 0, the multi-TID A-MPDU receiver can determine that all the MPDUs for which a block Ack is requested and included in the multi-TID A-MPDU have been received. When the EOF subfield of the MPDU delimiter field corresponding to all the MPDUs not received by the multi-TID A-MPDU receiver is 1, the multi-TID A-MPDU receiver can determine that all the MPDUs for which a block Ack is requested and included in the multi-TID A-MPDU have been received.

[0303] According to the following embodiments, the multi-TID A-MPDU receiver can determine that the EOF subfield of the MPDU delimiter field corresponding to the non-received MPDU is 1. In an A-MPDU, when the A-MPDU subframe with the EOF subfield set to 0 is restricted from being located after the A-MPDU subframe with the EOF subfield set to 1, the multi-TID A-MPDU receiver can determine that the EOF subfield of the MPDU delimiter field corresponding to the non-received MPDU is 1 according to the following embodiments. When the multi-TID A-MPDU receiver does not receive the MPDUs included in the A-MPDU subframe located after the A-MPDU subframe including the MPDU delimiter field with the EOF subfield being 1, the multi-TID A-MPDU receiver can determine that the MPDUs corresponding to the MPDU delimiter field with the EOF subfield being 1 have not been received. In another specific embodiment, when the multi-TID A-MPDU receiver receives the MPDU delimiter field and does not receive the MPDU corresponding to the MPDU delimiter field, the multi-TID A-MPDU receiver can check the value of the EOF subfield of the MPDU delimiter field and determine whether the multi-TID A-MPDU receiver has not received the MPDU corresponding to the MPDU delimiter field with the EOF subfield being 1.

[0304] Receiving all the MPDUs included in the multi-TID A-MPDU and requesting a block Ack can mean receiving all the MPDUs of the TID having the MPDUs corresponding to the MPDU delimiter field where the EOF subfield is 0 and the MPDU length subfield is not 0 and which is included in the multi-TID A-MPDU.

[0305] When a multi-TID A-MPDU receiver receives all MPDUs included in a multi-TID A-MPDU and requesting a block Ack, with respect to the MPDU corresponding to the MPDU delimiter field where the EDU subfield is 0 and the MPDU length subfield is not 0, using each AID TID information field where the block Ack start sequence control field and the block Ack bitmap field blocks are omitted, the multi-TID A-MPDU receiver can ACK. Specifically, with respect to the MPDU corresponding to the MPDU delimiter field where the EDU subfield is 0 and the MPDU length subfield is not 0, using each AID TID information field, the multi-TID A-MPDU receiver can ACK, where the Ack type subfield is set to 1. In these embodiments, the multi-TID A-MPDU receiver can set the TID subfield of each AID TID information field to the TID of the received MPDU. In a particular embodiment, the multi-TID A-MPDU receiver can send a multi-STA block Ack frame to the multi-TID A-MPDU transmitter, which indicates that the multi-TID A-MPDU receiver has received all MPDUs of the TID indicated by the TID subfield of each AID TID information field, and includes a multi-STA block Ack frame that includes each AID TID information where the block Ack start sequence control subfield and the block Ack bitmap subfield are omitted. In this case, each AID TID information field can also include an indicator that indicates that all MPDUs of the TID indicated by the TID subfield of each AID TID information field have been received.

[0306] The multi-TID A-MPDU receiver sends the generated multi-STA block Ack frame to the multi-TID A-MPDU transmitter. When the value of the TID subfield of each AID TID information field is from 0 to 7 and the value of the Ack type subfield is 1, the multi-TID transmitter can determine that the multi-STA block Ack frame including each AID TID information field is included in the multi-TID A-MPDU requesting the multi-STA block Ack frame, and the multi-TID receiver has received a single MPDU or all MPDUs corresponding to the TID indicated by the TID subfield.

[0307] In Figure 39In an embodiment, the MPDUs not received by the multi-TID A-MPDU receiver are the MPDUs corresponding to the MPDU delimiter field where the EOF subfield is 1 and the MPDU length subfield is not 0. Thus, with respect to the MPDUs corresponding to the MPDU delimiter field where the EOF subfield is 0 and the MPDU length subfield is not 0, using the per-AID TID information field, the multi-TID A-MPDU receiver performs ACK, omitting the Block Ack start sequence control field and the Block Ack bitmap field in the per-AID TID information field. Specifically, the multi-TID A-MPDU receiver may send a multi-STAA Block Ack including the Block Ack start sequence control field and the per-AID TID information field to the multi-TID A-MPDU transmitter, where the Block Ack bitmap field is omitted.

[0308] In Figure 40 an embodiment, the A-MPDU subframe in which the EOF subfield is set to 0 in the A-MPDU is restricted from being located after the A-MPDU subframe in which the EOF subfield is set to 1. The multi-TID A-MPDU receiver does not receive the MPDU delimiter field corresponding to the non-received MPDU. Since the value of the EOF subfield of the MPDU delimiter field corresponding to the MPDU before the non-received MPDU is 1, the multi-TID A-MPDU receiver can determine that the value of the EOF subfield of the non-received MPDU delimiter is 1. Thus, the multi-TID A-MPDU receiver can determine that the multi-TID A-MPDU receiver has received all the MPDUs corresponding to the MPDU delimiter field where the EDU subfield is 0 and the MPDU length subfield is not 0. With respect to the MPDUs corresponding to the MPDU delimiter field where the EOF subfield is 0 and the MPDU length subfield is not 0, using the per-AID TID information field, the multi-TID A-MPDU receiver performs ACK, omitting the Block Ack start sequence control field and the Block Ack bitmap field in the per-AID TID information field. Specifically, the multi-TID A-MPDU receiver may send a multi-STA Block Ack including the Block Ack start sequence control field and the per-AID TID information field where the Block Ack bitmap field is omitted to the multi-TID A-MPDU transmitter.

[0309] Figure 41 shows the operation of a wireless communication terminal according to an embodiment of the present invention.

[0310] The wireless communication terminal receives a trigger frame that triggers random access (S4101). The wireless communication terminal performs random access based on the trigger frame (S4103). In this case, the wireless communication terminal may perform random access according to the above OBO procedure. Specifically, according to the reference Figures 6 to 26In the described embodiment, the wireless communication terminal may perform random access.

[0311] The wireless communication terminal may set an integer selected from 0 to a value equal to or less than the OFDMA contention window (OCW) as a counter for random access. In this case, the counter for random access may be the above-mentioned OBO counter. In addition, when the wireless communication terminal attempts random access for the first time, the wireless communication terminal receives the OBO-related parameters signaled by the base station to the wireless communication terminal, or when the wireless communication terminal successfully transmits through random access, the wireless communication terminal may initialize the OBO process. The initialization of the OBO process may include at least one of the initialization of the counter for random access and the initialization of the OCW. In addition, when the wireless communication terminal initializes the OCW, the wireless communication terminal may set the OCW to OCWmin. When the transmission of random access by the wireless communication terminal fails, the wireless communication terminal may update the value of the OCW to (2×OCW + 1). In this case, the wireless communication terminal selects a random integer from the updated OCW and sets the selected integer as the counter for random access. In addition, when the value of the OCW reaches OCWmax, even if the transmission of random access by the wireless communication terminal fails, the wireless communication terminal may maintain the OCW as OCWmax.

[0312] The trigger frame may indicate random access using one or more RUs allocated for random access. Specifically, the trigger frame may indicate the allocation of one or more RUs for random access. In this case, the wireless communication terminal may decrement the value of the counter for random access based on one or more RUs allocated for random access. When the trigger frame indicates the uplink transmission of the wireless communication terminal, the wireless communication terminal may not decrement the value of the counter based on the trigger frame. The specific operation of the wireless communication terminal may be the same as the operation in the embodiment described with reference to Figure 26 described embodiment.

[0313] In this case, as described above, an RU is a group of multiple subcarriers available for uplink transmission and downlink transmission.

[0314] The wireless communication terminal may decrement the value of the counter for random access based on the capability of the wireless communication terminal and one or more RUs allocated for random access. When the value of the counter for random access is 0 or reaches 0, the wireless communication terminal may randomly select one or more RUs allocated for random access.

[0315] The wireless communication terminal may perform a random access operation according to the capability of the wireless communication terminal. In this case, the wireless communication terminal may operate as follows.

[0316] The wireless communication terminal may decrement the value of the counter for random access by the number of RUs allocated for random access among one or more RUs through which the wireless communication terminal can send a TB PPDU according to the capabilities of the wireless communication terminal. The capabilities of the wireless communication terminal may include capabilities related to the bandwidth through which the wireless communication terminal can perform transmissions. Additionally, the capabilities of the wireless communication terminal may include the capability of the length of the padding field included in the TB PPDU. Additionally, the capabilities of the wireless communication terminal may include the capability of the modulation and coding scheme for which the wireless communication terminal can perform transmissions. The capabilities of the wireless communication terminal may include the capabilities of the wireless communication terminal related to at least one of dual carrier modulation (DCM), the number of spatial streams, the length of the guard interval (GI), the type of long training field (LTF), spatial block coding (STBC), and transmission power.

[0317] When the value of the counter for random access is 0 or reaches 0, the wireless communication terminal may randomly select any one of the RUs allocated for random access and may send a TB PPDU according to the capabilities of the wireless communication terminal. When there is no RU through which the wireless communication terminal can send a TB PPDU among the one or more RUs allocated for random access, the wireless communication terminal may maintain the counter for random access at 0. Operations related to the capabilities of the wireless communication terminal may be the same as the operations of the wireless communication terminal in the Figures 14 to 21 embodiment.

[0318] The wireless communication terminal may be a wireless communication terminal non-associated with the base station wireless communication terminal that sends a trigger frame. In this case, the wireless communication terminal may operate as follows.

[0319] The wireless communication terminal may set the OCW minimum value, which is a parameter indicating the minimum value of the OCW, to a predetermined value that is the default value of the OCW minimum value, and set the OCW maximum value, which is a parameter indicating the maximum value of the OCW, to a predetermined value that is the default value of the OCW maximum value. In this case, the value predetermined as the default value of the OCW minimum value and the value predetermined as the default value of the OCW maximum value may not be values specified by the base station wireless communication terminal. As described above, the OCW minimum value may be the OCWmin as described above. Additionally, the OCW maximum value may be the OCWmax as described above.

[0320] When a wireless communication terminal communicates with a base station wireless communication terminal that sends a trigger frame and another base station wireless communication terminal, the wireless communication terminal may initialize parameters for random access to the other wireless communication terminal. The parameters for random access may include a counter for random access, a minimum OCW, and a maximum OCW, which is a parameter indicating the maximum value of the OCW. When the wireless communication terminal communicates with the base station wireless communication terminal that sends the trigger frame, the wireless communication terminal may set the minimum OCW and the maximum OCW according to the information received from the base station wireless communication terminal that sends the trigger frame, and when the wireless communication terminal communicates with another base station wireless communication terminal, the wireless communication terminal may set the minimum OCW and the maximum OCW according to the information received from the other base station wireless communication terminal. In this case, the information received from the base station wireless communication terminal that sends the trigger frame or the base station wireless communication terminal through wireless communication may be information about the OBO parameter. Specifically, the information about the OBO parameter may be the above UORA parameter set element. The wireless communication terminal may maintain OBO-related parameters and OBO processes for each base station wireless communication terminal. In a specific embodiment, the wireless communication terminal may set OBO-related parameters for each base station wireless communication terminal. Specifically, the wireless communication terminal may set OBO-related parameters for each base station wireless communication terminal based on the information about the OBO-related parameters received from each base station wireless communication terminal. The specific operations of a wireless communication terminal not associated with the base station wireless communication terminal may be the same as those in the embodiment described with reference to Figures 21 to 25 The same as those in the embodiments described.

[0321] The wireless communication terminal may be a wireless communication terminal associated with the base station wireless communication terminal that sends the trigger frame. In addition, the base station wireless communication terminal that sends the trigger frame may belong to a multi-BSSID set. In this case, the wireless communication terminal may operate as follows.

[0322] The minimum and maximum values of the OCW can be set based on information received from other base station wireless communication terminals belonging to a multi - BSSID set to which the base station wireless communication terminal transmitting the trigger frame belongs. In this case, the other base station wireless communication terminal can be a base station wireless communication terminal operating the BSS corresponding to the BSSID transmitted by the multi - BSSID set. In addition, the wireless communication terminal may not decrement the value of the counter based on a trigger frame transmitted from another base station wireless communication terminal. The other base station wireless communication terminal can be a base station wireless communication terminal operating the BSS corresponding to the BSSID transmitted by the multi - BSSID set. The information received from other base station wireless communication terminals may not be only the information indicated in the signaling field allocated to the BSS including the wireless communication terminal. Specifically, the signaling field allocated only to the BSS including the wireless communication terminal may indicate the above - mentioned non - transmitted profile. In this case, the information can be the above - mentioned UORA parameter set element. When using a multi - BSSID set, specific operations of the wireless communication terminal can be the same as the specific operations in the embodiment described with reference to Figures 11 to 13 The specific operations in the described embodiments are the same.

[0323] The wireless communication terminal can attempt to use the selected RU to perform transmission to the base station wireless communication terminal. In this case, the wireless communication terminal can determine whether the selected RU is idle, and when the selected RU is idle, can send the pending frame of the base station wireless communication terminal to the base station wireless communication terminal through the selected RU. Additionally, when the wireless communication terminal determines that the corresponding RU is busy through either physical carrier sensing or virtual carrier sensing, the wireless communication terminal determines that the corresponding RU is busy. Physical carrier sensing can include Clear Channel Assessment (CCA). When it is determined that the RU selected by the wireless communication terminal is busy, the wireless communication terminal can maintain the OBO counter at 0 without sending the pending frame to the base station wireless communication.

[0324] Although the present invention is described by taking wireless LAN communication as an example, the present invention is not limited thereto and can be applied to other communication systems such as cellular communication. Additionally, although the methods, devices, and systems of the present invention are described according to specific embodiments of the present invention, some or all components or operations of the present invention can be implemented using a computer system with a general - purpose hardware architecture.

[0325] The features, structures, and effects described in the above - mentioned embodiments are included in at least one embodiment of the present invention and are not necessarily limited to one embodiment. In addition, those skilled in the art can combine or improve the features, structures, and effects shown in each embodiment in other embodiments. Therefore, it should be understood that the content related to such combination and improvement is included within the scope of the present invention.

[0326] Although the present invention is mainly described based on the above embodiments, it is not limited thereto. However, those skilled in the art will understand that various changes and improvements can be made without departing from the spirit and scope of the present invention. For example, each component specifically shown in the embodiments can be modified and implemented. It should be understood that the differences related to such modifications and applications are included within the scope of the present invention defined by the appended claims.

Claims

1. A wireless communication terminal that wirelessly communicates with a base station wireless communication terminal, the wireless communication terminal comprising: a transceiver; and a processor, wherein the processor is configured to: set an integer selected from a range from 0 to a value equal to or less than the value of an Orthogonal Frequency Division Multiple Access (OFDMA) contention window (OCW) as a counter for random access, use the transceiver to receive from the base station wireless communication terminal a trigger frame for triggering the random access using one or more resource units (RUs) allocated for the random access, decrement the value of the counter by the number of RUs through which the wireless communication terminal can transmit a trigger-based physical layer protocol data unit (PPDU), wherein the number of RUs is determined according to the capabilities of the wireless communication terminal among the one or more RUs for the random access, when the value of the counter is 0 or reaches 0, randomly select any one of the RUs through which the wireless communication terminal can transmit a trigger-based PPDU, and attempt a transmission to the base station wireless communication terminal using the selected RU, wherein when the trigger frame schedules an uplink transmission of the wireless communication terminal, the wireless communication terminal maintains the value of the counter, wherein the RU is a group of multiple subcarriers available for uplink transmission and downlink transmission.

2. The wireless communication terminal according to claim 1, wherein when the wireless communication terminal is a wireless communication terminal non-associated with the base station wireless communication terminal, the processor is configured to: set the OCW minimum value, which is a parameter indicating the minimum value of the OCW, to a value pre-determined as the default value of the OCW minimum value, and set the OCW maximum value, which is a parameter indicating the maximum value of the OCW, to a value pre-determined as the default value of the OCW maximum value, wherein the value pre-determined as the default value of the OCW minimum value and the value pre-determined as the default value of the OCW maximum value are not values specified by the base station wireless communication terminal.

3. The wireless communication terminal according to claim 1, wherein when the wireless communication terminal is a wireless communication terminal non-associated with the base station wireless communication terminal and the wireless communication terminal communicates with a different base station wireless communication terminal different from the base station wireless communication terminal, the processor is configured to initialize parameters for the random access to the different base station wireless communication terminal, wherein the parameters for the random access include the counter, the OCW minimum value, which is a parameter indicating the minimum value of the OCW, and the OCW maximum value, which is a parameter indicating the maximum value of the OCW.

4. The wireless communication terminal according to claim 3, wherein when the wireless communication terminal is a wireless communication terminal non-associated with the base station wireless communication terminal, the processor is configured to: when the wireless communication terminal communicates with the base station wireless communication terminal, set the OCW minimum value and the OCW maximum value according to information received from the base station wireless communication terminal, and When the wireless communication terminal communicates with the different base station wireless communication terminals, set the minimum OCW and the maximum OCW according to the information received from the different base station wireless communication terminals.

5. The wireless communication terminal according to claim 1, wherein, when the wireless communication terminal associates with a basic service set (BSS) corresponding to an unsent BSSID in a multi-basic service set identifier (BSSID) set, the processor is configured to: set an OCW minimum value as a parameter indicating the minimum value of the OCW and an OCW maximum value as a parameter indicating the maximum value of the OCW according to a UL OFDMA-based random access (UORA) parameter set from another base station wireless communication terminal operating on a BSS corresponding to the sent BSSID in the multi-BSSID set, wherein the UORA parameter set includes a parameter related to the counter.

6. The wireless communication terminal according to claim 5, wherein, the processor is configured not to decrement the value of the counter based on a trigger frame sent from the BSS corresponding to the sent BSSID in the multi-BSSID set.

7. The wireless communication terminal according to claim 6, wherein, the UORA parameter set received from the BSS corresponding to the sent BSSID is not the UORA parameter set indicated in a signaling field allocated for the BSS including the wireless communication terminal.

8. A method of operating a wireless communication terminal that wirelessly communicates with a base station wireless communication terminal, the method comprising: setting an integer selected from a range from 0 to a value equal to or less than the value of an orthogonal frequency division multiple access (OFDMA) contention window (OCW) as a counter for random access; receiving from the base station wireless communication terminal a trigger frame for triggering the random access using one or more resource units (RUs) allocated for the random access; decrementing the value of the counter by the number of RUs through which the wireless communication terminal can transmit a trigger-based physical layer protocol data unit (PPDU), wherein the number of RUs is determined according to the capability of the wireless communication terminal among the one or more RUs for the random access, when the value of the counter is 0 or reaches 0, randomly selecting any one of the RUs through which the wireless communication terminal can transmit a trigger-based PPDU, and attempting transmission to the base station wireless communication terminal using the selected RU, wherein when the trigger frame schedules an uplink transmission of the wireless communication terminal, the wireless communication terminal maintains the value of the counter, wherein the RU is a group of multiple subcarriers available for OFDM communication.

9. The method according to claim 8, wherein, when the wireless communication terminal is a wireless communication terminal non-associated with the base station wireless communication terminal, the method further comprises: setting an OCW minimum value as a parameter indicating the minimum value of the OCW to a default value predetermined as the OCW minimum value, and Set the OCW maximum value, which is a parameter indicating the maximum value of the OCW, to a value that is preset as the default value for the OCW maximum value. Among them, the value preset as the default value for the OCW minimum value and the value preset as the default value for the OCW maximum value are not values specified by the base station wireless communication terminal.

Images