Wireless communication method and wireless communication terminal for signaling multi-user packets

Abstract

This invention provides a wireless communication method and a wireless communication terminal for signaling multi-user packets. [Solution] In a wireless communication system, the wireless communication terminal AP200 includes a communication unit and a processor that processes signals transmitted and received via the communication unit. The processor receives an HE MU PPDU (high efficiency multi-user PHY protocol data unit) via the communication unit. The preamble of the HE MU PPDU includes HE-SIG-A (High Efficiency Signal A field) and HE-SIG-B (High Efficiency Signal B field). The processor decodes the received HE MU PPDU based on information obtained from HE-SIG-A, and the configuration of HE-SIG-B is identified based on information obtained from at least one subfield of HE-SIG-A.

Description

Technical Field

[0001] The present invention relates to a wireless communication method and a wireless communication terminal for signaling multi-user packets.

Background Art

[0002] Recently, as the spread of mobile devices has expanded, Wireless LAN (WLAN) technology that can provide fast wireless Internet services to them has been in the spotlight. WLAN technology is a technology that enables mobile devices such as smartphones, smart pads, laptop PCs, portable multimedia players, and embedded devices to be wirelessly connected to the Internet at home, in enterprises, or in specific service-providing areas based on wireless communication technology at short distances.

[0003] Since IEEE (Institute of Electronics Engineers) 802.11 supported the initial WLAN technology using the 2.4 GHz frequency, various technology standards have been put into practical use or are under development. First, IEEE 802.11b uses the frequency of the 2.4 GHz band and supports a communication speed of up to 11 Mbps. IEEE 802.11a, which was commercialized after IEEE 802.11b, uses the frequency of the 5 GHz band instead of the 2.4 GHz band, reducing the impact on interference compared to the rather congested 2.4 GHz band frequency, and using OFDM technology to improve the communication speed up to 54 Mbps. However, IEEE 802.11a has the disadvantage of a shorter communication distance compared to IEEE 802.11b. And IEEE 802.11g uses the same 2.4 GHz band frequency as IEEE 802.11b to implement a maximum communication speed of 54 Mbps and satisfies backward compatibility, receiving considerable attention, but is also superior to IEEE 802.11a in terms of communication distance.

[0004] Furthermore, IEEE 802.11n is a technical standard established to overcome the limitations in communication speed that had been pointed out as a vulnerability in wireless LANs. The purpose of IEEE 802.11n is to increase network speed and reliability and extend the operating range of wireless networks. Specifically, IEEE 802.11n supports high throughput (HT) with a data processing speed of up to 540 Mbps or more, and is based on MIMO (Multiple Inputs and Multiple Outputs) technology, which uses multiple antennas at both the transmitter and receiver ends to minimize transmission errors and optimize data speed. In addition, this standard uses a coding method that transmits multiple duplicate copies to improve data reliability.

[0005] As the proliferation of wireless LANs accelerates and the applications using them diversify, there is a growing need for new wireless LAN systems that can support very high throughput (VHT) higher than the data processing speed supported by IEEE 802.11n. Among these, IEEE 802.11ac supports a wide bandwidth (80MHz to 160MHz) at the 5GHz frequency. Although the IEEE 802.11ac standard is defined only in the 5GHz band, early 11ac chipsets are expected to support operation in the 2.4GHz band for backward compatibility with older 2.4GHz band products. Theoretically, this standard allows for a minimum wireless LAN speed of 1Gbps and a maximum single-link speed of 500Mbps. This is achieved by extending the wireless interface concepts accepted in 802.11n, including wider radio frequency bandwidth (up to 160MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256QAM). Another method for transmitting data using the 60GHz band instead of the conventional 24GHz / 5GHz band is IEEE 802.11ad. IEEE 802.11ad is a transmission standard that uses beamforming technology to provide speeds of up to 7Gbps, making it suitable for streaming large amounts of data and high-bitrate video such as uncompressed HD video. However, the 60GHz frequency band has the disadvantage of being difficult to pass through obstacles, limiting its use to devices in short-range spaces.

[0006] Meanwhile, recent discussions have focused on providing highly efficient and high-performance wireless LAN communication technologies for high-density environments, as the standard for next-generation wireless LANs, starting with 802.11ac and 802.11ad. In other words, in next-generation wireless LAN environments, highly frequency-efficient communication should be provided both indoors and outdoors, given the presence of high-density stations and access points (APs), and a variety of technologies are needed to achieve this. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] As described above, the present invention aims to provide highly efficient / high-performance wireless LAN communication technology in high-density environments. [Means for solving the problem]

[0008] To solve the aforementioned problems, the present invention provides a wireless communication method for a terminal and a wireless communication terminal as described below.

[0009] First, according to an embodiment of the present invention, a wireless communication terminal is provided, comprising a communication unit and a processor that processes signals transmitted and received via the communication unit, wherein the processor receives a HE MU PPDU (high efficiency multi-user PHY protocol data unit) via the communication unit, the preamble of the HE MU PPDU includes HE-SIG-A (High Efficiency Signal A field) and HE-SIG-B (High Efficiency Signal B field), and the processor decodes the received HE MU PPDU based on information obtained from HE-SIG-A, the configuration of HE-SIG-B is identified based on information obtained from at least one subfield of HE-SIG-A.

[0010] Furthermore, according to an embodiment of the present invention, a wireless communication method for a wireless communication terminal is provided, comprising the steps of: receiving an HE MU PPDU; and decoding the received HE MU PPDU based on information obtained from the HE-SIG-A, wherein the preamble of the HE MU PPDU includes HE-SIG-A and HE-SIG-B, and the configuration of the HE-SIG-B is identified based on information obtained from at least one subfield of the HE-SIG-A.

[0011] If the SIG-B compression field of HE-SIG-A indicates full bandwidth MU-MIMO transmission and there is no common field in HE-SIG-B, the configuration of the user-specific field of HE-SIG-B is identified based on information obtained from at least one subfield of HE-SIG-A.

[0012] If the SIG-B compression field of HE-SIG-A instructs full bandwidth MU-MIMO transmission, the configuration of the user identification field of HE-SIG-B is identified based on the number of MU-MIMO users instructed by HE-SIG-A.

[0013] The user fields constituting the user identification field of HE-SIG-B include user fields for MU-MIMO assignment and user fields for non-MU-MIMO assignment. If the number of MU-MIMO users indicates two or more users, the user identification field of HE-SIG-B consists of user fields for MU-MIMO assignment. If the number of MU-MIMO users indicates one user, the user identification field of HE-SIG-B consists of one user field for non-MU-MIMO assignment.

[0014] The user field for MU-MIMO assignment includes a spatial configuration field indicating the total number of spatial streams in the MU-MIMO assignment and the number of spatial streams for each terminal in the MU-MIMO assignment, while the user field for non-MU-MIMO assignment includes an NSTS (Number of Spatial Streams) field.

[0015] The user field for the non-MU-MIMO allocation is the user field of the OFDMA (Orthogonal Frequency Division Multiple Access) allocation infrastructure.

[0016] If the SIG-B compression field of HE-SIG-A indicates full bandwidth MU-MIMO transmission, the number of MU-MIMO users is indicated in HE-SIG-A by the number field of HE-SIG-B symbols.

[0017] The HE-SIG-A includes an uplink / downlink field indicating whether the PPDU is being transmitted uplink or downlink, and at least one subfield of the HE-SIG-A of the PPDU indicates or is set to indicate different information based on the value indicated by the uplink / downlink field.

[0018] If the uplink / downlink field indicates downlink transmission, the specified value in the bandwidth field of HE-SIG-A indicates a preset discontinuous bandwidth; if the uplink / downlink field indicates uplink transmission, the specified value in the bandwidth field of HE-SIG-A indicates a preset narrow bandwidth.

[0019] The aforementioned preset narrow bandwidth includes at least one of the left -106-tone and the right -106-tone.

[0020] If the uplink / downlink fields indicate downlink transmission, the SIG-B compression field of HE-SIG-A indicates whether or not overall bandwidth MU-MIMO transmission is possible as there are no common fields in the HE-SIG-B field. If the uplink / downlink fields indicate uplink transmission, the SIG-B compression field of HE-SIG-A always indicates that there are no common fields in the HE-SIG-B field.

[0021] When the SIG-B compression field of the HE-SIG-A indicates the compression mode of the HE-SIG-B field, if the uplink / downlink field indicates downlink transmission, the number field of the HE-SIG-B symbols of the HE-SIG-A indicates the number information of the MU-MIMO users, and if the uplink / downlink field indicates uplink transmission, the number field of the HE-SIG-B symbols of the HE-SIG-A indicates the number information of the OFDM symbols in the HE-SIG-B field.

Advantages of the Invention

[0022] According to the embodiments of the present invention, the header fields of the physical layer of the wireless LAN packet that supports multi-user simultaneous transmission in indoor and outdoor environments can be efficiently configured.

[0023] According to the embodiments of the present invention, in a contention-based channel access system, the utilization rate of the overall resources can be increased and the performance of the wireless LAN system can be improved.

Brief Description of the Drawings

[0024] [Figure 1] It is a diagram showing a wireless LAN system according to an embodiment of the present invention. [Figure 2] It is a diagram showing a wireless LAN system according to another embodiment of the present invention. [Figure 3] It is a diagram showing the configuration of a station according to an embodiment of the present invention. [Figure 4] It is a diagram showing the configuration of an access point according to an embodiment of the present invention. [Figure 5] It is a diagram schematically showing the process in which a STA sets up a link with an AP. [Figure 6] It is a diagram showing the CSMA (Carrier Sense Multiple Access) / CA (Collision Avoidance) method used in wireless LAN communication. [Figure 7]This diagram shows how to perform a Distributed Coordination Function (DCF) using RTS (Request to Send) frames and CTS (Clear to Send) frames. [Figure 8] This figure shows a multi-user transmission method according to an embodiment of the present invention. [Figure 9] This figure shows a multi-user transmission method according to an embodiment of the present invention. [Figure 10(a)] This figure shows one example of the legacy PPDU format and the non-legacy PPDU format. [Figure 10(b)] This figure shows one example of the legacy PPDU format and the non-legacy PPDU format. [Figure 10(c)] This figure shows one example of the legacy PPDU format and the non-legacy PPDU format. [Figure 11(a)] This figure shows various HE PPDU formats and methods for indicating them according to embodiments of the present invention. [Figure 11(b)] This figure shows various HE PPDU formats and methods for indicating them according to embodiments of the present invention. [Figure 11(c)] This figure shows various HE PPDU formats and methods for indicating them according to embodiments of the present invention. [Figure 11(d)] This figure shows various HE PPDU formats and methods for indicating them according to embodiments of the present invention. [Figure 12] This figure shows an example of the configuration of the HE-SIG-A field in HE PPDU format. [Figure 13] This figure shows the configuration of the HE-SIG-B field according to one embodiment of the present invention. [Figure 14(a)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 14(b)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 14(c)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 14(d)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 15(a)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 15(b)] This figure shows a specific example of transmitting UL MU PPDU to a single STA and AP. [Figure 16(a)] This figure shows the encoding structure and transmission method of HE-SIG-B according to an embodiment of the present invention. [Figure 16(b)] This figure shows the encoding structure and transmission method of HE-SIG-B according to an embodiment of the present invention. [Figure 17] This figure shows a discontinuous channel allocation method according to one embodiment of the present invention. [Figure 18] This figure shows a broadband approach method according to one embodiment of the present invention. [Figure 19] This figure shows one embodiment of a method for exchanging BQRP and BQR signals and signaling for transmitting discontinuous PPDU. [Figure 20] This figure shows another embodiment of a BQR transmission and signaling method for transmitting discontinuous PPDU. [Figure 21] This figure shows the configuration of a BQR according to one embodiment of the present invention. [Modes for carrying out the invention]

[0025] The terminology used herein has been selected to the greatest extent possible from among commonly used terms, taking into account the function of the present invention, although this may differ depending on the intent, conventions, or emergence of new technologies of the articulate persons in the relevant field. In addition, in certain cases, the applicant has arbitrarily selected some terms, in which case their meaning will be described in the description of the relevant invention. Therefore, it should be made clear that the terms used herein are not merely names of terms, but should be interpreted based on the substantive meaning of the terms and the content of this specification as a whole.

[0026] Throughout the specification, when one component is described as being "connected" to another, this includes not only cases where they are "directly connected," but also cases where they are "electrically connected" with other components in between. Furthermore, when a component is described as "containing" a particular component, this means, unless otherwise stated, that it may contain other components rather than excluding them. In addition, limitations such as "greater than or equal to" or "less than or equal to" a specific critical value may be appropriately replaced by "greater than" or "less than" depending on the embodiment.

[0027] This application claims priority based on Korean Patent Applications No. 10-2017-0003147 and No. 10-2017-0008927, and the embodiments and descriptions described in the aforementioned applications that form the basis of the priority claim are included in the detailed description of this application.

[0028] Figure 1 shows a wireless LAN system according to one embodiment of the present invention. The wireless LAN system includes one or more Basic Service Sets (BSS), where a BSS represents a collection of devices that have successfully synchronized and can communicate with each other. Generally, BSSs are classified into infrastructure BSSs and independent BSSs (IBSSs), and Figure 1 shows an infrastructure BSS.

[0029] As shown in Figure 1, the Infrastructure BSS (BSS1, BSS2) includes one or more stations (STA1, STA2, STA3, STA4, STA5), access points (PCP / AP-1, PCP / AP-2) which are stations that provide distribution services, and a distribution system (DS) that connects a large number of access points (PCP / AP-1, PCP / AP-2).

[0030] A Station (STA) is any device that includes Medium Access Control (MAC) and a Physical Layer interface to a wireless medium in accordance with the IEEE 802.11 standard, and in a broad sense includes not only non-AP stations but also all access points (APs). In this specification, "terminal" is used to refer to non-APs, APs, or both. A station for wireless communication includes a processor and a communication unit, and depending on the embodiment, further includes a user interface unit and a display unit, etc. The processor generates frames to be transmitted over the wireless network or processes frames received over the wireless network, and performs various other processing for controlling the station. The communication unit is functionally connected to the processor and sends and receives frames over the wireless network for the station. In this invention, "terminal" is used as a term that includes user equipment (UE).

[0031] An Access Point (AP) is an individual device that provides connectivity to a distribution system (DS) via a wireless medium for stations associated with it. In infrastructure BSS, communication between non-AP stations is generally conducted via APs, however, direct communication is possible between non-AP stations if a direct link is configured. In this invention, AP is used as a concept that includes PCP (Personal BSS Coordination Point), but in a broader sense, it includes all concepts such as central controllers, base stations (BS), node B, BTS (Base Transceiver System), or site controllers. In this invention, AP is also referred to as a base wireless communication terminal, but in a broader sense, base wireless communication terminal is used as a term that includes APs, base stations, eNBs (eNodeBs), and transmission points (TPs). Furthermore, base wireless communication terminals include various forms of wireless communication terminals that allocate and schedule communication medium resources in communication with multiple wireless communication terminals.

[0032] Multiple infrastructure BSSs are connected to each other via a distribution system DS. In this case, multiple BSSs connected via the distribution system are called an Extended Service Set (ESS).

[0033] Figure 2 shows an independent BSS, which is a wireless LAN system according to another embodiment of the present invention. In the embodiment of Figure 2, redundant explanations are omitted for parts that are the same as or corresponding to the embodiment of Figure 1.

[0034] As shown in Figure 2, BSS3 is an independent BSS and does not include APs, so all stations (STA6, STA7) are not connected to APs. An independent BSS is not allowed to connect to a distribution system and forms a self-contained network. In an independent BSS, each station (STA6, STA7) is directly connected to one another.

[0035] Figure 3 is a block diagram showing the configuration of station 100 according to one embodiment of the present invention. As shown, station 100 according to the embodiment of the present invention includes a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.

[0036] First, the communication unit 120 transmits and receives wireless signals such as wireless LAN packets and is built into or externally mounted on the station 100. According to one embodiment, the communication unit 120 includes at least one communication module that utilizes different frequency bands. For example, the communication unit 120 includes communication modules for different frequency bands such as 2.4 GHz, 5 GHz, and 60 GHz. According to one embodiment, the station 100 includes a communication module that utilizes a frequency band of 6 GHz or higher and a communication module that utilizes a frequency band of 6 GHz or lower. Each communication module performs wireless communication with an AP or external station according to the wireless LAN standard of the frequency band supported by the communication module. Depending on the performance and requirements of the station 100, the communication unit 120 may operate only one communication module at a time or operate multiple communication modules together simultaneously. When the station 100 includes multiple communication modules, each communication module may be provided in an independent form, or multiple modules may be integrated into a single chip. In an embodiment of the present invention, the communication unit 120 represents an RF (Radio Frequency) communication module that processes RF signals.

[0037] Next, the user interface 140 includes various forms of input / output means provided in the station 100. In other words, the user interface unit 140 receives user input using various input means, and the processor 110 controls the station 100 based on the received user input. The user interface unit 140 also outputs based on instructions from the processor 110 using various output means.

[0038] Next, the display unit 150 outputs an image to the display screen. The display unit 150 outputs various display objects, such as content generated by the processor 110 or user interfaces based on control instructions from the processor 110. The memory 160 stores control programs used by the station 100 and various data associated with them. Such control programs include connection programs necessary for the station 100 to connect with APs or external stations.

[0039] The processor 110 of the present invention executes various instructions or programs and processes data within the station 100. The processor 110 also controls each unit of the station 100 and controls the transmission and reception of data between units. According to an embodiment of the present invention, the processor 110 executes a program for connection with the AP stored in the memory 160 and receives a communication setup message transmitted by the AP. The processor 110 also reads information regarding the priority conditions of the station 100 contained in the communication setup message and requests a connection to the AP based on the priority conditions of the station 100. The processor 110 of the present invention may refer to the main control unit of the station 100, or, depending on the embodiment, may refer to a control unit for individually controlling a part of the station 100's configuration, such as the communication unit 120. In other words, the processor 110 may be a modem or a modulator and / or demodulator that modulates and demodulates the wireless signals transmitted and received from the communication unit 120. The processor 110 controls various operations of wireless signal transmission and reception of the station 100 according to an embodiment of the present invention. A detailed embodiment relating to this will be described later.

[0040] The station 100 shown in Figure 3 is a block diagram according to one embodiment of the present invention, and the separately shown blocks represent logically distinguished elements of the device. Therefore, the above-mentioned elements of the device are mounted on one chip or multiple chips depending on the device design. For example, the processor 110 and the communication unit 120 may be integrated and implemented on a single chip, or they may be implemented on separate chips. Furthermore, in the embodiment of the present invention, some components of the station 100, such as the user interface unit 140 and the display unit 150, may be selectively provided in the station 100.

[0041] Figure 4 is a block diagram showing the configuration of AP200 according to one embodiment of the present invention. As shown, AP200 according to an embodiment of the present invention includes a processor 210, a communication unit 220, and a memory 260. In Figure 4, redundant explanations are omitted for parts of the AP200 configuration that are the same as or correspond to the configuration of station 100 in Figure 3.

[0042] Referring to Figure 4, the AP200 according to the present invention includes a communication unit 220 for operating a BSS in at least one frequency band. As described in the embodiment of Figure 3, the communication unit 220 of the AP200 also includes multiple communication modules that utilize different frequency bands. In other words, the AP200 according to the embodiment of the present invention includes two or more communication modules from different frequency bands, for example, 2.4 GHz, 5 GHz, and 60 GHz. Preferably, the AP200 includes a communication module that utilizes a frequency band of 6 GHz or higher and a communication module that utilizes a frequency band of 6 GHz or lower. Each communication module communicates wirelessly with the station according to the wireless LAN standard of the frequency band supported by the communication module. Depending on the performance and requirements of the AP200, the communication unit 220 may operate only one communication module at a time or operate multiple communication modules together simultaneously. In the embodiment of the present invention, the communication unit 220 represents an RF communication module that processes RF signals.

[0043] Next, the memory 260 stores the control program used by the AP200 and various data associated with it. Such a control program includes a connection program that manages the connection of stations. The processor 210 controls each unit of the AP200 and controls the transmission and reception of data between units. According to an embodiment of the present invention, the processor 210 executes the program for connecting with stations stored in the memory 260 and transmits a communication setting message to one or more stations. In this case, the communication setting message includes information regarding the connection priority conditions of each station. The processor 210 also performs connection settings in response to connection requests from stations. According to one embodiment, the processor 210 is a modem or modulation / demodulation unit that modulates and demodulates the wireless signals transmitted and received from the communication unit 220. The processor 210 controls various operations of wireless signal transmission and reception of the AP200 according to an embodiment of the present invention. A detailed embodiment relating thereto will be described later.

[0044] Figure 5 is a schematic diagram illustrating the process by which STA establishes a link with AP.

[0045] Referring to Figure 5, the link between STA100 and AP200 is established through three main steps: scanning, authentication, and association. First, the scanning step is the step in which STA100 obtains connection information for the BSS operated by AP200. There are two methods for performing scanning: passive scanning, which obtains information using only the beacon message S101 that AP200 periodically transmits, and active scanning, in which STA100 transmits a probe request S103 to the AP, receives a probe response S105 from the AP, and obtains connection information.

[0046] In the scanning step, STA100, having successfully received wireless connection information, transmits an authentication request (S107a), receives an authentication response from AP200 (S107b), and performs the authentication step. After the authentication step is performed, STA100 transmits an association request (S109a), receives an association response from AP200 (S109b), and performs the association step. In this specification, "association" basically means wireless coupling, but the present invention is not limited to this, and in a broad sense, coupling includes both wireless and wired coupling.

[0047] On the other hand, an additional 802.1X-based authentication step S111 and an IP address acquisition step S113 via DHCP are performed. In Figure 5, Server 300 is a server that processes authentication between STA100 and the 802.1X-based system, and may be physically connected to AP200 or exist as a separate server.

[0048] Figure 6 shows the CSMA / CA method used in wireless LAN communication.

[0049] A terminal performing wireless LAN communication checks whether a channel is busy or not by performing carrier sensing before transmitting data. If a wireless signal above a certain strength is detected, the channel is determined to be busy, and the terminal delays access to that channel. This process is called Clear Channel Assessment (CCA), and the level at which the detection of the signal is determined is called the CCA threshold. If a wireless signal above the CCA threshold is received by the terminal and the terminal is the recipient, the terminal processes the received wireless signal. On the other hand, if no wireless signal is detected from the channel, or if a wireless signal below the CCA threshold is detected, the channel is determined to be idle.

[0050] If a channel is determined to be idle, each terminal with data to transmit performs a backoff procedure after a certain period of time, such as an IFS (Inter Frame Space) or PIFS (PCF IFS), depending on the status of each terminal. In this embodiment, the AIFS is used as a replacement for the conventional DIFS (DCF IFS). Each terminal waits, decreasing its slot time by a random number determined for that terminal during the interval of the channel's idle state, and the terminal that has exhausted all of its slot time attempts to access the channel. The period in which each terminal performs this backoff procedure is called the competition window period.

[0051] If a specific terminal successfully accesses the channel, it transmits data through the channel. However, if a terminal attempting access collides with another terminal, the colliding terminals are each assigned a new random number and perform a further backoff procedure. In one embodiment, the random number newly assigned to each terminal is determined within a range twice the range (competition window, CW) of the random number previously assigned to that terminal (2*CW). Meanwhile, each terminal attempts access again in the next competition window interval by performing a further backoff procedure, but this time, each terminal performs the backoff procedure from the slot time remaining in the previous competition window interval. In this way, each terminal performing wireless LAN communication can avoid collisions with each other for a specific channel.

[0052] Figure 7 shows a method for performing DCF using RTS frames and CTS frames.

[0053] APs and STAs within the BSS compete for the right to transmit data. Once the data transmission in the previous step is complete, each terminal with data to transmit performs a backoff procedure, decreasing a random number backoff counter (or backoff timer) assigned to each terminal after the AIFS time has elapsed. A transmitting terminal whose backoff counter has expired transmits an RTS frame to indicate that it has data to transmit. In the embodiment shown in Figure 7, STA1, which has the advantage in the competition with the minimum backoff, transmits an RTS frame after its backoff counter has expired. The RTS frame contains information such as the receiver address, transmitter address, and duration. The receiving terminal (i.e., the AP in Figure 7) that receives the RTS frame waits for the SIFS (Short IFS) time, and then transmits a CTS frame to indicate to the transmitting terminal STA1 that it is ready to transmit data. The CTS frame contains information such as the receiver address and duration. In this case, the receiver address of the CTS frame is set to be the same as the transmitter address of the corresponding RTS frame, that is, the address of the transmission terminal STA1.

[0054] Upon receiving a CTS frame, the transmission terminal STA1 transmits the data after the SIFS time. Once data transmission is complete, the receiving terminal AP transmits a response ACK frame after the SIFS time to indicate that data transmission is complete. If the response frame is received within a predetermined time, the transmission terminal considers the data transmission to have been successful. However, if the response frame is not received within the predetermined time, the transmission terminal considers the data transmission to have failed. Meanwhile, peripheral terminals that receive at least one of either an RTS frame or a CTS frame during the transmission process set a NAV (Network Allocation Vector) and refrain from transmitting data until the set NAV expires. In this case, each terminal's NAV is set based on the duration field of the received RTS frame or CTS frame.

[0055] In the data transmission process described above, if the terminal's RTS frame or CTS frame is not successfully transmitted to the target terminal (i.e., the terminal with the receiver address) due to interference, collision, or other circumstances, the execution of the next process is interrupted. Transmission terminal STA1, which transmitted the RTS frame, is deemed unable to transmit data and is assigned a new random number to participate in the next competition. In this case, the newly assigned random number is determined within a range twice the previously set random number range (competition window, CW) (2*CW), as described above.

[0056] Basic Sequence of UL-MU / DL-MU Transmission Figures 8 and 9 show a multi-user transmission method according to one embodiment of the present invention. By using OFDMA or Multi Input Multi Output (MIMO), one wireless communication terminal can transmit data to multiple wireless communication terminals simultaneously. Also, one wireless communication terminal can receive data from multiple wireless communication terminals simultaneously. For example, Downlink Multi-User (DL-MU) transmission is performed in which an AP transmits data to multiple STAs simultaneously, and Uplink Multi-User (UL-MU) transmission is performed in which multiple STAs transmit data to an AP simultaneously.

[0057] Figure 8 shows the UL-MU transmission process according to an embodiment of the present invention. For UL-MU transmission to occur, the channel used and the transmission start time of each STA performing uplink transmission must be coordinated. For efficient scheduling of UL-MU transmission, status information of each STA must be transmitted to the AP. According to an embodiment of the present invention, information for scheduling UL-MU transmission is indicated via a pre-configured field in the packet preamble and / or MAC header. For example, an STA indicates information for UL-MU transmission scheduling via a pre-configured field in the preamble or MAC header of the uplink transmission packet and transmits it to the AP. In this case, the information for UL-MU transmission scheduling includes at least one of the following: buffer status information of each STA and channel status information measured by each STA. The buffer status information of an STA indicates at least one of the following: whether or not the STA has uplink data to transmit, the access category (AC) of the uplink data, and the size (or transmission time) of the uplink data.

[0058] According to an embodiment of the present invention, the UL-MU transmission process is managed by the AP. UL-MU transmission is performed in response to a trigger frame transmitted by the AP. After receiving the trigger frame, the STA simultaneously transmits uplink data after a predetermined IFS time (e.g., SIFS). The trigger frame requests UL-MU transmission from the STA and informs the uplink transmission STA of the channel (or subchannel) information assigned to it. Upon receiving the trigger frame from the AP, multiple STAs transmit uplink data accordingly via their respective assigned channels (or subchannels). After the uplink data transmission is complete, the AP transmits an ACK to the STA that successfully transmitted the uplink data. At this time, the AP transmits a predetermined multi-STA block ACK (M-BA) as an ACK to multiple STAs.

[0059] In non-legacy wireless LAN systems, a specific number of subcarriers, such as 26, 52, or 106 tones, are used as Resource Units (RUs) for subchannel-level connections within a 20MHz band channel. Therefore, the trigger frame displays the identification information of each STA participating in the UL-MU transmission and the information of the assigned resource unit. The STA identification information includes at least one of the following: the STA's AID (Association ID), partial AID, or MAC address. The resource unit information includes the size and location information of the resource unit.

[0060] On the other hand, in non-legacy wireless LAN systems, UL-MU transmission is performed based on competition among multiple STAs for a specific resource unit. For example, if the AID field value for a particular resource unit is set to a specific value (e.g., 0) that is not assigned to an STA, multiple STAs will attempt random access (RA) to that resource unit.

[0061] Figure 9 shows a DL-MU transmission process according to an embodiment of the present invention. According to one embodiment of the present invention, RTS and / or CTS frames in a pre-configured format are used for setting the NAV in the DL-MU transmission process. First, the AP transmits a multi-user RTS (MU-RTS) frame for setting the NAV in the DL-MU transmission process. The duration field of the MU-RTS frame is set to the time when the DL-MU transmission session ends. In other words, the duration field of the MU-RTS frame is set based on the period until the AP's downlink data transmission and the STA's ACK frame transmission are completed. Peripheral terminals of the AP set the NAV until the end of the DL-MU transmission session based on the duration field of the MU-RTS frame transmitted by the AP. According to one embodiment, the MU-RTS frame consists of a trigger frame format and requests the transmission of a simultaneous CTS (sCTS) frame from the STA.

[0062] STAs (STA1, STA2) that receive MU-RTS frames from APs transmit sCTS frames. sCTS frames transmitted by multiple STAs have the same waveform. That is, the sCTS frame transmitted by STA1 via the first channel has the same waveform as the sCTS frame transmitted by STA2 via the first channel. In one embodiment, the sCTS frame is transmitted to the channel indicated by the MU-RTS frame. The duration field of the sCTS frame is set to the time when the DL-MU transmission session ends, based on the information in the duration field of the MU-RTS frame. In other words, the duration field of the sCTS frame is set based on the period until the AP's downlink data transmission and the STA's ACK frame transmission are completed. In Figure 9, the peripheral terminals of STA1 and STA2 set NAVs based on the duration field of the sCTS frame until the end of the DL-MU transmission session.

[0063] According to one embodiment of the present invention, MU-RTS frames and sCTS frames are transmitted in 20MHz channel units. Therefore, peripheral terminals, including legacy terminals, receive MU-RTS frames and / or sCTS frames and set up the NAV. Once the transmission of MU-RTS frames and sCTS frames is complete, the AP performs downlink transmission. Figure 9 shows an embodiment in which the AP transmits DL-MU data to STA1 and STA2, respectively. The STA receives the downlink data transmitted by the AP and transmits an uplink ACK accordingly.

[0064] PPDU format Figure 10 shows an example of a legacy PPDU (PHY Protocol Data Unit) format and a non-legacy PPDU format. More specifically, Figure 10(a) shows an example of a legacy PPDU format based on 802.11a / g, and Figure 10(b) shows an example of a non-legacy PPDU (i.e., HE PPDU) format based on 802.11ax. Figure 10(c) shows the configuration of the detailed fields of L-SIG and RL-SIG commonly used in the aforementioned PPDU formats.

[0065] Referring to Figure 10(a), the preamble for a legacy PPDU includes L-STF (Legacy Short Training field), L-LTF (Legacy Long Training field), and L-SIG (Legacy Signal field). In embodiments of the present invention, L-STF, L-LTF, and L-SIG are referred to as the legacy preamble. Referring to Figure 10(b), the preamble for an HE PPDU further includes RL-SIG (Repeated Legacy Short Training field), HE-SIG-A (High Efficiency Signal A field), HE-SIG-B (High Efficiency Signal B field), HE-STF (High Efficiency Short Training field), and HE-LTF (High Efficiency Long Training field) in addition to the legacy preamble. In embodiments of the present invention, RL-SIG, HE-SIG-A, HE-SIG-B, HE-STF, and HE-LTF are referred to as the non-legacy preamble. The specific structure of the non-gassy preamble varies depending on the HE PPDU format. For example, HE-SIG-B is used in only some HE PPDU formats.

[0066] The L-SIG included in the PPDU preamble is encoded using 64FFT OFDM and consists of a total of 64 subcarriers. Of these, 48 subcarriers, excluding the guard subcarrier, DC subcarrier, and pilot subcarrier, are used for L-SIG data transmission. If BPSK, Rate=1 / 2 MCS (Modulation and Coding Scheme) is applied, the L-SIG will contain a total of 24 bits of information. Figure 10(c) shows the structure of the 24 bits of information in the L-SIG.

[0067] Referring to Figure 10(c), the L-SIG includes the L_RATE field and the L_LENGTH field. The L_RATE field consists of 4 bits and indicates the MCS used for data transmission. Specifically, the L_RATE field indicates at least one value from the transmission speeds of 6 / 9 / 12 / 18 / 24 / 36 / 48 / 54 Mbps, which are a combination of a modulation scheme such as BPSK / QPSK / 16-QAM / 64-QAM and a code rate such as 1 / 2, 2 / 3, or 3 / 4. Combining the information from the L_RATE and L_LENGTH fields allows us to determine the total length of the PPDU in question. Non-legacy PPDUs set the L_RATE field to the minimum speed of 6 Mbps.

[0068] The L_LENGTH field consists of 12 bits and, in combination with the L_RATE field, can indicate the length of the corresponding PPDU. In this case, legacy terminals and non-legacy terminals parse the L_LENGTH field in different ways.

[0069] First, the method by which legacy or non-legacy terminals analyze the length of a PPDU using the L_LENGTH field is as follows: If the L_RATE field is set to 6Mbps, then 3 bytes (i.e., 24 bits) are transmitted for 4us, which is the symbol duration of one 64FFT. Therefore, by adding the 3 bytes corresponding to the SVC field and Tail field to the L_LENGTH field value and dividing by the 3 bytes that represent the transmission amount of one symbol, the number of symbols based on 64FFT from L_SIG onward is obtained. After multiplying the obtained number of symbols by the symbol duration of one, 4us, and then adding the 20us required for the transmission of L-STF, L-LTF, and L-SIG, the length of the PPDU, i.e., the reception time (RXTIME), is obtained. This can be expressed mathematically as shown in Equation 1 below.

[0070]

number

[0071] At this time,

[0072]

number

[0073] represents the smallest natural number greater than or equal to x. Since the maximum value of the L_LENGTH field is 4095, the length of the PPDU can be set to a maximum of 5.464 ms. Non-legacy terminals transmitting the PPDU should set the L_LENGTH field as shown in Equation 2 below.

[0074]

number

[0075] Here, TXTIME is the total transmission time that constitutes the PPDU, and is given by the following equation 3. In this case, T xThis indicates the transmission time of X.

[0076]

number

[0077] Referring to the above formula, the length of the PPDU is calculated based on the value of L_LENGTH / 3 rounded up. Therefore, for any k value, three different values ​​L_LENGTH={3k+1, 3k+2, 3(k+1)} indicate the same PPDU length. According to an embodiment of the present invention, a non-legacy terminal performs additional signaling using three different L_LENGTH values ​​that indicate the same PPDU length information. More specifically, the values ​​corresponding to 3k+1 and 3k+2 among the three distinct L_LENGTH values ​​are used to indicate the HE PPDU format.

[0078] Figure 11 shows various HE PPDU formats and methods for indicating them according to embodiments of the present invention. According to embodiments of the present invention, the HE PPDU format is indicated based on the L_LENGTH field and HE-SIG-A of the PPDU in question. More specifically, the HE PPDU format is indicated based on the value of the L_LENGTH field and at least one of the modulation techniques applied to the HE-SIG-A symbol.

[0079] First, referring to Figure 11(a), if the value of the L_LENGTH field is in the form of 3k+1 (i.e., mod3=1), then the PPDU is either an HE SU PPDU or an HE Trigger-based PPDU. An HE SU PPDU is a PPDU used for single-user transmission between an AP and a single STA, while an HE Trigger-based PPDU is an uplink PPDU used for transmissions that are responses to a trigger frame. HE SU PPDUs and HE Trigger-based PPDUs have the same pre-angle format. In the case of HE SU PPDUs and HE Trigger-based PPDUs, the two symbols HE-SIG-A are modulated to BPSK and BPSK, respectively.

[0080] According to an additional embodiment of the present invention shown in Figure 11(b), a PPDU is an extended PPDU if the value of the L_LENGTH field is in the form of 3k+1 (i.e., mod3=1) and the two symbols HE-SIG-A are modulated to BPSK and QBPSK, respectively. Extended PPDUs are used as new PPDU formats other than the PPDU formats supported by 802.11ax.

[0081] Next, if the value of the L_LENGTH field is in the form of 3k+2 (i.e., mod=2), then the PPDU is either an HE MU PPDU or an HE Extended Range (ER) SU PPDU. An HE MU PPDU is a PPDU used for transmission to one or more terminals. The HE MU PPDU format is shown in Figure 11(c), and it includes HE-SIG-B in addition to the non-legacy preamble. In the case of an HE MU PPDU, the two symbols of HE-SIG-A are modulated to BPSK and BPSK, respectively. On the other hand, an HE ER SU PPDU is used for single-user transmission to terminals in the extended range. The HE ER SU PPDU format is shown in Figure 11(d), and it repeats HE-SIG-A in the non-legacy preamble over time. In the case of an HE ER SU PPDU, the first two symbols of HE-SIG-A are modulated to BPSK and QBPSK, respectively. Thus, non-legacy terminals signal the PPDU format via the modulation technique used for the two HE-SIG-A symbols in addition to the value of the L_LENGTH field.

[0082] The HE MU PPDU shown in Figure 11(c) is used by an AP to perform downlink transmission to multiple STAs. In this case, the HE MU PPDU includes scheduling information for multiple STAs to receive the PPDU simultaneously. In addition, the HE MU PPDU may be used by a single STA to perform uplink transmission to the AP. In this case, the HE MU PPDU transmits the AID information of the recipient and / or sender of the PPDU via the user-specific field of HE-SIG-B. Therefore, a terminal that receives the HE MU PPDU performs spatial reuse based on the AID information obtained from the preamble of the PPDU. Furthermore, data transmission is performed over a narrowband using the HE MU PPDU. Here, the narrowband is a frequency band of less than 20 MHz. According to one embodiment, the HE MU PPDU instructs the allocation information of resource units used for narrowband transmission via HE-SIG-B.

[0083] More specifically, the resource unit allocation (RA) field in HE-SIG-B contains information about the resource unit partitioning configuration within a specific bandwidth (e.g., 20 MHz) from the frequency domain. Furthermore, the STA information assigned to each partitioned resource unit is transmitted via the user-specific field in HE-SIG-B. The user-specific field includes one or more user fields corresponding to each partitioned resource unit.

[0084] If narrowband transmission is performed using a portion of the divided resource units, the resource unit on which transmission is performed is indicated via the user identification field of HE-SIG-B. In one embodiment, the AID of the receiver or sender is inserted into the user field corresponding to the resource unit(s) on which data transmission is performed among the multiple divided resource units, and a pre-set null STA ID is inserted into the user field corresponding to the remaining resource unit(s) on which data transmission is not performed. In another embodiment of the present invention, narrowband transmission is signaled via a first user field corresponding to the resource unit on which data transmission is not performed and a second user field corresponding to the resource unit on which data transmission is performed. More specifically, a pre-set null STA ID is inserted into the first user field, and the location information of the resource unit(s) on which data transmission is performed is indicated via the remaining subfields of the user field. Next, the AID of the receiver or sender is inserted into the second user field. In this way, the terminal signals narrowband transmission via the location information contained in the first user field and the AID information contained in the second user field. In this case, only a number of user fields less than the number of divided resource units are used, thus reducing signaling overhead.

[0085] Configuration of HE-SIG-A and HE-SIG-B fields in HE PPDU Figure 12 shows an example of the configuration of the HE-SIG-A field in the HE PPDU format. HE-SIG-A consists of two 64FFT symbols that indicate common information for receiving HE PPDU. The first symbol of HE-SIG-A is modulated to BPSK, and the second symbol is modulated to either BPSK or QBPSK. In HE ER SU PPDU, the two symbols of HE-SIG-A are transmitted repeatedly. That is, HE-SIG-A in HE ER SU PPDU consists of four symbols, of which the first and second symbols have the same data bits, and the third and fourth symbols have the same data bits.

[0086] First, Figure 12(a) shows the subfield configuration of the HE-SIG-A field of HE SU PPDU. According to one embodiment, the HE-SIG-A field of HE ER SU PPDU is configured in the same way. The function of each field included in HE-SIG-A is explained below.

[0087] The Upstream / Downstream field indicates the transmission direction of the PPDU. In other words, this field indicates whether the PPDU is being transmitted upstream or downstream. The Format field is used to distinguish between HE SU PPDUs and HE Trigger-based PPDUs. The BSS Color field consists of 6 bits and indicates the BSS identifier corresponding to the terminal that transmitted the PPDU. The Spatial Reuse field transmits information such as SINR (Signal to Interference plus Noise Ratio) and transmission power that can be referenced by terminals attempting to perform spatial reuse transmission while the PPDU is being transmitted.

[0088] The TXOP duration field indicates duration information for TXOP protection and NAV setting. This field sets the duration of the TXOP interval during which continuous transmission occurs after the PPDU, allowing peripheral terminals to set NAV during that period. The bandwidth field indicates the total bandwidth width over which the PPDU is transmitted. In one embodiment, the bandwidth field consists of 2 bits and indicates one of 20MHz, 40MHz, 80MHz, and 160MHz (including 80+80MHz). The MCS field indicates the MCS value applied to the data field of the PPDU. The CP+LTF size field indicates the duration of the CP (Cyclic Prefix) or GI (Guard Interval) and the size of the HE-LTF. More specifically, this field indicates a combination of the HE-LTF size used from 1x, 2x, 4x, or HE-LTF, and the CP (or GI) value used in the data field from 0.8us, 1.6us, or 3.2us.

[0089] The coding field indicates whether BCC (Binary Convolutional Code) or LDPC (Low Density Parity Check) coding techniques are used. This field also indicates the presence of additional OFDM symbols for LDPC. The NSTS (Number of Space Time Streams) field indicates the number of space-time streams used in MIMO transmission. The STBC (Space Time Block Coding) field indicates whether space-time block coding was used. The TxBF (Transmit Beamforming) field indicates whether beamforming was applied to the transmission of the PPDU. The DCM (Dual Carrier Modulation) field indicates whether dual-carrier modulation was applied to the data field. Dual-carrier modulation transmits the same information to two subcarriers to mitigate narrowband interference. The packet expansion field indicates the level of packet expansion applied to the PPDU. The beam exchange field indicates whether the portion of the PPDU prior to the HE-STF is mapped spatially differently from the HE-LTF. The CRC field and tail field are used to determine the truth value of the HE-SIG-A field information and to initialize the BCC decoder, respectively.

[0090] Next, Figure 12(b) shows the subfield configuration of the HE-SIG-A field of the HE MU PPDU. For the subfields in Figure 12(b) that are the same as those described in Figure 12(a), redundant explanations are omitted.

[0091] The uplink / downlink field indicates the transmission direction of the PPDU. In other words, this field indicates whether the PPDU is an uplink or downlink transmission. The bandwidth field of the HE MU PPDU indicates an additional bandwidth in addition to the bandwidth of the HE SU PPDU. That is, the bandwidth field of the HE MU PPDU consists of 3 bits and indicates one of the following: 20MHz, 40MHz, 80MHz, 160MHz (including 80+80MHz), and a pre-set discontinuous bandwidth. Specific examples of the pre-set discontinuous bandwidth will be described later.

[0092] The SIG-B MCS field indicates the MCS applied to the HE-SIG-B field. HE-SIG-B has a variable MCS applied between MCS0 and MCS5, depending on the amount of information that needs to be signaled. The CP+LTF size field indicates the duration of CP or GI and the size of HE-LTF. This field shows the HE-LTF size used from 2x, 4x, or HE-LTF, and the combination of CP (or GI) values ​​used in the data field from 0.8us, 1.6us, or 3.2us.

[0093] The SIG-B compression field indicates whether the compression mode of the HE-SIG-B field is available. If HE MU PPDU is transmitted using MU-MIMO across the full bandwidth, resource unit allocation information for each 20MHz band becomes unnecessary. Therefore, in full-bandwidth MU-MIMO transmission, the SIG-B compression field indicates the compression mode of the HE-SIG-B field, but in this case, the common field including the resource unit allocation field does not exist in the HE-SIG-B field. The SIG-B DCM field indicates whether the field has been modulated with DCM for stable transmission of the HE-SIG-B field. The HE-SIG-B symbol count field indicates the number of OFDM symbols in the HE-SIG-B field.

[0094] On the other hand, as will be described later, when the HE MU PPDU is transmitted in a bandwidth of 40 MHz or higher, HE-SIG-B consists of two types of content channels in 20 MHz units. These are referred to as HE-SIG-B content channel 1 and HE-SIG-B content channel 2, respectively. According to one embodiment of the present invention, if the MCS applied to HE-SIG-B content channel 1 and HE-SIG-B content channel 2 are different, the number of HE-SIG-B symbols in each channel is maintained to be the same. The HE-SIG-A field of the HE MU PPDU includes a SIG-B dual MCS field, which indicates whether the MCS applied to HE-SIG-B content channel 1 and HE-SIG-B content channel 2 are different from each other.

[0095] According to an embodiment of the present invention, if the SIG-B compression field indicates the compression mode of the HE-SIG-B field (i.e., indicates full-bandwidth MU-MIMO transmission), then a specific subfield of HE-SIG-A indicates the number of MU-MIMO users. For example, if full-bandwidth MU-MIMO transmission is performed, HE-SIG-B content channel 1 and HE-SIG-B content channel 2 do not need to distribute the amount of information through different MCSs. Therefore, if the SIG-B compression field indicates the compression mode of the HE-SIG-B field, the SIG-B dual MCS field of HE-SIG-A indicates the number of MU-MIMO users. Similarly, if full-bandwidth MU-MIMO transmission is performed, there is no need to individually transmit the number of symbols for each HE-SIG-B content channel. Therefore, if the SIG-B compression field indicates the compression mode of the HE-SIG-B field, the HE-SIG-B symbol count field of HE-SIG-A indicates the number of MU-MIMO users. Thus, in a compression mode where the HE-SIG-B resource unit allocation field is omitted, the number of MU-MIMO users is indicated via a specific subfield of HE-SIG-A.

[0096] According to an additional embodiment of the present invention, some subfields of the HE-SIG-A field of the HE MU PPDU signal different information through a combination of multiple subfields than in the embodiments described above. As described above, the HE MU PPDU may be used not only for an AP to perform downlink transmission to multiple STAs, but also for a single STA to perform uplink transmission to the AP. According to one embodiment of the present invention, specific subfields of the HE-SIG-A field of the HE MU PPDU signal or are set to signal different information based on the values ​​indicated by the uplink / downlink fields.

[0097] First, the bandwidth field indicates different information based on the value indicated by the uplink / downlink field. If the uplink / downlink field indicates downlink transmission, the bandwidth field indicates one of the following: 20MHz, 40MHz, 80MHz, 160MHz (including 80+80MHz), and a pre-configured discontinuous bandwidth. In a 3-bit bandwidth field, values ​​0-3 indicate 20MHz, 40MHz, 80MHz, and 160MHz (including 80+80MHz), respectively, and one of the values ​​4-7 indicates one of the pre-configured discontinuous bandwidths. However, discontinuous bandwidth PPDUs are only available for downlink transmission. Therefore, specific values ​​in the bandwidth field (i.e., one or more values ​​from 4-7) indicate different information depending on whether the uplink / downlink field indicates downlink transmission or uplink transmission.

[0098] For example, if the uplink / downlink field indicates uplink transmission, the bandwidth field may indicate one of 20MHz, 40MHz, 80MHz, 160MHz (including 80+80MHz), and a preset narrow bandwidth. In other words, in a 3-bit bandwidth field, values ​​0 to 3 indicate 20MHz, 40MHz, 80MHz, and 160MHz (including 80+80MHz), respectively, and one of values ​​4 to 7 indicates one of the preset narrow bandwidths. In one embodiment, the preset narrow bandwidth includes a left-106 tone and a right-106 tone. In this case, of the 242 tones that make up the 20MHz main channel, the left-106 tone refers to a low-frequency 106-tone resource unit, and the right-106 tone refers to a high-frequency 106-tone resource unit. However, the present invention is not limited to this, and the pre-set narrow bandwidth may include one or more of the following: 26-tone resource units, 52-tone resource units, 106-tone resource units, or a combination thereof.

[0099] Thus, when transmitting UL MU PPDU, data transmission is performed via a pre-set narrowband within the 20MHz bandwidth. The resource unit allocation information used for narrowband transmission may be indicated via the resource unit allocation field and user identification field of HE-SIG-B, but in this case, there is a risk of significant signaling overhead. Therefore, according to one embodiment of the present invention, uplink narrowband transmission is indicated via the bandwidth field of HE-SIG-A of the HE MU PPDU.

[0100] Next, the SIG-B compression field is set differently based on the values ​​indicated by the uplink / downlink fields. The SIG-B compression field indicates whether the compression mode of the HE-SIG-B field is available. If the SIG-B compression field indicates the compression mode of the HE-SIG-B field, then the common fields, including the resource unit allocation field, are not present in the HE-SIG-B field. According to embodiments of the present invention, the SIG-B compression field is set according to different rules depending on whether the uplink / downlink fields indicate downlink transmission or uplink transmission.

[0101] More specifically, if the uplink / downlink fields indicate downlink transmission, the SIG-B compression field indicates whether full-bandwidth MU-MIMO transmission is possible. In other words, if full-bandwidth MU-MIMO transmission is performed, the value of the SIG-B compression field is set to 1. Otherwise, the value of the SIG-B compression field is set to 0. However, in single-STA UL MU PPDU transmission, signaling of the resource allocation unit field is unnecessary. Therefore, if the uplink / downlink fields indicate uplink transmission, the SIG-B compression field is always set to 1. In other words, if the uplink / downlink fields indicate uplink transmission, the SIG-B compression field always indicates that there is no common field in the HE-SIG-B field. Even if full-bandwidth MU-MIMO transmission is not performed, the HE-SIG-B field compression mode is used to reduce the signaling overhead of HE-SIG-B for uplink transmission. Therefore, the common field is omitted in the HE-SIG-B field of UL MU PPDU.

[0102] Next, the count field of the HE-SIG-B symbol indicates different information based at least partially on the values ​​indicated by the up / down fields. More specifically, the count field of the HE-SIG-B symbol indicates different information based on the values ​​indicated by the up / down fields and the values ​​in the SIG-B compression field.

[0103] The HE-SIG-B symbol count field basically indicates the number of OFDM symbols in the HE-SIG-B field. However, as in the embodiment described above, if the uplink / downlink field indicates downlink transmission and the SIG-B compression field indicates the compression mode of the HE-SIG-B field, then the HE-SIG-B symbol count field of HE-SIG-A indicates the number of MU-MIMO users. In this case, the user identification field of the HE-SIG-B field consists of the user field for MU-MIMO allocation. On the other hand, if the value of the SIG-B compression field of UL MU PPDU is set to 1, it may be intended to omit the resource unit allocation field rather than indicating full bandwidth MU-MIMO transmission. Therefore, if the uplink / downlink fields indicate uplink transmission and the SIG-B compression field indicates the compression mode of the HE-SIG-B field, the HE-SIG-A HE-SIG-B symbol count field indicates the number of OFDM symbols in the HE-SIG-B field, as per the basic definition. In this case, the user-specific field of the HE-SIG-B field consists of a user field for non-MU-MIMO assignment. According to one embodiment, since the UL MU PPDU is transmitted to a single AP, the user-specific field of the HE-SIG-B field contains only one user field for non-MU-MIMO assignment.

[0104] Next, Figure 12(c) shows the subfield configuration of the HE-SIG-A field in the HE Trigger-based PPDU. For subfields in Figure 12(c) that are the same as those described in Figure 12(a) or Figure 12(b), redundant explanations are omitted.

[0105] The format field is used to distinguish between HE SU PPDU and HE Trigger-based PPDU. HE Trigger-based PPDU also includes the BSS color field and TXOP duration field mentioned above. The spatial reuse field of HE Trigger-based PPDU consists of 16 bits and transmits information for spatial reuse operation in units of 20 MHz or 40 MHz depending on the total bandwidth. The bandwidth field consists of 2 bits and indicates one of the following: 20 MHz, 40 MHz, 80 MHz, and 160 MHz (including 80+80 MHz).

[0106] Figure 13 shows the configuration of the HE-SIG-B field according to one embodiment of the present invention. The HE-SIG-B field is present in the HE MU PPDU and is transmitted in 20 MHz units. The HE-SIG-B field also indicates the information necessary to receive the HE MU PPDU. As shown in Figure 13(a), the HE-SIG-B consists of a common field and a user-specific field.

[0107] Figure 13(b) shows one example of the subfield configuration of the common field in HE-SIG-B. First, the common field includes the resource unit allocation RA field. Figure 13(c) shows one example of the RA field.

[0108] Referring to Figure 13(c), the RA field contains information regarding resource unit allocation for a specific bandwidth (e.g., 20 MHz) in the frequency domain. More specifically, the RA field consists of 8-bit units and indexes the size of the resource units constituting the specific bandwidth and their arrangement in the frequency domain. The RA field also indicates the number of users in each resource unit. If the total bandwidth through which the PPDU is transmitted is greater than a preset bandwidth (e.g., 40 MHz), the RA field is set to a size that is a multiple of 8 bits to transmit information in the aforementioned specific bandwidth units.

[0109] Each divided resource unit is generally assigned to one user. However, resource units with a bandwidth exceeding a certain level (e.g., 106-tones) are assigned to multiple users using MU-MIMO. In this case, the RA field indicates the number of users for the relevant resource unit. Furthermore, the RA field, via a pre-configured index, indicates specific resource units that are not transmitted by the user-specific field, i.e., specific resource units that are not assigned to a user (i.e., empty RUs). According to one embodiment, specific resource units include resource unit RUs with bandwidths that are multiples of a 20MHz channel, i.e., 242-tone RUs, 484-tone RUs, 996-tone RUs, etc. Data is not transmitted in the empty RUs indicated by the index value. In this way, the terminal signals discontinuous channel assignment information in 20MHz units via the pre-configured index of the RA field of HE-SIG-B.

[0110] According to one embodiment of the present invention, if the PPDU is transmitted with a response bandwidth of 80 MHz or more, the common field further includes a field (hereinafter referred to as the C26 field) indicating whether or not the central 26-tone RU at 80 MHz has been assigned to the user. The C26 field consists of a 1-bit indicator located before or after the RA field in the common field.

[0111] On the other hand, the user-specific field consists of multiple user fields and transmits information for the STA specified to each assigned resource unit. The total number of user fields included in the user-specific field is determined based on the RA field and the C26 field. Multiple user fields are transmitted in units of user block fields. A user block field is made up of a combination of two user fields, a CRC field, and a tail field. Depending on the total number of user fields, the last user block field contains information for one or two STAs. For example, if a total of three users (i.e., STA1, STA, and STA3) are specified, the first user block field will encode information for STA1 and STA2 and transmit both the CRC and tail fields, while the last user block field will encode information for STA3 and transmit both the CRC and tail fields.

[0112] Figures 13(d)-1 and 13(d)-2 show examples of the configuration of the subfields of the HE-SIG-B user field, respectively. Figure 13(d)-1 shows the user field for OFDMA transmission, and Figure 13(d)-2 shows the user field for MU-MIMO transmission. Each user field indicates the receiver AID of the corresponding resource unit. Exceptionally, if the HE MU PPDU is used for uplink transmission, the user field indicates the sender AID. If one user is assigned to one resource unit (i.e., non-MU-MIMO assignment), the user field is NSTS, T, as shown in Figure 13(d)-1. xThe user field includes the BF, MCS, DCM, and coding fields. On the other hand, if multiple users are assigned to a single resource unit (i.e., MU-MIMO assignment), the user field includes the spatial configuration field (SCF), MCS, DCM, and coding fields, as shown in Figure 13(d)-2. Each STA receiving a PPDU via MU-MIMO assignment should identify the location and number of spatial streams for itself in the relevant resource unit. For this purpose, the user field for MU-MIMO transmission includes the spatial configuration field (SCF).

[0113] Figure 13(e) shows an example of the SCF for HE-SIG-B. The SCF indicates the number of spatial streams for each STA and the total number of spatial streams in the MU-MIMO allocation. Each STA identifies the OFDMA and / or MIMO allocation of the corresponding PPDU via the RA field and identifies whether the STA receives data via the MU-MIMO allocation, depending on the order in which they are called on the user-specific field. If the STA receives data via a non-MU-MIMO allocation, the user field is parsed in the format of Figure 13(d)-1. However, if the STA receives data via the MU-MIMO allocation, the user field is parsed in the format of Figure 13(d)-2. On the other hand, if the SIG-B compression field indicates overall bandwidth MU-MIMO, there is no RA field in HE-SIG-B. In this case, all STAs signaled on the user-specific field receive data via the MU-MIMO allocation, and therefore the STAs parsed the user field in the format of Figure 13(d)-2.

[0114] As in the embodiment described above, if the SIG-B compression field indicates overall bandwidth MU-MIMO, then the specific subfield of HE-SIG-A indicates the number of MU-MIMO users. In other words, if the SIG-B compression field indicates the compression mode of the HE-SIG-B field, then the HE-SIG-B symbol count field of HE-SIG-A indicates the number of MU-MIMO users. In an additional embodiment of the present invention, if the SIG-B compression field indicates overall bandwidth MU-MIMO, the configuration of the user-specific field of HE-SIG-B is identified based on the number of MU-MIMO users indicated by the HE-SIG-B symbol count field. For example, the type of user field constituting the user-specific field is determined from user fields for MU-MIMO assignment and user fields for non-MU-MIMO assignment based on the number of MU-MIMO users.

[0115] More specifically, if the SIG-B compression field indicates overall bandwidth MU-MIMO and the HE-SIG-B symbol count field indicates two or more users, then the HE-SIG-B user identification field consists of a user field for MU-MIMO assignment. In one embodiment, if the HE-SIG-B symbol count field indicates two or more users, it is set to a value of 1 or more. In this case, the receiving terminal of the PPDU receives the data via MU-MIMO assignment.

[0116] However, if the SIG-B compression field indicates overall bandwidth MU-MIMO and the HE-SIG-B symbol count field indicates a single user, then the HE-SIG-B user identification field consists of a single user field for non-MU-MIMO assignment. According to one embodiment, if the HE-SIG-B symbol count field indicates a single user, it is set to 0. In this case, the receiving terminal of the PPDU receives the data via non-MU-MIMO assignment. This is because if the SIG-B compression field indicates overall bandwidth MU-MIMO but only one receiver is indicated, the transmission will not be analyzed as MU-MIMO transmission. Also, if only one user is assigned to MU-MIMO transmission, the SCF of the user field for MU-MIMO assignment shown in Figures 13(d) and 13(e) cannot signal spatial stream information for a single user. Therefore, if overall bandwidth MU-MIMO is indicated along with a single user, the HE-SIG-B user identification field consists of a user field for non-MU-MIMO assignment. This configuration of the HE-SIG-B user identification field, based on the number of MU-MIMO users, applies to all uplink and downlink MU PPDUs.

[0117] According to an additional embodiment of the present invention, in UL MU PPDU, there is always no common field in the HE-SIG-B field. During single-STA UL MU PPDU transmission, signaling of the C26 and RA fields within the common field may be unnecessary. Therefore, if the uplink / downlink fields indicate uplink transmission, there is no common field in the HE-SIG-B field. According to one embodiment, in UL MU PPDU, the value of the SIG-B compression field of HE-SIG-A is set to 1, explicitly signaling that HE-SIG-B does not contain a common field. However, in this case, overall bandwidth MU-MIMO transmission is not performed, but the compression mode of the HE-SIG-B field is used to reduce the signaling overhead of HE-SIG-B for uplink transmission. According to another embodiment of the present invention, in UL MU PPDU, the compression mode of the HE-SIG-B field is implicitly indicated regardless of the value of the SIG-B compression field, and there is no common field in the HE-SIG-B field.

[0118] Furthermore, according to one embodiment of the present invention, in UL MU PPDU, the HE-SIG-B user identification field consists of a single user field for non-MU-MIMO assignment. In other words, even when the value of the SIG-B compression field in UL MU PPDU is set to 1 to indicate the compression mode (or overall bandwidth MU-MIMO) of the HE-SIG-B field, the HE-SIG-B user identification field consists of a user field for non-MU-MIMO assignment. Thus, when a single STA transmits uplink to a single AP, a non-MU-MIMO-based (or OFDMA-based) user field, rather than a MU-MIMO-based user field, is transmitted, ensuring that the number of spatiotemporal streams to be received by the receiving terminal is accurately transmitted.

[0119] A terminal according to an embodiment of the present invention generates an HE MU PPDU containing the HE-SIG-A field and HE-SIG-B field configured by the method described above, and transmits the generated HE MU PPDU. A terminal that receives an HE MU PPDU decodes the PPDU based on information obtained from the HE-SIG-A field of the received PPDU. The terminal also decodes the HE-SIG-B field based on information obtained from the HE-SIG-A field of the received HE MU PPDU. As in the embodiment described above, the configuration of HE-SIG-B is identified based on information obtained from at least one field of HE-SIG-A. For example, the configuration of HE-SIG-B is identified based on at least one of the HE-SIG-B symbol count field, the SIG-B compression field, and combinations thereof. Figures 14 and 15 show specific examples of transmitting UL MU PPDU to a single STA and AP.

[0120] First, Figure 14 shows an example of STA performing UL MU PPDU transmission over a narrowband. Here, the narrowband is a resource unit with a bandwidth of less than 20 MHz. As shown in Figure 14(a), STA increases the data transmission distance by concentrating transmission power on a specific resource unit in the narrowband. Figures 14(b) to 14(d) show various examples of signaling such narrowband transmission.

[0121] First, narrowband transmission is signaled via at least one subfield of HE-SIG-A, as shown in Figure 14(b). If HE MU PPDU is used for uplink transmission, the bandwidth field of HE-SIG-A indicates one of 20MHz, 40MHz, 80MHz, 160MHz (including 80+80MHz), and a preset narrowband. In other words, in a 3-bit bandwidth field, values ​​0 to 3 indicate 20MHz, 40MHz, 80MHz, and 160MHz (including 80+80MHz), respectively, and one of values ​​4 to 7 indicates one of the preset narrowbands. In one embodiment, the preset narrowband includes a left-106-tone and a right-106-tone. In this case, of the 242-tones that make up the 20MHz main channel, the left-106-tone refers to a lower frequency 106-tone resource unit, and the right-106-tone refers to a higher frequency 106-tone resource unit. However, the present invention is not limited to this, and the pre-set narrow bandwidth may include one or more of the following: 26-tone resource units, 52-tone resource units, 106-tone resource units, or a combination thereof.

[0122] Next, narrowband transmission is signaled via a null STA ID inserted into the HE-SIG-B user field, as shown in Figure 14(c). More specifically, the RA field of HE-SIG-A indicates information about the resource unit division configuration on a particular channel. For example, if a 20MHz bandwidth is divided into two 106-tone resource units based on OFDMA, and the central 26-tone resource unit is not used, the RA field signals "0110zzzz" as shown in Figure 14(c). In this case, the receiver or sender's AID is inserted into the user field corresponding to the resource unit used for uplink data transmission among the two divided 106-tone resource units. Conversely, a null STA ID is inserted into the user field corresponding to the remaining resource unit for which no data transmission takes place. For example, if data is transmitted only through the second RU of the two 106-tone resource units, a null STA ID is inserted into the first user field.

[0123] According to another embodiment of the present invention, as shown in Figure 14(d), an index value for uplink resource unit allocation is newly defined in the RA field of HE-SIG-B for narrowband transmission. More specifically, the RA field of HE-SIG-B indexes a specific 106-tone RU on which uplink transmission is performed. In this case, since only one user field corresponding to the resource unit indicated by the RA field is carried, the signaling overhead is greatly reduced. According to one embodiment, the index value for uplink resource unit allocation is used from the unallocated (i.e., TBD) indices of the RA field configuration for DL-MU transmission. According to another embodiment, an index value for uplink resource unit allocation is newly defined within the RA field.

[0124] Figure 15 shows an example in which STA performs UL MU PPDU transmission over a bandwidth of 20 MHz or more. As shown in Figure 15(a), uplink transmission using HE MU PPDU is performed not only over narrowband but also over the full bandwidth of 20 MHz, 40 MHz, 80 MHz, and 160 MHz (including 80+80 MHz). In this case, the bandwidth field of HE-SIG-A indicates the total bandwidth of the PPDU. Also, as shown in Figure 15(b), the SIG-B compression field is always set to 1, and the common field is omitted from the HE-SIG-B field.

[0125] As in the embodiment described above, if the uplink / downlink fields indicate downlink transmission and the SIG-B compression field indicates the compression mode of the HE-SIG-B field, then the HE-SIG-B symbol count field of HE-SIG-A indicates the number of MU-MIMO users. In this case, the user identification field of the HE-SIG-B field consists of the user field for MU-MIMO assignment. However, as in the embodiment shown in Figure 15, if the uplink / downlink fields indicate uplink transmission and the SIG-B compression field indicates the compression mode of the HE-SIG-B field, then the HE-SIG-B symbol count field of HE-SIG-A indicates the number of OFDM symbols in the HE-SIG-B field, as in the basic definition. In this case, the identification field of the HE-SIG-B field consists of the user field for non-MU-MIMO assignment.

[0126] Figure 16 shows the encoding structure and transmission method of HE-SIG-B according to an embodiment of the present invention. Figure 16(a) shows the encoding structure of HE-SIG-B, and Figure 16(b) shows the transmission method of HE-SIG-B in a bandwidth of 40 MHz or more.

[0127] Referring to Figure 16(a), HE-SIG-B consists of common fields and user-specific fields. The detailed configuration of the common fields and user-specific fields is as described in the embodiment in Figure 13. Each user field in the user-specific field is arranged in the order of the users assigned to it from the array of resource units indicated by the RA field of the common field.

[0128] A user-specific field consists of multiple user fields, which are transmitted in units of user block fields. As mentioned above, a user block field is made up of a combination of two user fields, a CRC field, and a tail field. If the total number of user fields is odd, the last user block field contains one user field. Padding is added to the end of HE-SIG-B along the boundaries of the OFDM symbol.

[0129] Referring to Figure 16(b), HE-SIG-B is encoded separately in each 20MHz bandwidth. In this case, HE-SIG-B consists of up to two contents per 20MHz unit, namely HE-SIG-B content channel 1 and HE-SIG-B content channel 2. In Figure 16(b), each box represents a 20MHz bandwidth, and "1" and "2" within the box represent HE-SIG-B content channel 1 and HE-SIG-B content channel 2, respectively. Across the total bandwidth, each HE-SIG-B content channel is arranged in order of physical frequency band. That is, HE-SIG-B content channel 1 is transmitted in the lowest frequency band, and HE-SIG-B content channel 2 is transmitted in the next highest frequency band. This content channel configuration is repeated in the next highest frequency band through content duplication. For example, for channels 1 through 4 in ascending frequency order that constitute a total 80 MHz bandwidth, HE-SIG-B content channel 1 is transmitted on channels 1 and 3, and HE-SIG-B content channel 2 is transmitted on channels 2 and 4. Similarly, for channels 1 through 8 in ascending frequency order that constitute a total 160 MHz bandwidth, HE-SIG-B content channel 1 is transmitted on channels 1, 3, 5, and 7, and HE-SIG-B content channel 2 is transmitted on channels 2, 4, 6, and 8. If a terminal can decode HE-SIG-B content channel 1 via at least one channel and HE-SIG-B content channel 2 via at least one other channel, it can obtain information about the configuration of the MU PPDU for the total bandwidth. On the other hand, if the total bandwidth is 20 MHz, only one SIG-B content channel is transmitted.

[0130] Discrete channel assignment The discontinuous channel allocation method and signaling method according to embodiments of the present invention will be described below with reference to Figures 17 to 21. In embodiments of the present invention, discontinuous channel allocation means channel allocation in which the bandwidth occupied by the transmitted packets (i.e., PPDUs) includes at least one discontinuous channel (or discontinuous resource unit). However, a channel with a total bandwidth of 80+80MHz is considered a continuous channel, just like a channel with a total bandwidth of 160MHz. Therefore, in embodiments of the present invention, a discontinuous channel (or discontinuous PPDU) refers to a discontinuous channel excluding the 80+80MHz channel.

[0131] In the following embodiments and drawings, the P20 channel refers to the 20MHz main channel, the S20 channel to the 20MHz sub-channel, the S40 channel to the 40MHz sub-channel, and the S80 channel to the 80MHz sub-channel. Also, S40A refers to the first 20MHz channel that makes up the S40 channel, and S40B refers to the second 20MHz channel that makes up the S40 channel. Similarly, the S80A channel, S80B channel, S80C channel, and S80D channel refer to the first 20MHz channel, the second 20MHz channel, the third 20MHz channel, and the fourth 20MHz channel that make up the S80 channel, respectively.

[0132] In embodiments of the present invention, the sender (e.g., AP) signals discontinuous channel assignment information through embodiments or combinations thereof described through the drawings. The sender performs multi-channel CCA for broadband packet transmission. Here, broadband means a total bandwidth of 40 MHz or more, but the present invention is not limited thereto. Based on the results of the multi-channel CCA, the sender transmits the packet to at least one idle channel. If the packet is transmitted to a discontinuous channel, the sender signals discontinuous channel assignment information through the non-legacy preamble of the packet. In this way, the sender transmits a radio packet signaled with discontinuous channel assignment information. The receiver (e.g., STA) receives the radio packet and obtains the discontinuous channel assignment information from the received packet. The receiver decodes the received packet based on the obtained discontinuous channel assignment information. Here, the received packet is HE MU PPDU, but the present invention is not limited thereto.

[0133] Figure 17 shows a discontinuous channel assignment method according to one embodiment of the present invention. According to the embodiment in Figure 17, the position on which at least one of the HE-SIG-B content channels is transmitted is variable. In this case, the receiver should variably set the decoding channel for receiving the HE-SIG-B content channel. In the embodiment in Figure 17, it is assumed that HE-SIG-B content channel 1 is transmitted from channel P20, and the channel on which HE-SIG-B content channel 2 is transmitted is variable. However, depending on the order of the physical frequencies of channel P20 within channel P40, HE-SIG-B content channel 2 may also be transmitted from channel P20. In this case, the channel on which HE-SIG-B content channel 1 is transmitted may be variable depending on the channel configuration. The discontinuous channel assignment information according to the embodiment of the present invention supports at least some of the channel configurations shown in Figure 17.

[0134] Figure 17(a) shows a channel configuration in which only the P20 channel is allocated within the P80 (Primary 80MHz) bandwidth. In this case, HE-SIG-B content channel 2 is not transmitted in the P80 bandwidth. Figure 17(b) shows a channel configuration in which the P40 channel is basically allocated within the P80 bandwidth. In this case, both HE-SIG-B content channel 1 and HE-SIG-B content channel 2 are transmitted via at least the P40 channel. Depending on the embodiment, a discontinuous channel may be used to which one of the two 20MHz channels of the S40 channel is allocated, i.e., the S40A channel or the S40B channel. When both the S40A channel and the S40B channel are allocated, a continuous channel with an 80MHz or 160MHz bandwidth is configured.

[0135] Figure 17(c) shows a channel configuration in which only the P20 channel and S40 channel are allocated from the P80 bandwidth. In this case, HE-SIG-B content channel 1 is transmitted via the P20 channel and the S40A channel, and HE-SIG-B content channel 2 is transmitted via the S40B channel. In the embodiment shown in Figure 17(c), HE-SIG-B content channel 1 and HE-SIG-B content channel 2 are transmitted according to the HE-SIG-B content channel transmission rules according to the embodiment of the present invention.

[0136] On the other hand, due to the bit limit of the HE-SIG-A bandwidth field, the bandwidth field indicates only a portion of the channel configuration. If the bandwidth field consists of 3 bits, it indexes four types of additional discontinuous channel assignment information. According to an embodiment of the present invention, the bandwidth field indicates the total bandwidth information through which the PPDU is transmitted, and some channel information that is punctured within the total bandwidth. In this case, the total bandwidth is one of either an 80 MHz bandwidth or a 160 MHz (or 80 + 80 MHz) bandwidth. According to one embodiment of the present invention, the bandwidth field indexes the puncturing of the S20 channel shown in Figure 17(c) and the puncturing of at least one of the two 20 MHz channels of the S40 channel shown in Figure 17(b).

[0137] According to an embodiment of the present invention, in a channel configuration indicated by the bandwidth field of HE-SIG-A, additional puncturing information is indicated via the RA field of HE-SIG-B. For example, if the bandwidth field indicates puncturing of one of the two 20MHz channels of the S40 channel with a total bandwidth of 80MHz (the third and fifth channel configurations in Figure 17(b)), the resource unit allocation field indicates which 20MHz channel of the S40 channel will be punctured. Also, if the bandwidth field indicates puncturing of at least one of the two 20MHz channels of the S40 channel with a total bandwidth of 160MHz or 80+80MHz (the second, fourth, and sixth channel configurations in Figure 17(b)), the resource unit allocation field indicates which 20MHz channel of the S40 channel will be punctured. In addition, if the bandwidth field indicates puncturing of at least one of the two 20MHz channels of the S40 channel with a total bandwidth of 160MHz or 80+80MHz (the second, fourth, and sixth channel configurations in Figure 17(b)), the resource unit allocation field indicates additional puncturing of the S80 channel. Also, if the bandwidth field indicates puncturing of the S20 channel with a total bandwidth of 160MHz or 80+80MHz (the second channel configuration in Figure 17(c)), the resource unit allocation field indicates additional puncturing of the S80 channel.

[0138] In this way, channels instructed to be punctured are not assigned to users. A terminal receiving a discontinuous PPDU obtains the total bandwidth information through which the PPDU is transmitted, and the channel information to be punctured within that total bandwidth, via the bandwidth field of HE-SIG-A of the PPDU. The terminal also obtains additional channel puncturing information via the RA field of HE-SIG-B of the PPDU. The terminal decodes the PPDU based on the discontinuous channel assignment information thus obtained.

[0139] Figure 18 shows a broadband approach method according to one embodiment of the present invention. After the transmission of a previous PPDU has ended, a terminal with data to transmit performs a backoff procedure on the P20 channel. The backoff procedure is initiated if the P20 channel is idle during the AIFS time. The terminal acquires a backoff counter within the competition window CW range for the backoff procedure. The terminal performs a CCA and decrements the backoff counter by one if the channel is idle. If the channel is occupied, the terminal suspends the backoff procedure and, if the channel is still idle, resumes the backoff procedure after the AIFS time. Once the backoff counter has expired via the backoff procedure, the terminal transmits the data. At this time, before the backoff counter expires, the terminal performs a CCA on a subchannel for transmitting data during the PIFS time.

[0140] The embodiment in Figure 18 shows a situation where the S40A channel and S80B channel are occupied within the 160MHz band where CCA is performed. If at least a portion of the subchannels where CCA is performed are occupied, the terminal's PPDU transmission bandwidth is determined based on the physical layer CCA indication information. The physical layer CCA indication information is represented by the PHY-CCA.indication primitive defined in the wireless LAN standard.

[0141] More specifically, PHY-CCA.indication is a primitive used by PHY to display the current state of a channel (or medium) to a local MAC entity, and includes a state indicator and a channel indicator. The state indicator indicates whether the channel is occupied or idle. If the channel evaluation by the physical hierarchy determines that the channel is unavailable, the value of the state indicator is set to occupied. Otherwise, the value of the state indicator is idle. The channel indicator indicates a set of channels that include occupied channels. If the value of the state indicator for a particular set of channels is idle, the corresponding channel indicator will no longer exist in the PHY-CCA.indication primitive.

[0142] Figure 18(a) shows a broadband approach method according to a first embodiment of the present invention. According to the first embodiment of the present invention, physical hierarchical CCA display information is represented by the PHY-CCA.indication primitive defined in the legacy wireless LAN system. That is, the channel indicator of the PHY-CCA.indication primitive indicates only one of four values: primary, secondary, secondary40, and secondary80. Thus, the channel indicator of the PHY-CCA.indication primitive indicates the first channel set containing the occupied channel(s) in the channel set order of P20 channel, S20 channel, S40 channel, and S80 channel. According to the embodiment in Figure 18(a), the channel indicator of the PHY-CCA.indication primitive indicates the S40 channel, which contains the occupied S40A channel. That is, the physical hierarchical reports PHY-CCA.indication(BUSY, {secondary40}) as the MAC hierarchical. The terminal transmits PPDU via a 40MHz bandwidth (i.e., P40 channel) which combines the P20 channel and S20 channel that have been identified as idle.

[0143] However, for MU PPDU transmission via discontinuous channel assignment as described in Figure 17, more detailed transmission of physical hierarchical CCA indication information is required. For this purpose, Figure 18(b) shows a broadband approach method according to a second embodiment of the present invention. According to the second embodiment of the present invention, physical hierarchical CCA indication information is represented by a newly defined PHY-CCA.indication primitive. According to the second embodiment of the present invention, the unit of channel set in which CCA results are reported is subdivided into each 20MHz channel. That is, the channel indicator of the PHY-CCA.indication primitive indicates one or more 20MHz channels of primary, secondary, secondary40A, secondary40B, secondary80A, secondary80B, secondary80C, secondary80D, or a similar form.

[0144] According to an embodiment of the present invention, the channel indicator of the PHY-CCA.indication primitive reports all of the eight 20MHz channels that constitute the 160MHz bandwidth and are determined to be occupied. In the embodiment shown in Figure 18(b), the channel indicator of the PHY-CCA.indication primitive indicates the occupied S40A and S80B channels. In other words, the physical layer reports PHY-CCA.indication(BUSY, {secondary40A, secondary80B}) to the MAC layer. The terminal transmits the PPDU using channels that are not occupied. Referring to Figure 18(b), the terminal transmits the discontinuous PPDU via the remaining channels (i.e., P20, S20, S40B, S80A, S80C, and S80D) excluding the S40A and S80B channels which are determined to be occupied.

[0145] According to another embodiment of the present invention, the CCA result values ​​for each 20MHz channel are reported in bitmap representation. That is, the channel indicator of the PHY-CCA.indication primitive indicates the occupied / unoccupied state of each 20MHz channel in bitmap form. For example, the channel indicator of the PHY-CCA.indication primitive consists of an 8-bit bitmap, where each bit is set to 1 if the corresponding 20MHz channel is occupied and to 0 if the corresponding 20MHz channel is unoccupied. In this case, the first to eighth bits of the bitmap indicate the occupied / unoccupied state of each of the eight 20MHz channels in order from the lowest frequency to the highest frequency within the 160MHz (80+80MHz) bandwidth.

[0146] According to an additional embodiment of the present invention, the physical layer reports the 20MHz channel-specific CCA result value only when the P20 channel is idle. That is, the channel indicator of the PHY-CCA.indication primitive indicates all the 20MHz subchannels(etc.) that are determined to be occupied from among the eight 20MHz channels that make up the 160MHz bandwidth, only when the P20 channel is idle. Furthermore, if the 20MHz channel-specific CCA result value is reported in a bitmap representation, the bit corresponding to the P20 channel in the bitmap is set to 0. If the P20 channel is occupied, the channel indicator of the PHY-CCA.indication primitive does not indicate subchannel information in 20MHz units. That is, the channel indicator of the PHY-CCA.indication primitive indicates only the primary, which is the first channel set containing the occupied channels(etc.), as in legacy wireless LAN systems.

[0147] Figure 19 shows one embodiment of a BQRP and BQR exchange and signaling method for transmitting discontinuous PPDUs. Referring to Figure 19, an AP attempting to transmit a DL MU PPDU performs a CCA at the physical layer and transmits the DL MU PPDU using channels determined to be idle based on the CCA results. In one embodiment, an MU-RTS frame is transmitted to one or more STAs before the DL MU PPDU is transmitted, and an sCTS frame is transmitted from the STA that received the MU-RTS frame. However, MU-RTS is transmitted only in the form of a PPDU with a continuous channel allocation basis, such as non-HT, non-HT duplicate, or HE SU PPDU. Therefore, as in the embodiment of Figure 19, if the S40A channel and S80B channel are occupied, MU-RTS is transmitted only via the 40MHz band including the P20 channel and S20 channel (i.e., the P40 channel). The AP receives sCTS frames transmitted from the STA in response to MU-RTS frames, but the exchange of MU-RTS and sCTS frames alone is not enough to determine the available channels of each STA.

[0148] Therefore, according to one embodiment of the present invention, in order to facilitate efficient resource allocation for MU PPDU transmission, the AP transmits a BQRP (Bandwidth Query Report Poll), and the STA transmits a BQR (Bandwidth Query Report) in response thereto. The BQR includes an available channel bitmap field indicating the available channel information of the STA in question. According to one embodiment, the BQR is carried via the control field of the MAC header. The STA implicitly carries the BQR via the BQR control field of the frame transmitted to the AP, or explicitly carries the BQR via the frame transmitted in response to the AP's BQRP trigger frame. According to an embodiment of the present invention, a BQR transmitted in response to a BQRP trigger frame is referred to as a solicited BQR, and a BQR transmitted regardless of the reception of a BQRP trigger frame is referred to as an unsolicited BQR.

[0149] In one embodiment, the AP transmits BQRP frames using the MU PPDU format, which is capable of transmission via the discontinuous channel allocation infrastructure. Based on the BQR received from each STA, the AP determines whether each channel is available to the corresponding STA. Through this BQRP / BQR transmission sequence, the AP confirms the available channel information of the STAs and performs DL MU PPDU transmission via the discontinuous channel allocation infrastructure. Referring to the embodiment in Figure 19, the AP transmits BQRP to STA1 via channel P40, to STA2 via channel S40B, to STA3 via channel S80A, to STA4 via channel S80C, and to STA5 via channel S80D, respectively, from the channels determined to be idle. The BQRP transmitted to STA1, STA2, STA3, STA4, and STA5 are carried via discontinuous MU PPDU. The AP receives BQR from STA1, STA3, and STA5 as a response to the BQRP. Therefore, the AP identifies that channel P40 is available to STA1, channel S80A is available to STA3, and channel S80D is available to STA5. However, the AP cannot receive a BQR as a response to BQRP from STA2 and STA4. Therefore, the AP identifies that channel S40B is not available to STA2, and channel S80C is not available to STA4. Based on the available channel information for each STA thus collected, the AP performs DL MU PPDU transmission.

[0150] Figure 20 shows another embodiment of the BQR transmission and signaling method for transmitting discontinuous PPDUs. As described above, the STA implicitly carries the BQR via the BQR control field of the frame transmitted to the AP. The AP checks the available channel information of each STA as it goes along via the unsolicited BQR received from the STA and performs DL MU PPDU transmission on a discontinuous channel allocation basis.

[0151] First, referring to Figure 20(a), the BQR is transmitted via the UL SU PPDU. An STA attempting to transmit the UL SU PPDU performs a CCA at the physical layer and transmits the UL SU PPDU using a channel determined to be idle based on the CCA results. However, the HE SU PPDU is transmitted only on a continuous channel allocation infrastructure. Therefore, as in the embodiment of Figure 20(a), if the S40A channel and S80B channel are occupied, the UL SU PPDU is transmitted via the 40MHz band including the P20 channel and S20 channel. In this case, the BQR is carried via the BQR control field of the frame transmitted via the UL SU PPDU. The BQR includes available channel information based on the CCA sensed by the STA.

[0152] Next, referring to Figure 20(b), the BQR is transmitted via an HE Trigger-based (TB) PPDU. An STA attempting to transmit an HE TB PPDU performs a CCA at the physical layer and transmits the HE TB PPDU using channels determined to be idle based on the CCA results. In this process, the BQR is carried via the BQR control field of the frame transmitted through the HE TB PPDU. The BQR includes available channel information based on the CCA results perceived by the STA.

[0153] Thus, an AP that receives a UL SU PPDU or HE TB PPDU containing a BQR checks the available channel information of the corresponding STA and then transmits a DL PPDU. On the other hand, the BQR indicates the available channel information through various embodiments. Specific embodiments of this will be explained with reference to Figure 21.

[0154] Figure 21 shows the configuration of a BQR according to one embodiment of the present invention. According to the embodiment of the present invention, available channel information is represented in the BQR via an available channel bitmap field. According to one embodiment, the BQR includes a bandwidth indicator field and an available channel bitmap field (or a bandwidth bitmap field). However, in some embodiments, the bandwidth indicator field may be omitted from the BQR.

[0155] The bandwidth indication field shows the total bandwidth over which the available channel information is carried. In one embodiment, the bandwidth indication field consists of 2 bits and indicates one of the following: 20MHz, 40MHz, 80MHz, and 160MHz (including 80+80MHz). The available channel bitmap field consists of 8 bits and indicates the availability (or occupied / unavailable state) of each 20MHz channel. If the BQR reports available channel information with a total bandwidth of 20MHz, the bandwidth indication field indicates 20MHz (or the P20 channel). If the BQR reports available channel information with a total bandwidth of 40MHz, the bandwidth indication field indicates 40MHz (or the P40 channel). In this case, the first and second bits of the available channel bitmap field indicate the availability of each of the two 20MHz channels in order from the lowest frequency to the highest frequency within the 40MHz bandwidth. Next, if the BQR reports available channel information for a total bandwidth of 80 MHz, the bandwidth indication field indicates 80 MHz (or P80 channel). In this case, the first four bits of the available channel bitmap field indicate the availability of each of the four 20 MHz channels, ordered from the lowest frequency to the highest frequency within the 80 MHz bandwidth. Next, if the BQR reports available channel information for a total bandwidth of 160 MHz (80 + 80 MHz), the bandwidth indication field indicates 160 MHz (80 + 80 MHz) (or P160 channel). In this case, the first eight bits of the available channel bitmap field indicate the availability of each of the eight 20 MHz channels, ordered from the lowest frequency to the highest frequency within the 160 MHz (80 + 80 MHz) bandwidth.

[0156] On the other hand, the BQR may include only the available channel bitmap field without a bandwidth indication field. In this case, the available channel bitmap field consists of 8 bits and indicates the availability (or occupied / idle state) of each 20MHz channel. Depending on the STA's CCA performance capability, if there are 20MHz channels for which CCA is not being performed, the bit value of the available channel bitmap field corresponding to that channel is set to 1 (i.e., occupied).

[0157] According to one embodiment of the present invention, the BQR indicates available channel information in various ways. According to the first embodiment of the present invention, the STA explicitly signals bandwidth information for which it was able to perform CCA before transmitting the PPDU containing the BQR via a bandwidth indication field, and indicates the availability of each channel within that bandwidth in the available channel bitmap. For example, if the STA performed CCA only on the 40MHz bandwidth before transmitting the 40MHz PPDU, the bandwidth indication field would indicate 40MHz, and the available channel bitmap field would carry only the CCA result values ​​for two 20MHz channels. However, if the STA performed CCA on a 160MHz bandwidth wider than the bandwidth of the PPDU before transmitting the 40MHz PPDU, the bandwidth indication field would indicate 160MHz, and the available channel bitmap field would carry the CCA result values ​​for eight 20MHz channels. In such embodiments, the STA autonomously sets the indicated bandwidth of the BQR's available channel bitmap field based on its own CCA performance capability.

[0158] Next, according to a second embodiment of the present invention, the STA performs a CCA on the entire bandwidth in which the BQRP trigger frame is received or the entire bandwidth in which the PPDU containing the BQR is transmitted, and indicates the availability of each channel within that bandwidth using the available channel bitmap. In this case, since the bandwidth information to which the available channel information is transmitted is obvious to the sender and receiver, the bandwidth indication field may be omitted in the BQR. If there is a 20MHz channel in the entire bandwidth in which the PPDU is transmitted that has not been CCA performed according to the STA's CCA performance capability, the STA does not transmit an unsolicited BQR. According to another embodiment, if there is a 20MHz channel in the entire bandwidth in which the PPDU is transmitted that has not been CCA performed according to the STA's CCA performance capability, the bit value of the available channel bitmap field corresponding to that channel is set to 1 (i.e., occupied).

[0159] Next, according to a third embodiment of the present invention, the STA performs a CCA on the entire bandwidth operated by the BSS to which the STA is coupled, and indicates the availability of each channel within that bandwidth using an available channel bitmap. If the bandwidth on which the STA can perform CCA is smaller than the overall bandwidth operated by the BSS, depending on the STA's CCA performance capability, the availability of each channel within the bandwidth on which the STA can perform CCA is indicated using the available channel bitmap. In other words, regardless of whether the BQRP trigger frame is received in the overall bandwidth or the PPDU containing the BQR is transmitted, the STA indicates the availability of each channel using an available channel bitmap based on the smaller of the overall bandwidth operated by the BSS and the bandwidth on which the STA can perform CCA. In this case, since the bandwidth information on which the available channel information is transmitted is obvious to the sender and receiver, the bandwidth indication field may be omitted in the BQR. Therefore, regardless of the transmission bandwidth of the PPDU carrying the BQRP or BQR, the AP transmits the DL MU PPDU based on the STA's available channel information within the overall bandwidth.

[0160] Although the present invention has been described using wireless LAN communication as an example, as described above, the present invention is not limited to this and is equally applicable to other communication systems such as cellular communication. Furthermore, although the methods, apparatus, and systems of the present invention have been described in relation to specific embodiments, some or all of the components and operations of the present invention can be embodied using a computer system having a general-purpose hardware architecture.

[0161] The embodiments of the present invention described above can be embodied through a variety of means. For example, embodiments of the present invention can be embodied through hardware, firmware, software, or a combination thereof.

[0162] In the case of hardware implementation, the method according to the embodiment of the present invention is implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, microprocessors, etc.

[0163] In the case of implementation by firmware or software, the method according to the embodiment of the present invention is implemented in the form of a module, procedure, or function that performs the functions or operations described above. The software code is stored in memory and implemented by a processor. The memory is located inside or outside the processor and exchanges data with the processor by various already known means.

[0164] The above description of the present invention is illustrative, and a person with ordinary skill in the art to which the invention pertains should understand that it can be easily modified into other specific forms without altering the technical idea or essential features of the invention. Therefore, the above embodiments should be interpreted as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0165] The scope of the present invention is indicated by the claims described below rather than by the detailed description above, and all modifications or altered forms derived from the meaning and scope of the claims and the concept of equivalents thereto should be interpreted as being included within the scope of the present invention. [Industrial applicability]

[0166] Although various embodiments of the present invention have been described primarily in relation to IEEE 802.11 systems, it is applicable to a wide variety of other forms of mobile communication devices, mobile communication systems, and the like.

Claims

1. A wireless communication terminal, Communications Department and, A processor that processes signals transmitted and received via the communication unit, The aforementioned processor, The communication unit receives a HE MU PPDU (high efficiency multi-user PHY protocol data unit), and the preamble of the HE MU PPDU includes HE-SIG-A (High Efficiency Signal A field) and HE-SIG-B (High Efficiency Signal B field). Based on the information obtained from the HE-SIG-A, the received HE MU PPDU is decoded. The configuration of the HE-SIG-B is a wireless communication terminal identified based on information obtained from at least one subfield of the HE-SIG-A.

2. If the SIG-B compression field of HE-SIG-A instructs MU-MIMO transmission across the entire bandwidth and there is no common field in HE-SIG-B, The wireless communication terminal according to claim 1, wherein the configuration of the user identification field of HE-SIG-B is identified based on information obtained from at least one subfield of HE-SIG-A.

3. The wireless communication terminal according to claim 2, wherein if the SIG-B compression field of the HE-SIG-A instructs overall bandwidth MU-MIMO transmission, the configuration of the user identification field of the HE-SIG-B is identified based on the number of MU-MIMO users instructed from the HE-SIG-A.

4. The user fields that constitute the user identification field of HE-SIG-B include user fields for MU-MIMO assignment and user fields for non-MU-MIMO assignment. If the number information of the MU-MIMO users indicates two or more users, the user identification field of the HE-SIG-B consists of the user field for MU-MIMO assignment. The wireless communication terminal according to claim 3, wherein if the number information of MU-MIMO users indicates one user, the user identification field of the HE-SIG-B consists of one user field for non-MU-MIMO assignment.

5. The user field for MU-MIMO allocation includes a spatial configuration field that indicates the total number of spatial streams in the MU-MIMO allocation and the number of spatial streams for each terminal in the MU-MIMO allocation. The wireless communication terminal according to claim 4, wherein the user field for non-MU-MIMO assignment includes an NSTS (Number of Spatial Streams) field.

6. The wireless communication terminal according to claim 4, wherein the user field for non-MU-MIMO allocation is a user field of an OFDMA (Orthogonal Frequency Division Multiple Access) allocation base.

7. The wireless communication terminal according to claim 3, wherein if the SIG-B compression field of the HE-SIG-A instructs overall bandwidth MU-MIMO transmission, the number of MU-MIMO users is indicated in the HE-SIG-A by the number field of the HE-SIG-B symbol.

8. The HE-SIG-A includes an uplink / downlink field that indicates whether the PPDU is transmitted uplink or downlink, The wireless communication terminal according to claim 1, wherein at least one subfield of HE-SIG-A of the PPDU indicates or is set to indicate different information based on the value indicated by the uplink / downlink field.

9. If the aforementioned uplink / downlink field indicates downlink transmission, the specific value of the bandwidth field of HE-SIG-A indicates a preset discontinuous bandwidth. The wireless communication terminal according to claim 8, wherein if the uplink / downlink field indicates uplink transmission, the specific value of the bandwidth field of HE-SIG-A indicates a preset narrow bandwidth.

10. The wireless communication terminal according to claim 9, wherein the preset narrow bandwidth includes at least one of left-106-tone and right-106-tone.

11. If the aforementioned uplink / downlink fields indicate downlink transmission, the SIG-B compression field of HE-SIG-A indicates whether or not to perform MU-MIMO transmission of the entire bandwidth in which no common fields exist in the HE-SIG-B field. The wireless communication terminal according to claim 8, wherein if the uplink / downlink field indicates uplink transmission, the SIG-B compression field of HE-SIG-A always indicates that there is no common field in the HE-SIG-B field.

12. When the SIG-B compression field of HE-SIG-A indicates the compression mode of the HE-SIG-B field, If the aforementioned uplink / downlink field indicates downlink transmission, the HE-SIG-B symbol count field of HE-SIG-A indicates the number of MU-MIMO users. The wireless communication terminal according to claim 8, wherein if the uplink / downlink field indicates uplink transmission, the HE-SIG-B symbol count field of HE-SIG-A indicates the number of OFDM symbols in the HE-SIG-B field.

13. A wireless communication method for wireless communication terminals, The steps include receiving a HE MU PPDU, and the preamble of the HE MU PPDU includes HE-SIG-A and HE-SIG-B. The step includes decoding the received HE MU PPDU based on the information obtained from the HE-SIG-A, The configuration of HE-SIG-B is a wireless communication method identified based on information obtained from at least one subfield of HE-SIG-A.

14. If the SIG-B compression field of HE-SIG-A instructs MU-MIMO transmission across the entire bandwidth and there is no common field in HE-SIG-B, The wireless communication method according to claim 13, wherein the configuration of the user identification field of HE-SIG-B is identified based on information obtained from at least one subfield of HE-SIG-A.

15. The wireless communication method according to claim 14, wherein if the SIG-B compression field of the HE-SIG-A instructs overall bandwidth MU-MIMO transmission, the configuration of the user identification field of the HE-SIG-B is identified based on the number of MU-MIMO users instructed from the HE-SIG-A.

16. The user fields that constitute the user identification field of HE-SIG-B include user fields for MU-MIMO assignment and user fields for non-MU-MIMO assignment. If the number information of the MU-MIMO users indicates two or more users, the user identification field of the HE-SIG-B consists of the user field for MU-MIMO assignment. The wireless communication method according to claim 15, wherein if the number information of MU-MIMO users indicates one user, the user identification field of the HE-SIG-B consists of one user field for non-MU-MIMO assignment.

17. The user field for MU-MIMO allocation includes a spatial configuration field that indicates the total number of spatial streams in the MU-MIMO allocation and the number of spatial streams for each terminal in the MU-MIMO allocation. The wireless communication method according to claim 16, wherein the user field for non-MU-MIMO assignment includes an NSTS field.

18. The wireless communication method according to claim 16, wherein the user field for non-MU-MIMO assignment is a user field of OFDMA assignment base.

19. The wireless communication method according to claim 15, wherein if the SIG-B compression field of the HE-SIG-A instructs overall bandwidth MU-MIMO transmission, the number information of the MU-MIMO users is indicated in the HE-SIG-A by the number field of the HE-SIG-B symbols.

20. The HE-SIG-A includes an uplink / downlink field that indicates whether the PPDU is transmitted uplink or downlink, The wireless communication method according to claim 13, wherein at least one subfield of the HE-SIG-A of the PPDU indicates or is set to indicate different information based on the value indicated by the up / down field.

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