Wireless communication terminal and wireless communication method for multi-user EDCA operation

Abstract

The present invention relates to a wireless communication terminal and a wireless communication method for multi-user enhanced distributed channel access (EDCA) operation, and more particularly, to a wireless communication terminal and a wireless communication method for performing a combination of legacy EDCA operation and multi-user EDCA operation. To this end, the present invention provides a wireless communication terminal and a wireless communication method using the same, the wireless communication terminal including: a communication unit; and a processor that controls an operation of transmitting and receiving a wireless signal through the communication unit, wherein the processor updates an EDCA parameter for channel access, wherein the EDCA parameter is updated based on an EDCA parameter set selected from among a first EDCA parameter set and a second EDCA parameter set, and performs channel access based on the updated EDCA parameter.

Description

[0001] This application is a divisional application of patent application No. 201780058494.0 (PCT / KR2017 / 010529), filed with the China Patent Office on March 22, 2019, with an international application date of September 25, 2017, entitled "Wireless Communication Terminal and Wireless Communication Method for Multi-User EDCA Operation". Technical Field

[0002] The present invention relates to a wireless communication terminal and a wireless communication method for multi-user EDCA operation, and more specifically, to a wireless communication terminal and a wireless communication method for performing a combination of conventional EDCA operation and multi-user EDCA operation. Background Technology

[0003] In recent years, with the expansion of mobile device supply, wireless LAN technology, which can provide fast wireless internet services to mobile devices, has gained attention. Wireless LAN technology allows mobile devices, including smartphones, tablets, laptops, portable multimedia players, embedded devices, and more, to wirelessly access the internet in their homes, offices, or specific service areas based on short-range wireless communication technology.

[0004] Since using the 2.4 GHz frequency to support initial wireless LAN technology, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 has commercialized or developed various technical standards. First, IEEE 802.11b, using the 2.4 GHz band, supported a maximum communication speed of 11 Mbps. Compared to the significantly congested 2.4 GHz band, IEEE 802.11a, commercialized after IEEE 802.11b, used the 5 GHz band instead of 2.4 GHz to reduce interference and increased the communication speed to a maximum of 54 Mbps through the use of OFDM technology. However, a drawback of IEEE 802.11a is its shorter communication range compared to IEEE 802.11b. Furthermore, similar to IEEE 802.11b, IEEE 802.11g, using the 2.4 GHz band to achieve a maximum communication speed of 54 Mbps and satisfying backward compatibility, has attracted significant attention and, in terms of communication range, is superior to IEEE 802.11a.

[0005] Furthermore, IEEE 802.11n has been developed as a technical standard to overcome the communication speed limitations identified as a weakness in wireless LANs. IEEE 802.11n aims to improve network speed and reliability and extend the operating range of wireless networks. More specifically, IEEE 802.11n supports high throughput (HT), with data processing speeds of up to 540 Mbps or higher, and further, it is based on multiple-input multiple-output (MIMO) technology, where multiple antennas are used on both sides of the transmitting and receiving units to minimize transmission errors and optimize data speed. Additionally, the standard can use coding schemes that transmit multiple superimposed copies to increase data reliability.

[0006] With the active provision of wireless LANs and the further diversification of applications using wireless LANs, there has been a growing demand for new wireless LAN systems that support higher throughput (Very High Throughput (VHT)) than those supported by IEEE 802.11n. Among these, IEEE 802.11ac supports wide bandwidth (80 to 160 MHz) in the 5 GHz frequency band. The IEEE 802.11ac standard is defined only in the 5 GHz band, but initial 11ac chipsets even support operation in the 2.4 GHz band for backward compatibility with existing 2.4 GHz band products. Theoretically, according to this standard, wireless LAN speeds of at least 1 Gbps can be enabled across multiple stations, and maximum single-link speeds can reach at least 500 Mbps. This is achieved by extending the concepts of the wireless interface accepted by 802.11n, such as wider wireless bandwidth (maximum 160 MHz), more MIMO spatial streams (maximum 8), multi-user MIMO, and high-density modulation (maximum 256 QAM). Furthermore, IEEE 802.11ad has been offered as a solution for transmitting data using the 60GHz band instead of the existing 2.4GHz / 5GHz band. IEEE 802.11ad is a transmission standard that provides speeds up to 7Gbps using beamforming technology and is suitable for high bit-rate motion streaming, such as massive amounts of data or uncompressed HD video. However, its drawback is that the 60GHz band is difficult to penetrate obstacles, limiting its use to devices operating in close proximity.

[0007] Meanwhile, in recent years, as the next-generation wireless LAN standard following 802.11ac and 802.11ad, discussions have continued regarding technologies for providing efficient and high-performance wireless LAN communication in high-density environments. Specifically, in next-generation wireless LAN environments, with the presence of high-density stations and access points (APs), there is a need to provide communication with high spectral efficiency indoors / outdoors, and various technologies are required to achieve this communication. Summary of the Invention

[0008] Technical issues

[0009] The present invention aims to provide high-efficiency / high-performance wireless LAN communication in high-density environments as described above.

[0010] Furthermore, the present invention aims to manage and control parameters for multi-user EDCA operations in addition to conventional EDCA operations.

[0011] Technical solution

[0012] To achieve these objectives, the present invention provides the following wireless communication method and wireless communication terminal.

[0013] First, an exemplary embodiment of the present invention provides a wireless communication terminal, including: a communication unit; and a processor configured to control the transmission and reception of wireless signals through the communication unit, wherein the processor updates enhanced distributed channel access (EDCA) parameters for channel access, updates the EDCA parameters based on an EDCA parameter set selected from a first EDCA parameter set and a second EDCA parameter set, and performs channel access based on the updated EDCA parameters.

[0014] In this case, the second EDCA parameter set can be a multi-user (MU) EDCA parameter set, and when the EDCA parameters are updated based on the MU EDCA parameter set, the processor can use the parameter settings updated based on the MU EDCA parameter set to indicate the duration of the channel access execution MU EDCA timer.

[0015] According to an embodiment of the present invention, when the terminal does not participate in uplink multi-user (UL-MU) transmission, the processor can send a frame containing a suspended operation mode indication (OMI) information in which the UL-MU disable subfield indicates UL-MU operation, and when the processor receives an immediate response to the frame containing the OMI information from the OMI responder, the processor can set the MU EDCA timer to zero.

[0016] Furthermore, when an immediate response containing OMI information is received from an OMI responder, the processor can set the MU EDCA timer for all access categories to zero.

[0017] According to an embodiment, when the MU EDCA timer reaches zero, the processor can update the EDCA parameters based on the first EDCA parameter set recently received from the underlying wireless communication terminal associated with the terminal.

[0018] According to another embodiment, when the MU EDCA timer reaches zero, if the first EDCA parameter set has not been received from the underlying wireless communication terminal associated with the terminal, the processor can update the EDCA parameters based on a predetermined default EDCA parameter set.

[0019] In addition, the MU EDCA timer can be set to the value of the MU EDCA timer subfield of the MU EDCA parameter set most recently received from the underlying wireless communication terminal associated with the terminal.

[0020] Furthermore, at least one parameter of the second EDCA parameter set may have a value greater than that of the corresponding parameter of the first EDCA parameter set.

[0021] In addition, channel access can be performed based on the backoff process using a backoff timer obtained within the contention window of the corresponding access category, and the EDCA parameters can include a minimum and a maximum contention window value for setting the contention window.

[0022] Furthermore, the first EDCA parameter set and the second EDCA parameter set can be received via at least one of a beacon, a probe response, and an association response sent by the underlying wireless communication terminal associated with the terminal.

[0023] In addition, another exemplary embodiment of the present invention provides a wireless communication method for a wireless communication terminal, comprising: updating enhanced distributed channel access (EDCA) parameters for channel access, wherein the EDCA parameters are updated based on an EDCA parameter set selected from a first EDCA parameter set and a second EDCA parameter set; and performing channel access based on the updated EDCA parameters.

[0024] In this case, the second EDCA parameter set may be a multi-user (MU) EDCA parameter set, and when the EDCA parameters are updated based on the MU EDCA parameter set, the method further includes: using the parameter settings updated based on the MU EDCA parameter set to indicate the duration of the channel access to be performed by the MU EDCA timer.

[0025] According to an embodiment of the present invention, when the terminal does not participate in uplink multi-user (UL-MU) transmission, the method further includes: sending a frame containing Operation Mode Indication (OMI) information, wherein the UL-MU disable subfield in the OMI information indicates the suspension of UL-MU operation, and when an immediate response to the frame containing the OMI information is received from the OMI responder, the method further includes: setting the MU EDCA timer to zero.

[0026] In addition, when an immediate response containing OMI information is received from an OMI responder, setting the MU EDCA timer to zero includes setting the MU EDCA timer to zero for all access categories.

[0027] According to an embodiment, when the MU EDCA timer reaches zero, the update step includes updating the EDCA parameters based on a first set of EDCA parameters recently received from the underlying wireless communication terminal associated with the terminal.

[0028] According to another embodiment, when the MU EDCA timer reaches zero, the update step includes updating the EDCA parameters based on a predetermined default EDCA parameter set if a first EDCA parameter set has not yet been received from the basic wireless communication terminal associated with the terminal.

[0029] In addition, the MU EDCA timer can be set to the value of the MU EDCA timer subfield of the MU EDCA parameter set most recently received from the underlying wireless communication terminal associated with the terminal.

[0030] Furthermore, at least one parameter in the second EDCA parameter set has a value greater than that of the corresponding parameter in the first EDCA parameter set.

[0031] In addition, channel access can be performed based on the backoff process using a backoff timer obtained within the contention window of the corresponding access category, and the EDCA parameters can include a minimum and a maximum contention window value for setting the contention window.

[0032] Furthermore, the first EDCA parameter set and the second EDCA parameter set can be received via at least one of a beacon, a probe response, and an association response sent by the underlying wireless communication terminal associated with the terminal.

[0033] Beneficial effects

[0034] According to embodiments of the present invention, the switching between traditional EDCA operations and multi-user EDCA operations can be effectively managed.

[0035] According to embodiments of the present invention, it is possible to increase the overall resource utilization in a contention-based channel access system and improve the performance of a wireless LAN system. Attached Figure Description

[0036] Figure 1 The illustration shows a wireless LAN system according to an embodiment of the present invention.

[0037] Figure 2 The illustration shows a wireless LAN system according to another embodiment of the present invention.

[0038] Figure 3The illustration shows the configuration of a station according to an embodiment of the present invention.

[0039] Figure 4 The diagram illustrates the configuration of an access point according to an embodiment of the present invention.

[0040] Figure 5 This diagram illustrates the process of setting up a link between a STA and an AP.

[0041] Figure 6 The diagram illustrates the Carrier Sense Multiple Access (CSMA) / Collision Avoidance (CA) method used in wireless LAN communication.

[0042] Figure 7 The illustration shows the switching operation between the conventional EDCA mode and the multi-user EDCA mode according to an embodiment of the present invention.

[0043] Figure 8 The illustration shows the configuration of multi-user EDCA parameter set elements according to an embodiment of the present invention.

[0044] Figure 9 The illustration shows a method for sending a multi-user EDCA parameter set according to an embodiment of the present invention.

[0045] Figure 10 The illustration shows a method for disabling multi-user EDCA according to an embodiment of the present invention.

[0046] Figure 11 The illustration shows the configuration of the operation mode indicator element according to an embodiment of the present invention.

[0047] Figure 12 The diagram illustrates a method for controlling multi-user transmission based on operating mode indication information.

[0048] Figure 13 The illustration shows a method for disabling multi-user EDCA according to another embodiment of the present invention.

[0049] Figure 14 The illustration shows a method for disabling multi-user EDCA according to another embodiment of the present invention.

[0050] Figure 15 The illustration shows the configuration of the HE MU PPDU according to an embodiment of the present invention.

[0051] Figure 16 The illustration shows the configuration of a HE MU PPDU according to another embodiment of the present invention.

[0052] Figure 17 The illustration shows the configuration of the HE MU PPDU according to yet another embodiment of the present invention. Detailed Implementation

[0053] In consideration of the functionality of this invention, the terminology used in this specification employs currently widely used and common terms; however, the terminology may change according to the intent, habits, and emergence of new technologies of those skilled in the art. Furthermore, in certain cases, there are terms arbitrarily chosen by the applicant, and in such cases, their meaning will be described in the corresponding descriptive section of the invention. Therefore, it should be understood that the terminology used in this specification should be analyzed not only based on the name of the term, but also on its substantive meaning and the content of the entire specification.

[0054] Throughout this specification and the following claims, when an element is described as being “coupled” to another element, that element may be “directly coupled” to the other element or “electrically coupled” to the other element via a third element. Furthermore, unless explicitly stated otherwise, the words “comprising” and variations such as “including” or “includes” will be understood to implicitly include the stated element but do not exclude any other element. Additionally, limitations based on specific thresholds such as “or more” or “or less” may be appropriately replaced by “greater than” or “less than”, respectively.

[0055] This application claims priority and benefit to Korean Patent Applications 10-2016-0122488 and 10-2017-0020966 filed with the Korean Intellectual Property Office, and the embodiments and matters mentioned that form the basis of the priority described in the respective applications will be included in the specific embodiments of this application.

[0056] Figure 1 This diagram illustrates a wireless LAN system according to an embodiment of the present invention. The wireless LAN system includes one or more Basic Service Sets (BSSs), and a BSS represents a group of devices that have successfully synchronized with each other to communicate. Typically, a BSS can be divided into a Infrastructure BSS and Independent BSSs (IBSSs), and... Figure 1 The diagram shows the basic structure BSS between them.

[0057] As in Figure 1 As shown in the diagram, the infrastructure BSS (BSS1 and BSS2) includes one or more stations STA1, STA2, STA3, STA4 and STA5, access points PCP / AP-1 and PCP / AP-2 that provide distributed services, and a distribution system (DS) that connects multiple access points PCP / AP-1 and PCP / AP-2.

[0058] A station (STA) is a predetermined device comprising a Media Access Control (MAC) conforming to the IEEE 802.11 standard and a physical layer interface for wireless media, and broadly includes both non-access point (non-AP) stations and access point (AP) stations. Furthermore, in this specification, the term "terminal" may be used to refer to a non-AP STA, or an AP, or both. A station for wireless communication includes a processor and a communication unit, and according to this embodiment, may further include a user interface unit and a display unit. The processor can generate frames to be transmitted via a wireless network, or process frames received via a wireless network, and further performs various processes for controlling the station. Additionally, the communication unit is functionally connected to the processor and transmits and receives frames via the wireless network used for the station. According to the invention, "terminal" can be used as a term including user equipment (UE).

[0059] An access point (AP) is an entity that provides access to a distribution system (DS) via wireless media for its associated stations. In a BSS infrastructure, communication between non-AP stations is generally performed via the AP, but direct communication between non-AP stations is even permitted when a direct link is configured. In this invention, the AP is used as a concept encompassing a Personal BSS Coordination Point (PCP), and broadly can include concepts including a central controller, base station (BS), node B, base transceiver system (BTS), and site controller. In this invention, an AP can also be referred to as a base station wireless communication terminal. The term "base station wireless communication terminal" can be used broadly and includes APs, base stations, eNBs (i.e., e-node Bs), and transmission points (TPs). Furthermore, a base station wireless communication terminal can include various types of wireless communication terminals that allocate media resources and perform scheduling of communication with multiple wireless communication terminals.

[0060] Multiple infrastructure BSSs can be interconnected via a distributed system (DS). In this case, the multiple BSSs connected via the distributed system are called an extended service set (ESS).

[0061] Figure 2 The illustration shows a standalone BSS according to another embodiment of the present invention, which is a wireless LAN system. Figure 2 In the embodiments, the same as or corresponding to Figure 1 Repeated descriptions of certain embodiments will be omitted.

[0062] Because in Figure 2 The BSS3 shown in the diagram is an independent BSS and does not include an access point (AP). All stations STA6 and STA7 are not connected to the AP. Independent BSSs are not allowed to access the distributed system and form self-contained networks. Within an independent BSS, the corresponding stations STA6 and STA7 can be directly interconnected.

[0063] Figure 3 This is a block diagram illustrating the configuration of station 100 according to an embodiment of the present invention. (As shown in...) Figure 3 As shown in the figure, the station 100 according to an embodiment of the present invention may include a processor 110, a communication unit 120, a user interface unit 140, a display unit 150, and a memory 160.

[0064] First, the communication unit 120 transmits and receives wireless signals, such as wireless LAN packets, and can be embedded in the station 100 or provided as a peripheral. According to this embodiment, the communication unit 120 may include at least one communication module using different frequency bands. For example, the communication unit 120 may include communication modules with different frequency bands, such as 2.4 GHz, 5 GHz, and 60 GHz. According to one embodiment, the station 100 may include communication modules using a frequency band of 6 GHz or higher, and communication modules using a frequency band of 6 GHz or lower. The corresponding communication modules can perform wireless communication with the AP or external station according to the wireless LAN standard of the frequency band supported by the corresponding communication module. The communication unit 120 may operate only one communication module at a time, or operate multiple communication modules simultaneously, depending on the performance and requirements of the station 100. When the station 100 includes multiple communication modules, each communication module can be implemented by an independent component, or multiple modules can be integrated into a single chip. In embodiments of the invention, the communication unit 120 may represent a radio frequency (RF) communication module for processing RF signals.

[0065] Secondly, the user interface unit 140 includes various types of input / output devices provided in the station 100. That is, the user interface unit 140 can receive user input using various input devices, and the processor 110 can control the station 100 based on the received user input. Furthermore, the user interface unit 140 can execute outputs based on commands from the processor 110 using various output devices.

[0066] Next, the display unit 150 outputs an image on the display screen. The display unit 150 can output various display objects based on control commands from the processor 110, such as content executed by the processor 110 or a user interface. Furthermore, the memory 160 stores the control program and various result data used in the station 100. The control program may include the access program required for the station 100 to connect to the AP or an external station.

[0067] The processor 110 of the present invention can execute various commands or programs and process data in the station 100. Furthermore, the processor 110 can control various units of the station 100 and control data transmission / reception within the units. According to an embodiment of the present invention, the processor 110 can execute a program for accessing an AP stored in the memory 160 and receive communication configuration messages sent by the AP. Furthermore, the processor 110 can read information about the priority conditions of the station 100 included in the communication configuration messages and request access to the AP based on the information about the priority conditions of the station 100. The processor 110 of the present invention can represent the main control unit of the station 100, and according to this embodiment, the processor 110 can represent a control unit for individually controlling certain components of the station 100, such as the communication unit 120, etc. That is, the processor 110 can be a modem or modulator / demodulator for modulating wireless signals transmitted to the communication unit 120 and demodulating wireless signals received from the communication unit 120. The processor 110 controls various operations of wireless signal transmission / reception of the station 100 according to an embodiment of the present invention. Detailed embodiments thereof will be described below.

[0068] exist Figure 3 The station 100 illustrated in the diagram is a block diagram according to an embodiment of the present invention, where individual blocks are illustrated as logically distinct device elements. Therefore, the elements of the device can be installed in a single chip or multiple chips depending on the device design. For example, the processor 110 and the communication unit 120 can be implemented as a single chip or as separate chips. Furthermore, in embodiments of the present invention, certain components of the station 100, such as the user interface unit 140 and the display unit 150, can be selectively disposed in the station 100.

[0069] Figure 4 This is a block diagram illustrating the configuration of an AP 200 according to an embodiment of the present invention. (As shown in...) Figure 4 As illustrated in the figure, the AP 200 according to an embodiment of the present invention may include a processor 210, a communication unit 220, and a memory 260. Figure 4 In the AP200 components, and... Figure 2 The components of station 100 are the same or correspond to Figure 2 Repeated descriptions of parts of station 100 will be omitted.

[0070] refer to Figure 4 The AP 200 according to the invention includes a communication unit 220 that operates a BSS in at least one frequency band. (As in...) Figure 3As described in the embodiments, the communication unit 220 of AP 200 may also include multiple communication modules using different frequency bands. That is, AP 200 according to embodiments of the present invention may include two or more communication modules in different frequency bands, such as 2.4 GHz, 5 GHz, and 60 GHz. Preferably, AP 200 may include communication modules using frequency bands of 6 GHz or higher, and communication modules using frequency bands of 6 GHz or lower. Each communication module may perform wireless communication with the station according to the wireless LAN standard of the frequency band supported by the respective communication module. Communication unit 220 may operate only one communication module at a time, or operate multiple communication modules simultaneously, depending on the performance and requirements of AP 200. In embodiments of the present invention, communication unit 220 may represent a radio frequency (RF) communication module for processing RF signals.

[0071] Next, memory 260 stores the control program and various result data used in AP 200. The control program may include an access program for managing station access. Furthermore, processor 210 can control the various units of AP 200 and control data transmission / reception within the units. According to an embodiment of the invention, processor 210 can execute programs for accessing stations stored in memory 260 and send communication configuration messages for one or more stations. In this case, the communication configuration message may include information about access priority conditions for each station. Furthermore, processor 210 performs access configuration based on the station's access request. According to one embodiment, processor 210 may be a modem or modulator / demodulator for modulating wireless signals transmitted to communication unit 220 and demodulating wireless signals received from communication unit 220. Processor 210 controls various operations, such as wireless signal transmission / reception of AP 200, according to embodiments of the invention. Detailed embodiments thereof will be described below.

[0072] Figure 5 This is a schematic diagram illustrating the process of setting up the link between the STA and the AP.

[0073] refer to Figure 5 In a broad sense, the link between STA 100 and AP 200 is set up through three steps: scanning, authentication, and association. First, the scanning step is where STA 100 obtains access information from the BSS operated by AP 200. Methods for performing the scan include a passive scanning method, in which AP 200 obtains information by periodically sending beacon messages (S101), and an active scanning method, in which STA 100 sends a probe request to AP (S103) and obtains access information by receiving probe responses from AP (S105).

[0074] STA 100, having successfully received wireless access information during the scanning step, performs an authentication step (S107b) by sending an authentication request (S107a) and receiving an authentication response from AP 200. After performing the authentication step, STA 100 performs an association step by sending an association request (S109a) and receiving an association response from AP 200 (S109b). In this specification, association primarily refers to wireless association; however, the invention is not limited thereto, and association can broadly include both wireless and wired associations.

[0075] Meanwhile, the 802.1X-based authentication step (S111) and the IP address acquisition step via DHCP (S113) can be performed separately. Figure 5 In this context, authentication server 300 is the server that handles 802.1X-based authentication for STA 100, and can exist in a physical association with AP 200 or as a standalone server.

[0076] Figure 6 The diagram illustrates the Carrier Sense Multiple Access (CSMA) / Collision Avoidance (CA) method used in wireless LAN communication.

[0077] Terminals performing wireless LAN communication check if the channel is busy by performing carrier sensing before transmitting data. When a wireless signal with a predetermined strength or higher is sensed, the corresponding channel is determined to be busy, and the terminal delays transmission on that channel. This process is called Clear Channel Assessment (CCA), and the level at which the corresponding signal is sensed is called the CCA threshold. When a wireless signal received by the terminal with a strength of CCA threshold or higher indicates that the terminal is a receiver, the terminal processes the received radio signal. Conversely, when no wireless signal is sensed on the corresponding channel, or when a wireless signal with a strength less than the CCA threshold is sensed, the channel is determined to be idle.

[0078] When the channel is determined to be idle, each terminal with data to transmit performs a backoff procedure after the inter-frame space (IFS) time, such as the Arbitrated IFS (AIFS), PCF IFS (PIFS), etc., has elapsed, depending on the situation of each terminal. According to this embodiment, AIFS can be used as a component to replace the existing DCF IFS (DIFS). As long as a random number, i.e., a backoff counter, is determined by the corresponding terminal during the idle interval of the channel, each terminal prepares as the time slot time decreases, and terminals that have completely exhausted the time slot attempt to transmit on the corresponding channel. Therefore, the interval at which each terminal performs the backoff procedure is called the contention window interval.

[0079] When a specific terminal successfully accesses the channel, it can transmit data via that channel. However, when a terminal attempting to transmit conflicts with another terminal, the conflicting terminals are assigned a new random number (i.e., a backoff counter) to re-execute the backoff process separately. According to one embodiment, it can be determined that the random number reassigned to each terminal is within the range (2*CW), which is twice the range (contention window, CW) of the random number previously used by the corresponding terminal. Simultaneously, each terminal accesses the channel again in the next contention window interval by re-executing the backoff process, and in this case, each terminal begins the backoff process from the time slot period maintained in the previous contention window interval. In this way, terminals performing wireless LAN communication can avoid conflicts with each other for a specific channel.

[0080] Multi-user transmission

[0081] When using Orthogonal Frequency Division Multiple Access (OFDMA) or Multiple-Input Multiple-Output (MIMO), a wireless communication terminal can simultaneously transmit data to one or more wireless communication terminals. Furthermore, one or more wireless communication terminals can simultaneously transmit data to each other. For example, downlink multi-user (DL-MU) transmission where the AP simultaneously transmits data to one or more STAs, and uplink multi-user (UL-MU) transmission where one or more STAs simultaneously transmit data to the AP can be performed.

[0082] To perform UL-MU transmission, the resource units to be used by each STA and the transmission start time for each STA performing uplink transmission should be determined. According to embodiments of the invention, the UL-MU transmission process can be managed by the AP. UL-MU transmission can be performed in response to a trigger frame sent by the AP. The trigger frame indicates the UL-MU transmission during the SIFS time period following the completion of the transmission of the PHY Protocol Data Unit (PPDU) carrying the trigger frame. Furthermore, the trigger frame delivers resource unit allocation information for UL-MU transmission. When the AP sends the trigger frame, one or more STAs transmit uplink data through each allocated resource unit at the time specified in the trigger frame. UL-MU transmission in response to the trigger frame is performed by trigger-based PPDUs. After completing uplink data transmission, the AP sends an ACK to the STA that successfully transmitted uplink data. In this case, the AP can send a predetermined multi-STA block ACK (M-BA) as an ACK for one or more STAs.

[0083] In non-traditional wireless LAN systems, a specific number, such as 26, 52, or 106 tones, can be used as resource units for subchannel-based access in a 20MHz band. Therefore, the trigger frame can indicate the identification information of each STA participating in the UL-MU transmission and the information of the allocated resource units. The STA identification information includes at least one of the STA's Association ID (AID), a partial AID, and a MAC address. Furthermore, the resource unit information includes the size and layout information of the resource unit.

[0084] Multi-user Enhanced Distributed Channel Access (EDCA)

[0085] Wireless communication terminals using unlicensed frequency bands, as in wireless LAN systems, can access the channel through a contention process. A terminal with data to transmit does not immediately attempt to transmit, but instead attempts to transmit after a predetermined waiting time (e.g., AIFS[AC]) specified for each access class (AC) to which each service belongs. If the channel switches from a busy state to an idle state, the terminal performs a backoff procedure after the specified waiting time. For the backoff procedure, the terminal sets a random number obtained from the contention window (i.e., CW[AC]) of the corresponding access class into a backoff timer (or backoff counter). The terminal decrements the backoff timer when the channel is idle and can perform transmission when the backoff timer reaches zero. Such specified waiting times (i.e., AIFS[AC]), contention windows (i.e., CW[AC]), minimum contention window value (i.e., CWmin), and maximum contention window value for channel access (i.e., CWmax) can be maintained and managed for each access class.

[0086] As described above, UL-MU transmission can be performed in non-traditional wireless LAN systems. An AP triggers uplink transmissions for one or more STAs. In this case, the AP accesses the channel to trigger UL-MU transmission. Alternatively, each STA can access the channel separately to transmit its own data. If a STA's UL-MU transmission is triggered during its individual access process, the STA can suspend the individual access process and perform the UL-MU transmission. Therefore, compared to traditional terminals, STAs have a high competitive advantage because they have redundant transmission opportunities through individual transmissions and UL-MU transmissions for the same service. Furthermore, because APs and STAs simultaneously compete for the service transmission of a specific STA, the probability of conflict may increase.

[0087] To address this issue, according to embodiments of the invention, a separate EDCA parameter set can be used for STAs participating in UL-MU transmission. The EDCA parameter set is a set of parameters for channel access, including the AIFSN, CWmin, and CWmax of the corresponding AC. AIFSN represents the number of time slots after the SIFS included in the specified waiting time (i.e., AIFS). In embodiments of the invention, the EDCA parameter set used in conventional wireless LAN systems is referred to as the conventional EDCA parameter set (or the first EDCA parameter set), and the separate EDCA parameter set for STAs participating in UL-MU transmission in non-conventional wireless LAN systems is referred to as the multi-user (MU) EDCA parameter set (or the second EDCA parameter set). Furthermore, EDCA parameter set and EDCA parameter set elements can be used as terms with the same meaning. The conventional EDCA parameter set and the MU EDCA parameter set can be received via at least one of a beacon, a probe response, and an association response sent by the AP associated with the STA.

[0088] According to embodiments of the present invention, at least one parameter of the MU EDCA parameter set may have a value greater than that of the corresponding parameter in a conventional EDCA parameter set. For example, the CWmax value of a specific AC in the MU EDCA parameter set may be set to be greater than the CWmax value of the same AC in a conventional parameter set. Additionally, the AIFSN value of a specific AC in the MU EDCA parameter set may be set to be greater than the AIFSN value of the same AC in a conventional parameter set. By using the MU EDCA parameter set configured as described above, STAs participating in UL-MU transmission can perform individual channel access with a lower transmission probability than conventional methods.

[0089] Figure 7 The illustration depicts a handover operation between a conventional EDCA mode and a multi-user EDCA mode according to an embodiment of the present invention. The STA according to an embodiment of the present invention can update the EDCA parameters used for channel access based on an EDCA parameter set selected from a conventional EDCA parameter set and a multi-user EDCA parameter set. The STA performs channel access based on the updated EDCA parameters. Therefore, the STA can perform a handover between conventional EDCA modes 50a and 50b, in which channel access is performed using the conventional EDCA parameter set, and MU EDCA mode 60, in which channel access is performed using the MU EDCA parameter set. In embodiments of the present invention, the handover between conventional EDCA modes 50a and 50b and MU EDCA mode 60 can indicate a mode switch for a specific access category.

[0090] refer to Figure 7A STA that has successfully performed UL-MU transmission can switch from conventional EDCA mode 50a to MU EDCA mode 60. More specifically, a STA switches from conventional EDCA mode 50a to MU EDCA mode 60 when the following conditions are met.

[0091] First condition: The STA should receive a trigger frame 410 from the AP instructing the STA to transmit its UL-MU. That is, the STA should receive a trigger frame 410 containing a user information field indicating the corresponding STA's AID. In this case, the trigger frame can be a basic trigger frame.

[0092] Second condition: In response to receiving trigger frame 410, the STA should send trigger-based PPDU 420 to the AP. In this case, the trigger-based PPDU 420 should contain QoS data frames.

[0093] Third condition: The STA should receive an immediate response 430 from the AP for the triggered PPDU 420. In this case, the immediate response may instruct the receiver to send a response to the sender within a predetermined duration within the same transmission opportunity (TXOP). M-BA can be used as an embodiment of the direct response 430, but the invention is not limited thereto.

[0094] If the above three conditions are met, the STA can switch the mode of the corresponding access category from traditional EDCA mode 50a to MU EDCA mode 60. When switching to MU EDCA mode 60, the STA updates the EDCA parameters of the corresponding access category based on the MU EDCA parameter set. More specifically, the STA updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​of all categories that successfully transmit QoS data via triggered PPDU 420 using the values ​​specified in the MU EDCA parameter set. The STA uses the updated EDCA parameters to access the channel. More specifically, the STA resets the contention window based on the updated contention window minimum and / or contention window maximum, and obtains a backoff timer within the set contention window. The STA uses the obtained backoff timer to perform the backoff process.

[0095] According to another embodiment of the invention, the first and second conditions may include the STA receiving a trigger frame 410 from the AP indicating at least one random access resource element and, in response, transmitting a trigger-based PPDU 420 via random access. Alternatively, if the trigger-based PPDU 420 transmitted by the STA does not request an immediate response, the third condition may be omitted. In this case, when the first and second conditions are met, the STA can switch from conventional EDCA mode 50a to MUEDCA mode 60 regardless of whether an immediate response 430 is received.

[0096] According to one embodiment, the STA can switch to MU EDCA mode 60 when it receives an immediate response 430 from the AP for the trigger-based PPDU 420. According to another embodiment, if the trigger-based PPDU 420 sent by the STA does not request an immediate response, the STA can switch to MU EDCA mode 60 when the transmission of the trigger-based PPDU 420 is complete.

[0097] When a STA switches its access class mode from traditional EDCA mode 50a to MU EDCA mode 60, the STA sets a MU EDCA timer (i.e., HEMUEDCATimer[AC]) for the corresponding access class. The MU EDCA timer uses parameters updated based on the MUEDCA parameter set to indicate the duration of channel access for the corresponding access class. In this case, the MU EDCA timer can be maintained and managed for each access class. Furthermore, MU EDCA timer information can be included in the MUEDCA parameter set. The MU EDCA parameter set can represent MU EDCA timer information via the MU EDCA timer subfield. The STA sets the MU EDCA timer using the value of the MU EDCA timer field of the MU EDCA parameter set most recently received from the AP to which the STA is associated.

[0098] Unless the STA successfully performs an additional UL-MU transmission, the MU EDCA timer decrements. When the MU EDCA timer reaches zero, the STA switches the mode for the corresponding access class from MU EDCA mode 60 to traditional EDCA mode 50b. By configuring the MU EDCA timer as described above, if an additional UL-MU transmission fails within a specific duration after applying the MU EDCA parameter set, the STA can revert to traditional EDCA mode 50b.

[0099] If the mode of a specific access category of the STA switches from MU EDCA mode 60 to traditional EDCA mode 50b (i.e., the MU EDCA timer for the specific access category reaches zero), the STA updates the EDCA parameters for the corresponding access category based on the traditional parameter set. According to an embodiment, the STA can update the EDCA parameters based on the traditional EDCA parameter set most recently received from the AP associated with the STA. If no traditional EDCA parameter set is received from the AP associated with the STA, the STA updates the EDCA parameters based on a predetermined default EDCA parameter set. The STA uses the updated EDCA parameters to access the channel. More specifically, the STA resets the contention window based on the updated contention window minimum and / or contention window maximum, and obtains a backoff timer within the set contention window. The STA uses the obtained backoff timer to perform the backoff procedure.

[0100] Figure 8 The illustration shows the configuration of multi-user EDCA parameter set elements according to an embodiment of the present invention. More specifically, Figure 8 (a) Illustration of MU EDCA parameter set elements, Figure 8 (b) Illustration of the abbreviation MU EDCA parameter set elements. Furthermore... Figure 8 (c) The illustration shows the elements of the “MU QoS Info” field included in the MU EDCA parameter set or abbreviation of the MU EDCA parameter set.

[0101] refer to Figure 8 (a) The MU EDCA parameter set element includes an element identifier field, namely, the "Element ID" field and the "Element ID Extension" field. Additionally, the MU EDCA parameter set element includes multiple "MU AC Parameter Record" fields, which represent the EDCA parameters for each access class. More specifically, the MU EDCA parameter set element includes the "MU AC_BE Parameter Record" field, the "MU AC_BK Parameter Record" field, the "MU AC_VI Parameter Record" field, and the "MU AC_VO Parameter Record" field. Each "MU AC Parameter Record" field can indicate the EDCA parameters for the corresponding access class, namely, the AIFSN, CWmin, and CWmax values. Furthermore, the MU EDCA parameter set element may also include MU EDCA timer information for each access class.

[0102] MUEDCA parameter set elements can be sent via probe responses and / or association responses during the initial link establishment process between the STA and AP. Additionally, MU EDCA parameter set elements can be sent via beacon frames while the AP is manipulating MU EDCA parameters in the BSS. The STA receiving the MU EDCA parameter set elements can update the EDCA parameters for each access class based on the value of the "MU AC Parameter Record" field in the MU EDCA mode.

[0103] Additionally, the MU EDCA parameter set elements include a "MU QoS Info" field. (See reference) Figure 8 (c) The “MU QoS Info” field includes a “MU EDCA Parameter Set Update Count” subfield (hereinafter referred to as the Update Count subfield). The Update Count subfield is initially set to zero and increments each time the MU EDCA parameters are changed. Therefore, the Update Count subfield indicates how many times the MU EDCA parameters have been changed.

[0104] When the MU EDCA parameter set is changed, the AP can increment the update count subfield value by 1. STAs that have already received the MU EDCA parameter set from the AP can determine whether to change the MU EDCA parameter set based on the value of the update count subfield. Meanwhile, the format of the subfields of the "MU QoS Information" field, excluding the update count subfield, can be the same as the format of the corresponding subfields of the existing "QoS Information" field.

[0105] Figure 8 (b) The diagram illustrates an abbreviated MU EDCA parameter set element according to another embodiment of the present invention. If the value of the update count subfield of the MU EDCA parameter set received via a beacon frame, etc., has not changed from the update count subfield value previously obtained by the STA, the STA may not check the following "MU AC parameter record" field. Therefore, sending the "MU AC parameter record" field for each beacon frame may be inefficient if the value of the update count subfield has not changed. Therefore, as Figure 8 As shown in (b), the MU EDCA parameter set where the “MU AC parameter record” field is omitted, i.e., the abbreviated MU EDCA parameter set, can be used. The AP can selectively send the MU EDCA parameter set or the abbreviated MU EDCA parameter set based on whether the value of the update counter subfield has been changed.

[0106] Figure 9 The illustration depicts a method for sending a multi-user EDCA parameter set according to an embodiment of the present invention. (Reference) Figure 9 The AP can send the MU EDCA parameter set via the initial link establishment frame 510. In this case, the initial link establishment frame 510 includes at least one of a probe response and an association response. Alternatively, the AP can send the MU EDCA parameter set via the periodically sent beacon frame 520.

[0107] according to Figure 9 In this embodiment, the update count subfield in the initial link establishment frame 510 and beacon frames 520a and 520b is set to 5. However, after transmitting beacon frame 520b, the MU EDCA parameter set is changed and the AP increments the value of the update count subfield by 1. Therefore, the update count subfield in beacon frames 520c, 520d, and 520e is set to 6.

[0108] According to an embodiment of the invention, if the value of the update count subfield has not changed from the previous value, the AP can send the abbreviated MU EDCA parameter set via beacon frames 520a, 520b, 520d, and 520e. The AP can send the MU EDCA parameter set via beacon frame 520c only if the value of the update count subfield has changed from the previous value. If the value of the update count subfield is identified as having changed from a previously obtained update count subfield value in the received beacon frame 520c, the STA can check the "MU AC Parameter Record" field to obtain the MU EDCA parameters.

[0109] According to another embodiment of the invention, the AP can send an abbreviated MU EDCA parameter set for each beacon frame 520a, 520b, 520c, 520d, and 520e. If a change in the value of the update count subfield is detected in the received beacon frame 520c from a previously obtained update count subfield value, the STA can send a probe request frame, etc., to request the AP to send the MU EDCA parameter set.

[0110] When switching to MU EDCA mode, the STA updates the EDCA parameters based on the MU EDCA parameter set. In this case, the STA can update the EDCA parameters based on the MU EDCA parameter set most recently received from the AP associated with the STA. If no MU EDCA parameter set is received from the AP associated with the STA, the STA can update the EDCA parameters based on the predefined default MU EDCA parameter set. If no default MU EDCA parameter set exists, the STA can update the EDCA parameters based on the traditional EDCA parameter set even in MU EDCA mode.

[0111] Furthermore, according to embodiments of the present invention, the MU EDCA parameter set can be used selectively. The AP and / or STA can enable or disable the application of the MU EDCA parameter set. Reference will be made below. Figures 10 to 14 A method for selectively using the MU EDCA parameter set according to an embodiment of the present invention is described.

[0112] Figure 10 The illustration depicts a method for disabling multi-user EDCA according to an embodiment of the present invention. According to an embodiment of the present invention, the AP can determine whether to enable MU EDCA. In this case, the AP can disable MU EDCA by not including MU EDCA parameter set elements in periodically transmitted beacon frames. Figure 10 In the embodiments, beacon frames 522a and 522b include MU EDCA parameter set elements, while beacon frames 524a and 524b do not include MU EDCA parameter set elements.

[0113] If the MU EDCA parameter set elements are not extracted from the received beacon frame 524a, the STA can switch the access class in MU EDCA mode 60 to traditional EDCA mode 50. In this case, the STA updates the EDCA parameters based on the traditional EDCA parameter set. More specifically, the STA can perform at least one of the following operations.

[0114] A-1) The STA will update the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​of all access categories operating in MU EDCA mode 60 to values ​​included in the conventional EDCA parameter set. More specifically, the STA can update the EDCA parameters of all access categories with non-zero MU EDCA timers to values ​​included in the conventional EDCA parameter set most recently received from the AP associated with the STA. If a conventional EDCA parameter set has not yet been received from the AP associated with the STA, the STA will update the EDCA parameters of all access categories with non-zero MU EDCA timers to values ​​included in a predetermined default EDCA parameter set. That is, the STA updates the EDCA parameters to values ​​included in the conventional EDCA parameter set most recently received from the AP associated with the STA, or updates them to values ​​included in a predetermined default EDCA parameter set. On the other hand, no special operation is required for access categories already operating in conventional EDCA mode 50.

[0115] (A-2) The STA sets the MU EDCA timer for all access classes operating in MU EDCA mode 60 to zero and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access classes to the values ​​contained in the traditional EDCA parameter set. The specific method for updating the STA's EDCA parameters to the values ​​contained in the traditional EDCA parameter set is described in (A-1). Because the MU EDCA timer is designed to decrement without pausing, if it is not set to zero, the MU EDCA timer can continue to decrement even after switching to traditional EDCA mode 50. If the MU EDCA timer subsequently reaches zero, unnecessary Management Information Base (MIB) updates can still be performed even though the corresponding access class has switched to traditional EDCA mode 50. Therefore, the STA sets the MU EDCA timer for all access classes to zero.

[0116] (A-3) The STA sets the MU EDCA timers for all access categories operating in MU EDCA mode 60 to zero and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access categories to values ​​included in the conventional EDCA parameter set. Additionally, the STA resets the contention window based on the updated CWmin[AC] and / or CWmax[AC] and obtains the backoff timer within the set contention window. As described above, according to an embodiment of the invention, at least one parameter in the MU EDCA parameter set can be set to a value greater than the corresponding parameter in the conventional EDCA parameter set. In this case, when channel access in conventional EDCA mode 50 is performed using the contention window and backoff timer set in MU EDCA mode 60, the STA's channel access can be restricted. Therefore, the STA resets the contention window and backoff timer for the access category, switching to conventional EDCA mode 50. According to an embodiment, the STA can initialize the contention window and backoff timer based on conventional EDCA parameters. According to another embodiment, the STA can reset the contention window and backoff timer based on the ratio between CWmin[AC] and CWmax[AC] of the conventional EDCA parameter set and CWmin[AC] and CWmax[AC] of the MU EDCA parameter set.

[0117] According to another embodiment of the present invention, the above is in Figure 8 The abbreviated MU EDCA parameter set described herein can be used. In this case, when no abbreviated MU EDCA parameter set element other than the MU EDCA parameter set element is extracted from the received beacon frame, the STA can perform any of operations A-1) to A-3). If at least one of the MU EDCA parameter set element and the abbreviated MU EDCA parameter set element is extracted from the received beacon frame, the STA does not perform the above operations because the AP allows the use of MU EDCA parameters.

[0118] Figure 11 The illustration shows the configuration of an operation mode indicator element according to an embodiment of the present invention. A non-traditional STA can change its transmit / receive parameters and notify this change by transmitting a separate element. According to an embodiment, the STA can use... Figure 11 The Operation Mode Indicator (OMI) element shown is used to change its operation mode setting.

[0119] OMI information (optionally, OMI elements and OMI control fields) can be included as an efficient (HE) variant of the HT control field in the MAC header of a frame sent by a non-traditional terminal. The terminal sending the frame containing OMI information is defined as the OMI initiator, and the terminal receiving the frame containing OMI information is defined as the OMI responder. The OMI initiator, having already sent the frame containing OMI information, can change its send / receive parameters when it receives an immediate response from the OMI responder.

[0120] refer to Figure 11 The OMI element includes a UL-MU disable subfield. The UL-MU disable subfield indicates whether the corresponding STA participates in UL-MU transmission. More specifically, when the UL-MU disable subfield is set to zero, it indicates that the STA participates in UL-MU transmission. According to an embodiment, the STA's UL-MU transmission can be based on triggered PPDU transmission. Triggered PPDU transmission can be performed based on the number of space-time streams of the STA in the resource element assigned within the STA's operating channel width. In this case, the STA's operating channel width is indicated by the channel width subfield of the OMI element, and the number of space-time streams of the STA is determined within the value indicated by the transmission NSTS (i.e., Tx NSTS) subfield of the OMI element. On the other hand, when the UL-MU disable subfield is set to 1, it indicates that the STA's UL-MU operation is suspended. In this case, the STA does not participate in UL-MU transmission until a frame containing OMI information in which the UL-MU disable subfield is set to zero is transmitted.

[0121] Figure 12 The diagram illustrates a method for controlling multi-user transmission based on operating mode indication information. Figure 12 In this embodiment, the OMI initiator sends frame 610 containing OMI information and receives an immediate response 620 from the OMI responder. In this case, the UL-MU disable subfield of the OMI information included in frame 610 indicates a pause in UL-MU operation. That is, the UL-MU disable subfield is set to 1. Here, the OMI initiator is a non-AP STA, and the OMI responder is an AP.

[0122] According to an embodiment of the present invention, the OMI responder AP believes that the OMI initiator STA, which has already sent a frame 610 containing OMI information with the UL-MU disabled subfield set to 1, will not respond to any type of trigger frame. Therefore, the AP may not schedule the OMI initiator STA for UL-MU transmission. Additionally, when the MAC protocol data unit (MPDU) addressed to the STA in the HE MU PPDU 630 sent by the AP is a MAC management protocol data unit (MMPDU) or an MPDU in which the "ACK policy" subfield of the "QoS control" subfield is set to MU ACK, the OMI initiator STA may not be able to send an immediate response 640 in UL-MU form. Therefore, when the OMI responder AP performs a DL-MU transmission to the OMI initiator STA using HE MU PPDU 630, the OMI responder AP may not aggregate the MPDU requesting an immediate response 640 in UL-MU form into the A-MPDU sent to the corresponding STA. In this case, the MPDU requesting an immediate response in the form of UL-MU 640 includes an action frame, a trigger frame, an MPDU containing the UL-MU response schedule, and an MPDU in which the "ACK policy" subfield of the "QoS control" field is set to MU ACK, etc.

[0123] Figure 13 The illustration shows a method for disabling multi-user EDCA according to another embodiment of the present invention. Except where the AP does not allow the use of the MU EDCA parameter set, the STA can immediately suspend the use of the MU EDCA parameter set at a specific point in time. The STA can suspend the use of the MU EDCA parameter set by sending a frame containing an OMI element with the UL-MU disabled subfield set to 1, as referenced above. Figure 11 As stated above.

[0124] refer to Figure 13 The OMI initiator (STA) sends a frame 710 containing OMI information with a UL-MU disabled subfield set to 1, and receives an immediate response 720 from the OMI responder. Thus, when a frame 710 containing OMI information in which the UL-MU disabled subfield indicates a suspension of UL-MU operation is sent and an immediate response 720 from the OMI responder is received in response to the frame 710 containing the OMI, the STA can switch the access category in MU EDCA mode 60 to traditional EDCA mode 50. In this case, the STA updates the EDCA parameters based on the traditional EDCA parameter set. More specifically, the STA can perform at least one of the following operations.

[0125] (B-1) The STA will update the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for all access classes operating in MU EDCA mode 60 to values ​​included in the conventional EDCA parameter set. More specifically, the STA may update the EDCA parameters for all access classes with non-zero MU EDCA timers to values ​​included in the conventional EDCA parameter set most recently received from the AP associated with the STA. If a conventional EDCA parameter set has not yet been received from the AP associated with the STA, the STA will update the EDCA parameters for all access classes with non-zero MU EDCA timers to values ​​included in a predetermined default EDCA parameter set. That is, the STA updates the EDCA parameters to values ​​included in the conventional EDCA parameter set most recently received from the AP associated with the STA, or to values ​​included in a predetermined default EDCA parameter set.

[0126] (B-2) The STA sets the MU EDCA timer for all access categories operating in MU EDCA mode 60 to zero and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access categories to the values ​​contained in the traditional EDCA parameter set. The specific method for updating the STA's EDCA parameters to the values ​​contained in the traditional EDCA parameter set is described in (B-1). Because the MU EDCA timer is designed to decrement without pausing, if it is not set to zero, the MU EDCA timer can continue to decrement even after switching to traditional EDCA mode 50. If the MU EDCA timer subsequently reaches zero, unnecessary Management Information Base (MIB) updates can still be performed even though the corresponding access category has switched to traditional EDCA mode 50. Therefore, the STA sets the MU EDCA timer for all access categories to zero.

[0127] (B-3) The STA sets the MU EDCA timers for all access categories operating in MU EDCA mode 60 to zero and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access categories to values ​​included in the conventional EDCA parameter set. Additionally, the STA resets the contention window based on the updated CWmin[AC] and / or CWmax[AC] and obtains the backoff timer within the set contention window. As described above, according to an embodiment of the invention, at least one parameter of the MU EDCA parameter set can be set to a value greater than the corresponding parameter of the conventional EDCA parameter set. In this case, when channel access in conventional EDCA mode 50 is performed using the contention window and backoff timer set in MU EDCA mode 60, the STA's channel access can be restricted. Therefore, the STA resets the contention window and backoff timer for the access category, switching to conventional EDCA mode 50. According to an embodiment, the STA can initialize the contention window and backoff timer based on conventional EDCA parameters. According to another embodiment, the STA can reset the contention window and backoff timer based on the ratio between CWmin[AC] and CWmax[AC] of the conventional EDCA parameter set and CWmin[AC] and CWmax[AC] of the MU EDCA parameter set.

[0128] Figure 14 The illustration shows a method for disabling multi-user EDCA according to another embodiment of the present invention. The STA can notify the AP that there is no more data in a specific access class to receive UL-MU scheduling. According to an embodiment, the STA can send a buffer status report via the uplink to deliver information about the size of the remaining data in the specific access class to the AP.

[0129] refer to Figure 14 The STA can indicate the size of the remaining data in the buffer for the corresponding TID, including the data currently being transmitted, through the "Queue Size" subfield of the "QoS Control" field in the MAC header of the triggered PPDUs 820a and 820b, sent in response to triggered frames 810a and 820b. Figure 14 As shown in (a), the STA can indicate the size of the remaining data in the buffer for each TID (i.e., TID 1, TID 0) via the "Queue Size" subfield of the corresponding frame. Additionally, as... Figure 14 As shown in (b), the STA can indicate the size of the remaining data in the buffer for a specific TID, for which data is not sent via the "queue size" subfield of the QoS empty frame.

[0130] The AP can indicate that all data transmissions were successful by responding to PPDUs 820a and 820b sent by the STA with PPDUs 830a and 830b. If the size of the data indicated by the "Queue Size" subfield is the same as the size of the data sent for the corresponding TID, such as... Figure 14 As shown in the embodiment, no data to be sent is retained in the buffer of the corresponding TID. In this case, both the AP and STA can recognize that the size of the remaining data in the buffer of the corresponding TID is 0. Figure 14 As in the embodiment, if the buffer sizes for both "TID 0" and "TID 1" are 0, then there is no remaining data in the "Access Category" queue. In this way, when both the AP and STA recognize that the buffer sizes for all TIDs belonging to a specific access category are 0 when the STA completes the UL transmission, the STA can switch the mode of the corresponding access category from MU EDCA mode 60 to traditional EDCA mode 50. In this case, the STA updates the EDCA parameters for the corresponding access category based on the traditional EDCA parameter set. More specifically, the STA can perform at least one of the following operations.

[0131] C-1) The STA updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access class to values ​​included in the traditional EDCA parameter set. More specifically, the STA can update the EDCA parameters for the corresponding access class to values ​​included in the traditional EDCA parameter set recently received from the AP associated with the STA. If a traditional EDCA parameter set has not yet been received from the AP associated with the STA, the STA updates the EDCA parameters for the corresponding access class to values ​​included in a predetermined default EDCA parameter set. That is, the STA updates the EDCA parameters to values ​​included in the traditional EDCA parameter set recently received from the AP associated with the STA, or updates them to values ​​included in a predetermined default EDCA parameter set.

[0132] (C-2) The STA sets the MU EDCA timer for the corresponding access class to zero and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access class to the values ​​included in the traditional EDCA parameter set. The specific method for updating the STA's EDCA parameters to the values ​​included in the traditional EDCA parameter set is described in (C-1).

[0133] (C-3) The STA sets the MU EDCA timer for the corresponding access class operating in MU EDCA mode 60 to zero, and updates the AIFSN[AC], CWmin[AC], and CWmax[AC] values ​​for the corresponding access class to the values ​​included in the traditional EDCA parameter set. Additionally, the STA resets the contention window for the corresponding access class based on the updated CWmin[AC] and / or CWmax[AC], and obtains the backoff timer within the set contention window. The specific methods by which the STA obtains the contention window and backoff timer are described in (A-3) and (B-3).

[0134] HE MU PPDU Configuration Method

[0135] Figures 15 to 17 The illustration shows a method for configuring a HE MU PPDU according to an embodiment of the present invention. Figures 15 to 17 In this embodiment, multiple STAs perform UL-MU transmission in response to the AP's trigger frame. Additionally, in response to the UL-MU transmission, they receive M-BA. In this case, the M-BA is transmitted in the form of an HE MU PPDU. Figures 15 to 17 In the embodiments, RU1, RU2, RU3, RU4, RU5 and RU6 indicate each resource unit that makes up the HE MU PPDU.

[0136] Figure 15 The illustration shows a configuration of an HE MU PPDU according to an embodiment of the present invention. In a non-traditional wireless LAN system, if a triggered PPDU request sent in the UL-MU is immediately acknowledged, the AP can send a block acknowledgment (BA) to multiple STAs in the form of an HE MU PPDU. Furthermore, the M-BA used in a non-traditional wireless LAN system can contain ACK information for multiple STAs in a single MAC frame. Therefore, group-addressed M-BAs and individually addressed M-BAs can be mixed in a single HE MU PPDU.

[0137] The HE MU PPDU can indicate the receiver AID corresponding to each resource unit on which it performs the transmission via the user information field of HE-SIG-B. In this case, the broadcast AID is inserted into the user information field corresponding to the resource unit (i.e., RU1) to which the group-addressed M-BA is assigned, and the AID of each receiver STA is inserted into the user information field corresponding to the resource units (i.e., RU2 to RU6) to which individually-addressed M-BAs are assigned. However, when multiple different group-addressed M-BAs are transmitted via a single HE MU PPDU, multiple broadcast AIDs corresponding to different resource units can be inserted into the user information field of HE-SIG-B. If the AID of the STA participating in the UL-MU transmission is not present in the HE-SIG-B of the HE MU PPDU, the corresponding STA may not be able to identify which resource unit AID among the multiple resource units corresponding to multiple broadcasts contains its ACK information.

[0138] Therefore, according to embodiments of the invention, when multiple different M-BAs are transmitted via a single HE MU PPDU, the restriction that only one or fewer group-addressed M-BAs should exist within the HEMU PPDU can be applied. Additionally, the AP should transmit the corresponding M-BA on a 20MHz channel that includes resource elements in which the UL-MU transmission participating STA, as the target of each M-BA, has already transmitted a triggered PPDU.

[0139] Figure 16 The illustration shows a configuration of an HE MU PPDU according to another embodiment of the present invention. According to the foregoing embodiment, when a group-addressed M-BA is transmitted through a specific resource element (i.e., RU1) of the HE MU PPDU, it may be impossible to transmit a group-addressed A-MPDU through another resource element. However, when executing a MU concatenation sequence defined in a non-traditional wireless LAN system, transmission efficiency can be increased if a group-addressed trigger frame is transmitted through another resource element (e.g., RU2).

[0140] Therefore, according to Figure 16In this embodiment, a separate broadcast AID can be specified for the M-BA used for group addressing. A general broadcast AID can be used for group addressing A-MPDUs other than the M-BA. In a non-traditional wireless LAN system, a STA receiving an HE MU PPDU cannot receive an A-MPDU targeting itself in multiple resource elements. Therefore, a STA needing to receive an ACK from an HE MU PPDU can receive the ACK information through the resource element (i.e., RU1) assigned to a separate broadcast AID. On the other hand, a STA not scheduled to receive an ACK from an HE MU PPDU can receive data through the resource element corresponding to its AID, or through the resource element (i.e., RU2) corresponding to the broadcast AID, which can receive group addressing via a trigger frame.

[0141] Figure 17 The illustration shows the configuration of a HE MU PPDU according to yet another embodiment of the present invention. Figure 17 In one embodiment, multiple broadcast AIDs can be inserted into the user information field of the HE-SIG-B of the HE MU PPDU. In this case, the index order of resource unit allocation can be used to classify packet-addressable M-BAs and group-addressable A-MPDUs (excluding M-BAs) within a HE MU PPDU. The resource unit allocation field of the HE-SIG-B of the HE MU PPDU indicates the partitioning and arrangement information of resource units through a predetermined index. Furthermore, the user information field of the HE-SIG-B sequentially indicates the AID value of each resource unit according to the arrangement of resource units indicated by the resource unit allocation field.

[0142] According to embodiments of the present invention, when two broadcast AIDs are represented by the user information field of the HE-SIG-B of the HE MU PPDU, group addressing targets can be implicitly specified according to the order in which the respective broadcast AIDs are represented. According to one embodiment, the first represented broadcast AID may indicate a resource element for an M-BA used for group addressing, and the next represented broadcast AID may indicate a resource for an A-MPDU used for group addressing other than the M-BA. According to another embodiment, implicit specification can be performed in reverse order. If the two broadcast AIDs are assigned to different 20MHz channels, implicit specification can be performed based on the order of the channel binding rules of the wireless LAN system.

[0143] Although the invention has been described using wireless LAN communication as an example, it is not limited thereto, and can be similarly applied to other communication systems, such as cellular communication, etc. Furthermore, while the methods, apparatus, and systems of the invention have been described in conjunction with specific embodiments, some or all of the components and operations of the invention can be implemented using a computer system with a general-purpose hardware architecture.

[0144] The embodiments described in the detailed description of the present invention can be implemented by various means. For example, embodiments of the present invention can be implemented by hardware, firmware, software, and / or combinations thereof.

[0145] In hardware implementation, the method according to embodiments of the present invention can be implemented by one or more of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, etc.

[0146] In the case of firmware or software implementation, the method according to embodiments of the present invention can be implemented by modules, processes, functions, etc., that perform the operations described above. Software code can be stored in memory and operated by a processor. The processor can be equipped with memory internally or externally, and the memory can exchange data with the processor through various publicly known means.

[0147] The description of this invention is illustrative, and those skilled in the art will understand that the invention can be readily modified into other detailed forms without changing the technical concept or essential features. Therefore, it should be understood that the embodiments described above are intended to be illustrative in various senses and not restrictive. For example, each component described as a single type can be implemented as distributed, and similarly, components described as distributed can be implemented in an associated manner.

[0148] The scope of this invention is indicated by the claims to be described below, rather than by a detailed description, and it is to be understood that the meaning and scope of the claims and all variations or modifications derived from their equivalents fall within the scope of this invention.

[0149] Industrial applicability

[0150] Various exemplary embodiments of the present invention have been described with reference to the IEEE 802.11 system; however, the present invention is not limited thereto, and the present invention can be applied to various types of mobile communication devices, mobile communication systems, etc.

Claims

1. A wireless communication terminal, the terminal comprising: Communication unit; and A processor configured to control the transmission and reception of wireless signals via the communication unit. The processor is configured as follows: The EDCA parameters used for channel access are updated based on the EDCA parameter set selected from the first enhanced distributed channel access EDCA parameter set and the second EDCA parameter set. Channel access is performed based on the updated EDCA parameters. The second EDCA parameter set is a MU EDCA parameter set used for multi-user MU EDCA operations, and includes a MU EDCA timer indicating the duration of channel access execution, and Specifically, when updating the EDCA parameters based on the MU EDCA parameter set, the MU EDCA timer included in the MU EDCA timers for all access categories is set using the updated EDCA parameters based on the MU EDCA parameter set. Send a frame containing Operation Mode Indication (OMI) information, including the first subfield. The first subfield indicates whether the terminal participates in uplink multi-user UL MU operation, and Specifically, when an immediate response is received for a frame containing the OMI information, the MUEDCA timer for all access categories is set to zero.

2. The wireless communication terminal according to claim 1, in, The frame further includes a second subfield indicating whether a data transmission operation for the UL MU is performed, and The EDCA parameters are updated based on the first subfield and the second subfield.

3. The wireless communication terminal according to claim 1, in, When the MU EDCA timer reaches zero, the processor updates the EDCA parameters based on the first EDCA parameter set recently received from the base station wireless communication terminal associated with the terminal.

4. The wireless communication terminal according to claim 1, in, The MU EDCA timer is set to the value of the MU EDCA timer subfield of the MU EDCA parameter set most recently received from the base station wireless communication terminal associated with the terminal.

5. The wireless communication terminal according to claim 1, in, The first EDCA parameter set and the second EDCA parameter set are received via at least one of a beacon frame, a probe response frame, and an association response frame sent by a base station wireless communication terminal associated with the terminal.

6. A wireless communication method for a wireless communication terminal, the method comprising: Update the EDCA parameters used for channel access based on the EDCA parameter set selected from the first enhanced distributed channel access EDCA parameter set and the second EDCA parameter set; Channel access is performed based on the updated EDCA parameters. The second EDCA parameter set is a MU EDCA parameter set used for multi-user MU EDCA operations, and includes a MU EDCA timer indicating the duration of channel access execution, and Specifically, when updating the EDCA parameters based on the MU EDCA parameter set, the MU EDCA timer included in the MU EDCA timers for all access categories is set using the EDCA parameters updated based on the MU EDCA parameter set; and Send a frame containing Operation Mode Indication (OMI) information, including the first subfield. The first subfield indicates whether the terminal participates in uplink multi-user UL MU operation, and Specifically, when an immediate response is received for a frame containing the OMI information, the MUEDCA timer for all access categories is set to zero.

7. The wireless communication method according to claim 6, in, The frame further includes a second subfield indicating whether a data transmission operation for the UL MU is performed, and The EDCA parameters are updated based on the first subfield and the second subfield.

8. The wireless communication method according to claim 6, in, When the MU EDCA timer reaches zero, the EDCA parameters are updated based on the first EDCA parameter set recently received from the base station wireless communication terminal associated with the terminal.

9. The wireless communication method according to claim 6, in, The MU EDCA timer is set to the value of the MU EDCA timer subfield of the MU EDCA parameter set most recently received from the base station wireless communication terminal associated with the terminal.

10. The wireless communication method according to claim 6, in, The first EDCA parameter set and the second EDCA parameter set are received via at least one of a beacon frame, a probe response frame, and an association response frame sent by a base station wireless communication terminal associated with the terminal.

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