WO2015037914A1 - Channel access control method and apparatus in wireless lan system - Google Patents

Abstract

Disclosed is a method and apparatus for controlling channel access for a station by an access point in a wireless LAN system. An access point according to an embodiment may determine resource allocation information for protecting a resource of a station that does not refer to traffic indication map (TIM) information. The determined resource allocation information is transmitted to a station which refers to the TIM information, and the station which refers to the TIM information does not perform channel access during a certain time interval indicated in the resource allocation information.

Description

Method and apparatus for controlling channel access in WLAN system

The following description relates to a wireless communication system, and more particularly, to a method and apparatus for controlling channel access in a WLAN system, and a station operating accordingly.

Wireless Local Area Network (WLAN) is a technology that enables wireless access to the Internet in a home, business, or specific service area using a portable terminal based on radio frequency technology. If there are too many stations (STAs) in the network in the WLAN, there is a high probability of collision between STAs during channel access. STAs that perform channel access without listening to beacon signals may contend with other STAs to which slots are allocated during the channel access process, and such competition may reduce the efficiency of the entire network. Can be.

In one embodiment, a method of controlling channel access may include determining resource allocation information for protecting a resource of a first station that does not refer to team information (TIM) information from a second station that refers to team information. ; And broadcasting the resource allocation information.

In the channel access control method according to an embodiment, the first station may request whether the resource is protected when the resource is requested to the access point.

In the channel access control method according to an embodiment, the first station may transmit a bit value indicating whether to request the protection of the resource to the access point every time the resource is requested.

In a channel access control method according to an embodiment, a bit value indicating whether to request the protection of the resource may be included in a control field or a request type field of a TWT element and transmitted.

The method of controlling channel access according to an embodiment may further include transmitting response data indicating whether the requested resource is to be protected to the first station when receiving a request for a resource from the first station. have.

In the channel access control method according to an embodiment, the determining of the resource allocation information may include determining resource allocation information for limiting channel access of the second station in a time interval for channel access of the first station. It may include.

In the channel access control method according to an embodiment, the resource allocation information may include information about a restricted access window for protecting a resource of the first station.

In the channel access control method according to an embodiment, the second station may not perform channel access in a time interval corresponding to the restricted access window.

In the channel access control method according to an embodiment, the determining of the resource allocation information comprises: receiving request data of resource protection from the first station; And when the request data is received, determining the resource allocation information that sets the time interval for which the first station requests protection as a limited access window.

In the channel access control method according to an embodiment of the present disclosure, the determining of the resource allocation information may include receiving response data indicating whether the resource protection is possible in response to the request data when receiving the request data. Transmitting to the station.

In the channel access control method according to an embodiment, the determining of the resource allocation information may include: receiving control data indicating whether to request resource protection from the first station; And determining whether the first station has requested resource protection based on the control data, and when the first station requests resource protection, setting a time interval for which the first station has requested protection as a restricted access window. Determining resource allocation information.

In the channel access control method according to an embodiment, the resource allocation information may be included in a beacon signal and transmitted to the second station.

In the channel access control method according to an embodiment, the second station is a team (TIM) station for checking downlink data buffered through a beacon signal transmitted from the access point, and the first station is the beacon signal And a non-TIM station that does not check the buffered downlink data.

According to an embodiment, a station may include: a controller configured to perform channel access to an access point and generate request data for requesting resource protection from the access point without referring to team information (TIM); And a communication unit configured to transmit the request data to the access point.

In the station according to an embodiment, the communication unit may receive response data indicating whether the resource protection is possible in response to the request data from the access point.

According to an embodiment, an access point includes a controller configured to determine resource allocation information for protecting a resource of a first station that does not refer to Team Indication Map (TIM) information from a second station that refers to the team information; And it may include a communication unit for broadcasting the resource allocation information.

In an access point according to an embodiment, the first station may request whether the resource is protected when the resource is requested to the access point.

In an access point according to an embodiment, the first station may transmit a bit value indicating whether to request the protection of the resource to the access point each time the resource is requested.

In an access point according to an embodiment, a bit value indicating whether the resource is requested to be protected may be included in a control field or a request type field of a TWT element and transmitted.

In an access point according to an embodiment, when the first station requests protection of the resource, the controller determines resource allocation information for protecting the resource that the first station has requested protection from the second station. Can be.

In an access point according to an embodiment, the controller may determine resource allocation information for limiting channel access of the second station in a time interval for channel access of the first station.

In an access point according to an embodiment, the resource allocation information may include information regarding a restricted access window for protecting a resource of the first station.

In an access point according to an embodiment, the second station may not perform channel access in a time interval corresponding to the restricted access window.

In an access point according to an embodiment, the communication unit may receive request data of resource protection from the first station, and when the controller receives the request data, a time at which the first station requests protection The resource allocation information for setting a section as a limited access window may be determined.

In an access point according to an embodiment, when receiving a request for a resource from the first station, the communication unit may transmit response data indicating whether the requested resource is to be protected to the first station.

According to another exemplary embodiment, an access point includes a communication unit configured to receive request data for resource protection from a station that does not refer to traffic information (TIM) information; And a controller configured to generate resource allocation information for protecting the resource requested by the station with a restricted access window when receiving the request data, and the communication unit may broadcast the resource allocation information.

1 is a diagram illustrating a wireless LAN environment including an access point and a plurality of stations to which an embodiment of the present invention can be applied.

2 is a diagram illustrating a field used to indicate that a resource is allocated for a non-TIM STA according to an embodiment of the present invention.

3 is a diagram illustrating a configuration of an access point according to an embodiment of the present invention.

4 is a diagram illustrating a configuration of a station according to an embodiment of the present invention.

5 is a diagram illustrating a format of a control field of a TWT element according to an embodiment of the present invention.

6 is a flowchart illustrating an operation of a channel access control method according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment or may be replaced with corresponding components or features of another embodiment.

Specific terms used in the following description are provided to help the understanding of the present invention, and the use of such specific terms may be changed to other forms without departing from the technical spirit of the present invention.

In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802 system, 3GPP system, 3GPP LTE and LTE-A (LTE-Advanced) system and 3GPP2 system. That is, steps or parts which are not described to clearly reveal the technical spirit of the present invention among the embodiments of the present invention may be supported by the above documents. In addition, all terms disclosed in the present document can be described by the above standard document.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various radio access systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). For clarity, the following description focuses on the IEEE 802.11 system, but the technical spirit of the present invention is not limited thereto.

1 is a diagram illustrating a wireless LAN environment including an access point and a plurality of stations to which an embodiment of the present invention can be applied.

A WLAN environment includes a plurality of components, and communication may be performed by interaction of these components. The basic building block in a WLAN system is called a basic service set (BSS), and the basic service set may be configured with an access point (AP) 110 and one or more stations (STAs, STAs). have.

An AP is a functional entity that provides access to a distribution system via a wireless medium for an STA associated with that AP. In an infrastructure BSS including an AP, communication between STAs is performed via an AP. However, when a direct link is established, direct communication between STAs is possible. The AP may also be called a central controller, a base station (BS), a node-B, a base transceiver system (BTS), a site controller, or a management STA.

A STA is any functional medium that includes a medium access control (MAC) conforming to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard and a physical layer interface to a wireless medium. The STA may include a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit ( Mobile Subscriber Unit) or simply another name such as User.

In the WLAN, a power saving mode (PSM) is defined to reduce power consumption of STAs. The AP may periodically transmit a beacon signal and inform the station of the presence or absence of a buffered frame through the TIM (Traffic Indication Map) field of the beacon signal. STA1, STA2, STA3, STA4, STA5, STA6, STA7, STA8, and STA9 121 to 143 are represented as STAs and will be described below.

The STA in the sleep mode may periodically wake up to receive TIM information of the beacon signal transmitted from the AP 110. If a bit value corresponding to a specific STA in the TIM information indicates 0, the STA may sleep again. If the bit value of the corresponding STA indicates 1 in the TIM information, the corresponding STA should stay awake until the last frame scheduled in the current beacon period is delivered. The STA may check whether the frame is the last frame by checking the MORE DATA field of the frame header transmitted by the AP 110. For example, when the MORE DATA field indicates 0, the STA may determine that the received frame is the last frame scheduled.

The power consumed by an STA in PSM mode is determined not only by the traffic to be transmitted to the STA, but also by the amount of traffic of another STA. This is because an interruption may occur due to an attempt to transmit data between the AP 110 and another STA in data transmission between the AP 110 and the STA. If an interruption occurs, the time until the STA receives all the buffered frames is long, which increases power consumption of the STA. As the number of STAs communicating with the AP 110 increases, the power consumption may increase more.

In order to minimize the occurrence of such interruption, the AP 110 may reduce the number of STAs accessing the channel at the same time by differently allocating time for accessing the channel for each STA. The AP 110 divides the time interval between the transmission time of the beacon signal or a smaller time interval into slots and assigns the slots to the STA in order to designate a time interval in which a specific STA can access the channel. can do. As such, allocating a slot to the STA to control channel access of the STA is referred to as slot-based channel access. The STA may perform channel access in the time interval of the allocated slot.

The AP 110 may allocate a slot to each of the STAs or a group of STAs, and allocate a restricted access window (RAW) or a periodic limited access window (Periodic RAW, PRAW) including the slot. . The PRAW can be used to protect periodically allocated resources in RAW.

The general STA may inform the AP 110 of its existence through a management operation such as an association process or a negotiation process, and set a preference for downlink transmission. I can tell you. For example, the indication and confirmation of such information may be performed through a coupling request / response process or a probe request / response process between the STA and the AP 110.

The STA's preference for downlink transmission recognizes whether there is downlink data with reference to a TIM (Traffic Indication Map), and thus receives downlink data without referring to the TIM. It may include one of the ways. One purpose of the AP 110 to provide the TIM information to the STA is to increase the efficiency of resource usage by allowing the STA to access the channel only at the time resource indicated by the TIM information.

The STA may check whether it should or does not need to receive data transmitted from the AP 110 with reference to the TIM information. Slots allocated for each STA can be known through the position of each STA in the TIM bitmap included in the beacon signal. The STA periodically receives a beacon signal transmitted from the AP 110, interprets the TIM information included in the beacon signal, and determines that there is no data to be transmitted to the STA. If it is confirmed that the data can be received without entering the sleep state. As such, an STA that receives a beacon signal and checks the existence of data to be transmitted to itself by referring to TIM information included in the beacon signal is referred to as a TIM (Traffic Indication Map) STA.

The TIM STA may check the TIM information, calculate its location, and perform channel access from the start of the allocated slot. Slots may be allocated to the entire STAs belonging to the TIM information, or TIM STAs may be divided into several groups, and slots may be allocated to each group. Since the size and channel of data to be transmitted to the TIM STA may be different, the time required for transmitting data to the TIM STA may vary for each TIM STA, and the number of slots required for each TIM STA may also vary.

Unlike the TIM STA, a STA operating without checking TIM information included in the beacon signal may be referred to as a non-TIM STA. The non-TIM STA may operate without being instructed in the TIM information. Instead of receiving the beacon signal, the non-TIM STA wakes up at any time and transmits a PS-Poll (Power Save-Poll) frame to the AP 110, thereby buffering data to be received. You can check whether or not exists. In addition, the non-TIM STA may notify the AP 110 that the service period for receiving data from the AP 110 has started by waking up at any time and transmitting a trigger frame to the AP 110. have. In addition, the non-TIM STA may wake up at any time and transmit uplink data to the AP 110. As such, when the non-TIM STA wakes up at any time and transmits a PS-Poll frame, a trigger frame, or an uplink data frame, a target beacon transmission time (TBTT) in which the AP 110 transmits a beacon signal And may overlap with RAW allocated for another STA. A non-TIM STA includes a Target Wake Time (TWT) STA and an unscheduled active polling STA (TWT), and the TWT STA includes an NDP paging STA as a scheduled active polling STA.

The AP 110 may protect resources required by the non-TIM STA from TIM STAs. For example, the AP 110 may protect resources required by the TWT STA, the NDP paging STA, and the unscheduled active polling STA from the TIM STA. The AP 110 reduces the energy consumption of the STA by reducing the probability of collision due to channel access between the STAs.

2 is a diagram illustrating a field used to indicate that a resource is allocated for a non-TIM STA according to an embodiment of the present invention.

Specifically, FIG. 2 illustrates an indication bit (non-TIM) with respect to the RPS IE 230 and the RPS IE 230 included in the restricted access window parameter set information element included in the RAW frame 220. FIG. 1 illustrates an example of protecting resources for a TWT STA or a non-TIM STA using a RAW indication. For example, the RPS IE may include RAW group information, RAW start time information, RAW duration information, slot information, and the like as RAW related information.

If the indication bit is set to 1, unnecessary information may be deleted in the RPS IE. For example, the RAW Slot Definition field, the Options field, or the RAW Group field may be deleted in the RPS IE. The field that can be deleted is not limited. If the indication bit is set to 0, all related fields can be used without the field to be deleted.

According to an embodiment, when the indication bit is set to 1 and the RAW Group field is deleted, STAs other than the TWT STA or non-TIM STA may not access the channel configured for CH Indication during RAW Duration from the RAW Start Time. . The TWT STA checks the RPS IE 210 and may operate in the assigned TWT if the TWT assigned to it is within the RAW Duration from the RAW Start Time. The non-TIM STA can access the channel in any case.

According to another embodiment, when the indication bit is set to 1 and the RAW Group field is not deleted, the STA does not perform channel access in the time interval defined in the RPS IE unless it belongs to the RAW Group defined in the RPS IE. .

A method of extending the use of the indication bit for an unscheduled active polling STA is described. Since an unscheduled active polling STA can operate by informing the AP that it is a non-TIM STA from the association stage and then receiving permission from the AP for non-TIM support, the AP can identify non-TIM STAs as an association identifier (AID). Can be managed separately by grouping. The AP may pre-schedule the RAW for the unscheduled active polling STA in advance, and inform the STA of the time of the RAW when the unscheduled active polling STA wakes up and successfully accesses the channel to perform subsequent data transmission.

3 is a diagram illustrating a configuration of an access point (AP) according to an embodiment of the present invention.

The AP 310 may transmit a beacon signal to the STAs. The AP 310 may periodically broadcast a beacon signal, and the beacon signal may include information about a BSS managed by the AP 310. The STA may wait for reception of the beacon signal and may obtain information about the network from the beacon signal. Alternatively, the STA may actively broadcast a probe request frame and request network information from the AP 310 that receives the probe request frame. The AP 310 receiving the probe request frame may include network information in a probe response frame and transmit the network information to the corresponding STA.

The beacon signal may include TIM information. The TIM information may include information indicating to which STA the AP 310 transmits data. Among the STAs, the STA that determines whether to be awake or operate in the sleep mode by determining whether data is transmitted to itself based on the TIM information included in the beacon signal is called a TIM STA 350. In contrast, an STA that does not refer to TIM information included in the beacon signal is referred to as a non-TIM STA 340. The TIM STA 350 may check the buffered downlink data through the beacon signal transmitted from the AP 310, and the non-TIM STA 340 may not check the beacon signal and the buffered downlink data. .

The non-TIM STA 340 requests the AP 310 to allocate a slot for performing channel access and performs a channel active in the corresponding slot. It may include an unscheduled active polling STA that performs access, or a station that performs power saving through Null Data Packet Paging (NDP) configuration.

The AP 310 may protect resources for the non-TIM STA 340 from the TIM STA 350. For example, the AP 310 may protect resources for the non-TIM STA 340 using RAW. The AP 310 may set a resource to be protected for the non-TIM STA 340 as RAW, and may include information on the corresponding RAW in the beacon signal and transmit the same. Upon receiving the beacon signal, the TIM STA 350 identifies the time interval protected by the RAW based on the RAW information included in the beacon signal, and does not perform channel access in the corresponding time interval, thereby making the non-TIM STA 340 available. And collision between the TIM STA 350 may be prevented.

The AP 310 may transmit information including RAW information for the non-TIM STA 340 in the RPS IE of the beacon signal. The RAW allocated to protect the resources of the non-TIM STA 340 is referred to as non-TIM RAW. The RPS IE of the beacon signal includes non-TIM RAW allocation information, and the TIM STA 350 that receives the beacon signal is assigned to non-TIM RAW in a time interval allocated to non-TIM RAW according to the non-TIM RAW allocation information included in the RPS IE. Do not perform channel access. For example, the TIM STA 350 may set the entire time interval of the non-TIM RAW as a network allocation vector (NAV), and set the channel to be busy by performing virtual CS (carrier sense). In this manner, the TIM STA 350 does not contend with other STAs for channel access, thereby reducing power consumption of the STA.

Referring to FIG. 3, the AP 310 may include a control unit 320 and a communication unit 330.

The AP 310 establishes a setup procedure with the non-TIM STA 340 to protect resources for the non-TIM STA 340 (or the first station) from the TIM STA 350 (or the second station). Can be done. The controller 320 may control a setting procedure with the non-TIM STA 340, and the communication unit 330 may perform communication with the non-TIM STA 340. The communication unit 330 may receive the request data of resource protection from the non-TIM STA 340, and when receiving the request data, the control unit 320 of the non-TIM STA 340 does not refer to the TIM information. Resource allocation information for protecting a resource from the TIM STA 350 referring to the TIM information may be generated. The communicator 330 may broadcast the determined resource allocation information. Resource allocation information may be included in the beacon signal and transmitted.

The controller 320 may determine resource allocation information for limiting channel access of the TIM STA 350 in a time interval for channel access of the non-TIM STA 340. For example, the resource allocation information may include information about RAW for protecting resources of the non-TIM STA 340. The TIM STA 350 may receive a beacon signal and obtain information of RAW allocated for the non-TIM STA 340 by referring to resource allocation information included in the beacon signal. The TIM STA 350 may not perform channel access in a time interval corresponding to the RAW allocated for the non-TIM STA 340.

In order to generate resource allocation information for protecting resources of the non-TIM STA 340, the AP 310 first performs a setting procedure with the non-TIM STA 340 to determine whether to protect the resource or a resource to be protected. You can decide.

The following describes a configuration procedure between the AP 310 and the non-TIM STA 340 TWT STA or unscheduled active polling STA, but the scope of the present invention should not be construed as being limited thereto.

<Setting Procedure between AP 310 and TWT STA> According to an embodiment

According to an embodiment, a configuration procedure between the AP 310 and the TWT STA may be performed based on the configuration of a capability field of an 802.11 management frame. First, in order for the AP 310 to perform protection through RAW, the dot11RAWOptionActivated field should be set to 1.

The capability field may be divided into two fields according to whether a resource to be protected is a resource for a TWT STA that is an STA that supports target wake time (TWT) or an unscheduled active polling STA that does not support TWT. When the resource to be protected is a resource for the TWT STA, as described above, when the TWT support field is set to 1, the controller 320 may set the TWT protection support field to 1 to support resource protection for the TWT. On the other hand, when the resource to be protected, such as the latter is a resource for the unscheduled active polling STA, when the non-TIM support field is set to 1, the control unit 320 selects a resource for channel access of the unscheduled active polling STA TIM STA ( 350, the non-TIM protection support field may be set to 1 to support a protection function.

Setting of a capability field performed by the TWT STA may be similar to that performed by the AP 310. In order to protect resources for TWT, the TWT STA may set the TWT Protection Support field to 1 when the TWT support field is set to 1. If an unscheduled active polling STA attempts to request the AP 310 for protection of resources to reduce conflicts in channel access, the unscheduled active polling STA has the non-TIM support field set to 1 and the TWT Support field set to 0. In this case, set the non-TIM Protection Support field to 1.

In either case, the TWT STA that can request resource protection may request resource protection from the AP 310 that can support resource protection. The TWT STA may request resource protection from the AP 310 by transmitting request data of resource protection. The controller 320 may set the resource requested by the TWT STA to RAW to protect the resource. The request data of resource protection may include a capability field, and a bit value of the capability field may indicate whether the TWT STA requests resource protection. For example, the TWT STA may include a TWT Protection Support capability field or a Non-TIM Protection Support capability field of a capability element included in an association request frame or a reassociation request frame. By setting it to be able to inform the AP 310 to request resource protection.

When the control unit 320 receives the resource protection request data from the non-TIM STA 340, the controller 320 may determine resource allocation information in which the resource of the time interval for which the non-TIM STA 340 has requested protection is set to RAW. . When the communication unit 330 receives the resource protection request data from the non-TIM STA 340, the communication unit 330 may include response data indicating whether protection of the resource requested by the non-TIM STA 340 is possible in response to the request data. May transmit to the TIM STA 340.

For example, when the communication unit 330 receives a frame in which the TWT Protection Support capability field is set to 1 from the TWT STA, the controller 320 selects a TWT service period (SP) of the TWT STA that transmitted the frame. By setting to RAW, the resource for the TWT STA can be controlled to be protected. The controller 320 may protect all TWT service intervals of the TWT STA through RAW.

As another example, when the communication unit 330 receives a frame from the TWT STA in which the Non-TIM Protection Support capability field is set to 1, the value of the Pill type subfield of the Frame Control field sent by the TWT STA at any time is set to 3. When the beacon signal including the RPS IE, which indicates the wakeup time of the TWT STA in the response acknowledgment (ACK) frame for the configured PS-POLL frame, can inform the protection through RAW, It can be set to indicate a time point after the TBTT. By doing so, channel access of the TIM STA 350 in the BSS is not allowed at least during the Transmission Opportunity (TxOP) after the duration value.

In addition, if both fields are set to one (for example, RAW Protection capability), and this bit of the AP 310 is set to 1, the resources of both the TWT and the non-TIM STA 340 support protection through RAW. If this bit of the non-TIM STA 340 is set to 1, RAW protection is requested according to whether the STA supports non-TIM / TWT.

The TWT STA may identify whether the AP 310 supports RAW protection through a beacon signal or probe response frame of the AP 310, and the TWT STA combines the above identification result with the AP 310 ( It may be used to select an AP 310 to associate in performing an association procedure. In addition, the AP 310 does not need to negotiate the protection of resources whenever the TWT STA establishes the TWT.

<Setting Procedure Between AP 310 and TWT STA According to Another Embodiment>

According to another embodiment, the TWT STA requests the protection of the resource once through the capability field of the IEEE 802.11 management frame, and this does not continue, but the TWT STA may inform whether the resource is protected whenever the resource is requested. The TWT STA may inform the AP 310 of a resource protection request and resource protection per TWT. The AP 310 may determine that the RAW capability is set implicitly.

When the TWT STA requests a resource for TWT from the AP 310, the TWT STA may request whether the resource is protected. The TWT STA may transmit a bit value indicating whether to request the protection of the corresponding resource to the AP 310 whenever the resource is requested. The AP 310 may include a bit value indicating whether the resource requested by the TWT STA is to be protected in the TWT response data (or response frame) and transmit it to the TWT STA. In other words, when the AP 310 receives a request for resources from the TWT STA, the communication unit 330 may transmit response data indicating whether the resource requested by the TWT STA is protected. When the AP 310 determines to protect the resource requested by the TWT STA, resource allocation information for protecting the resource requested by the TWT STA from the TIM STA may be determined.

The AP 310 needs to perform a TWT negotiation with the TWT STA according to the nature of traffic such as periodicity, latency, and service period, and whether or not to request protection of resources may vary for each TWT negotiation. . In addition, whether the AP 310 can perform protection for the new TWT may also vary. When the TWT STA requires resource protection, the AP 310 also protects the resources of the TWT STA in consideration of the situation, thereby enabling more flexible scheduling and reflecting the TWT configuration value desired by the TWT STA. It becomes possible.

To this end, control data indicating whether resource protection is requested may be used. The communication unit 330 may receive control data indicating whether to request resource protection from the TWT STA. The controller 320 may determine whether the TWT STA requests resource protection based on the received control data. If the TWT STA requests resource protection, and the control unit 320 determines to protect the resources of the time interval for which the TWT STA requests protection, the control unit 32 sets the resources of the time interval to a restricted access window for protection. Resource allocation information can be determined. When receiving control data indicating whether a resource is requested to be protected from the TWT STA, the communication unit 330 may request that the TWT response data or the resource requested by the TWT STA indicate that the resource requested by the TWT STA is to be protected by RAW. TWT response data indicating this may not protect may be transmitted to the corresponding TWT STA.

For example, when the TWT STA makes a TWT request to the AP 310, one bit constituting a control field of the TWT element illustrated in FIG. 5 may be defined as a RAW Protection bit. FIG. 5 is a diagram illustrating a format of a control field of a TWT element, and one bit of reserved bits of the control field may be defined as a RAW protection bit. If the corresponding bit is set to 1, the controller 320 may determine that the TWT resource requested by the TWT STA has requested the protection through RAW. On the contrary, when the corresponding bit is set to 0, the controller 320 may determine that the TWT resource requested by the TWT STA does not request protection through RAW. The communication unit 330 may define a bit value indicating whether the resource requested by the TWT STA is protected in the TWT control field of the TWT element, and transmit TWT response data including the corresponding TWT control field to the TWT STA.

As another example, when the TWT STA makes a TWT request to the AP 310, one bit constituting a request type field of a TWT element may be defined as a RAW Protection bit. If the corresponding bit is set to 1, the controller 320 may determine that the TWT resource requested by the TWT STA has requested the protection through RAW. On the contrary, when the RAW Protection bit is set to 0, the controller 320 may determine that the TWT resource requested by the TWT STA does not request a separate RAW protection. The communication unit 330 may define a bit value indicating whether the resource requested by the TWT STA is to be protected in the TWT request field of the TWT element and transmit TWT response data including the corresponding TWT request field to the TWT STA.

The TWT STA requesting the resource for the TWT may set the RAW protection bit of the TWT element to 1 to request the AP 310 to protect the resource requested by the AP 310. When the AP 310 receives a TWT element having the RAW Protection bit set to 1 from the TWT STA, the controller 320 determines whether to protect the resource requested by the TWT STA, and the communication unit 330 determines the resource requested by the TWT STA. TWT response data (or response frame) in which a bit value indicating whether or not to be protected is defined may be transmitted to the corresponding TWT STA. If the corresponding bit value defined in the TWT response data indicates 1, the TWT STA indicates that the resource requested through the TWT element is to be protected (guaranteed to protect). If the corresponding bit value indicates 0, the resource requested by the TWT STA is not protected. May not protect. When the control unit 320 determines that the TWT STA protects the resource requested, the control unit 320 protects the resource requested by the TWT STA (for example, a time interval from the TWT time point to a specific time point) in RAW so that the TIM STA is protected. You can restrict access to those resources. The information about the RAW may be included in the resource allocation information and broadcasted.

The TWT STA requesting the resource for the TWT may set the RAW protection bit of the TWT element to 0 to inform the AP 310 that the resource requested by the TWT STA does not need to be protected. When the AP 310 receives a TWT element from the TWT STA, the AP 310 may transmit TWT response data (or a response frame) indicating whether a resource requested by the TWT STA is protected by RAW, to the TWT STA. . The response data may include a bit value indicating whether the resource requested by the TWT STA is to be protected. If the corresponding bit value indicates 1, the response data indicates that the resource requested by the TWT STA through the TWT element is to be protected (guaranteed to protect). When the corresponding bit value indicates 0, it may represent that a resource requested by the TWT STA may not be protected.

When the TWT STA requesting the TWT resource sets the above RAW Protection bit, the AP 310 may view the case where the above RAW Protection bit is set differently. If the non-TIM STA 340 sets the RAW Protection bit to 1, in addition to the TWT STA requesting the RAW protection from the AP 310, if the TWT parameter requested from the AP 310 is satisfied, the RAW is still satisfied. If protection cannot be performed, the TWT is requested to set the priority of protection of the TWT parameters. When the TWT STA sets the RAW Protection bit to 0, the TWT STA requests the TWT to be set by giving the TWT parameter priority to the RAW Protection.

<Setting Procedure Between AP 310 and TWT STA> According to Another Embodiment

According to another embodiment, the AP 310 capable of performing RAW protection may inform the TWT STA whether resource protection is available by setting a capability field, and the TWT STA requesting RAW protection may request resource protection. May inform the AP 310. The TWT STA may use the value of the capability field to select the AP 310 to associate with. After combining with the AP 310, the TWT STA that sets the RAW protection capability field to 1 basically requests TWT protection every time the TWT is set, and if the requested TWT is not assigned by the AP 310, the TWT protection and Among the TWT parameters, you can give priority to protection. The TWT STA having the RAW protection capability field set to 0 may operate in the same manner as the existing TWT configuration without considering the TWT protection when setting the TWT. Therefore, the negotiation of setting up the RAW protection after the first time may be performed when both the AP 310 and the TWT STA have the capability field set to '1'.

<Setting procedure between the AP 310 and the unscheduled active polling STA according to an embodiment>

The RAW protection as described above may be applied to a time interval allocated by the AP 310 for channel access of an unscheduled active polling STA as well as a TWT STA. The unscheduled active polling STA may request a time duration until a time for rescheduling its awake / doze cycle while transmitting a PS-POLL frame to the AP 310. For example, the requested time interval may be a time interval up to TBTT of a beacon signal for obtaining necessary information, or a time interval up to a service interval for exchanging data. The unscheduled active polling STA that receives the response frame including the time interval may be in the doze state without performing the channel access during the corresponding time interval, and then wake up after the time interval to perform the channel access. have.

The controller 320 may check the request of the above unscheduled active polling STA based on the value of the Poll type subfield of the Frame Control field of the PS-POLL frame. unscheduled active polling The STA may request the rescheduling of an awake / dose cycle by transmitting a PS-POLL frame having the poll type set to 3, and at the same time, request time interval information up to a service interval to be scheduled as a response frame. When an unscheduled active polling STA having a Non TIM Support field set to 1 requests a PS-POLL frame having a poll type value of 3, the controller 320 may perform RAW protection to protect a corresponding service interval through RAW. . To this end, the controller 320 may adjust the start time of the service interval to be after TBTT which is a time point at which the beacon signal is sent. Here, the beacon signal may include an RPS IE signaling a RAW including a corresponding service interval. If such adjustment is impossible, the control unit 320 may inform the start time of the service section to the time point in the RAW that is already informed by the RPS IE. In this case, for example, an unscheduled active polling STA may compete with another TWT STA, but the controller 320 may reschedule a time when the competition is expected to be small.

In addition, when the AP 310 fails to perform RAW protection for the delayed resource allocation of the AP 310 to the unscheduled active polling STA, the AP 310 may inform the unscheduled active polling STA. For example, the controller 320 may inform the unscheduled active polling STA whether to perform RAW protection through one of the reserved bits of the NDP ACK frame or the reserved bits of the NDP modified ACK frame. The controller 320 may indicate that RAW protection is performed by setting the corresponding bit to 1, and may indicate that RAW protection is not performed by setting the corresponding bit to 0. FIG.

4 is a diagram illustrating a configuration of a station STA according to an embodiment of the present invention.

The STA 410 of FIG. 4 may be a non-TIM STA that performs channel access to the AP 440 without referring to team (Traffic Indication MAP 440 and TIM) information. Referring to FIG. 4, the STA 410 may include a controller 420 and a communication unit 430.

The controller 420 may generate request data for requesting resource protection from the AP 440. According to an embodiment, the request data may include a capability field of an 802.11 management frame, and the controller 420 may indicate whether to request resource protection from the AP 440 through a bit value of the corresponding capability field. The communication unit 430 may transmit the generated request data to the AP 440. The communication unit 430 may receive response data indicating whether resource protection is possible in response to the request data from the AP 440. When the STA 410 requests resource and resource protection together, the AP 440 may generate resource allocation information that sets the requested resource to RAW and broadcast the generated resource allocation information. The resource allocation information generated by the AP 440 may be included in the beacon signal transmitted by the AP 440 and broadcasted. The TIM STA receiving the corresponding resource allocation information may be set in the RAW period set by the AP 440. Does not perform channel access.

According to another embodiment, the STA 410 is a TWT STA, and the STA 410 may request the AP 440 whether to protect the resource whenever the AP 440 requests a resource for the TWT. When requesting a resource from the access point, the controller 420 may generate request data including a bit value indicating whether to request a protection for the corresponding resource. A bit value indicating whether to request the protection of a resource for the TWT may be included in a control field or a request type field of the TWT element and transmitted. The communication unit 430 may receive response data indicating whether the resource requested by the STA 410 is protected from the AP 440. The controller 420 may identify whether the resource requested by the AP is protected based on the response data received from the AP 440.

The STA 410 of FIG. 4 corresponds to the non-TIM STA 340 of FIG. 3, and a description of the STA 410 not described herein may refer to related content of FIG. 3.

6 is a flowchart illustrating an operation of a channel access control method according to an embodiment of the present invention.

In step 610, the AP may determine resource allocation information for protecting resources of the non-TIM STA from the TIM STA. The AP may perform a configuration procedure with the non-TIM STA to protect resources for the non-TIM STA from the TIM STA. The AP may determine whether to protect a resource or a resource to be protected through a configuration procedure between non-TIM STAs. For more information on the configuration procedure between the AP and the non-TIM STA, refer to the description of FIG. 3.

The AP may determine resource allocation information for limiting channel access of the TIM STA in a time interval for channel access of the non-TIM STA. For example, the resource allocation information may include information about RAW for protecting the resources of the non-TIM STA. The AP may receive request data for resource protection from the non-TIM STA, and when receiving the request data, the AP may protect a resource of the non-TIM STA that does not refer to the TIM information from the TIM STA that refers to the TIM information. Resource allocation information can be generated.

In step 620, the AP may broadcast the resource allocation information determined in step 610. Resource allocation information may be included in the beacon signal and transmitted. The TIM STA may receive a beacon signal from the AP and obtain information of RAW allocated for the non-TIM STA by referring to resource allocation information included in the beacon signal. Since the TIM STA does not perform channel access in a time interval corresponding to RAW allocated for the non-TIM STA, unnecessary power consumption may be reduced.

The embodiments described above may be implemented as hardware components, software components, and / or combinations of hardware components and software components. For example, the devices, methods, and components described in the embodiments may include, for example, processors, controllers, arithmetic logic units (ALUs), digital signal processors, microcomputers, field programmable gates (FPGAs). It may be implemented using one or more general purpose or special purpose computers, such as an array, a programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to the execution of the software. For convenience of explanation, one processing device may be described as being used, but one of ordinary skill in the art will appreciate that the processing device includes a plurality of processing elements and / or a plurality of types of processing elements. It can be seen that it may include. For example, the processing device may include a plurality of processors or one processor and one controller. In addition, other processing configurations are possible, such as parallel processors.

The software may include a computer program, code, instructions, or a combination of one or more of the above, and configure the processing device to operate as desired, or process it independently or collectively. You can command the device. Software and / or data may be any type of machine, component, physical device, virtual equipment, computer storage medium or device in order to be interpreted by or to provide instructions or data to the processing device. Or may be permanently or temporarily embodied in a signal wave to be transmitted. The software may be distributed over networked computer systems so that they may be stored or executed in a distributed manner. Software and data may be stored on one or more computer readable recording media.

The method according to the embodiment may be embodied in the form of program instructions that can be executed by various computer means and recorded in a computer readable medium. Computer-readable media may include, alone or in combination with the program instructions, data files, data structures, and the like. The program instructions recorded on the computer readable medium may be those specially designed and configured for the exemplary embodiments, or may be known and available to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

Although the embodiments have been described with reference to the accompanying drawings as described above, various modifications and variations are possible to those skilled in the art from the above description. For example, the described techniques may be performed in a different order than the described method, and / or components of the described systems, structures, devices, circuits, etc. may be combined or combined in a different form than the described method, or other components. Or even if replaced or substituted by equivalents, an appropriate result can be achieved. Therefore, other implementations, other embodiments, and equivalents to the claims are within the scope of the claims that follow.

Claims (33)

1. A channel access control method performed by an access point in a wireless LAN system,

   Determining resource allocation information for protecting a resource of a first station that does not refer to Traffic Indication Map (TIM) information from a second station that refers to the team information; And

   Broadcasting the resource allocation information

   Channel access control method comprising a.
2. The method of claim 1,

   The first station,

   When requesting a resource from the access point, requesting whether the resource is protected.
3. The method of claim 2,

   The first station,

   And transmitting a bit value indicating whether to request the protection of the resource to the access point each time the resource is requested.
4. The method of claim 3,

   And a bit value indicating whether to request the protection of the resource is included in a control field or a request type field of a TWT element and transmitted.
5. The method of claim 2,

   The first station is a target wake time (TWT) station,

   And the resource is a resource related to a TWT.
6. The method of claim 1,

   When receiving a request for a resource from the first station, sending response data indicating whether the requested resource is to be protected to the first station;

   Channel access control method further comprising.
7. The method of claim 1,

   The determining of the resource allocation information,

   Determining resource allocation information for limiting channel access of the second station in a time interval for channel access of the first station;

   Channel access control method comprising a.
8. The method of claim 1,

   The resource allocation information,

   And information about a restricted access window (RAW) for protecting a resource of the first station.
9. The method of claim 8,

   The second station,

   And no channel access is performed in a time interval corresponding to the restricted access window.
10. The method of claim 1,

    The access point is,

    And protecting the resource requested by the first station by setting it to RAW.
11. The method of claim 1,

    The determining of the resource allocation information,

    Receiving request data of resource protection from the first station; And

    When the request data is received, determining the resource allocation information for setting the time interval for which the first station requests protection as a limited access window.

    Channel access control method comprising a.
12. The method of claim 11,

    The request data of resource protection includes a capability field of an 802.11 management frame,

    And a bit value of the capability field indicates whether to request the resource protection.
13. The method of claim 1,

    The determining of the resource allocation information,

    Receiving control data indicating whether to request resource protection from the first station; And

    Determining whether the first station has requested resource protection based on the control data, and when the first station requests resource protection, setting the time interval for which the first station has requested protection as a limited access window; Determining Allocation Information

    Channel access control method comprising a.
14. The method of claim 1,

    The resource allocation information,

    And a beacon signal is transmitted to the second station.
15. The method of claim 1,

    The second station is a team (TIM) station for checking buffered downlink data via a beacon signal transmitted from the access point,

    And the first station is a non-TIM station that does not check the beacon signal and the buffered downlink data.
16. The method of claim 1,

    The first station,

    A scheduled active polling STA for requesting the access point to allocate a slot for performing channel access and performing channel access in the slot, and an unscheduled active polling for performing channel access without allocating the slot. A station (unscheduled active polling STA), and the channel access control method, characterized in that any one of the station that performs power saving through the setting of Null Data Packet Paging (NDP).
17. In a station performing channel access to an access point without referring to traffic information (TIM) information,

    A controller configured to generate request data for requesting resource protection from the access point; And

    Communication unit for transmitting the request data to the access point

    Station comprising a.
18. The method of claim 17,

    The control unit,

    When requesting a resource from the access point, the station, characterized in that for generating the request data including a bit value indicating whether the protection request for the resource.
19. The method of claim 18,

    The resource is a resource related to the TWT,

    And a bit value indicating whether a protection request relating to the resource is included in a control field or a request type field of a TWT element.
20. The method of claim 17,

    The communication unit,

    And receiving response data indicating whether a requested resource is protected from the access point in response to the request data.
21. The method of claim 18,

    The request data includes a capability field of an 802.11 management frame,

    And a bit value of the capability field indicates whether to request the resource protection.
22. A control unit for determining resource allocation information for protecting a resource of a first station that does not refer to team information (TIM) information from a second station that refers to the team information; And

    A communication unit for broadcasting the resource allocation information

    Access point comprising a.
23. The method of claim 22,

    The first station,

    When requesting a resource to the access point, the access point characterized in that the request with the protection of the resource.
24. The method of claim 23, wherein

    The first station,

    And a bit value indicating whether to request the protection of the resource to the access point each time the resource is requested.
25. The method of claim 23, wherein

    And a bit value indicating whether to request the protection of the resource is included in a control field or a request type field of a TWT element and transmitted.
26. The method of claim 23, wherein

    The first station is a target wake time (TWT) station,

    The resource is an access point, characterized in that resources related to TWT.
27. The method of claim 24,

    The communication unit,

    And upon receiving a request for a resource from the first station, sending response data indicating whether the requested resource is to be protected to the first station.
28. The method of claim 22,

    The control unit,

    And determining resource allocation information for limiting channel access of the second station in a time interval for channel access of the first station.
29. The method of claim 22,

    The resource allocation information,

    Access information for the limited access window for protecting the resource of the first station.
30. The method of claim 22,

    The communication unit,

    Receiving control data indicating whether resource protection is requested from the first station,

    The control unit,

    Determining whether the first station has requested resource protection based on the control data, and when the first station requests resource protection, setting the time interval for which the first station has requested protection as a limited access window; Determining access information.
31. A communication unit for receiving resource protection request data from a station that does not refer to Traffic Indication Map (TIM) information; And

    A control unit for generating resource allocation information for protecting the resource requested by the station with a restricted access window (RAW) when receiving the request data,

    And the communication unit broadcasts the resource allocation information.
32. The method of claim 31, wherein

    The station,

    When requesting a resource to the access point, the access point characterized in that the request with the protection of the resource.
33. 33. The method of claim 32,

    The station,

    And a bit value indicating whether the resource is requested to be protected is included in a control field or a request type field of a TWT element and transmitted to the access point.

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