WO2019093745A1 - Method for transmitting or receiving frames in wireless lan system and apparatus therefor - Google Patents

Abstract

A method for transmitting a wake up radio (WUR) frame by an access point (AP) in a wireless LAN (WLAN) system according to an embodiment of the present invention comprises a step of determining a WUR ID (WID) to be included in a MAC header of a WUR frame for broadcast wake-up; and a step of transmitting the WUR frame including the determined WID, wherein the AP can determine the WID on the basis of whether the purpose of the broadcast wake-up is a first purpose for instructing a basic service set (BSS) parameter update to a station (STA) or a second purpose for instructing the STA to receive the broadcast data frame on primary connectivity radio (PCR).

Description

Method and apparatus for transmitting or receiving frames in a wireless LAN system

The present invention relates to a wireless LAN system, and more particularly, to a method and apparatus for transmitting or receiving a WAK (wake up radio) frame for waking up a primary connectivity radio (PCR).

The standard for wireless LAN technology is being developed as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a and b 2.4. GHz or 5 GHz, the IEEE 802.11b provides a transmission rate of 11 Mbps, and the IEEE 802.11a provides a transmission rate of 54 Mbps. IEEE 802.11g employs Orthogonal Frequency-Division Multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n employs multiple input multiple output (OFDM), or OFDM (MIMO-OFDM), and provides transmission speeds of 300 Mbps for four spatial streams. IEEE 802.11n supports channel bandwidth up to 40 MHz, which in this case provides a transmission rate of 600 Mbps.

The IEEE 802.11ax standard, which supports a maximum of 160 MHz bandwidth and supports 8 spatial streams, supports a maximum speed of 1 Gbit / s, and discusses IEEE 802.11ax standardization.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a WUR frame transmission / reception method and apparatus for instructing a broadcast wake-up and a STA related operation more accurately and efficiently.

The present invention is not limited to the above-described technical problems, and other technical problems can be deduced from the embodiments of the present invention.

According to another aspect of the present invention, there is provided a method of transmitting a WAK (Wake up Radio) frame in an access point (AP) in a wireless local area network (WLAN) Determining a WUR ID (WID) to be included in the MAC header; And transmitting the WUR frame including the determined WID, wherein the AP is further configured to determine whether the purpose of the broadcast wake-up is a first purpose for instructing a station (STA) to update a basic service set (BSS) Or a second purpose for instructing the STA to receive a broadcast data frame on a primary connectivity radio (PCR).

According to another aspect of the present invention, there is provided a method of receiving a wake up radio (WUR) frame from a station in a wireless local area network (WLAN) system, the method comprising: receiving a WUR frame for broadcast wake- Receiving; Obtaining a WUR ID (WID) included in a MAC header of the WUR frame; And a second target for receiving a broadcast data frame on a primary connectivity radio (PCR) based on the obtained WID, wherein the object of the broadcast wake-up is a first purpose for updating a basic service set (BSS) Can be determined.

According to another aspect of the present invention, there is provided an access point (AP) for transmitting a WAK (Wake up Radio) frame according to another aspect of the present invention includes a WUR ID to be included in a MAC header of a WUR frame for broadcast wake- WID); And a transmitter for transmitting the WUR frame including the determined WID, wherein the processor is further configured to determine whether a purpose of the broadcast wake-up is a first purpose for instructing a station (STA) to update a basic service set (BSS) Or a second purpose for instructing the STA to receive a broadcast data frame on a primary connectivity radio (PCR).

The AP sets a first range of the entire WID area to an individual STA ID area and sets a second range to a group ID (GID) area, wherein the WUR frame for the broadcast wakeup The WID to be included in the MAC header can be determined in the GID area.

Wherein the WID is determined to be a first special value if the purpose of the broadcast wake-up is a first purpose to instruct the BSS parameter update, and the purpose of the broadcast wake-up is to receive a broadcast data frame on the PCR The WID may be determined as a second special value.

The first special value and the second special value may not be allocated to an individual STA ID or a group ID (GID).

If the purpose of the broadcast wakeup includes both the first and second purposes, the WID may be determined as a third special value.

The first special value may be 0 or a partial BSSID, the second special value may be 1 or a partial BSSID + 1, and the third special value may be 2 or a partial BSSID + 2.

If it is determined that the purpose of the broadcast wake-up is the first purpose for updating the BSS parameter, the STA may receive the beacon frame on the PCR and update the BSS parameter based on the received beacon frame.

If it is determined that the purpose of the broadcast wakeup is a second purpose for receiving a broadcast data frame on the PCR, the STA may return to the WUR mode after receiving the broadcast data frame.

According to an embodiment of the present invention, since the WID is determined according to the purpose of the broadcast wakeup, the STA that receives the WUR frame for broadcast wakeup can clearly determine the action to be performed on the PCR through the WID have.

Other technical advantages than the above-described technical effects can be deduced from the embodiments of the present invention.

1 is a diagram showing an example of a configuration of a wireless LAN system.

2 is a diagram showing another example of the configuration of the wireless LAN system.

3 is a diagram for explaining a general link setup process.

4 is a diagram for explaining a backoff process.

5 is a diagram for explaining hidden nodes and exposed nodes.

6 is a diagram for explaining RTS and CTS.

7 to 9 are diagrams for explaining the operation of the STA that has received the TIM.

10 is a diagram for explaining an example of a frame structure used in the IEEE 802.11 system.

11 is a diagram for explaining a WUR receiver usable in a wireless LAN system (e.g., 802.11).

12 is a diagram for explaining the operation of the WUR receiver.

13 shows an example of a WUR packet.

14 illustrates a waveform for a WUR packet.

15 is a diagram for explaining a WUR packet generated using an OFDM transmitter of a wireless LAN.

Figure 16 illustrates the structure of a WUR receiver.

17 shows a WUR packet according to an example of the present invention.

18 shows a WUR packet according to another example of the present invention.

19 illustrates a method for transmitting or receiving a WUR frame according to an embodiment of the present invention.

20 is a view for explaining an apparatus according to an embodiment of the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description, together with the accompanying drawings, is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form around the core functions of each structure and device in order to avoid obscuring the concepts of the present invention.

As described above, the following description relates to a method and apparatus for efficiently utilizing a channel having a wide bandwidth in a wireless LAN system. To this end, a wireless LAN system to which the present invention is applied will be described in detail.

1 is a diagram showing an example of a configuration of a wireless LAN system.

As shown in FIG. 1, a WLAN system includes one or more Basic Service Sets (BSSs). A BSS is a collection of stations (STAs) that can successfully communicate and synchronize with each other.

An STA is a logical entity that includes a medium access control (MAC) and a physical layer interface to a wireless medium. The STA includes an access point (AP) and a non-AP STA (Non-AP Station) . A portable terminal operated by a user in the STA is a non-AP STA, and sometimes referred to as a non-AP STA. The non-AP STA may be a terminal, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile terminal, May also be referred to as another name such as a Mobile Subscriber Unit.

An AP is an entity that provides a connection to a distribution system (DS) via a wireless medium to an associated station (STA). The AP may be referred to as a centralized controller, a base station (BS), a Node-B, a base transceiver system (BTS), a site controller, or the like.

The BSS can be divided into an infrastructure BSS and an independent BSS (IBSS).

The BBS shown in FIG. 1 is an IBSS. The IBSS means a BSS that does not include an AP, and does not include an AP, so a connection to the DS is not allowed and forms a self-contained network.

2 is a diagram showing another example of the configuration of the wireless LAN system.

The BSS shown in FIG. 2 is an infrastructure BSS. The infrastructure BSS includes one or more STAs and APs. In the infrastructure BSS, communication between non-AP STAs is performed via an AP, but direct communication between non-AP STAs is possible when a direct link is established between non-AP STAs.

As shown in FIG. 2, a plurality of infrastructure BSSs may be interconnected via DS. A plurality of BSSs connected through a DS are referred to as an extended service set (ESS). The STAs included in the ESS can communicate with each other, and within the same ESS, the non-AP STA can move from one BSS to another while seamlessly communicating.

The DS is a mechanism for connecting a plurality of APs. It is not necessarily a network, and there is no limitation on the form of DS if it can provide a predetermined distribution service. For example, the DS may be a wireless network such as a mesh network, or may be a physical structure that links APs together.

Hierarchy

The operation of the STA operating in the wireless LAN system can be described in terms of the layer structure. In terms of device configuration, the hierarchy can be implemented by a processor. The STA may have a plurality of hierarchical structures. For example, the hierarchical structure covered in the 802.11 standard document is mainly a MAC sublayer and a physical (PHY) layer on a DLL (Data Link Layer). The PHY may include a Physical Layer Convergence Procedure (PLCP) entity, a PMD (Physical Medium Dependent) entity, and the like. The MAC sublayer and the PHY conceptually include management entities called a MAC sublayer management entity (MLME) and a physical layer management entity (PLME), respectively. These entities provide a layer management service interface in which a layer management function operates .

In order to provide correct MAC operation, a Station Management Entity (SME) exists in each STA. An SME is a layer-independent entity that may be present in a separate management plane or may appear to be off-the-side. Although the exact functions of the SME are not described in detail in this document, they generally include the ability to collect layer-dependent states from various Layer Management Entities (LMEs) and to set similar values for layer-specific parameters It can be seen as responsible. An SME typically performs these functions on behalf of a generic system management entity and can implement a standard management protocol.

The aforementioned entities interact in various ways. For example, they can interact by exchanging GET / SET primitives between entities. A primitive is a set of elements or parameters related to a particular purpose. The XX-GET.request primitive is used to request the value of a given MIB attribute. The XX-GET.confirm primitive returns the appropriate MIB attribute information value if the Status is "Success", otherwise it is used to return an error indication in the Status field. The XX-SET.request primitive is used to request that the indicated MIB attribute be set to the given value. If the MIB attribute indicates a specific operation, it is requested that the corresponding operation be performed. The XX-SET.confirm primitive confirms that the indicated MIB attribute is set to the requested value if the status is "success", otherwise it is used to return an error condition to the status field. If the MIB attribute indicates a specific operation, this confirms that the corresponding operation has been performed.

In addition, MLME and SME can exchange various MLME_GET / SET primitives through MLME_SAP (Service Access Point). In addition, various PLME_GET / SET primitives can be exchanged between PLME and SME through PLME_SAP and exchanged between MLME and PLME through MLME-PLME_SAP.

link set up  process

3 is a diagram for explaining a general link setup process.

In order for a STA to set up a link to a network and transmit and receive data, the STA first discovers a network, performs authentication, establishes an association, establishes an authentication procedure for security, . The link setup process may be referred to as a session initiation process or a session setup process. Also, the process of discovery, authentication, association, and security setting of the link setup process may be collectively referred to as an association process.

An exemplary link setup procedure will be described with reference to FIG.

In step S510, the STA can perform a network discovery operation. The network discovery operation may include a scanning operation of the STA. In other words, in order for the STA to access the network, it must find a network that can participate. The STA must identify a compatible network before joining the wireless network. The process of identifying a network in a specific area is called scanning.

The scanning methods include active scanning and passive scanning.

FIG. 3 illustrates a network discovery operation that includes an exemplary active scanning process. The STA performing the scanning in the active scanning transmits the probe request frame and waits for a response in order to search for the existence of an AP in the surroundings while moving the channels. The responder sends a probe response frame in response to the probe request frame to the STA that transmitted the probe request frame. Here, the responder may be the STA that last transmitted the beacon frame in the BSS of the channel being scanned. In the BSS, the AP transmits the beacon frame, so the AP becomes the responder. In the IBSS, the STAs in the IBSS transmit the beacon frame while the beacon frame is transmitted. For example, the STA that transmits the probe request frame on channel 1 and receives the probe response frame on channel 1 stores the BSS-related information included in the received probe response frame and transmits the next channel (for example, Channel) and perform scanning in the same manner (i.e., transmitting / receiving a probe request / response on the second channel).

Although not shown in Fig. 3, the scanning operation may be performed in a passive scanning manner. In passive scanning, the STA performing the scanning waits for the beacon frame while moving the channels. A beacon frame is one of the management frames in IEEE 802.11, and is transmitted periodically to notify the presence of a wireless network and allow the STA performing the scanning to find the wireless network and participate in the wireless network. In the BSS, the AP periodically transmits the beacon frame. In the IBSS, the beacon frames are transmitted while the STAs in the IBSS are running. Upon receiving the beacon frame, the scanning STA stores information on the BSS included in the beacon frame and records beacon frame information on each channel while moving to another channel. The STA receiving the beacon frame stores the BSS-related information included in the received beacon frame, moves to the next channel, and performs scanning in the next channel in the same manner.

Comparing active scanning with passive scanning, active scanning has the advantage of less delay and less power consumption than passive scanning.

After the STA finds the network, the authentication procedure may be performed in step S520. This authentication process can be referred to as a first authentication process in order to clearly distinguish from the security setup operation in step S540 described later.

The authentication process includes an STA transmitting an authentication request frame to the AP, and an AP transmitting an authentication response frame to the STA in response to the authentication request frame. The authentication frame used for the authentication request / response corresponds to the management frame.

The authentication frame includes an authentication algorithm number, an authentication transaction sequence number, a status code, a challenge text, a robust security network (RSN), a finite cyclic group Group), and the like. This corresponds to some examples of information that may be included in the authentication request / response frame, may be replaced by other information, or may include additional information.

The STA may send an authentication request frame to the AP. Based on the information included in the received authentication request frame, the AP can determine whether or not to allow authentication for the STA. The AP can provide the result of the authentication process to the STA through the authentication response frame.

After the STA has been successfully authenticated, the association process may be performed in step S530. The association process includes an STA transmitting an association request frame to an AP, and an AP transmitting an association response frame to the STA in response to the association request frame.

For example, the association request frame may include information related to various capabilities, a listening interval, a service set identifier (SSID), supported rates, supported channels, an RSN, , Supported operating classes, TIM broadcast request, interworking service capability, and the like.

For example, the association response frame may include information related to various capabilities, a status code, an association ID (AID), a support rate, an enhanced distributed channel access (EDCA) parameter set, a Received Channel Power Indicator (RCPI) A timeout interval (an association comeback time), a overlapping BSS scan parameter, a TIM broadcast response, a QoS map, and the like.

This corresponds to some examples of information that may be included in the association request / response frame, may be replaced by other information, or may include additional information.

After the STA is successfully associated with the network, a security setup procedure may be performed at step S540. The security setup process of step S540 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response. The authentication process of step S520 may be referred to as a first authentication process, May also be referred to simply as an authentication process.

The security setup process of step S540 may include a private key setup through 4-way handshaking over an Extensible Authentication Protocol over LAN (EAPOL) frame, for example . In addition, the security setup process may be performed according to a security scheme not defined in the IEEE 802.11 standard.

Medium access mechanism

In a wireless LAN system compliant with IEEE 802.11, the basic access mechanism of Medium Access Control (MAC) is a CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) mechanism. The CSMA / CA mechanism is also referred to as the Distributed Coordination Function (DCF) of the IEEE 802.11 MAC, which basically adopts a "listen before talk" access mechanism. According to this type of access mechanism, the AP and / or the STA may sense a radio channel or medium for a predetermined time interval (e.g., DCF Inter-Frame Space (DIFS) If the medium is judged to be in an idle status, the frame transmission is started through the corresponding medium, whereas if the medium is occupied status, The AP and / or the STA does not start its own transmission but sets a delay period (for example, an arbitrary backoff period) for the medium access and waits for a frame transmission after waiting With the application of an arbitrary backoff period, several STAs are expected to attempt frame transmission after waiting for different time periods, so that collisions can be minimized.

In addition, the IEEE 802.11 MAC protocol provides HCF (Hybrid Coordination Function). The HCF is based on the DCF and the PCF (Point Coordination Function). The PCF is a polling-based, synchronous access scheme that refers to periodically polling all receiving APs and / or STAs to receive data frames. In addition, HCF has EDCA (Enhanced Distributed Channel Access) and HCCA (HCF Controlled Channel Access). EDCA is a contention-based access method for a provider to provide data frames to a large number of users, and HCCA uses a contention-based channel access method using a polling mechanism. In addition, the HCF includes a medium access mechanism for improving QoS (Quality of Service) of the WLAN, and can transmit QoS data in both a contention period (CP) and a contention free period (CFP).

4 is a diagram for explaining a backoff process.

The operation based on an arbitrary backoff period will be described with reference to FIG. When a medium that is in an occupy or busy state is changed to an idle state, several STAs may attempt to transmit data (or frames). At this time, as a method for minimizing the collision, each of the STAs may attempt to transmit after selecting an arbitrary backoff count and waiting for a corresponding slot time. An arbitrary backoff count has a packet number value and can be determined to be one of values in the range of 0 to CW. Here, CW is a contention window parameter value. The CW parameter is given an initial value of CWmin, but it can take a value twice in case of transmission failure (for example, in the case of not receiving an ACK for a transmitted frame). If the CW parameter value is CWmax, data transmission can be attempted while maintaining the CWmax value until the data transfer is successful. If the data transfer is successful, the CWmin value is reset to the CWmin value. The values of CW, CWmin and CWmax are preferably set to 2 ⁿ -1 (n = 0, 1, 2, ...).

When an arbitrary backoff process is started, the STA continuously monitors the medium while counting down the backoff slot according to the determined backoff count value. When the medium is monitored in the occupied state, the countdown is stopped and waited, and when the medium is idle, the remaining countdown is resumed.

In the example of FIG. 4, when a packet to be transmitted to the MAC of the STA3 arrives, the STA3 can confirm that the medium is idle by DIFS and transmit the frame immediately. Meanwhile, the remaining STAs monitor and wait for the medium to be in a busy state. In the meanwhile, data to be transmitted may also occur in each of STA1, STA2 and STA5, and each STA waits for DIFS when the medium is monitored as idle, and then counts down the backoff slot according to the arbitrary backoff count value selected by each STA. Can be performed. In the example of FIG. 4, STA2 selects the smallest backoff count value, and STA1 selects the largest backoff count value. That is, the case where the remaining backoff time of the STA5 is shorter than the remaining backoff time of the STA1 at the time when the STA2 finishes the backoff count and starts the frame transmission is illustrated. STA1 and STA5 stop countdown and wait for a while while STA2 occupies the medium. When the occupation of STA2 is ended and the medium becomes idle again, STA1 and STA5 wait for DIFS and then resume the stopped backoff count. That is, the frame transmission can be started after counting down the remaining backoff slots by the remaining backoff time. Since the remaining backoff time of STA5 is shorter than STA1, STA5 starts frame transmission. On the other hand, data to be transmitted may also occur in the STA 4 while the STA 2 occupies the medium. At this time, in STA4, when the medium becomes idle, it waits for DIFS, counts down according to an arbitrary backoff count value selected by the STA4, and starts frame transmission. In the example of FIG. 6, the remaining backoff time of STA5 coincides with the arbitrary backoff count value of STA4, in which case a collision may occur between STA4 and STA5. If a collision occurs, neither STA4 nor STA5 receive an ACK, and data transmission fails. In this case, STA4 and STA5 can double the CW value, then select an arbitrary backoff count value and perform a countdown. On the other hand, the STA1 waits while the medium is occupied due to the transmission of the STA4 and the STA5, waits for the DIFS when the medium becomes idle, and starts frame transmission after the remaining backoff time.

STA Sensing  action

As described above, the CSMA / CA mechanism includes virtual carrier sensing in addition to physical carrier sensing in which the AP and / or STA directly senses the medium. Virtual carrier sensing is intended to compensate for problems that may occur in media access, such as hidden node problems. For the virtual carrier sensing, the MAC of the wireless LAN system may use a network allocation vector (NAV). NAV is a value indicating to another AP and / or STA the time remaining until the media and / or the STA that is currently using or authorized to use the media are available. Therefore, the value set to NAV corresponds to the period in which the medium is scheduled to be used by the AP and / or the STA that transmits the frame, and the STA receiving the NAV value is prohibited from accessing the medium during the corresponding period. The NAV may be set according to the value of the " duration " field of the MAC header of the frame, for example.

In addition, a robust collision detection mechanism has been introduced to reduce the probability of collision. This will be described with reference to Figs. 5 and 7. Fig. The actual carrier sensing range and the transmission range may not be the same, but are assumed to be the same for convenience of explanation.

5 is a diagram for explaining hidden nodes and exposed nodes.

FIG. 5A is an example of a hidden node, and STA A and STA B are in communication and STA C has information to be transmitted. Specifically, STA A is transmitting information to STA B, but it can be determined that STA C is idle when performing carrier sensing before sending data to STA B. This is because the STA A transmission (ie, media occupancy) may not be sensed at the STA C location. In this case, STA B receives information of STA A and STA C at the same time, so that collision occurs. In this case, STA A is a hidden node of STA C.

FIG. 5B is an example of an exposed node, and STA B is a case of transmitting data to STA A, and STA C has information to be transmitted in STA D. FIG. In this case, if the STA C carries out the carrier sensing, it can be determined that the medium is occupied due to the transmission of the STA B. Accordingly, even if STA C has information to be transmitted to STA D, it is sensed that the media is occupied, and therefore, it is necessary to wait until the medium becomes idle. However, since the STA A is actually out of the transmission range of the STA C, the transmission from the STA C and the transmission from the STA B may not collide with each other in the STA A. Therefore, the STA C is not necessary until the STA B stops transmitting It is to wait. In this case, STA C can be regarded as an exposed node of STA B.

6 is a diagram for explaining RTS and CTS.

5, short signaling packets such as RTS (request to send) and CTS (clear to send) can be used in order to efficiently use the collision avoidance mechanism. The RTS / CTS between the two STAs may allow the surrounding STA (s) to overhear, allowing the surrounding STA (s) to consider whether to transmit information between the two STAs. For example, if the STA to which data is to be transmitted transmits an RTS frame to the STA receiving the data, the STA receiving the data can notify that it will receive the data by transmitting the CTS frame to surrounding STAs.

FIG. 6A is an example of a method for solving a hidden node problem, and it is assumed that both STA A and STA C attempt to transmit data to STA B. FIG. When STA A sends RTS to STA B, STA B transmits CTS to both STA A and STA C around it. As a result, STA C waits until the data transmission of STA A and STA B is completed, thereby avoiding collision.

6 (b) is an illustration of a method for solving the exposed node problem, where STA C overrides the RTS / CTS transmission between STA A and STA B, D, the collision does not occur. That is, STA B transmits RTS to all surrounding STAs, and only STA A having data to be transmitted transmits CTS. Since STA C only receives RTS and does not receive CTS of STA A, it can be seen that STA A is outside the carrier sensing of STC C.

Power Management

As described above, in the wireless LAN system, the STA must perform channel sensing before performing transmission / reception, and always sensing the channel causes continuous power consumption of the STA. The power consumption in the reception state does not differ much from the power consumption in the transmission state, and maintaining the reception state is also a large burden on the STA which is limited in power (that is, operated by the battery). Thus, if the STA keeps listening for sustained channel sensing, it will inefficiently consume power without special benefits in terms of WLAN throughput. To solve this problem, the wireless LAN system supports the power management (PM) mode of the STA.

The STA's power management mode is divided into an active mode and a power save (PS) mode. STA basically operates in active mode. An STA operating in active mode maintains an awake state. The awake state is a state in which normal operation such as frame transmission / reception and channel scanning is possible. Meanwhile, the STA operating in the PS mode operates by switching between a sleep state (or a doze state) and an awake state. The STA operating in the sleep state operates with minimal power and does not perform frame scanning nor transmission and reception of frames.

As the STA sleeps as long as possible, power consumption is reduced, so the STA increases the operating time. However, since it is impossible to transmit / receive frames in the sleep state, it can not be operated unconditionally for a long time. If the STA operating in the sleep state exists in the frame to be transmitted to the AP, it can switch to the awake state and transmit the frame. On the other hand, when there is a frame to be transmitted to the STA by the AP, the STA in the sleep state can not receive it, and it is unknown that there is a frame to receive. Therefore, the STA may need to switch to the awake state according to a certain period to know whether there is a frame to be transmitted to it (and to receive it if it exists).

The AP may transmit a beacon frame to the STAs in the BSS at regular intervals. The beacon frame may include a Traffic Indication Map (TIM) information element. The TIM information element may include information that indicates that the AP has buffered traffic for the STAs associated with it and will transmit the frame. The TIM element includes a TIM used for indicating a unicast frame and a delivery traffic indication map (DTIM) used for indicating a multicast or broadcast frame.

7 to 9 are views for explaining the operation of the STA receiving the TIM in detail.

Referring to FIG. 7, in order to receive a beacon frame including a TIM from an AP, the STA changes from a sleep state to an awake state, and analyzes the received TIM element to find that there is buffered traffic to be transmitted to the STA . After the STA performs contending with other STAs for medium access for PS-Poll frame transmission, it may transmit a PS-Poll frame to request AP to transmit data frame. The AP receiving the PS-Poll frame transmitted by the STA can transmit the frame to the STA. The STA may receive a data frame and send an acknowledgment (ACK) frame to the AP. The STA can then be switched to the sleep state again.

As shown in FIG. 7, the AP operates according to an immediate response scheme for transmitting a data frame after a predetermined time (for example, SIFS (Short Inter-Frame Space)) after receiving the PS-Poll frame from the STA . On the other hand, if the AP does not prepare the data frame to be transmitted to the STA after receiving the PS-Poll frame for the SIFS time, the AP can operate according to a deferred response method, which will be described with reference to FIG.

In the example of FIG. 8, the operation of switching the STA from the sleep state to the awake state, receiving the TIM from the AP, competing, and transmitting the PS-Poll frame to the AP is the same as the example of FIG. If the AP receives the PS-Poll frame and fails to prepare the data frame for SIFS, it can send an ACK frame to the STA instead of transmitting the data frame. After the AP transmits the ACK frame and the data frame is ready, it can transmit the data frame to the STA after performing the contention. The STA transmits an ACK frame indicating that the data frame has been successfully received to the AP, and can be switched to the sleep state.

Figure 9 is an example of an AP transmitting a DTIM. STAs may transition from the sleep state to the awake state to receive a beacon frame containing the DTIM element from the AP. STAs can know that a multicast / broadcast frame will be transmitted through the received DTIM. The AP can transmit data (i.e., multicast / broadcast frame) directly without transmitting / receiving a PS-Poll frame after transmitting a beacon frame including DTIM. The STAs may receive data while continuing to hold the awake state after receiving the beacon frame including the DTIM, and may switch to the sleep state again after the data reception is completed.

Frame structure general

10 is a diagram for explaining an example of a frame structure used in the IEEE 802.11 system.

The Physical Layer Protocol Data Unit (PPDU) frame format may include a Short Training Field (STF) field, a Long Training Field (LTF) field, a SIGN (SIGNAL) field, and a Data field. The most basic (e.g., non-HT (High Throughput)) PPDU frame format may consist of L-STF (Legacy-STF), L-LTF (Legacy-LTF), SIG field and data field only.

STF is a signal for signal detection, AGC (Automatic Gain Control), diversity selection, precise time synchronization, etc., and LTF is a signal for channel estimation and frequency error estimation. STF and LTF may be collectively referred to as a PLCP preamble, and the PLCP preamble may be a signal for synchronization and channel estimation of the OFDM physical layer.

The SIG field may include a RATE field and a LENGTH field. The RATE field may contain information on the modulation and coding rate of the data. The LENGTH field may contain information on the length of the data. Additionally, the SIG field may include a parity bit, a SIG TAIL bit, and the like.

The data field may include a SERVICE field, a physical layer service data unit (PSDU), a PPDU TAIL bit, and may also include a padding bit if necessary. Some bits in the SERVICE field may be used for synchronization of the descrambler at the receiving end. The PSDU corresponds to an MPDU (MAC Protocol Data Unit) defined in the MAC layer and may include data generated / used in an upper layer. The PPDU TAIL bit can be used to return the encoder to the 0 state. The padding bits may be used to match the length of the data field to a predetermined unit.

The MPDU is defined according to various MAC frame formats, and the basic MAC frame is composed of a MAC header, a frame body, and a frame check sequence (FCS). The MAC frame is composed of MPDUs and can be transmitted / received via the PSDU of the data part of the PPDU frame format.

The MAC header includes a Frame Control field, a Duration / ID field, an Address field, and the like. The frame control field may contain control information necessary for frame transmission / reception. The period / ID field may be set to a time for transmitting the frame or the like.

The period / ID field included in the MAC header can be set to a 16-bit length (e.b., B0 to B15). The content included in the period / ID field may vary depending on the frame type and subtype, whether it is transmitted during the contention free period (CFP), the QoS capability of the transmitting STA, and the like. (i) In a control frame whose subtype is PS-Poll, the period / ID field may contain the AID of the transmitting STA (e.g., via 14 LSB bits) and 2 MSB bits may be set to one. (ii) In frames transmitted during the CFP by a point coordinator (PC) or a non-QoS STA, the duration / ID field may be set to a fixed value (e.g., 32768). (iii) In other frames transmitted by other non-QoS STAs or control frames transmitted by the QoS STA, the duration / ID field may include a duration value defined for each frame type. In a data frame or a management frame transmitted by the QoS STA, the duration / ID field may include a duration value defined for each frame type. For example, if B15 = 0 in the duration / ID field indicates that the duration / ID field is used to indicate TXOP Duration, B0-B14 can be used to indicate the actual TXOP duration. The actual TXOP Duration indicated by B0 to B14 may be any of 0 to 32767, and the unit may be microseconds (us). However, when the period / ID field indicates a fixed TXOP Duration value (e.g., 32768), B15 = 1 and B0 to B14 = 0. In addition, if B14 = 1 and B15 = 1 are set, the period / ID field is used to indicate AID, and B0 to B13 indicate one of AIDs from 1 to 2007. The specific contents of the Sequence Control, QoS Control, and HT Control subfields of the MAC header can refer to the IEEE 802.11 standard document.

 The frame control field of the MAC header may include Protocol Version, Type, Subtype, To DS, From DS, More Fragment, Retry, Power Management, More Data, Protected Frame, Order subfields. The contents of each subfield of the frame control field may reference an IEEE 802.11 standard document.

WUR (Wake-Up Radio)

Referring to FIG. 11, a general description of a wake-up radio receiver (WURx) compatible with a wireless LAN system (e.g., 802.11) will be described.

11, the STA includes a primary connectivity radio (PCR) (eg, IEEE 802.11a / b / g / n / ac / ax wireless LAN) and a wake- WUR) (eg, IEEE 802.11ba).

The PCR is used for data transmission and reception, and can be turned off when there is no data to be transmitted or received. When the PCR is turned off as described above, the WURx of the STA can wake up the PCR when there is a packet to be received. Therefore, user data is transmitted and received through PCR.

WURx is not used for user data, but can only wake up the PCR transceiver. WURx can be in the form of a simple receiver without a transmitter and is active while PCR is off. The target power consumption of WURx in the active state preferably does not exceed 100 microW (uW). In order to operate at such a low power, a simple modulation scheme such as an on-off keying (OOK) scheme can be used, and a narrow bandwidth (e.g., 4 MHz, 5 MHz) can be used. The coverage range (e.g., distance) to which WURx is targeted may currently be equivalent to 802.11.

12 is a diagram for explaining the design and operation of the WUR packet.

Referring to FIG. 12, a WUR packet may include a PCR part 1200 and a WUR part 1205.

The PCR part 1200 is for coexistence with a legacy WLAN system, and the PCR part may be referred to as a wireless LAN preamble. At least one or more of the L-STF, L-LTF, and L-SIG of the legacy wireless LAN may be included in the PCR part 1200 to protect WUR packets from other PCR STAs. Accordingly, the 3rd party legacy STA can know that the WUR packet is not intended for itself through the PCR part 1200 of the WUR packet, but the medium of the PCR is occupied by another STA. However, WURx does not decode the PCR part of the WUR packet. This is because WURx that supports narrowband and OOK demodulation does not support the reception of PCR signals.

At least a portion of the WUR part 1205 may be modulated in an on-off keying (OOK) manner. In one example, the WUR part may include at least one of a WUR preamble, a MAC header (e.g., a recipient address, etc.), a frame body, and a frame check sequence (FCS). On the other hand, OOK modulation may be performed by modifying the OFDM transmitter.

WURx 1210 consumes very little power, less than 100 uW, as described above, and can be implemented with a small and simple OOK demodulator.

Since the WUR packet needs to be designed to be compatible with the WLAN system, the WUR packet includes a preamble (eg, OFDM scheme) of a legacy wireless LAN and a new LP-WUR signal waveform (eg, OOK scheme) can do.

13 shows an example of a WUR packet. The WUR packet of FIG. 13 includes a PCR part (e.g., a legacy wireless LAN preamble) for coexistence with a legacy STA.

Referring to FIG. 13, the legacy wireless LAN preamble may include L-STF, L-LTF, and L-SIG. The WLAN STA (eg, 3rd Party) can detect the start of a WUR packet through L-STF. Also, the wireless LAN STA (eg, 3rd party) can identify the end of the WUR packet through the L-SIG. For example, the L-SIG field may indicate the length of the payload of the WUR packet (e.g., OOK modulated).

The WUR part may include at least one of a WUR preamble, a MAC header, a frame body, and an FCS. The WUR preamble may include, for example, a PN sequence. The MAC header may include a receiver address. The frame body may contain other information needed for wake-up. The FCS may include a cyclic redundancy check (CRC).

FIG. 14 illustrates a waveform for the WUR packet of FIG. Referring to Fig. 14, in the OOK modulated WUR part, one bit can be transmitted per 1 OFDM symbol length (e.g., 4 usec). Thus, the data rate of the WUR part may be 250 kbps.

15 is a diagram for explaining generation of a WUR packet using an OFDM transmitter of a wireless LAN. In the wireless LAN, a phase shift keying (PSK) -OFDM transmission scheme is used. However, generating a WUR packet by adding a separate OOK modulator for OOK modulation increases the implementation cost of the transmitter. Therefore, a method of generating an OOK modulated WUR packet by reusing an OFDM transmitter will be described.

According to the OOK modulation scheme, a bit value of 1 is modulated with a symbol (i.e., on) with a power equal to or higher than a threshold value, and a bit value of 0 is modulated with a symbol (i.e., off) with a power below a threshold value. Of course, conversely, it is also possible to define the bit value 1 as the power off.

In the OOK modulation scheme, the bit value 1/0 is indicated on / off of the power at the corresponding symbol position. This simple OOK modulation / demodulation scheme has the advantage of reducing the power consumed in signal detection / demodulation of the receiver and the cost for implementing it. In addition, OOK modulation to turn signals on and off may be performed by reusing existing OFDM transmitters.

The left graph of FIG. 15 shows the real part and the imaginary part of the normalized amplitude for one symbol period (e.g., 4 usec) for the OOK modulated bit value 1 by reusing the OFDM transmitter of the existing wireless LAN. lt; / RTI > shows an imaginary part. The OOK modulation result for the bit value 0 corresponds to the power off, so that the illustration is omitted.

The right graph of FIG. 15 shows normalized power spectral density (PSD) on the frequency domain for the OOK modulated bit value 1 by reusing the OFDM transmitter of the existing wireless LAN. For example, center 4 MHz in the band may be used for WUR. In FIG. 15, it is assumed that WUR operates at a 4 MHz bandwidth, but this is for convenience of explanation, and frequency bandwidths of different sizes may be used. However, it is desirable for WUR to operate at a bandwidth smaller than the operation bandwidth of the PCR (e.g., a conventional WLAN) for power reduction.

In FIG. 15, it is assumed that the subcarrier spacing (e.g., subcarrier spacing) is 312.5 kHz and the bandwidth of the OOK pulse corresponds to 13 subcarriers. The 13 subcarriers correspond to about 4 MHz (i.e., 4.06 MHz = 13 * 312.5 kHz) as mentioned above.

In the conventional OFDM transmitter, the input sequence of IFFT (inverse fast Fourier transform) is defined as s = {13 subcarrier tone sequence} and IFFT for the corresponding sequence s is performed as X _t = IFFT (s) When a CP (cyclic prefix) is attached, it becomes about 4 us symbol length.

The WUR packet may be referred to as a WUR signal, a WUR frame, or a WUR PPDU. The WUR packet may be a packet for broadcast / multicast (e.g., a WUR beacon) or a packet for unicast (e.g., a packet for waking up and awakening the WUR mode of a particular WUR STA).

Figure 16 illustrates the structure of a WURx (WUR receiver). Referring to FIG. 16, WURx may include a RF / analog front-end, a digital baseband processor, and a simple packet parser. 16 is an exemplary configuration, and the WUR receiver of the present invention is not limited to Fig.

In the following, a WLAN STA with a WUR receiver is briefly referred to as a WUR STA. The WUR STA may be referred to briefly as the STA.

WUR PPDU

As described above, in order to reduce the power consumption of the STA, the STA operates in the WUR mode and can PCR-off. When the AP receives the data to be transmitted to the WUR STA, the AP transmits the WUR packet to the STA to awaken the STA, and then transmits the data through the PCR.

WUR packets are encoded and transmitted in OOK, so they have a relatively low transmission rate. Therefore, it takes a relatively long time to transmit a small WUR packet. In a denied WLAN environment, when a WUR packet is transmitted to each STA on a one-to-one basis, an inefficiency of the network may be caused have. Therefore, the WUR packet needs to be efficiently designed considering such matters.

17 shows a WUR packet according to an embodiment of the present invention. Referring to FIG. 17, a WUR packet may include payloads of L-STF, L-LTF, L-SIG, and WUR packets.

Referring to FIG. 17, the WUR packet may include information on how the WUR STAs receiving the WUR packet perform a wake-up operation (hereinafter, referred to as a wake-up operation mode, WOM information) have. The WOM information may be included in the MAC header of the WUR packet as shown in FIG. 21, but in another example, the WOM information may be included in the frame body.

- WOM = 0: No wake-up (PCR is not turned on). The STA does not turn on the PCR after receiving the WUR packet. That is, the STA does not perform a wake up operation. For example, the WOM can be set to 00 (No wake-up) when the AP wishes to update only the system information through a WUR packet or transmits a WUR packet for simple keep alive check. However, the STA completes the reception of the corresponding WUR packet even if it does not wake up.

- WOM = 1: Wake up confirmation signal / frame (eg, PS-Poll) transmission. After the STA receives the WUR packet, it requests a wake up confirmation signal / frame (e.g., PS-Poll) transmission after turning on the PCR (i.e., after performing the wake up operation). When waking STAs to transmit Unicast data, set to 01 (PS-Poll transmission after wake up). It is set when the Receiver ID is set to an Individual ID or Group ID, or when the TIM is used to wake up a part of the STA.

- WOM = 2: Waiting for frame after wake up. After receiving the WUR packet, the STA turns on the PCR (i.e., performs the wake up operation) and waits for the reception of the PCR frame. For example, when an AP transmits a WUR packet to STAs and transmits broadcast / multicast data through a PCR, the WOM of the WUR packet can be set to 2. Alternatively, when the AP desires to transmit a trigger frame for group polling on a PCR such as UL MU, the WOM packet WOM can be set to 2. In addition, when polling a group, the AP may set the WOM of the corresponding WUR packet to 2 (ie, binary 10) even when transmitting a Unicast WUR packet via the Individual ID / address.

In another example of the present invention, whether to broadcast / multicast data reception or group polling transmission can be divided at Wake up mode = 2. In this case, WOM = 2 is set for the broadcast / multicast data reception, and WOM = 3 is set for the Group Polling transmission.

As another example, the WOM information may be defined as one bit. In this case, the 1-bit WOM information can indicate whether or not the WUR STA should awake after receiving the WUR packet.

- WOM = 0 (No wake-up indication): WOM = 0 can indicate that the WUR STA does not wake up after receiving the WUR packet, but keep WUR mode.

- WOM = 1 (Wake-up indication): WOM = 1 may indicate that the WUR STA should wake up after receiving the corresponding WUR packet. Therefore, the WUR STA performs the wake-up procedure after receiving the WUR packet.

18 shows a WUR packet according to another embodiment of the present invention. Referring to FIG. 18, the WOM information may be transmitted in the WUR preamble. The WUR preamble can be divided into a WU sequence and a WU SIG. 18 shows an example in which the wakeup operation mode information is transferred from the WUR preamble to the WU SIG field.

WOM information can be used for all formats such as WUR packet format structure structure where WUR contents start with Receiver Address / ID and WUR packet format structure where WUR contents start with Frame Type.

On the other hand, the WOM information need not necessarily be an explicit separate indicator, for example, the WOM information may be embedded in the frame type. For example, WOM information may be implicitly indicated through Frame Type information. The Frame Type indicating the WOM information implicitly can be defined as follows, for example.

- Frame Type = 0 indicates a Broadcast WUR packet that does not include Receiver ID, and can also indicate a Wake up request. For example, Frame Type = 0 may indicate that all WUR STAs belonging to the STA (e.g., AP) indicated by the Transmitter ID included in the WUR packet should be awakened upon receiving the corresponding WUR packet. In this case, the WUR STA may not transmit a wake up confirmation signal / frame (e.g., PS-Poll) to the AP after wake up. For example, when an AP transmits a broadcast data / frame (eg, Beacon, TIM, ...) such as DTIM traffic, the Frame Type can be set to zero.

- Frame Type = 1 is a Broadcast WUR packet that does not include Receiver ID and can indicate No wake-up. For example, Frame Type = 1 WUR An STA may receive only a WUR packet and indicate that it should not wake up. The AP can set the Frame Type to 1, for example, when transmitting the system information through a WUR packet or when transmitting a WUR packet for a keep alive check. WUR STA receiving WUR packet set to Frame Type = 1 can keep on off without turning on PCR. When the AP transmits system information through a WUR packet, the WUR STA can perform system information update based on information included in the frame (e.g., operating channel info, time alignment info, etc.). If the WUR packet is sent for Keep alive check, the WUR packet may not contain additional information (e.g., system information).

- Frame Type = 2 indicates that the receiver ID is included in the WUR packet, the size of the receiver ID is AID size (eg, 2 bytes or 12 bits), STA requests to perform the wake up procedure after receiving the corresponding WUR packet can do. After waking up, the STA can send a Wake up confirmation signal / frame (e.g., PS-Poll, QoS Null, Wakeup Notification frame). For example, the AID may be set to an individual AID, but may alternatively be set to Broadcast ID, Multicast / Group ID.

- Frame Type = 3 indicates that the receiver ID is included in the WUR packet, the size of the receiver ID is AID size (eg, 2 bytes or 12 bits), STA requests to perform the wake up procedure after receiving the corresponding WUR packet can do. However, unlike Frame Type = 2, when Frame Type = 3, STAs do not send Wake up confirmation signal / frame (eg, PS-Poll, QoS Null, Wakeup Notification frame) . For example, the AID may be set to Multicast / Group AID, but otherwise the AID may be set to Broadcast AID or Individual AID.

- Frame Type = 4 indicates that the receiver ID is included in the WUR packet, the size of the receiver ID is the MAC address size (eg, 6 bytes), and the STAs instruct the receiver to perform the wake up procedure after receiving the WUR packet have. After waking up, the STA may send a Wake up confirmation signal / frame (e.g., PS-Poll, QoS Null, Wakeup Notification frame). For example, the MAC address may be set to an individual MAC address, whereas the MAC address may be set to one of Broadcast / Multicast / Group MAC addresses.

- Frame Type = 5 indicates that the receiver ID is included in the WUR packet, the size of the receiver ID is the MAC address size (eg, 6 bytes), and the STA instructs the STA to perform the wake up procedure after receiving the WUR packet have. However, unlike Frame Type = 4, when Frame Type = 6, STAs do not transmit Wake up confirmation signal / frame (eg, PS-Poll, QoS Null, Wakeup Notification frame) . For example, the MAC address may be set to a multicast / group MAC address, but the MAC address may be set to an individual MAC address or a broadcast MAC address.

The frame types described above are illustrative, and the scope of rights of the present invention is not limited thereto, and other frame types may be added, or only some of the above frame types may be used. For example, when only one of the MAC address and the AID is used as the receiver address / ID, only one set of Frame Type = 2 & 3 and Frame Type 4 & 5 can be used.

Alternatively, the Frame Type is not defined separately and the WOM / Frame Type may be directly or indirectly indicated through other fields of the WUR packet. For example, in the WUR packet format where the Receiver ID is placed first in the WUR content, the WOM information may be embedded in the Receiver ID. As a more specific example, the WOM information indicated by the value of the receiver ID can be defined as follows.

- Receiver ID = Individual AID can be set, which indicates the wake up of the WUR STA corresponding to the individual AID. After the WUR STA wakes up, it can attempt to transmit a wake-up acknowledgment signal (e.g., PS-Poll, QoS Null, Wakeup Notification frame).

As mentioned above, even if AID is an individual AID, if the WOM information is included in the WUR frame like an individual AID, the AP will not wake up the WOM for the individual AID (eg, WOM = 0) (e.g., WOM = 2).

- Receiver ID = Broadcast AID, which can instruct all WUR STAs to wake up. For example, the broadcast AID may be 0, but is not limited thereto. As another example, the broadcast AID may be all 1s or partial BSSID or partial BSSID + x (x is an integer greater than 0). The WUR STAs may wait for a PCR frame reception without attempting to transmit a wake-up confirmation signal (e.g., PS-Poll, QoS Null, or Wakeup Notification frame) after wake up.

For example, a Broadcast ID (e.g., Broadcast AID) may be defined multiple (e.g., two or more) for different purposes. One Broadcast ID is for instructing a BSS parameter update, and the other Broadcast ID may be for instructing reception of a Broadcast data frame on PCR.

(i) When the STA receives a WUR frame containing a Broadcast ID indicating a BSS parameter update, the STA receives the PCR beacon frame by turning on the PCR. The STA performs a BSS parameter update based on the PCR beacon frame.

The broadcast ID indicating the BSS parameter update may be a WUR ID having a first special value among the WUR IDs. The WUR ID having the first special value may be, for example, a WUR ID having a zero or partial BSSID value, but is not limited thereto. In other words, the WUR ID corresponding to the first special value may mean a broadcast wake-up without reception of a broadcast data frame on PCR or a broadcast wake-up only for BSS parameter update.

(ii) Also, if the ID indicates a broadcast data frame reception / group addressed BU reception, the STA can turn on the PCR to perform a reception operation on the broadcast data / group address frame. After receiving the broadcast data / group addressed frame through the PCR, the STA can turn off the PCR to reduce power consumption.

The ID indicating the broadcast wake-up for reception of the broadcast / group addressed frame may be the WUR ID having the second special value among the WUR IDs. The WUR ID having the second special value may be, for example, a WUR ID having a value of 1 or partial BSSID + 1, but is not limited thereto.

(iii) In addition, one ID may be defined / used to indicate both broadcast data / group addressed frame reception and BSS parameter update. The ID for indicating both the broadcast data reception / group addressed frame and the BSS parameter update may be a WUR ID having a third special value among the WUR IDs. A WUR ID having a third special value may be, for example, but is not limited to, a WUR ID having a value of 2 or a partial BSSID + 2.

The AP shall assign the IDs (eg, 0, 1, 2, partial BSSID, partial BSSID + 1, or partial BSSID + 2 etc.) of the special value allocated for broadcast wakeup as in (i) It is better not to assign STA to unicast WID or multicast ID / group ID.

The IDs of the special values mentioned in (i) to (iii) are illustrative and other values may be used.

On the other hand, some of the full range of WUR IDs may be used for Group IDs, while others may be used for individual WIDs. A specific one of the group IDs can be used as an ID indicating broadcast wake-up for transmission of a broadcast addressed frame (/ group addressed frame). In this case, in the process of assigning the group ID, the AP can always assign the corresponding group ID to the STAs receiving the broadcast addressed frame. Upon receiving the wake-up frame transmitted based on the Group ID, the STA determines that the received wake-up frame indicates reception of the broadcast frame in the PCR, and may attempt to receive the broadcast addressed frame through the PCR. After the broadcast addressed frame is received, the STA can switch the PCR to the doze state.

- Receiver ID = Special AID. The special AID may be, for example, all bits set to 1 (= all 1s), 2047 or 2046, ... But the present invention is not limited thereto. The Special AID may instruct all WUR STAs to receive WUR packets but no wake up. For example, the WUR STA can maintain the WUR mode without turning on the PCR even if it receives the WUR packet. For example, if the WUR packet includes system information (eg, channel switch information, time alignment information, ...), the WUR STA may update the system information stored in the WUR STA based on the information contained in the WUR packet .

- Receiver ID = Group AID, which indicates that WUR STAs belonging to the group are to wake up. WUR STAs can wait for receiving a PCR frame without waking up and then attempting to transmit a wake-up confirmation signal (e.g., PS-Poll, QoS Null, Wakeup Notification frame). The PCR frame may be, for example, a multicast / group-cast frame, a trigger frame, or a group polling frame, but is not limited thereto.

FIG. 19 shows a flow of a WUR frame transmission / reception method according to an embodiment of the present invention.

Referring to FIG. 19, an AP may determine a WUR ID (WID) to be included in a MAC header of a WUR frame for broadcast wakeup (1905). The AP determines whether the purpose of the broadcast wake-up is the primary purpose of instructing the station (STA) to update the BSS (basic service set) parameter or to instruct the STA to receive the broadcast data frame on the PCR Lt; RTI ID = 0.0 > WID < / RTI >

The AP may transmit a WUR frame containing the determined WID (1910). The STA receives a WUR frame for broadcast wakeup.

The STA obtains the WUR ID (WID) included in the MAC header of the WUR frame (1915).

Based on the acquired WID, the STA determines whether the purpose of the broadcast wake-up is a first purpose for updating a basic service set (BSS) parameter or a second purpose for receiving a broadcast data frame on a primary connectivity radio (PCR) (1920).

The STA may receive the beacon frame on the PCR and / or receive the broadcast data frame (or Group Addressed frame) (1925) according to the determined purpose of the broadcast wake-up. If the purpose of the broadcast wake-up is determined to be the primary purpose for BSS parameter update, the STA may receive the beacon frame on the PCR and update the BSS parameter based on the received beacon frame.

If it is determined that the purpose of the broadcast wakeup is a second purpose for receiving a broadcast data frame on the PCR, the STA can return to the WUR mode after receiving the broadcast data frame.

The AP sets a first range of the entire WID area as an individual STA ID area and a second range as a group ID (GID) area, and sets a MAC header of a WUR frame for broadcast wakeup The WID to be included in the GID area can be determined.

If the purpose of the broadcast wake-up is the first purpose for indicating a BSS parameter update, then the WID is determined to be a first special value, and the purpose of the broadcast wake-up is to indicate to receive a broadcast data frame on the PCR For the second purpose, the WID can be determined as the second special value.

The first special value and the second special value may not be assigned to an individual STA ID or group ID (GID). If the purpose of the broadcast wake-up includes both the first and second purposes, the WID may be determined to a third special value. The first special value may be 0 or a partial BSSID, the second special value may be 1 or a partial BSSID +1, and the third special value may be 2 or a partial BSSID + 2.

20 is a view for explaining an apparatus for implementing the method as described above.

The wireless device 100 of FIG. 20 may correspond to the specific STA of the above description, and the wireless device 850 of the above description.

STA 100 may include processor 110, memory 120 and transceiver 130 and AP 150 may include processor 160, memory 170 and transceiver 180. [ The transceivers 130 and 180 transmit / receive wireless signals and may be implemented at a physical layer such as IEEE 802.11 / 3GPP. Processors 110 and 160 are implemented in the physical layer and / or MAC layer and are coupled to transceivers 130 and 180. Processors 110 and 160 may perform the UL MU scheduling procedure described above.

Processors 110 and 160 and / or transceivers 130 and 180 may include application specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. The memories 120 and 170 may comprise read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage unit. When an embodiment is executed by software, the method described above may be executed as a module (e.g., process, function) that performs the functions described above. The module may be stored in memory 120,170 and executed by processor 110,160. The memory 120, 170 may be located inside or outside the process 110, 160 and may be coupled to the process 110, 160 by well known means.

The transceiver 130 of the STA may include a transmitter (not shown) and a receiver (not shown). The receiver of the STA may include a main attached radio receiver for receiving a main attached radio (e.g., a wireless LAN such as IEEE 802.11 a / b / g / n / ac / ax) and a WUR receiver for receiving a WUR signal have. The STA's transmitter may include a main connected radio transmitter for transmitting the main connected radio signal.

The transceiver 180 of the AP may include a transmitter (not shown) and a receiver (not shown). The transmitter of the AP may correspond to the OFDM transmitter. The AP may reuse the OFDM transmitter to transmit the WUR payload in an OOK manner. For example, the AP may OOK modulate the WUR payload via an OFDM transmitter, as described above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the present invention has been presented for those skilled in the art to make and use the invention. While the foregoing is directed to preferred embodiments of the present invention, those skilled in the art will appreciate that various modifications and changes may be made by those skilled in the art from the foregoing description. Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The present invention can be applied to various wireless communication systems including IEEE 802.11.

Claims (14)

1. A method for an access point (AP) transmitting a wake up radio (WUR) frame in a wireless local area network (WLAN) system,

   Determining a WUR ID (WID) to be included in a MAC header of a WUR frame for broadcast wake-up; And

   And transmitting the WUR frame including the determined WID,

   The AP determines whether the purpose of the broadcast wake-up is to receive a broadcast data frame on a primary connectivity radio (PCR) to the STA, Wherein the WID is determined based on whether the WID is a second purpose for instructing the WID to perform.
2. The method according to claim 1,

   The AP sets a first one of the entire WID areas as an individual STA ID area and a second range as a GID area,

   Wherein the WID to be included in a MAC header of a WUR frame for the broadcast wakeup is determined within the GID region.
3. The method according to claim 1,

   If the purpose of the broadcast wake-up is a first purpose to instruct the BSS parameter update, the WID is determined as a first special value,

   Wherein the WID is determined as a second special value if the second purpose is to indicate that the purpose of the broadcast wake-up is to receive a broadcast data frame on the PCR.
4. The method of claim 3,

   Wherein the first special value and the second special value are not assigned to an individual STA ID or group ID (GID).
5. The method of claim 3,

   Wherein the WID is determined as a third special value when the purpose of the broadcast wake-up includes both the first and second purposes.
6. 6. The method of claim 5,

   The first special value is 0 or a partial BSSID,

   The second special value is 1 or a partial BSSID +1,

   Wherein the third special value is 2 or a partial BSSID + 2.
7. A method for receiving a wake up radio (WUR) frame from a station (STA) in a wireless local area network (WLAN) system,

   Receiving a WUR frame for broadcast wake-up;

   Obtaining a WUR ID (WID) included in a MAC header of the WUR frame; And

   Based on the obtained WID, whether the purpose of the broadcast wake-up is a first purpose for updating a basic service set (BSS) parameter or a second purpose for receiving a broadcast data frame on a primary connectivity radio (PCR) / RTI >
8. 8. The method of claim 7,

   A first one of the entire WID areas is set as an individual STA ID area, a second one is set as a group ID (GID) area,

   Wherein the WID contained in the MAC header of the WUR frame for the broadcast wake-up is determined in the GID region.
9. 8. The method of claim 7,

   If the WID is a first special value, the STA determines that the purpose of the broadcast wakeup is a first purpose for instructing the BSS parameter update,

   If the WID is a second special value, the STA determines that the purpose of the broadcast wake-up is a second purpose for indicating to receive a broadcast data frame on the PCR.
10. The method of claim 3,

    And if the WID is a third special value, the STA determines that the purpose of the broadcast wake-up includes both the first and second purposes.
11. 11. The method of claim 10,

    The first special value is 0 or a partial BSSID,

    The second special value is 1 or a partial BSSID +1,

    Wherein the third special value is 2 or a partial BSSID + 2.
12. 8. The method of claim 7,

    Wherein if the purpose of the broadcast wake-up is determined to be a primary purpose for updating the BSS parameter, the STA receives the beacon frame on the PCR and updates the BSS parameter based on the received beacon frame.
13. 8. The method of claim 7,

    Wherein if the purpose of the broadcast wake-up is determined to be a second purpose for receiving a broadcast data frame on the PCR, the STA returns to the WUR mode after receiving the broadcast data frame.
14. An access point (AP) for transmitting a WUR (wake up radio) frame,

    A processor for determining a WUR ID (WID) to be included in a MAC header of a WUR frame for broadcast wakeup; And

    And a transmitter for transmitting the WUR frame including the determined WID,

    The processor is further configured to determine whether the purpose of the broadcast wake-up is a first purpose for instructing a STA to update a basic service set (BSS) parameter or to receive a broadcast data frame on a primary connectivity radio (PCR) Wherein the WID is determined based on whether the WID is a second purpose for instructing to perform the WID.

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