WO2019045438A1 - Method for performing fst in wireless lan system, method for supporting fst, and device therefor - Google Patents

Abstract

The present specification presents a method for performing fast session transfer (FST) in a wireless LAN (WLAN) system, a method for supporting the FST, and a device therefor. An embodiment applicable to the present invention explains in detail about specific methods for, in performing/supporting FST from a first band to a second band, performing/supporting the FST if the second band is operating in hidden mode, and about a device therefor.

Description

A method of performing FST in a wireless LAN system, a method of supporting FST, and a device therefor

The following description relates to a method for performing Fast Session Transfer (FST) in a wireless LAN (WLAN) system, a method for supporting the FST, and an apparatus therefor.

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 and supports a maximum speed of 1 Gbit / s, has been discussed in the IEEE 802.11ax standard.

The present invention proposes a method for supporting FST, a method for performing FST beamforming on the basis of the method, and an apparatus therefor.

According to an aspect of the present invention, there is provided a method of performing Fast Session Transfer (FST) in a first station (STA) capable of operating in a first band and a second band in a wireless LAN (WLAN) Receiving an FST setup request frame from the second STA requesting FST setup from the first band to the second band; And performing an association procedure in the second band after the FST including the reception of the FST setup request frame, wherein the FST setup request frame is generated in a mode in which the second band operates in a hidden mode Wherein the FST setup request frame further includes a service set identifier (SSID) for the second band if the second band operates in a hidden mode, And the association procedure in the second band is performed based on the SSID of the second band included in the FST setup request frame when the second band operates in the hidden mode.

The FST method may further include, in response to the FST setup response frame, the first STA transmitting an FST setup response frame to the second STA.

At this time, the FST setup request frame and the FST setup response frame may be transmitted through the first band.

The FST method may further include receiving an FST ACK request frame requesting the second STA to confirm the FST performance; And, in response to the FST ACK request frame, the first STA transmitting an FST ACK response frame to the second STA.

At this time, the FST ACK request frame and the FST ACK response frame may be transmitted through the second band.

Information indicating whether the second band operates in the hidden mode may be transmitted in a multi-band element included in the FST setup request frame.

At this time, the information indicating whether the second band operates in the hidden mode is included in a multi-band control field or a multi-band connection capability field included in the multi- Lt; / RTI >

If the second band operates in the hidden mode, the SSID for the second band may be included in the FST Setup Request frame Action field in the FST setup request frame.

The association procedure in the second band performed based on the SSID for the second band when the second band operates in the hidden mode is performed by the first STA in the second band included in the FST setup request frame, And transmitting the probe request frame including the SSID to the probe request frame.

The first band may correspond to one of the 2.4 GHz band, the 5 GHz band, and the 6 GHz band.

At this time, the second band may correspond to one band different from the first band among the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the 60 GHz band.

In the present invention, the target STA in which the first STA performs the association procedure in the second band may be a STA different from the second STA.

According to another aspect of the present invention for solving the above problems, there is provided a method of transmitting a FST (Fast Session Transfer) message of a second STA that a first station (STA) can operate in a first band and a second band in a wireless LAN (WLAN) The method comprising: transmitting an FST setup request frame requesting FST setup to the second band from the first band to the second STA, Wherein the FST setup request frame includes information indicating whether to operate in a hidden mode, and when the second band operates in a hidden mode, the FST setup request frame includes a service set identifier (SSID) The method of claim 1, further comprising:

According to another aspect of the present invention, there is provided a station apparatus capable of operating in a first band and a second band in a wireless local area network (WLAN) system and performing FST (Fast Session Transfer) A transceiver configured to transmit and receive signals with one or more other station devices having the above-described RF (Radio Frequency) chain; And a processor coupled to the transceiver for processing signals transmitted to and received from the one or more other station devices, wherein the processor is configured to request the second STA to configure the FST from the first band to the second band, Receive an FST setup request frame; And an association procedure in the second band after FST including reception of the FST setup request frame, wherein the FST setup request frame is configured to determine whether the second band operates in a hidden mode Wherein if the second band operates in a hidden mode, the FST setup request frame further includes a service set identifier (SSID) for the second band, 2 band operates in the hidden mode, the association procedure in the second band is performed based on the SSID for the second band included in the FST setup request frame.

According to still another aspect of the present invention, there is provided a method of transmitting data to a station supporting a fast session transfer (FST) to a first station device operable in a first band and a second band in a wireless local area network (WLAN) An apparatus comprising: a transceiver having one or more RF (Radio Frequency) chains and configured to transmit and receive signals with one or more other station devices; And a processor coupled to the transceiver for processing signals transmitted to and received from the one or more other station devices, wherein the processor is operable to transmit the FST settings from the first band to the second band to the first station device Wherein the FST setup request frame includes information indicating whether the second band operates in a hidden mode and the second band operates in a hidden mode, , The FST setup request frame further includes a service set identifier (SSID) for the second band.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

Through the above-described configuration, the initiator and the responder according to the present invention can support (or perform) FST without delay in the medium access procedure in a specific band operating in a hidden mode.

In particular, even if the 60 GHz band operates in the hidden mode, the STA can know the SSID of the switched 60 GHz band in advance according to the FST operation, thereby reducing unnecessary power consumption and seek time.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention, illustrate various embodiments of the invention and, together with the description, serve to explain the principles of the 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 views for explaining the operation of the STA receiving the TIM in detail.

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

11 is a view for explaining a channel in a 60 GHz band for explaining a channel bonding operation according to an embodiment of the present invention.

12 is a view for explaining a basic method of performing channel bonding in a wireless LAN system.

13 is a diagram for explaining the configuration of the beacon interval.

14 is a diagram for explaining a physical configuration of an existing radio frame.

FIGS. 15 and 16 are diagrams for explaining the configuration of a header field of the radio frame of FIG.

17 is a diagram showing a PPDU structure applicable to the present invention.

18 is a view schematically showing a PPDU structure applicable to the present invention.

19 shows an example of a beamforming training process applicable to the present invention.

Figures 20 and 21 are illustrations of examples of SLS steps.

22 is a view briefly showing a MIMO step for SU-MIMO applicable to the present invention.

23 is a view briefly showing a downlink MIMO step applicable to the present invention.

24 is a view briefly showing an uplink MIMO step applicable to the present invention.

25 is a diagram showing a multi-band element applicable to the present invention.

26 is a diagram schematically showing a format of a multi-band control field applicable to the present invention.

Figure 27 is a simplified representation of the format of the multi-band connection capability field applicable to the present invention.

28 is a diagram briefly showing an operation of supporting / performing FST of STA in a wireless LAN system applicable to the present invention.

29 is a diagram showing an SSID element format applicable to the present invention.

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

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.

The mobile communication system to which the present invention is applied may be various. Hereinafter, a wireless LAN system will be described in detail as an example of a mobile communication system.

One. Wireless LAN (Wireless LAN, WLAN ) system

1-1. Wireless LAN System General

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.

The STA is a logical entity including a medium access control (MAC) and a physical layer interface for 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 personal basic service set central point / access point (PCP / AP)

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). STAs included in an ESS can communicate with each other, and in the same ESS, a 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.

1-2. 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 specific 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 via PLME_SAP and exchanged between MLME and PLME through MLME-PLME_SAP.

1-3. Link Setup 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 in channel 1 and receives the probe response frame in 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 in step S540 may be referred to as an authentication process through a Robust Security Network Association (RSNA) request / response. The authentication process in 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.

1-4. 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, a random 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 the case of a transmission failure (for example, in the case of not receiving an ACK for a transmitted frame). If the CW parameter value is CWmax, the data transmission can be attempted while maintaining the CWmax value until the data transmission is successful. If the data transmission is successful, the CWmin value is reset to the CWmin value. CW, CWmin and CWmax are preferably set to 2n-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 in an idle state 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, if the medium becomes idle, it can wait for DIFS, count down according to an arbitrary backoff count value selected by the STA4, and start 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.

1-5. STA sensing behavior

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.

1-6. 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 for as long as possible, power consumption is reduced, which increases the operating time of the STA. 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.

1-7. 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.

In addition, a specific configuration in a wireless LAN system supporting the 60 GHz band such as IEEE 802.11ad and 802.11ay, to which the present invention is applicable, will be described in detail below. Hereinafter, the following WLAN system is merely an example of a system to which the operation configuration suggested by the present invention can be applied, and the operation configuration proposed by the present invention can be similarly applied to other systems other than the following WLAN system.

2. Wireless LAN systems supporting 60 GHz band (eg IEEE 802.11ad, IEEE 802.11ay, etc.)

2-1. Channel bonding in wireless LAN systems

11 is a view for explaining a channel in a 60 GHz band for explaining a channel bonding operation according to an embodiment of the present invention.

As shown in FIG. 11, four channels can be configured in the 60 GHz band, and the general channel bandwidth can be 2.16 GHz. Available ISM bands (57 GHz to 66 GHz) available at 60 GHz may be specified differently in different countries. In general, channel 2 of the channel shown in FIG. 11 is available in all regions and can be used as a default channel. Most of the points, except Australia, use channel 2 and channel 3, which can be used for channel bonding. However, the channel used for channel bonding may vary, and the present invention is not limited to a specific channel.

12 is a view for explaining a basic method of performing channel bonding in a wireless LAN system.

The example of FIG. 12 illustrates an example of combining two 20 MHz channels in an IEEE 802.11n system to operate with 40 MHz channel bonding. For IEEE 802.11ac systems, 40/80/160 MHz channel bonding will be possible.

The exemplary two channels in FIG. 12 include a Primary Channel and a Secondary Channel, and the STA can review the channel status in the CSMA / CA manner for the main channel among the two channels. If the auxiliary channel is idle for a predetermined time (e.g., PIFS) at a time when the main channel idle during a constant backoff interval and the backoff count becomes zero, A secondary channel can be combined to transmit data.

However, as described above, when channel-bonding is performed based on contention as shown in FIG. 12, channel bonding can be performed only when the auxiliary channel remains idle for a predetermined time at the time when the backoff count for the main channel expires Therefore, the application of the channel bonding is very limited, and it is difficult to flexibly cope with the media situation.

Accordingly, an aspect of the present invention proposes a method of performing scheduling based access by transmitting AP scheduling information to STAs. Meanwhile, another aspect of the present invention proposes a method of performing channel access based on the above-described scheduling or on a contention-based basis independently of the above-described scheduling. According to another aspect of the present invention, there is provided a method of performing communication through a spatial sharing method based on beamforming.

2-2. Configuring Beacon Spacing

13 is a diagram for explaining the configuration of the beacon interval.

In 11ad-based DMG BSS systems, the time of media can be divided by beacon intervals. The sub-intervals within the beacon interval may be referred to as Access Periods. Different connection intervals within one beacon interval may have different connection rules. The information on the connection interval may be transmitted to the non-AP STA or the non-PCP by an AP or a Personal Basic Service Set Control Point (PCP).

As shown in FIG. 13, one beacon interval may include one BHI (Beacon Header Interval) and one DTI (Data Transfer Interval). The BHI may include a Beacon Transmission Interval (BTI), an Association Beamforming Training (A-BFT), and an Announcement Transmission Interval (ATI) as shown in FIG.

BTI refers to the interval over which one or more DMG beacon frames can be transmitted. A-BFT denotes a period during which the beamforming training performed by the STA that transmitted the DMG beacon frame during the preceding BTI is performed. ATI means a request-response based management access interval between a PCP / AP and a non-PCP / non-AP STA.

Meanwhile, a DTI (Data Transfer Interval) is a period in which frames are exchanged between STAs, and one or more Contention Based Access Period (CBAP) and one or more service period (SP) can be allocated as shown in FIG. In FIG. 13, two CBAPs and two SPs are allocated. However, the present invention is not limited thereto.

Hereinafter, the physical layer configuration in the wireless LAN system to which the present invention is applied will be described in detail.

2-3. Physical Layer Configuration

It is assumed that the following three different modulation modes can be provided in the wireless LAN system according to an embodiment of the present invention.

PHY	MCS	Note
Control PHY	0
Single carrier PHY (SC PHY)	1, ..., 1225, ..., 31	(low power SC PHY)
OFDM PHY	13, ..., 24

Such modulation modes can be used to satisfy different requirements (e.g., high throughput or stability). Depending on the system, some of these modes may be supported.

14 is a diagram for explaining a physical configuration of an existing radio frame.

It is assumed that all the DMG physical layer layers commonly include fields as shown in Fig. However, there may be a difference between the prescribed scheme of the individual fields and the modulation / coding scheme used depending on each mode.

As shown in FIG. 14, the preamble of the radio frame may include STF (Short Training Field) and CE (Channel Estimation). In addition, the radio frame may include a header and a data field as payload and a TRN (Training) field for beamforming selectively.

FIGS. 15 and 16 are diagrams for explaining the configuration of a header field of the radio frame of FIG.

Specifically, FIG. 15 shows a case where an SC (Single Carrier) mode is used. In the SC mode, the header includes information indicating an initial value of scrambling, a modulation and coding scheme (MCS), information indicating the length of data, information indicating whether there is an additional physical protocol data unit (PPDU), packet type, training length, Whether it is a beam training request, a last Received Signal Strength Indicator (RSSI), truncation, and HCS (Header Check Sequence). Also, as shown in FIG. 15, the header has 4 bits of reserved bits, and the reserved bits may be utilized in the following description.

16 shows a specific structure of a header when the OFDM mode is applied. The OFDM header includes information indicating an initial value of scrambling, information indicating the length of data, information indicating whether there is an additional PPDU, packet type, training length, aggregation status, beam training request status, last RSSI, (Header Check Sequence), and the like. In addition, as shown in FIG. 16, the header has 2 bits of reserved bits. In the following description, such reserved bits may be used as in the case of FIG.

As described above, the IEEE 802.11ay system is considering the introduction of channel bonding and MIMO technology for the first time in the existing 11ad system. In order to realize channel bonding and MIMO in 11ay, a new PPDU structure is needed. In other words, existing 11ad PPDU structure has limitations in supporting legacy terminals and implementing channel bonding and MIMO.

For this, a legacy preamble for supporting the legacy terminal, a new field for the terminal 11ay after the legacy header field can be defined, and channel bonding and MIMO can be supported through the newly defined field.

17 is a diagram showing a PPDU structure according to a preferred embodiment of the present invention. In Fig. 17, the abscissa axis corresponds to the time domain, and the ordinate axis corresponds to the frequency domain.

When two or more channels are bonded, a frequency band (for example, a 400 MHz band) may exist in a frequency band (e.g., 1.83 GHz) used in each channel. In the mixed mode, a legacy preamble (legacy STF, legacy CE) is transmitted in duplicate through each channel. In an embodiment of the present invention, a new STF and a CE Gap filling of the field may be considered.

In this case, as shown in FIG. 17, the PPDU structure according to the present invention transmits ay STF, ay CE, ay header B, payload in a wide band after the legacy preamble, legacy header and ay header A . Accordingly, the ay header, the ay Payload field, etc. transmitted after the header field can be transmitted through the channels used for the bonding. In order to distinguish the ay header from the legacy header, an enhanced directional multi-gigabit (EDMG) header may be used. The corresponding names may be used in combination.

For example, a total of six or eight channels (2.16 GHz each) may exist in 11ay, and a maximum of four channels can be transmitted as a single STA. Thus, the ay header and ay payload can be transmitted over 2.16GHz, 4.32GHz, 6.48GHz, and 8.64GHz bandwidths.

Alternatively, the PPDU format when the legacy preamble is repeatedly transmitted without performing the gap-filling as described above may be considered.

In this case, without performing Gap-Filling, the month STF, ay CE, and ay header B without the GF-STF and GF-CE fields shown by the dashed line in FIG. 16 are set as broadband after the legacy preamble, legacy header, Transmission.

18 is a view schematically showing a PPDU structure applicable to the present invention. The PPDU format described above can be summarized as shown in FIG. 18

18, the PPDU format applicable to the 11-ay system includes L-STF, L-CE, L-Header, EDMG-Header-A, EDMG-STF, EDMG-CEF, EDMG- TRN field, which may optionally be included according to the type of PPDU (e.g., SU PPDU, MU PPDU, etc.).

Here, the portion including the L-STF, L-CE, and L-header fields can be called a non-EDMG region and the remaining portion can be called an EDMG region. The L-STF, L-CE, L-Header, and EDMG-Header-A fields may be referred to as pre-EDMG modulated fields and the rest may be referred to as EDMG modulated fields.

The (legacy) preamble portion of the PPDU as described above is used for packet detection, automatic gain control (AGC), frequency offset estimation, synchronization, modulation (SC or OFDM) can be used for channel estimation. The format of the preamble may be common to OFDM packets and SC packets. At this time, the preamble may be composed of STF (Short Training Field) and CE (Channel Estimation) field located after the STF field. (The preamble is the part of the PPDU that is used for packet detection, AGC, frequency offset estimation, synchronization, indication of modulation (SC or OFDM) and channel estimation. . The preamble is composed of two parts: the Short Training field and the Channel Estimation field.

2-4. The beam forming procedure applicable to the present invention

As described above, in the 11ay system to which the present invention can be applied, channel bonding, channel aggregation, and FDMA, which transmit data using a plurality of channels simultaneously, can be applied. Particularly, in the 11ay system to which the present invention is applicable, a signal in a high frequency band is utilized, and a beam forming operation can be applied to transmit and receive a signal with high reliability.

However, in the conventional 11ad system, only the beam forming method for one channel is disclosed, but the beam forming method applicable to a plurality of channels is not suggested at all. Accordingly, in the present invention, a beam forming procedure for channel bonding or channel aggregation transmission using a plurality of channels will be described in detail.

The beamforming training procedure for one channel will be described in detail in order to explain the beamforming procedure applicable to the present invention.

19 shows an example of a beamforming training process applicable to the present invention.

Basically, the beamforming procedure applicable to the present invention can be largely composed of a SLS (Sector Level Sweep) phase and a BRP (Beam Refinement Protocol or Beam Refinement Phase) phase. At this time, the BRP step may be selectively performed.

Hereinafter, an STA that wants to transmit data through a beamforming operation is called an initiator, and a STA that receives data from the initiator is called a responder.

For BF training occurring within the Association Beamforming Training (A-BFT) assignment, the AP or PCP / AP is the initiator and the non-AP and non-PCP / AP STAs are the responders. In BF training occurring within an SP assignment, the source (EDMG) STA of the SP is the initiator and the destination STA of the SP becomes the responder. TXOP (Transmission Opportunity) Allocation In BF training, the TXOP holder is the initiator and the TXOP responder becomes the responder.

The link from the initiator to the responder is called an initiator link and the link from the responder to the initiator is called a responder link.

In the 60 GHz band supported by the 11ay system to which the present invention is applicable, a directional transmission scheme other than an omni transmission scheme can be applied to more reliably transmit data and control information.

As a process for this, STAs that want to transmit / receive data can know the TX or RX best sector for the initiator and the responder through the SLS process.

This BF training begins with a sector level sweep (SLS) from the initiator. The purpose of the SLS step is to enable communication between two STAs at the control PHY rate or higher MCS. In particular, the SLS step only provides for transmitting BF training.

Additionally, the SLS may be followed by a BRP (Beam Refinement Protocol or Beam Refinement Phase) if there is an initiator or responder request.

The purpose of the BRP phase is to enable receive training and enable iterative refinement of the AWV (Antenna Weight Vector) of all transmitters and receivers in all STAs. If one of the STAs participating in beam training chooses to use only one transmit antenna pattern, the receive training may be performed as part of the SLS step.

More specifically, the SLS step may include the following four elements: Initiator Sector Sweep (ISS) for training the initiator link, Responder Sector Sweep (RSS) for training the responder link, , SSW feedback, SSW ACK.

The initiator initiates the SLS phase by transmitting the frame (s) of the ISS.

The responder does not begin transmitting the frame (s) of the RSS before the ISS has successfully completed. However, this may be an exception if the ISS occurs within the BTI.

The initiator does not initiate SSW feedback before the RSS phase is successfully completed. However, it may be an exception if the RSS occurs in the A-BFT. The responder does not start the initiator's SSW ACK in the A-BFT.

The responder immediately starts the initiator's SSW ACK after successful completion of the initiator's SSW feedback.

The BF frame transmitted by the initiator during the SLS phase may include (EDMG) beacon frame, SSW frame, and SSW feedback frame. During the SLS step, the BF frame transmitted by the responder may include an SSW frame and an SSW-ACK frame.

At the end of the SLS phase, the initiator and responder each possess their own transport sector if the initiator and responder each perform a TXS (Transmit Sector Sweep) during the SLS. If an ISS or RSS employs a receive sector sweep, each responder or initiator will have their own receiving sector.

The STA does not change the transmit power during the sector sweep.

Figures 20 and 21 are illustrations of examples of SLS steps.

In Fig. 20, the initiator has many sectors, and the responder has one transmit sector and one receive sector used in RSS. Thus, the responder transmits all responder SSW frames on the same transmission sector, while the initiator switches the receive antennas.

In Fig. 21, the initiator has many transmission sectors, and the responder has one transmission sector. In this case, receive training for the initiator may be performed in the BRP step.

Such an SLS can be summarized as follows.

SLS is a protocol for performing link detection in an 802.11ay system to which the present invention is applicable, in which network nodes continuously transmit and receive frames containing the same information while changing only the beam direction, (E.g., Signal to Ratio (SNR), Received Signal Strength Indicator (RSSI), and the like) indicative of the performance of the receiving channel link.

Next, the BRP can be summarized as follows.

The BRP is a protocol for fine-tuning the beam direction that can maximize the data rate in the beam direction determined by SLS or other means, and can be performed as needed. This BRP performs beam training using a BRP frame, which is defined for the BRP protocol, which includes beam training information and information reporting the training results. For example, the BRP transmits and receives BRP frames using beams determined by previous beam training and substantially performs beam training using a beam training sequence included at the end of the successfully transmitted and received BRP frames Beam training method. SLS uses the frame itself for beam training, but BRP can be different in that it only uses the beam training sequence.

This SLS step may be performed within a Beacon Header Interval (BHI) and / or a Data Transfer Interval (DTI).

First, the SLS step performed during the BHI may be the same as the SLS step defined in the 11ad system for coexistence with the 11ad system.

Then, the SLS step performed during the DTI can be performed when the beamforming training between the initiator and the responder is not performed or the beamforming link (BF link) is lost. At this time, if the initiator and the responder are 11ay STAs, the initiator and the responder can send a short SSW (Short SSW) frame instead of the SSW frame for the SLS step.

Here, the short SSW (short SSW) frame may be defined as a frame including a short SSW packet in the data field of the DMG control PHY or the DMG control mode PPDU. At this time, the specific format of the short SSW packet may be set differently according to the purpose (e.g., I-TXSS, R-TXSS, etc.) in which the short SSW packet is transmitted.

In addition, the beamforming protocol for SU-MIMO or MU-MIMO may be composed of a SISO phase (SISO phase) and a MIMO phase (MIMO phase).

At this time, the SISO step may be optionally applied to select candidates for beamforming training in the MIMO step. Therefore, the description of the operation in the SISO step is omitted in the present invention.

In the MIMO step, initiators and responders perform training of the transmitting and receiving sector and the DMG antenna to determine the optimal combination of transmitting and receiving sectors and antennas for MIMO transmission. In particular, in the case of MU-MIMO, at the MIMO step, each initiator and each responder in the MU group performs training of the transmitting and receiving sector and the DMG antenna to determine the optimal combination of transmitting and receiving sectors and antennas for MIMO transmission.

22 is a view briefly showing a MIMO step for SU-MIMO applicable to the present invention. As shown in FIG. 22, the MIMO step for SU-MIMO may be composed of the following four sub-steps: SU-MIMO BF setup subphase, initiator SU-MIMO BF MIMO BF feedback subphase, responder SMBT subphase, and SU-MIMO BF feedback sub-step.

In the SU-MIMO BF setup step, the initiator may send a MIMO BF setup frame with the SU / MU field set to 1 and the Link Type field set to 1 to the responder. In particular, in the case of channel combining, the initiator may send a MIMO BF setup frame with the 'Aggregation Requested' field set to 1 to the responder. The 'TA (Transmitter Address)' field and the 'RA (Receiver Address)' field of the MIMO BF setting frame may be set to the Medium Access Control (MAC) address of the initiator and the responder, respectively. (In the SU-MIMO BF setup subphase, the initiator shall send a MIMO BF Setup frame with the SU / MU field set to 1 and the Link Type field set to 1 to the responder. BF Setup frame with the Aggregation Requested field set to 1 responder. The TA field and the RA field of the MIMO BF setup frame shall be set to the MAC addresses of the initiator and the responder, respectively.

The responder can transmit a MIMO BF setting frame in which the 'SU / MU' field is set to '1' and the 'Link Type' field is set to '0' after SIFS from the time when the MIMO BF setting frame is received from the initiator. In particular, for channel combining, the responder may send a MIMO BF setup frame with the 'Aggregation Requested' field set to 1 to the initiator. (The responder shall send a MIMO BF Setup frame with the SU / MU field set to 1 and the Link Type field set to 0 a SIFS following the reception of the MIMO BF Setup frame from the initiator. a MIMO BF Setup frame with the Aggregation Requested field set to 1 initiator.

The initiator may then initiate the initiator SMBT sub-step after MBIFS from the time the MIMO BF setup frame is received from the responder. In the initiator SMBT sub-step, the initiator may send an EDMG BRP-RX / TX packet (including a TRN field) to the responder. In particular, for channel combining, the EDMG BRP-RX / TX packet may be transmitted using a non-EDMG replication format. At this time, each EDMG BRP-RX / TX packet to be transmitted can be divided into SIFS intervals. (The initiator shall initiate the initiator SMBT subphase a MBIFS following reception of the MIMO BF setup frame from the responder. In the initiator SMBT subphase, the initiator shall transmit EDMG BRP-RX / TX packets to the responder In channel aggregation, the EDMG BRP-RX / TX packets shall be transmitted by the non-EDMG duplicate format. Each EDMG BRP-RX / TX packet shall be separated by SIFS.

At this time, each transmitted EDMG BRP-RX / TX packet is used to train one or more transmission sectors and a certain number of reception AWVs (for each transmission sector). For each EDMG BRP-RX / TX packet, the initiator (for each selected transport sector) may include in the PPDU a TRN field for the responder to perform receive AWV training. (Each transmitted EDMG BRP-RX / TX packet is used to train one or more transmit sectors, and each transmit sector receives a number of receive AWVs. transmit sector, TRN subfields in the TRN field of the PPDU for the responder to receive AWV training.

The responder can then start the responder SMBT sub-step after MBIFS from the receipt of the EDMG BRP-RX / TX packet with the 'BRP CDOWN' field set to 0 from the initiator. In the respondent SMVT sub-step, the responder may send an EDMG BRP-RX / TX packet (including the TRN field) to the responder. In particular, for channel combining, the EDMG BRP-RX / TX packet may be transmitted using a non-EDMG replication format. At this time, each EDMG BRP-RX / TX packet to be transmitted can be divided into SIFS intervals. (The responder shall initiate the responder SMBT subphase a MBIFS following the reception of an EDMG BRP-RX / TX packet with the BRP CDX field set to 0 from the initiator. In the responder SMBT subphase, the responder shall transmit EDMG BRP-RX / Each EDMG BRP-RX / TX packet shall be transmitted by a non-EDMG duplicate format. Each EDMG BRP-RX / TX packet shall be separated by SIFS.

The initiator may then initiate the SU-MIMO BF feedback step after MBIFS from the time of receipt of the EDMG BRP-RX / TX packet with the 'BRP CDOWN' field set to 0 from the responder. All frames transmitted in the SU-MIMO BF feedback section may be transmitted using the DMG control mode. In the SU-MIMO BF feedback step, the initiator may transmit a MIMO BF feedback frame with a 'SU / MU' field set to '1' and a 'Link Type' field set to '0' to a responder. In particular, for channel combining, the initiator may send a MIMO BF feedback frame with the 'Aggregation Present' field set to 1 to the responder. The TA field of the MIMO BF feedback frame may be set to the MAC address of the initiator and the RA field may be set to the MAC address of the responder. (The initiator shall initiate the SU-MIMO BF feedback subphase a MBIFS following reception of an EDMG BRP-RX / TX packet with the BRP CDOWN field set to 0 from the responder. MIMO BF feedback sub-frame, the initiator shall send to the responder a MIMO BF feedback frame with the SU / MU field set to 1 and the link type field set to 0. In channel aggregation, the MIMO BF feedback frame shall be set to the initiator and the RA field shall be set to the MAC address of the MIMO BF feedback frame. address of the responder.

The responder can transmit a MIMO BF feedback frame in which the 'SU / MU' field is set to '1' and the 'Link Type' field is set to '1' after SIFS from the reception of the MIMO BF feedback frame from the initiator. In particular, in the case of channel combining, the responder may send a MIMO BF feedback frame with the 'Aggregation Present' field set to 1 to the initiator. The TA field of the MIMO BF feedback frame may be set to the MAC address of the responder and the RA field may be set to the MAC address of the initiator. MIMO BF Feedback frame to the initiator with the SU / MU field set to 1 and the MIMO BF feedback frame from the initiator. In channel aggregation, the responder The MIMO BF feedback shall be set to the initiator. The MIMO BF feedback shall be set to the MAC address of the responder and the RA field shall be set to the MAC address of the MIMO BF feedback frame. initiator.)

In addition, the MIMO step for MU-MIMO may comprise a downlink MIMO phase (uplink MIMO phase) and an uplink MIMO phase (uplink MIMO phase).

23 is a view briefly showing a downlink MIMO step applicable to the present invention.

23, the downlink MIMO step may be composed of the following four sub-steps: an MU-MIMO BF setting sub-step MU-MIMO BF training sub-step MU- training subphase, an MU-MIMO BF feedback sub-phase, and an MU-MIMO BF selection sub-phase.

Herein, the MU-MIMO BF training section and the MU-MIMO BF feedback section may not exist in the MIMO stage according to the condition.

In the MU-MIMO BF setting step, the initiator may send one or more MIMO BF setup frames with the 'SU / MU' field set to 0 and the 'DL / UL MIMO Phase' field set to 1 to each responder in the MU group . In particular, in the case of channel combining, the initiator may send one or more MIMO BF setup frames with the 'Aggregation Requested' field set to 1 to each responder in the MU group. The initiator may send a minimum MIMO BF setup frame that can reach all responders in the MU group. (In the MU-MIMO BF setup subphase, the initiator shall transmit one or more MIMO BF Setup frame with the SU / MU field set to 0 and the UL / UL MIMO Phase field set to 1 to each responder in the MU group. The MIMO BF setup frame is used to transmit the minimum number of MIMO BF frames to reach the MU group. .)

The MIMO BF setup frame may be transmitted using a non-EDMG replicated PPDU that is transmitted with a DMG control mode or a DMG control modulation class. (The MIMO BF Setup frames should be sent using the DMG control mode or a non-EDMG duplicate PPDU transmitted with the DMG control modulation class.)

The TA (Transmitter Address) field of the MIMO BF setup frame is set to the BSSID of the initiator, and the RA field of the MIMO BF setup frame is set to a broadcast address.

The MIMO BF setup frame indicates an EDMG Group ID in the MU group in the EDMG Group IP field, a remaining responder in the Group User Mask field, and a special dialog token in the Dialog Token field to identify the MU-MIMO BF training The MIMO BF Setup frame shall indicate the EDMG group ID of the EDMG Group ID field, each remaining responder in the Group User Mask field, and a unique dialog token in the Dialog Token field for identifying MU-MIMO BF training).

In order to reduce the MU-MIMO BF training time, the initiator initiates the transmission of the TX sectors for each DMG antenna based on the L-TX-RX subfields and the EDMG TRN-Unit M subfields in the feedback received from the responders in the SISO phase The number of TRN subfields required for reception of subset and AWV training can be selected (To reduce the MU-MIMO BF training time, the initiator may select a subset of TX sectors for each DMG antenna and the number of TRN subfields required for receive AWV training based on L-TX-RX subfields and the EDMG TRN-Unit M subfields in the feedback from responders received at the SISO phase.

A responder whose corresponding bit in the Group User Mask field of the received MIMO BF setup frame is set to 0 may ignore frames transmitted in the subsequent MU-MIMO BF training section and MU-MIMO BF feedback section MIMO BF training subphase and MU-MIMO BF feedback subphase) are transmitted in the following order.

The initiator may initiate the MU-MIMO BF training sub-step after MBIFS from the transmission time of the MIMO BF setup frame. In the MU-MIMO BF training phase, the initiator may send one or more EDMG BRP / RX / TX packets to the remaining responders in the MU group. In particular, for channel combining, each EDMG BRP-RX / TX packet may be transmitted using a non-EDMG replication format. Each EDMG BRP-RX / TX packet can be distinguished by SIIFS. (The initiator shall initiate the MU-MIMO BF training subphase a MBIFS following the transmission of the MIMO BF setup frame. In the MU-MIMO BF training subphase, the initiator shall transmit one or more EDMG BRP-RX / TX packets to the remaining Each EDMG BRP-RX / TX packet shall be transmitted by the non-EDMG duplicate format. Each EDMG BRP-RX / TX packet shall be separated by SIFS.

In particular, in the MU-MIMO BF training phase, the initiator transmits BRP frames using the EDMG PHY layer (In the MU-MIMO BF training subphase, the initiator will transmit BRP frames using the EDMG PHY). Each transmitted BRP frame is used to train one or more transmit sectors and a certain number of receive AWVs for each transmit sector (Each transmitted BRP frame is used to train one or more transmit sectors, number of receive AWVs). The initiator in each BRP frame includes TRN-units in the TRN field for each selected sector so that intended responders can perform the receiving sector training (In each BRP frame for the selected sector, TRN -Units in the TRN field for intended responders to perform sector training).

The number of TRN-Units included in the TRN field shall be the number of the maximum number of received sectors across all the remaining intended responders based on the feedback from the SISO phase (the number of TRN-units included in the TRN field should be the maximum number of receive sectors across all the desired intended recipients based on the feedback from the SISO phase).

The initiator may transmit a BRP frame of orthogonal waveforms to simultaneously train the transmit DMB antennas (up to four) over the same BRP frame, thereby reducing the training time (an initiator may transmit a BRP frame with orthogonal waveforms to train multiple (up to 4) transmit DMG antennas simultaneously through the same BRP frame and thus reduce the training time.

The MU-MIMO BF training phase is performed by setting the TXVECTOR parameter EDMG_TRN_LEN of the BRP frame to a value greater than zero and setting the TXVECTOR parameter RX_TRN_PER_TX_TRN to a value greater than one (The MU-MIMO BF training subphase is performed by setting BRP frame, the TXVECTOR parameter EDMG_TRN_LEN to a value greater than zero and the parameter RX_TRN_PER_TX_TRN to a value greater than one).

The initiator may initiate the MU-MIMO BF feedback phase after MBIFS from the transmission time of the EDMG BRP RX-TX packet with the 'BRP CDOWN' field set to zero. In the MU-MIMO BF feedback step, the initiator sets the 'Poll type' field to 0 for polling to collect MU-MIMO feedback from the previously performed MU-MIMO BF training phase step from each remaining responder And transmit the set MIMO BF Poll frame. The MIMO BF poll frame may be transmitted using the DMG control mode. MIMO BF feedback subphase, the initiator shall transmit a MIMO BF feedback subphase, the initiator shall transmit a MIMO BF feedback subphase, the initiator shall transmit a MIMO BF Poll frame with the Poll Type field set to 0 to poll each remaining responder to collect MU-MIMO BF feedback from the preceding MU-MIMO BF training subphase.

If the remaining responder receives a MIMO BF poll frame with a recipient, the responder may send a MIMO BF feedback frame with the SU / MU field set to 1 to the initiator. In particular, in the case of channel combining, the responder may send a MIMO BF feedback frame with the 'Aggregation Present' field set to 1 to the initiator. The RA field of the MIMO BF feedback frame may be set to a Basic Service Set Identity (BSSID) of the initiator and the TA field may be set to the MAC address of the responder. MIMO BF Feedback frame with the SU / MU field set to 1 initiator. In channel aggregation, the responder shall send a MIMO BF Feedback frame with the Aggregation Present field set to the initiator. The RA field of the MIMO BF Feedback frame shall be set to the BSSID of the initiator and the TA field shall be set to the MAC address of the responder.

Each MIMO BF feedback poll frame and the MIMO BF feedback frame received by the responder are separated by SIFS (Each MIMO BF Feedback Poll frame and MIMO BF Feedback frame sent back by the responder shall be separated by SIFS). Each MIMO BF feedback poll frame carries a dialog token that identifies the MU-MIMO BF training (Each MIMO BF feedback frame carries the token that identifies the MU-MIMO BF training). The MIMO BF feedback frame carries a list of transmitted DMG antennas / sectors of the received initiator, along with the received DMG antenna / sector and associated directed quality of the corresponding responder, respectively (The MIMO BF Feedback frame carries the list of received initiator's transmit DMG antennas / sectors, each with its corresponding responder's receive DMG antenna / sector and the associated quality indicated.

The initiator may initiate the MU-MIMO BF selection step after MBIFS from the time the MIMO BF feedback frame is received from the last remaining responder. In the MU-MIMO selection step, the initiator may transmit one or more MIMO BF selection frames with 'MU-MIMO Transmission Configuration Type' set to 1 to each responder in the MU group. The initiator may send a minimum number of MIMO selection frames to reach all responders in the MU group. The MIMO BF selection frame may be transmitted using the DMG control mode. (The initiator shall initiate the MU-MIMO BF selection subphase an MBIFS following reception of the MIMO BF feedback frame from the last remaining responder. In the MU-MIMO BF selection subphase, the initiator shall transmit one or more MIMO BF Selection frames with the The MIMO BF selection frame is used to transmit the minimum number of MIMO BF selection frames to reach the MU group. mode.)

In the MU-MIMO BF selection step, the initiator sends to each responder in the MU group an MU-MIMO BF training, one or more sets of MU transmission settings, and a dialog token identifying the intended receiving STAs for each MU transmission setting MIMO BF selection frame is transmitted (In the MU-MIMO BF selection sub-phase, the initiator shall transmit a MIMO BF selection frame to each responder in the MU group. the MU transmission configurations, and the intended recipient STAs for each MU transmission configuration.

The last set of selected responders in the MU group included in the MIMO BF selection frame need not be the same as the initial set of intended responders (the MIMO BF selection frame does not have to the same as the initial set of intended responders. The initiator sends a minimum number of MIMO BF selection frames to the selected responders (the initiator should transmit the minimum number of MIMO BF selection frames to selected responders).

24 is a view briefly showing an uplink MIMO step applicable to the present invention.

The uplink MIMO step may reduce the length of the MU-MIMO BF training interval.

The initiator may initiate an uplink MIMO phase procedure if the following condition is satisfied.

- The 'UL MU-MIMO Supported' field in the EDMG Capabilities element of the initiator and the intended recipient is equal to 1,

- If the 'Antenna Patten Reciprocity' field in the initiator's DMG Capabilities element is 1

MIMO BF setup sub-step MU-MIMO BF setup sub-step MU-MIMO BF setup sub-step MU- MIMO BF training subphase, and MU-MIMO selection subphase. Each sub-step is distinguished by MBIFPS.

Here, the MU-MIMO BF training section may not exist in the MIMO stage according to the condition.

In the MU-MIMO BF setting step, the initiator sets one or more MIMO BF setting frames in which the 'SU / MU' field is set to '0' and the 'DL / UL MU-MIMO Phase' Lt; / RTI > In particular, in the case of channel combining, the initiator may send one or more MIMO BF setup frames with the 'Aggregation Requested' field set to 1 to each responder in the MU group. The initiator may send a minimum number of MIMO BF setup frames that can reach all responders in the MU group. (MIMO BF setup subphase, the initiator shall transmit one or more MIMO BF Setup frame with the SU / MU field set to 0 and the UL / UL MU-MIMO Phase field set to 0 to each responder in the MU group In channel aggregation, the initiator shall send one or more MIMO BF Setup frames with the Aggregation Requested field set to 1 to each responder in the MU group. MU group.)

The MIMO BF setup frame may be transmitted using a non-EDMG replicated PPDU that is transmitted with a DMG control mode or a DMG control modulation class. (The MIMO BF Setup frames should be sent using the DMG control mode or using a non-EDMG duplicate PPDU transmitted with the DMG control modulation class.)

The initiator may initiate the MU-MIMO BF training sub-step after MBIFS from the transmission time of the MIMO BF setup frame. In the MU-MIMO BF training step, the initiator may send a MIMO BF poll frame with a 'Poll Type' field set to '1' to each of the remaining responders in the MU group. Each MIMO BF frame may be transmitted using a non-EDMG replicated PPDU that is transmitted with a DMG control mode or a DMG control modulation class. MIMO BF training subphase, MIMO BF training subphase, MIMO BF training subphase, MIMO BF training subphase, MIMO BF training subphase, Each MIMO BF Poll frame should be sent using the DMG control mode or using a non-EDMG duplicate PPDU transmitted with the DMG control modulation class.

When the remaining responder receives a MIMO BF poll frame with a receiver, the TXVECTOR parameter EDMG_TRN_LEN is set to be greater than 0 and the parameters RX_TRN_PER_TX_TRN, EDMG_TRN_M and EDMG_TRN_P are set to the value of the L-TX-RX field and Requested in the corresponding MIMO BF poll frame When the EDMG TRN-Unit M field and the Requested EDMG TRN-Unit P field are respectively received, the responder can send one or more EDMG BRP-RX / TX packets to the initiator. In particular, for channel combining, each EDMG BRP-RX / TX packet may be transmitted using a non-EDMG replication format. RX / TX packet to the initiator, where the TXVECTOR parameter EDMG_TRN_LEN is set to a value greater than zero, and the parameters RX_TRN_PER_TX_TRN, EDMG_TRN_M and EDMG_TRN_P are set to the values of the L-TX-RX field, the requested EDMG TRN-Unit M field and the requested EDMG TRN-Unit P field in the corresponding MIMO BF Poll frame received from the initiator , respectively. In channel aggregation, each EDMG BRP-RX / TX packets will be transmitted using the non-EDMG duplicate format.

Additionally, responders can reduce training time by transmitting each EDMG BRP-RX / X packet to train multiple TX DMG antennas simultaneously using the TRN subfield. The 'TX Antenna Mask' field of each EMDG BRP-RX / TX packet may indicate the TX DMG antenna used by the responder to transmit EDMG BRP-RX / TX packets. The 'BRP CDOWN' field of each EDMG BRP-RX / TX packet may indicate the number of remaining EDMG BRP RX / TX pits to be transmitted by the responder. The TX Antenna Mask field of each EDMG BRP-RX / TX packet shall indicate the TX DMG (TXM) field. The BRP-RX / TX packet is used to transmit the EDMG BRP-RX / TX packet to the EDMG BRP-RX / TX packet. by the responder.

Hereinafter, MIMO steps applicable to the beamforming procedure for SU / MU MIMO described above will be summarized as follows.

As shown in Figures 22-24, the initiator sends a MIMO BF setup frame to the responder for the establishment of the SU / MU MIMO BF. As described above, the initiator can request the responder to set the BF for SU-MIMO or the BF for MU-MIMO using the SU / MU field value of the MIMO BF setup frame. In particular, the initiator may request the responder from the channel measurement feedback for the link specified by the 'Link Type' through the 'MIMO FBCK-REQ' field of the MIMO BF setup frame. At this time, the MIMO BF setup frame may be transmitted without the TRN field.

3. Examples in which the present invention is applicable

Hereinafter, specific embodiments applicable to the present invention will be described in detail based on the above-described technical constitution.

First, the FST (Fast Session Transfer) applicable to the present invention will be described in detail as follows.

3-1. Fast Session Transfer (FST)

When one STA has the capability to operate in a plurality of bands, each STA can move to another band as needed and operate in the traveling band. Here, 'band' may include, for example, 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, 900 MHz and TVWSCTV White Space band of 400 to 700 MHz. In addition, if there is an additional frequency band in which the IEEE 802.11 system can be used in a license-exempt manner, the corresponding band may also be included in the 'band' of the above-mentioned meaning.

For example, when there are STAs supporting a first band (e.g., 2.4 GHz, 5 GHz) and a second band (e.g., 6 GHz, 60 GHz, etc.), one of the STAs operating in the first band It may propose movement to the second band for higher data transmission / reception rates to other STAs or other STAs.

In particular, when an access point (AP) makes such a request and the AP supports two bands, when the STA already associated with the first band moves to the second band, There is also the advantage that there is no need to perform an association operation additionally. Hereinafter, such a configuration is referred to as a co-located BSS in the present invention.

Meanwhile, the AP may support only one of the first band and the second band. In this case, the STA must perform an association operation with respect to the AP supporting the band to be moved. Hereinafter, such a configuration is referred to as a non-co-located BSS in the present invention.

In the present invention, a band switch in a co-located BSS environment and a non-co-located BSS environment is referred to as FST (Fast Session Transfer).

To summarize, in the following description, when STAs are all capable of operating in the frequency band (s) in which they wish to communicate, the FST moves the Session from one channel to another within the same or a different frequency band It can mean something.

If the variable value dot11MultibandImplemetd is TRUE, the device can support multi-band operation. For example, the variable value dot11MultibandImplemetd may be a local management information base (MIB) variable, but is not limited thereto.

Here, if one or more STAs in a multi-band capable device are members of the BSS, the devices may be referred to as members of the BSS.

The STA, which is a part of a multi-band capable device, can be used to request beacons, DMG beacons, (re) association requests, (re) association responses, information requests, information responses, probe requests, probe responses, band element in a variety of frames, such as an FST response, a FST setup response, a TDLS discovery request, a TDLS discovery response, a TDLS setup request, and a TDLS setup response frame. You can advertise.

At this time, when the STA is a part of a device supporting two or more bands or channels, the STA is configured to transmit the FST setup request frame and the FST setup response frame including only one multi- Lt; RTI ID = 0.0 > a < / RTI >

Here, if the initiator's FST session uses the same MAC address for different frequency bands / channels and the responder's FST session uses the same MAC address for different frequency bands / channels, The same FST session addressing mode may be referred to as " transparent. &Quot;

Conversely, if at least one of the initiator's FST session and the responder's FST session uses different MAC addresses for different frequency bands / channels, the FST session addressing mode is " non-transparent " can do.

25 is a diagram showing a multi-band element applicable to the present invention.

The multi-band element may be a multi-band device in which the STA transmitting the multi-band element is capable of operating in a frequency band (or operating class or channel) other than the operating band or operating class or channel through which the multi- And may indicate that the STA is capable of accomplishing a session transfer from the current channel to the other. At this time, the format of the multi-band element may be as shown in FIG.

26 is a diagram schematically showing a format of a multi-band control field applicable to the present invention.

The multi-band control field of one octet size shown in FIG. 25 may have the format structure as shown in FIG. 26 more specifically.

Here, the STA Role subfield may indicate the role of the STA transmitting the multi-band element.

The STA MAC address present subfield may indicate whether the STA MAC address subfield in the multi-band element is present. For example, if the STA MAC address presence subfield is set to one, the STA MAC address subfield may be present in the multi-band element. In contrast, if the STA MAC Address Present subfield is set to zero, the STA MAC Address subfield may not be present in the multi-band element.

The Pairwise Cipher Suite Present sub-field is used to determine whether a Pairwise Cipher Suite Count field and a Pairwise Cipher Suite List field are present in the multi- . For example, when the Pairwise Cipher Suite exists subfield is set to 1, the Pairwise Cipher Suite Count field and the Pairwise Cipher Suite List field ) May be present in the multi-band element. In contrast, when the Pairwise Cipher Suite Present subfield is set to 0, the Pairwise Cipher Suite Count field and the Pairwise Cipher Suite List field are set to " 0 & May not be present in the multi-band element.

The Band ID field provides identification of the frequency band associated with the operating class and channel number field.

The action class indicates the set of channels to which the multi-band element applies. The operation class and channel number together specify the channel frequency and spacing to which the multi-band element is applied. If the field is set to 0, it may indicate that all motion classes in the frequency band specified by the value of the band ID field are indicated.

The channel number field is set to the number of channels in which the STA that transmits the multi-band element operates or operates. If the field is set to 0, it may indicate that all channels in the frequency band specified by the value of the band ID field are indicated.

The BSSID field specifies the BSSID of the BSS operating on the channel and frequency band indicated by the channel number and band ID field.

The Beacon Interval field specifies the size of the beacon interval for the BSS operating on the channel and frequency band indicated by the Channel Number and Band ID fields. If the field is set to 0, it may mean that there is no BSS operating within the indicated channel and frequency band.

If the STA that transmitted the multi-band element is a member of the PBSS or the infrastructure BSS on both the channel indicated by the multi-band element and the channel on which the multi-band element is transmitted, the Timing Synchronization Function (TSF) The PBSS corresponding to the BSSID indicated in the Address 3 field of the MPDU (Medium Access Control Protocol Data Unit) to which the band element is transmitted or the PBSS corresponding to the STA on the indicated channel in the multi-band element with respect to the TSF of the infrastructure BSS And the time offset of the TSS of the infrastructure BSS (if the transmitting STA is a member of a PBSS or the BSS on the channel, the TSF offset field contains the time offset of the TSF of the PBSS or infrastructure BSS of which transmitting STA is the on-channel indicated in th The BSS of the TSF is the same as that of the BSS. The value of the TSF offset field is specified as a 2's complement integer in microseconds. If the STA that transmitted the multi-band element is not a member of the PBSS or the infrastructure BSS on both the channel indicated by the multi-band element and the channel on which the multi-band element is transmitted, the TSF superset value includes a value of 0 do.

Figure 27 is a simplified representation of the format of the multi-band connection capability field applicable to the present invention.

As shown in FIG. 27, a Multi-Band Connection Capability field can be defined. The multi-band connection capability field indicates the connection capability supported by the STA on the channel and band indicated by the multi-band element.

Here, the AP subfield specifies whether the corresponding STA can function as an AP on a channel and a band indicated in the multi-band element. If the STA can operate as an AP, the AP subfield is set to one. Otherwise, the AP subfield is set to zero.

The PCP subfield specifies whether the STA can function as a PCP on the indicated channel and band in the multi-band element. If the STA is able to operate as a PCP, the PCP subfield is set to one. Otherwise, the PCP subfield is set to zero.

If the STA is capable of performing DLS on the indicated channel and band in the multi-band element, the DLS (Direct Link Setup) subfield is set to one. Otherwise, the DLS subfield is set to zero.

If the STA is capable of performing Tunneled Direct Link Setup (TDLS) on the channel and band indicated in the multi-band element, the TDLS subfield is set to one. Otherwise, the TDLS subfield is set to zero.

If the STA can support the IBSS on the indicated channel and band in the multi-band element, the IBSS subfield is set to one. Otherwise, the IBSS subfield is set to zero.

The FSTSessionTimeout field in the FST setup request frame is used to indicate the timeout value for the FST session establishment protocol. The FSTSessionTimeout field includes (or indicates) a time unit unit (TU) unit after the FST setting is completed.

The STA MAC address field contains the MAC address that the STA uses while operating on the indicated channel in the multi-band element. If the STA MAC address present field is set to 0, the STA MAC address field does not exist.

When the Fair Wise Cyphersite present subfield is set to zero, the Fair Ways Cybersert count field and the Fair Ways Cypher set list field are not present in the multi-band element.

3-2. The Wi-Fi system's Hidden SSID (Service Set Identifier)

In general, a service set identifier (SSID) is a unique identifier in a header of all packets transmitted through a wireless LAN. Accordingly, when the wireless LAN client connects to the BSS, the SSID is used to distinguish each wireless LAN from the other wireless LAN.

At this time, in the wireless LAN system to which the present invention can be applied, unauthorized STAs can utilize the hidden SSID to obtain network information and to prevent access to the network.

More specifically, the network according to the present invention can implement a hidden SSID according to the following method:

- The AP is identified as hidden by advertising a wildcard SSID that is not a BSS SSID in the transmitting beacon. Here, the wildcard SSID is an SSID that can be used universally, not the SSID of the actual AP, which may be an SSID transmitted by setting the length of the SSID field to 0 or setting all the values to '1' . By configuring the wildcard SSID in this way, the AP can indicate that the corresponding SSID is a wildcard SSID.

- Only the STA that previously obtained information about the hidden network (i. E., Know the SSID in advance) may acquire network parameters (e.g., Probe) and be associated with the network.

Therefore, the AP transmits a probe response only to the STA that transmitted the probe request including the BSS SSID, and transmits a probe request including the SSID other than the BSS SSID (e.g., a wildcard SSID, etc.) The STA does not transmit the probe response.

Thus, an STA that performs active scanning without pre-provisioning can not receive a probe response in response to a probe request sent to the AP without a correct SSID element (correct SSID element).

In the wireless LAN system to which the present invention is applicable, Criteria for sending a probe response can be defined as follows.

- The STA receiving the probe request frame shall not respond to the probe request frame if any of the following apply:

a) STAs that do not match one of the following criteria:

- AP

- IBSS STA

- mesh STA

- STA (DMG STA) which is not a member of PBSS (Personal Basic Service Set) but performs active scan

- PCP

B) The STA is not a mesh STA and does not meet the following criteria at all

- If the SSID in the probe request frame is a wildcard SSID

- The SSID in the probe request frame matches the SSID of the STA.

- an SSID list element in the probe request frame exists, and the SSID list element includes the SSID of the STA's BSS (includes the SSID of the STA's BSS)

3-3. Features of wireless LAN system supporting 60 GHz

Basically, the beacon frame body of a wireless LAN system supporting the 2.4 GHz / 5 GHz band includes a mandatory SSID. In other words, the STA in the wireless LAN system supporting the 2.4 GHz / 5 GHz band must transmit the beacon frame including the SSID.

However, the SSID may optionally exist in the (DMG) beacon frame body of the wireless LAN system supporting the 60 GHz band. In other words, the STA or the AP of the wireless LAN system supporting the 60 GHz band can selectively transmit the beacon frame including the SSID.

In a wireless LAN system supporting a relatively high frequency band (eg, 60 GHz band), beamforming can be supported for efficient signal transmission and reception between STAs. In other words, the WLAN system may support a sector sweep for transmitting the beacon frame repeatedly in different sector directions (or beam directions) for the beamforming. At this time, since the SSID has a size of 32 octets (octets), the SSID does not include the SSID, thereby enabling faster signal (repeated) transmission.

In addition, in the WLAN system, it may not be obligatory to transmit a probe response corresponding to a probe request.

In addition, the SSID may be selectively present in the beacon frame body of the wireless LAN system supporting the 60 GHz band.

3-4. The Hidden SSID operation support method proposed by the present invention

In the wireless LAN system according to the present invention, the STA supporting the multi-band operation can support the FST from the current band (e.g., the first band) to another band (e.g., the second band).

However, if the AP operating in the second band operates as 'Hidden', the STA may have difficulty in obtaining the correct BSSID for the AP, and thus may not be able to access or associate with the AP, It may not be able to perform.

This may increase the power consumption of the STA as well as the interference to other STAs.

Also, when the second band is the above-mentioned 60 GHz band, the following matters related to the hidden SSID may be a problem.

The lack of SSID in the (DMG) beacon does not imply Hidden SSID behavior. In other words, the absence of the SSID in the (DMB) beacon may not necessarily mean a Hidden SSID operation.

- At initial beamforming (IBF) time, an AP can not distinguish between authorized and non-authorized STAs.

After the IBF, the AP can respond to probe requests. At this time, if the AP operates in the Hidden SSID mode and receives a probe request including a wild SSID, the AP may not transmit a probe response in response to the probe request. This may cause network parameters to not be expose to the unauthorized STA.

According to the above-described operation, the STA ignores the probe request in the existing Wi-Fi network because of the characteristics of the wireless LAN system supporting the 60 GHz band.

The probe request is a unicast frame transmitted to a known AP (known AP0), and a STA that transmits the probe request can expect a response thereto. On the other hand, in the existing Wi-Fi network, the probe request is transmitted in a broadcast frame The STA that transmits the probe request does not strongly expect a response thereto.

According to active scanning disclosed in IEEE 802.11, a wireless LAN standard, a probe exchange is required after the IBF.

The lack of probe response from the AP also causes the STA to retry transmission of the probe request, resulting in additional power consumption and a negative search time and user experience during scanning, It can have an effect.

Considering the above-described various matters, the present invention proposes the following FST operation.

28 is a diagram briefly showing an operation of supporting / performing FST of STA in a wireless LAN system applicable to the present invention.

28, the initiator means an STA that transmits an FST setup request frame, and may be an AP, a PCP / AP, and a non-AP STA. Also, the responder means an STA that receives an FST setup request frame, and may be an AP, a PCP / AP, and a non-AP STA.

It is also assumed in the following description that the responder is capable of operating in multiple bands (e.g., first and second bands) and that the initiator is also aware that the responder is capable of operating in multiple bands.

Also, in the following description, according to the embodiment, the MAC address for the first band and the MAC address for the second band of the initiator may be the same or different. Also, the MAC address for the first band of the responder and the MAC address for the second band may be the same or different.

According to the present invention, the initiator transmits an FST setup request frame to request (or propose) the responder to a band movement (e.g., first band -> second band) (S2810).

At this time, the FST setup request frame may be transmitted through the first band.

Also, as described above, the second band to which the responder is to be moved may operate in a hidden mode. In this case, the service provider (e.g., AP) of the second band broadcasts a wildcard SSID that is not its own SSID and responds only to a probe request frame including its own SSID, Can only provide services for.

In other words, if the responder performs the medium access in the second band without obtaining the correct SSID for the second band, the responder is regarded as an unauthenticated STA and is not provided with the service in the second band I can not.

Accordingly, the initiator according to the present invention transmits information indicating whether the second band operates in a hidden mode in the FST setup request frame. In addition, when the second band operates in the hidden mode, the initiator further includes a service set identifier (SSID) for the second band in the FST setup request frame.

In the present invention, information indicating whether the second band operates in a hidden mode may be transmitted through various methods.

For example, information indicating whether the second band operates in a hidden mode may be transmitted in a multi-band element included in the FST setup request frame.

As a specific method for this, the initiator can use the reserved bits (e.g., B5) of the multi-band control field shown in FIG. 26 or the reserved bits (e.g., B5) of the multi-

More specifically, when the bit value is '1', this may indicate that a new band or channel (eg, the second band) is operating in a hidden mode. Conversely, when the bit value is '0', it may indicate that a new band or channel (eg, a second band) operates in a normal mode. In this case, the example of the bit value is only an example applicable to the present invention, and various values that can be distinguished from each other can be applied to the bit values.

As such, information indicating whether the second band operates in the hidden mode can be transmitted in a multi-band control field included in the multi-band element. Alternatively, in another example, information indicating whether the second band operates in a hidden mode may be transmitted in a multi-band connection capability field included in the multi-band element.

However, in the present invention, the information indicating whether the second band operates in a hidden mode may be transmitted through an element or field other than the multi-band element.

Additionally, if a new band or channel (e.g., a second band) is indicated as a hidden mode through various examples described above, an STA (e.g., AP or PCP / AP) that transmits an FST setup request frame may request an FST setup request And the SSID information of the new band or channel in the frame. At this time, the SSID information may be represented by the SSID element format as shown in FIG.

29 is a diagram showing an SSID element format applicable to the present invention.

For example, if a new band or channel (e.g., a second band) is indicated as a hidden mode through various examples described above, the initiator may transmit the FST setup request frame action field including the SSID element format.

The responder receiving the FST setting request frame can transmit the FST setting response frame to the initiator as a response thereto (S2820). The operation may be selectively applied.

At this time, the FST setup response frame may be transmitted through the first band in the same manner as the FST setup request frame.

Additionally, the initiator may send an FST ACK request frame to the responder to confirm the FST performance (S2830). As a response to the FST ACK request frame, the responder may transmit the FST ACK response frame to the initiator (S2840).

Here, the FST ACK request frame and the FST ACK response frame may be transmitted and received after the initiator and the responder are determined to perform the FST. Therefore, the FST ACK request frame and the FST ACK response frame may be transmitted through the second band, unlike the FST setup request frame and the FST setup response frame.

Next, the responder whose transmission band is switched from the first band to the second band through the FST performs media connection for the second band (S2850).

Here, the medium connection may include some or all of the link establishment process shown in FIG.

Therefore, for example, when the second band operates in the hidden mode, the responder transmits the probe request frame including the SSID of the second band received as the medium access procedure for the second band to a separate AP or the like Lt; / RTI > At this time, the separate AP may be the same STA as the initiator or a different STA. More specifically, according to the present invention, the target station in which the responder performs media access for the second band may be a STA different from the initiator described above.

In such a configuration, the first band may correspond to one of the 2.4 GHz band, the 5 GHz band, and the 6 GHz band, but the operation proposed in the present invention is not limited to the above-mentioned band.

In addition, the second band may correspond to one of 2.4 GHz band, 5 GHz band, 6 GHz band, and 60 GHz band, which is different from the first band. It is not limited to one band.

In a specific example, if the second band is a 60 GHz band, the responder may switch between a separate (beamforming) initiator and a responder transmission sector sweep (R-TXSS) after switching to the second band according to the FST performed Can be performed. Thereafter, when the second band operates in the hidden mode, the responder transmits a probe request frame using the SSID received through the FST setup request frame, receives the probe response frame in response to the probe request frame, can do.

4. Device Configuration

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

The wireless device 100 of FIG. 30 may correspond to the initiator described in the foregoing description, and the wireless device 150 may correspond to the responder described in the foregoing description.

At this time, the initiator may correspond to a terminal or AP (or PCP / AP) supporting the wireless LAN system, and the responder may correspond to a terminal or an AP (or PCP / AP) supporting the wireless LAN system.

The transmitting apparatus 100 may include a processor 110, a memory 120 and a transmitting and receiving unit 130. The receiving apparatus 150 may include a processor 160, a memory 170 and a transmitting and receiving unit 180 can do. The transceivers 130 and 180 transmit / receive wireless signals and may be implemented in a physical layer such as IEEE 802.11 / 3GPP. The processors 110 and 160 are implemented in the physical layer and / or the MAC layer and are connected to the transceiving units 130 and 180.

The processors 110 and 160 and / or the transceivers 130 and 180 may include application specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processors. Memory 120, 170 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage units. 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 initiator thus configured can transmit an FST setup request frame for requesting the responder to set the FST from the first band to the second band using the processor and the transceiver. At this time, the FST setup request frame may include information indicating whether the second band operates in a hidden mode. In addition, when the second band operates in the hidden mode, the FST setup request frame may further include a service set identifier (SSID) for the second band.

Correspondingly, the responder receives the FST setup request frame requesting the FST setup from the first band to the second band from the initiator using the processor and the transceiver, and receives the FST setup request frame After the FST, the association procedure in the second band can be performed. In this case, as described above, the FST setup request frame includes information indicating whether the second band operates in a hidden mode, and in particular, when the second band operates in a hidden mode, The FST setup request frame may further include a service set identifier (SSID) for the second band. In addition, when the second band operates in the hidden mode, the association procedure in the second band may be performed based on the SSID of the second band included in the FST setup request frame.

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.

Although the present invention has been described on the assumption that the present invention is applied to an IEEE 802.11 based wireless LAN system, the present invention is not limited thereto. The present invention can be applied to various wireless systems capable of data transmission based on channel bonding in the same manner.

Claims (18)

1. A method for performing Fast Session Transfer (FST) in a first station (STA) operable in a first band and a second band in a wireless local area network (WLAN) system,

   Receiving an FST setup request frame from the second STA requesting FST setup from the first band to the second band; And

   Performing an association procedure in the second band after FST including reception of the FST setup request frame,

   Wherein the FST setup request frame includes information indicating whether the second band operates in a hidden mode,

   Wherein when the second band operates in a hidden mode, the FST setup request frame further includes a service set identifier (SSID) for the second band,

   And when the second band operates in the hidden mode, the association procedure in the second band is performed based on the SSID for the second band included in the FST setup request frame.
2. The method according to claim 1,

   The FST method includes:

   Further comprising: in response to the FST configuration response frame, the first STA transmitting an FST configuration response frame to the second STA.
3. 3. The method of claim 2,

   Wherein the FST setup request frame and the FST setup response frame are transmitted on the first band.
4. 3. The method of claim 2,

   The FST method includes:

   Receiving an FST ACK request frame from the second STA requesting confirmation of FST performance; And

   Further comprising: in response to the FST ACK request frame, the first STA transmitting an FST ACK response frame to the second STA.
5. 5. The method of claim 4,

   Wherein the FST ACK request frame and the FST ACK response frame are transmitted through the second band.
6. The method according to claim 1,

   Wherein information indicating whether the second band operates in a hidden mode is transmitted in a multi-band element included in the FST configuration request frame.
7. The method according to claim 6,

   Information indicating whether the second band operates in a hidden mode is transmitted in a multi-band control field or a multi-band connection capability field included in the multi-band element , FST method.
8. The method according to claim 1,

   When the second band operates in the hidden mode, the SSID for the second band is included in the FST Setup Request frame Action field in the FST setup request frame.
9. The method according to claim 1,

   And the association procedure in the second band, which is performed based on the SSID for the second band when the second band operates in the hidden mode,

   And transmitting the probe request frame including the SSID for the second band included in the FST setup request frame by the first STA.
10. The method according to claim 1,

    Wherein the first band corresponds to one of the 2.4 GHz band, the 5 GHz band, and the 6 GHz band.
11. 11. The method of claim 10,

    Wherein the second band corresponds to one of the 2.4 GHz band, the 5 GHz band, the 6 GHz band, and the 60 GHz band, which is different from the first band.
12. The method according to claim 1,

    Wherein the target STA, in which the first STA performs the association procedure in the second band,

    Wherein the STA is different from the second STA.
13. A method of supporting Fast Session Transfer (FST) of a second STA operable in a first band and a second band in a first station (STA) in a wireless LAN (WLAN) system,

    And transmitting an FST setup request frame requesting the second STA to set up the FST from the first band to the second band,

    Wherein the FST setup request frame includes information indicating whether the second band operates in a hidden mode,

    Wherein the FST setup request frame further comprises a service set identifier (SSID) for the second band when the second band operates in a hidden mode.
14. 14. The method of claim 13,

    Wherein information indicating whether the second band operates in a hidden mode is transmitted in a multi-band element included in the FST setup request frame.
15. 15. The method of claim 14,

    Information indicating whether the second band operates in a hidden mode is transmitted in a multi-band control field or a multi-band connection capability field included in the multi-band element , FST support method.
16. 14. The method of claim 13,

    When the second band operates in the hidden mode, the SSID for the second band is included in the FST Setup Request frame Action field in the FST setup request frame.
17. A station apparatus capable of operating in a first band and a second band in a wireless local area network (WLAN) system and performing FST (Fast Session Transfer)

    A transceiver configured to transmit and receive signals with one or more other station devices, the station having one or more RF (Radio Frequency) chains; And

    And a processor coupled to the transceiver for processing signals transmitted to and received from the one or more other station devices,

    The processor comprising:

    Receiving an FST setup request frame from the second STA requesting FST setup from the first band to the second band; And

    Performing an association procedure in the second band after an FST including reception of the FST setup request frame,

    Wherein the FST setup request frame includes information indicating whether the second band operates in a hidden mode,

    Wherein when the second band operates in a hidden mode, the FST setup request frame further includes a service set identifier (SSID) for the second band,

    And when the second band operates in the hidden mode, the association procedure in the second band is performed based on the SSID for the second band included in the FST setup request frame.
18. A station device supporting Fast Session Transfer (FST) for a first station device operable in a first band and a second band in a wireless local area network (WLAN) system,

    A transceiver configured to transmit and receive signals with one or more other station devices, the station having one or more RF (Radio Frequency) chains; And

    And a processor coupled to the transceiver for processing signals transmitted to and received from the one or more other station devices,

    The processor is configured to send an FST setup request frame to the first station device requesting FST setup from the first band to the second band,

    Wherein the FST setup request frame includes information indicating whether the second band operates in a hidden mode,

    Wherein the FST setup request frame further includes a service set identifier (SSID) for the second band when the second band operates in a hidden mode.

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