WO2013154389A1 - 액티브 스캐닝 방법 및 장치 - Google Patents
액티브 스캐닝 방법 및 장치 Download PDFInfo
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- WO2013154389A1 WO2013154389A1 PCT/KR2013/003097 KR2013003097W WO2013154389A1 WO 2013154389 A1 WO2013154389 A1 WO 2013154389A1 KR 2013003097 W KR2013003097 W KR 2013003097W WO 2013154389 A1 WO2013154389 A1 WO 2013154389A1
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- sta
- request frame
- probe request
- frame
- probe
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W48/00—Access restriction; Network selection; Access point selection
- H04W48/16—Discovering, processing access restriction or access information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W8/00—Network data management
- H04W8/005—Discovery of network devices, e.g. terminals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/10—Small scale networks; Flat hierarchical networks
- H04W84/12—WLAN [Wireless Local Area Networks]
Definitions
- the present invention relates to a method and apparatus for scanning a station (STA), and more particularly, to a method and apparatus for an STA to perform active scanning.
- STA station
- the present invention relates to a method and apparatus for scanning a station (STA), and more particularly, to a method and apparatus for an STA to perform active scanning.
- IEEE 802.11ac is a wireless LAN technology using a 60GHz band.
- IEEE 802.11af which utilizes a TV white space (TVWS) band.
- IEEE 802.11ah utilizing the 900MHz band. They aim primarily at the expansion of extended grid Wi-Fi services, as well as smart grid and wide area sensor networks.
- the existing WLAN medium access control (MAC) technology has a problem that the initial link setup time is very long in some cases.
- the IEEE 802.11ai standardization activity has been actively performed recently.
- IEEE 802.11ai is a MAC technology that addresses the rapid authentication process to drastically reduce the initial set-up and association time of WLAN. Standardization activities began in January 2011 as a formal task group. It became. In order to enable the fast access procedure, IEEE 802.11ai is based on AP discovery, network discovery, time synchronization function synchronization, Authentication & Association, and higher layer. Discussion of process simplification is underway in areas such as merging procedures with the Among them, procedure merging using piggyback of dynamic host configuration protocol (DHCP), optimization of full EAP (extensible authentication protocol) using concurrent IP, and efficient selective access (AP) point) Ideas such as scanning are actively discussed.
- DHCP dynamic host configuration protocol
- EAP efficient selective access
- An object of the present invention is to provide an active scanning method of a station (STA).
- Another object of the present invention is to provide an apparatus for performing an active scanning method of a station (STA).
- an active scanning method in a WLAN in which a second STA receives a first probe request frame broadcast from a first STA.
- 2 STA may include broadcasting a second probe request frame, wherein the second probe request frame includes a probe request frame detection field, and wherein the probe request frame detection field is determined by the second STA. It may indicate that a probe request frame has been received.
- the second probe request frame may further include information about an identifier of the first STA.
- the second STA may further include receiving a beacon frame or a probe response frame that is a response to the second probe request frame from an access point (AP).
- AP access point
- the AP may broadcast the probe response frame when the information to be transmitted to the first STA and the second STA is the same in response to the first probe request frame and the second probe request frame.
- the AP has the same information to be transmitted to the first STA and the second STA in response to the first probe request frame and the second probe request frame, and the probe response of the first STA and the second STA.
- the transmission time of the beacon frame is returned at the time of monitoring a frame, the beacon frame is broadcasted, and the AP broadcasts the first STA and the second STA in response to the first probe request frame and the second probe request frame.
- the probe response frame is broadcast. can do.
- the first STA may set a probe timer to a maximum channel time, wherein the probe timer determines whether to move the channel scanned by the first STA. It can be determined based on the set time.
- the WLAN device includes a processor, the processor is a first probe request broadcast from a first STA (station)
- the second STA may be implemented to receive a frame and the second STA broadcasts a second probe request frame, wherein the second probe request frame includes a probe request frame detection field, and the probe request frame detection field is
- the second STA may indicate that the first probe request frame has been received.
- the second probe request frame may further include information about an identifier of the first STA.
- the processor may be implemented such that the second STA receives a beacon frame or a probe response frame in response to the second probe request frame from an access point (AP).
- AP access point
- the AP may broadcast the probe response frame when the information to be transmitted to the first STA and the second STA is the same in response to the first probe request frame and the second probe request frame.
- the AP has the same information to be transmitted to the first STA and the second STA in response to the first probe request frame and the second probe request frame, and the probe response of the first STA and the second STA.
- the transmission time of the beacon frame is returned at the time of monitoring a frame, the beacon frame is broadcasted, and the AP broadcasts the first STA and the second STA in response to the first probe request frame and the second probe request frame.
- the probe response frame is broadcast. can do.
- the first STA may set a probe timer to a maximum channel time, wherein the probe timer determines whether to move the channel scanned by the first STA. It can be determined based on the set time.
- the scanning procedure may be simplified by broadcasting a probe response frame to a plurality of stations.
- WLAN wireless local area network
- FIG. 2 is a conceptual diagram illustrating a scanning method in a WLAN.
- FIG. 3 is a conceptual diagram illustrating an authentication and combining process after scanning of an AP and an STA.
- 4 is a conceptual diagram for an active scanning procedure.
- FIG. 5 is a conceptual diagram illustrating a method for transmitting a probe request frame.
- FIG. 6 is a conceptual diagram illustrating an active scanning method according to an embodiment of the present invention.
- FIG. 7 is a conceptual diagram illustrating an active scanning method according to an embodiment of the present invention.
- FIG. 8 is a conceptual diagram illustrating a probe request frame according to an embodiment of the present invention.
- FIG. 9 is a flowchart illustrating a method of performing active scanning according to an embodiment of the present invention.
- FIG. 10 is a conceptual diagram illustrating a scanning method according to an embodiment of the present invention.
- FIG. 11 is a conceptual diagram illustrating a method of determining whether an AP transmits a probe response frame according to an embodiment of the present invention.
- FIG. 12 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.
- WLAN wireless local area network
- FIG. 1A shows the structure of an infrastructure network of the Institute of Electrical and Electronic Engineers (IEEE) 802.11.
- IEEE Institute of Electrical and Electronic Engineers
- the WLAN system may include one or more basic service sets (BSSs) 100 and 105.
- the BSSs 100 and 105 are a set of APs and STAs such as an access point 125 and a STA1 (station 100-1) capable of successfully synchronizing and communicating with each other, and do not indicate a specific area.
- the BSS 105 may include one or more joinable STAs 105-1 and 105-2 to one AP 130.
- the infrastructure BSS may include at least one STA, APs 125 and 130 that provide a distribution service, and a distribution system DS that connects a plurality of APs.
- the distributed system 110 may connect several BSSs 100 and 105 to implement an extended service set (ESS) 140 which is an extended service set.
- ESS 140 may be used as a term indicating one network in which one or several APs 125 and 230 are connected through the distributed system 110.
- APs included in one ESS 140 may have the same service set identification (SSID).
- the portal 120 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (for example, 802.X).
- a network between the APs 125 and 130 and a network between the APs 125 and 130 and the STAs 100-1, 105-1, and 105-2 may be implemented. have. However, it may be possible to perform communication by setting up a network even between STAs without the APs 125 and 130.
- a network that performs communication by establishing a network even between STAs without APs 125 and 130 is defined as an ad-hoc network or an independent basic service set (BSS).
- 1B is a conceptual diagram illustrating an independent BSS.
- an independent BSS is a BSS operating in an ad-hoc mode. Since IBSS does not contain an AP, there is no centralized management entity. That is, in the IBSS, the STAs 150-1, 150-2, 150-3, 155-1, and 155-2 are managed in a distributed manner. In the IBSS, all STAs 150-1, 150-2, 150-3, 155-1, and 155-2 may be mobile STAs, and access to a distributed system is not allowed, thus allowing a self-contained network. network).
- a STA is any functional medium that includes a medium access control (MAC) and physical layer interface to a wireless medium that conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. May be used to mean both an AP and a non-AP STA (Non-AP Station).
- MAC medium access control
- IEEE Institute of Electrical and Electronics Engineers
- the STA may include a mobile terminal, a wireless device, a wireless transmit / receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit ( It may also be called various names such as a mobile subscriber unit or simply a user.
- WTRU wireless transmit / receive unit
- UE user equipment
- MS mobile station
- UE mobile subscriber unit
- It may also be called various names such as a mobile subscriber unit or simply a user.
- FIG. 2 is a conceptual diagram illustrating a scanning method in a WLAN.
- a scanning method may be classified into passive scanning 200 and active scanning 250.
- the passive scanning 200 may be performed by the beacon frame 230 that the AP 200 periodically broadcasts.
- the AP 200 of the WLAN broadcasts the beacon frame 230 to the non-AP STA 240 every 100 msec.
- the beacon frame 230 may include information about the current network.
- the non-AP STA 240 receives the beacon frame 230 that is periodically broadcast to receive the network information to perform scanning for the AP 210 and the channel to perform the authentication / association (authentication / association) process Can be.
- the passive scanning method 200 only needs to receive the beacon frame 230 transmitted from the AP 210 without requiring the non-AP STA 240 to transmit the frame.
- passive scanning 200 has the advantage that the overall overhead incurred by data transmission / reception in the network is small.
- scanning can be performed manually in proportion to the period of the beacon frame 230, the time taken to perform scanning increases.
- the active scanning 250 refers to a method in which a non-AP STA 290 transmits a probe request frame 270 to the AP 260 to proactively perform scanning.
- the AP 260 After receiving the probe request frame 270 from the non-AP STA 290, the AP 260 waits for a random time to prevent frame collision, and then includes network information in the probe response frame 280. may transmit to the non-AP STA 290. The non-AP STA 290 may obtain network information based on the received probe response frame 280 and stop the scanning process.
- the probe request frame 270 is disclosed in IEEE 802.11 8.3.3.9 and the probe response frame 280 is disclosed in IEEE 802.11 8.3.3.10.
- the AP and the STA may perform an authentication and association process.
- FIG. 3 is a conceptual diagram illustrating an authentication and combining process after scanning of an AP and an STA.
- the authentication and association process may be performed through, for example, two-way handshaking.
- 3 (A) is a conceptual diagram showing an authentication and combining process after passive scanning
- FIG. 3 (B) is a conceptual diagram showing an authentication and combining process after active scanning.
- the authentication and association process is based on an authentication request frame 310 / authentication response frame 320 and an association request frame 330 regardless of whether an active scanning method or passive scanning is used. The same may be performed by exchanging an association response frame 340 between the APs 300 and 350 and the non-AP STAs 305 and 355.
- the authentication process may be performed by transmitting the authentication request frame 310 to the APs 300 and 350 in the non-AP STAs 305 and 355.
- the authentication response frame 320 may be transmitted from the APs 300 and 350 to the non-AP STAs 305 and 355.
- Authentication frame format is disclosed in IEEE 802.11 8.3.3.11.
- An association process may be performed by transmitting an association request frame 330 to the APs 300 and 305 in the non-AP STAs 305 and 355.
- the association response frame 340 may be transmitted from the AP 305 and 355 to the non-AP STAs 300 and 350.
- the transmitted association request frame 330 includes information on the capabilities of the non-AP STAs 305 and 355. Based on the performance information of the non-AP STAs 305 and 355, the APs 300 and 350 may determine whether support is possible for the non-AP STAs 305 and 355.
- the AP 300 or 350 may include the non-AP STA 305 in the association response frame 340 by including whether the acceptance request frame 330 is accepted and the reason thereof, and capability information that can be supported. , 355).
- Association frame format is disclosed in IEEE 802.11 8.3.3.5/8.3.3.6.
- the association may be performed again or the association may be performed to another AP based on the reason why the association is not performed.
- 4 is a conceptual diagram for an active scanning procedure.
- the active scanning procedure may be performed in the following steps.
- the STA 400 determines whether it is ready to perform a scanning procedure.
- the STA 400 may perform active scanning by waiting until the probe delay time expires or when specific signaling information (eg, PHY-RXSTART.indication primitive) is received. have.
- specific signaling information eg, PHY-RXSTART.indication primitive
- the probe delay time is a delay that occurs before the STA 400 transmits the probe request frame 410 when performing the active scanning.
- PHY-RXSTART.indication primitive is a signal transmitted from a physical (PHY) layer to a local medium access control (MAC) layer.
- the PHY-RXSTART.indication primitive may signal to the MAC layer that it has received a PLC protocol data unit (PPDU) including a valid PLCP header in a physical layer convergence protocol (PLCP).
- PPDU PLC protocol data unit
- PLCP physical layer convergence protocol
- DCF distributed coordination function
- CSMA / CA carrier sense multiple access / collision avoidance
- the probe request frame 410 includes information for specifying the APs 460 and 470 included in the MLME-SCAN.request primitive (eg, service set identification (SSID) and basic service set identification (BSSID) information). ) Can be sent.
- SSID service set identification
- BSSID basic service set identification
- the BSSID is an indicator for specifying the AP and may have a value corresponding to the MAC address of the AP.
- Service set identification (SSID) is a network name for specifying an AP that can be read by a person who operates an STA. The BSSID and / or SSID may be used to specify the AP.
- the STA 400 may specify the AP based on information for specifying the APs 460 and 470 included by the MLME-SCAN.request primitive.
- the specified APs 460 and 470 may transmit probe response frames 440 and 450 to the STA 400.
- the STA 400 may unicast, multicast, or broadcast the probe request frame 410 by transmitting the SSID and BSSID information in the probe request frame 410. A method of unicasting, multicasting or broadcasting the probe request frame 410 using the SSID and the BSSID information will be further described with reference to FIG. 5.
- the STA 400 may include the SSID list in the probe request frame 410 and transmit the SSID list.
- the AP 460 or 470 receives the probe request frame 410 and determines the SSID included in the SSID list included in the received probe request frame 410 to determine the probe response frames 440 and 450 to the STA 200. You can decide whether to send.
- the probe timer may be used to check the minimum channel time MinChanneltime 420 and the maximum channel time MaxChanneltime 430.
- the minimum channel time 420 and the maximum channel time 430 may be used to control the active scanning operation of the STA 400.
- the minimum channel time 420 may be used to perform an operation for changing a channel on which the STA 400 performs active scanning. For example, when the STA 400 does not receive the probe response frames 440 and 450 until the minimum channel time 420, the STA 400 may shift the scanning channel to perform scanning on another channel. When the STA 400 receives the probe response frame 440 until the minimum channel time 420, the STA 400 may process the received probe response frames 440 and 450 by waiting for the maximum channel time 430.
- the STA 400 detects the PHY-CCA.indication primitive until the probe timer reaches the minimum channel time 420 and then another frame (eg, probe response frames 440 and 450) until the minimum channel time 420. Whether it is received by the STA 400 may be determined.
- PHY-CCA.indication primitive may transmit information about the state of the medium from the physical layer to the MAC layer. PHY-CCA.indication primitive can inform the status of the current channel by using channel status parameters such as busy if channel is not available and idle if channel is available. If the PHY-CCA.indication is detected as busy, the STA 400 determines that the probe response frames 440 and 450 received by the STA 400 exist and the PHY-CCA.indication is idle. If it is detected as, it may be determined that the probe response frames 440 and 450 received by the STA 400 do not exist.
- the STA 400 may set the net allocation vector (NAV) to 0 and scan the next channel.
- PHY-CCA.indication is detected as busy, the STA 400 may perform processing on received probe response frames 440 and 450 after the probe timer reaches the maximum channel time 430. have. After processing the received probe response frames 440 and 450, the net allocation vector (NAV) is set to 0 and the STA 400 may scan the next channel.
- determining whether the probe response frames 440 and 450 received by the STA 400 exist may include determining the channel state using the PHY-CCA.indication primitive. have.
- the MLME may signal MLME-SCAN.confirm primitive.
- the MLME-SCAN.confirm primitive may include a BSSDescriptionSet including all information obtained in the scanning process.
- the STA 400 uses the active scanning method, it is necessary to perform monitoring to determine whether the parameter of the PHY-CCA.indication is busy until the probe timer reaches the minimum channel time.
- FIG. 5 is a conceptual diagram illustrating a method for transmitting a probe request frame.
- FIG. 5 illustrates a method in which an STA broadcasts, multicasts, and unicasts a probe request frame.
- 5A illustrates a method in which the STA 500 broadcasts a probe request frame 510.
- the STA 500 may broadcast the probe request frame 510 by including a wildcard SSID and a wildcard BSSID in the probe request frame 510.
- the wild card SSID and wild card BSSID may be used as an identifier for indicating all of the APs 505-1, 505-2, 505-3, 505-4, and 505-5 included in the transmission range of the STA 500. .
- the AP 505-1, 505- receiving the probe request frame 510 transmitted by the STA 500. 2, 505-3, 505-4, and 505-5 may transmit a probe response frame to the STA 500 in response to the received probe request frame.
- the AP 505-1, 505-2, 505-3, 505-4, and 505-5 receiving the broadcast probe request frame 510 respond to the received probe request frame 510 in response to the probe response frame. If the STA 500 transmits the STA 500 within a predetermined time, the STA 500 may receive and process too many probe response frames at once.
- 5B illustrates a method in which the STA 520 unicasts the probe request frame 530.
- the STA 520 may include a probe request frame 530 including specific SSID / BSSID information of the AP. Can be transmitted. Among the APs receiving the probe request frame 530, only the AP 525 corresponding to the specific SSID / BSSID of the AP 520 may transmit a probe response frame to the STA 520.
- 5C illustrates a method in which the STA 540 multicasts the probe request frame 560.
- the STA 540 may include the SSID list and the wild card BSSID in the probe request frame 560.
- APs 550-1 and 550-2 corresponding to the SSID included in the SSID list included in the probe request frame among the APs receiving the probe request frame 560 may transmit a probe response frame to the STA 540.
- an embodiment of the present invention discloses a method in which an AP broadcasts a probe response frame to a plurality of STAs.
- the AP disclosed in the embodiment of the present invention is a fast initial link setup capable AP (FILS) capable in other terms, and the STA is capable of establishing a fast initial link in other terms STA (fast initial link) setup) capable STA).
- FILS fast initial link setup capable AP
- STA fast initial link setup
- the AP may receive a probe request frame from a plurality of STAs and may broadcast a probe response frame to the plurality of STAs in response thereto.
- the STA performing active scanning may set the probe timer to '0' after transmitting the probe request frame. If the STA receives another frame (eg, probe response frame) before the probe timer reaches the minimum channel time (MinChannelTime), the STA can perform active scanning until the probe timer reaches the maximum channel time (MaxChannelTime). have.
- MinChannelTime minimum channel time
- MaxChannelTime maximum channel time
- the STA may perform active scanning by changing the scanning channel to another channel.
- the AP may transmit a probe response frame to the STA.
- the AP must broadcast a probe response frame before the STA that has sent the probe request frame changes the scanning channel to another channel.
- FIG. 6 is a conceptual diagram illustrating an active scanning method according to an embodiment of the present invention.
- a first STA 660 first broadcasts a probe request frame in a BSS in which one AP 650, a first STA 660, a second STA 670, and a third STA 680 exist. Next, it is assumed that the second STA 670 broadcasts a probe request frame.
- the first STA 660 broadcasts a probe request frame (step S600).
- the first STA 660 may broadcast a probe request frame.
- the probe request frame broadcast by the first STA 660 may be received by at least one device of the second STA 670, the third STA 680, and the AP 650.
- the AP 650 does not receive the probe request frame broadcast by the first STA 660
- the second STA 670 or the third STA 680 broadcasts the probe request frame broadcast by the first STA 660. May be received.
- the AP 650 broadcasts a probe response frame to the plurality of STAs 660, 670, and 680. Even when the AP 650 does not directly receive a probe request frame from the first STA 660, the AP 650 may determine that the first STA 660 is based on the probe request frame received from the second STA 670. It can be seen that the probe request frame has been broadcast. In this case, the AP 650 broadcasts a probe response frame so that the first STA 660 and the second STA 670 may receive the probe response frame transmitted by the AP 650 to perform scanning. This is described in detail below.
- the second STA 670 broadcasts a probe request frame (step S620).
- the second STA 670 Before the second STA 670 broadcasts the probe request frame, the second STA 670 is medium for a certain time interval (eg, probe delay and distributed coordination function interframe space, etc.). ) Needs to be searched to see if it is idle. If the medium is 'busy', the second STA 670 may perform a back-off operation before transmitting the probe request frame.
- a certain time interval eg, probe delay and distributed coordination function interframe space, etc.
- the second STA 670 may receive the probe request frame broadcast by the first STA 660 through step S600 before broadcasting the probe request frame.
- the probe request frame broadcast by the second STA 670 may include information indicating that the second STA 670 has received the probe request frame broadcast by the first STA 660.
- Information indicating that the first STA 660 has received the broadcast request request frame may be defined in a field called a probe request frame detection field and included in the probe request frame.
- the probe request frame detection field may include, for example, identifier information of the STA that transmitted the probe request frame so that the AP generates and broadcasts a probe response frame based on the identifier information of the STA.
- the probe request frame detection field may be used as flag information to indicate only information on whether a probe request frame has been received from another STA.
- the probe request frame detection field may be transmitted as a single information format in which the same information is defined in various information formats.
- the first STA 660 may receive a probe request frame broadcast by the second STA 670 and reset the probe timer to the maximum channel time.
- the PHY-CCA.indication primitive is measured as 'busy' at the first STA 660.
- the first STA 660 may reset the probe timer to the maximum channel time.
- the AP 650 broadcasts a probe response frame (step S640).
- the AP 650 When the AP 650 receives the probe request frame from both the first STA 660 and the second STA 670 or fails to receive the probe request frame from the first STA 660, the AP 650 receives the probe request frame from the second STA 670. Only probe request frames can be received.
- the AP 650 may respond to the probe response. It may be determined whether to broadcast the frame.
- the probe request frame transmitted by the second STA 670 may include a probe request frame detection field.
- the AP 650 may determine whether a probe request frame is broadcast from another STA (eg, the first STA 660) other than the second STA 670 based on the probe request frame detection field.
- the AP 650 includes a first probe request frame detection field in the probe request frame transmitted by the second STA 670. It may be determined whether to transmit a probe response frame to the STA 660. For example, it may be determined whether a probe response frame has already been transmitted to the first STA 660 based on the identifier information of the first STA 660 included in the frame detection field, and to the first STA 660. If the probe response frame is not transmitted, the probe response frame may be broadcast to the first STA 660 and the second STA 670.
- the AP 650 may include the first STA until the probe timer of the first STA 660 reaches the maximum channel time based on the probe request frame detection field in the probe request frame transmitted by the second STA 670. It can be seen that 660 will not change the channel. That is, the AP 650 may know that the first STA 660 resets the probe timer to the maximum channel time due to the probe request frame broadcast by the second STA 670. Accordingly, when the AP 650 transmits a probe response frame to the first STA 660 and the second STA 670, the maximum channel time of the first STA 660 and the probe timer of the second STA 670 expire. The probe response frame may be broadcast in consideration of the time until now. The probe timer may determine whether to move the channel scanned by the STA based on the set time.
- the probe request frame may not be separately transmitted.
- the third STA 680 may receive a probe request frame broadcast by the first STA 660 and the second STA 670.
- the third STA 680 may know that the AP 650 will broadcast a probe response frame based on the probe request frame broadcast by the first STA 660 and the second STA 670.
- the third STA 680 may perform scanning based on the received probe response frame by receiving the probe response frame broadcast by the AP 650 without separately broadcasting the probe request frame to the AP 650. It may be.
- the second STA 670 may receive the probe request frame broadcast by the first STA 660 before broadcasting the probe request frame.
- the second STA 670 may broadcast a probe request frame including information indicating that the first STA 660 has transmitted the probe request frame.
- the AP 650 may broadcast a probe response frame before STAs 660 and 670 that broadcast the probe request frame change the scanning channel to another channel.
- the STAs 660 and 670 may include information on the minimum channel time and the maximum channel time in the probe request frame and transmit the same.
- FIG. 7 is a conceptual diagram illustrating an active scanning method according to an embodiment of the present invention.
- the first STA detects whether the medium is idle and transmits a probe request frame before transmitting the probe request frame (step S700).
- Checking of the medium may be performed during certain time intervals (eg, probe delay, DIFS, etc.). If the first STA has not received a probe request frame broadcast by any other STA during a particular time interval, the first STA includes information indicating that no signal has been detected (eg, no probe request frame indication).
- the probe request frame may be transmitted to the AP. For example, the first STA may transmit information including information indicating that no signal is detected in the probe request frame detection field included in the probe request frame.
- the first STA sets the probe timer to the minimum channel time (step S710).
- the first STA may set the probe timer to the minimum channel time after broadcasting the probe request frame.
- the second STA may transmit a probe request frame including information for indicating that the probe request frame has been received from another STA to the AP (step S720). ).
- the second STA may detect whether the medium is idle before transmitting the probe request frame.
- the second STA may receive a probe request frame from another STA (eg, the first STA) during the period of detecting the medium.
- the second STA may transmit a probe request frame including information indicating that the probe request frame has been received from another STA to the AP.
- the second STA may transmit information including information indicating that the probe request frame has been received from another STA in the probe request frame detection field included in the probe request frame.
- the first STA may increase and set the probe timer from the minimum channel time to the maximum channel time (step S730).
- the PHY-CCA.indication primitive is detected as 'busy', and in this case, the first STA may reset the minimum channel time to the maximum channel time. That is, the first STA may receive a probe response frame broadcast by the AP for a time set as the maximum channel time.
- the AP broadcasts a probe response frame (step S740).
- the AP may broadcast a probe response frame before the time set in the first STA and the second STA elapses and moves to another channel.
- the first STA and the second STA may receive a probe response frame from the AP.
- the probe timer of the first STA may be set to the maximum channel time and the probe timer of the second STA to the minimum channel time through the above-described procedure.
- the UE may broadcast a probe response frame before each of the set time periods of the probe timers of the first STA and the second STA expires.
- Step S740 may be applied to the case where individual request information is not included in the probe request frame transmitted by the plurality of STAs as an embodiment.
- the AP may broadcast a probe response frame without having to unicast an individual probe response frame to each STA.
- the AP transmission method broadcasts a probe response frame when information to be transmitted to the plurality of STAs is the same even when individual request information is included in the probe request frame transmitted by the plurality of STAs according to the AP's decision. You can also cast In addition, even when the information to be transmitted from the AP to the plurality of STAs is not the same, there may be a case in which a probe response frame is broadcast according to the AP's decision.
- the AP may broadcast the probe response frame to the plurality of STAs without having to transmit the probe response frame to each STA through a plurality of procedures.
- the AP may transmit a probe response frame to an STA that does not directly receive the probe request frame.
- FIG. 8 is a conceptual diagram illustrating a probe request frame according to an embodiment of the present invention.
- the probe request frame may include information on whether a probe request frame is transmitted from another STA as a field 800 of the probe request frame.
- the probe request frame may include a probe request frame detection field 800.
- the STA may transmit information on whether there is a probe request frame transmitted from another STA using the probe request frame detection field 800 to the AP.
- the probe request frame detection field 800 may include various information.
- the probe request frame detection field 800 may include identifier information of the STA that transmitted the probe request frame.
- the AP may broadcast the information specified as the STA in the probe response frame based on the identifier information of the STA included in the probe request frame detection field 800.
- the probe request frame detection field 800 may be used to indicate only information on whether a probe request frame has been received from another STA as flag information.
- the AP may determine that the probe request frame has been transmitted from another STA and broadcast the probe response frame so that the plurality of STAs may receive the probe response frame.
- FIG. 9 is a flowchart illustrating a method of performing active scanning according to an embodiment of the present invention.
- step S900 it is determined whether a probe request frame transmitted by another STA is received before transmitting the probe request frame.
- the STA may determine whether the medium is an idle for a specific time interval before transmitting the probe request frame.
- the STA may receive a probe request frame broadcasted by another STA.
- the period for receiving the probe request frame may be a time interval other than the time for determining whether the medium is an idle. For example, if there is another STA probe request frame received by the STA during a predetermined time interval, the STA may transmit information including the probe request frame received from another STA in the probe request frame detection field.
- the STA transmits a probe request frame including a probe request frame detection field to the AP (step S910).
- the STA may transmit the probe request frame including information indicating that the probe request frame has been received from the other STA when the probe request frame is transmitted to the AP.
- the probe request frame detection field is an example of a format including information indicating that a probe request frame has been received from another STA.
- the probe request frame detection field may include identifier information of another STA that has transmitted the probe request frame or information indicating that the probe request frame detection field has received a probe request frame from another STA as flag information.
- a probe response frame is received from the AP (step S920).
- the AP may receive a probe request frame transmitted by the STA.
- a probe response frame may be broadcast to a plurality of STAs based on the probe request frame detection field included in the probe request frame transmitted by the STA.
- the probe request frame detection field of the probe response frame may include identifier information of another STA.
- the AP may broadcast a probe response frame to a plurality of STAs.
- FIG. 10 is a conceptual diagram illustrating a scanning method according to an embodiment of the present invention.
- FIG. 10 illustrates a case in which the AP broadcasts a beacon frame instead of a probe response frame.
- the AP may broadcast a beacon frame instead of the probe response frame, and the STA may perform passive scanning based on the received beacon frame.
- the procedure until the STA 2 indicates whether another STA transmits the probe request frame based on the probe request frame detection field when the probe request frame is transmitted is the same as the procedure up to step S730 of FIG. 7.
- the AP may broadcast a beacon frame (step S1000).
- the AP may broadcast a beacon frame if the transmission time of the beacon frame comes before (eg, included) the time for which the terminal monitors the probe response frame (eg, the maximum channel time). If the transmission time of the beacon frame does not come before the time that the terminal monitors the probe response frame, it may transmit a probe response frame as described above.
- a short beacon frame which is shortened to a conventional general beacon frame, may be used or a general beacon frame.
- the short beacon frame may be a frame from which redundant unnecessary information is removed from a medium access control (MAC) header of the frame.
- MAC medium access control
- a short beacon frame may not include information related to the entire BSS in the frame.
- Beacon frame can be transmitted.
- the transmission method may broadcast a probe response frame even when individual request information is included in the first probe request frame and the second probe request frame according to the AP's decision. It is included in the scope of the invention.
- a method of transmitting a beacon frame without broadcasting a probe response frame as shown in FIG. 10 may be applied to a case where a probe response frame is broadcast to a plurality of STAs. For example, when individual request information is not included in probe request frames transmitted by a plurality of STAs, the AP may broadcast probe response frames without having to unicast individual probe response frames to each STA. In this case, the AP may broadcast a beacon frame instead of a probe response frame.
- the AP should transmit the probe response frame including the response to the individual request information to the STA.
- the probe response frame may be transmitted.
- the AP may unicast the probe response frame to the STA that transmits the individual request information and broadcast the beacon frame to the STA that does not transmit the other individual request information.
- the probe response frame may be broadcast at the discretion of the AP. It is included in a range.
- FIG. 11 is a conceptual diagram illustrating a method of determining whether an AP transmits a probe response frame according to an embodiment of the present invention.
- the AP receives information of a probe request frame detection field included in a probe request frame (step S1100).
- the AP may receive a probe request frame from at least one STA.
- the AP may determine whether another STA transmits the probe request frame based on the received probe request frame.
- a probe response frame or beacon frame is broadcasted (step S1120).
- the AP may determine that the plurality of STAs have received the probe request frame based on the determination result of step S1100. In this case, the AP may broadcast a probe response frame or a beacon frame based on the transmission time of the beacon frame.
- the AP when the transmission time of the probe response frame and the transmission time of the beacon frame overlap with the plurality of STAs, the AP may broadcast the beacon frame instead of the probe response frame. For example, if the timing at which the AP transmits a probe response frame and the transmission time of the short beacon frame overlap, the AP may broadcast a short beacon frame instead of the probe response frame. As another example, when a target beacon transmission time (TBTT), which is a transmission time of a general beacon frame, overlaps with a timing for transmitting a probe response frame, the AP may broadcast the general beacon frame instead of the probe response frame.
- TBTT target beacon transmission time
- FIG. 12 is a block diagram illustrating a wireless device to which an embodiment of the present invention can be applied.
- the wireless device 1200 is an STA capable of implementing the above-described embodiment, and may be an AP or a non-AP STA.
- the wireless device 1200 includes a processor 1220, a memory 1240, and an RF unit 1260.
- the RF unit 1260 may be connected to the processor 1220 to transmit / receive a radio signal.
- the processor 1220 implements the functions, processes, and / or methods proposed in the present invention.
- the processor 1220 may be implemented to perform the operation of the wireless device according to the embodiment of the present invention described above.
- the processor 1220 may be configured to include an indicator that a probe request frame has been broadcast from another STA and that a probe request frame has been received from another STA when the probe request frame is broadcast.
- the probe request frame may include a probe request frame detection field as an indicator, and the probe request frame detection field may indicate that a probe request frame has been received from another STA.
- the processor 1220 transmits a beacon frame when the transmission time of the beacon frame overlaps with the transmission time of the probe response frame, and when the transmission time of the beacon frame does not overlap with the transmission time of the probe response frame.
- the probe response frame may be implemented to transmit a probe response frame.
- the processor 1220 may include an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a data processing device, and / or a converter for translating baseband signals and wireless signals.
- the memory 1240 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium, and / or other storage device.
- the RF unit 1260 may include one or more antennas for transmitting and / or receiving a radio signal.
- the above-described technique may be implemented as a module (process, function, etc.) for performing the above-described function.
- the module may be stored in the memory 1240 and executed by the processor 1220.
- the memory 1240 may be inside or outside the processor 1220 and may be connected to the processor 1220 by various well-known means.
Abstract
Description
Claims (12)
- 무선랜에서 액티브 스캐닝 방법에 있어서,
제1 STA(station)으로부터 브로드캐스트된 제1 프로브 요청 프레임을 제2 STA이 수신하는 단계; 및
상기 제2 STA이 제2 프로브 요청 프레임을 브로드캐스트하는 단계를 포함하되,
상기 제2 프로브 요청 프레임은 프로브 요청 프레임 탐지 필드를 포함하고,
상기 프로브 요청 프레임 탐지 필드는 상기 제2 STA이 상기 제1 프로브 요청 프레임을 수신하였음을 지시하는 액티브 스캐닝 방법. - 제1항에서,
상기 제2 프로브 요청 프레임은 상기 제1 STA의 식별자에 관한 정보를 더 포함하는 액티브 스캐닝 방법. - 제1항에 있어서,
상기 제2 STA이 AP(access point)로부터 비콘 프레임 또는 상기 제2 프로브 요청 프레임에 대한 응답인 프로브 응답 프레임을 수신하는 단계를 더 포함하는 액티브 스캐닝 방법. - 제3항에 있어서,
상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일할 경우 상기 프로브 응답 프레임을 브로드캐스트하는 것을 특징으로 하는 액티브 스캐닝 방법. - 제3항에 있어서,
상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일하고 상기 제1 STA 및 상기 제2 STA의 상기 프로브 응답 프레임을 모니터링하는 시간에 상기 비콘 프레임의 전송 시간이 돌아오는 경우, 상기 비콘 프레임을 브로드캐스트하고, 상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일하고 상기 제1 STA 및 상기 제2 STA의 상기 프로브 응답 프레임을 모니터링하는 시간에 상기 비콘 프레임의 전송 시간이 돌아오지 않는 경우, 상기 프로브 응답 프레임을 브로드캐스트하는 것을 특징으로 하는 액티브 스캐닝 방법. - 제5항에 있어서,
상기 제1 STA은 상기 제2 STA으로부터 상기 제2 프로브 요청 프레임을 수신하면 프로브 타이머를 최대 채널 시간으로 설정하는 것을 특징으로 하되,
상기 프로브 타이머는 상기 제1 STA이 스캐닝하는 채널을 이동할지 여부를 설정된 시간을 기준으로 판단하는 액티브 스캐닝 방법. - 무선랜 장치에 있어서, 상기 무선랜 장치는 프로세서를 포함하고,
상기 프로세서는 제1 STA(station)으로부터 브로드캐스트된 제1 프로브 요청 프레임을 제2 STA이 수신하고 상기 제2 STA이 제2 프로브 요청 프레임을 브로드캐스트하도록 구현되되,
상기 제2 프로브 요청 프레임은 프로브 요청 프레임 탐지 필드를 포함하고, 상기 프로브 요청 프레임 탐지 필드는 상기 제2 STA이 상기 제1 프로브 요청 프레임을 수신하였음을 지시하는 무선랜 장치. - 제7항에서,
상기 제2 프로브 요청 프레임은 상기 제1 STA의 식별자에 관한 정보를 더 포함하는 무선랜 장치. - 제7항에 있어서, 상기 프로세서는
상기 제2 STA이 AP(access point)로부터 비콘 프레임 또는 상기 제2 프로브 요청 프레임에 대한 응답인 프로브 응답 프레임을 수신하도록 구현되는 무선랜 장치. - 제9항에 있어서,
상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일할 경우 상기 프로브 응답 프레임을 브로드캐스트하는 것을 특징으로 하는 무선랜 장치. - 제9항에 있어서,
상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일하고 상기 제1 STA 및 상기 제2 STA의 상기 프로브 응답 프레임을 모니터링하는 시간에 상기 비콘 프레임의 전송 시간이 돌아오는 경우, 상기 비콘 프레임을 브로드캐스트하고, 상기 AP는 상기 제1 프로브 요청 프레임 및 상기 제2 프로브 요청 프레임에 대한 응답으로 상기 제1 STA 및 상기 제2 STA에 전송해야 하는 정보가 동일하고 상기 제1 STA 및 상기 제2 STA의 상기 프로브 응답 프레임을 모니터링하는 시간에 상기 비콘 프레임의 전송 시간이 돌아오지 않는 경우, 상기 프로브 응답 프레임을 브로드캐스트하는 것을 특징으로 하는 무선랜 장치. - 제11항에 있어서,
상기 제1 STA은 상기 제2 STA으로부터 상기 제2 프로브 요청 프레임을 수신하면 프로브 타이머를 최대 채널 시간으로 설정하는 것을 특징으로 하되,
상기 프로브 타이머는 상기 제1 STA이 스캐닝하는 채널을 이동할지 여부를 설정된 시간을 기준으로 판단하는 무선랜 장치.
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