WO2014003473A1

WO2014003473A1 - Method for changing aid in wireless lan system

Info

Publication number: WO2014003473A1
Application number: PCT/KR2013/005734
Authority: WO
Inventors: 정양석; 양해석
Original assignee: 주식회사 케이티
Priority date: 2012-06-28
Filing date: 2013-06-27
Publication date: 2014-01-03

Abstract

Disclosed is a method for changing an AID in a wireless LAN system. The method for changing an AID of a terminal by an access point comprises: a step of receiving an AID reassignment frame from the access point; a step of extracting an AID reassignment counter value from the AID reassignment frame; and a step of changing the AID of the terminal to the new AID included in the AID reassignment frame after the beacon periods of the access point indicated by the AID reassignment counter value extracted from the AID reassignment frame reception time have elapsed. Thus, a conflict between AIDs can be prevented.

Description

How to change AID in wireless LAN system

The present invention relates to a method for changing an association ID (AID), and more particularly, to an AID change method for changing an existing AID into a new AID in a WLAN system.

With the development of information and communication technology, various wireless communication technologies are being developed. Among them, wireless local area network (WLAN) is based on radio frequency technology such as personal digital assistant (PDA), laptop computer, portable multimedia player (PMP), etc. It is a technology that allows a user to access the Internet wirelessly at home, a business, or a specific service area by using a portable terminal.

The standard for WLAN technology is being developed as an Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. IEEE 802.11a provides a transmission rate of 54 Mbps using an unlicensed band at 5 GHz. IEEE 802.11b applies a direct sequence spread spectrum (DSSS) at 2.4 GHz to provide a transmission rate of 11 Mbps. IEEE 802.11g applies orthogonal frequency division multiplexing (OFDM) at 2.4 GHz to provide a transmission rate of 54 Mbps. IEEE 802.11n applies multiple input multiple output OFDM (MIMO-OFDM) to provide a transmission rate of 300 Mbps for two spatial streams. IEEE 802.11n supports a channel bandwidth of up to 40 MHz, in which case it provides a transmission rate of 600 Mbps.

As the spread of the WLAN is activated and the applications using the same are diversified, there is an increasing need for a new WLAN technology for supporting a higher throughput than the data processing speed supported by IEEE 802.11n. Very high throughput (VHT) WLAN technology is one of IEEE 802.11 WLAN technologies that have been proposed to support data processing speeds of 1 Gbps or more. Among them, IEEE 802.11ac is being developed as a standard for providing very high throughput in the band below 5 GHz, and IEEE 802.11ad is being developed as a standard for providing very high throughput in the 60 GHz band.

In a system based on such a WLAN technology, an access point (AP) assigns and manages a unique association ID (AID) for each station whenever a station accesses it. In the WLAN system, a case where an AID, which is a station unique number, needs to be changed during operation of an access point and a station may occur. In this case, when reassigning AIDs for the stations, the access point may reassign a new AID to the station, and the station may change the existing AID to the reassigned new AID. In this case, when AIDs for a plurality of stations are reassigned, a time point for changing an existing AID to a new AID that is reassigned may vary from station to station, and thus there is a problem in that collisions between AIDs occur.

An object of the present invention for solving the above problems is to provide a method for changing the AID of a station to prevent a collision between AIDs when changing the AID in the WLAN system.

In accordance with an aspect of the present invention, there is provided a method for changing an AID of a terminal, the method comprising: receiving an AID reassignment frame from an access point, extracting an AID reassignment counter value from the AID reassignment frame, and Changing the AID of the terminal to a new AID included in the AID reassignment frame after the beacon periods of the access point indicated by the extracted AID reassignment counter value are taken from the time of receiving the AID reassignment frame. Steps.

Here, when the AID reassignment counter value extracted in the step of extracting the AID reassignment counter value is 0, changing the AID of the terminal is immediately included in the AID reassignment frame at the time of receiving the AID reassignment frame. The AID of the terminal can be changed to a new AID.

Here, the AID reassignment frame may be received corresponding to the PS-Poll frame transmitted by the terminal to the access point.

Here, when there is at least one terminal to change the AID at the same time with the terminal, the AID reassignment counter value is the listen interval of the terminal and the listen interval of at least one terminal to change the AID at the same time with the terminal. It may be determined in consideration of them together.

Here, the AID reassignment counter value may be configured such that the AID of the terminal is changed after the listen interval having the longest value between the listen interval of the terminal and the listen interval of at least one terminal to change the AID simultaneously with the terminal. Can be.

AID reassignment method of an access point according to an embodiment of the present invention for achieving the above object, generating an AID reassignment frame including a new AID and an AID reassignment count value designating a change point to the new AID. And transmitting the AID reassignment frame to the terminal, wherein the AID reassignment count value includes beacon periods of the access point indicated by the AID reassignment count value from the time of transmitting the AID reassignment frame. Thereafter, the AID may be instructed to change the AID of the terminal to a new AID included in the AID reassignment frame.

Here, when the AID reassignment count value is 0, the AID reassignment count value may instruct to change the AID of the terminal to a new AID immediately at the time of transmitting the AID reassignment frame.

Here, the AID reassignment frame may be transmitted corresponding to the PS-Poll frame received by the access point from the terminal.

Here, when there is at least one terminal to change the AID at the same time with the terminal, the AID reassignment count value is the listen interval of the terminal and the listen interval of at least one terminal to change the AID simultaneously with the terminal. It may be determined in consideration of them.

Here, the AID reassignment count value may be configured such that the AID of the terminal is changed after the listen interval having the longest value between the listen interval of the terminal and the listen interval of at least one terminal that should simultaneously change the AID. Can be.

According to the present invention, it is possible to prevent collisions between AIDs when changing the AIDs for one station or when changing the AIDs for a plurality of stations while all AIDs are in use. In addition, by preventing collisions between AIDs, it is possible to provide stable and reliable network services, and it is possible to prevent waste of costs because there is no need to install an additional access point to secure a separate reserve AID.

1 is a conceptual diagram illustrating an embodiment of a configuration of an IEEE 802.11 WLAN system.

2 is a conceptual diagram illustrating a connection process of a terminal in an infrastructure BSS.

3 is a block diagram illustrating an embodiment of a component of a TIM included in a beacon.

4 is a conceptual diagram illustrating an embodiment of a data transmission process of an access point.

5 is a block diagram illustrating an embodiment of an AID structure.

6 is a block diagram illustrating an embodiment of a frame structure for designating a service type of a terminal.

7 is a conceptual diagram illustrating an embodiment of a structure of a TIM encoded on a block basis.

8 is a conceptual diagram illustrating a process of reallocating an AID for a group.

9 is a flowchart illustrating a method of changing an AID according to an embodiment of the present invention.

10 is a block diagram illustrating an embodiment of an AID reassignment frame.

11 is a conceptual diagram illustrating an AID change process for a plurality of stations.

As the present invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In the following description of the present invention, the same reference numerals are used for the same elements in the drawings and redundant descriptions of the same elements will be omitted.

Throughout the specification, a station (STA) is a physical layer for medium access control (MAC) and wireless medium that conforms to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard. By any functional medium that includes an interface. The station STA may be divided into a station that is an access point (AP) and a station that is a non-access point (STA). A station (STA), which is an access point (AP), may simply be called an access point (AP), and a station (STA), which is a non-AP, may simply be called a terminal.

The station STA may include a processor and a transceiver, and may further include a user interface and a display device. A processor refers to a unit designed to generate a frame to be transmitted through a wireless network or to process a frame received through a wireless network, and performs various functions for controlling a station (STA). A transceiver is a unit that is functionally connected to a processor and is designed to transmit and receive a frame through a wireless network for a station (STA).

An access point (AP) may refer to a centralized controller, a base station (BS), a node-B, an e-node-B, a base transceiver system (BTS), or a site controller, and the like. Some or all of the features may be included.

The terminal may be a wireless transmit / receive unit (WTRU), a user equipment (UE), a user terminal (UT), an access terminal (AT), a mobile station (MS), May refer to a mobile terminal, a subscriber unit, a subscriber station (SS), a wireless device, or a mobile subscriber unit, and some of them. Or all of the functions may be included.

Here, a desktop computer, a laptop computer, a tablet PC, a wireless phone, a mobile phone, a smart phone, and an e-communication capable of communicating with a terminal may be used. book readers, portable multimedia players (PMPs), portable game consoles, navigation devices, digital cameras, digital multimedia broadcasting (DMB) players, digital audio recorders, digital audio players ), A digital picture recorder, a digital picture player, a digital video recorder, a digital video player, and the like can be used.

Referring to FIG. 1, an IEEE 802.11 WLAN system includes at least one basic service set (BSS). BSS means a set of stations (STA 1, STA 2 (AP 1), STA 3, STA 4, STA 5 (AP 2)) that can be successfully synchronized to communicate with each other, the concept of a specific area is no.

BSS can be classified into Infrastructure BSS (Independent BSS) and Independent BSS (IBSS), and BSS 1 and BSS 2 represent Infrastructure BSS. BSS 1 connects a terminal (STA 1), an access point (STA 2 (AP 1)) providing a distribution service and a plurality of access points (STA 2 (AP 1), STA 5 (AP 2)) It may include a distribution system (DS). In BSS 1, an access point STA 2 (AP 1) manages a terminal STA 1.

BSS 2 connects a terminal (STA 3, STA 4), an access point (STA 5 (AP 2)) providing a distribution service and a plurality of access points (STA 2 (AP 1), STA 5 (AP 2)) It may include a distribution system. In BSS 2, an access point STA 5 (AP 2) manages terminals STA 3 and STA 4.

The independent BSS, on the other hand, is a BSS operating in an ad-hoc mode. Since the IBSS does not include an access point, there is no centralized management entity. That is, in the IBSS, terminals are managed in a distributed manner. In IBSS, all terminals may be mobile terminals, and thus, are not allowed to be connected to the distribution system (DS), thereby forming a self-contained network.

The access points STA 2 (AP 1) and STA 5 (AP 2) provide access to the distributed system DS through the wireless medium for the terminals STA 1, STA 3, and STA 4 coupled thereto. . Communication between terminals STA 1, STA 3, and STA 4 in BSS 1 or BSS 2 is generally performed through an access point STA 2 (AP 1) or STA 5 (AP 2), but a direct link (direct link) If the link is configured, direct communication between the terminals STA 1, STA 3, and STA 4 is possible.

The plurality of infrastructure BSSs may be interconnected through a distribution system (DS). A plurality of BSSs connected through a distribution system (DS) is called an extended service set (ESS). Stations included in the ESS may communicate with each other, and the UE may move from one BSS to another BSS while seamlessly communicating within the same ESS.

The distribution system (DS) is a mechanism for one access point to communicate with another access point, whereby the access point transmits frames to, or moves to, another BSS for the terminals that are associated with the BSS it manages. A frame may be transmitted for one arbitrary terminal. In addition, the access point may transmit and receive frames with an external network such as a wired network. Such a distribution system (DS) does not necessarily need to be a network, and there is no limitation on its form as long as it can provide a predetermined distribution service defined in the IEEE 802.11 standard. For example, the distribution system may be a wireless network such as a mesh network or a physical structure that connects access points to each other.

The method of changing an AID according to an embodiment of the present invention to be described below may be applied to the IEEE 802.11 WLAN system described above, and in addition to the IEEE 802.11 WLAN system, a wireless personal area network (WPAN) and a wireless body area network (WBAN). It can be applied to various networks such as.

In order for the STA to transmit and receive data in the intra-structure BSS, the terminal STA must first be connected to the access point AP.

Referring to FIG. 2, the connection process of the STA in the infrastructure BSS is largely 1) a probe step (AP), 2) an authentication step with the detected access point (AP). ) And 3) an association step with an authenticated access point (AP).

The STA may first detect neighboring access points (APs) through a detection process. The detection process is divided into a passive scanning method and an active scanning method. The passive scanning method may be performed by overhearing beacons transmitted by neighboring access points (APs). Meanwhile, the active scanning method may be performed by broadcasting a probe request frame. The AP that receives the probe request frame may transmit a probe response frame corresponding to the probe request frame to the corresponding STA. The STA may know the presence of neighboring access points (APs) by receiving a probe response frame.

Thereafter, the terminal STA may perform authentication with the detected access point AP and may perform authentication with the plurality of detected access points APs. An authentication algorithm according to the IEEE 802.11 standard is divided into an open system algorithm for exchanging two authentication frames and a shared key algorithm for exchanging four authentication frames. Through the process of exchanging an authentication request frame and an authentication response frame based on the authentication algorithm, the terminal STA may perform authentication with the access point AP.

Lastly, the terminal STA selects one of the authenticated access points APs and performs a connection process with the selected access point AP. That is, the terminal STA transmits an association request frame to the selected access point AP, and the access point AP that receives the association request frame receives an association response frame corresponding to the association request frame. frame is transmitted to the corresponding STA. As such, through the process of exchanging the connection request frame and the connection response frame, the STA may perform a connection process with the access point AP.

In the IEEE 802.11 WLAN system, when there is data to be transmitted to the terminal, the access point informs the terminal that there is data to be transmitted using a traffic indication map (TIM) in a beacon frame that is periodically transmitted.

Referring to FIG. 3, the TIM includes an element ID field, a length field, a delivery traffic indication message (DTIM) counter field, a DTIM period field, and a bitmap control. control field and a partial virtual bitmap field.

The length field indicates the length of the information field. The DTIM counter field indicates the number of beacons that appear before the DTIM appears. If the DTIM counter is 0, it indicates that the current TIM corresponds to the DTIM. The DTIM counter field consists of one octet. The DTIM Duration field indicates the number of beacon intervals between successive DTIMs. If all TIMs are DTIMs, the value of the DTIM Duration field is one. The DTIM Duration field consists of one octet.

The bitmap control field consists of one octet, and bit number 0 of the bitmap control field means a traffic indicator bit associated with association ID (AID) 0. If this bit is set to 1 and the value of the DTIM counter field is 0, this indicates that at least one multicast or broadcast frame is buffered at the access point. The remaining seven bits of the bitmap control field form a bitmap offset.

The partial virtual bitmap field consists of 1 to 251 octets, and bit number N has a value between 0 and 2007. Each bit of the partial virtual bitmap field corresponds to a traffic buffered for a particular terminal. If the AID of any terminal is N, if there is no buffered traffic for the arbitrary terminal, bit number N in the partial virtual bitmap field is set to 0, and if there is traffic buffered for the arbitrary terminal Bit number N is set to 1 in the partial virtual bitmap field.

Referring to FIG. 4, the AP may broadcast a beacon periodically and broadcast a beacon including the DTIM at three beacon intervals. The terminals STA 1 and STA 2 of the power save mode (PSM) periodically wake up to receive a beacon, check the TIM or DTIM included in the beacon, and transmit data to the access point to the access point. Check that it is buffered. In this case, when the buffered data is present, the terminals STA 1 and STA 2 remain awake to receive data from the access point AP, and when the buffered data does not exist, the terminals STA 1 and STA 2. ) Returns to the power saving state (ie the doze state).

That is, if the bit in the TIM corresponding to its AID is set to 1, the STA (STA 1, STA 2) is a PS (Power Save) -Poll frame (notifying that it is awake and ready to receive data) Or, transmit a trigger (trigger frame) to the access point (AP), the access point (AP) confirms that the terminal (STA 1, STA 2) is ready for data reception by receiving a PS-Poll frame, Data or an acknowledgment (ACK) may be transmitted to the terminals STA 1 and STA 2. When the ACK is transmitted to the terminals STA 1 and STA 2, the access point AP transmits data to the terminals STA 1 and STA 2 at an appropriate time. On the other hand, when the bit in the TIM corresponding to its own AID is set to 0, the terminals STA 1 and STA 2 return to the power saving state.

The TIM (or DTIM) included in the beacon may simultaneously set bits for a plurality of terminal AIDs. Therefore, after the access point broadcasts the beacon, a plurality of terminals whose bits corresponding to their AIDs are set to 1 simultaneously transmit the PS-Poll to the access point. At this time, a competition for accessing a wireless channel for transmitting PS-Poll frames between a plurality of terminals is intensified, and a collision between terminals occurs due to a hidden node problem, which is a problem of a WLAN system. do.

For example, such a phenomenon may occur frequently in a WLAN service supporting thousands of low power sensor terminals. In this case, the terminal may continue to wake up to complete the reception of the data, or the power consumption problem may appear seriously because the retransmission of the PS-Poll frame not transmitted due to the collision must be repeatedly performed.

FIG. 5 is a block diagram showing an embodiment of an AID structure, and FIG. 6 is a block diagram showing an embodiment of a frame structure for designating a service type of a terminal.

If there are a large number of terminals that are serviced through one access point, and these terminals can be grouped with similar features, the access point may group and manage the AIDs of the terminals.

Referring to FIG. 5, the AID structure includes a page ID field, a block index field, a sub-block index field, and a STA bit index field. That is, AIDs may be managed in groups layered by page / block / sub-block units.

Referring to FIG. 6, the terminal may designate a service type in an association request frame and transmit it to an access point. The service type may include a low power terminal type, a terminal type having a channel access priority, a general terminal type, and the like.

That is, the terminal may transmit the access request frame in which the service type is specified to the access point, and the access point may designate a group as a page / block / sub-block suitable for the service type and allocate an AID according to the designated group.

FIG. 7 is a conceptual diagram illustrating an embodiment of a structure of a TIM encoded in block units.

Referring to FIG. 7, a partial virtual bitmap field includes at least one block (block L, block M, ..., block P) field. One block field includes a block control field, a block offset field, a block bitmap field, and a sub-block field having various sizes. The sub-block field includes at least one sub-block bitmap (sub-block bitmap1, sub-block bitmap2, ..., sub-block bitmap M) field.

The block control field indicates the encoding mode (ie, block bitmap mode, single AID mode, OLB (offset + length + bitmap) mode, inverse mode) of the TIM. Indicates. The block offset field indicates an offset value of the encoded block. The block bitmap field indicates a bitmap indicating a sub-block in which an AID bit is set among sub-blocks within a block indicated by the block offset. The sub-block field indicates a bitmap for the AID in the sub-block.

Referring to FIG. 8, while the access point AP groups and manages the stations SAT 1, STA 2, and STA 3, traffic of a specific period is increased so that the stations SAT 1, STA 2, STA are increased. If the need to change the group containing 3) occurs, the access point (AP) sends an AID reassign frame after transmitting the DTIM or after receiving the PS-Poll from the station (STA). Can be sent to.

That is, the access point AP may manage station 1 (SAT 1), station 2 (STA 2), and station 3 (STA 3) as a group, and the stations (SAT 1, STA 2, STA 3) May have PID 1 which is a group ID. If the traffic for Group 1, which includes stations SAT 1, STA 2, and STA 3, has increased, then the access point (AP) may select station 2 (STA 2) and station 3 (STA 4) from other groups (e.g., , AID reassignment frames may be transmitted to station 2 (STA 2) and station 3 (STA 3) for management as group 2). Upon receiving the AID reassignment frame, the station 2 (STA 2) and the station 3 (STA 3) may change their group ID from PID 1 to PID 2.

On the other hand, the access point may allocate the AID of the group according to the characteristics of the station for each station requesting access, and can accommodate and operate as many stations as the maximum assignable AID. After all, if all AIDs are in use, or if all AIDs for a group (i.e., the number of AIDs is predetermined for load balancing, etc. for each group) are in use, or if AID change is required for other reasons, The AID change must be made at the same time. However, since the listen interval values of the stations are different and the waking times are also different, the AID cannot be changed at the same time, and thus an AID collision occurs.

Referring to FIG. 9, the access point 10 may transmit a beacon including a TIM or a DTIM in a broadcasting manner (S100). The station 1 20 among the

stations

20 and 30 may first wake up from the power saving mode and transmit the PS-Poll to the access point 10 (S101).

Upon receiving the PS-Poll of the station 1 20, the access point 10 may generate an AID reassignment frame (S102). That is, when the AIDs of the

stations

20 and 30 are to be changed, the access point 10 may generate an AID reassignment frame when receiving the PS-Poll from the station 1 20 or the station 2 30. Can be.

The AID reassignment frame may include a new AID to be changed and an AID reassignment counter value that designates when to change the new AID. The AID reassignment counter indicates a time point of changing an existing AID to a new AID (that is, a new AID included in an AID reassignment frame), and refers to the number of beacon periods of the access point 10. For example, if the AID reassignment counter value is 5, this indicates to change to a new AID after five beacon cycles from the time the AID reassignment counter is received. When the reallocation counter is received, it indicates to change to a new AID.

Meanwhile, when the AIDs of the station 1 20 and the station 2 30 are to be changed at the same time, the access point 10 considers the listen interval of the station 1 20 and the listen interval of the station 2 30. You can set the AID reassignment counter value. That is, the access point 10 may set an AID reassignment counter value to change to a new AID after the listen interval having the longest value between the listen interval of the station 1 20 and the lease interval of the station 2 30.

For example, if the remaining listen interval of station 1 (20) is 5 and the remaining interval of station 2 (30) is 10 at the present time, the access point 10 associates stations 1 (20) and station 2 (30). AID reassignment counter value can be set to 10.

10 is a block diagram illustrating an embodiment of an AID reassignment frame.

Referring to FIG. 10, a body of an AID reassignment frame may include a category field, an action value field, and an AID reassignment element field. Here, the category field may have a size of one octet, and the action value field may have a size of one octet.

The AID Reassignment Element field may have a size of 6 octets and includes an Element ID field, a length field, a new AID value field, and an AID reassign count field. can do. The element ID field may have a size of one octet and the length field may have a size of one octet. The new AID value field may indicate an AID value to be changed and may have a size of 2 octets. The AID reassignment counter field may indicate a time to change to a new AID, and may have a size of 2 octets.

Here, the configuration of the AID reassignment frame is not limited to the frame illustrated in FIG. 10, and may be configured of various types of frames.

Referring back to FIG. 9, the access point 10 may transmit an AID reassignment frame to the station 1 20 (S103). After transmitting the AID reassignment frame (or at the same time as transmitting the AID reassignment frame), the access point 10 reassigns the AID reassignment for the access point having the AID reassignment counter value included in the AID reassignment frame as an initial value. The counter may be started (S104). The AID reassignment counter for the access point is a counter used inside the access point 10, and decrements by one every time the beacon is transmitted and expires when it reaches zero. If the AID reassignment counter for the access point becomes zero, from this point on, the access point 10 applies a new AID for that station.

Meanwhile, the access point 10 may generate an AID reassignment frame even when the PS-Poll is not received from the station 1 20. That is, when the TIM bitmap corresponding to the AID of the station 1 20 is set and the beacon is transmitted by broadcasting, the access point 10 may generate an AID reassignment frame, and may define a predefined time (eg, For example, after the SIFS, etc., the AID reassignment frame may be transmitted to the station 1 (20).

Alternatively, when receiving a specific frame requesting AID reassignment from station 1 (20), the access point 10 may generate an AID reassignment frame, and the predefined time (e.g., SIFS, etc.) After that, the AID reassignment frame may be sent to station 1 (20).

Here, the station 1 20 that receives the AID reassignment frame may transmit an ACK frame, which is a response to the reception of the AID reassignment frame, to the access point 10.

Upon receiving the AID reassignment frame, the station 1 20 may extract an AID reassignment counter value from the AID reassignment frame (S105). In this case, when the extracted AID reassignment counter value is 0, the station 1 20 may immediately change the existing AID to a new AID (ie, a new AID included in the AID reassignment frame).

Meanwhile, when the extracted AID reassignment counter value is not 0, the station 1 20 may start an AID reassignment counter for station 1 having the AID reassignment counter value as an initial value (S106). The AID reassignment counter for station 1 is a counter used inside station 1 (20), where station 1 (20) decrements the AID reassignment counter by one each time it receives a beacon, or a beacon period (e.g., , AID reassignment counter can be decremented by 1 every 100ms).

Thereafter, the access point 10 may transmit the beacon in a broadcasting manner according to the beacon period (S107). After transmitting the beacon (or at the same time as transmitting the beacon), the access point 10 may decrease the AID reassignment counter by one (S108). The station 1 20 may decrease the AID reassignment counter by 1 when the beacon is received or when the beacon period has passed (S109).

The station 2 30 may wake up from the power saving mode and transmit the PS-Poll to the access point 10 (S110). Upon receiving the PS-Poll of the station 2 30, the access point 10 may transmit an AID reassignment frame including the AID reassignment counter value at the present time to the station 2 30 (S111).

Upon receiving the AID reassignment frame, the station 2 30 may extract an AID reassignment counter value from the AID reassignment frame (S112). In this case, when the extracted AID reassignment counter value is 0, the station 2 30 may immediately change the existing AID to a new AID (ie, a new AID included in the AID reassignment frame).

Meanwhile, when the extracted AID reassignment counter value is not 0, the station 2 30 may start an AID reassignment counter for station 2 having the AID reassignment counter value as an initial value (S113). The AID reassignment counter for station 2 is a counter used inside station 2 (30), where station 2 (30) decrements the AID reassignment counter by one each time it receives a beacon, or a beacon period (e.g., , AID reassignment counter can be decremented by 1 every 100ms).

Thereafter, the access point 10 may transmit the beacon in a broadcasting manner according to the beacon period (S114). The access point 10 may decrement the AID reassignment counter by one after transmitting the beacon (or at the same time as transmitting the beacon), and apply a new AID when the AID reassignment counter becomes zero ( S115). The station 1 20 may decrease the AID reassignment counter by 1 when the beacon is received or when the beacon period has passed, and may change the existing AID to the new AID when the AID reassignment counter reaches 0 (S116). ). The station 2 30 may decrease the AID reassignment counter by 1 when the beacon is received or when the beacon period has passed, and may change the existing AID to the new AID when the AID reassignment counter reaches 0 (S117). ).

That is, the AID reassignment counter values of the access point 10 and the

stations

20 and 30 may both be zero at a time when any beacon is transmitted (or any beacon period), and at that time, the access point 10 may apply the new AID to the

stations

20, 30, and the

stations

20, 30 may change the existing AID to the new AID.

Referring to FIG. 11, when an AID of a station 1 (STA 1) and a station 2 (STA 2) is to be changed at the same time, the access point AP may generate an AID reassignment frame. The AID reassignment frame may include a new AID and an AID reassignment counter indicating when to change a new AID.

If it is desired to change the AID of the station 1 (STA 1) from 1000 to 2000, the access point AP may determine the new AID included in the AID reassignment frame for the station 1 STA1 as 2000. If the AID of the station 2 (STA 2) is to be changed from 2000 to 1000, the access point AP may determine the new AID included in the AID reassignment frame for the station 2 (STA 2) as 1000.

When determining the AID reassignment counter, the access point AP may consider the listen interval of station 1 STA 1 and the listen interval of station 2 STA 2. In this case, the access point AP may determine the listen interval having the longest value between the listen interval of the station 1 (STA 1) and the listen interval of the station 2 (STA 2) as the AID reassignment counter. That is, because the listen interval of station 1 (STA 1) is 5 and the listen interval of station 2 (STA 2) is 30, the access point (AP) is responsible for resetting the AID for stations 1 (STA 1) and station 2 (STA 2). The AID reassignment counter included in the allocation frame may be determined to be 30.

According to this process, the AID reassignment frame for station 1 (STA 1) may have 2000 as the new AID and 30 as the AID reassignment counter. The AID reassignment frame for station 2 may have 1000 as the new AID and 30 as the AID reassignment counter.

Station 1 (STA 1) may wake up from the power saving mode and send the PS-Poll to the access point 10. When the PS-Poll is received from the station 1 (SAT 1), the access point (AP) may generate the above-mentioned AID reassignment frame (new AID: 2000, AID reassignment counter: 29), and generate the generated AID. The reassignment frame may be sent to station 1 (STA 1). Here, since one beacon has been transmitted (that is, one beacon period has passed), the AID reassignment counter value is set to 29 with 1 decreased. The station 1 (STA 1) receiving the AID reassignment frame may transmit an ACK frame to the access point (AP), and set the AID reassignment counter value 29 included in the AID reassignment frame to an initial value to reset the AID. The allocation counter can be started. That is, the station 1 STA 1 may decrease the AID reassignment counter value by 1 every beacon period (or when the beacon is transmitted).

Thereafter, the AP may transmit a beacon according to the beacon period. Station 2 (STA 2) may wake up from the power saving mode and send the PS-Poll to the access point 10. When the PS-Poll is received from the station 2 (SAT 2), the access point (AP) may generate the above-mentioned AID reassignment frame (new AID: 2000, AID reassignment counter: 4), and generate the generated AID. The reassignment frame may be sent to station 2 (STA 2). Here, since 26 beacons have been transmitted (that is, 26 beacon cycles have passed), the AID reassignment counter value is set to 4 with 26 decremented. The station 2 (STA 2) receiving the AID reassignment frame may transmit an ACK frame to the access point (AP), and set the AID reassignment counter value (4) included in the AID reassignment frame to an initial value to reset the AID. The allocation counter can be started. That is, station 2 (STA 2) may decrease the AID reassignment counter value by 1 every beacon period (or when the beacon is transmitted).

Thereafter, the AP may transmit a beacon according to the beacon period, and if additional four beacons are transmitted (that is, four beacon periods have passed), the station 1 (STA 1) and the station 2 (STA) The value of the AID reassignment counter for 2) is zero. At the time when the value of the AID reassignment counter becomes zero, the access point AP may set the AID of station 1 (STA 1) to 2000 and set the AID of station 2 (STA 2) to 1000. In addition, station 1 (STA 1) may change the AID from 1000 to 2000, and station 2 (STA 2) may change the AID from 2000 to 1000.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims

A method of changing an association ID (AID) of a terminal,

Receiving an AID reassignment frame from an access point;

Extracting an AID reassignment counter value from the AID reassignment frame; And

After the beacon periods of the access point indicated by the extracted AID reassignment counter value are taken from the time point at which the AID reassignment frame is received, the AID of the terminal is changed to a new AID included in the AID reassignment frame. AID change method of a terminal, characterized in that it comprises a step of.
The method according to claim 1,

If the AID reassignment counter value extracted in the step of extracting the AID reassignment counter value is 0,

The changing of the AID of the terminal comprises changing the AID of the terminal to a new AID included in the AID reassignment frame at the time of receiving the AID reassignment frame.
The method according to claim 1,

The AID reassignment frame is the AID change method of the terminal, characterized in that received in response to the PS (Power Save) -Poll frame transmitted to the access point.
The method according to claim 1,

If there is at least one terminal to change the AID at the same time with the terminal,

The AID reassignment counter value is determined in consideration of a listen interval of the terminal and a listen interval of at least one terminal to change AID simultaneously with the terminal.
The method according to claim 4,

The AID reassignment counter value is such that the AID of the terminal is changed after the listen interval having the longest value between the listen interval of the terminal and the listen interval of at least one terminal that should change the AID simultaneously with the terminal. Method for changing the AID of the terminal, characterized in that configured.
An access point reassigns an AID (association ID) of a terminal.

Generating an AID reassignment frame including a new AID and an AID reassignment count value specifying a time of change to the new AID; And

Transmitting the AID reassignment frame to the terminal;

The AID reassignment count value is a new AID included in the AID reassignment frame after the beacon periods of the access point indicated by the AID reassignment count value are taken from the time of transmitting the AID reassignment frame. AID reassignment method of an access point, characterized in that the instruction to change the AID of the terminal.
The method according to claim 6,

If the AID reassignment count value is 0,

The AID reassignment count value indicates that the AID reassigns the AID of the terminal to a new AID immediately when the AID reassignment frame is transmitted.
The method according to claim 6,

The AID reassignment frame is an AID reassignment method of an access point, characterized in that transmitted by the access point corresponding to the PS (Power Save) -Poll frame received from the terminal.
The method according to claim 6,

If there is at least one terminal to change the AID at the same time with the terminal,

The AID reassignment count value is determined in consideration of a listen interval of the terminal and a listen interval of at least one terminal to change the AID simultaneously with the terminal. .
The method according to claim 9,

The AID reassignment count value may be changed so that the AID of the terminal is changed after a listen interval having the longest value between a listen interval of the terminal and a listen interval of at least one terminal that should change AID simultaneously with the terminal. AID reassignment method of an access point, characterized in that configured.