KR100918238B1 - Method for wireless local area network communication using adaptive grouping - Google Patents

Abstract

The present invention discloses a wireless LAN communication method. The present invention groups the communication terminals included in the cell area, calculates the collision rate and the transmission rate of the data transmitted in the transmission time of each group, and accordingly, the group having a high collision rate is adaptive to a large number of communication terminals. By dividing into lower groups, and having a low transmission rate due to the small number of communication terminals, a group having a low transmission rate can be integrated with a neighboring group, thereby maximizing transmission efficiency even when the number of communication terminals is not only known correctly, but also unknown. .

Description

Wireless communication method using adaptive grouping {Method for wireless local area network communication using adaptive grouping}

The present invention relates to a WLAN communication method, and more particularly, to a WLAN communication method for adaptively grouping communication terminals in a cell to perform communication.

In general, a wireless local area network (WLAN) refers to a short range wireless network conforming to the IEEE 802.11 standard. In the current 2.4GHz (Giga Herz) band, the frequency hopping spread spectrum (Frequency Hopping Spread Spectrum (FHSS), Direct Sequence Spread Spectrum (DSSS) or Infrared Rays (IR) 802.11b supporting data rates of up to 11 Mbps (Mega Bits Per Second), orthogonal frequency division multiplexing (Orthogonal Frequency Division Multiplexing) in 5 GHz 802.11a supporting a data rate of up to 54 Mbps, Quality of Service; 802.11e for guaranteeing QoS, 802.11f for Inter Access Point protocol, 802.11g supporting up to 54Mbps data rate by orthogonal frequency division multiplexing in 2.4GHz band, and transmit power control ; 802.11h, which supports TPC) and Dynamic Frequency Selection (DFS), and 802.11i with improved security, have been decided or standard Under discussion for information. Other meetings include 802.11 5GHz Globalization Special Group (5GSC) and 902.11 Wireless Lan Next Generation (WNG), which discuss the next generation of wireless LANs.

The IEEE 802.11 network has a basic service set (BSS) consisting of a plurality of communication terminals communicating with each other based on an access point (AP), and BSS is a direct communication between communication terminals without an AP. There is an independent BSS that does this, and an infrastructure BSS where the AP is used in all communication processes.

1 is a diagram illustrating a general configuration of a wireless local area network.

As shown in FIG. 1, a wireless LAN is a network capable of wirelessly transmitting and receiving data between communication terminals within a certain distance without wiring to a floor, as in a wired Ethernet. The communication terminals can move freely because they communicate wirelessly.

As shown, an infrastructure BSS may be combined with other infrastructure BSSs to form an extended BSS. In the infrastructure BSS, communication between communication terminals must always go through an AP. That is, when the first communication terminal transmits a frame to the second communication terminal, the first communication terminal first transmits the frame to the AP, and the AP transmits the received frame to the second communication terminal again. The second communication terminal receiving the frame transmits an acknowledgment (Ack) frame for the received frame to the first communication terminal, even in this case, 2 hops through the AP.

Communication in the infrastructure BSS can be classified into two types: distributed coordination function (hereinafter referred to as DCF) mode and point coordination function (hereinafter referred to as PCF) mode. In the PCF mode, a special communication terminal called a point coordinator enables data transmission between communication terminals without contention for a medium, and the point coordinator mainly plays a role of the AP. PCF mode has the advantage that there is no competition for the media, but it is currently hardly implemented due to polling and inefficiency of the response method.

In independent BSS, access to the wireless medium operates in DCF mode. DCF is different from wired Ethernet using Carrier Sense Multiple Access with Collision Detection (CSMA / CD), so that the DCF is a Carrier Sense Multiple Access with Collision Avoidance for transmission efficiency. Hereinafter referred to as CSMA / CA). The CSMA / CA method first checks whether a channel is empty and transmits data when the channel is empty. Meanwhile, in order to prevent frame collision between communication terminals, the 802.11 DCF protocol adopts a method of transmitting a frame after a random delay time (Back Off) has elapsed even if the channel is empty.

The conventional IEEE 802.11 protocol operates efficiently when the number of terminals is about several tens in a cell and handoff does not occur frequently. However, if the number of terminals increases by more than a few dozens, collisions occur frequently during data transmission, and if the terminals move frequently, the transmission performance of the existing 802.11 wireless local area network (WLAN) may be reduced due to the frequent association procedure. Decrease sharply. In the past, the following two methods have been proposed to solve this high collision problem.

The first is a hardware method of dividing a cell into several small cells. However, this method has a disadvantage in that the installation cost is high because the AP must be installed in every small cell. In addition, when the UEs move because the radius of the cell decreases, the registration load increases due to more frequent handoff.

The second is a software method that uses a grouping technique called Group Coordination Function (GCF) or Group Based Distributed Coordination Function (GB-DCF), which is an intermediate form between 802.11 DCF mode and PCF mode. In these modes, terminals in a cell are divided into groups according to a medium access control (MAC) address, and the AP periodically transmits a beacon message to designate when to transmit each group. During the designated group transmission time, only terminals belonging to this group can transmit data competitively by the DCF scheme.

More specifically, only a method of statically determining the total number of groups in the GCF mode for distributing high collisions has been proposed. That is, by determining the number of terminals communicating in the 802.11 cell to determine the number of groups that can operate at the optimal performance. It is assumed that the number of terminals is accurately determined by registration.

That is, it is analytically calculated as the most efficient when eight terminals compete in one group. When the total number of registered terminals is x , the total number of groups is calculated as x / 8. When the number of groups is determined, the group address of each terminal is calculated based on the individual MAC address and the modulo value transmitted by the beacon message transmitted by the AP. When the number of groups is calculated as 8, the beacon message transmits 8 as a modulo value, and the group address of each terminal becomes "MAC address modulo 8". For reference, the modulo operator divides operands and returns the remaining values. Only terminals whose "MAC address modulo 8" value is the same as the group address specified in the beacon message operate in DCF mode and transmit data until the next beacon message is transmitted.

However, the conventional technology statically determines the number of groups assuming that the WLAN is registered by the registration procedure when operating in the GCF mode, but this assumption has the following two problems.

First, there is a problem in that the number of terminals existing in a cell must be accurately known. In a wireless LAN where security is not important, all terminals may be used without registering through a registration procedure. In addition, when the terminal moves at a high speed, it may not be registered to reduce the load due to registration. In a WLAN without such an explicit registration procedure, the total number of terminals in a cell cannot be determined and thus an optimal number of groups cannot be determined.

Second, when the number of groups is statically determined, the number of terminals belonging to an arbitrary group is not uniform, resulting in a problem of degrading performance. That is, when determining the number of groups and determining the group belonging to the MAC address of the terminal, there is a problem that the terminal belongs to too many or too few in any group. In this case, there is a problem in that the transmission efficiency of a specific group is degraded due to frequent collisions in the group to which the terminal belongs too much. On the contrary, if the number of terminals is small, there is a problem that the group time is wasted.

Technical problem to be solved by the present invention is a WLAN communication method that can maximize the communication efficiency by adaptively grouping the communication terminals in the cell area even if the number of each communication terminal that is a communication terminal in the cell area continuously To provide.

The present invention for solving the above-mentioned problem, basically improve the communication efficiency by subdividing any group adaptively or integrating a plurality of dormant groups into one group according to the collision rate measured in the AP. In order to adaptively change the number of groups, the range of the group is adaptively adjusted by using a MAC subnet mask of a concept such as an 802.11 MAC address and a subnet mask of IP.

In the WLAN communication method of the present invention for achieving the above technical problem, (a) the AP is a beacon message including the group address and the subnet mask of the group (selection group) selected by the AP to the communication terminals in its cell area; Transmitting; (b) when the communication terminals receiving the beacon message perform an AND operation on their MAC address and the subnet mask and compare the group address with each other to transmit data to the AP; (c) the AP dividing the selection group into subgroups according to the collision rate or transmission rate of the data received from the communication terminals, or generating the upper group by merging the selection group and the neighbor group; And (d) performing steps (a) to (c) described above for the lower groups or the upper groups.

In addition, in step (c), when the collision rate of the data transmitted by the communication terminals is equal to or greater than the threshold collision rate, the group corresponding to the group address may be divided into subgroups.

In addition, step (c) described above may include: (c1) generating a subnet mask of subgroups; (c2) generating group addresses of subgroups; And (c3) registering, in subgroups, group information including a subnet mask and a group address in a group information list.

In addition, in the above-described step (c1), the subnet masks of the lower groups may be generated by setting the upper bits of the most significant bit set to 1 among the bits of the subnet mask of the group indicated by the group address to 1.

In addition, the above-described subgroups are composed of a first subgroup and a second subgroup, and the group address of the first subgroup in step (c2) is the subnet mask generated in step (c1) of the bits of the group address to be divided. It can be generated by setting the bit corresponding to the most significant bit of to 1.

In addition, the above-described second subgroup may use the group address of the selection group.

In addition, in the step (c) described above, when the transmission rate of the data transmitted by the communication terminals is less than the threshold transmission rate, the higher group may be generated by merging the selection group and the neighboring group.

In addition, the step (c) described above, (c4) generating a subnet mask of the upper group; (c5) searching for neighboring groups to be integrated with the selection group to form a higher group; And (c6) generating a group address of the upper group.

In addition, in the above-described step (c4), the most significant bit set to 1 of the bits of the subnet mask of the selection group may be set to 0 to generate the subnet mask of the higher group.

Also, in the above-described step (c5), the bits corresponding to the bits set to 1 in the subnet mask of the upper group generated in the step (c1) may search for groups having the same group address as the selection group.

In addition, in the above-described step (c6), the group address of the upper group may be generated by performing an AND operation on the selection group address and the subnet mask of the upper group generated in the step (c4).

The present invention groups the communication terminals included in the cell area, calculates the collision rate and the transmission rate of the data transmitted in the transmission time of each group, and accordingly, the group having a high collision rate is adaptive to a large number of communication terminals. By dividing into lower groups, and having a low transmission rate due to the small number of communication terminals, a group having a low transmission rate can be integrated with a neighboring group, thereby maximizing transmission efficiency even when the number of communication terminals is not only known correctly, but also unknown. .

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

As described above, the present invention periodically allocates a group by transmitting a beacon message to communication terminals of users located in the cell area. Unlike the prior art, the beacon message further includes a group address field and a subnet mask field, and the communication terminal identifies the group to which it belongs by examining the group address field and the subnet mask field in the received beacon message, Communicate through the AP at the allotted time.

2 is a diagram showing the structure of a beacon frame periodically transmitted from the AP to the user terminal according to an embodiment of the present invention. Referring to FIG. 2, a beacon frame includes a frame control field of 2 bytes, a duration (ID) field of 2 bytes, a destination address field of 6 bytes, a source address field of 6 bytes, a BSSID field of 6 bytes, a sequence control field of 2 bytes, and 2 bytes. It consists of a group address field, a subnet mask field of 2 bytes, a frame body field of up to 2,312 bytes, and a frame check sequence (FCS) of 4 bytes.

The frame control field is a protocol field in which a protocol version such as the 802.11 MAC version is recorded, a type and floating field for distinguishing the type of frame being used, and ToDS, FromDS, additional fragments, and retries storing various parameters for frame control. , Power management, additional data, power management, WEP, sequence and so on.

The Duration (Duration / ID) field is used for various purposes and is used in the form of a frame transmitted during a Network Allocation Vector (NAV) setting or a Contention Free Period (CFP) or a PS-irradiation frame.

The sequence control field is used to discard fragmentation reassembly and duplicate frames, and is composed of a 4-bit fragmentation number field and a 12-bit sequence number field.

The frame body field, called a data field, supports a 2,312-byte frame body to accommodate overhead (8 bytes) by the SEP, which can carry up to 2,304 bytes of data.

The FCS is used to check the integrity of a frame received from a specific terminal.

Meanwhile, when the group address field and the subnet mask field added in the present invention are described, the present invention designates the number of groups and the group address of the terminal by these two fields. Each terminal calculates a group address by ANDing its subnet mask and its MAC address of the beacon message shown in FIG. 2, and identifies the group to which it belongs by comparing with the group address transmitted in the beacon message.

For example, assuming that the MAC address is 8 bits long and the subnet mask is 00000001, the result of ANDing the subnet mask with the MAC address is 00000000 (corresponding to group 0) or 00000001 (corresponding to group 1). The communication terminal compares this result with the group address field, and if the group address and the AND operation result are identical, the communication terminal transmits the data through the AP because the data transmission time is allocated to the group to which the communication terminal belongs. If not, wait until the next beacon message is received because it is not the data transmission time allocated to the group to which it belongs. For convenience of explanation, it is assumed that all MAC addresses are 8 bits long.

The present invention can adjust the number of groups by adjusting the number of 1s in the subnet mask. That is, the size of the group is adaptively adjusted through subnetting or supernetting according to the collision level of the group. If the collision level of any group is higher than the threshold, the group is divided into two groups. If the number of transmissions of adjacent groups is smaller than the threshold, supernetting is used to combine adjacent groups into one large group.

For example, when the subnet mask is set to 00000001 and the communication terminals in the cell area are divided into two groups, when the collision level of the group 1 is higher than the threshold, the group 1 may be divided into two small groups. That is, group 0 may be designated as a group address 0 and a subnet mask 00000001, but group 1 to which communication terminals having the least significant bit of the MAC address 1 may be subnetted into two groups. The two groups divided from group 1 are designated as subnet mask 00000011 and group address 1, and subnet mask 00000011 and group address 3, respectively. That is, the communication terminals having the least significant bit of the MAC address of 1 are divided into two groups of the least significant bit of the MAC address of 0 or 1.

In the same way, small groups of two or multiples of two are combined into one group. For example, when the number of terminals belonging to groups 0, 2, 4, and 6 is small when the subnet mask is 00000111, these groups may be integrated into the subnet mask 00000001 and the group address 0. Of course, groups 1, 3, 5, 7 are still referred to as subnet mask 00000111 and group addresses 1, 3, 5, 7.

3A and 3B are flowcharts illustrating an adaptive grouping process performed in the preferred embodiment of the present invention. Referring to FIG. 3A and FIG. 3B, a WLAN communication method using adaptive communication terminal grouping according to an exemplary embodiment of the present invention will be described. First, the AP allocates a communication time from group lists generated through the following processes. A group to be selected is selected (S300). The selection of the group is made by pre-set rules.

After the group is selected, the AP generates a beacon message including a group address and a subnet mask of the selected group (hereinafter referred to as a selection group) and transmits the beacon message to communication terminals in its cell area (S304).

 Communication terminals receiving the beacon message transmitted by the AP reads the group address field and the subnet mask field included in the beacon message (S310).

Thereafter, the communication terminal performs an AND operation on the subnet mask and its MAC address to identify a group to which it belongs (S312), and, as a result of the AND operation, that is, the group with the group address read in step S310. In comparison, if the operation result and the group address are not the same, the apparatus waits until the next beacon message is received (S314).

As a result of the comparison in the step S314, if the operation result (the group to which it belongs) is the same as the group address, data is transmitted according to the conventional DCF scheme (S316).

Meanwhile, the AP, which transmits the beacon message, receives data from the communication terminals, checks whether a collision is detected during data reception (S320), and calculates a collision rate when the collision is detected (S322). Since the collision rate calculation method is the same as the collision rate calculation method generally performed in a communication network, a detailed description thereof will be omitted.

On the other hand, the AP checks whether the reception of data from the communication terminals is successful (S324), and if the data reception is successful (S326). The method of calculating the transmission rate is also the same as the method of calculating the transmission rate generally performed in a communication network, and thus detailed description thereof is omitted.

Thereafter, the AP checks whether the transmission time allocated to the selection group has ended and, if the transmission time has not yet expired, proceeds to step S320 described above (S328).

When the transmission time for the selection group has ended, it is examined whether the collision rate occurring in the selection group is greater than or equal to the threshold collision rate. If the collision rate is smaller than the threshold collision rate, the process proceeds to step S350.

In step S330, if the collision rate is greater than or equal to the threshold collision rate, a new group address and a subnet mask are generated for the selection group to perform subnetting to divide the selection group to generate subgroups, and the transmission process for the selection group is terminated. (S340).

On the other hand, when the collision rate is less than the threshold collision rate, the AP examines whether the transmission rate is less than the threshold transmission rate and whether there is a mergeable group among adjacent groups, so that even if the transmission rate is higher than the threshold transmission rate or the transmission rate is lower than the threshold transmission rate, If there is no mergeable group among the groups adjacent to the corresponding group, the transmission process for the selected group ends (S350).

 However, if the transmission rate is less than the threshold transmission rate and there is a group that can be merged among the groups adjacent to the group, the selection group may be supernetted by creating a new group address and subnet mask for the selection group. The parent group is generated by merging with the neighbor group (S360).

4A is a flowchart illustrating a process of dividing a group in more detail in operation S340 described above. FIG. 4B is a diagram illustrating an example of software implementation of the process illustrated in FIG. 4A. FIG. 3 is a diagram conceptually illustrating a process of dividing a group in operation S340.

First, referring to FIGS. 4A and 4B, each group information includes a group address and a subnet mask, and when the collision rate is determined to be equal to or greater than the threshold collision rate in operation S330 described above, the group information is divided from the selected group. A new subnet mask of the lower groups to be generated is generated (S341). The new subnet mask is generated by setting the high order bit of the most significant bit set to 1 in the subnet mask corresponding to the selection group to 1. For example, if the subnet mask and the selection group address of the selection group are 00000011 and 00000001, respectively, 00000111 is generated as a new subnet mask.

Thereafter, the AP generates group addresses of subgroups in which the current group is divided (S343). At this time, the selection group is divided into first and second subgroups, the first subgroup uses the group address of the selection group as it is, and the address of the second subgroup is newly generated. In the above example, the address of the second subgroup to be newly generated is generated by setting the bit corresponding to the bit newly set to 1 in the new subnet mask among the bits of the group address of the selection group to 1. For example, in the above example, since the group address of the selection group is 00000001, the group address (00000101) of the second subgroup to be divided and generated is generated by setting the third bit to 1 at the end newly set in the subnet mask.

When the group address of the second subgroup is newly generated, the AP registers the group information of the first subgroup in the group list (S345). In the above example, the group information (00000111,00000001) of the first subgroup is newly registered in the group information list in which group information consisting of (subnet mask, group address) is registered.

Thereafter, the AP registers group information of the second subgroup in the group information list (S347). In the above example, group information of (00000111,00000101) is newly registered in the group information list as group information of the second subgroup.

Finally, the AP deletes the group information of the selected group that has been previously registered as (00000011,00000001) from the group information list (S349).

As described above, a series of processes for dividing groups by subnetting are conceptually illustrated in FIG. 4C. As shown in FIG. 4C, a gray box means a subnet mask and a white box means a group address. When the group address indicated by 1 is 00000001 and the collision rate of the group whose subnet mask is 00000011 exceeds the threshold, the group is divided into two groups, that is, the groups indicated by 2 and 3. The subnet mask of the divided groups is 00000111, and the upper one bit of the MAC address is used to calculate the group address.

FIG. 5A is a flowchart illustrating a process of merging groups in more detail in the above-described step S360, and FIG. 5B is a diagram illustrating an example of software implementation of the process shown in FIG. 5A, and FIG. 5C is a view of S360. A conceptual diagram illustrating a process of merging groups in a step.

First, with reference to FIGS. 5A and 5B, each group information includes a group address and a subnet mask, and when the transmission rate is determined to be less than the threshold transmission rate in step S350 described above, and there is a neighboring group to integrate First, the selected group information to be merged is deleted from the group information list (S361). For example, when a group having a subnet mask and a group address of (00000111,00000101) is integrated with a neighboring group to generate a higher group, first, the selected group information (00000111,00000101) is deleted from the group information list.

Thereafter, the selection group is integrated with the neighboring group to generate a subnet mask of the newly created upper group (S362). The subnet mask generated in step S362 is generated by setting the most significant bit set to 1 of the bits of the subnet mask of the selection group to 0. For example, in the above-described example, the most significant bit set to 1 of the subnet mask 00000111 of the selection group is set to 0 to generate 00000011 as the subnet mask of the upper group to be generated by integrating.

After the subnet mask of the upper group is set, the AP searches for a neighbor group address to be merged into the upper group together with the current group (S363), and deletes the found group information from the group information list (S364). The neighbor group that can be integrated together should be a group that can use the subnet mask of the integration group newly created in step S362 described above. Accordingly, groups in which the bit corresponding to the bit set to 1 in the newly created subnet mask have the same group address as the selection group are searched. In the above example, since the subnet mask of the upper group to be newly integrated and generated is 00000011, 00000001 is searched for the lower 2 bits of the group address equal to 01 which is the lower 2 bits of the address 00000101 of the current group.

Thereafter, the AP AND-operates the group address of the selected group and the subnet mask of the upper group to generate a group address of the upper group (S365), and groups the group information of the upper group including the generated upper group address and the subnet mask. The information is registered in the information list (S366). In the above-described example, an AND operation is performed on the subnet mask (00000011) of the upper group to be generated by integrating with the group address (00000101) of the selected group to generate (00000001) as the group address of the upper group.

As described above, a series of processes for merging groups by supernetting is conceptually illustrated in FIG. 5C. In FIG. 5C, in order to merge a group having a group address of 00000001 and a subnet mask of 00000111 into a higher group, the group of 2 and 3 is combined to become a group of 1. The subnet mask of the combined group is 00000011.

6 is a block diagram illustrating a functional configuration of an access point apparatus for performing the above-described WLAN communication method according to a preferred embodiment of the present invention.

Referring to FIG. 6, the access point apparatus of the present invention includes a communication unit 610, a collision rate calculator 620, a rate calculator 630, a group information generator 650, a group information list storage 660, and the like. The controller 640 includes a control unit 640, and the group information generator 650 includes a group divider 652 and a group merger 654.

Since the function of the access point apparatus has been described above with reference to FIGS. 2 to 5C, here, only a brief description with reference to FIG. 6, the communication unit 610 transmits and receives packet data with communication terminals in a cell area in a wireless manner. By connecting to a wired or wireless Internet network, communication terminals enable communication with other communication means.

The collision rate calculator 620 performs step S322 described above, and the rate calculator 630 performs step S326 described above.

The group divider 652 performs the above-described step S340, and the group combiner 654 performs the above-described step S360.

The group information list storage unit 660 stores group information generated by the group information generation unit 650.

The controller 640 performs all functions other than the functions performed by the above-described elements among the functions described with reference to FIGS. 2 to 5C. That is, the controller 640 selects a group from the group list, generates a beacon message including the group address and the subnet mask of the selected group, and transmits the generated beacon message through the communication unit 610.

In addition, the controller 640 determines whether to split the selection group by comparing the collision rate with the threshold collision rate, and determines whether to integrate the selection group by comparing the transmission rate with the threshold transmission rate.

The invention can also be embodied as computer readable code on a computer readable recording medium. Computer-readable recording media include all types of recording devices that store data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion.

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation.

In particular, it should be noted that the above-described calculation method of collision rate and transmission rate, transmission time allocated to a group, critical collision rate, and critical transmission rate may be set in various ways in consideration of a communication environment.

The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

1 is a diagram illustrating a general configuration of a wireless local area network.

2 is a diagram showing the structure of a beacon frame periodically transmitted from the AP to the user terminal according to an embodiment of the present invention.

3A and 3B are flowcharts illustrating an adaptive grouping process performed in the preferred embodiment of the present invention.

4A is a flowchart illustrating a process of dividing a group in more detail, and FIG. 4B is a diagram illustrating an example of a software implementation of the process illustrated in FIG. 4A, and FIG. 4C conceptually illustrates a process of dividing a group. It is a figure explaining.

5A is a flowchart illustrating a process of merging groups in more detail, and FIG. 5B is a diagram illustrating an example of a software implementation of the process illustrated in FIG. 5A, and FIG. 5C conceptually illustrates a process of merging groups. It is a figure explaining.

6 is a block diagram illustrating a functional configuration of an access point apparatus for performing the above-described WLAN communication method according to a preferred embodiment of the present invention.

Claims (12)

(a) the AP transmitting a beacon message including a group address and a subnet mask of a group (selection group) selected by the AP to communication terminals in its cell area; (b) transmitting the data to the AP when the communication terminals receiving the beacon message AND AND their MAC address and the subnet mask and compare with the group address; (c) the AP dividing the selection group into subgroups according to a collision rate or a transmission rate of data received from the communication terminals, or generating a higher group by combining the selection group and a neighbor group; And (d) performing the above-mentioned steps (a) to (c) with respect to the lower groups or the upper groups. The method of claim 1, wherein step (c) And dividing the group corresponding to the group address into subgroups when the collision rate of the data transmitted by the communication terminals is equal to or greater than a threshold collision rate. The method of claim 2, wherein step (c) (c1) generating a subnet mask of the subgroups; (c2) generating group addresses of the subgroups; And and (c3) registering, in the subgroups, group information including a subnet mask and a group address in a group information list. The method of claim 3, wherein step (c1) And generating a subnet mask of the lower groups by setting an upper bit of the most significant bit set to 1 among the bits of the subnet mask of the group indicated by the group address to 1. The method of claim 3, wherein The subgroups are composed of a first subgroup and a second subgroup, In the step (c2), the group address of the first subgroup is generated by setting a bit corresponding to the most significant bit of the subnet mask generated in the step (c1) to one among the bits of the divided group address. WLAN communication method. The method of claim 5, wherein the second subgroup uses a group address of the selection group. The method of claim 1, wherein step (c) And generating a higher group by integrating the selection group and the neighbor group when the transmission rate of the data transmitted by the communication terminals is less than a threshold transmission rate. 8. The method of claim 7, wherein step (c) (c4) generating a subnet mask of the higher group; (c5) searching for the neighboring group to be integrated with the selection group to form the higher group; And (c6) generating a group address of the higher group. The method of claim 8, wherein step (c4) And generating a subnet mask of the upper group by setting the most significant bit set to 1 among the bits of the subnet mask of the selected group to 0. The method of claim 8, wherein step (c5) And searching for groups having bits having the same group address as a selection group whose bits corresponding to bits set to 1 in the subnet mask of the upper group generated in step (c4). The method of claim 8, wherein step (c6) And generating a group address of the upper group by performing an AND operation on the selection group address and the subnet mask of the upper group generated in the step (c4). An access point apparatus according to any one of claims 1 to 11, which performs the WLAN communication method.

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