JP2003244161A - Connection equipment for wireless lan system, connection method for wireless lan, program for wireless lan, and recording medium for wireless lan system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the hidden terminal problem and reduce to the utmost consumption power of an access point (AP; connection equipment) for a wireless LAN system performing wireless communication with a terminal, by relating the AP of interest to the terminal located in a cell (communication area) determined by the transmission power. <P>SOLUTION: By grasping the loads of a plurality of APs by mutually transmitting/ receiving the loads through a wired LAN 2, and controlling transmission power to a terminal based on the load conditions of the APA and its neighboring AP, the APA is controlled to increase the transmission power output, etc., when the neighboring AP is in a high load condition and the APA is in a low load condition, so as to assist the communication performed by the neighboring AP. As such, by sharing the loads in the overall wireless LAN system, it becomes possible to solve the hidden terminal problem virtually. Moreover, it becomes possible to suppress the transmission power of each AP by controlling the transmission power of the neighboring AP in such a way as increasing the power only when assisting the communication of the APA, while generally maintaining the transmission power in a normal condition. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a terminal (computer) in a communication area (cell) defined by transmission power.
The wireless LAN system connection device (AP: Access Point) that performs wireless communication with this terminal by associating with the terminal.
t), a wireless LAN connection method, a wireless LAN system program, and a wireless LAN system recording medium.

[0002]

2. Description of the Related Art Along with the computerization of companies and universities, LAN
Many (Local Area Networks) are built. However, when the layout of the room is changed, it may be necessary to rewire, or it may be difficult to newly wire in an old precious building. In order to deal with these problems, a wireless LAN in which a part or most of the wiring is replaced with a wireless device has been attracting attention and has been standardized.

Distributed access control of a MAC (Media Access Control) layer for controlling how data is transmitted on a medium (in a wireless LAN, not a cable, a space) using a LAN. As a method, there is a CSMA (Carrier Sense Multiple Access) method. In this CSMA method, each device on the LAN detects the presence / absence of a carrier on the channel and transmits a frame when there is no carrier. In this method, a carrier cannot be detected due to a transmission delay or the like, and a frame collision occurs when the frame is transmitted. For wired LAN, CSM in IEEE 802.3 with a frame collision detection function during transmission and a frame transmission interruption function added to the CSMA method.
A / CD (Carrier Sense Multiple Access with Collis
ion detection: carrier detection multiple access / collision detection) is standardized. However, in a wireless LAN, it is difficult to detect frame collision during transmission, so
CSMA / CA with a collision avoidance function added to the CSMA method
(Carrier Sense Multiple Access with Collision Avoi
dance: carrier sense multiple access / collision avoidance) has been proposed and studied. According to this CSMA / CA method,
The terminal transmits a frame to an AP (Access Point: connection device) in the vicinity, and transmits the frame again if there is no response from the AP even after a certain period of time.

However, when a large number of terminals concentrate only in a specific area and the terminals carry out a large amount of data communication, the channel load increases, and the total request amount of the terminals tightens the channel capacity, so that communication within the channel occurs. This leads to a decrease in efficiency and communication quality. Therefore, in general, AP takes measures such as limiting the number of connected terminals or lowering the communication rate with each terminal when the channel load becomes high. As a method of limiting the number of such connected terminals, a new association request for a terminal is rejected, or a terminal that has already been associated is forcibly disconnected. Although this method can reduce the channel load of each AP, it does not necessarily lead to improvement or maintenance of the availability of the entire network. A terminal that has been refused or forcibly disconnected from the AP that has become a high-load AP can use another channel (A
P) and search for the maximum RSSI (Receive Signal Streng
th Indicator: Received radio wave intensity) is selected, but RSSI may be insufficient due to a long distance from the AP during this search, radio wave propagation conditions, etc., and communication with sufficient quality may not be performed. This situation is likely to occur especially when the terminal is located near the AP. Such a situation can be explained using FIG. That is, FIG.
As shown in FIG. 3, the terminals α and β are located in the communication area of AP _A , and the terminal α is located away from AP _A.
Consider the case where is close to AP _A. In such a case, if the communication with AP _A is disconnected, terminal α
Since it is also located in the cell of P _E , it is possible to perform wireless communication with AP _E by searching for AP _E. However, since the terminal β is not located in the cell of any other AP, it cannot perform subsequent communication. Such a terminal β is a so-called “hidden terminal” that cannot receive mutual transmission signals, such as when the distance between wireless terminals is longer than the range of radio waves or when there is an obstacle that blocks radio waves between them. It can be said that they are in substantially the same state. Therefore, CS
In the MA / CA method, when a problem of “hidden terminal” occurs, a terminal that cannot communicate transmits the same frame many times, resulting in a vicious cycle in which the channel load further increases.

As a measure against this "hidden terminal" problem, C
SMA / CA system with RTS / CTS (Request To Send / C)
A method of adding a communication right control mechanism based on the lear to send method is generally known. This RTS / CTS method is defined by the IEEE 802.11 standard, and is a signal requesting transmission permission (RTS) and a signal responding to transmission permission (CTS).
Are used in combination. That is, the terminal adds RTS to check whether or not transmission is permitted, and the transmission permission CT is sent from the AP.
The transmission can be performed when the S frame is received. In this method, the transmission-permitted CTS frame transmitted by the AP is also transmitted to a terminal other than the terminal that transmitted the RTS, so it is known that another terminal is communicating with the AP at that time, and CSMA / It is possible to solve the problem of transmitting the same RTS frame many times as in the CA method.

[0006]

[Problems to be Solved by the Invention] However, RTS
Although the / CTS method can solve the problem of a vicious circle caused by repeating the above-described retransmission, it does not solve the direct problem of "hidden terminals" that transmission / reception cannot be performed. Therefore, the availability of the entire network remains limited.

Further, instead of paying attention to the transmission method as described above, paying attention to the transmission power of the AP, as shown in FIG. 14, the transmission power of the AP is increased to increase the cell size and the terminal β. It is possible to solve the direct problem of the "hidden terminal" by locating it in the cell of the AP. That is, by increasing the cell of each AP as shown in FIG. 14, the terminal β is next _AP D, to get into the cells of the AP _E, even unable to communicate with AP _A, AP _D or A
It is possible to communicate with P _E. However, increasing the cell size increases the transmission power.
Is not preferable from the viewpoint of low power consumption. Moreover, if the transmission power is increased too much, radio wave interference between APs may occur.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and an object thereof is to solve the problem of "hidden terminal" while suppressing the power consumption of the AP as much as possible.

[0009]

In order to achieve the above object, the invention according to claim 1 relates to a wireless LAN for performing wireless communication with a terminal within a communication area determined by transmission power. In the system connection device, a load state determination unit that determines the load state of the connection device of its own, a load state notification unit that notifies the connection state of the load state determined by the load state determination unit, and the connection of the vicinity Load state receiving means for receiving the load state of the connection device in the vicinity notified from the device, its own load state determined by the load state determining means, and the load state in the vicinity received by the load state receiving means. And a transmission power control means for controlling the transmission power based on the above.

According to a second aspect of the present invention, the control of the transmission power by the transmission power control means is performed when the own load state is lower than a certain value and when the neighboring load state is higher than the certain value. The wireless LAN system connection device according to claim 1, wherein the transmission power value is increased.

According to a third aspect of the present invention, the transmission power control by the transmission power control means controls the transmission power value regardless of the neighboring load states when the own load state is higher than a certain value. The connection device for a wireless LAN system according to claim 1, wherein the connection device is maintained or lowered.

According to a fourth aspect of the present invention, there is provided the wireless LAN system connecting device according to the first aspect, further, within the communication area of its own, based on its own load condition judged by the load condition judging means. A new association with an unassociated terminal in, and an association determining means for determining subsequent association with a terminal that is already associated, and an association executing means for executing the association determined by the association determining means, Wireless LA characterized by having
It is a connection device for N system.

The invention according to claim 5 is characterized in that, in the case of disconnecting the association with the already associated terminal, the association determining means preferentially disconnects from the terminal having a smaller received power from the terminal. The wireless LAN according to claim 4.
It is a connection device for the system.

According to a sixth aspect of the present invention, there is provided a wireless LAN connection method using a connection device for a wireless LAN system, which performs wireless communication with a terminal within a communication area defined by transmission power. A load state determination process for determining the load state of its own connection device, a load state notification process for notifying the connection state of the load state determined by the load state determination process to a connection device in the vicinity, and the connection state notified from the connection device in the vicinity Based on the load state reception processing for receiving the load state of the connection device in the vicinity, the own load state determined by the load state determination processing, and the load state in the vicinity received by the load state reception means, the transmission power And a transmission power control process for controlling the wireless LAN connection method.

According to a seventh aspect of the present invention, the control of the transmission power by the transmission power control process is performed when the load state of the self is lower than a certain value and the neighboring load state is higher than the certain value. The wireless LAN connection method according to claim 6, wherein the transmission power value is increased.

According to an eighth aspect of the present invention, in the transmission power control by the transmission power control processing, when the self load state is higher than a constant value, the transmission power value is set regardless of the neighboring load states. The wireless LAN connection method according to claim 6, characterized in that the wireless LAN connection is maintained or lowered.

The invention according to claim 9 is the wireless LAN connection method according to claim 6, further comprising association in the communication area of the self based on the self load status determined by the load status determination processing. Executes an association determination process that determines a new association with a terminal that has not been associated and a subsequent association with a terminal that is already associated, and an association execution process that executes the association determined by the association determination process. And a wireless LAN connection method.

According to a tenth aspect of the present invention, in the case of disconnecting the association with the already associated terminal, the association determination processing preferentially disconnects from the terminal having smaller received power from the terminal. The wireless L according to claim 9, characterized in that
This is an AN connection method.

According to an eleventh aspect of the present invention, there is provided a wireless LAN system program used in a wireless LAN system connection device for performing wireless communication with a terminal within a communication area defined by transmission power. , A load state determination unit that determines the load state of its own connection device, a load state notification unit that notifies the connection state in the vicinity of the load state determined by the load state determination unit, and a notification from the connection device in the vicinity Based on the load status receiving means for receiving the load status of the connection device in the vicinity, the own load status determined by the load status determining means, and the load status in the vicinity received by the load status receiving means, the transmission And a transmission power control means for controlling electric power, and a wireless LAN connection device functioning as a wireless LAN connection device. It is a Temu for the program.

Here, the "program" in the present invention is a program consisting of an ordered sequence of instructions suitable for processing by the wireless LAN system connection device (computer), such as a computer HDD, CD-RW, etc. Installed on, CD-ROM, DVD, F
D, those recorded on various recording media such as a computer HDD are also included.

According to a twelfth aspect of the present invention, the control of the transmission power by the transmission power control means is performed when the own load state is lower than a certain value and when the neighboring load state is higher than the certain value. The wireless LAN system program according to claim 11, wherein the transmission power value is increased.

According to a thirteenth aspect of the present invention, the transmission power control by the transmission power control means controls the transmission power value irrespective of the neighboring load states when the own load state is higher than a certain value. The program for a wireless LAN system according to claim 11, wherein the program is maintained or lowered.

An invention according to claim 14 is the program for a wireless LAN system according to claim 11, further comprising:
An association determination for determining a new association with a terminal that is not associated and a subsequent association with a terminal that is already associated, within the communication area of its own, based on its own load status determined by the load status determining means. It is a program for a wireless LAN system, characterized in that the means and the association executing means for executing the association determined by the association determining means are caused to function in the wireless LAN system connection device.

The invention according to claim 15 is characterized in that, in the case of disconnecting an association with a terminal that has already been associated, the association determining means disconnects preferentially from a terminal having a smaller received power from the terminal. The wireless L according to claim 14.
It is a program for AN system.

The invention according to claim 16 is for a wireless LAN system readable by a connection device for a wireless LAN system, characterized in that the program for the wireless LAN system according to at least one of claims 11 to 15 is recorded. It is a recording medium.

Here, the "recording medium" in the present invention may be any one that can be used for reading a program for causing each unit to function in a connection device (computer) for a wireless LAN system, and is a physical medium of information. It does not depend on the physical recording method such as how to record using the characteristics. For example, FD, CD-ROM (R, R
W), DVD-ROM (RAM, R, RW), MO, M
D, magnetic tape, etc. are applicable.

[0027]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the overall configuration of a wireless LAN system 1 according to this embodiment. As shown in Figure 1,
The wireless LAN system 1 includes an AP _A as a connection device capable of communicating via the wired LAN 2 and a nearby AP (AP
_B ) and a computer terminal (here, terminal α) capable of communicating with each AP using a wireless LAN. Since the APs have the same configuration, the configuration of AP _A will be described below. Further, in the present embodiment, a case will be described where AP _A performs wireless communication with terminal α.

The AP _A includes a main control unit (CPU) 10 for performing the AP _A whole control, AP _A, including the main control unit
It has a program storage unit 11 in which a program (p) necessary for the whole operation is stored. This program (p)
Is a program for causing AP _A to execute a function (process) described later.

The AP _{A also} includes an antenna 12 for wireless communication with the terminal α, a switch 13 connected to the antenna 12, and a transmitter 14 for transmitting a radio wave by switching the switch 13 and a radio wave. The receiver 15 is provided for receiving. Furthermore, AP _A is
And a transmission / reception control unit 17 that controls the operation of the reception unit 15. Further, AP _A includes a transmission power control unit 16 that controls the transmission power of the transmission unit 14, and the operation of the transmission power control unit 16 is controlled by the main control unit 10.
Furthermore, AP _A includes a received power measuring unit 18 that measures the power of the radio wave received by the receiving unit 15. Also, AP _A
The main control unit 10 includes a load measuring unit 19 that measures the load of the self AP _{A in} order to determine three load states described below. Further, the AP _A includes an external interface 20 for connecting the main control unit 10, the external setting terminal 3 and the wired LAN 2.

Further, AP _A has a transmission power value table 2
1, received power value table 22, load threshold table 23,
And the adjacent AP definition table 24 is constructed.

Of these, in the transmission power value table 21, as shown in FIG. 2, the power value is set for each transmission power level, and the transmission power control unit 16 changes the transmission power of the transmission unit 14. This is the table used.

As shown in FIG. 3, the received power value table 22 has an RSSI for each terminal MAC address of each terminal.
Is a table for managing the
Manage the power value (latest value) measured in. The received power measuring unit 18 measures the power value for each terminal associated with its own AP _A , and adds an entry for this terminal each time communication with the terminal is performed, if there is no entry for this terminal. If there is, update the value.

As shown in FIG. 4, the load threshold table 23 is a table for managing a load threshold (%) that determines the channel load state of the self AP _A.

The neighbor AP definition table 24 is shown in FIG.
As shown in FIG. 5, it is a table for managing the MAC addresses of APs near the own AP _A. Near AP managed by this near AP definition table 24, and one or more AP installed in the vicinity of the self-AP _A, self AP _A
AP having a cell that overlaps the cell of This neighborhood AP
Is set in consideration of the AP placement topology and the radio wave propagation situation.

The values managed in the transmission power value table 21, the load threshold value table 23, and the adjacent AP definition table 24 can be input using the setting terminal 2, and the tables 21 and 23 are used. , 24, input data before starting AP _A.

Next, the characteristic part of this embodiment will be described in more detail. The characteristic functions of the present embodiment are roughly classified into (1) determination of the load state of the self AP _A , (2) change of terminal association based on the determined load information, (3).
Self AP _A based on the load state of the self-AP _A and vicinity AP
Since the transmission power is changed, the characteristics will be described separately below.

(1) Judgment of load state of self AP _A The load measuring unit 19 individually adopts the channel busy rate, the number of terminals associated with the self AP _A , the CPU usage rate of AP _A , or the like. The load value of self AP _A is measured by adopting in combination. Further, the main control unit 10 determines the load state of the self AP _A based on the load measurement value measured by the load measuring unit 19. This determination method is based on the load measurement value measured by the load measurement unit 19 shown in FIG.
6 is selected from the four load thresholds (L _HtoL , L _LtoH , L _{Et oH} , L _HtoE ) by referring to the load threshold table 23 shown in FIG.
It is determined which of the three load states (low load, high load, and extremely high load) is based on the state transition concept of the load state. The load threshold value shown in FIG. 4 is an example, and the present invention is not limited to this.

The load threshold value shown in FIG. 4 must be set so as to make a hysteresis transition with respect to the load state. The reason for setting in this way is that if the load state of the AP _A changes frequently at short intervals, the following problems occur. That is, on the AP _A side, the association processing and the transmission power control described later by the main control unit 10 are frequently performed,
Causing a process increase in AP _A, the terminal α-side, by performing the switching of AP frequently, the overhead of the communication increases, a problem that the channel load increases.

Further, every time the load state of the own AP _A is changed by the main control unit 10, all the neighboring APs are notified of the above-mentioned determined load state via the external interface 20 and the wired LAN 2. . On the contrary, the neighborhood A
Every time the load state of P changes
The load status notification of the neighboring AP notified via 2 is received.

(2) Change of terminal association based on the determined load state The main control unit 10 determines the association with the terminal based on the determined load state of the self AP _A as shown in FIG. To do. For example, when the self AP _A has a low load, the request for new association (transmission permission request) from the terminal is permitted and the association with the already associated terminal is maintained. Also, when the self AP _A has a high load, the request for new association from the terminal is rejected, but the association with the already associated terminal is maintained. Further, when the self AP _A has an extremely high load, it rejects the request for new association from the terminal and forcibly disconnects the association with the already associated terminal.

Regarding the forced disconnection of the association, the reception power value table 22 shown in FIG. 3 is referred to, and the terminals having lower reception power are preferentially one by one at a predetermined time interval (t.
_trans ) and control to disconnect. As a result, the position of the terminal is disconnected in the order closer to the periphery of the cell (the order farther from AP _A ), so that the possibility of appearance of a hidden terminal, which is likely to occur near AP _A , is reduced while the association is performed. The cutting can be done. However, the disconnection order may be changed depending on the radio wave propagation situation or the movement of the terminal.

Regarding the predetermined time interval (t _trans ), that is, the disconnection interval of the association, when the load state of the self AP _A changes due to the disconnection of the terminal, the new steady load value is reduced. Set so that the time until transition is secured.

(3) Change of transmission power of self AP _A based on load states of self AP _A and neighboring AP The transmission power control unit 16 changes the load state of self AP _A or neighboring AP each time the load state of FIG. In accordance with the transmission power level instruction (Boost level / normal level) from the main control unit 10 shown in FIG. 2, based on the power value (Boost level value / normal level value) managed in the transmission power table 21 shown in FIG. The transmission power value (mW) is changed. That is, the transmission power control unit 16 determines whether the normal level or the Boost level (normal level power <Boost level power), as shown in FIG. 8, based on the self load state and the received nearby load state. Control is performed to change the transmission power of self-AP _A. Here, the difference from FIG. 7 is that in FIG.
_In contrast to changing the association with the terminal based only on the load state of _A , in FIG. 8, the transmission power level of self AP _A is controlled based on the load states of both self AP _A and neighboring APs. For example, as shown in FIG. 8, when the self AP _A has an extremely high load, even if the neighboring AP has an extremely high load, the AP _A has the transmission power regardless of the load state of the neighboring AP. The level will be kept at the normal level. On the other hand, when the nearby AP has an extremely high load and self A
When P _A has a low load, the load is distributed as a whole in the wireless LAN system 1 including the self AP _A and the neighboring APs.
P _A raises the transmission power level to Boost level and the neighboring AP
Assist.

The Boost level is set so that the radio waves reach the hidden terminal located in the cell of the neighboring AP with sufficient intensity, but the radio wave interference between the APs due to the increase of the transmission power is taken into consideration to set the same frequency. It is necessary to set the transmission power so that the radio waves in the band do not interfere with each other.

Next, the operation of the wireless LAN system 1 according to this embodiment will be described. In addition, here, each AP
From the case of the low load state as shown in FIG.
As shown in (b), a case will be described in which AP _A is in an extremely high load state (or high load state), but neighboring APs are still in a low load state. FIG. 9A shows AP _A and neighboring APs (AP _B , AP _C , AP _D , AP _E , AP _F , A.
In the wireless LAN system 1 including P _G ), AP _A
It shows the case where the terminal α, the terminal β, and the terminal γ exist in the cell. The solid arrow between AP _A and terminal β indicates the already associated state (synchronized state). That is, at this point, the AP _A is not associated with the terminal α and the terminal γ.

In the state shown in FIG. 8 (a), when the channel load of AP _A increases as a result of the terminal β performing a large amount of data communication and the like, the terminals α and γ become substantially hidden terminals.
In this case, the load measurement unit 19 of the AP _A uses the self A
Measuring the load values of P _A. Further, the main control unit 10 uses the load measurement value measured by the load measurement unit 19 to determine the self A
Determining the load state of the P _A. Here, it is determined that the high load state has been reached.

Next, the main control unit 10 determines the association with the terminal β, as shown in FIG. 7, based on the above-mentioned determined load state of the own AP _A. Based on this determination, the main control unit 10 executes the association. Here, because of the high load state, the main control unit 10 rejects the request for new association from the terminals α and γ, but maintains the association with the already associated terminal β.

On the other hand, since the load state of the self AP _A has changed from the low load state to the high load state, the main control unit 10
Via the external interface 20 and the wired LAN 2,
Notify all neighboring APs of the load status of self AP _A. As a result, the neighboring AP receives the notification from AP _A.

Next, in each of the neighboring APs, each one shown in FIG.
Instructions from the main control unit 10 (Boost level / normal level)
2) according to each transmission power table 2 shown in FIG.
Power value stored in 1 (Boost level value / Normal level
The transmission power value (mW) is changed based on
Here, each neighboring AP is in a low load state, and the neighboring AP _B
AP as a nearby AP seen from_AIs under high load
Therefore, at each nearby AP, increase the transmission power and boost level.
Change to. As shown in FIG. 9B, Bo
As a result of changing to the ost level, the cells of each neighboring AP are large
It shows the state that has become. As a result, the terminal α
_ANew connection destination A
By searching for P, AP_EOr AP_DAssociated with
It can be performed. Also, the terminal γ is also the AP_AWhen
Even if it is not possible to associate,
By searching, AP_CCan be associated with
Wear.

As described above, according to this embodiment,
For example, terminals α and γ as hidden terminals communicate with neighboring APs.
You can do so to solve the problem of hidden terminals
You can Moreover, the neighboring APs usually have a transmission power level.
To normal level, AP _AWhen assisting communication
Only the transmission power of each AP is increased to boost level.
You can hold back.

The mapping of the association process according to the load state of FIG. 7 and the mapping of the transmission power according to the load state of FIG. 8 can be customized according to the operation policy. For example, as shown in FIG. 10, as a load state, the load is "extremely low load state", which is lower than the low load state.
Is added (at the same time, the corresponding load threshold is added and the mapping of the association process is also changed), and S is set as the output level.
It is also possible to set an ave level, a normal level, and a Boost level. Moreover, by focusing only on the load state of the self-AP _A, at the time of self-AP _A is very high load, as shown in FIG. 11, it is also possible to set a lower than normal level "Save level". As described above, the mapping of the association processing according to the load state and the customization of the mapping of the transmission output level according to the load state enable fine load distribution control settings according to the operation policy. However, it is necessary to set the “Save level” within a range in which the communication quality is kept good in consideration of the decrease in the signal-to-noise ratio due to the decrease in power.

By subdividing the load state and the transmission output as described above, the operation of the wireless LAN system 1'as described below becomes possible.

Here, from the case where each AP is in the low load state as shown in FIG. 12A, the AP _A is in the extremely high load state as shown in FIG. 12B, but the neighboring APs are The case where the low load state remains will be described. 12
( _A ) shows a terminal α, a terminal β, a terminal β in a cell of AP _A in a wireless LAN system 1 ′ including AP _A and a neighboring AP.
The case where the terminal γ exists is shown. The solid arrow between AP _A and terminal β indicates the already associated state (synchronized state). That is, at this point, AP
_A is not associated with the terminal α and the terminal γ.

In the state shown in FIG. 12A, a large number of terminals β are present.
As a result of the data communication of AP, _AChannel load
As shown in FIG._AIs the terminal
Since the new association of α and γ is rejected, the terminals α and γ are
It becomes a qualitative hidden terminal state. Moreover, it's shown in Figure 10.
Sea urchin AP_AIs related to terminal β already associated
Cut the attachment. However, as shown in FIG.
P_ALowers the transmission power to the Save level and closes the AP
Raises the transmission power to Boost level. Thus wireless L
By performing load distribution as the entire AN system 1 '
Then, as shown in FIG._DOr A
P_ECan communicate with the terminal β_FAP_GCommunicate with
Enabled, terminal γ is AP_B, AP_COr AP_DCommunicate with
It will be possible.

As described above, by subdividing the transmission power to the Save level, an extremely high load state in which the association with the terminal β that the self AP _A has already associated with must be cut off. Even if self AP _A
It is possible to protect

Further, in the above embodiment, when the load on the neighboring AP is high, the antenna 12 of the AP _A is made to have directivity, and the transmission output is controlled to increase only in the direction of the neighboring AP. Good. As a result, the load can be distributed with low power consumption, and the radio wave interference with the neighboring AP can be suppressed when the output is increased. In order to realize this combined system, azimuth information is added to each neighboring AP in the neighboring AP definition table, and transmission power control for each directional antenna may be performed.

With respect to the invention according to the above embodiment,
Further, by adding the function of changing the communication rate with each terminal according to the load of the own AP _A , it is not necessary to modify or change the association method in the above embodiment.

Further, the operation of storing the program (p) in the program storage unit 11 in the above embodiment is
It is also possible to use a recording medium such as a CD-ROM in which (p) is recorded.

[0060]

As described above, according to the present invention,
A plurality of APs transmit and receive their own load states to each other, and control the transmission power based on the load state of the own AP and the load state of the neighboring APs. In the case of a load state, control such as increasing the transmission output can be performed to assist the communication of the nearby AP. In this way, by substantially distributing the load in the wireless LAN system, it is possible to solve the problem of "hidden terminals". Moreover, the transmission power of each AP can be suppressed as much as possible by controlling the transmission power such that the neighboring AP normally sets the transmission power level to the normal level and raises it only when assisting the communication of AP _A. .

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a wireless LAN system 1 according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of a transmission power value table 21 of the present invention.

FIG. 3 is a conceptual diagram of a received power value table 22 of the present invention.

FIG. 4 is a conceptual diagram of a load threshold table 23 of the present invention.

FIG. 5 is a conceptual diagram of a neighboring AP definition table 24 of the present invention.

FIG. 6 is a conceptual diagram showing a state transition of a load state of an AP.

FIG. 7 is a conceptual diagram showing a process of associating with a terminal according to a load state of a self AP according to the embodiment.

FIG. 8 is a conceptual diagram showing transmission power levels of a self AP according to load states of the self AP and a neighboring AP according to the embodiment.

FIG. 9 shows AP _A from the case where each AP is in a low load state (a).
Became extremely high load (or high load), but in the vicinity A
FIG. 5 is a diagram showing the cell size (range of communication area) in the case (b) where P is still in a low load state.

FIG. 10 is a conceptual diagram showing a process of associating with a terminal according to a load state of a self AP according to another embodiment.

FIG. 11 is a conceptual diagram showing transmission power levels of a self AP according to load states of a self AP and a neighboring AP according to another embodiment.

FIG. 12 shows a case where each AP is in a low load state (a)
_The figure which showed the cell size (range of a communication area) of the case (A) which became the extremely high load state, but the vicinity AP is still in the low load state.

FIG. 13 is a diagram showing a cell size (a communication area range) of each AP in a conventional wireless LAN system.

FIG. 14 is a diagram showing a cell size (a communication area range) of each AP in a conventional wireless LAN system.

[Explanation of symbols]

1 Wireless LAN system 2 Wired LAN 3 setting terminal 10 Main control unit 11 Program storage section 12 antennas 13 switch 14 Transmitter 15 Receiver 16 Transmission power control unit 17 Transmission / reception control unit 18 Received power measurement unit 19 Load measurement section 20 External interface 21 Transmission power value table 22 Received power value table 23 Load threshold table 24 Neighborhood AP definition table (p) Program (program for wireless LAN system)

Claims (16)

[Claims] 1. A wireless LAN system connection device that wirelessly communicates with a terminal within a communication area defined by transmission power, the load state determination method for determining the load state of a self-connection device. Means, a load status notifying means for notifying a connection device in the vicinity of the load status determined by the load status determination means, and a load status reception for receiving the load status of the connection device in the vicinity notified from the connection device in the vicinity Means, and a transmission power control means for controlling the transmission power based on its own load status determined by the load status determination means, and a nearby load status received by the load status reception means. A connection device for a characteristic wireless LAN system. 2. The control of the transmission power by the transmission power control means is performed when its own load state is lower than a certain value, and when a nearby load state is higher than the certain value,
The connection device for a wireless LAN system according to claim 1, wherein the transmission power value is increased. 3. The control of the transmission power by the transmission power control means, when the load state of the self is higher than a constant value,
The connection device for a wireless LAN system according to claim 1, wherein the transmission power value is maintained or lowered regardless of the load state in the vicinity. 4. The wireless LAN system connection device according to claim 1, further comprising: a terminal that is not associated in its own communication area based on its own load status determined by the load status determination means. An association determining unit that determines a new association with the terminal and a subsequent association with the already associated terminal; and an association executing unit that executes the association determined by the association determining unit. Wireless L to
Connection device for AN system. 5. The association determination means, when disconnecting an association with an already associated terminal, preferentially disconnects from a terminal having a smaller received power from the terminal. The connection device for the wireless LAN system described. 6. A wireless LAN connection method using a connection device for a wireless LAN system, which performs wireless communication with a terminal within a communication area determined by transmission power, the load of a connection device of the wireless LAN system. A load state determination process for determining a state, a load state notification process for notifying a connection device in the vicinity of the load state determined by the load state determination process, and a load of the connection device in the vicinity notified from the connection device in the vicinity Load state reception processing for receiving a state, a self load state determined by the load state determination processing, and a transmission power control for controlling the transmission power based on a neighboring load state received by the load state receiving means. A wireless LAN connection method, comprising: 7. The control of the transmission power by the transmission power control process is performed when the self load state is lower than a constant value, and when the nearby load state is higher than the constant value,
The wireless LAN connection method according to claim 6, wherein the transmission power value is increased. 8. The control of the transmission power by the transmission power control processing is performed when the load state of the self is higher than a constant value.
7. The wireless LAN connection method according to claim 6, wherein the transmission power value is maintained or lowered regardless of the load condition in the vicinity. 9. The wireless LAN connection method according to claim 6, further comprising: a terminal that is not associated with a terminal within its own communication area based on its own load status determined by the load status determination processing. A new association and an association determination process for determining subsequent association with the already associated terminal; and an association execution process for executing the association determined by the association determination process. Wireless LAN connection method. 10. The association determination process, when disconnecting an association with an already associated terminal, preferentially disconnects from a terminal having a smaller received power from the terminal. The wireless LAN connection method described in. 11. A wireless LAN system program used in a wireless LAN system connection device that wirelessly communicates with a terminal within a communication area defined by transmission power, the wireless LAN system program comprising: A load state determination unit that determines a load state, a load state notification unit that notifies the connection device in the vicinity of the load state determined by the load state determination unit, and the connection device in the vicinity notified from the connection device in the vicinity Load state receiving means for receiving a load state, its own load state determined by the load state determining means, and a transmission power for controlling the transmission power based on a nearby load state received by the load state receiving means. A program for a wireless LAN system, characterized in that the controller and the wireless LAN connecting device are caused to function. 12. The transmission power control by the transmission power control means is performed when the load condition of the self is lower than a constant value and when the load condition in the vicinity is higher than the constant value. 12. The program for a wireless LAN system according to claim 11, wherein the program is to increase. 13. The control of the transmission power by the transmission power control means is to maintain or reduce the transmission power value regardless of the load state in the vicinity when the load state of the self is higher than a constant value. The program for a wireless LAN system according to claim 11, characterized in that. 14. The program for a wireless LAN system according to claim 11, further comprising: a terminal that is not associated with itself within its own communication area based on its own load status determined by the load status determination means. A new association, and an association determining means for determining subsequent association with a terminal that has already been associated, and an association executing means for executing the association determined by the association determining means. A program for a wireless LAN system, characterized by causing it to function. 15. The association determination means preferentially disconnects from a terminal having a smaller received power from the terminal when disconnecting an association with a terminal that has already been associated. The program for the described wireless LAN system. 16. A wireless LAN system recording medium readable by a wireless LAN system connection device, wherein the wireless LAN system program according to at least one of claims 11 to 15 is recorded.