JPH11317747A - Radio lan system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allows the radio LAN system, which is provided with plural master stations and allows the master stations to communicate information to slave stations in communicable areas by radio, to perform a roaming processing without measuring, for example, electric field intensity. SOLUTION: The master stations 1a and 1b have managing means which manages the identifies of slave stations 2 that the master stations 1a and 1b communicate with and, for example, a slave station 2 communicating with the 1st master station 1a moves into the communicable area R2 of the 2nd master station 1b, an informing means of the slave station 2 sends the identifier of the 1st master station 1a and its identifier to the 2nd master station 1b, so that a receiving means of the 2nd master station receives the identifier. Once the 2nd master station 1b has received the identifier of the different master station la from the slave station 2, an informing means sends the identifier of the slave station 2 to the different master station 1a through a line 3 and a registering means registers the identifier of the slave station 2 as an object of a communication partner managed by a managing means. When the 1st master station 1a receives the identifier of the slave station 2 from the different master station 1b, a deleting means deletes the identifier from the object of the communication partner managed by the managing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless LAN system in which a plurality of master stations are provided, and the master station communicates wirelessly with slave stations existing in a communicable area. The present invention relates to a technology for efficiently managing a slave station as a partner and a technology for efficiently performing roaming (handover).

[0002]

2. Description of the Related Art In a wireless LAN system, for example, a plurality of master stations are provided, and the master station wirelessly communicates information with slave stations existing in a communicable area. In such a system, for example, when a slave station moves from a communicable area of a certain master station to a communicable area of another master station, it is necessary for the other master station to take over communication with the slave station. Therefore, processing such as roaming is performed.

FIG. 8 shows an example of a master station, a slave station, and the like constituting the above-mentioned wireless LAN system. The roaming process will be described with reference to FIG. The figure shows two master stations 51 as devices constituting the wireless LAN system.
a, 51b and one slave station 52, and a first movement position 54 as a position to which the slave station 52 can move.
a to the third movement position 54c are shown. Hereinafter, for convenience of explanation, the two master stations 51a and 51b will be described as a first master station 51a and a second master station 51b, respectively.

[0004] The first master station 51a and the second master station 51b are connected via a line (backbone) 53 such as Ethernet, for example.
1b is also connected to another master station (not shown) via the line 53. In addition, the first master station 51a and the second master station 51b are provided with a function of performing wireless communication with the slave station 52 using, for example, signals of mutually different frequencies. Communication between the mobile station 52 and another slave station and communication between the mobile station 52 and a terminal such as a personal computer connected to the line 53 are realized. Note that, for example, a configuration in which a terminal is connected to the slave station 52 and the terminal performs communication via the slave station 52 may be used.

FIG. 1 shows a communicable area (service area) R3 of the first master station 51a and a communicable area (service area) R4 of the second master station 51b. In the slave station 52, the first mobile station 51a is located at the first movement position 54a within the communicable region R3 of the first master station 51a where sufficient high-quality information communication can be performed with the first master station 51a. Further, the above-mentioned second movement position 54b is the first movement position 54b.
The third mobile position 54c is a position in the area where the communicable area R3 of the master station 51a and the communicable area R4 of the second master station 51b overlap, and This is a position where sufficiently high-quality information communication can be performed with the second master station 51b.

In the above system, in the state shown in FIG. 8, information communication is performed by radio between the slave station 52 and the first master station 51a. If the user moves from the position 54a to the third moving position 54c via the second moving position 54b, the first master station 51a cannot perform wireless communication with the slave station 52. A roaming process is performed in which the station 51b takes over wireless communication with the slave station 52.

Here, as the roaming process, a process similar to the roaming (handover) process performed in a wireless system such as a mobile phone system is performed. For example, the slave station 52 is assigned to the master stations 51a and 51b.
The roaming process is performed by a configuration having a function of measuring the electric field strength of a wireless signal transmitted from the Internet. Specifically, for example, a threshold value of the electric field strength is set in the slave station 52, and when the electric field strength measured by the slave station 52 exceeds the threshold value, the slave station 52 that applies the electric field strength to the slave station 52 is set. Is performing wireless communication to take over communication with itself. In some cases, a configuration having a function of measuring the electric field strength on the master stations 51a and 51b side may be used.

In general, a wireless LAN system includes a plurality of slave stations 52, each of which has a master station 51a, 51b.
Is communicated with which of the plurality of master stations 51 by a router (not shown).
a and 51b are collectively managed. This router is connected, for example, to the first master station 51a and the second master station 51b via a line 53, and the router reads the destination of the signal packet transmitted via the line 53 and matches the packet. Processing such as transmission to the master stations 51a and 51b is performed.

[0009]

However, in the above-described wireless LAN system, the roaming process is performed in a configuration in which the function of measuring the electric field strength is provided in the slave station or the master station. For this reason, there is a problem that the amount of coding of components and software increases, and similarly, there is a problem that the cost of such components increases. Also, for example, in a wireless LAN system, a high-frequency band such as a 5 GHz band or a 19 GHz band is often used for wireless communication. However, such a high-frequency band has strong linearity as a propagation characteristic, and shadowing or the like occurs. Due to the characteristics, in such a case, there is a problem that the roaming start cannot be triggered by measuring the electric field intensity.

In the above-described wireless LAN system, for example, when a design change to add a new master station to the system or a design change to delete a used master station from the system is performed, a new change is made. The process of registering the identifier (address, etc.) of the master station to be added to the router and the process of deleting the identifier registered in the router for the master station to be deleted have to be performed. There was a problem that it could not be performed.

The present invention has been made to solve such a conventional problem, and a wireless LAN capable of performing a roaming process without performing a process of measuring an electric field strength by a slave station or a master station. The purpose is to provide a system. Another object of the present invention is to provide a wireless LAN system capable of easily performing a design change such as adding or deleting a master station.

[0012]

In order to achieve the above object, in a wireless LAN system according to the present invention, a plurality of master stations are provided, and the master station wirelessly communicates information with a slave station existing in a communicable area. At the time of communication, management means for managing an identifier of a slave station with which each master station is a communication partner is provided for each master station. Therefore, since each master station can manage the identifier of the slave station with which each master station communicates, the system does not have a router function for managing, for example, the identifier (address or the like) of each master station. For example, even when a design change such as adding a new master station to the system is performed, processing such as registering the identifier of the master station in the router is not always necessary. The system design can be easily changed and the degree of freedom in system design can be expanded.

Also, according to the present invention, the wireless LA
In the N system, roaming processing is performed as follows. That is, in the slave station, the notification means transmits the identifier of the master station of the communication partner and its own identifier, while in the master station,
Receiving means receives the identifier from the slave station. For example, when receiving the identifier of another master station from the slave station, the notifying means transmits the identifier of the slave station to another master station corresponding to the identifier. Also, at the master station, for example, when receiving the identifier of another master station from the slave station, the registration means registers the identifier of the slave station in the communication partner managed by the management means described above,
Further, for example, when an identifier of the slave station is received from another master station, the deletion means deletes the identifier from the communication partner managed by the management means.

In such a configuration, for example, when a slave station in communication moves from the communicable area of one master station to the communicable area of another master station, the other master station transmits the information from the slave station to the master station. Based on the reception of the identifier of the master station, the identifier of the slave station is registered in the communication partner, and the identifier of the slave station is transmitted to the one master station. On the other hand, the one master station deletes the identifier from the target of the communication partner based on receiving the identifier of the slave station from the other master station. Thus, in the present invention, for example, the roaming process can be performed without performing the process of measuring the electric field strength by the slave station or the master station,
This can reduce parts and the like for measuring the electric field strength and the cost thereof, and reliably perform roaming processing even when wireless communication is performed using a high frequency band such as a 5 GHz band. be able to.

Further, in the wireless LAN system according to the present invention, roaming processing is performed as follows as roaming processing different from the above-described roaming processing method. Note that, for example, the following roaming process may be performed together with the above-described roaming process. That is, the above-mentioned management means further manages a predetermined monitoring time set for a slave station managed as a communication partner, and the master station receives a message from a slave station managed as a communication partner. If the wireless information has not been received for the monitoring time, the deletion unit deletes the identifier of the slave station from the communication partner managed by the management unit.

In such a configuration, for example, when a communicating slave station moves from the communicable area of one master station to the communicable area of another master station, the one master station transmits radio information from the slave station. Is deleted from the target of the communication partner based on the fact that has not been received for a predetermined monitoring time. As described above, in the present invention, the roaming process can be performed without performing the process of measuring the electric field strength by, for example, the slave station or the master station, thereby realizing cost reduction and the like as described above. Can be.

Further, in the wireless LAN system according to the present invention, a monitoring time can be set for each slave station in the management means, whereby, for example, according to the moving speed, communication quality, etc. of each slave station. By setting a different monitoring time for each slave station, the efficiency of roaming processing can be improved. It is not always necessary to set a different monitoring time for each slave station. Further, any numerical value may be set as the monitoring time. For example, a monitoring time suitable for the roaming process may be set according to the usage status of the system.

As the identifiers of the master station and the slave stations described above, any identifier may be used as long as it identifies each master station or each slave station. Alternatively, an address assigned to each slave station can be used.
Further, the number of master stations provided in the wireless LAN system of the present invention is not particularly limited as long as it is plural, and the number of slave stations may be any number.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Wireless L according to a first embodiment of the present invention.
The AN system will be described with reference to the drawings. FIG. 1 shows an example of an apparatus constituting the wireless LAN system of the present embodiment.
Two master stations 1a and 1b and one slave station 2 are shown,
Further, a first movement position 4a and a second movement position 4b are shown as positions to which the slave station 2 can move. Hereinafter, for convenience of explanation, the two master stations 1a and 1b will be described as a first master station 1a and a second master station 1b, respectively.

The first master station 1a and the second master station 1b are connected via a line (backbone) 3 such as, for example, an Ethernet or the like, and these master stations 1a and 1b are connected via the line 3. It is also connected to other outside master stations. The figure also shows a communicable area (service area) R1 of the first master station 1a and a communicable area (service area) R2 of the second master station 1b. In the state of FIG. 2
Is the first master station 1 within the communicable area R1 of the first master station 1a.
a is located at the first movement position 4a where sufficient high-quality information communication can be performed with the first movement position 4a. In addition, the second
The movement position 4b is a position where sufficiently high-quality information communication can be performed with the second master station 1b within the communicable region R2 of the second master station 1b.

As described above, in the wireless LAN system of the present embodiment, a plurality of master stations 1a and 1b are provided, and the master stations 1a and 1b can wirelessly communicate information with the slave station 2 existing in the communicable area. For example, between the master station 1a, 1b and the slave station 2, the identifier of the master station 1a, 1b or the slave station 2
Information communication is performed by using a packet including an identifier of the above.

Here, the above-mentioned master station 1a, 1b and slave station 2
An example of the device configuration will be described in detail. In this example, since the configurations of the first master station 1a and the second master station 1b are substantially the same, an example of the device configuration of the master station 1 will be described. FIG. 2 shows an example of a device configuration of the master station 1 and the slave station 2 of the present embodiment. The master station 1 is connected to another master station or the like via the above-mentioned line 3.

The master station 1 shown in FIG. 1 performs a wireless communication unit 11 for performing wireless communication, a LAN communication unit 12 for performing communication via the line 3, and controls these processing units 11 and 12. A control unit 13 is provided. The wireless communication unit 11 includes, for example, a modulator and a demodulator, and performs a process of modulating information into a wireless signal and transmitting the same, and a process of demodulating information from a received wireless signal. In this example, the wireless communication unit 1
Receiving means 14 for receiving the identifier transmitted from the slave station 2 is constituted by the receiving function provided in the device 1. Further, in this example, signals of different frequencies are used for wireless communication between the first master station 1a and the second master station 1b shown in FIG.

The LAN communication unit 12 is composed of, for example, a modulator and a demodulator. The LAN communication unit 12 modulates information into a form suitable for the line 3 and transmits the modulated information through the line 3 or receives the information through the line 3. A process of demodulating information from a signal is performed. Control unit 1
Reference numeral 3 denotes, for example, a CPU, a ROM or a memory storing an identifier of the self, and the like.
By executing a predetermined control program stored in the CPU, the above-described control of the processing units 11 and 12 and various processes are performed. In this example, the control unit 13 includes a management unit 15 for managing the identifier of the slave station 2, a notification unit 16 for transmitting the identifier of the slave station 2 to another master station, and registration of the identifier of the slave station 2. A registration unit 17 for performing the deletion and a deletion unit 18 for deleting the identifier of the slave station 2 are provided.

The management means 15 has a function of managing the identifier of the slave station 2 with which the master station 1 communicates, for example.
In this example, such functional means are provided for each master station. FIG. 3 shows an example of the slave station management table 31 constituting the management means 15 of the present embodiment. In the slave station management table 31, the identifier of the slave station 2 with which the master station 1 is to communicate is indicated. It is remembered. In this example, as the identifier of the slave station 2 stored in the slave station management table 31, for example, "A"
A MAC address such as "AAAAA" is used.

The above-mentioned slave station management table 31 includes:
For example, when there is a packet transmitted to the slave station 2 via the line 3, the control unit 13 determines whether or not the slave station 2 is managed as a communication partner of the master station 1.
It is also referred to in the processing (filtering processing) determined by the above. In this case, for example, if the slave station 2 of the destination of the packet is managed as a communication partner of the master station 1, the packet is transmitted from the wireless communication unit 11, and, for example, the slave station 2 is managed as a communication partner. If not, the packet is discarded.

The notifying means 16 has a function of transmitting the identifier of the slave station 2 to another master station corresponding to the identifier based on the reception of the identifier of the other master station from the slave station 2 by the receiving means 14. In this example, the transmission process is performed by including the identifier of the slave station 2 in a roaming packet described later and transmitting the same to another master station via the line 3 by the LAN communication unit 12. Note that such transmission processing is specifically performed when, for example, the slave station 2 that has been performing wireless communication with another master station moves and enters its own communicable area. Further, in this example, similarly to the identifier of the slave station 2 described above, the MAC address is used as the identifier of the master station 1.

FIG. 4 shows the notification means 16 as described above.
Shows an example of a roaming packet P transmitted to another master station. The roaming packet P has an information identifier 3 indicating the content of information such as the type of information.
2 and the corresponding MAC address 33 of the slave station 2. In this example, the roaming packet P
UDP / IP packet is used as the roaming packet P in the configuration example of the roaming packet P shown in FIG.
Illustration of the IP header and the like is omitted. FIG. 1 shows an example of the roaming packet P transmitted from the second master station 1b to the first master station 1a.

The registration unit 17 registers the slave station 2 in the communication partner managed by the management unit 15 based on the reception of the identifier of another master station from the slave station 2 by the reception unit 14.
In this example, this registration process is performed in the slave station management table 31 by the MAC of the slave station 2.
This is performed by storing the address. Further, the control unit 13 stores the MAC address of the slave station in the slave station management table 31 by the registration unit 17 even when the identifier of the slave station or the like is received from a slave station that newly starts communication. Is performed.

The deletion means 18 is provided for the management means 15 based on the fact that the LAN communication unit 12 has received the identifier of the slave station 2 from another master station via the roaming packet P.
Has a function of deleting the identifier from the target of the communication partner managed by the slave station. In this example, this deletion processing is performed by deleting the corresponding MAC address stored in the slave station management table 31. Will be

With the above configuration, the master station 1 wirelessly communicates information with the slave station 2 existing in its own communicable area, and stores the MAC address of the slave station 2 as a communication partner in the slave station management table. 31 is performed, and
Processing such as registration and deletion of the MAC address in the slave station management table 31 and transmission of the roaming packet P to the other master station are performed in accordance with information received from the slave station 2 and other master stations.

In this example, the above-mentioned master station 1 has UD
P / IP is mounted, and a roaming protocol for performing processes such as management of the slave station management table 31 and transmission of the roaming packet P is provided as an upper layer protocol.
4 to 18 are configured by the CPU executing the control program. In the present invention, any configuration of each of the functional units 14 to 18 for executing the processing may be used. The means 14 to 18 may be configured as independent hardware circuits.

The slave station 2 shown in FIG. 2 includes a wireless communication unit 21 for performing wireless communication, and a control unit 22 for controlling the wireless communication unit 21 and the like. The wireless communication unit 21 includes, for example, a modulator and a demodulator, and performs a process of modulating information into a wireless signal and transmitting the same, and a process of demodulating information from a received wireless signal. The control unit 22 is, for example, a CPU
In this example, the CPU executes a predetermined control program stored in the ROM to control the wireless communication unit 21 and perform various processes. Done.

In the present embodiment, the control unit 22 includes a notifying unit 23 for transmitting the identifier (MAC address) of the master station 1 of the communication partner and its own identifier (MAC address) by the wireless communication unit 21. . The master station 1 of the communication partner
Is stored as an object of a communication partner in, for example, a memory of the control unit 22. For example, when wireless communication with the master station 1 is started completely new, the identifier received from the master station 1 is used. The identifier of the master station 1 is stored in the memory or the like,
Further, for example, when the communication is taken over by another master station during communication, the identifier of the other master station received from the other master station is overwritten in the memory or the like as a target of the communication partner. .

With the above configuration, the slave station 2 performs wireless information communication with the master station 1 with which communication is possible. At the time of the communication, the master station of the communication partner and its own MAC address are used as information. The transmission is performed inclusively. In the present example, the notifying unit 23 for performing the transmission process of the identifier is configured by executing the control program by the CPU, but in the present invention, what kind of configuration of the functional unit 23 for performing the process is applied For example, the functional unit 23 may be configured as an independent hardware circuit.

Next, referring to FIG. 1, the wireless LA of this embodiment will be described.
An example of a procedure of a roaming process performed by the N system will be described. For example, when the slave station 2 is in the first movement position 4a,
When information is communicated with the master station 1a, the MAC address of the slave station 2 is registered in the slave station management table 31 of the first master station 1a. When a packet addressed to 2 is received via the line 3, the packet is wirelessly transmitted by the above-described filtering process.

In the above case, for example, the slave station 2
When moving from the movement position 4a to the second movement position 4b,
The first master station 1a and the MAC address of the slave station 2 are notified to the second master station 1b by information communication between the slave station 2 and the second master station 1b. The MAC address of the slave station 2 is registered in the slave station management table 31, and the second master station 1b takes over the information communication with the slave station 2 by the above-described filtering process or the like.

In the second master station 1b, the MA of the slave station 2 is
The C address is included in the roaming packet P and transmitted via the line 3 to the first master station 1a.
In a, by analyzing the contents of the received roaming packet P, the MA of the slave station 2 which has already moved from its own communicable area R1 to the communicable area R2 of another master station 1b is analyzed.
The C address is deleted from the slave station management table 31. Thus, the roaming process is performed in the wireless LAN system of the present embodiment.

FIG. 5 shows an example of a procedure of processing performed by the master stations 1a and 1b in the above-described roaming processing. In this example, the first master station 1a and the second master station 1a
Since the procedure of the process performed by the master station 1b is substantially the same, the procedure of the process will be described collectively as the master station 1. In the master station 1, a slave station management process described below is started when information is received via a packet or the like by the wireless communication unit 11 or the LAN communication unit 12, for example (step S1).

When the slave station management process is started, the master station 1 first monitors whether or not there is a roaming packet P addressed to itself in IP packets transmitted via the line 3 (step S1). S2), roaming packet P addressed to itself
Is received, the MAC address of the slave station 2 included in the roaming packet P is stored in the slave station management table 31.
(Step S3). By this deletion process,
The master station 1 can perform the most accurate filtering process at that time.

Next, when such a deleting process is performed or when the roaming packet P addressed to itself is not received, the master station 1 performs the following based on the information received by the radio communication unit 11. A slave station that starts a completely new communication,
It is confirmed whether or not there is a slave station 2 that has moved from the communicable area of another master station to its own communicable area during communication, that is, a slave station 2 that newly starts communication with itself (step S4). ). In this case, if there is no slave station 2 that newly starts communication with the master station 1, the slave station management process is terminated (step S 9). The station 1 registers the MAC address of the slave station 2 in the slave station management table 31 (step S5).

Further, M to be registered in the slave station management table 31
If the slave station 2 corresponding to the AC address has moved from the communicable area of another master station (step S
6) The master station 1 generates a roaming packet P including the MAC address of the slave station 2 (step S7), and transmits the generated roaming packet P to another corresponding master station (step S8). When the roaming packet P is transmitted in this manner, or when the slave station corresponding to the MAC address registered in the slave station management table 31 starts communication completely new, the slave station concerned The management process ends (Step S9).

As described above, in the wireless LAN system of the present embodiment, the roaming process can be performed by a simple processing procedure even if the process of measuring the electric field strength is not performed by, for example, the master station or the slave station. The cost of such components and the like can be reduced by reducing the amount of coding of components and software for measuring the electric field strength, and the like.
Further, in the roaming process of the present example, since it is not necessary to perform the process of measuring the electric field strength, even when a high frequency band such as a 5 GHz band is used as the frequency band of the radio signal, the roaming process is performed reliably. Can be.

Further, in the wireless LAN system of this embodiment, for example, even when a slave station moves from the communicable area of one master station to the communicable area of another master station, the one master station does not Since the information transmission to the slave station is immediately stopped by the roaming packet from the other master station, it is necessary to immediately prevent unnecessary wireless signals from being transmitted to the slave station to its own communicable area. As a result, it is possible to reduce power consumption, reduce unnecessary transmission of radio waves, and the like.

Further, in the wireless LAN system of this example, since a management means for managing the identifier of the slave station with which each master station communicates is provided for each master station, for example, a new master station is added to the system. It is possible to easily make a design change such as adding to the system, and to expand the degree of freedom of the system design change.

In the first embodiment, when the master station receives the identifier of another master station from the slave station, the master station transmits the identifier of the slave station to the other master station. Although the roaming process is performed, for example, even when the master station transmits the identifier of another master station received from the slave station or the identifier of the slave station to all other master stations, the roaming process is performed in the same manner as described above. Processing can be performed. Also, for example, even when a configuration is used in which the master station transmits the identifier of the slave station received from the slave station to all other master stations, all other master stations receive the identifier from the master station. If the received identifier of the slave station is stored in its own slave station management table, the roaming process can be performed by deleting the identifier. In such a case, for example, the identifier of the master station of the communication partner need not be transmitted from the slave station.

Next, the wireless LA according to the second embodiment of the present invention
The N system will be described with reference to the drawings. Wireless LA of this example
The configuration of the N system and the configuration of the master station and slave stations constituting the system are almost the same as the configuration examples shown in FIGS. 1 and 2, for example. The description will be made with reference to the stations 1a and 1b and the slave stations 2. The roaming process performed in this embodiment is mainly performed by the management unit 15 and the deletion unit 18 of the master station 1 shown in FIG.
Only the steps 5, 18 and the roaming process will be described. In this example, the description will be made using the same reference numerals as those shown in FIGS. 1 and 2 as the reference numerals of the respective devices and the respective processing units.

The roaming process of the present embodiment described below may be used together with the roaming process of the first embodiment. In this case, for example, each of the functional units shown in the first embodiment may be used. 14 to 18 are provided in the master station 1 and the function of performing the roaming process shown in this example is managed by
The system can be configured by further providing the device 5 and the deletion unit 18. Further, the roaming process of the present embodiment may be performed separately from the roaming process shown in the first embodiment, for example. In this case, the roaming process shown in the first embodiment may be performed in the master station 1. May not be provided, as long as it has at least a function capable of executing the roaming processing of the present example. In this example, it is assumed that the configuration of the slave station 2 is the same as that of the first embodiment.

First, an example of the configuration of the management unit 15 and the deletion unit 18 of the master station 1 shown in FIG. 2 will be described. FIG. 6 shows an example of the slave station management table 41 constituting the management means 15 of the present embodiment. The slave station management table 41 includes a slave station 2 managed by the master station 1 as a communication partner. (For example, "slave station 1", "
The slave station 2 ″,...) And a time-up value (second) for the slave station 2 are stored and managed. As a method of specifying the slave station name, for example, the MAC address described above is used. Used.

Here, in this example, for example, M
With the AC address, the name of the slave station is the slave station management table 4.
1, the predetermined monitoring time for the slave station 2 is set in the slave station management table 41 by the control unit 13 or the like as an initial value of the time-up value, and the time-up value thus set is set. Are rewritten at regular time intervals by a deletion unit 18 described later, and are reduced. As described above, the management unit 15 of this example not only manages, for example, the identifier of the slave station 2 with which the master station 1 communicates, but also sets the identifier of the slave station 2 managed as the communication partner. It also manages the specified monitoring time. In addition, for example, a configuration in which the monitoring time is set for each slave station may be used in the slave station management table 41 that configures the management unit 15. In such a configuration, for example, a different monitoring time is set for each slave station. Can also be set. In addition, an arbitrary time may be set as the monitoring time according to the usage status of the system.

The deletion means 18 of this embodiment has, for example, a timer for measuring the time. As described above, the time-up value corresponding to the slave station name stored in the slave station management table 41 is updated at regular intervals. While having the function of rewriting and reducing (counting down), if the wireless communication unit 11 receives any wireless information from the slave station 2 whose time-up value is not 0, the slave station 2 It has a function of resetting the corresponding time-up value to an initial value (in this example, the above-described predetermined monitoring time). Further, the deletion unit 18 has a function of deleting the name (MAC address) of the slave station 2 whose time-up value has become 0 from the slave station management table 41. With such a function, the deletion unit 18 of the present example has a function. The management unit 15 manages the wireless information from the slave station 2 managed as a communication partner based on the fact that the wireless communication unit 11 has not received the monitoring time set for the slave station 2. The identifier of the slave station 2 (in this example, the slave station name specified by the MAC address, for example) is deleted from the communication partner.

In the master station 1 having the above-described functional means 15, 18 and the like, when information is communicated with the slave station 2, for example, the name of the slave station 2 of the communication partner is managed with the MAC address, and If the wireless information from the slave station 2 is not received during the monitoring time, the slave station 2
Is deleted from the slave station management table 41. In this example, as in the case of the above-described first embodiment, each master station 1 is provided with a function of managing the identifier of the slave station 2 to be a communication partner.
For example, the identifier of the slave station 2 which starts communication completely new is registered in the slave station management table 41, or the slave station 2 which has moved from the communicable area of another master station to its own communicable area.
It is possible to efficiently perform, for example, taking over the communication with the device.

Next, referring to FIG. 1, the wireless LA of the present embodiment will be described.
An example of a procedure of a roaming process performed by the N system will be described. For example, when the slave station 2 is in the first movement position 4a,
When information is communicated with the master station 1a, the name of the slave station 2 is set to MA in the slave station management table 41 of the first master station 1a.
In addition to being registered with the C address, a time-up value corresponding to the slave station 2 is stored and managed.

In the above case, for example, the first master station 1a
Before the time-up value of the slave station 2 stored in the slave station management table 41 becomes zero, the slave station 2 moves to the first movement position 4a.
From the second mobile station 4b to the second mobile station 4b, the second master station 1b is notified of the MAC address of the slave station 2 by information communication between the slave station 2 and the second master station 1b. The name of the slave station 2 is registered in the slave station management table 41 of the second master station 1b with the MAC address, and a predetermined monitoring time for the slave station 2 is set as an initial value of the time-up value. In this way, the second master station 1b takes over the information communication with the slave station 2 concerned.

On the other hand, the first master station 1a determines that the wireless information from the slave station 2 that has moved from its own communicable area R1 to the communicable area R2 of another master station 1b has not been received for a predetermined monitoring time. Based on this, the name of the slave station 2 is deleted from the slave station management table 41. Thus, the roaming process is performed in the wireless LAN system of the present embodiment.

FIG. 7 shows an example of a procedure of processing performed by the master stations 1a and 1b in the roaming processing described above. In this example, the first master station 1a and the second master station 1a
Since the procedure of the process performed by the master station 1b is substantially the same, the procedure of the process will be described collectively as the master station 1. In the master station 1, for example, when a slave station 2 of a communication partner exists, a slave station management process described below is performed at regular intervals (step S11).

In the slave station management process, the master station 1 first updates the time-up value corresponding to each slave station 2 registered in the slave station management table 41 (step S).
12). In the update processing of the time-up value, for example, when the slave station management processing is performed at regular intervals as in this example, the time-up value is reduced by the time. The parent station 1 searches whether or not there is a time-up value of 0 (or has become smaller than 0) by the above-mentioned update processing (step S13). The slave station name or the like corresponding to the time-up value that has become (or smaller than 0) is deleted from the slave station management table 41 (step S14).

When the deletion processing is performed as described above or when there is no time-up value which is 0 (or smaller than 0) by the above-described update processing, the master station 1
Then, the information signal from the slave station 2 is monitored to start a completely new communication with the slave station, or from the communicable area of another master station to the communicable area of the own station during communication. It is confirmed whether or not the mobile station 2 has moved (step S15). If there is such a mobile station 2 that newly starts communication with itself, the name of the mobile station 2 is determined. Is registered in the slave station management table 41 with a MAC address, for example, and a predetermined monitoring time is set as an initial value of a time-up value in association with the slave station name (step S1).
6).

When such a new registration has been made or when there is no newly registered slave station, the master station 1 monitors the radio information from the slave station 2 and , The slave station 2 that transmitted the wireless information
, The time-up value stored in the slave station management table 41 is reset to the initial value (step S17). In this way, in the master station 1, the slave station management process ends (step S18).

As described above, in the wireless LAN system of the present embodiment, the roaming process can be performed with a very simple configuration even if the process of measuring the electric field strength is not performed by, for example, the master station or the slave station. Also, since it is not always necessary to equip the master station or slave station with components or software for measuring the electric field strength, for example, the number of components constituting the master station or slave station can be reduced, and the amount of software coding can be reduced. And the efficiency of the roaming process can be improved. Further, even when a high frequency band such as a 5 GHz band is used as a frequency band of a wireless signal, the roaming process can be performed reliably.

Also, in the wireless LAN system of this embodiment, as in the case of the wireless LAN system shown in the first embodiment, the management means for managing the identifier of the slave station with which each master station is to communicate is provided. Since the master station is provided for each master station, design changes such as adding a new master station to the system can be easily performed, and the degree of freedom in system design change can be expanded. Further, in the wireless LAN system of this example, for example, the monitoring time set for each slave station is made different according to the function of each slave station, so that the efficiency of the roaming process can be improved. As the monitoring time, for example, when a slave station newly starts communication with the master station, the slave station notifies the master station of its own monitoring time, and the monitoring time notified by the master station is the child station. It is also possible to use a configuration in which settings are made for stations.

Here, in the above-described first and second embodiments, two master stations and one slave station constituting the wireless LAN system have been described as an example. There is no particular limitation on the number of master stations provided that it is plural, and there is no particular limitation on the number of slave stations.
For example, when the master station communicates with a plurality of slave stations, the roaming process is performed for each slave station by managing identifiers and the like of the plurality of slave stations.

Further, in the first and second embodiments described above, the case where the MAC address is used as the identifier of the master station or the slave station has been described, but what kind of identifier is used. Is also good. In the first and second embodiments described above, the wireless communication is performed between the master station and the slave stations, while the master station communicates with the other master station via a wired line. Although the configuration for communication has been described, for example, a configuration in which wireless communication is performed between a master station and another master station may be used.

[0064]

As described above, according to the wireless LAN system of the present invention, when a plurality of master stations are provided, and when the master station wirelessly communicates information with a slave station existing in a communicable area, Since the identifier of the slave station with which each master station communicates is managed for each master station, it is possible to easily change the design of the system. Further, in the present invention, further, when the master station receives the identifier of another master station from the slave station, the master station notifies the other master station of the identifier of the slave station,
Since the identifier of the slave station notified by the other master station is deleted from the management target, for example, efficient roaming processing can be realized without performing the electric field strength measurement processing.

Further, according to the wireless LAN system of the present invention, the master station manages the monitoring time set for the slave station, and when the monitoring information is not received from the slave station, the master station manages the monitoring time. Since the identifier of the slave station is deleted from the management target, efficient roaming processing can be realized even if, for example, the electric field strength measurement processing is not performed. Further, according to the present invention, for example, a monitoring time can be set for each slave station, and thereby, a roaming process suitable for a use condition of the system can be realized.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration example of a master station and slave stations according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a slave station management table.

FIG. 4 is a diagram illustrating an example of a roaming packet.

FIG. 5 is a diagram illustrating an example of a procedure of a slave station management process performed by a master station.

FIG. 6 is a diagram illustrating an example of a slave station management table.

FIG. 7 is a diagram illustrating an example of a procedure of a slave station management process performed by a master station.

FIG. 8 is a diagram showing a configuration of a wireless LAN system according to a conventional example.

[Explanation of symbols]

1, 1a, 1b ··· master station, 2 ··· slave station, 3 ··· line, 4a, 4b ··· moving position, R1, R2 ··· communicable area, P · · roaming packet, 11 · · · wireless communication unit , 12 LAN communication unit, 13 control unit, 1
4 receiving means, 15 managing means, 16 notifying means, 17 registering means, 18 deleting means, 21
-Wireless communication unit, 22-Control unit, 23-Notification means, 31, 41-Slave station management table,

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshifumi Suzuki 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (4)

[Claims] A wireless LAN in which a plurality of master stations are provided and the master station wirelessly communicates information with slave stations existing in a communicable area.
In the system, each of the master stations is provided with management means for managing an identifier of a slave station with which the master station is to communicate with, for each of the master stations.
AN system. 2. The wireless LAN system according to claim 1, wherein the slave station includes a notifying unit for transmitting an identifier of a master station of the communication partner and an identifier of the self station, while the master station further includes a notification from the slave station. Receiving means for receiving the identifier; notifying means for transmitting the identifier of the slave station to another master station corresponding to the identifier based on receiving the identifier of the other master station from the slave station; Registration means for registering the slave station identifier in the communication partner managed by the management means based on the reception of the master station identifier, and that the slave station identifier has been received from another master station. And a deletion unit for deleting the identifier from the communication partner managed by the management unit based on the above. 3. A wireless LA according to claim 1 or claim 2.
In the N system, the management unit further manages a predetermined monitoring time set for a slave station managed as a communication partner, and further controls the master station from a slave station managed as a communication partner. A wireless LAN system comprising: a deletion unit that deletes an identifier of the slave station from a communication partner managed by the management unit based on the fact that wireless information is not received during the monitoring time. 4. The wireless LAN system according to claim 3, wherein a monitoring time is set in said management means for each slave station.