JP2004015287A - Emergency access point, wireless communication system, control method of emergency access point, fault recovery method of wireless communication system, and control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless communication system or the like capable of avoiding the throughput of the entire system from being reduced in an ordinary state and ensuring communication equal to that in the ordinary state even in an emergency even when a duplicate configuration is adopted for an access point in providing a fail safe device such as the access point to a wireless LAN system. <P>SOLUTION: The emergency access point performs only reception until receiving a fault signal from a fault detection means and acts like an access point function after receiving the fault signal. The emergency access point is placed in the very vicinity of an ordinary access point or shares an antenna in common with the ordinary access point. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication system having an access point and a client terminal wirelessly connected to the access point, and more particularly to a wireless communication system having a failure relief function.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a wireless LAN system (wireless Local-Area-Network system) that configures a network between a bridge device called an access point connected to a wired LAN and a large number of wireless terminals has been proposed.
[0003]
FIG. 6 is a block diagram of a conventional wireless LAN system.
The wireless LAN system shown in FIG. 1 includes an access point 100 serving as a bridge with a wired LAN, client terminals 201 to 204 which are wireless terminals communicating with the access point 100, and a LAN cable L constituting a wired LAN. ing.
[0004]
The access point 100 transmits beacon (bacon) information ba at regular intervals. Upon receiving the beacon information ba from the access point 100 at the time of power-on or roaming, the client terminal 201 transmits a management frame, starts negotiation processing with the access point 100, and then starts communication with the access point 100. I do.
[0005]
Next, a configuration having a fail-safe mechanism at the time of failure of an access point will be described with reference to the block configuration diagram of FIG.
[0006]
The wireless LAN system shown in FIG. 7 has a configuration in which an access point 101 is added to the wireless LAN system shown in FIG. As shown in the figure, since the access points 100 and 101 have overlapping communicable areas, they transmit beacon information ba and bb at regular intervals using different channels (frequency bands).
[0007]
Upon receiving the beacon information ba from the access point 100 at the time of power-on or roaming, the client terminal 201 transmits a management frame, starts negotiation processing with the access point 100, and then starts communication with the access point 100. I do. The client terminal 202 also starts communication with the access point 101 after starting negotiation processing for the access point 101 in the same procedure.
[0008]
Here, if the access point 100 breaks down for some reason, or if the wired LAN cannot communicate at the end of the LAN cable L to which the access point 100 is connected, the client terminal 201 directly communicates with the access point 100. Since communication or communication with the access point 100 via the wired LAN cannot be continued, the client terminal 201 starts a search process for another access point 101.
[0009]
Here, the access point 101 can easily communicate with the client terminal 201 because the communicable range overlaps with the access point 100, and the client terminal 201 can immediately establish a link with the access point 101 and continue communication.
[0010]
[Problems to be solved by the invention]
However, the fail-safe mechanism in the conventional wireless LAN system has the following problems.
(1) In the above configuration, the range in which the access point 100 can communicate and the range in which the access point 101 can communicate are different due to the difference between the distance between the access point 100 and the access point 101 and the frequency band used. When the point 100 fails, there is a problem that a client that the access point 101 cannot perform sufficient proxy processing occurs.
(2) When the access points 100 and 101 have a duplex configuration, beacons and other communications are frequently transmitted from the access points 100 and 101, radio wave interference increases in a wide frequency band, and the entire LAN system However, there is a problem that the throughput is reduced.
[0011]
The present invention has been made in view of the above-mentioned conventional problems, and in providing a fail-safe mechanism such as an access point in a wireless LAN system, it is possible to avoid a decrease in the throughput of the entire system in a normal state even when the access point has a dual configuration. It is another object of the present invention to provide a wireless communication system or the like that can ensure communication equivalent to that in normal times even in an emergency.
[0012]
[Means for Solving the Problems]
To achieve the above object, the emergency access point of the present invention does not operate as an access point until receiving an abnormal signal from a client terminal connected to an external access point, and receives an abnormal signal. After that, it operates as an access point.
[0013]
In the wireless communication system of the present invention, a first access point connected to a wired communication network, a plurality of client terminals wirelessly connected to the first access point, the first access point or the wired communication network A wireless communication system including an emergency second access point that operates when an abnormality occurs, wherein an abnormality detection unit that detects an abnormality in the first access point or the wired communication network and outputs an abnormality detection signal The emergency second access point does not operate as an access point until an abnormality detection signal is received from the abnormality detection unit, and operates as an access point after receiving the abnormality detection signal. It is characterized by the following.
[0014]
In the emergency access point control method of the present invention, the operation as an access point is not performed until an abnormal signal is received from a client terminal connected to an external access point. It is characterized by operating.
[0015]
In the failure remedy method for a wireless communication system of the present invention, a first access point connected to a wired communication network, a plurality of client terminals wirelessly connected to the first access point, the first access point or A method for remedying a failure in a wireless communication system comprising: an emergency second access point that operates when an abnormality occurs in the wired communication network, wherein the abnormality is detected by detecting an abnormality in the first access point or the wired communication network. An abnormality detection unit that outputs a detection signal is provided, and the emergency second access point does not operate as an access point until an abnormality detection signal is received from the abnormality detection unit, and the abnormality detection signal is output. And operates as an access point after receiving the.
[0016]
The control program of the present invention executes the emergency second access point control method that operates when the first access point fails or when the wired communication network to which the first access point is connected is abnormal. The control program does not operate as an access point until an abnormal signal is received from a client terminal connected to the first access point, and operates as an access point after receiving the abnormal signal. It is characterized by having.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0018]
[First embodiment]
<Configuration of wireless communication system>
FIG. 1 is a conceptual diagram showing a configuration of a wireless communication system (wireless LAN system) according to the first embodiment of the present invention.
[0019]
In the figure, Pa is an access point serving as a bridge with the wired LAN, and 11 to 14 are client terminals that wirelessly communicate with the access point Pa. L1 is a LAN cable constituting a wired LAN connected to the access point Pa, and R1 is a router to which the access point Pa is connected via the LAN cable L1.
[0020]
10a is an abnormality detection device that detects an abnormality of the wired LAN to which the access point Pa is connected and transmits an abnormality detection signal. 11a to 14a detect an abnormality of the access point Pa at the client terminals 11 to 14 and perform an abnormality. This is an abnormality detection device that transmits a detection signal. Pb is an emergency access point that performs only reception until an abnormality detection signal output from the abnormality detection device 10a or the abnormality detection devices 11a to 14a is received, and operates as an access point after receiving the abnormality detection signal. Has functions.
[0021]
L2 is a LAN cable forming a wired LAN connected to the emergency access point Pb, and R2 is a router to which the emergency access point Pb is connected via the LAN cable L2.
[0022]
The emergency access point Pb is located very close to the normal access point Pa, and is located at a position where all the client terminals wirelessly connected to the access point Pa can be wirelessly connected at the same level as the emergency access point Pb. Here, 31 is a range where the access point Pa can wirelessly communicate, and 32 is a range where the emergency access point Pb can wirelessly communicate.
[0023]
<Troubleshooting procedure when the normal access point fails>
2A, 2B, and 2C are flowcharts showing a procedure for relieving a failure of the normal access point Pa. FIG. 2A is a procedure on the client terminal side, and FIG. FIG. 4C shows the procedure on the side of the normal access point.
[0024]
First, for example, the procedure (FIG. 2A) on the client terminal 11 side will be described. When the client terminal 11 receives the beacon information ba from the access point Pa at the time of power-on or roaming (step S10), the management is performed. After transmitting the frame and starting the negotiation processing for the access point Pa (step S12), the communication with the access point Pa is started.
[0025]
Here, if the client terminal 11 cannot intercept the beacon information ba for a certain period of time (step S14) even though the communication medium is open (step S13), the abnormality detection device 11a performs a test via the client terminal 11. The frame is transmitted to the access point Pa (step S15). On the other hand, if no response signal is returned from the access point Pa (step S16), the abnormality detection device 11a sends an abnormality detection signal to the emergency access point Pb via the client terminal 11 (step S17).
[0026]
Thereafter, when the beacon information bb is received from the emergency access point Pb (step S18), negotiation processing is started for the emergency access point Pb (step S19), and then communication with the emergency access point Pb is started.
[0027]
Next, the procedure (FIG. 2B) on the emergency access point Pb side will be described. When the emergency access point Pb performs only reception (step S20), the emergency access point Pb transmits an abnormality detection signal from the client terminal 11 side. After receiving (Step S21), it is confirmed that communication with the access point Pa is not possible (Step S22, Step S23), and operation as an access point is started (Step S24).
[0028]
Further, the procedure on the access point Pa side (FIG. 2C) will be described. When the access point Pa receives the beacon information bb of the emergency access point Pb while operating as an access point (step S30) ( In step S31), a mode for performing only reception immediately is set (step S32).
[0029]
<Troubleshooting procedure when the wired LAN is disconnected>
3A, 3B, and 3C are flowcharts showing a procedure for relieving a failure in the wired LAN to which the normal access point Pa is connected. FIG. FIG. 3B shows the procedure on the emergency access point side, and FIG. 3C shows the procedure on the normal access point side.
[0030]
First, for example, the procedure on the client terminal 11 side (FIG. 3A) will be described. When the client terminal 11 receives the beacon information ba from the access point Pa at the time of power-on or roaming (step S41), After transmitting the management frame and starting the negotiation process for the access point Pa (step S42), the communication with the access point Pa is started.
[0031]
Here, upon confirming that the access point Pa is disconnected from the wired LAN to which the access point Pa is connected, the abnormality detection device 10a broadcasts an abnormality detection signal to each of the client terminals 11 to 14 and the emergency access point Pb. Send (see steps S61 and S62 in FIG. 3 (c) described later). Each of the client terminals 11 to 14 receiving this abnormality detection signal (step S43) stops communication with another terminal connected via the wired LAN via the access point Pa (step S44).
[0032]
Thereafter, when the beacon information bb is received from the emergency access point Pb (step S45), negotiation processing is started for the emergency access point Pb (step S46), and then communication with the emergency access point Pb is started.
[0033]
Next, the procedure on the emergency access point Pb side (FIG. 3B) will be described. In the emergency access point Pb, when only reception is performed (step S50), an abnormality detection signal from the abnormality detection device 10a is transmitted. After the reception (step S51), a test frame is sent to another terminal connected by wire (step S52). Then, when a normal reception (Ack) signal is returned (step S53), a signal for switching to a mode of performing only reception is transmitted to the access point Pa (step S54), and the normal reception (Ack) is performed on the signal. ) When the signal is returned (step S55), it starts operating as an access point (step S56).
[0034]
Here, the emergency access point Pb is connected to a router R2 (or bridge) different from the access point Pa. Thus, even when the wired LAN to which the access point Pa is connected becomes unable to communicate for some reason, the possibility of communication with the wired LAN via the emergency access point Pb can be increased.
[0035]
If no response is returned even when the emergency access point Pb sends a test frame to another terminal connected by wire (step S53), it is impossible to connect to the wired LAN using either of the access points Pa and Pb. The access point Pa is used as it is, and the emergency access point Pb performs only reception.
[0036]
Also, the procedure on the access point Pa side (FIG. 3C) will be described. When the abnormality detection device 10a detects an abnormality of the wired LAN as described above while operating as an access point (step S60) ( In step S61, an abnormality detection signal is transmitted by broadcast to each of the client terminals 11 to 14 and the emergency access point Pb (step S62).
[0037]
Then, upon receiving a signal transmitted from the emergency access point Pb for switching to a mode of performing only reception (step S63), a normal reception (Ack) signal is returned in response to the signal (step S64), and reception is performed. This is the mode for performing only (step S65).
[0038]
In the present embodiment, the emergency access point Pb is located very close to the normal access point Pa in providing the fail-safe mechanism of the access point of the wireless LAN system. The communicable range of the operating access point Pb hardly changes, and communication equivalent to that in normal operation is secured even in an emergency.
[0039]
In addition, since the emergency access point Pb performs only reception during normal times, beacon information is not transmitted on a plurality of channels, and radio interference increases in a wide frequency band in the conventional wireless LAN system. The problem that the throughput of the system is reduced can be solved.
[0040]
[Second embodiment]
In the present embodiment, a configuration will be described in which the access point Pa and the emergency access point Pb used during normal times share an antenna.
[0041]
<Main Configuration of Second Embodiment>
FIG. 4 is a block diagram showing a main configuration of a wireless communication system (wireless LAN system) according to the second embodiment of the present invention.
[0042]
In the wireless LAN system of the present embodiment, in the configuration shown in FIG. 1, the access point Pa used during normal times and the emergency access point Pb share the antenna An1.
[0043]
That is, SW1 in the figure is a switch for switching between the access points Pa and Pb. Sn is a monitoring device that monitors a wireless or wired communication state. The monitoring device Sn is connected to the wireless communication transmitting / receiving unit Paa of the normal access point Pa, detects an abnormality of the access point Pa or the wired LAN, and controls the changeover switch SW1 according to the detection result. The signal SC is output.
[0044]
<Operation of Second Embodiment>
FIG. 5 is a flowchart showing the operation of the second embodiment.
[0045]
The monitoring device Sn does not transmit data even if the access point Pa does not output beacon information even if the RSSI (received detection signal) is low for a certain period of time or more, or data comes from the wired LAN (L1) to the wireless client terminal. When an abnormality occurs (step S71), the switch SW1 is switched to the emergency access point Pb (step S72).
[0046]
Further, when all data sent from the access point Pa to the wired LAN (L1) has been disconnected (step S73), the monitoring device Sn is connected from the emergency access point Pb to the wired LAN (L2). Then, a test frame is transmitted to another terminal (step S74).
[0047]
When the test frame is normally transmitted (step S75), the monitoring device Sn determines that the wired LAN (L1) to which the access point Pa is connected is abnormal (step S76), and sets the changeover switch SW1 to the emergency access point. Switch to Pb side (step S77).
[0048]
If there is no reply to the test frame to the other terminal (step S75), it is determined that a problem has occurred in the entire wired LAN (L1), (L2) (step S77), and the changeover switch SW1 is set to the access point Pa. Side (step S78).
[0049]
In the present embodiment, the access point Pa used during normal times and the emergency access point Pb are configured to share an antenna, so that the access point operating normally and the access point operating during emergency can perform wireless communication. The range can be made the same, and communication equivalent to the normal state can be secured even in an emergency.
[0050]
Further, similarly to the first embodiment, it is possible to solve the problem of the related art in which the interference of radio waves in a wide frequency band increases and the throughput of the entire wireless LAN system decreases.
[0051]
The program according to the flowchart of FIG. 2A or FIG. 3A is stored in the storage device in each of the client terminals 11 to 14, and the program according to the flowchart of FIG. 2B or FIG. The stored program is stored in the storage device in the emergency access point Pb, and the program according to the flowchart of FIG. 2C or 3C is stored in the storage device in the normal access point Pa to operate. The control method of each of the above embodiments can be realized.
[0052]
A storage medium storing program codes of software for realizing the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus reads out and executes the program code stored in the storage medium. It goes without saying that it will be completed by doing so.
[0053]
In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, or ROM is used. Can be. When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS or the like running on the computer performs the actual processing based on the instruction of the program code. It goes without saying that a case where some or all of the functions are performed and the functions of the above-described embodiments are realized by the processing is also included.
[0054]
Further, after the program code read from the storage medium is written to a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the expansion is performed based on the instruction of the next program code. It goes without saying that the CPU of the expansion board or the expansion unit performs the processing and performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.
[0055]
【The invention's effect】
As described above in detail, according to the present invention, the emergency access point does not operate as an access point until receiving an abnormal signal from the client terminal, so that radio interference in a wide frequency band during normal operation is avoided. It is possible to avoid the problems of the related art such that the throughput increases and the overall throughput of the wireless communication system decreases.
[0056]
In addition, the wireless communication range of the first access point operating at the time of normal operation and the second access point operating at the time of emergency can be made to be the same or almost the same, and can be equivalent to the normal time even in the case of emergency. Communication can be secured.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a configuration of a wireless communication system (wireless LAN system) according to a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating a procedure for repairing a failure of an access point Pa.
FIG. 3 is a flowchart illustrating a procedure for relieving a failure of a wired LAN to which a normal access point Pa is connected.
FIG. 4 is a block diagram showing a main configuration of a wireless communication system (wireless LAN system) according to a second embodiment of the present invention.
FIG. 5 is a flowchart showing the operation of the second embodiment.
FIG. 6 is a block diagram of a conventional wireless LAN system.
FIG. 7 is a block diagram of another conventional wireless LAN system.
[Explanation of symbols]
Pa Normal access point Pb Emergency access point 11 to 14 Wireless communication terminal 10a to 14a Abnormality detection device L1, L2 LAN cable R1, R2 Router An1 Antenna,
SW1 changeover switch,
Sn monitoring device

Claims (11)

An emergency access point which does not operate as an access point until an abnormal signal is received from a client terminal connected to an external access point, and operates as an access point after receiving an abnormal signal. A first access point connected to a wired communication network, a plurality of client terminals wirelessly connected to the first access point, and an emergency operating when the first access point or the wired communication network is abnormal. A wireless communication system including a second access point,
Having an abnormality detecting means for detecting an abnormality of the first access point or the wired communication network and outputting an abnormality detection signal,
The emergency second access point does not operate as an access point until an abnormality detection signal is received from the abnormality detection unit, and operates as an access point after receiving the abnormality detection signal. Wireless communication system. The wireless communication system according to claim 2, wherein the first access point and the second access point are arranged at a distance at which wireless communication is possible with the client terminal. The first access point and the second access point share the same antenna,
Switching means for switching and connecting the antenna to the first access point side or the second access point side according to a switching signal,
The wireless communication system according to claim 2, further comprising: a unit that outputs the switching signal in accordance with a detection result of the abnormality detection unit. The wireless communication system according to claim 2, wherein the first access point and the second access point are independently connected to a bridge or a router by wire. The emergency access point does not operate as an access point until an abnormal signal is received from a client terminal connected to an external access point, and operates as an access point after receiving the abnormal signal. Control method. A first access point connected to a wired communication network, a plurality of client terminals wirelessly connected to the first access point, and an emergency operating when the first access point or the wired communication network is abnormal. A failure remedy method for a wireless communication system including a second access point,
An abnormality detection unit that detects an abnormality of the first access point or the wired communication network and outputs an abnormality detection signal is provided,
The emergency second access point does not operate as an access point until an abnormality detection signal is received from the abnormality detection unit, and operates as an access point after receiving the abnormality detection signal. Rescue method for a wireless communication system. The method according to claim 7, wherein the first access point and the second access point are disposed at a distance that enables wireless communication with the client terminal. The first access point and the second access point share the same antenna, and the antenna is connected to the first access point or the second access point according to a detection result of the abnormality detection unit. 9. The method for remedying a failure in a wireless communication system according to claim 7, wherein the connection is switched to a connection. 10. The method according to claim 7, wherein the first access point and the second access point are independently connected to a bridge or a router by wire. At the time of the first access point failure, or the first access point is a control program for executing a control method of the second access point for emergency that operates when an abnormality of the wired communication network is connected,
It does not operate as an access point until an abnormal signal is received from a client terminal connected to the first access point, and has a feature of operating as an access point after receiving an abnormal signal. Control program.

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