JP2003249935A - Radio lan system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quickly and reliably set a radio channel (ch) to be used in a channel (ch) where a high communication speed, high signal quality and a stable radio link are obtained. <P>SOLUTION: In a radio LAN system which comprises an access point (AP) provided with a carrier sense function and one or a plurality of stations (STA) provided with a carrier sense function managed by the AP and performs communication by using one channel among a plurality of channels of a radio medium, the AP scans the plurality of channels, searches for a free channel or a channel with minimum power interference potential and sets a channel used by its own system in the searched channel. <P>COPYRIGHT: (C)2003,JPO

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 including an access point (AP) which is a host and one or a plurality of stations (STA) which are terminals managed by the AP.

[0002]

2. Description of the Related Art FIG. 7 shows IEEE 802.11 and 80.
It is a flowchart which shows the communication procedure of the conventional wireless LAN system of the 2.11a, b system. This IEEE80
2.11 and 802.11a, b type wireless LAN systems use an access point (A) that is a host (base station).
P) and one or a plurality of stations (STAs) that are terminals (slave units) managed by this AP and have the same ID as that of the AP, and a plurality of wireless channels (ch) of a wireless medium. ) Is used to communicate.

First, the user turns on the power of the AP (step S11), and sets an ID (ESSID) in the turned-on AP as necessary (step S12). In addition, in these steps S11 and S12, the power is turned off.
If there are STAs that have been turned on and need to be turned on, the user turns on the powers of these STAs, and sets these STAs that have been turned on to the same ID as the AP as necessary. With this ID setting, it is possible to distinguish between a device that constitutes the own system and a device that constitutes another wireless LAN system or the like. Regarding the ID setting in step 12, the ID preset in the AP or STA
In some cases, it may be optional, such as when there is no need to change.

Next, the user sets a channel used by this system (step S101). The procedure of this channel setting will be described below. When the user sets the channel used by this system to the AP, the AP sets the above-mentioned c
On h, the synchronization establishment signal (Beacon signal) is continuously transmitted at regular intervals (for example, every 80 [ms]). Same as AP above I
Each STA to which D is set scans a plurality of channels of the wireless medium and receives a synchronization establishment signal transmitted from the AP, so that the channel to which the synchronization establishment signal is transmitted (the own system is The channel to be used) is detected, and the detected channel is set as the channel used by the STA itself.

After the ch is set in this way, the wireless link procedure of step S17 is performed between the AP and each STA, the wireless link is established in step S18, and data communication and the like is performed in step S19.

IEEE 802.11 and 802.11
The a and b system APs and STAs have a carrier sense function, and during system operation such as data communication after a wireless link has been established, the device that transmits the data must have a wireless medium before transmission. C used by own system
The congestion of h is monitored (carrier sense), it is determined whether or not there is a collision with a transmission signal from another device, and if ch is vacant, transmission is performed.

[0007]

However, in the above conventional technique, the radio waves of other systems (including other wireless LAN systems having different IDs) that use the same frequency band or the interfering waves from the microwave oven and the like are mixed. Also, when waiting for ch to become available due to the above carrier sense, a communication failure such as a decrease in communication speed or disconnection of a wireless link occurs, or a voice is delayed due to a transmission delay of data such as a moving image. There may be interruptions such as interruptions and video stoppages.

Channels to be used to avoid these obstacles
However, general users who do not have a spectrum analyzer or measurement antenna for grasping the frequency of the interference wave must search for a channel that is not affected by the interference wave by cut-and-try. There wasn't.

Further, even if the user sets channels for avoiding obstacles, the interference wave changes depending on the time zone or time, so that the previous setting is not always the best channel setting, and successive channel settings are made. It may be forced to change.

The present invention has been made in order to solve such a conventional problem, and a channel to be used is a channel which can obtain a high communication speed (throughput) and high signal quality and a stable radio link. An object of the present invention is to provide a wireless LAN system that can be set quickly and reliably.

[0011]

A wireless LAN system of the present invention comprises an access point having a carrier sense function and one or a plurality of stations having the carrier sense function managed by the access point. In a wireless LAN system that communicates with one of a plurality of channels of a wireless medium, the access point scans the plurality of channels to search for a free channel or a channel of the lowest power interference wave, which is used by the own system. The channel to be set is set to the above-mentioned searched channel.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 In Embodiment 1 of the present invention described below, when an access point (AP) which is a host (master device) is powered on,
The wireless channel (ch) used by the own system is the AP
It has a function to set by itself.

IEEE 802.11 and 802.11
The a and b type devices have a carrier sense function and measure the received electric field strength, display the measured electric field strength on a display, etc., and re-establish the wireless link when the strength falls below the limit value. It is possible to establish. By using such a carrier sense function, a plurality of channels of the user wireless medium are scanned to search for an empty channel or a channel with the lowest power interference wave, and the channel to be used is automatically determined without the need for the user to manually set the channel. Can be set.

The wireless LAN system according to the first embodiment includes an access point (AP) which is a host (master device) and a terminal (slave device) managed by the AP, as in the conventional case. It is configured by one or a plurality of stations (STAs) having the same ID as the AP. In addition, the system according to the first embodiment is a conventional wireless L
Similar to the AN system, one of the multiple channels of the wireless medium
Use one to communicate.

FIG. 1 shows a wireless LAN according to the first embodiment of the present invention.
It is a flowchart which shows the communication procedure of a system. Figure 1
In FIG. 7, the same steps as those in FIG. 7 or corresponding steps are denoted by the same reference numerals. The procedure of FIG. 1 is replaced with step S101 in the conventional procedure of FIG.
13-S16 is provided.

First, the user turns on the power of the AP (step S11), and sets the ID (ESSID) to the AP that has been turned on (step S12). In addition, in these steps S11 and S12, the power is turned off.
If there are STAs that have been turned on and need to be turned on, the user turns on the powers of these STAs, and sets these STAs that have been turned on to the same ID as the AP as necessary. With this ID setting, it is possible to distinguish between a device that constitutes the own system and a device that constitutes another wireless LAN system or the like. Regarding the ID setting in step 12, the ID preset in the AP or STA
In some cases, it may be optional, such as when there is no need to change.

The powered-on AP scans a plurality of channels of the wireless medium (step S13) and determines whether or not there is an empty channel (step S14). If there is no empty channel, the channel with the lowest power interference wave is selected (step S15).

Then, the AP uses its own empty channel or the above-mentioned channel of the lowest power interference wave c
It is set as h (step S16).

After the channel is automatically set by the AP,
The wireless link procedure of step S17 is performed between the AP and each STA, a wireless link is established in step S18, and data communication and the like are performed in step S19.

The setting of ch in step S16 is performed in the following procedure. First, AP is the above-mentioned empty c
h or the channel of the lowest power interference wave is set as the channel used by the AP itself, and the synchronization establishment signal (Be
The acon signal) is continuously transmitted at regular intervals (for example, every 80 [ms]).

Each STA to which the same ID as that of the AP is set scans a plurality of channels of the wireless medium and receives a synchronization establishment signal transmitted from the AP, thereby transmitting the synchronization establishment signal. Incoming channel (channel used by own system) is detected, and the detected channel is the ST
Set as a channel used by A itself.

As described above, according to the first embodiment, the power-on AP scans the ch to find an empty ch or a ch of the lowest power interference wave, and the c used by the own system is used.
By automatically setting h to the channel searched for above, the user does not have to search for an empty channel, and the channel to be used can be swiftly and reliably selected to a channel that provides high communication speed (throughput) and high signal quality and a stable wireless link. Can be set to.

Second Embodiment A second embodiment of the present invention described below is the same as the above-mentioned first embodiment except that another system using the same frequency band (different from the first embodiment) is used during system operation after establishing a wireless link. A communication failure such as congestion of a channel due to radio waves or interference waves of other wireless LAN systems (including IDs) is generated in the channel used by the own system, and the communication speed decreases,
When the user recognizes the above communication failure and performs an instruction to rescan the AP when the wireless link becomes unstable, the AP rescans the channel and changes the channel. Is.

The wireless LAN system according to the second embodiment is also composed of an AP having the same ID and one or more STAs, as in the above-described first embodiment, and has a plurality of channels of a wireless medium. Use one of the two to communicate.

FIG. 2 shows a wireless LAN according to the second embodiment of the present invention.
It is a flowchart which shows the communication procedure of a system. Figure 2
In FIG. 1, the same steps as those in FIG. 1 or corresponding steps are designated by the same reference numerals. The procedure of FIG. 2 is obtained by adding step S20 to the procedure of the first embodiment shown in FIG. The procedure from power-on to wireless link establishment in the second embodiment is the same as in the first embodiment.

In step S18, a wireless link is established,
When data communication etc. in step S19 is being performed,
The AP monitors whether or not the user has performed an operation for instructing rescanning of ch (step S20). And
If the rescanning operation is not performed, the procedure returns to the procedure of data communication in step S19.

The user communicates due to the congestion of the channel used by the wireless medium's own system due to the mixing of the interference wave and the interfering wave during the system operation in which the wireless link is established and the data communication is performed. Upon recognizing that a communication failure such as a decrease in speed has occurred, the AP performs the rescan operation. The AP monitors whether or not the rescan operation is performed during the operation of the system, and when the rescan operation is performed, the AP
The ch is changed (step S20).

In the above channel change, the plurality of channels are rescanned in the same procedure as when the power is turned on (step S1).
3) and it is determined whether or not there is an empty channel (step S1).
4) If there is no empty channel, the channel with the lowest power interference wave is selected (step S15).

Then, the AP resets (changes the setting) the empty channel or the channel of the lowest power interference wave as the channel newly used by the own system (step S1).
6).

After ch is changed by AP, AP
And the respective STAs, the wireless link procedure of step S17 is performed again, the wireless link is reestablished in step S18, and the process returns to the loop of steps S19 and S20.

FIG. 3 is a flowchart showing a channel changing procedure (channel changing procedure when a rescan user operation is performed) according to the second embodiment. In FIG. 3, step S
20a corresponds to the procedure of step S20 of FIG. 2, and steps S16a to S16f correspond to the procedure of step S16 of FIG. Regarding steps S16a and S16b, the procedure in step S20 of FIG.
That is, it is possible to use the procedure before rescanning ch.

When the AP detects the rescanning operation of the ch by the user (step S20a), the AP of the wireless medium c
Rescan h to secure an empty channel or select the channel with the lowest power interference wave, and
A ch change request is transmitted (step S16a).

Each STA in the system is c
h When a change request is received, a response to the request receipt (A
CK) is transmitted (step S16b).

Upon receiving the ACK from the STA, the AP sends the changed ch information to the STA (step S
16c). The changed channel information is a packet including the number of the channel to be changed (= empty channel secured by rescanning or selected lowest power interference wave channel).

Upon receiving the changed channel information, the STA transmits a response (ACK) to the AP for receiving the information (step S).
16d).

The AP transmits a ch change execution request with the ch before change to the STA in the system, and then the ch used by the AP itself is an empty ch secured by the above rescan or the selected lowest power interference wave. Change to ch
The synchronization establishment signal (Beacon signal) is continuously transmitted on the changed ch at regular intervals (for example, every 80 [ms]) (step S16e).

Upon receiving the ch change execution request, the STA changes the ch used by the STA itself to the ch designated by the change ch information, and sends a reply (ACK) to the AP on the changed ch. (Step S16f).

In such a channel changing procedure, ST
When A cannot respond to the ch change, A sends a refusal reply (NCK) to the AP in step S16b or S16d.

If even one of the STAs in the system responded with an NCK, the AP will execute step S16c.
And the channel change is stopped without performing the procedure of S16e or the procedure of step S16e. After the STA responds in step S16b or S16d,
Until the change execution request is received, normal operation continues on the channel before the change. Therefore, there is no problem even if the AP stops changing channels. By providing such a sequence, it is possible to give the degree of freedom to the procedure for changing channels.

Further, the AP is a system for all STAs in the system.
Waits for a response, and then performs the procedure of steps S16c and S16e or the procedure of step S16e. Alternatively, the STA that does not respond within the time measured by a timer is disconnected from the system (de-authent
ication), the procedure of steps S16c and S16e or the procedure of step S16e is performed on the STA that has responded with ACK. The STA that does not respond within the above time corresponds to, for example, an STA whose power is turned off after the wireless link is established.

As described above, according to the second embodiment, if the user performs a rescan operation during system operation, the AP
However, by rescanning the channel to find an empty channel or a channel with the lowest power interference wave, and changing the channel used by the own system to the channel found by the above rescan, a communication failure occurs during system operation. However, it is possible to promptly secure a high transmission rate, a high signal quality, and a stable wireless link.

Embodiment 3 In Embodiment 3 of the present invention described below, another system using the same frequency band (different I
It is determined whether or not a communication failure such as congestion of a channel due to a mixture of radio waves or other interfering waves (including other wireless LAN systems in which D is set) occurs in the channel used by the wireless medium own system. Is monitored, and when the above communication failure is detected, the AP is provided with a function of automatically changing the channel without user's operation.

The wireless LAN system according to the third embodiment is also composed of the AP and the one or more STAs to which the same ID is set, similarly to the above-mentioned second embodiment, and the plurality of channels of the wireless medium are used. Use one of the two to communicate.

FIG. 4 shows a wireless LAN according to the third embodiment of the present invention.
It is a flowchart which shows the communication procedure of a system. Figure 4
In FIG. 2, the same steps as those in FIG. 2 or corresponding steps are designated by the same reference numerals. The procedure of FIG. 4 is obtained by adding step S21 to the procedure of the second embodiment shown in FIG. The procedure from the power-on to the establishment of the wireless link in the second embodiment and the procedure for changing the channel when the user performs a rescan operation on the AP in step S20 are the same as those in the second embodiment.

In step S18, a wireless link is established,
When data communication etc. in step S19 is being performed,
The AP monitors whether or not the user has performed an operation of instructing rescanning of the ch (step S20), and also monitors whether or not a communication failure has occurred in the ch used by its own system. (Step S21). If there is no rescan operation and no communication failure is detected, the process returns to the step S19 for data communication.

During the system operation in which the wireless link is established and the data communication is performed, the AP monitors the congestion degree of the channel used by the own system of the wireless medium by using the function such as carrier sense. Based on this congestion, it is determined whether or not a communication failure has occurred, and if a communication failure has occurred, ch change is performed (step S21).

To detect the degree of congestion of the wireless medium, for example, a predetermined threshold value is set in advance for signal quality and signal strength, the signal quality and signal strength are detected, and those signal quality and signal strength are set in advance. It is done by comparing with a threshold that has been set. Then, for example, if the detected signal quality or signal strength is equal to or lower than the threshold value, it is determined that a communication failure has occurred, and the ch is changed.

In changing the channel due to the detection of the communication failure,
The AP rescans the plurality of channels in the same procedure as the channel change by the user operation in the second embodiment (step S13), determines whether there is an empty channel (step S14), and determines the empty channel. If there is not, c of the lowest power interference wave
h is selected (step S15), and the empty channel or the channel of the lowest power interference wave is reset (changed) as the channel newly used by the system (step S1).
6).

After the channel is automatically changed by AP,
The wireless link procedure of step S17 is performed again between the AP and each STA, the wireless link is reestablished in step S18, and the process returns to the loop of steps S19-S21.

FIG. 5 shows a channel change procedure (AP) of the third embodiment.
Is a flowchart showing a procedure for changing a channel when a communication failure is detected. In FIG. 5, step S21a corresponds to the procedure of step S21 of FIG.
a-S16f corresponds to the procedure in step S16 of FIG. Note that steps S16a and S16b may be the procedure in step S21 of FIG. 4, that is, the procedure before rescanning the ch.

When the AP detects congestion of the channel used by the wireless medium own system (step S21a), c
Rescan h to secure an empty channel or select the channel with the lowest power interference wave, and
A ch change request is transmitted (step S16a). The procedure of steps S16a to S16f in FIG. 5 is the same as the procedure when the rescan operation is performed by the user (the procedure of steps S16a to S16f in FIG. 3).

As described above, according to the third embodiment, the AP
When a communication failure is detected, the channel can be changed to avoid a channel that is voluntarily congested, and a high transmission rate and a high signal can be promptly achieved without the need for constant user monitoring and manual operation. Quality and stable wireless links can be secured.

Fourth Embodiment In the fourth embodiment of the present invention described below, in the third embodiment, the AP and STA monitor whether or not a communication failure has occurred in system operation. ST
When A detects the above-mentioned communication failure, it has a function of automatically changing the channel without user's operation.

The wireless LAN system of the fourth embodiment is also composed of the AP and the one or more STAs to which the same ID is set, as in the third embodiment.
Communicate using one of multiple channels of a wireless medium.

The communication procedure of the fourth embodiment is the same as the communication procedure of the third embodiment (see FIG. 4). Also, in the fourth embodiment, the procedure from power-on to wireless link establishment, the procedure for changing the channel when the user rescans the AP in step S20, and the AP detects a communication failure in step S21. The procedure for changing the channel at this time is the same as that in the third embodiment.

In step S18, a wireless link is established,
When data communication etc. in step S19 is being performed,
The STA monitors whether there is a communication failure in the channel used by its own system (step S2).
1). If no communication failure is detected, step S
Returning to the procedure of 19 data communication and the like.

The STA uses a function such as carrier sense during the system operation in which a wireless link is established and data communication or the like is performed, and the channel of the channel used by its own system of the wireless medium is used. The degree of congestion is monitored, and it is determined based on the degree of congestion whether a communication failure has occurred. If a communication failure has occurred, the AP is requested to change the channel (step S21).

However, unlike the fourth embodiment, S
The system cannot operate unless the TA operates under the control of the AP, and therefore the STA itself cannot request the system to change the channel. Therefore, the STA requests the AP to change the channel, and the AP that has received the request changes the channel.

AP that received a request for channel change from the STA
Rescans the plurality of channels in the same procedure as the channel change of the third embodiment (step S13), and the empty c
It is determined whether or not there is h (step S14), and an empty channel
If there is not, the channel of the lowest power interference wave is selected (step S15), and the empty channel or the c of the lowest power interference wave is selected.
The h is reset (changed) as the channel newly used by the own system (step S16).

FIG. 6 shows a wireless LAN according to the fourth embodiment of the present invention.
It is a flowchart which shows the channel change procedure (channel change procedure when STA detects a communication failure) of a system. 6, steps S21b to S21d correspond to the procedure of step S21 in FIG. 4, and steps S16a to S16.
f corresponds to the procedure in step S16 of FIG. Note that steps S16a and S16b may be the procedure in step S21 of FIG. 4, that is, the procedure before rescanning the ch.

When any of the STAs in the system detects the congestion of the channel used by its own system of the wireless medium (step S21b), it notifies the AP in the system of the channel.
A change request is transmitted (step S21c).

Upon receiving the ch change request, the AP transmits a request acceptance reply (ACK) to the STA (step S21d).

When the AP receives the ch change request, the AP rescans the ch to reserve an empty ch or selects the ch of the lowest power interference wave, and the ST in the system is started.
A channel change request is transmitted to A (step S16).
a). The procedure of steps S16a to S16f in FIG. 6 is the same as the procedure when the AP detects a communication failure (the procedure of steps S16a to S16f in FIG. 4).

As described above, according to the fourth embodiment, even when the STA detects a communication failure not only by the AP during system operation, but also by changing the channel, it is possible to further ensure the congestion of the ch. It can be avoided promptly, and high transmission rate and high signal quality and stable radio link can be secured.

The above-described first to fourth embodiments have been described on the premise that they are incorporated into the currently mainstream "IEEE802.11b, but any wireless LAN system using carrier sense (and its application software) can be used. These systems (and their application software) include, for example, the following (1) to (8): (1) Wireless LAN PCMCIA card station and its application software (2) ) Wireless LAN USB connection station and its application software (3) Wireless LAN PCI card connection station and its application software (4) Wireless LW access point and its application software (5) Wireless LAN IP telephone (6) Wireless LAN IP telephone access point and its application software (7) Inter-building wireless LAN station and its application software (8) Television equipped with IEEE 802.11 and 11a, b type wireless interface Equipment such as audio and audiovisual equipment

[0066]

As described above, according to the present invention, there is an effect that a channel to be used can be quickly and surely set to a channel which can obtain a high communication speed and high signal quality and a stable wireless link.

[Brief description of drawings]

FIG. 1 is a flowchart showing a communication procedure of a wireless LAN system according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a communication procedure of the wireless LAN system according to the second embodiment of the present invention.

FIG. 3 is a flowchart showing a channel changing procedure of the wireless LAN system according to the second embodiment of the present invention.

FIG. 4 is a flowchart showing a communication procedure of the wireless LAN system according to the second embodiment of the present invention.

FIG. 5 is a flowchart showing a channel changing procedure of the wireless LAN system according to the third embodiment of the present invention.

FIG. 6 is a flowchart showing a channel changing procedure of the wireless LAN system according to the fourth embodiment of the present invention.

FIG. 7 is a flowchart showing a communication procedure of a conventional wireless LAN system.

[Explanation of symbols]

AP access point (host, base unit) STA station (terminal, handset)

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Claims (5)

[Claims] 1. An access point having a carrier sense function, and one or a plurality of stations having the carrier sense function managed by the access point, wherein the access point is one of a plurality of channels of a wireless medium. In the wireless LAN system that communicates with, the access point (a) scans the plurality of channels for a free channel or a channel with the lowest power interference wave, and (b) searches for a channel used by the own system. Wireless L characterized by being set to a channel
AN system. 2. The wireless LAN system according to claim 1, wherein the access point performs the steps (a) and (b) when the power of the access point is turned on. . 3. The access point, when a rescan instruction is issued during operation of the system, performs the steps (a) and (b) to reconfigure the channel used by the own system. Claim 1 characterized by the above-mentioned.
Alternatively, the wireless LAN system described in 2. 4. The access point monitors whether or not a communication failure has occurred in a channel used by the system itself during the operation of the system, and if the communication failure is detected, the access point (a) and The wireless LAN system according to any one of claims 1 to 3, wherein the channel used by the own system is reset by performing the procedure of (b). 5. The station monitors whether or not a communication failure has occurred in a channel used by the system during operation of the system, and when the communication failure is detected, the station is notified of a channel failure. A request for resetting, and upon receiving the request, the access point performs the steps (a) and (b) to reset the channel used by its own system. The wireless LAN system according to any one of 1 to 4.