JP5953564B2 - Access point and access point control method - Google Patents

Description

  The present invention relates to an access point and an access point control method.

  With the recent widespread use of wireless LAN environments, radio communication transmission radio waves are increasing. For example, when an access point (AP) is installed in each house in an apartment house, etc., there is a concern that interference will occur with each other, and problems such as reduced throughput due to radio wave interference and difficulty in connecting to the network will increase. . Therefore, carrier allocation is performed with respect to the frequency channel (CH: Channel) at the access point, and the channel with the lowest received signal strength with respect to the radio waves emitted by other access points is selected to improve the efficiency of channel allocation ( For example, see Patent Document 1).

JP 2009-1003006 A

  However, when the number of access points increases, there is no frequency channel spacing in the 2.4 GHz band, and therefore radio wave interference may occur even when moving to a frequency channel with low radio wave intensity. If there are many access points on the same frequency channel even if a frequency channel without interference is selected, transmission waiting by CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance) Therefore, there is a problem that the throughput is greatly reduced.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to allocate channel of access points in a wireless communication system using a frequency band in which a plurality of access points overlap frequency bands. It is to provide a technique for controlling radio waves and suppressing radio wave interference.

  In order to solve the above problem, the present invention provides an access point in a wireless communication system having a plurality of frequency channels, and whether or not other access points other than its own access point are communicating for each frequency channel. A channel scan unit that periodically executes a channel scan to be detected, and when a parent access point is not detected in the channel scan that is executed at the time of startup, the own access point is set as a parent access point, and the channel scan that is executed at the time of startup When the parent access point is detected, a parent AP child AP control unit having the own access point as a child access point, and when the own access point is a child access point, based on the channel scan result, Interference degree When the channel interference degree determination unit to determine and the own access point is a child access point, when the radio wave interference degree in the frequency channel used by the own access point is greater than the radio wave interference degree in other frequency channels, When a request to change the frequency channel is made to the parent access point, and the own access point is the parent access point, a child is based on a channel switching threshold in the frequency channel being used and a channel change request from the child access point. And a channel controller that assigns a frequency channel to the access point.

  In the invention described above, the present invention is characterized in that the frequency channels assigned to the access point by the channel controller are the frequency channels that do not overlap each other.

  Moreover, the present invention is characterized in that, in the above-described invention, the channel control unit calculates the threshold based on the number of the access points allocated to each of the frequency channels.

  Further, the present invention is characterized in that, in the above-described invention, the channel control unit calculates the threshold value based on the number of stations using each of the frequency channels.

  Further, the present invention is characterized in that, in the above-described invention, the parent access point predetermines an access point to be a next parent access point when the parent access point stops.

  Further, according to the present invention, in the above-described invention, when the access point is a child access point, the communication is performed by changing the channel used by the parent access point only during the communication between the access points. It is characterized by performing.

  The present invention is also a method for controlling an access point in a wireless communication system having a plurality of frequency channels, and a channel for detecting whether or not other access points are communicating in addition to the own access point for each frequency channel. If a parent access point is not detected in a channel scan procedure that periodically executes a scan and the channel scan that is executed at the time of startup, the parent access point is set as the parent access point, and the parent scan is executed by the channel scan that is executed at the time of startup. When the point is detected, the parent AP child AP control procedure using the own access point as the child access point, and when the own access point is the child access point, the radio wave interference degree in the frequency channel is determined based on the channel scan result. Judgment Channel interference level determination procedure, and when the own access point is a child access point, when the radio wave interference degree in the frequency channel used by the own access point is greater than the radio wave interference degree in other frequency channels, If a request to change the frequency channel is made to the parent access point, and the own access point is the parent access point, the child access based on the channel switching threshold in the frequency channel being used and the channel change request from the child access point A channel control procedure for assigning frequency channels to points.

  According to the present invention, a network in which an access point in a wireless communication system is a parent or a child is formed. The access point attempts to suppress radio wave interference by using any one of the frequency channels that do not interfere with each other according to the current degree of interference. In addition, by preventing many access points from concentrating on the same frequency channel, the number of access points that use each frequency channel is smoothed, channels that do not interfere with each other are used, and communication throughput is not reduced. Thus, the communication load can be smoothed. In addition, since the access points that use each frequency channel are distributed, the frequency channels used by stations (STAs) connected to each access point are also distributed, and the frequency channel usage efficiency is also smoothed. , A decrease in communication throughput can be suppressed.

It is a figure which shows the outline of the network structure of the parent access point and child access point in the radio | wireless communications system which concerns on one Embodiment of this invention. It is a figure which shows the functional block of the access point in the embodiment. It is a figure which shows an example of the data structure in parent AP management DB in the embodiment. It is a figure which shows an example of the data structure in SSID number DB in a parent cell in the embodiment. It is a figure which shows an example of the data structure in parent-child SSID number DB in the embodiment. It is a figure which shows an example of the data structure in STA number DB in the embodiment. It is a figure which shows an example of the data structure in the interference degree table in the embodiment. It is a figure which shows an example of the data structure in the information element in the beacon frame in the embodiment. It is a flowchart explaining the parent AP child AP setting process in the embodiment. It is a flowchart explaining the next parent AP determination process in the parent AP in the embodiment. It is a conceptual diagram of AP control which parent AP in the embodiment performs. It is a figure explaining the flowchart of a child AP channel control process in the embodiment. It is a flowchart explaining the process at the time of the parent AP stop in the child AP in the embodiment. It is a flowchart explaining the parent AP channel control process in the embodiment. It is a conceptual diagram of the AP channel switching upper limit threshold calculation pattern in the same embodiment. It is a flowchart explaining the channel switching upper limit threshold value calculation process in the same embodiment. It is a sequence diagram explaining a parent AP takeover process at the time of a parent AP stop in the embodiment. It is a sequence diagram explaining a parent AP takeover process at the time of parent AP abnormal stop in the embodiment. It is a conceptual diagram which shows the channel setting at the time of communication between AP in the embodiment. It is a flowchart explaining the channel setting control process at the time of communication between AP in the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an outline of a network configuration of a parent access point and a child access point in a wireless communication system according to an embodiment of the present invention.
The wireless communication system 1 includes a plurality of parent access points 100 (100-1, 100-2), a plurality of child APs 200 (200-1, 200-2, 200-3), and a plurality of stations (hereinafter referred to as STAs). ) 300 (300-1, 300-2,..., 300-11). Hereinafter, the access point is referred to as AP. That is, the parent access point is called a parent AP, and the child access point is called a child AP. Note that an explanation that does not require a distinction between the parent AP 100 and the child AP 200 is simply referred to as an AP.
Each of the parent AP 100 and the child AP 200 communicates with a plurality of STAs 300. A range where radio waves reach from each AP is referred to as a cell 400. In FIG. 1, the cells 400 of the parent APs 100-1 and 100-2 are shown as an example.

FIG. 2 is a diagram showing functional blocks of the access point in the present embodiment.
The AP has the same functional block configuration in the parent AP 100 and the child AP 200, and operates as either the parent AP 100 or the child AP 200 by processing at the time of AP activation or AP stop described later.
The AP includes an antenna 105, a wireless communication unit 110, a communication control unit 120, and a storage unit 160.
The antenna 105 transmits and receives radio signals to and from other APs 100 and 200 and the STA 300.
The radio communication unit 110 performs demodulation processing of radio signals received from the other APs 100 and 200 and the STA 300 and modulation processing of data transmitted to the other APs 100, 200 and STA 300 via the antenna 105.

The communication control unit 120 includes a beacon control unit 121, a timing control unit 122, a channel scan unit 123, a channel control unit 124, a parent AP child AP control unit 125, and a channel interference degree determination unit 126.
The beacon control unit 121 generates a beacon signal (hereinafter referred to as a beacon) that is periodically transmitted to APs and STAs present in the cell. Also, beacons periodically received from APs present in the cell are analyzed.
The timing control unit 122 controls timing for transmitting and receiving radio signals. Data transmission / reception timing with other communication devices including the APs 100 and 200 and the STA 300 and timing control of periodically executed processes are performed. For example, control is performed such that a beacon is transmitted every 100 msec and a channel scan is executed every 5 minutes. The time interval for executing the process can be set to an arbitrary value by an input from the user.

The channel scanning unit 123 periodically performs carrier sense for detecting whether or not other access points are communicating other than the own access point for all frequency channels. For example, when another access point is communicating, the other access point is detected by receiving a beacon or a packet.
The channel control unit 124 performs channel control of the frequency channel used by the access point in the wireless communication system 1.
The parent AP child AP control unit 125 controls the parent child network formed by the access points in the wireless communication system 1.
The channel interference level determination unit 126 determines the frequency channel interference level from the beacon received by the access point by channel scanning. For example, information such as radio wave intensity obtained from a beacon transmitted by another access point is used for the determination of the degree of interference.

The storage unit 160 stores a parent AP management DB 161, a parent cell SSID (Service Set IDentifier) number DB 162, a parent / child SSID number DB 163, an STA number DB 164, an interference degree table 165, and a channel switching upper limit threshold calculation pattern setting file 166.
The SSID is a network identification name set for the access point by the user. By setting only both access points and STAs that have the same SSID to communicate with each other, radio interference can be prevented.
The channel switching upper limit threshold calculation pattern setting file 166 stores setting information in a channel upper limit threshold calculation process which will be described later with reference to FIG. The contents to be set can be set by user input. In an example of this embodiment, whether to enable or disable is stored for each of a plurality of channel switching upper limit threshold calculation patterns.

FIG. 3 is a diagram illustrating an example of a data configuration in the parent AP management DB 161 in the present embodiment.
The parent AP management DB 161 stores data for identifying the parent AP and the next parent AP. Here, when the function of the parent AP is stopped, the next parent AP is an AP that takes over the function of the parent AP and becomes a new parent AP. The determination process of the next parent AP will be described later.
The parent AP management DB 161 stores a table including items of belonging NO, MAC address, CH, SSID, and status. In the example shown in FIG. 3, attribution NO “1”, MAC address “00: 1A: 2B: 3C: 4D: 5E: 5F”, CH “1”, SSID “SSID01”, and status “parent” are shown. . In the item “Attribution NO”, “No. 1 indicates that the AP with the MAC address corresponding to 1 is the current parent AP. In the item “status”, an arbitrary code indicating a parent, for example, “parent” is stored. On the other hand, the item “attribute NO” 2 is attribute NO. 2 indicates that the AP with the MAC address corresponding to 2 is the current next parent AP. In the item “status”, an arbitrary code indicating the next parent, for example, “next parent” is stored. The item “MAC address” indicates a 12-digit hexadecimal value unique to each AP. Items “CH” and “SSID” indicate the frequency channel used by the MAC address and the SSID name for both the parent AP and the next parent AP.

FIG. 4 is a diagram illustrating an example of a data configuration in the parent cell SSID count DB 162 according to the present embodiment.
The parent cell SSID count DB 162 includes the items “target CH”, “parent AP cell range SSID count”, “acquisition time”, “SSID average value” for each channel used by the AP. Record records that contain In this example, the target channels are 1, 6, and 11, and the record includes, for example, the target channel “1”, the number of SSIDs in the parent AP cell range “A”, and the acquisition time “YYYY / MM / DD / hh / mm / ss ”and SSID average value“ (A + B + C) / number of target channels ”are shown.

FIG. 5 is a diagram illustrating an example of a data configuration in the parent-child SSID number DB 163 in the present embodiment.
The parent / child SSID number DB 163 includes the items “target CH”, “parent AP and child AP SSID numbers”, “acquisition time”, “acquisition time”, “ Records including “SSID average value” are stored. In this example, the target channels are 1, 6, and 11, and the record includes, for example, the target channel “1”, the number of parent AP and child AP SSID “A”, and the acquisition time “YYYY / MM / DD / hh / mm / ss ”and SSID average value“ (A + B + C) / number of target channels ”are shown.

FIG. 6 is a diagram illustrating an example of a data configuration in the STA number DB 164 in the present embodiment.
The number of STAs DB 164 includes, for each unique MAC address assigned to each AP, the number of STAs belonging to the parent AP in the parent AP cell range and the total number of STAs belonging to the child APs for each unique MAC address. Records including “number of STAs”, “acquisition time”, and “average number of STAs” are stored. In this example, as the record for the MAC address “00: 1A: 2B: 3C: 4D: 5E” of the target AP, for example, the number of STAs “A”, the acquisition time “YYYY / MM / DD / hh / mm / ss”, The STA number average value “(A + B +... + X) / number of target channels” is shown.

FIG. 7 is a diagram illustrating an example of a data configuration in the interference degree table 165 according to the present embodiment.
The interference degree table 165 determines the degree of interference for each frequency channel in the wireless communication system 1 having 13 frequency channels including 1CH, 2CH,... The value used at this time is stored as an “interference degree reference value”.
The interference degree reference value is a received signal strength (RSSI: Received Signal Strength Indicator) obtained from the result of carrier sensing performed on all frequency channels by the channel scanning unit 123, the number of SSIDs, the number of STAs, or a combination thereof. Value shall be used. Here, an example is shown in which the received signal strength is used as an interference degree reference value.

FIG. 8 is a diagram illustrating an example of a data configuration of information elements in a beacon frame according to the present embodiment.
The AP allocates data used for frequency channel control to an “Information Element (information element)” included in the beacon, and transmits and receives the beacon. Thereby, the AP obtains information necessary for frequency channel control between the APs.
For example, as illustrated in FIG. 8, the beacon control unit 121 assigns MAC address information of the parent AP and the next parent AP to the item “Vendor-Specific-content”, thereby transmitting and receiving information through inter-AP communication. In the example, parent AP: 00: 1A: 2B: 3C: 4D: 5E (parent AP information) and next parent AP: 00: 1A: 2B: 3C: 4D: 6E (next parent AP information) are allocated. As described above, the parent AP information and the next parent AP information assigned to the “Vendor-Specific-content” of the beacon are used in the parent AP child AP control process described later with reference to FIG.
In addition, the beacon control unit 121 assigns the number of STAs belonging to the AP for each SSID, that is, for each AP in the present embodiment, to the item “Vendor-Specific-content”. In the example, “SSID01: 3STA, SSID02: 4STA” indicating that the number of STAs belonging to the AP having the SSID name “SSID01” is 3 and the number of STAs belonging to the AP having the SSID name “SSID02” is four. Assigned.

FIG. 9 is a flowchart for explaining the parent AP child AP control processing in the present embodiment.
First, for example, the access points 100 and 200 are activated by the user (step S101).
The channel scanning unit 123 performs a regular channel scan and performs carrier sense for all frequency channels (step S102).
The parent AP child AP control unit 125 reads the carrier sense result (step S103). Here, when there are other APs 100 and 200 that perform communication, the beacon transmitted to the other AP and received by the own AP is included in the carrier sense result.

The parent AP child AP control unit 125 determines whether or not a beacon including parent AP information is included in the carrier sense result (step S104).
When a beacon having parent AP information is included (step S104: YES), it is determined whether parent AP information is received from two or more APs (step S105).
When the parent AP information is received from two or more APs (step S105: YES), the own AP belongs to the parent AP having the stronger radio field intensity. That is, the own AP is set as a child AP of the parent AP (step S106).
The parent AP information is registered in the parent AP management DB 161 (step S107), and the process ends.

When the beacon having parent AP information is not included in the process of step S104 (step S104: NO), the own AP is set as the parent AP (step S108).
Next, the beacon control unit 121 transmits a beacon including parent AP information (step S109). Then, the next parent AP determination process is executed (step S110), and the process ends. The secondary parent determination process will be described with reference to FIG.

  If the parent AP information has not been received from two or more APs in the process of step S105 (step S105: NO), the own AP is set as a child AP (step S111). Then, the parent AP child AP control unit 125 registers the parent AP information in the parent AP management DB 161 (step S112), and ends the process.

FIG. 10 is a flowchart illustrating the next parent AP determination process in the parent AP according to the present embodiment.
First, the channel scan unit 123 of the parent AP performs a regular channel scan. That is, carrier sense is executed for all frequency channels (step S201).
The parent AP child AP control unit 125 reads the carrier sense result (step S202).

The parent AP child AP control unit 125 determines whether or not a beacon transmitted by another AP is included in the carrier sense result (step S203).
When a beacon transmitted by another AP is included (step S203: YES), a request signal for requesting the AP having the highest radio field intensity to become the next parent AP is transmitted via the wireless communication unit 110 (step S204). .
The parent AP child AP control unit 125 receives a response signal to the request signal in step S204 via the wireless communication unit (step S205).
And beacon control part 121 transmits a beacon containing parent AP information (Step S206), and ends processing.
In the process of step S203, when the beacon transmitted by another AP is not included in the carrier sense result (step S203: NO), the process returns to step S201.

FIG. 11 is a conceptual diagram of AP control performed by the parent AP in the present embodiment.
In the wireless communication system in which a plurality of APs having different SSIDs exist, an example is shown in which channel 1, channel 6, and channel 11 that do not interfere with each other are used for a plurality of APs. Since it is assumed that the APs have different SSIDs, the number of APs is the number of SSIDs.

  FIG. 11A shows an example in which the child AP desires to change the channel and the channel change is executed as desired. First, the child AP 200 using the channel 6 requests the parent AP 100 to change to the channel 11 with a low degree of interference. Then, the parent AP 100 changes the channel of the child AP to the channel 11 because the number of SSIDs of the channel 11 is less than the upper limit threshold.

  FIG. 11B shows an example in which the child AP desires to change the channel and the channel change is not performed as desired. First, the child AP 200 using the channel 1 requests the parent AP 100 to change to the channel 6 with a low degree of interference. Then, since the number of SSIDs of the channel 6 is the upper limit threshold value, the parent AP 100 responds NG when switching to the channel 6 desired by the child AP 200. Further, the parent AP 100 determines whether or not there is a channel with the number of SSIDs less than the upper limit threshold and a low degree of interference among other channels. As a result of the determination, when the channel 11 satisfies the determination condition, the parent AP 100 instructs the child AP 200 to change the channel to the channel 11.

Details of channel control processing executed by the AP will be described below with reference to flowcharts.
FIG. 12 is a diagram illustrating a flowchart of the child AP channel control process in the present embodiment.
First, the channel scan unit 123 of the child AP performs a regular channel scan. That is, carrier sense is executed for all frequency channels (step S301).
The channel control unit 124 reads the carrier sense result (step S302).

  The channel control unit 124 determines whether the beacon from the parent AP registered in the parent AP management DB is included in the carrier sense result (step S303). When the beacon from the parent AP is not included in the carrier sense result (step S303: NO), the parent AP stop process in the child AP is executed (step S312), and the process proceeds to step S304. The parent AP stop process in the child AP will be described later with reference to FIG.

In the process of step S303, when the beacon from the parent AP is included in the carrier sense result (step S303: YES), the channel interference degree determination unit 126 creates the interference degree table 165 from the carrier sense result, It memorize | stores in the memory | storage part 160 (step S304).
The channel interference level determination unit 126 reads the interference level table 165 from the storage unit 160 (step S305).
The channel interference level determination unit 126 determines whether or not the current channel interference level is greater than the interference level of other channels (step S306).

When the interference level of the current channel is greater than the interference level of the other channel (step S306: YES), the channel interference level determination unit 126 sets the channel with the lowest interference level among the channels to be used as the desired channel for the channel change request ( Step S307).
The channel control unit 124 transmits a channel change request to the parent AP via the wireless communication unit 110 (step S308).
The channel control unit 124 receives a response from the parent AP via the wireless communication unit 110 (step S309).

The channel control unit 124 determines whether or not the response from the parent AP is a change OK (step S310). If the response from the parent AP is OK to change (step S310: YES), the channel control unit 124 changes to the requested channel (step S311) and ends the process.
If the response from the parent AP is not OK in step S310 (step S310: NO), the channel is changed to a channel designated by the parent AP (step S313), and the process is terminated.

FIG. 13 is a flowchart for explaining the parent AP stop process in the child AP according to this embodiment.
First, the channel scan unit 123 performs a regular channel scan. That is, carrier sense is executed for all frequency channels (step S401).
The channel control unit 124 reads the carrier sense result (step S402).

  As a result of executing the carrier sense, the channel control unit 124 updates the AP information included in the received beacon, and determines whether or not the next parent AP is a new parent AP (step S403). When the AP information is updated and the next parent AP is a new parent AP (step S403: YES), the parent AP management DB is updated with new information (step S404), and the process is terminated.

FIG. 14 is a flowchart for explaining the parent AP channel control process in the present embodiment.
First, the channel scan unit 123 performs a regular channel scan. That is, carrier sense is executed for all frequency channels (step S501).
The channel control unit 124 reads the carrier sense result (step S502).
Channel switching upper limit threshold calculation processing is executed (step S503). This process will be described in detail later with reference to FIG.

The channel control unit 124 determines whether there is a channel change request from the child AP (step S504). When there is a channel change request from the child AP (step S504: YES), the channel change request data from the child AP is read (step S505).
Next, the channel control unit 124 reads the channel switching upper limit threshold value from the storage unit 160 (step S506).

  The channel control unit 124 determines whether or not the number of SSIDs in the change request destination channel of the child AP is smaller than the channel switching upper limit threshold (step S507). If the number of SSIDs in the change request destination channel of the child AP is smaller than the channel switching upper limit threshold (step S507: YES), the channel change OK is returned to the child AP (step S508), and the process is terminated.

In the process of step S507, when the number of SSIDs in the change request destination channel of the child AP is equal to or greater than the channel switching upper limit threshold (step S507: NO), the channel control unit 124 creates the interference degree table 165 from the channel scan result, It memorize | stores in the memory | storage part 160 (step S509).
The channel control unit 124 reads the interference degree table 165 from the storage unit 160 (step S510).

  The channel control unit 124 determines whether or not there is a channel whose SSID number is smaller than the channel switching upper limit threshold and whose interference level is lower than that of the request source channel in channels other than the request destination (step S511). In a channel other than the request destination, when there is a channel whose SSID number is smaller than the channel switching upper limit threshold and the interference level is lower than the request source channel (step S511: YES), the channel control unit 124 moves to the child AP to the desired channel. NG is returned as NG (step S512). Then, the child AP is instructed to change the channel to a channel whose number of SSIDs is smaller than the channel switching upper limit threshold and the degree of interference is lower than the request source channel (step S513), and the process is terminated.

  In the process of step S511, when there is no channel whose SSID number is smaller than the channel switching upper limit threshold and whose interference level is lower than that of the request source channel in the channel other than the request destination (step S511: NO), the channel control unit 124 In response to the channel change NG to the child AP (step S514), the process is terminated.

  In the above description, the method of comparing the number of SSIDs with the channel switching upper limit threshold has been described, but the present invention is not limited to this. As will be described later with reference to FIG. 16, there are a plurality of patterns for calculating the number of SSIDs. There is also a method of comparing the number of STAs with the channel switching upper limit threshold. When determining channel switching, these patterns may be combined, or the patterns may be executed in a predetermined order.

FIG. 15 is a conceptual diagram of an AP channel switching upper limit threshold calculation pattern in the present embodiment.
FIG. 15A shows a pattern in which the parent AP 100-1 calculates the number of SSIDs of all APs existing in the own cell. Specifically, the parent AP 100-1 performs a carrier scan on all frequency channels, and calculates the total number of SSIDs of all APs existing in the own cell from information included in the received beacon. Here, all the APs present in the own cell mean, for example, even if a child AP 200-4 belonging to another parent AP 100-2 as shown in FIG. 15A, the parent AP 100-1 If it exists in the cell, the number of SSIDs is to be calculated. That is, the child APs 200-1 to 200-4 are all APs existing in the cell of the parent AP 100-1.
Since each AP is premised on setting different SSIDs, the number of APs, that is, the number of SSIDs.

  FIG. 15B shows a pattern in which the parent AP 100-1 calculates the number of SSIDs of child APs belonging to the own AP. Specifically, the parent AP 100-1 performs carrier scan on all frequency channels, and the number of SSIDs of the child APs 200-1, 200-2, 200-3 belonging to the own AP from the information included in the received beacon. Is calculated.

  FIG. 15C shows a pattern in which the parent AP 100-1 calculates the number of STAs connected to the own AP and the number of STAs connected to the child AP belonging to the own AP. Specifically, the parent AP 100-1 performs carrier scan on all frequency channels, and belongs to the own AP, the number of STAs 300-1 and 300-2 connecting to the own AP from the information included in the received beacon. The number of STAs 300-3, 300-4, and 300-5 connected to the child APs 200-1 and 200-2 is calculated.

FIG. 16 is a flowchart for describing channel switching upper limit threshold calculation processing in the present embodiment.
First, the channel scan unit 123 performs a regular channel scan. That is, carrier sense is executed for all frequency channels (step S601).
The channel control unit 124 reads the carrier sense result (step S602).
The channel control unit 124 reads the channel switching upper limit threshold calculation pattern setting file 166 from the storage unit 160 (step S603).

The channel control unit 124 determines whether or not the pattern for calculating the number of all SSIDs in the own cell is set to be valid (step S604). When the pattern for calculating the number of all SSIDs in the own cell is set to be valid (step S604: YES), the SSID of the own AP and the total number of all SSIDs included in the received beacon are calculated (step S605). ).
The channel control unit 124 divides the calculated number of SSIDs by the number of used channels as a channel switching upper limit threshold A and stores it in the storage unit 160 (step S606).
If the pattern for calculating the number of all SSIDs in the own cell is not set to be valid in the process of step S604 (step S604: NO), the process proceeds to step S607.

The channel control unit 124 determines whether or not the pattern for calculating the number of SSIDs of the parent AP (own AP) and the child AP is set to be valid (step S607). When the pattern for calculating the number of SSIDs of the parent AP and the child AP is set as valid (step S607: YES), the SSID of the own AP and the total number of SSIDs included in the beacon received from the child AP are calculated (step S607). S608).
The channel control unit 124 divides the calculated number of SSIDs by the number of used channels as a channel switching upper limit threshold value B and stores it in the storage unit 160 (step S608).
If the pattern for calculating the number of SSIDs of the parent AP and the child AP is not set to be valid in the process of step S607 (step S607: NO), the process proceeds to step S610.

The channel control unit 124 determines whether or not the pattern for calculating the number of STAs belonging to the parent AP (own AP) and the number of STAs belonging to the child AP is set to be valid (step S610). When the pattern for calculating the number of STAs belonging to the parent AP and the number of STAs belonging to the child AP is set to be valid (step S610: YES), the number of STAs belonging to the parent AP and the beacon received from the child AP are included. The total number of child APs to be registered is calculated (step S611).
The channel control unit 124 divides the calculated number of STAs by the number of used channels as a channel switching upper limit threshold C, stores it in the storage unit 160 (step S612), and ends the process.
If the pattern for calculating the number of SSIDs of the parent AP and the child AP is not set to be valid for the processing in step S607 (step S610: NO), the processing ends.

FIG. 17 is a sequence diagram illustrating the parent AP takeover process when the parent AP is stopped in the present embodiment.
First, when a function stop process is executed according to a user operation, for example, the parent AP transmits a parent AP function stop notification notifying that the own AP stops the function to the next parent AP (step S701).
Upon receiving the parent AP function stop notification from the parent AP, the next parent AP transmits a parent AP function stop response to the parent AP (step S702).
Upon receiving the parent AP function stop response from the next parent AP, the parent AP stops the AP function (step S703).
Next, the next parent AP sets its own AP as a new parent AP (step S704).
Then, the new parent AP detects the AP having the strongest radio wave intensity within its own cell range from the result of the regular channel scan (step S705) (step S706).

The new parent AP transmits a next parent AP request for requesting the detected AP to become a new next parent AP (step S707).
The AP that has received the next parent AP request transmits a next parent AP request response to the new parent AP (step S708), and sets its own AP as the new next parent AP (step S709).
The new parent AP that has received the next parent AP request response broadcasts a beacon including parent AP information and next parent AP information (step S710).
The new next parent AP broadcasts a beacon including parent AP information and next parent AP information in the same manner as the new parent AP (step S711).
When the child AP receives the beacon including the parent AP information and the next parent AP information in the channel scan periodically executed (step S712), the child AP updates the parent AP information and the next parent AP information (step S713).

FIG. 18 is a sequence diagram for explaining the parent AP takeover process when the parent AP is abnormally stopped in the present embodiment.
While the parent AP is operating normally, the next parent AP receives the beacon including the parent AP information and the next parent AP information by the periodic channel scan (step S801) (step S802).
When a failure or the like occurs and the parent AP stops abnormally, the AP function abnormally stops (step S803).
If the next parent AP does not receive the AP function stop notification from the parent AP and does not receive the beacon including the parent AP information by the periodic channel scan (step S804) (step S805), the next AP becomes the new parent AP. Setting is made (step S806).
The new parent AP detects the AP having the strongest radio wave intensity within the range of its own cell from the result of the regular channel scan (step S807) (step S808).

Next, the new parent AP transmits a next parent AP request for requesting the detected AP to become a new next parent AP (step S809).
The AP that has received the next parent AP request transmits a next parent AP request response to the new parent AP (step S810), and sets its own AP as the new next parent AP (step S811).
The new parent AP that has received the next parent AP request response broadcasts a beacon including parent AP information and next parent AP information (step S812).
The new next parent AP broadcasts a beacon including parent AP information and next parent AP information in the same manner as the new parent AP (step S813).
When the child AP receives the beacon including the parent AP information and the next parent AP information in the channel scan periodically executed (step S814), the child AP updates the parent AP information and the next parent AP information (step S815).

FIG. 19 is a conceptual diagram showing channel setting during communication between APs in the present embodiment.
FIG. 19A shows an example in which communication is performed between the AP and the STA. Parent AP 100-1 uses channel 1 to communicate with STA 300-1. The child AP 200-1 belonging to the parent AP 100-1 uses the channel 11 to communicate with the STA 300-2. The child AP 200-2 belonging to the parent AP 100-1 communicates with the STA 300-3 using the channel 6.
FIG. 19B shows an example in which communication is performed between APs. Parent AP 100-1 uses channel 1 to communicate with STA 300-1. The child AP 200-2 belonging to the parent AP 100-1 uses the channel 6 when communicating with the STA 300-3, but is used by the parent AP when communicating between APs as shown in the figure. Communication is performed by changing the frequency channel of the own AP to the frequency channel, for example, channel 1 in the example.

FIG. 20 is a flowchart for describing channel setting control processing during communication between APs according to this embodiment.
While the inter-AP communication is being performed (step S901), the child AP temporarily changes the channel of its own AP to the channel of the parent AP (step S902).
When the communication between the APs ends, the child AP returns the channel of its own AP to the channel that was originally set (step S903), and ends the process.

  As described above, according to the access point in the wireless communication system 1 in the present embodiment, a network in which the access point in the wireless communication system 1 is a parent or a child is formed. The access point can suppress the radio wave interference by using one of the frequency channels that do not interfere with each other according to the current radio wave interference level of the frequency channel. Furthermore, by selecting the frequency channels used by the access points so that many access points or STAs are not concentrated on the same frequency channel, the channels that do not interfere with each other are used, and the reduction in communication throughput is suppressed. In addition, the communication load can be smoothed.

Further, the above-mentioned parent access point smoothes the number of access points using each frequency channel by allocating frequency channels to the child access points based on the number of access points using each frequency channel. And a decrease in throughput of the entire system can be suppressed. The parent access point can also smooth the number of stations using each frequency channel by allocating frequency channels to the child access points based on the number of stations using each frequency channel, A decrease in the throughput of the entire system can be suppressed.
Further, when the above-mentioned parent access point stops, it can take over without stopping network control by predetermining an access point to be the next parent access point.
In addition, the above-described child access point can change the channel used by the parent access point while executing communication between the access points, so that the access point can control the network formed between the parent and child.

  Further, in the above-described embodiment, a method of using a frequency channel in which radio waves do not interfere with each other as a control target has been described. However, the present invention is not limited to this, and for example, other frequency channels may be added to a frequency channel that is practically acceptable even if there is some interference.

In the above-described embodiment, the example in which the SSID is used as the network identification name set as the access point by the user has been described. However, the present invention is not limited to this, and an ESSID (Extended Service Set IDentifier) may be used as a network identification name. The ESSID is an identification name for identifying a network group in a wireless communication system, and is an extension of an SSID that is an identification name of an individual access point so that the same SSID can be set at a plurality of access points.
When ESSID is used as a network identifier, BSSID (Basic Service Set IDentifier) may be used to calculate the number of access points. The BSSID is an identifier for identifying a communication terminal, and usually the same as the MAC address of the network access point is used. That is, it becomes a unique identification name for each access point.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design etc. of the range which does not deviate from the summary of this invention are included.

1 ... Wireless communication system 100, 100-1, 100-2 ... Parent AP
DESCRIPTION OF SYMBOLS 105 ... Antenna 110 ... Wireless communication part 120 ... Communication control part 121 ... Beacon control part 122 ... Timing control part 123 ... Channel scanning part 124 ... Channel control part 125 ... Parent AP child AP control part 126 ... Channel interference degree determination part 160 ... Storage unit 161 ... Parent AP management DB
162 ... SSID number DB in parent cell
163 ... Parent-child SSID number DB
164 ... STA number DB
165 ... Interference degree table 166 ... Channel switching upper limit threshold calculation pattern setting file 200, 200-1, 200-2, 200-3 ... Child AP
300, 300-1, 300-2,..., 300-11 ... STA
400 ... cell

Claims (6)

An access point in a wireless communication system having a plurality of frequency channels,
A channel scan unit that periodically executes a channel scan to detect for each frequency channel whether or not another access point is communicating in addition to its own access point;
When a parent access point is not detected in the channel scan executed at startup, the local access point is set as a parent access point. When the parent access point is detected by the channel scan executed at startup, the local access point is A parent AP child AP control unit as an access point;
When the own access point is a child access point, a channel interference level determination unit that determines the radio wave interference level in the frequency channel based on the channel scan result;
When the local access point is a child access point, the frequency channel is changed to the parent access point when the radio wave interference level in the frequency channel used by the local access point is greater than the radio wave interference level in other frequency channels. Channel control for making a request and assigning a frequency channel to a child access point based on a channel switching threshold in the frequency channel being used and a channel change request from the child access point when the access point is the parent access point And
Equipped with a,
The parent AP child AP control unit, following the timing when the own access point becomes the parent access point, at the earliest channel scan timing, the next AP that becomes the next parent AP after the own device based on the result of the channel scan. Determine the parent AP from other access points,
An access point characterized by that. The access point according to claim 1, wherein the frequency channels assigned to the access point by the channel control unit are the frequency channels that do not overlap each other. The access point according to claim 1, wherein the channel control unit calculates the threshold value based on the number of the access points assigned to each of the frequency channels. The access point according to any one of claims 1 to 3, wherein the channel control unit calculates the threshold based on the number of stations using each of the frequency channels. When the self access point is a child access point, in communication between access points, communication is performed by changing to a channel used by the parent access point only during execution of the communication. 5. The access point according to any one of 4. A method for controlling an access point in a wireless communication system having a plurality of frequency channels, comprising:
A channel scan procedure for periodically executing a channel scan for detecting for each frequency channel whether or not another access point is communicating in addition to its own access point;
When a parent access point is not detected in the channel scan executed at startup, the local access point is set as a parent access point. When the parent access point is detected by the channel scan executed at startup, the local access point is A parent AP child AP control procedure as an access point;
When the access point is a child access point, a channel interference level determination procedure for determining the radio wave interference level in the frequency channel based on the channel scan result;
When the local access point is a child access point, the frequency channel is changed to the parent access point when the radio wave interference level in the frequency channel used by the local access point is greater than the radio wave interference level in other frequency channels. Channel control for making a request and assigning a frequency channel to a child access point based on a channel switching threshold in the frequency channel being used and a channel change request from the child access point when the access point is the parent access point Procedure and
I have a,
In the parent AP child AP control procedure, at the timing of the channel scan that arrives earliest after the time when the own access point becomes the parent access point, the next AP that becomes the parent AP next to the own device based on the result of the channel scan. Determine the parent AP from other access points,
An access point control method characterized by the above.

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