JP5511014B2 - Wireless LAN system, packet distribution method therefor, and wireless LAN access point - Google Patents

Description

  The present invention relates to a wireless LAN system, a packet distribution method thereof, and a wireless LAN access point, and more particularly to a wireless LAN system that can be suitably used in a store such as a supermarket.

  In general, in a POS system or the like, for example, broadcast communication such as multicast or broadcast is used to simultaneously update a database of selling price data on all POS terminals in a store. However, if multicast or broadcast is used in a POS system using a wireless LAN, radio waves are simultaneously transmitted from the wireless LAN access point, causing radio wave interference, and it takes time to update the database or fails to update. There is even a thing.

  The problem of the POS system using this wireless LAN will be described with reference to FIG. FIG. 1 shows an outline of a wireless LAN system arranged in a store or the like. As shown in FIG. 1, in the wireless LAN system, access points 121, 122, and 123 are connected to subordinate POS registers (POS terminals), respectively. A POS terminal 131 is connected to the access point 121, a POS terminal 132 is connected to the access point 122, and POS terminals 133 and 134 are connected to the access point 123.

  When database data is distributed from the store server 11 to all POS terminals by multicast to update the database on each POS terminal, all access points simultaneously transmit radio waves. At this time, if the access point uses the same channel, packet loss due to radio wave interference occurs in communication, and as described above, time is spent on database distribution or distribution failure occurs, resulting in a database on the POS terminal. Update may take time or update may fail.

  On the other hand, examples of systems using a conventional wireless LAN include those described in Patent Documents 1 to 6.

  In Patent Document 1, a wireless router is provided with first communication means for transmitting information data received by a multicast communication method to a wireless terminal based on the unicast communication method, and the wireless terminal receives a unicast communication method from the wireless router. Describes a data communication system provided with a second communication means for supplying information data received in step (1) to a user device based on a multicast communication method. Patent Document 1 aims to reduce packet loss particularly when a data distribution service based on multicast communication is performed on a wireless LAN.

  Patent Document 2 discloses that a broadcast packet as a radio packet by OFDM is simultaneously transmitted to a plurality of mobile terminal stations by taking advantage of characteristics that do not cause interference even if the same OFDM symbol is transmitted at the same time by synchronizing between a plurality of radio base stations. It is described that it is delivered to. The packet identification unit determines whether the packet is a broadcast packet, and the interference detection unit detects whether there is interference. If it is determined that the broadcast packet is interfering, an OFDM symbol synchronized with the interference source based on the information of the synchronization signal receiving unit is transmitted at the synchronization timing.

  In Patent Document 3, when the slave station devices 2a and 2b belonging to the group corresponding to the multicast information received via the line 3a based on the management contents of the management unit by the multicast information transmission unit exist in the communicable region R Only the wireless transmission of the multicast information is described. In Patent Literature 3, useless wireless communication is deleted by a master station device that transmits group multicast information to a slave station device belonging to the group.

  In Patent Document 4, a multicast list indicating the types of multicast frames that the master unit holds at each slave unit side terminal is acquired, and a multicast list table that associates the multicast list with subordinate slave units is created. Describes that only the type of frame registered in is transferred to the handset side. That is, in Patent Document 4, unnecessary multicast frame transfer is suppressed, and traffic in the wireless section is reduced.

  In Patent Document 5, a multicast control module obtains a list of POS registers and channel information subordinate to each access point, and then the multicast control module generates a multicast group composed of access points of different channels from the information. In addition, it is described that radio waves are suppressed by controlling access points belonging to other multicast groups when each multicast is executed.

  In Patent Document 6, when a new AP (access point) is installed, an information signal from a slave station in the area is received to analyze the channel, and the usable channel selection unit does not use it in the area. It describes that two channels are selected and a communication channel and a broadcast signal channel are set. In Patent Document 6, a newly installed AP channel is prevented from causing an interference problem with an adjacent AP channel.

JP 2006-333309 A JP 2000-069033 A JP 2000-324120 A JP 2001-057560 A JP 2009-055268 A JP 2002-217917 A

  As described above, multicast and broadcast can shorten the communication time by broadcast delivery as a LAN, but as a wireless LAN is a communication that simultaneously transmits radio waves, there may be a decrease in communication quality due to radio wave interference, On the other hand, communication may be time consuming and delivery failure may occur. Further, in a system with a large number of access points, there is a limit to suppression of radio wave interference due to channel arrangement of access points, and it is difficult to solve problems such as delivery failure.

  On the other hand, Patent Document 1 converts a multicast distributed from a server into a unicast at an access point. However, since the probability that the access points simultaneously transmit radio waves is reduced, radio interference can be avoided. However, when there are a large number of clients, unicast performs communication for the number of clients, and as a result, distribution takes time.

  Japanese Patent Laid-Open No. 2004-228561 is to suppress radio wave interference by synchronizing radio waves at each access point and transmitting radio waves of the same OFDM symbol, but is limited to a modulation method called OFDM.

  Further, the method of Patent Document 3 is a technique in which multicast is not transmitted when there is no client within the communication range of the access point, and the method of Patent Document 4 stores the type of multicast that the client needs in advance. This is a technique that prevents unnecessary multicast from flowing to the client. However, in the methods of Patent Documents 3 and 4, when a POS terminal exists within the communication range of each access point and a necessary multicast is sent to these POS terminals, the multicast is not suppressed and the radio wave interference suppressing effect is obtained. I can't get it.

  Patent Document 5 is a method in which each access point uses a different channel in each multicast group, and the influence of radio wave interference can be reduced. However, the method of suppressing radio wave interference is different from the present invention. .

  Patent Document 6 is a method of automatically determining a channel to be used when a new AP is installed. However, when there are a large number of access points installed, all channels are filled with existing access points and can be selected. In some cases, the channel cannot be selected, and radio wave interference cannot be avoided.

  As described above, the methods disclosed in Patent Documents 1 to 6 have problems such as time-consuming radio wave distribution, limited use for a specific modulation method called OFDM, and the expectation of the effect of suppressing radio wave interference. It has been difficult to solve problems such as quality degradation or delivery failure.

  An object of the present invention is to provide a wireless LAN system, a packet distribution method therefor, and a wireless LAN access point that can reliably remove the influence of radio wave interference and improve packet transmission efficiency.

The wireless LAN system according to the present invention is a wireless LAN system that has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals, respectively. Means for determining a distribution order of distributing the multicast packet or broadcast packet of the access point for each combination of wireless LAN access points that can be determined not to interfere with each other based on a distance between the wireless LAN access points; When a packet or broadcast packet is received, the multicast packet or broadcast packet is temporarily stored, and the earliest wireless LAN access according to the distribution order is stored. A combination of points and means for delivering the terminal under a multicast packet or broadcast packet to said storage in order, wherein the wireless LAN access point to a wireless LAN access point as a representative for each combination to determine one of the respective The distribution order is determined between the wireless LAN access points that are representative of the combinations, and the wireless LAN access point that is representative of the respective combinations is distributed to the other wireless LAN access points of the respective combinations. It is characterized by notifying the order .

The packet distribution method according to the present invention is a packet distribution method for a wireless LAN system that has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals, respectively. A wireless LAN access in which the distribution order determining means can determine that the distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point does not interfere with each other based on the distance between the wireless LAN access points. Determining for each combination of points, and when the packet distribution means receives the multicast packet or broadcast packet, the multicast packet or broadcast packet Tsu preparative temporarily stored, viewed including the steps of: delivering to a terminal under the multicast packet or broadcast packet to said storage from a combination of the wireless LAN access point the earliest in accordance with the distribution order in the order, the wireless LAN One representative wireless LAN access point is determined for each combination of access points, the distribution order is determined between wireless LAN access points that are representative of the respective combinations, and the wireless that is representative of the respective combinations is determined. The LAN access point notifies the determined distribution order to the other wireless LAN access points in each combination .

A program according to the present invention has a plurality of wireless LAN access points, and causes a computer to function as a wireless LAN system that distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals. A wireless LAN access, which is a program and can determine that a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point does not interfere with each other based on a distance between the wireless LAN access points. Means for determining each point combination; when the multicast packet or broadcast packet is received, the multicast packet or broadcast packet Store the door temporarily and means for delivering the terminal under a multicast packet or broadcast packet to said storage from a combination of the wireless LAN access point the earliest in accordance with the distribution order in the order, and by function, the wireless LAN One representative wireless LAN access point is determined for each combination of access points, the distribution order is determined between wireless LAN access points that are representative of the respective combinations, and the wireless that is representative of the respective combinations is determined. The LAN access point notifies the determined distribution order to the other wireless LAN access points in each combination .

  According to the present invention, radio wave interference between wireless LAN access points can be reliably removed. As a result, there is no increase in communication time or delivery failure, and transmission efficiency can be improved.

1 is a diagram showing an outline of a wireless LAN system according to the present invention. 1 is a block diagram showing an embodiment of a wireless LAN access point according to the present invention. FIG. It is a flowchart explaining the procedure which determines the packet delivery order of the wireless LAN system which concerns on this invention. It is a flowchart explaining the packet delivery procedure of the wireless LAN system which concerns on this invention.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a schematic configuration of a wireless LAN system according to the present invention. First, as illustrated in FIG. 1, the store server 11 is a server disposed in a store such as a supermarket, for example. A plurality of wireless LAN access points 121 to 123 are connected to the store server 11, and subordinate POS registers (POS terminals) are connected to the wireless LAN access points 121 to 123. In the following description, “wireless LAN access point” may be abbreviated as “access point”.

  In the example of FIG. 1, a POS register 131 is connected to the wireless LAN access point 121, a POS register 132 is connected to the wireless LAN access point 122, and POS registers 133 and 134 are connected to the wireless LAN access point 123. The number of wireless LAN access points and the number of POS registers under the wireless LAN access points are not limited to those shown in FIG. In the following embodiment, the wireless LAN system shown in FIG. 1 is arranged in a store such as a supermarket or a convenience store, and an example of the wireless LAN system in the store will be described.

  FIG. 2 is a block diagram showing an example of the wireless LAN access points 121 to 123 used in the wireless LAN system shown in FIG. In this embodiment, as will be described later, each wireless LAN access point has a function of generating a distribution order (distribution number) of its own access point and a function of acquiring and storing the distribution order of all access points of the wireless LAN system. The multicast packet or the broadcast packet that is temporarily buffered is distributed according to the distribution order.

  In addition, each wireless LAN access point generates its own distribution order, shares its distribution order with all the wireless LAN access points in the wireless LAN system, and temporarily receives a multicast packet or a broadcast packet when receiving a multicast packet or a broadcast packet. After ringing, packet delivery is performed in order from the earliest access point in the delivery order. The order of packet distribution may be from an access point with a small distribution order, or from an access point with a large distribution order. When delivering packets in accordance with the delivery order, it may be determined in advance whether to deliver from the smallest delivery order or from the largest delivery order.

  Normally, a wireless LAN access point supports an inter-access point communication protocol called IAPP (Internet Access Point Protocol) /IEEE802.11f, and each wireless LAN access point is in the same segment (in the system to which it belongs). ) Wireless LAN access point.

  In addition, for example, a stand-alone wireless LAN access point stores the connection status of subordinate clients (terminals), and each access point determines how many subordinate terminals are connected to each access point and which terminal is connected. You can know if it is connected. Further, by transmitting this information to the store server 11, the store server 11 side can also know the connection information of each access point terminal.

  On the other hand, the controller type wireless LAN access point stores which client (terminal) is connected to which access point by the controller (store server 11) in the center of the network. Therefore, by transmitting this connection information from the store server 11 to each access point, each access point can know how many terminals are connected to each access point and which terminal is connected. . Therefore, terminal connection information for each access point can be known at the store server 11 and each wireless LAN access point. In general, the system to which the access point belongs is a network composed of the same segment in the network, specifically, a system having an access point in a store such as a supermarket, a server, a POS terminal, etc. Say.

  Next, a specific configuration and operation of the present embodiment will be described. First, the configuration of the wireless LAN access point shown in FIG. 2 will be described. Each of the access points 121 to 123 includes a bridge unit 21 having a packet filtering function, a random number generation unit 23 that generates an access point distribution order, and an access point distribution order storage that stores the distribution order of all access points in the wireless LAN system. A DB (database) 24, a distribution packet temporary storage buffer 25 for temporarily storing received distribution packets from the store server 11, a packet distribution control unit 22 for performing packet distribution control, and the like are provided. The wired LAN interface 31 is an interface with the store server 11, and the wireless LAN interface 32 is an interface with a POS terminal.

  FIG. 3 is a flowchart for explaining the procedure for determining the packet distribution order of the access point. A method for determining the packet distribution order of access points in the wireless LAN system will be described with reference to FIGS. Hereinafter, for example, the operation of the access point 121 among the plurality of access points 121 to 123 illustrated in FIG. 1 will be described, but the operation of other access points is the same.

  For example, the access point 121 generates a distribution order using the random number generation unit 23 after activation, and notifies the other access points 122 and 123 of this using IAPP (inter-access point protocol). , 123 also acquires the respective delivery order (S301). The other access points 122 and 123 similarly generate the distribution order. The determination of the first distribution number of the access point is not limited to a random number. For example, the MAC address of the access point may be used as the distribution order, or any other method may be used.

  When the distribution order is determined, the access point 121 stores its own distribution order and other distribution orders acquired from the other access points 122 and 123 in the access point distribution order database 24 (S302). Next, the distribution order of the own access point and the distribution order of the access points acquired from the other access points 122 and 123 are compared (S303), and the distribution order that is the same as the own distribution order is acquired from the other access points. If they do not exist in the order (No in S303), the processing for determining the distribution order of the own access point 121 is terminated.

  On the other hand, when the same distribution order as the distribution order of the access point of the self exists in the distribution order acquired from other access points (Yes in S303), the distribution order is generated again using the random number generation unit 23, Notify other access points (S304). Then, the processing from S302 is performed again, the generated distribution order is stored in the access point distribution order storage database 24, and the access point distribution order generated in S303 and the access points acquired from the other access points 122 and 123 are stored. Compare the delivery order of. By repeating the random number generation, storage, notification, and comparison in this manner, the packet delivery order is determined so that the delivery order of its own access point will not be the same as the delivery numbers of other access points.

  FIG. 4 is a flowchart for explaining the packet distribution procedure of the access point. A procedure for distributing the multicast packet or broadcast packet of the access point will be described with reference to FIGS. The access point 121 monitors whether a packet to be distributed has been transmitted from the store server 11 using the filtering function of the bridge unit 21 (S401). That is, it is monitored whether a multicast packet or broadcast packet to be distributed has been transmitted from the store server 11.

  When a multicast packet or broadcast packet subject to distribution control is transmitted from the store server 11 (Yes in S401), the packet is temporarily stored in the distribution packet temporary storage buffer 25 (S402). Next, the access point 121 monitors the distribution completion status of other access points using IAPP (S403), and determines whether the distribution order of its own access point 121 is based on the distribution completion notification from the other access points ( S404).

  That is, it waits for the distribution of all access points smaller than the distribution order of its own access point to be completed (in this case, packet distribution is performed from the access point whose distribution order is small), and distribution of its own access point 121 When the order comes (Yes in S404), a process of distributing the multicast packet or broadcast packet stored in the distribution packet temporary storage buffer 25 to the subordinate POS terminal 131 is started (S405). When packet distribution is completed, IAPP is used to notify the other access points 122 and 123 of the completion of distribution (S406), and the distribution process is terminated. The other access points 122 and 123 perform the packet distribution process in the same manner.

  Each access point notifies the other access points of the completion of delivery even if the packet delivery to all of the subordinate POS terminals is not completed after a certain time has elapsed since the packet delivery was started.

  In addition, after the multicast / broadcast packet is distributed from the store server 11 to each access point, transmission / reception is performed only between the access points until the multicast / broadcast ends. At that time, subsequent packet distribution to all access points is not performed until packet distribution to all POS terminals under all access points is completed. Alternatively, the subsequent packet distribution to each access point is not performed until the packet distribution to all POS terminals under the access point is completed.

  In the present embodiment, the distribution order of wireless LAN access points that distribute multicast packets or broadcast packets is determined, and multicast packets or broadcast packets are distributed in order from the earliest wireless LAN access point in accordance with the distribution order. The influence of radio wave interference between LAN access points can be reliably removed. As a result, there is no increase in communication time or delivery failure, and transmission efficiency can be improved.

  In addition, since packets are distributed from each wireless LAN access point to subordinate POS terminals in accordance with the distribution order, the wireless LAN system having a large number of wireless LAN access points can be used regardless of the number of access points in the wireless LAN system. Can also be suitably used. Furthermore, since it does not depend on the modulation method, it can be applied to wireless LAN systems of various methods such as IEEE802.11a, IEEE802.11b, IEEE802.11g, and IEEE802.11n.

  In the above embodiment, the packet distribution order is determined between the wireless LAN access points, and the other access points are notified that the packet distribution of their own access points is completed. However, the present invention is not limited to this. Absent. For example, the store server 11 may determine the distribution order of the access points in the system, and distribute packets to the subordinate POS terminals in order from the earliest access point in accordance with the distribution order.

  At that time, each access point notifies the store server 11 that the packet distribution is completed, and the store server 11 instructs the next access point to perform packet distribution based on the packet distribution completion notification. In this way, each access point delivers packets from the earliest access point to the subordinate POS terminals in order according to the delivery order under the control of the store server 11. The store server 11 determines the distribution order of each access point so that the distribution order of each access point does not overlap.

  Here, normally, in the wireless LAN system of FIG. 1, multicast / broadcast packets are distributed in the order of store server 11 → access point → POS terminal. At this time, when the packet distribution is completed, a distribution completion notification is transmitted from the POS terminal to the store server 11 via the access point by unicast. The distribution completion notification is transmitted for each POS terminal, and it is monitored whether the distribution completion notification is transmitted from all POS terminals at the store server or the access point.

(Second Embodiment)
The packet distribution order of wireless LAN access points does not have to be determined for each access point as shown in the first embodiment, and may be determined for each combination of access points that do not interfere with radio waves, for example.

  Hereinafter, specific examples of this method will be described. As a method of determining a combination of access points where radio wave interference does not occur, for example, (1) a method of determining a combination according to the channel of the access point, and (2) between access points A method for determining the combination based on the distance of the will be described.

  (1) A method of determining a combination of access points that do not cause radio wave interference depending on the channel of the access point will be described.

For IEEE802.11b / g wireless LAN,
(A) 1, 6, 11ch access points are extracted and set as group 1.
(B) The 2, 7, 12ch access points are extracted and set as group 2.
(C) The access points of 3, 8 and 13ch are extracted and set as group 3.
(D) The access points of channels 4, 9, and (14) are extracted and set as group 4.
(E) The 5 and 10 ch access points are extracted and set as group 5.
(F) Next, the packet distribution order of the groups 1 to 5 is determined, and multicast packets or broadcast packets temporarily stored in order from the group of the earliest wireless LAN access point are distributed to the subordinate POS terminals in accordance with the distribution order. .

  However, channels 1 to 13 are only for EEE802.11b / g wireless LAN, and channel 14 is only for IEEE802.11b. For example, the store server 11 determines a combination of access points where radio wave interference does not occur, and the store server 11 notifies which group each access point belongs to. Furthermore, the store server 11 determines one access point that represents the group for each group, and notifies this to each access point. The same applies to the following method.

For IEEE802.11a wireless LAN,
(A) One access point is extracted from each of the channels 36, 40, 44, 48, 52, 56, 60, and 64ch to form group 1.
(B) One access point is extracted from each channel of the remaining access points to form group 2. This is continued until there are no access points, and the access points are grouped.
(C) Next, the distribution order of the groups 1 to N thus grouped is determined, and similarly, the multicast packet or broadcast temporarily stored in order from the group of the earliest wireless LAN access point according to the distribution order. The packet is distributed to the subordinate POS terminal.

(2) Next, a method for determining a combination of access points that do not cause radio wave interference according to the distance between the access points will be described. For example, when determining a combination in the case where 10 access points are arranged in series at equal intervals such as (1 2 3 4 5 6 7 8 9 10),
Assume that the access points 1, 4, 7, and 10 are at a distance that does not interfere, the access points 2, 5, and 8 are at a distance that does not interfere, and the access points 3, 6, and 9 are at a distance that does not interfere. that time,
(A) Groups 1, 4, 7, and 10 are group 1.
(B) Groups 2, 5, and 8 are group 2.
(C) Groups 3, 6, and 9 are group 3.
(D) Next, the distribution order of the access points of the groups 1 to 3 grouped in this way is determined, and similarly, the multicast temporarily stored in order from the group of the earliest wireless LAN access point according to the distribution order. The packet or broadcast packet is distributed to the subordinate POS terminal.

Also, for example, as shown below, 10 access points are arranged in parallel with 2 units as one group (1, 2 is one group, 3, 4 is one group,...), And each group is in series at equal intervals. If placed in
1 3 5 7 9
2 4 6 8 10
It is assumed that (1, 2) and (7, 8) are at a distance that does not interfere, and (3,4) and (9, 10) are at a distance that does not interfere. that time,
(A) One from (1, 2) and one from (7, 8) are extracted and set as group 1.
(B) The remaining one is extracted from (1, 2) and the remaining one is extracted from (7, 8) to form group 2.
(C) One from (3, 4) and one from (9, 10) are extracted to form group 3.
(D) The remaining one is extracted from (3, 4) and the remaining one is extracted from (9, 10) to form group 4.
(E) Next, the access point distribution order of the remaining access points 5 and 6 and groups 1 to 4 is determined, and similarly, the multicast temporarily stored in order from the group of the earliest wireless LAN access point according to the distribution order. The packet or broadcast packet is distributed to the subordinate POS terminal.

  In this embodiment, the distribution order is determined for each access point that does not interfere with radio waves. However, when determining the distribution order between access points, it is determined between the representative access points of each group, The representative access point notifies this to the group access point. Also, the distribution status of other access points may be monitored at each access point, or at the representative access point of each group, and the distribution order from the representative access point of the group May be notified to an access point in the group. In addition, notification of the end of distribution to other access points after distribution may be performed at each access point, or notification from each access point to the representative access point of the group and from the representative access point of the group You may make it notify to the representative access point of another group. Other configurations and operations are the same as those in the first embodiment.

  In this way, when packet delivery is performed for each combination of access points where radio wave interference does not occur, the POS terminal database update processing, etc. can be speeded up compared to when packet delivery is performed for each access point. Can do. Needless to say, combinations of access points that do not cause radio wave interference are not limited to the above examples, and there are various methods.

  The wireless LAN system and wireless LAN access point of the above embodiment can be realized by hardware, but the computer-readable recording program for causing the computer to function as the wireless LAN system or wireless LAN access point It can also be realized by reading from the medium and executing it. The packet distribution method of the above embodiment can be realized by hardware, but can also be realized by a computer reading a program for causing the computer to execute the method from a computer-readable recording medium and executing the program.

  Moreover, although a part or all of the said embodiment can be described also as the following additional remarks, it is not restricted to the following.

(Supplementary Note 1) A wireless LAN system that has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals,
Means for determining a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point;
When the multicast packet or broadcast packet is received, the multicast packet or broadcast packet is temporarily stored, and the stored multicast packet or broadcast packet is distributed to subordinate terminals in order from the earliest wireless LAN access point according to the distribution order. Means to
A wireless LAN system comprising:

  (Supplementary note 2) The wireless LAN system according to supplementary note 1, wherein a distribution order of the multicast packet or broadcast packet of the wireless LAN access point is determined for each wireless LAN access point.

  (Supplementary note 3) The wireless LAN system according to supplementary note 1, wherein the distribution order of the multicast packet or broadcast packet of the wireless LAN access point is determined for each combination of wireless LAN access points that do not interfere with radio waves.

  (Supplementary note 4) The wireless LAN system according to supplementary note 3, wherein a combination of the wireless LAN access points not causing radio wave interference is determined by a distance between the wireless LAN access points or a channel of the wireless LAN access point.

(Supplementary Note 5) Means for generating a distribution order for distributing multicast packets or broadcast packets to subordinate terminals;
Means for obtaining a delivery order from another access point, and determining a delivery order of its own access point so that the generated delivery order and the delivery order obtained from the other access point are not the same order;
Means for temporarily storing the multicast packet or broadcast packet when the multicast packet or broadcast packet is received, and distributing the stored multicast packet or broadcast packet to subordinate terminals when the determined distribution order has arrived;
Means for transmitting a packet delivery completion notification to the other access point after the stored multicast packet or broadcast packet has been delivered to the subordinate terminal;
A wireless LAN access point comprising:

(Supplementary note 6) A packet distribution method for a wireless LAN system, which has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals,
A step of determining a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point;
When the packet distribution means receives the multicast packet or broadcast packet, it temporarily stores the multicast packet or broadcast packet, and stores the stored multicast packet or broadcast packet in order from the earliest wireless LAN access point according to the distribution order. Delivering to the devices under it,
A packet delivery method comprising:

  (Supplementary note 7) The packet delivery method according to supplementary note 6, wherein a delivery order of the multicast packet or broadcast packet of the wireless LAN access point is determined for each wireless LAN access point.

  (Supplementary note 8) The packet delivery method according to supplementary note 6, wherein the delivery order of the multicast packet or broadcast packet of the wireless LAN access point is determined for each combination of wireless LAN access points that do not interfere with radio waves.

  (Supplementary note 9) The packet distribution method according to supplementary note 8, wherein a combination of the wireless LAN access points not causing radio wave interference is determined by a distance between the wireless LAN access points or a channel of the wireless LAN access point.

(Supplementary Note 10) A program for causing a computer to function as a wireless LAN system that has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals,
The computer,
Means for determining a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point;
When the multicast packet or broadcast packet is received, the multicast packet or broadcast packet is temporarily stored, and the stored multicast packet or broadcast packet is distributed to subordinate terminals in order from the earliest wireless LAN access point according to the distribution order. Means to
Program to make it function.

  (Supplementary note 11) The program according to supplementary note 10, wherein the distribution order of the multicast packet or broadcast packet of the wireless LAN access point is determined for each wireless LAN access point.

  (Additional remark 12) The program of Additional remark 10 characterized by determining the delivery order of the said multicast packet or broadcast packet of the said wireless LAN access point for every combination of the wireless LAN access point which does not interfere with an electromagnetic wave.

  (Supplementary note 13) The program according to supplementary note 12, wherein a combination of the wireless LAN access points that do not interfere with radio waves is determined by a distance between the wireless LAN access points or a channel of the wireless LAN access point.

(Supplementary Note 14) A program for causing a computer to function as a wireless LAN access point,
The computer,
Means for generating a distribution order for distributing multicast packets or broadcast packets to subordinate terminals;
Means for obtaining a delivery order from another access point, and determining a delivery order of its own access point so that the generated delivery order and the delivery order obtained from the other access point are not the same order;
Means for temporarily storing the multicast packet or broadcast packet when the multicast packet or broadcast packet is received, and distributing the stored multicast packet or broadcast packet to subordinate terminals when the determined distribution order has arrived;
Means for transmitting a packet delivery completion notification to the other access point when the stored multicast packet or broadcast packet is delivered to the subordinate terminal;
Program to make it function.

  The present invention can be suitably used, for example, for database update in a POS terminal of a large-scale wireless LAN system.

21 Bridge unit 22 Packet distribution control unit 23 Random number generation unit 24 Access point distribution order storage DB (database)
25 Distribution packet temporary storage buffer 31 Wired LAN interface 32 Wireless LAN interface 11 Store server 121-123 Wireless LAN access point 131-134 POS register (POS terminal)

Claims (3)

A wireless LAN system that has a plurality of wireless LAN access points, and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals ,
Means for determining a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point for each combination of wireless LAN access points that can be determined not to interfere with each other based on a distance between the wireless LAN access points; ,
When the multicast packet or broadcast packet is received, the multicast packet or broadcast packet is temporarily stored, and the stored multicast packet or broadcast packet is subordinated in order from the combination of the earliest wireless LAN access points according to the distribution order. Means for delivering to the terminal;
With
One representative wireless LAN access point is determined for each combination of the wireless LAN access points, the distribution order is determined between the wireless LAN access points that are representative of the respective combinations, and the representative of the respective combinations The wireless LAN system in which the wireless LAN access point becomes a notification of the determined distribution order to the other wireless LAN access points in the respective combinations. A packet distribution method for a wireless LAN system that has a plurality of wireless LAN access points, and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals,
A combination of wireless LAN access points that allows the distribution order determining means to determine that the distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point does not interfere with each other based on the distance between the wireless LAN access points A step to decide for each,
When the packet distribution means receives the multicast packet or broadcast packet, temporarily stores the multicast packet or broadcast packet, and stores the multicast packet stored in order from the combination of the earliest wireless LAN access points according to the distribution order. Delivering a broadcast packet to a subordinate terminal;
Only including,
One representative wireless LAN access point is determined for each combination of the wireless LAN access points, the distribution order is determined between the wireless LAN access points that are representative of the respective combinations, and the representative of the respective combinations The packet distribution method , wherein the determined wireless LAN access point notifies the determined distribution order to the other wireless LAN access points in each combination . A program for causing a computer to function as a wireless LAN system that has a plurality of wireless LAN access points and distributes multicast packets or broadcast packets from the plurality of wireless LAN access points to subordinate terminals,
The computer,
Means for determining a distribution order of distributing the multicast packet or broadcast packet of the wireless LAN access point for each combination of wireless LAN access points that can be determined not to interfere with each other based on a distance between the wireless LAN access points; ,
When the multicast packet or broadcast packet is received, the multicast packet or broadcast packet is temporarily stored, and the stored multicast packet or broadcast packet is subordinated in order from the combination of the earliest wireless LAN access points according to the distribution order. Means for delivering to the terminal;
To function ,
One representative wireless LAN access point is determined for each combination of the wireless LAN access points, the distribution order is determined between the wireless LAN access points that are representative of the respective combinations, and the representative of the respective combinations The program for the wireless LAN access point that has become to notify the other wireless LAN access points of each combination of the determined distribution order .

Images