JP2010103770A - Communication system, access point manager in communication system, and wireless tag storing method in communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system which appropriately distributes communication load to APs and reduces communication latency. <P>SOLUTION: A wireless tag (Tag1) measures receiving quality of signals from each of access points (AP1 and AP2) (ST11), and then reports the measured receiving quality of each of the APs to an access point manager (APM) (ST12 and ST13). The APM links the synchronizing Tag1 to the synchronized AP2 and registers it into a database, and stores the receiving quality into the database (ST14). If the number of Tags which are linked to the AP2 and registered is equal to or more than a predetermined value (ST18), a wireless tag Tag1 which is selected from the Tags that are linked to the AP2 and registered, and is to be resynchronized to another AP1, and the resynchronization destination AP1 are determined based on the receiving quality (ST19), and a resynchronization command which instructs that the Tag1 that is to be resynchronized is resynchronized with the synchronization destination AP1 is reported (ST20 and ST21). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is, for example, an electronic shelf label system, a plurality of wireless tags, a plurality of access points that can be synchronized with the wireless tag, an access point manager that registers a wireless tag synchronized with the access point in a database, This is a technique suitable for a communication system having

  Conventionally, an electronic shelf label system is used in a supermarket, for example, and manages a large number of wireless tags by a management device. In an electronic shelf label system, generally, a wireless tag (hereinafter referred to as Tag) is wirelessly connected to an access point (hereinafter referred to as AP), and the AP is connected to a management apparatus by wire. The management apparatus is generally called an access point manager (hereinafter referred to as APM).

  In the electronic shelf label system, after a Tag that can rewrite display information is registered in the APM through the AP, the APM accesses the Tag through the AP, so that the display information of the Tag can be rewritten. (For example, refer to Patent Documents 1 to 5).

  In practice, the AP is fixedly installed in the store, and the Tag is semi-fixed (the semi-fixed is not permanently fixed, but is moved infrequently). Here, in order to ensure sufficient communication quality in a wide area called a store, a plurality of APs are installed, and Tag selects one of the plurality of APs as a relay station according to the radio wave environment.

  In such an electronic shelf label system, a different frequency channel (frequency band) is used for each AP. For example, AP1 uses the frequency channel ch1, and AP2 uses the frequency channel ch2 in a band different from the frequency channel ch1.

  In addition, the electronic shelf label system generally employs a beacon synchronization method. In the beacon synchronization method, the Tag can synchronize with each AP by frequency scanning the beacon signals transmitted from a plurality of APs in the order of the channel list, for example, and synchronizing with the beacon signals of each frequency channel. In general, the Tag is scanned in the order of the channel list and synchronized with the AP that has acquired synchronization first or the AP of the frequency channel with the best radio wave state among all frequency channels.

  This beacon synchronization method is useful when the number of tags is as high as tens of thousands to hundreds of thousands. In the beacon synchronization method, the Tag synchronizes with the beacon signal transmitted from the AP, wakes up with the wake-up information included in the beacon signal, and waits for a command from the AP. Such a beacon synchronization method can achieve both point-to-point communication and power saving. In the beacon synchronization method, the AP needs to know which tag is synchronized with itself, and therefore registration processing is necessary. The registration process is generally realized by the following steps [1] to [4].

[1] The AP periodically sends an unregistered call command and waits for a response from the unregistered Tag.
[2] When an unregistered Tag receives an unregistered call command, it returns its ID information.
[3] The AP receives the ID information and recognizes the presence of a tag synchronized with itself.
[4] The AP notifies the Tag that it has been recognized, and the Tag enters the registration state.

  By performing the registration process as described above, the AP can recognize the presence of a tag under its management and can communicate with a specific tag.

  Note that Tag does not respond to an unregistered call command once beacon synchronization is lost once it is in a registered state. Thereby, low power consumption is achieved.

Further, in the conventionally proposed system, the AP notifies the registered Tag information to the APM managing the plurality of APs, and the APM registers the registered Tag information in the database.
JP 2002-304673 A JP 2005-99888 A JP 2002-109177 A JP 2004-265196 A JP-A-9-138892

  By the way, as described above, the beacon synchronization method is a very useful method for communicating with the majority of tags using a plurality of APs, but the concept of load distribution is sufficiently considered in the registration process. Therefore, when there is a bias in the radio wave situation, most tags are synchronized with one AP, and most tags may be registered in association with this one AP.

  Here, since the AP communicates with a plurality of registered tags in a time division manner in its own frequency channel, the number of tags that can be communicated in a certain time is limited. For this reason, when the Tag number registered in association with itself exceeds the Tag number that can be communicated per certain time, there is a drawback that the AP cannot make a round of communication with all the Tag within a certain time.

  The present invention has been made in consideration of such points, and even when a beacon synchronization method is used, a communication system capable of accurately distributing a communication load to an AP and reducing a communication delay, and an access point in the communication system A wireless tag accommodation method in a manager and a communication system is provided.

  One aspect of the communication system of the present invention includes a plurality of wireless tags, a plurality of access points that can synchronize with the wireless tags, and an access point manager that registers a wireless tag synchronized with the access points in a database. In the communication system, each of the plurality of wireless tags measures the reception quality of a signal from each access point, and sends the measured reception quality of each access point to the access point manager via the synchronized access point. The access point manager registers the synchronized wireless tag in association with the synchronized access point and stores the reception quality in the database, and registers the received wireless tag in association with one access point. Based on the received quality. The wireless tag to be resynchronized with another access point and the resynchronization destination access point are determined from the wireless tags registered in association with the one access point, and the resynchronization is performed with the wireless tag to be resynchronized. A configuration is adopted in which a resynchronization command for instructing resynchronization to a previous access point is notified.

  One aspect of the access point manager of the present invention includes a plurality of wireless tags, a plurality of access points to which the wireless tags can be synchronized, and an access point manager that registers a wireless tag synchronized with the access points in a database. The access point manager in a communication system comprising: information on reception quality of a plurality of synchronizable access points in the plurality of radio tags from the plurality of radio tags, and the synchronized radio tag in the database Is stored in association with the synchronized access point and the reception quality is stored, and when the number of wireless tags registered in association with one access point is a predetermined number or more, based on the reception quality, Wireless tag registered in association with the one access point A radio tag to be resynchronized with another access point and a resynchronization destination access point are determined, and a resynchronization command for instructing the radio tag to be resynchronized to resynchronize with the resynchronization destination access point Notify, adopt the configuration.

  One aspect of the wireless tag accommodation method of the present invention includes a plurality of wireless tags, a plurality of access points to which the wireless tags can be synchronized, and an access point manager that registers wireless tags synchronized with the access points in a database. A method of accommodating a wireless tag in a communication system comprising: a reception quality measuring step in which the wireless tag measures reception quality of signals from the plurality of synchronizable access points; and the wireless tag includes the measurement Notifying the access point manager of reception quality information of each access point via the access point having the best reception quality, and the access point manager notifying the database of the reception quality information Corresponding to the access point that notified the reception quality information of the wireless tag The number of registered wireless tags exceeds a predetermined number based on the number of registered wireless tags and the number of wireless tags registered in association with each access point. An access point is detected, and the number of registered wireless tags is registered in association with an access point that exceeds a predetermined number based on reception quality information of each access point notified from the plurality of wireless tags. Determining a wireless tag to be re-synchronized with another access point from among the wireless tags and a re-synchronization destination access point; and the access point manager sets the re-synchronization destination access point to the re-synchronization destination access point. And notifying a resynchronization command for instructing resynchronization.

  According to the present invention, even when the beacon synchronization method is used, it is possible to accurately distribute the communication load on the access point and reduce the communication delay.

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

(1) Configuration (1-1) System Overview FIG. 1 shows an overall configuration of an electronic shelf label system according to an embodiment. In FIG. 1, in order to simplify the drawing and the following description, the number of tags and the number of APs are shown smaller than those in the actual system. As an actual system, a case where there are tens of thousands to hundreds of thousands of tags and a case where about 1 to 100 APs are present is assumed.

  A LAN connection is established between the host computer (Host) 20 and the APM 10, and between the APM 10 and each of the AP1 to AP3. Further, each AP1 to AP3 and each Tag1 to Tag9 are wirelessly connected.

  The Host 20 issues a command to the APM 10 and controls Tag1 to Tag9. The Host 20 is connected to an input device such as a keyboard, and can input setting information of the entire system and display information to be displayed on Tag1 to Tag9, for example.

  The APM 10 performs control and state management of each AP1 to AP3. Further, the APM 10 has a database for storing management information of each AP1 to AP3, communication path information of each Tag1 to Tag9 (information about which AP is synchronized), status information including registration information of each Tag1 to Tag9, and the like. Information management of each AP1 to AP3 and routing to each AP1 to AP3.

  Each of AP1 to AP3 converts message information (data signal) from Tag 20 to Tag 1 to Tag 9 sent via APM 10 into a radio signal and transmits it to Tag 1 to Tag 9. Each AP1 to AP3 has a wireless communication unit, a LAN interface, and the like. AP1 to AP3 transmit a wireless signal to each of Tag1 to Tag9 by the wireless communication unit. AP1 to AP3 receive radio signals from the Tag1 to Tag9 by the radio communication unit.

  Each of Tag1 to Tag9 includes a wireless communication unit and a display device. Each Tag1-Tag9 receives the radio signal from each AP1-AP3 by a radio | wireless communication part. Moreover, Tag1-Tag9 transmits a radio signal to each AP1-AP3 by a radio | wireless communication part.

  In FIG. 1, Tag1, Tag2, and Tag3 are registered in synchronization with AP1 using the frequency channel ch1, and Tag4, Tag5, and Tag6 are registered in synchronization with AP2 using the frequency channel ch2, and Tag7, Tag8, Tag 9 is registered in synchronization with AP3 using frequency channel ch3.

  FIG. 1 shows an example of a tag group that is synchronized and registered with each AP (that is, each frequency channel), and shows an AP or frequency channel that can be actually synchronized and can be registered. is not.

(1-2) Configuration of APM FIG. 2 shows the configuration of the APM 10. The APM 10 is composed of, for example, a computer system, and includes a database 11, a processing unit 12, a communication unit 13, an input device 14, and a display device 15.

  The database 11 stores information on AP and Tag. The processing unit 12 includes a CPU and the like, and executes processing for managing the tag based on a program installed in the storage device 16 in advance. The communication unit 13 is connected to the AP via a network such as a LAN, a WAN, or a dedicated line, and is a device for communicating with the AP. In the case of the present embodiment, the communication unit 13 is connected to the AP via the LAN. The input device 14 includes a mouse, a keyboard, and the like, and is used for inputting various commands and data. The display device 15 includes an LCD, a CRT, and the like, and displays the contents of the database 11 and the like. The storage device 16 includes a hard disk drive and the like, and a program executed by the processing unit 12 is installed.

  FIG. 3 shows the data structure of the database 11. The data in the database 11 mainly includes tag information 11-1 and setting information 11-2. Tag information 11-1 is information for identifying and managing each Tag, and includes, for example, Tag ID, product code, and the like. The setting information 11-2 includes information to be displayed on the Tag such as a product name and a price, and is information that can be set by the APM 10.

  FIG. 4 shows the data structure of the Tag information 11-1. The tag information 11-1 includes UID, SID, GTIN, APID, MID (Model ID), VID (Version ID), battery voltage, AP reception quality information, and the like. The UID is a unique ID assigned to the Tag at the time of manufacture. The SID is an ID used for communication that the APM 10 assigns to the Tag. GTIN is a product code (Global Trade Item Number). The APID is an ID for identifying the AP. The MID is an ID indicating a Tag model. VID is an ID indicating the version of Tag firmware. The battery voltage is information indicating the voltage of the battery built in the Tag.

  In addition, the database 11 stores reception quality information of each AP measured by each Tag as Tag information 11-1. For example, the reception quality information of a plurality of APs that can be synchronized with Tag 1 measured by Tag 1 is stored as reception quality Q 1.

  The APM 10 manages the tag based on the tag information 11-1.

(1-3) Configuration of AP FIG. 5 shows the configuration of APs (AP1 to AP3). The AP includes a communication unit 31, a processing unit 32, a storage unit 33, a wireless communication unit 34, a power supply circuit 35, and a battery 36.

  The communication unit 31 is connected to the APM 10 via a network such as a LAN, a WAN, or a dedicated line, and is a device for communicating with the APM 10. The processing unit 32 is configured by a microcomputer or the like, and executes processing for relaying communication between the APM 10 and Tag based on a program installed in the storage unit 33. The storage unit 33 includes, for example, a rewritable nonvolatile memory such as an EEPROM, a ROM, a RAM, and the like, and stores tag information 11-1 within a communicable range in addition to the communication control program. The wireless communication unit 34 is a device for performing wireless communication with the Tag. The power supply circuit 35 is connected to an AC power supply such as a commercial power supply from the outside, converts the connected AC power supply to a DC voltage, and supplies the drive voltage to the communication unit 31, the processing unit 32, the storage unit 33, and the wireless communication unit 34. Supply. The battery 36 is a rechargeable power storage means such as a Ni-Cd battery, a lithium ion battery, or an electric double layer capacitor. The battery 36 is charged by a DC voltage generated by the power supply circuit 35, and a termination program is executed when the AC power supply is cut off. Drive power is supplied to the communication unit 31, the processing unit 32, the storage unit 33, and the wireless communication unit 34 for a certain period of time so that they can be executed.

(1-4) Configuration of Tag FIG. 6 shows a configuration of Tag (Tag 1 to Tag 9). Tag includes a wireless communication unit 41, a processing unit 42, a storage unit 43, a display device 44, and a battery 45.

  The wireless communication unit 41 is a device that performs wireless communication with the AP.

  The processing unit 42 includes a CPU and the like, and performs communication control with the AP based on a program stored in the storage unit 43 and also performs display control of the display device 44. In addition to this, the processing unit 42 has a function of measuring the reception quality of the signal received from each AP by measuring the signal input from the wireless communication unit 41. In the present embodiment, a received signal strength RSSI (Received Signal Strength Indicator) is calculated as the received quality. For example, LQI (Link Quality Indication) may be calculated as the reception quality. The processing unit 42 sends the calculated received signal strength RSSI of each AP to the wireless communication unit 41. Accordingly, the received signal strength RSSI of each AP is transmitted to the currently synchronized AP via the wireless communication unit 41.

  The storage unit 43 is composed of, for example, a rewritable nonvolatile storage device such as an EEPROM, and a program to be executed by the processing unit 42 is installed, and a Tag ID and a product code are stored therein. . A part of the Tag ID and the product code are registered in advance, and can be changed via the AP. The display device 44 includes an LCD, an EL panel, electronic paper, and the like, and displays a product name, a product code, a price, and the like according to an instruction from the processing unit 42. The battery 45 is a small battery and supplies driving power to the wireless communication unit 41, the processing unit 42, the storage unit 43, and the display device 44.

(2) Operation Next, the procedure of the synchronization / registration process in the electronic shelf label system of the present embodiment will be described with reference to FIG. In FIG. 7, in order to simplify the description, the model will be simplified and a synchronization / registration process between one Tag 1, two APs 1 and 2, and the APM 10 will be described as an example.

  First, in step ST10, each AP1 and AP2 transmits an unregistered call to all the tags. Among the tags that have received this signal, Tag1, which is in an unregistered state, synchronizes with the beacon signal transmitted from each AP1 and AP2 in step ST11, and further measures the received signal quality of the signal from AP1 and AP2. . In the present embodiment, the received signal strength RSSI is measured as the received signal quality. Thereby, in step ST11, the received signal strength RSSI (1) of AP1 and the received signal strength RSSI (2) of AP2 are obtained.

  In step ST12, the registration request is notified from Tag1 to the AP having the largest received signal strength RSSI (the AP to which Tag1 is currently synchronized). In the case of the example of FIG. 7, since RSSI (1) <RSSI (2), a registration request is notified to AP2. This registration request includes the UID of Tag1 and the reception quality of all APs that can be synchronized with Tag1 (RSSI (1) and RSSI (2) in the case of FIG. 7).

  In step ST13, a registration request is notified from AP2 to APM10. This registration request includes the APID of AP2, the UID of Tag1, and the reception quality of all APs that can synchronize with Tag1 (RSSI (1) and RSSI (2) in the example of FIG. 7).

  In step ST14, the APM 10 registers the synchronized Tag 1 in the database 11 in association with the synchronized AP 2 based on the received registration request. In step ST14, the APM 10 stores the received electric field strengths RSSI (1) and RSSI (2) in the database 11.

  In steps ST15 to ST16, a registered message is notified to Tag1 via AP2. In step ST17, Tag1 that has received the registered message enters a registered state.

  In step ST18, the APM 10 detects from the contents of the database 11 an AP whose number of tags registered in association with each AP exceeds a predetermined number. In the example of FIG. 7, it is detected that the number of tags registered in association with AP2 exceeds a predetermined number. The process of step ST18 may be performed at a predetermined cycle or each time the number of tags registered in the database 11 increases to some extent.

  In step ST19, the APM 10 determines a tag to be resynchronized with another AP and a resynchronization destination AP from among the tags registered in association with APs whose registered wireless tags exceed the predetermined number. To do. The determination of the tag to be resynchronized and the AP to be resynchronized is performed based on the reception quality from each AP in each tag collected in the database 11. Specific examples thereof will be described later. FIG. 7 shows an example in which Tag1 is determined as the Tag to be resynchronized and AP1 is determined as the resynchronization destination AP.

  In steps ST20 to ST21, a resynchronization command is notified to Tag1 via AP2. The resynchronization command includes an APID indicating the resynchronization destination AP.

  In Step ST22, Tag1 that has received the resynchronization command resynchronizes with AP1 using a beacon signal from AP1 that is the resynchronization destination.

  In step ST23, unregistered calls are transmitted from the AP1 and AP2. In step ST24, Tag1 notifies the resynchronization destination AP1 of a registration request in response to an unregistered call. In step ST25, the registration request from Tag1 is relayed by AP1 and notified to APM10. In step ST26, the APM 10 registers the resynchronized Tag1 in the database 11 in association with the resynchronized AP1 based on the received registration request.

  Next, a method for determining a tag to be resynchronized and a resynchronization destination AP will be described with reference to a specific example of FIG.

  FIG. 8 shows a state of an AP (frequency channel) that can be synchronized and registered. For example, Tag1, Tag2, and Tag3 are currently registered in synchronization with AP1. APM10 and Host20 recognize that Tag1, Tag2, and Tag3 are under AP1. However, it is assumed that AP1 can transfer data only for one Tag per fixed time. Further, it is assumed that AP2 and AP3 are capable of transferring up to five.

  Therefore, the APM 10 periodically checks the number of tags registered in each AP (corresponding to the process of step ST18), and performs a process for distributing the communication load. First, the APM 10 selects two tags that can be resynchronized with other APs by arranging them in the order of the second RSSI value from among Tag1, Tag2, and Tag3 registered in association with AP1. Then, a resynchronization processing command for designating the second RSSI AP (frequency channel) is issued to the selected Tag.

  In the case of the example in FIG. 8, Tag 3 is in the radio range of AP2, so the second RSSI value is high. Since Tag2 is also in the radio range of AP3, the second RSSI value is high. On the other hand, Tag1 is not in the radio range other than AP1, and the second RSSI value is lower than that of Tag2 and Tag3. Therefore, Tag2 and Tag3 are determined as tags to be re-synchronized, AP3 is determined as a resynchronization destination AP of Tag2, and AP2 is determined as a resynchronization destination AP of Tag3.

  The APM 10 regularly adjusts the number of registered tags to each AP by performing these processes periodically. As a result, the communication load on the AP can be accurately distributed and the communication delay can be reduced.

  The operation of this embodiment is summarized as follows.

  [1] In this embodiment, once a tag is registered in association with a certain AP, there is no problem even if it is synchronized with another AP from the currently registered tags (a communication quality of a certain level or more can be maintained). And a resynchronization command specifying the resynchronization destination AP is notified to those tags. As a result, the number of tags synchronized with each AP is kept below the maximum number of tags that each AP can communicate within a predetermined time, so that communication delay can be reduced.

  In the processing of this embodiment, for example, when the registration limit number for each AP is set in the APM database, and there is a registration request from an unregistered Tag beyond that, simply add another AP to the Tag. Compared with the process of issuing a command to re-synchronize and immediately rejecting new registration requests exceeding the limit number, the connection between AP and Tag is realized, which improves communication quality substantially regardless of the order of registration. it can.

  [2] In this embodiment, before registration, Tag synchronizes with all APs and performs RSSI measurement of all synchronized APs. Finally, Tag is synchronized with the AP having the highest numerical value (communication quality is good) and registered in association with the AP. When the Tag is registered in synchronization with the AP having the highest RSSI, the Tag notifies the APM 10 of the RSSI value having the second highest RSSI and the identification information (APID) of the AP corresponding thereto along with its ID information (UID). Of course, the RSSI value with the highest RSSI and the corresponding AP identification information, the RSSI value with the third highest RSSI, and the AP identification number corresponding thereto may be notified. The APM 10 stores these pieces of information in the database 11. Then, the APM 10 checks each AP at regular intervals, and if the number of tags registered in association with a certain AP exceeds the allowable number, the APM 10 stores the information in the tag registered in association with the AP. The resynchronization command specifying the AP determined based on the RSSI value as the resynchronization destination AP is notified.

  The processing of the present embodiment is substantially the same regardless of the order of the channel list, for example, compared to the case where the Tag scans the channel in the order of the channel list and is registered in association with the AP synchronized first. Connection between AP and Tag that improves communication quality can be realized.

  [3] In the present embodiment, the process of reducing the number of registered tags is performed by selecting an AP having the second highest RSSI value as a resynchronization destination. First, in all the tags registered corresponding to the AP for which the Tag number is to be reduced, the second highest RSSI value is arranged in descending order, and the RSSI value is equal to or higher than the value satisfying the communication condition. The tag to be resynchronized is selected until the registration limit number becomes equal to or less than the specified value. Then, the selected Tag is notified of a command instructing resynchronization with the AP having the second RSSI value. The target Tag is resynchronized with a designated AP (frequency channel) based on the resynchronization command and registered again. As described above, the tag exceeding the registration limit quantity in the AP is reconnected to another AP satisfying the communication condition, so that the communication load between the AP and the tag is reduced and optimized.

(3) Effect As described above, according to the present embodiment, each of the plurality of wireless tags measures the reception quality of the signal from each access point (ST11), and the received reception quality of each access point is measured. To the access point manager via the synchronized access point (ST12, ST13), and the access point manager registers the synchronized wireless tag in the database in association with the synchronized access point and the reception quality. When the number of wireless tags stored and registered in association with one access point is equal to or greater than a predetermined number (ST18), registered in association with the one access point based on the reception quality Wireless tag to be resynchronized with another access point from the wireless tag and the access point to be resynchronized (ST19), and a resynchronization command for instructing resynchronization to the resynchronization destination access point is notified to the wireless tag to be resynchronized (ST20, ST21). Thereby, even when the beacon synchronization method is used, it is possible to realize an electronic shelf label system capable of accurately distributing the communication load to the AP and reducing the communication delay.

(4) Other Embodiments In the above-described embodiment, the case where the present invention is applied to an electronic shelf label system has been described. However, the present invention is not limited to this, and a plurality of wireless tags and wireless tags can be synchronized. The present invention can be widely applied to communication systems having a plurality of access points and an access point manager that registers a wireless tag synchronized with the access point in a database. The present invention is particularly effective when a wireless tag is provided semi-fixed or when a wireless tag is added.

An example of a system to which the present invention can be applied is given below.
・ Safety management system (children's commuting history management, nursing home admission management, prison management, etc.): This system installs multiple APs in the person's movement range, and gives the person a wireless tag to move history and entry / exit It is a system that performs management.

  ・ Asset management system (location of measuring instruments and equipment and management of maintenance information): This system installs multiple APs in the room and attaches a wireless tag to movable equipment (assets). This is a system that manages the location of users, the display of user information, maintenance information, and the like.

  Building air conditioning illuminance management system: This system installs a plurality of APs on each floor, and arranges a wireless tag having sensors such as temperature, humidity and / or illuminance sensor at each measurement point. And it is a system which controls air conditioning and lighting based on the sensor data acquired from each wireless tag.

  Even in the above-described system, when the present invention is applied, the communication load on the AP can be accurately distributed when the number of persons and facilities to be managed increases or the number of sensors is increased, so that communication delay can be reduced. .

  In the above-described embodiment, the case where the APM 10 is provided separately from the host computer (Host) 20 has been described. However, the APM 10 is omitted by providing the host computer (Host) 20 with the function of the APM 10. It is good also as a structure. Further, if the function of the APM 10 is provided in any of the plurality of APs, the APM 10 may be omitted.

  Even when the beacon synchronization method is used, the present invention has an effect of accurately distributing the communication load on the AP and reducing the communication delay, and communicates with a large number of tags using a plurality of APs. Suitable for communication systems.

The figure which shows the whole structure of the electronic shelf label system which concerns on embodiment of this invention. Block diagram showing the configuration of the access point manager (APM) Diagram showing database data structure The figure which shows the data structure of Tag information Block diagram showing the configuration of the access point (AP) Block diagram showing the configuration of Tag The figure which shows the procedure of the synchronization / registration process in the electronic shelf label system of this Embodiment Diagram for explaining a method of determining a tag to be resynchronized and a resynchronization destination AP

Explanation of symbols

10 Access Point Manager (APM)
11 Database 20 Host computer (Host)

Claims (7)

A communication system comprising a plurality of wireless tags, a plurality of access points to which the wireless tags can be synchronized, and an access point manager for registering a wireless tag synchronized with the access points in a database,
Each of the plurality of wireless tags measures the reception quality of a signal from each access point, and notifies the access point manager of the measured reception quality of each access point via the synchronized access point,
The access point manager registers, in the database, the synchronized wireless tag in association with the synchronized access point and stores the reception quality, and the number of wireless tags registered in association with one access point is When the number is equal to or greater than a predetermined number, based on the reception quality, a wireless tag to be resynchronized with another access point among wireless tags registered in association with the one access point and a resynchronization destination access point Determining and notifying a resynchronization command that instructs the radio tag to be resynchronized to resynchronize with the resynchronization destination access point;
Communications system. The access point manager determines, as the resynchronization destination access point, an access point at which the next highest reception quality of the one access point is measured in the wireless tag to be resynchronized.
The communication system according to claim 1. The access point manager determines a radio tag whose reception quality of a predetermined value or more is measured at an access point other than the one access point as the radio tag to be resynchronized.
The communication system according to claim 1. An access point manager in a communication system comprising: a plurality of wireless tags; a plurality of access points that can synchronize with the wireless tags; and an access point manager that registers wireless tags synchronized with the access points in a database,
Receiving reception quality information of the plurality of synchronizable access points in the plurality of wireless tags from the plurality of wireless tags;
In the database, the synchronized wireless tag is registered in association with the synchronized access point and the reception quality is stored, and the number of wireless tags registered in association with one access point is equal to or greater than a predetermined number. In this case, based on the reception quality, a wireless tag to be resynchronized with another access point and a resynchronization destination access point are determined from the wireless tags registered in association with the one access point, and the resynchronization is performed. A wireless tag to be notified of a resynchronization command instructing resynchronization with the resynchronization destination access point;
Access point manager. The resynchronization destination access point is an access point in which the next highest reception quality of the one access point is measured in the wireless tag to be resynchronized.
The access point manager according to claim 4. The wireless tag to be resynchronized is a wireless tag whose reception quality of a predetermined value or more is measured at an access point other than the one access point.
The access point manager according to claim 4. A wireless tag accommodation method in a communication system, comprising: a plurality of wireless tags; a plurality of access points that can synchronize with the wireless tags; and an access point manager that registers a wireless tag synchronized with the access points in a database. ,
A reception quality measuring step in which the wireless tag measures reception quality of signals from the plurality of synchronizable access points;
The wireless tag notifying the access point manager of information of the measured reception quality of each access point via the access point with the best reception quality;
The access point manager registers, in the database, the radio tag that has notified the reception quality information in association with the access point that has notified the reception quality information and stores the reception quality;
The access point manager detects an access point whose number of registered wireless tags exceeds a predetermined number based on the number of wireless tags registered in association with each access point, and is notified from the plurality of wireless tags. Based on the information on the reception quality of each access point, the wireless tag to be resynchronized with another access point from among the wireless tags registered in association with the access points where the number of registered wireless tags exceeds a predetermined number Determining a tag and a resynchronization destination access point;
The access point manager notifying a re-synchronization command to instruct the wireless tag to be resynchronized to resynchronize with the resynchronization destination access point;
A method of accommodating a wireless tag including

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