WO2009094033A1

WO2009094033A1 - Electronic shelf label management method and system

Info

Publication number: WO2009094033A1
Application number: PCT/US2008/052024
Authority: WO
Inventors: Yasushi Yamao; Satoshi Takahishi; Akihiko Fukasawa
Original assignee: Optoelectronics Co., Ltd.; The University Of Electro-Communications; Opticon, Inc.
Priority date: 2008-01-25
Filing date: 2008-01-25
Publication date: 2009-07-30
Also published as: JP2011510596A; JP5191549B2

Abstract

An electronic shelf management system includes a server and a plurality of base station, each associated with a group of electronic shelf labels (ESLs). Each base station communicated wirelessly with the ESLs in its group, all of which are all within the operating range of the base station. Preferably, the server communicates with different base stations in repetitive, non-overlapping time periods.

Description

ELECTRONIC SHELF LABEL MANAGEMENT METHOD AND SYSTEM

BACKGROUND OF THE INVENTION

The present invention relates generally to a system for wirelessly managing a plurality of remote data devices and a method for use therein. More particularly, the invention is applicable to managing electronic shelf label (ESL) systems of the type commonly used in supermarkets and department stores.

Electronic shelf labels (ESLs) find use in merchandising establishments and warehouses to display pricing and other information and to manage inventory. For example, in a supermarket, ESLs might be mounted visibly on the shelves for different items. As item prices change, the new prices can be displayed "instantaneously". Typically, ESLs are clustered in groups, each group is serviced wirelessly by a respective base station, and the base stations are connected to an ESL server. A base station may, for example, communicate with the ESLs via radio. Many factors interfere with the reliable operation and management of ESLs in such a system. For example, the physical construction and layout of the establishment can present transmission and reception difficulties between the base stations and the ESLs. These may arise from the physical construction of the premises or the operation of the ESLs. For example, it is known that standing waves may arise within physical locations, creating dead spots for transmission and reception. In addition, ESLs may be at various distances from their respective base station, and the more remote units may operate marginally. It is also important to be able to detect poor operation or failure of an ESL as soon as possible.

Broadly, it is an object of the present invention to alleviate or eliminate the shortcomings of existing systems and methods for managing wireless remote data devices. It is specifically contemplated that communication failures due to physical construction and layout of a site will be minimized or avoided.

It is an object of the present invention to improve the reliability of data communication within a site that is prone to the generation of standing waves at typical carrier frequencies for such systems. It is another object of the invention to improve the reliability of data communication with ESL units that are the most remote from a base station for their group or which overlap the ranges of different base stations.

It is another aspect of the invention to improve the reliability and speed of detection poor operation or failure of ESL units.

It is also an object of the present invention to provide an improved wireless remote communication system and method which reliable and convenient in use, yet relatively inexpensive.

SUMMARY OF THE INVENTION

In accordance with the present invention, a wireless communication system for remote data devices, such as an electronic shelf management system includes a server and a plurality of base stations, each associated with a group of data devices, such as electronic shelf labels (ESLs). Each base station communicates wirelessly with the ESLs in its group, all of which are within the operating range of the base station. Preferably, the server communicates with different base stations in repetitive, non-overlapping time periods.

In accordance with an aspect of the invention, the data devices carry on a two way communication with a base station. Should they receive data correctly, they respond with an acknowledge signal. Should the data not be received correctly, I will make a further attempt until the data is received correctly or until it has been received incorrectly a predetermined number of times. Preferably, each time data is re-transmitted to an ESL, it is done at a different carrier frequency. Preferably, the communication from an ESL to its base station is delayed in the case of failures, until there is a successful reception or the predetermined numbers of attemps have been made. A single signal from the base station to the server may then combine the results of all attempts for a single or plural ESLs. Preferably, a base station will attempt to transmit to an ESL three times, preferably with carrier frequencies of 2.4 one GHz, 2.45 GHz and 2.49 GHz. Preferably, the server will control the carrier frequencies applied to particular ESLs by the base stations, based upon historical data regarding the effectiveness or ineffectiveness of certain carrier frequencies for the ESLs. In accordance with another aspect of the invention, ESLs which are in the range of a plurality of base stations are given identification (ID) in each base station. Under control of the server, when data communication fails or is marginal in one base station, communication may be attempted in another base station. This not only improves reliability of communication, but permits maintenance of the best available communication through adaptive control. In conjunction with this feature, it is contemplated that intelligent power control of base stations may be utilized with respect with ESLs having distance problems. The server would have a history of the success and power levels for various base stations with distant ESLs and, in addition to switching ESLs between base stations would control the power of the signal provided by the base station to those ESLs.

In the flow chart of FIG. 4, the base station is illustrated as reporting to the server after it has addressed all of the ESLs. Those skilled in the art will appreciate that it will also be possible to report on individual ESLs in real time. In that case, a report would be sent to the server after each of blocks 110 and blocks 116, before returning to block 112, and bock 112 will go directly to block 122.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing brief description and further objects, features, and advantages of the present invention would be understood more completely from the following detailed description of presently preferred, but nonetheless illustrative, embodiments in accordance with the present invention, with reference being had to the accompanying drawings, in which:

FIG. 1 is a functional block diagram of a system S embodying the present invention; FIG. 2 is a timing chart illustrating how N groups of data devices communicate in accordance with one aspect of the invention;

FIG. 3 is timing chart illustrating how a base station and its ESLs communicate interactively in accordance with another aspect of the invention;

FIG. 4 is a flow chart useful for providing more detailed explanation of a preferred communication process in accordance with the invention; FIG. 5 is a schematic diagram of illustrating a method for improving data reception by fringe ESLs, in accordance with another aspect of the invention;

FIG. 6 is a schematic representation of a preferred method for dealing with the occurrence of a standing wave in a site containing a system embodying the invention; and FIG.7 is a timing chart illustrating the operation of an alternate embodiment for a system in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the drawings, FIG. 1 is a functional block diagram of a system S embodying the present invention. The system comprises a server 10 and base stations 1...N, each associated with an ESL group (groups 1...N). Each base station communicates wirelessly with a plurality of ESLs. For example, base station 1 is dedicated to ESLs 1-1 through 1-m, base station 2 is dedicated to ESLs 2-1 through 2-n, and base station N is dedicated to ESLs N-I through N-p. Typically, each ESL is associated with a respective article, which is on a shelf or in a location serviced by the ESL.

The base stations have nominal, associated operating ranges R₁... R_N AS may be seen ESL 1-m is at the edge of range Ri and overlaps slightly into range R₂

In accordance with one aspect of the present invention, the different groups communicate in repetitive non-overlapping, dedicated periods, in order to avoid interference between them. For example, FIG. 2 is a timing chart illustrating the N groups communicating in this manner. Those skilled in the art will appreciate that where the ESLs of two groups are so far apart that there is not likely to be any interference between the signals in the two groups, they may transmit simultaneously. In FIG. 2, it may be seen that data transmission in group 2 will not start until data transmission in group 1 ends. Typically, the time delay between consecutive group transmissions would be in the order of .1 seconds, so that one round of transmission to all N groups will be completed in just a few seconds, even if many groups exist.

In accordance with another aspect of the present invention, the ESLs acknowledge receipt of new data. This is illustrated in the timing chart of FIG. 3, illustrating a data update for a base station 22 which includes three ESLs , 24 , 26, and 28. Initially, server 10 transmits three sets of data, D l, D_2 and D_3 containing new information for ESLs 24, 26 and 28, respectively. This data is received by base station 22, which forwards the data to the respective ESLs. With ESLs 24 26 and, 28 receiving the data at consecutive times. At 21, 23 and 25, ESLs 24, 26, and 28, respectfully, transmit an ACK (acknowledge) signal to base station 22 indicating that they have received new data (assuming that they did receive the data correctly), and base station 22 then signals the acknowledge information to ESL server 10 , where it is stored in appropriate storage 27 . Techniques for error detection, which would be performed at the ESLs before an ACK signal is sent, are well known in the art. FIG. 4 is a flow chart useful for providing a more detailed explanation of the transmission process just described. The process starts at block 100, and data is sent from the server to each base station at block 102. The remaining steps illustrate the operation of an individual base station, but all base stations can be assumed to operate in a similar matter. At block 104, the base station addresses the first ESL, and it sends data to that ESL at blocks 106. The ESL, upon correctly receiving the data, sends an acknowledgement signal (ACK) back to the base station.

At block 108, the base station performs a test to determine whether it has received an ACK signal from the ESL. If so, it records a success for that ESL at block 110, and control is transferred to block 112. Should the base station determine at block 108 that it has not received an ACK signal from the ESL, a test is performed at block 114 to determine whether the data has been sent to that ESL i times (the system selects an appropriate value for i, preferably 3). If it is determined at block 114 that the data has been sent i times, a failure is recorded for that ESL at block 116, and control is transferred to block 112. Should it be determined that block 114 that the data has not been sent i times, control transfers to block 106, where the base station sends the data to the ESL an additional time.

At block 112, a test is performed to determine whether all ESLs have been addressed. If not, control transfers to block 118 where the base station addresses the next ESL and then to block 106 for data transmission to the new ESL. Should it be determined at block 112 that all ESLs have been addressed, this means that the data has been sent to each ESL and success or failure has been recorded. Control is then transferred to block 120 where the base station prepares a report and sends it to the server. The process then ends at block 122.

By the process illustrated in FIG. 4, each base station has received data from the server and has transmitted it to each of its ESLs. It has determined whether an ESL actually received the data and, if it did not, retransmitted the data to the ESL a predetermined number of times before declaring a failure. The results of the process were then reported to the server. In accordance with the present invention, various steps may then be taken to achieve reception by any ESL that failed to receive the data.

Referring to FIG. 1, it will be noted that ESL 1-m is at the fringe of the range Ri of group 1 , but it is also within the range R₂ of group 2, at the fringe of group 2. The schematic diagram of FIG. 5 illustrates a method for improving data reception by fringe ESLs, such as ESL 1-m. Basically, the ESL is registered with and given an identification (ID) in each of the groups, for example an ID 40 in group 1 and an ID 42 is group 2. Should data transmission fail in the first group, it will be attempted again in the second group. Those skilled in the art will appreciate that an ESL can have an ID in any number of adjacent groups. That is, it is not limited to two groups. In each case, as an ESL is addressed to additional groups, the likelihood of correct reception of data increases.

It is contemplated that, in conjunction with registering an ESL with different base stations, intelligent control of the transmission power of the base stations by the server can be simultaneously utilized. For example, when transmission to an ESL is switched from one base station to another, an adjustment in transmission power level would be made, based upon accumulative history. Thus, the server would control the base stations for group 1 and group 2 in the above example to use the best transmission power for an ESL when it is switched between the two groups. In accordance with another aspect of the present invention, special steps are taken to achieve the reception of data by an ESL which is in a "dead spot." One reason for the occurrence of such dead spots is that transmission at certain frequencies will cause a standing wave to arise as a result of the structure of the establishment. If the standing wave happens to exhibit a trough at the location of an ESL, reception by that ESL may be marginal or impossible. FIG. 6 is a schematic representation of a method for dealing with this problem. A base station 30 is attempting to send data to an ESL 32. In accordance with one aspect of the invention described above, base station 30 might attempt transmission i (for example 3) times if it does not receive an ACK signal from the ESL. In accordance with a further aspect of the present invention, each time base station 30 retransmits the data to ESL 32, it does so at a different carrier frequency. For example, the default transmission frequency might be f 1. Should base station 30 fail to receive an ACK signal, the retransmission of data would occur at frequency f2, and a further retransmission would occur at f3, etc. Since the occurrence of dead spots is primarily a frequency phenomenon, it is likely to be eliminated by changing the carrier frequency. Preferably, the three frequencies are 2.41 GHZ, 2.45 GHZ and 2.49 GHZ. When the technique of FIG.6 is utilized and base station 30 transmits to ESL 32 more than one time, it will receive a success or failure response with respect to each frequency. Preferably, when the base station reports back to the server, it will send a single, combined signal representing the success or failure responses with respect to each frequency. Those skilled in the art will also appreciate that, if ESL 32 is failing to receive the data because of interference from nearby equipment, changing the transmission frequency is also likely to reduce or eliminate that interference. In other words, the present technique should improve data transmission whenever failures are based upon a frequency phenomenon. Those skilled in the art will also appreciate that, should it be determined that a particular ESL has a consistently improved reliability of reception at a particular frequency, the respective base station could be adaptively controlled to transmit to that ESL at a carrier frequency which works well the most consistently. Similarly, an ESL could be controlled and so as not to send at a frequency that has been found to be ineffective. Typically, the server would have a record of such information would control the base station accordingly.

FIG.7 is a timing chart illustrating an alternate embodiment in accordance with the present invention. This should be compared to the timing chart of FIG. 3, and the operation of the system is similar except as explained below. In this case, more power efficient operation of the system is obtained by permitting the base stations and the ESLs to operate in a "sleep" mode when transmission and reception of data are not necessary. This is accomplished through the use of a beacon signal, which precedes any other information sent from server 20 to base station 22. After the communication process, such as that of FIG. 4, is completed, a base station and its ESLs will time out and drop into a sleep mode. When server 20 transmits a beacon signal 29, the base station will awake and relay a beacon signal to each of its ESLs 24, 26, 28. The base station and its ESLs are then in a standby mode, and when server 20 thereafter sends the new data, operation will proceed as previously described with respect to the timing chart of FIG. 3. It will be appreciated that, through the use of the beacon signal, the base station and the ESLs will be asleep, except during infrequent occasions when data updating is necessary, achieving a substantial saving of energy. Preferably, the beacon signal is built on a time base controlled in relationship to an accurate reference clock, such as one sent via GPS. It is contemplated that the beacon signal could include more than simply a start signal. For example, when retransmission of data are done at different frequencies, as illustrated in FIG. 6, ACK signals storage 27 will have a history of which transmission frequencies operate best for each ESL. The beacon signal could also include information from the base stations regarding intelligent power control. Prior to generating the beacon signal at the particular base station , the server could therefore prepare instructions for base station regarding which nominal frequencies are to be used for transmission to each ESL and the sequence of frequencies to be used for retransmissions. These instructions could then be incorporated in the beacon signal, so that when the new data is received, a base station will be preset to transmit to each of its ESLs with the optimum frequencies. In FIG. 7 (and in FIG. 3), each ESL is illustrating as reporting an ACK signal in the instances in which multiple transmissions to an ESL are utilized to improve reliability of reception, for example, as illustrated in FIG. 6, it will be appreciated that an ESL may, in fact, be reporting a failure (NACK signal) at one or more of the transmission frequencies. For efficiency of operation, the base station could send a single signal combining the information (ACK or NACK) relating to all of the frequencies transmitted to a particular ESL.

Although preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that many additions, modifications and substitutions are possible, without departing from the disclosed invention as defined by the accompanying claims. For example, the actual pricing data to be conveyed to the ESL devices may be set at the server, or if desired, at the base stations. The Communications between the ESL devices and the base stations and server may use any protocol, and the system may operate using one or more servers.

Claims

WHAT IS CLAIMED;

1. A system for wireless communication with and control of remote data devices located at a site, comprising:

a computing apparatus defining a server;

a plurality of base stations under control of the server, each base station having a wireless communicating range and being constructed to transmit and receive information wirelessly, a group of the base stations with overlapping ranges communicating with the server during repetitive, non-overlapping time periods;

a plurality of remote data devices, each within the range of at least one base station and being constructed for two-way wireless communication with a base station, the data devices being assigned to groups based upon their physical location within the site, each base station communicating with one of the groups.

2. The system of claim 1 wherein the data devices are electronic shelf labels, and wherein the communications may facilitate changing of pricing displayed.

3. The system of claim 1 wherein a data device is constructed to send a signal to a base station regarding success or failure to receive information sent from the base station to the data device, the base station being constructed to retransmit the information to the data device up to a predetermined number of times when reception by the data device fails.

4. The system of claim 3, wherein a base station is constructed to report to the server regarding the success or failure of transmission to the data devices in its group, the base station reporting regarding multiple transmissions to a data device in a single, combined signal.

5. The system of claim 3 wherein the base station sends the information to the data device at an assigned frequency, the frequency being changed under control of either the server or a base station when a re-transmission is attempted.

6. The system of claim 5 wherein a base station transmits to a data device up to three times at respective frequencies of 2.41. GHz, 2.45 GHz, and 2.49 GHz.

7. The system of claim 5, wherein a base station is constructed to report to the server regarding the success or failure of transmission to the data devices in its group, the base station reporting regarding multiple transmissions to a data device in a single, combined signal, the server saving information regarding the success or failure of the various frequencies.

8. The system of claim 1 wherein one of the data devices is in the range of a subgroup of the base stations, the one data device being registered with and recognized by each of the base stations in the subgroup, the server being constructed to control the subgroup so that the one data device can be switched between the base stations of the subgroup and moved selectively from one to another to improve the reliability of communication.

9. The system of claim 8 wherein base stations in the subgroup are constructed to have their transmission power to a base station controlled by the server.

10. The system of claim 1 at least some of the base stations and data devices are normally in a sleeping, powered down state, the server including a beacon signal generator which sends a beacon signal to base stations when communication with data devices is to ensue, the base stations responding to the beacon signal by powering up and sending a relayed beacon signal to data devices in their group, the data devices receiving the relayed beacon signal powering up into a state where they are ready for communication.

11. The system of claim 10 wherein a data device is constructed to send a signal to a base station regarding success or failure to receive information sent from the base station to the data device, the base station being constructed to retransmit the information to the data device up to a predetermined number of times when reception by the data device fails.

12. The system of claim 11 wherein the base station sends the information to the data device at an assigned frequency, the frequency being changed under control of a base station or information provided by the server in the beacon signal when a re-transmission is attempted.

13. The system of claim 10 wherein one of the data devices is in the range of a subgroup of the base stations, the one data device being registered with and recognized by each of the base stations in the subgroup, the server being constructed to control the subgroup via information transmitted in the beacon signal so that the one data device can be switched between the base stations of the subgroup and moved selectively from one to another to improve the reliability of communication.

14. In a system for wireless communication with and control of remote data devices located at a site, the system including a computing apparatus defining at least one server, a plurality of base stations under control of the server, each base station having a wireless communicating range and being constructed to transmit and receive information wirelessly, and a plurality of remote data devices, each within the range of at least one base station and being constructed for two-way wireless communication with a base station, the method comprising the steps of:

operating a group of the base stations with overlapping ranges so as to communicate with the server during repetitive, non-overlapping time periods;

controlling each base station so as to communicate with one of the groups; and

assigning the data devices to a group communicating with a particular base station based upon their physical location within the site.

15. The method of claim 14 wherein electronic shelf labels are used as the data devices, and wherein said communications relate to pricing data to be distributed concerning updates to prices of items.

16. The method of claim 14 further comprising operating a data device is to send a signal to a base station regarding success or failure to receive information sent from the base station to the data device, and operating the base station the base station to retransmit the information to the data device up to a predetermined number of times when reception by the data device fails.

17. The method of claim 16 further comprising operating a base station to report to the server regarding the success or failure of transmission to the data devices in its group, the base station base station being operated to produce a single combined signal regarding multiple transmissions to a data device.

18. The method of claim 16 further comprising operating a base station to send the information to the data device at an assigned frequency, and changing the frequency under control of the server when a re-transmission is attempted.

19. The method of claim 16 wherein a base station transmits to a data device up to three times at respective frequencies of 2.41. GHz, 2.45 GHz, and 2.49 GHz.

20. The method of claim 16 further comprising operating a base station to report to the server regarding the success or failure of transmission to the data devices in its group, the base station being operated to report regarding multiple transmissions to a data device in a single, combined signal, and saving in the server information regarding the success or failure of the various frequencies.

21. The method of claim 14 wherein one of the data devices is in the range of a subgroup of the base stations, further comprising registering one data device with each of the base stations in the subgroup so as to be recognized thereby, operating the server to control the subgroup so that the one data device is switched between the base stations of the subgroup and moved selectively from one to another to improve the reliability of communication.

22. The method of claim 21 controlling base stations in the subgroup so as to have their transmission power to a base station controlled by the server.

23. The method of claim 14 wherein at least some of the base stations and data devices are normally in a sleeping, powered down state, further comprising generating at the server a beacon signal for base stations when communication with data devices is to ensue, powering up the base stations responding to the beacon signal and causing them to send a relayed beacon signal to data devices in their group, and powering up data devices receiving the relayed beacon signal into a state where they are ready for communication.

24. The method of claim 23 further comprising operating a data device is to send a signal to a base station regarding success or failure to receive information sent from the base station to the data device, and operating the base station the base station to retransmit the information to the data device up to a predetermined number of times when reception by the data device fails.

25. The method of claim 23 further comprising operating a base station to send the information to the data device at an assigned frequency, and changing the frequency under control of the beacon signal when a re-transmission is attempted

26. The method of claim 23 wherein a base station transmits to a data device up to three times at respective frequencies of 2.41. GHz, 2.45 GHz, and 2.49 GHz.

27. The method of claim 23, wherein the beacon signal is built on a time base related to a reference clock signal.

28. The method of claim 27 wherein the reference clock signal is provided via GPS.

29. The system of claim 10, wherein the beacon signal is built on a time base related to a reference clock signal.

30. The system of claim 29 wherein the reference clock signal is provided via GPS.