Field

The present application relates to handling Bluetooth low energy advertisement messages. In particular, although not exclusively, it relates to course tracking of devices in a building or complex of buildings.

Background

Bluetooth Low Energy (BLE) is a new wireless communication technology published by the Bluetooth SIG as a component of Bluetooth Core Specification Version 4.0. BLE is a lower power, lower complexity, and lower cost wireless communication protocol, designed for applications requiring lower data rates and shorter duty cycles. Inheriting the protocol stack and star topology of classical Bluetooth, BLE redefines the physical layer specification, and involves many new features such as a very-low power idle mode, a simple device discovery, and short data packets, etc.

BLE technology is aimed at devices requiring a low power consumption, for example devices that may operate with one or more button cell batteries such as sensors, key fobs, and/or the like. BLE can also be incorporated into devices such as mobile phones, smart phones, tablet computers, laptop computers, desktop computers etc.

Summary

Various aspects of examples of the invention are set out in the claims.

A first aspect of the invention provides apparatus configured to:

scan for Bluetooth low energy advertisement messages for a first period of time and then to cease scanning;

decode an tag identifier from a low energy advertisement message received from a Bluetooth low energy tag during the first period of time;

communicate the tag identifier along with an identifier relating to the apparatus to a server;

after ceasing scanning, wait for a second period of time and then again scan for Bluetooth low energy advertisement messages for a period of time. The apparatus may be configured to repeat scanning for Bluetooth low energy advertisement messages for a period of time and then to cease scanning on a periodic basis, wherein the second period between ceasing scanning and subsequent scanning may be the same for each repeat of the scanning.

The second period of time may have a value between 10 seconds and 300 seconds, optionally between 20 seconds and 200 seconds, and further optionally between 30 seconds and 100 seconds.

The apparatus may be configured to repeat scanning for Bluetooth low energy advertisement messages for the first period of time and then to cease scanning, wherein the first period of time may be the same for each repeat of the scanning.

The first period of time may have a value between 0.1 seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds.

The apparatus may be configured to communicate the tag identifier along with an identifier relating to the apparatus to a server by uploading the tag identifier and identifier relating to the apparatus to a webserver.

The apparatus may be configured to select one Bluetooth low energy advertisement message of multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time, and to decode the tag identifier from the selected Bluetooth low energy advertisement message. This apparatus may be configured to select the one Bluetooth low energy advertisement message of the multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time by selecting the one of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time that has the highest signal strength. Alternatively or in addition, the apparatus may be configured to decode the tag identifier from the selected Bluetooth low energy advertisement message, to communicate the the tag identifier from the selected Bluetooth low energy

advertisement message to the server and to refrain from communicating tag identifiers of other ones of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time.

The apparatus may be configured, if no Bluetooth low energy advertisement messages are received within the first period of time, to refrain from communicating with the server prior to performing a subsequent scan for Bluetooth low energy advertisement messages.

The apparatus may be configured to disable radio data communication resources of the apparatus for a period between communicating the tag identifier and the identifier relating to the apparatus to the server and starting a subsequent scan for Bluetooth low energy advertisement messages.

A second aspect of the invention provides a system comprising apparatus as above and multiple Bluetooth low energy tags.

Each Bluetooth low energy tag may be battery-powered.

Each Bluetooth low energy tag may be configured to transmit Bluetooth low energy advertisement messages periodically. A period between successive Bluetooth low energy advertisement message transmissions may have a value between o.i seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds.

Each Bluetooth low energy tag may be absent of a Bluetooth receiver function.

Each Bluetooth low energy tag may be configured to transmit a tag identifier that is different from the tag identifiers of all other Bluetooth low energy tags in the system.

A third aspect of the invention provides a system comprising apparatus as above or a system as above, and the server.

The server may be configured to monitor information received from the apparatus and to provide a warning when no information has been received from the apparatus for a predetermined period of time. A fourth aspect of the invention provides a non-transitory computer-readable storage medium having stored thereon computer-readable code, which, when executed by computing apparatus, causes the computing apparatus to perform a method comprising:

scanning for Bluetooth low energy advertisement messages for a first period of time and then to cease scanning;

decoding an tag identifier from a low energy advertisement message received from a Bluetooth low energy tag during the first period of time;

communicating the tag identifier along with an identifier relating to the apparatus to a server;

after ceasing scanning, waiting for a second period of time and then again scanning for Bluetooth low energy advertisement messages for a period of time.

A fifth aspect of the invention provides a method comprising:

scanning for Bluetooth low energy advertisement messages for a first period of time and then to cease scanning;

decoding an tag identifier from a low energy advertisement message received from a Bluetooth low energy tag during the first period of time;

communicating the tag identifier along with an identifier relating to the apparatus to a server;

after ceasing scanning, waiting for a second period of time and then again scanning for Bluetooth low energy advertisement messages for a period of time.

The method may comprise repeating scanning for Bluetooth low energy advertisement messages for a period of time and then ceasing scanning on a periodic basis, wherein the second period between ceasing scanning and subsequent scanning may be the same for each repeat of the scanning.

The second period of time may have a value between 10 seconds and 300 seconds, optionally between 20 seconds and 200 seconds, and further optionally between 30 seconds and 100 seconds. The method may comprise repeating scanning for Bluetooth low energy advertisement messages for the first period of time and then ceasing scanning, wherein the first period of time may be the same for each repeat of the scanning.

The first period of time may have a value between o.i seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds.

The method may comprise communicating the tag identifier along with an identifier relating to the apparatus to a server by uploading the tag identifier and identifier relating to the apparatus to a webserver.

The method may comprise selecting one Bluetooth low energy advertisement message of multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time, and decoding the tag identifier from the selected Bluetooth low energy advertisement message.

The method may comprise selecting the one Bluetooth low energy advertisement message of the multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time by selecting the one of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time that has the highest signal strength.

The method may comprise decoding the tag identifier from the selected Bluetooth low energy advertisement message, communicating the the tag identifier from the selected Bluetooth low energy advertisement message to the server and refraining from communicating tag identifiers of other ones of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time.

The method may comprise, if no Bluetooth low energy advertisement messages are received within the first period of time, refraining from communicating with the server prior to performing a subsequent scan for Bluetooth low energy advertisement messages. The method may comprise disabling radio data communication resources of the apparatus for a period between communicating the tag identifier and the identifier relating to the apparatus to the server and starting a subsequent scan for Bluetooth low energy advertisement messages.

The method may comprise each of plural Bluetooth low energy tags transmitting Bluetooth low energy advertisement messages periodically.

A period between successive Bluetooth low energy advertisement message

transmissions may have a value between o.i seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds.

Each Bluetooth low energy tag may be absent of a Bluetooth receiver function.

The method may comprise each Bluetooth low energy tag transmitting a tag identifier that may be different from the tag identifiers of all other Bluetooth low energy tags in the system.

The method may comprise a server monitoring information received from the apparatus and providing a warning when no information has been received from the apparatus for a predetermined period of time.

A sixth aspect of the invention provides a computer program comprising instructions that when executed by a computer apparatus control it to perform the method above.

A seventh aspect of the invention provides apparatus, the apparatus having at least one processor and at least one memory having computer-readable code stored thereon which when executed controls the at least one processor:

to scan for Bluetooth low energy advertisement messages for a first period of time and then to cease scanning;

to decode an tag identifier from a low energy advertisement message received from a Bluetooth low energy tag during the first period of time;

to communicate the tag identifier along with an identifier relating to the apparatus to a server; after ceasing scanning, to wait for a second period of time and then again scan for Bluetooth low energy advertisement messages for a period of time.

The computer-readable code when executed may control the at least one processor to repeat scanning for Bluetooth low energy advertisement messages for a period of time and then to cease scanning on a periodic basis, wherein the second period between ceasing scanning and subsequent scanning may be the same for each repeat of the scanning.

The second period of time may have a value between 10 seconds and 300 seconds, optionally between 20 seconds and 200 seconds, and further optionally between 30 seconds and 100 seconds.

The computer-readable code when executed may control the at least one processor to repeat scanning for Bluetooth low energy advertisement messages for the first period of time and then to cease scanning, wherein the first period of time may be the same for each repeat of the scanning.

The first period of time may have a value between 0.1 seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds.

The computer-readable code when executed may control the at least one processor to communicate the tag identifier along with an identifier relating to the apparatus to a server by uploading the tag identifier and identifier relating to the apparatus to a webserver.

The computer-readable code when executed may control the at least one processor to select one Bluetooth low energy advertisement message of multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time, and to decode the tag identifier from the selected Bluetooth low energy advertisement message.

The computer-readable code when executed may control the at least one processor to select the one Bluetooth low energy advertisement message of the multiple Bluetooth low energy advertisement messages received from multiple Bluetooth low energy tags during the predetermined period of time by selecting the one of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time that has the highest signal strength.

The computer-readable code when executed may control the at least one processor to decode the tag identifier from the selected Bluetooth low energy advertisement message, to communicate the the tag identifier from the selected Bluetooth low energy advertisement message to the server and to refrain from communicating tag identifiers of other ones of the multiple Bluetooth low energy advertisement messages received during the predetermined period of time.

The computer-readable code when executed may control the at least one processor, if no Bluetooth low energy advertisement messages are received within the first period of time, to refrain from communicating with the server prior to performing a subsequent scan for Bluetooth low energy advertisement messages.

The computer-readable code when executed may control the at least one processor to disable radio data communication resources of the apparatus for a period between communicating the tag identifier and the identifier relating to the apparatus to the server and starting a subsequent scan for Bluetooth low energy advertisement messages.

An eighth aspect of the invention provides a system comprising apparatus as above and multiple Bluetooth low energy tags.

Each Bluetooth low energy tag may be battery-powered.

Each Bluetooth low energy tag may be configured to transmit Bluetooth low energy advertisement messages periodically.

A period between successive Bluetooth low energy advertisement message

transmissions may have a value between o.i seconds and 5 seconds, optionally between 0.3 seconds and 3 seconds, and further optionally between 0.5 seconds and 2 seconds. Each Bluetooth low energy tag may be absent of a Bluetooth receiver function.

Each Bluetooth low energy tag may be configured to transmit a tag identifier that is different from the tag identifiers of all other Bluetooth low energy tags in the system.

A ninth aspect of the invention provides a system comprising apparatus as above, and the server.

The computer-readable code when executed may control the server to monitor information received from the apparatus and to provide a warning when no

information has been received from the apparatus for a predetermined period of time.

Bluetooth Low Energy or BLE as used herein denotes Bluetooth Core Specification Version 4.0 or later versions that are backwards-compatible with Version 4.0. A BLE device or component is a device or component that is compatible with Bluetooth Core Specification Version 4.0.

Brief Description Of The Drawings

For a more complete understanding of example embodiments of the present invention, reference is now made to the following descriptions taken in connection with the accompanying drawings in which:

Figure 1 is a schematic diagram of a system according to aspects of the invention including components according to aspects of the invention that operate according to aspects of the invention;

Figure 2 is a flow chart according to aspects of the invention showing steps taken by a device of the system of Figure 1;

Figure 3 is a flow chart according to aspects of the invention showing steps taken by a tag of the system of Figure 1;

Figure 4 is a flow chart according to aspects of the invention showing steps taken by a server of the system of Figure 1; and

Figure 5 is a flow chart according to aspects of the invention showing other steps taken by a server of the system of Figure 1.

Detailed Description Of Various Embodiments The following acronyms are used in the specification and have the meanings referred to:

BLE: Bluetooth Low Energy

BT: Bluetooth

BT SIG: Bluetooth Special Interest Group

Figure l shows a system according to embodiments of the invention. The system 10 includes a first device 11 and a second device 12. It also includes first to nth BLE tags 30a, 30b to 30η. It also includes a server 40, which is a webserver in this example. The first and second devices 11, 12 are mobile or portable and their locations can be tracked. The first and second devices 11, 12 are configured to communicate in a radio network 50. The sever 40 is connected either directly or indirectly with the radio network 50

The first device 11 includes a BLE module 13, which operates according to the BLE standard. Each of the BLE tags 30 also includes a BLE module that operates according to the BLE standard.

Briefly, the BLE tags 30 are based at different locations within a building or complex of buildings and transmit advertisement messages, which have a limited range. Each of the first and second devices 11, 12 is able to receive advertisement messages from the Bluetooth tags 30, decode a tag identifier from a received message, and communicate the tag identifier with an identifier relating to the device 11, 12 to the server 40. Using information received from the devices 11, 12, the server 40 can track at a course level the devices 11, 12 as they reside in and move around the building or complex. The BLE tags 30 are configured such that this is possible without requiring expensive or difficult to maintain tag hardware. On the contrary, the BLE tags 30 may be able to perform the functions required to achieve this using a coin battery or a button battery for many months or even years. This allows a location tracking system to be installed by simply placing low-cost, battery-powered tags at appropriate places in a building or complex, providing a server, and providing BLE devices 11, 12 (such as mobile phones) with a suitable software application.

The first device 11 includes a processor 112. The processor 112 is connected to volatile memory such as RAM 113 by a bus 118. The bus 118 also connects the processor 112 and the RAM 113 to non-volatile memory, such as ROM 114. A communications interface or module 115 is coupled to the bus 118, and thus also to the processor 112 and the memories 113, 114. A BLE module 13 is coupled to the bus 118, and thus also to the processor 112 and the memories 113, 114. An antenna 116 is coupled to the

communications module 115 and the BLE module 13, although each may instead have its own antenna. Within the ROM 114 is stored a software application 117. An operating system (OS) 120 also is stored in the ROM 114.

The first device 11 may take any suitable form. Generally speaking, the first device 11 may comprise processing circuitry 112, including one or more processors, and a storage device 114, 113, comprising a single memory unit or a plurality of memory units. The storage device 114, 113 may store computer program instructions that, when loaded into the processing circuitry 112, control the operation of the first device 11.

The BLE module 13 may take any suitable form. Generally speaking, the BLE module 13 of the first device 11 may comprise processing circuitry, including one or more processors, and a storage device comprising a single memory unit or a plurality of memory units. The storage device may store computer program instructions that, when loaded into the processing circuitry, control the operation of the BLE module 13.

The first device 11 also comprises a number of components which are indicated together at 119. These components 119 may include any suitable combination of a display, a user input interface, other communication interfaces (e.g. wifi, etc.), a speaker, a microphone, and a camera. The components 119 may be arranged in any suitable way.

The second device 12 may be configured and operate in the same way as the first device 11.

The devices 11, 12 may be mobile phones, smart phones, tablet computers, laptop computers etc. The devices 11, 12 may be based around any suitable operating system, for instance the Symbian operating system or Microsoft Windows operating system, although any other operating system may instead be used. The devices 11, 12 may run different operating systems. The tag 30a includes a BLE module 121, an antenna 126 and a battery 130. In the BLE module 121 of the tag 30a, a processor 122, RAM 123, ROM 124, a transmitter 125, software 127 and a bus 128 are constituted and connected in any suitable way. The ROM 124 of the tag 30a also stores a tag identifier 129. The battery 130 may be a coin battery or a button battery, for instance. The battery 130 powers the BLE module 121 and any other components of the tag 30a.

In this example, the transmitter 125 of the BLE module 121 of the tag 30a is solely a transmitter and does not perform receiver functions. The transmitter 125 may include hardware needed for receiving, the receive function being disabled through the software 127. Alternatively, the transmitter 125 may be absent of some of the hardware needed for receiving. Put another way, it may be a transmitter or it may be a transceiver in which the receive functions have been disabled in software.

The tag 30a may take any suitable form. Generally speaking, the tag 30a may comprise processing circuitry, including one or more processors, and a storage device, comprising a single memory unit or a plurality of memory units. The storage device may store computer program instructions that, when loaded into the processing circuitry, control the operation of the tag 30a.

The other tags 30b ... 30η may be configured and operate in the same way as the first tag 30a.

The server 40 includes a processor 412. The processor 412 is connected to volatile memory such as RAM 413 by a bus 418. The bus 418 also connects the processor 112 and the RAM 413 to non-volatile memory, such as ROM 414. A communications interface 415 is coupled to the bus 418, and thus also to the processor 412 and the memories 413, 414. The interface 415 is connected to the radio network 50 in any suitable way, for instance via the Internet or a local network. Within the ROM 414 is stored a software application 417. An operating system (OS) 420 also is stored in the ROM 414. Within the ROM 414 is also stored a location database 422.

An output device such as a display 419 may be provided with the server 40. An input device such as a keyboard 421 may be provided with the server 40. The server 40 may take any suitable form. Generally speaking, the server 40 may comprise processing circuitry 412, including one or more processors, and a storage device 414, 413, comprising a single memory unit or a plurality of memory units. The storage device 414, 413 may store computer program instructions that, when loaded into the processing circuitry 412, control the operation of the server 40.

Some further details of components and features and alternatives for them will now be described.

The computer program instructions 117 may provide the logic and routines that enables the first device 11 to perform the functionality described below. The computer program instructions 117 may be pre-programmed into the first device 11. Alternatively, they may arrive at the first device 11 via an electromagnetic carrier signal or be copied from a physical entity such as a computer program product, a non-volatile electronic memory device (e.g. flash memory) or a record medium such as a CD-ROM or DVD. They may for instance be downloaded to the first device 11 from a server, for instance the server 40 but possibly another server such as a server of an application marketplace or store.

The computer program instructions 417 may provide the logic and routines that enables the server 40 to perform the functionality described below. The computer program instructions 417 may be pre-programmed into the server 40. Alternatively, they may arrive at the first device 11 via an electromagnetic carrier signal or be copied from a physical entity such as a computer program product, a non-volatile electronic memory device (e.g. flash memory) or a record medium such as a CD-ROM or DVD.

The processing circuitry 112, 122, 412 may be any type of processing circuitry. For example, the processing circuitry may be a programmable processor that interprets computer program instructions and processes data. The processing circuitry may include plural programmable processors. Alternatively, the processing circuitry may be, for example, programmable hardware with embedded firmware. The processing circuitry or processor 112, 122, 412 may be termed processing means.

Typically, the BLE modules 13, 121 each comprise a processor coupled connected to both volatile memory and non-volatile memory. The computer program is stored in the non-volatile memory and is executed by the processor using the volatile memory for temporary storage of data or data and instructions.

The term 'memory' when used in this specification is intended to relate primarily to memory comprising both non-volatile memory and volatile memory unless the context implies otherwise, although the term may also cover one or more volatile memories only, one or more non-volatile memories only, or one or more volatile memories and one or more non-volatile memories. Examples of volatile memory include RAM, DRAM, SDRAM etc. Examples of non-volatile memory include ROM, PROM,

EEPROM, flash memory, optical storage, magnetic storage, etc.

Each BLE module 13, 121 may be a single integrated circuits. Each may alternatively be provided as a set of integrated circuits (i.e. a chipset). The BLE modules 13, 121 may alternatively be hardwired, application-specific integrated circuits (ASIC).

The communication interface 115 may be configured to allow two-way communication with external devices and/or networks. The communication interface may be configured to communicate wirelessly via one or more of several protocols such as Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Universal Mobile Telecommunications System (UMTS) and IEEE 802.11 (Wi- Fi). Alternatively or additionally, the communication interface 115 may be configured for wired communication with a device or network.

The apparatus 11, 12, 40, 30 may comprise further optional software components which are not described in this specification since they may not have direct interaction with the features described.

The BLE tags 30 are distributed around a building or premises. For instance a first tag 30a may be located in a canteen, a second tag 30b may be located in a reception area, and so on. The first and second tags 30a and 30b can be referred to as tags 30. Tags 30 do not need to provide complete coverage of a building, but may be provided only at key locations. Advantageously, the key locations in the building include the entries and the exits so that people can be tracked entering and leaving the building. Each of the tags is configured to transmit a BLE advertisement message periodically. The BLE advertisement messages transmitted by a given tag include an identifier that is unique to that tag within the building. The tag identifier transmitted by a tag may be provided in a Device Address field or in a Device Identifier field of an advertising message, according to the BLE specification, or it may take some other form.

The latest version of the BLE specification defines three advertising channels, which serve for device discovery and other broadcasting purpose. According to the BLE specification, packets sent in the advertising channels (index=37, 38 and 39) shall contain the device addresses, which are used to identify a BLE device. The identifier relating to a tag may be a device address included in the Device Address field, or it may be included in a payload of the advertising message.

Operation of the tags 30 will now be described with reference to Figure 3.

The operation starts at step Si. At step S2, an advertisement message is transmitted. The advertisement message is a BLE advertisement message having a form specified by version 4.0 of the Bluetooth specification. According to the standard specification, the message includes four components. These are a preamble, which is one octet or byte in length. The second is an Access Address, which is four octets in length. The third is a packet data unit (PDU). According to the specification, this may be between two and 39 octets in length. The fourth is a cyclic redundancy check (CRC) component. The CRC component is three octets in length. The PDU includes a header and a payload. The header of the PDU includes four bits that denote the PDU type. The value included in the PDU type field of the header of the PDU of the advertising message is selected such as to denote that the advertisement message is suitable for use in determining a course location of mobile devices 11, 12. This may occur in any suitable way, and the PDU type may have a value that is included in version 4.0 of the Bluetooth specification or it may include a value that is currently reserved for future use.

At step S3, a timer is reset and started. At step S4, it is determined whether the timer has expired. If the timer has not expired, step S4 is performed again until it is determined that the timer has expired. Upon detection that the timer has expired, the operation proceeds again to step S2, where another advertisement message is transmitted. The value of the timer that is reset and started in step S3 dictates the interval between transmission of successive advertisement messages in step S2. The value of the timer may take any suitable form. For instance, the value of the timer may be one second, the value may take any value between 0.5 and 2 seconds, or more generally between 0.3 and 3 seconds, or more generally again between 0.1 and 5 seconds.

Operation of the first device 11 will now be described with reference to Figure 2.

The operation starts at step Si. At step S2, the BLE module 13 is enabled and scanning for Bluetooth signals is started. Also at step S2, a first timer is reset and started. The value of the first timer may be, for instance, one second.

At step S3, the first device collects messages that are received by the BLE module 13. Messages that are received are collected by storing them in the ROM 114.

At step S4 it is determined whether the first timer has expired. On a negative determination, the operation returns again to step S3. Upon a positive determination, the operation progresses to step S5. Steps S3 and S4 ensure that messages are collected by the first device 11 for the period whilst the first timer is active.

At step S5, scanning for advertisement messages is stopped. Also, a second timer is reset and started. The second timer is used to determine the time between successive scans for BLE signals by the first device 11. A suitable value for the second timer is, for instance, one minute (60 seconds).

At step S6, the first device 11 identifies the one of the messages that was collected at step S3 that is the strongest. This may for instance comprise the determining the message that is associated with the highest received signal strength, or it may be done in some other suitable way. For instance, it may comprise identifying the message with the lowest bit error rate or the lowest signal to noise ratio.

At step S7, the tag identifier that was present in the strongest message identified at step S6 is uploaded to the server 40 along with an identifier relating to the first device 11. At step S8, radio communication resources of the first device 11 are disabled. Messages that were collected in step S3 are then deleted at step S9.

Finally, at step S10 the first device 11 waits until the second timer expires before the operation returns to step S2. After the tag identifier and the device identifier have been uploaded, messages are deleted and radio resources are unused until the next scanning interval.

A result of operation of the first device 11 as explained with reference to Figure 2 is as follows. In summary, the first device 11 scans for BLE signals for a period of time that is set by the first timer before stopping scanning. Scanning remains switched off for a period of time set by the second timer. As such, the first device 11 is scanning for BLE advertisement messages for a fraction of the total time, and in a periodic way. Of the messages that are received in a scanning interval, an identifier of the tag 30 that transmitted the strongest message is uploaded to the server 40 along with an identification of the first device 11. This allows the server 40 to track the first device 11. No location determination or tracking needs to be performed by the first device 11 itself in allowing the server 40 to track it.

Although the second timer is described as having a value of 60 seconds (one minute), this is just an example. The second timer may have any suitable value instead. For instance, the value of the timer may be between 30 and 100 seconds, or more generally between 20 and 200 seconds, or further generally between 10 and 300 seconds. The shorter the interval between successive scans, which is defined by the second timer, the better tracking of the location of the device 11, 12 will be available. However, this is at the expense of increased power consumption of the device 11, 12 (because more information will need to be uploaded to the server 40) and also at the expense of an additional memory requirement at the server 40 to store the additional received information, at least in embodiments in which historical information is stored at the server 40.

If the first device 11 does not collect any messages at step S3 in a scanning interval, no message is identified as the strongest message in step S6. In this event, step S7 is not performed, that is no data is uploaded to the server 40. Consequently, if the first device 11 is not within range of one of the tags 30 or is unable to receive BLE advertisement messages from one of the tags 30 for some other reason, it does not upload any information to the server. The server 40 can use the absence of information received from a device 11, 12 to issue a warning when a device 11, 12 is not being tracked, as is described below.

The identifier relating to the device 11, 12 may take any suitable form. For instance, it might be a telephone number associated with the device 11, 12, that is it might be a telephone number that is uniquely associated with a subscriber identity module (SIM) card that is included in the device 11, 12. It might alternatively be a part of the telephone number, or it might be a number that is derived from the telephone number. By having the device identifier constructed such that it can be linked to the telephone number of the device 11, 12, the identification of specific users may be performed by the server 40 relatively easily, for instance using a personnel database. Alternatively, using a number from which the telephone number of the device 11, 12 cannot be derived may improve privacy for the user of the device 11, 12. The device identifier may take any suitable form as long as it uniquely identifies the device 11, 12 compared to all other devices that may be tracked within the building.

The uploading step S7 of Figure 2 may be performed in any suitable way. For instance, this may involve a particular uniform resource locator (URL) that is associated with the server 40. For instance, the application 117 stored in the first device 11 may cause the tag identifier and the device identifier to be uploaded to www.noMa.cxim /mylocation. The application 117 may specify an access configuration through which the server 40 should be reached. For instance, it might specify a data connection of a cellular phone network in which the device 11 is a subscriber. It might alternatively specify an alternative connection, for instance a Wi-Fi connection. The server 40 in these examples is a webserver.

The steps shown in Figure 2 are performed by the first device 11 under control of computer program instructions that constitute the application 117. As such, the application 117 causes the first device 11 to provide the server 40 with information needed for the server to track the first device 11. Advantageously, the software application 117 in the first device 11 is unable to be removed by a user of the first device 11. In this way, the user is unable to control the first device 11 such as to prevent it being tracked by the server 40.

Operation of the server will now be described with reference to Figures 4 and 5.

Starting firstly with Figure 4, operation begins at step Si. At step S2, information is received from devices including the first device 11 and the second device 12. At step S3, received information is stored. The server 40 repeats steps S2 and S3 continually.

Referring now to Figure 5, operation of the server starts at step Si. At step S2, information that is stored is monitored. If it is determined at step S3 that information from a device 11, 12 is overdue, a warning is issued at step S4. Following step S4 or following a negative determination at step S3, the operation returns to step S2, where information is again monitored.

Step S3 of Figure 5 involves determining whether a time of last receiving information from a device 11, 12 exceeds a threshold. The threshold may take any value, for example five minutes. If the threshold is exceeded, it is determined that information is overdue and the warning is issued at step S4. By having the threshold time used by the server 40 approximately equal to an integer multiple of the value of the second timer used by the devices 11, 12, the server 40 can provide the warning at step S4 if the device 11, 12 has not reported having received a BLE advertisement message from a tag 30 for a number of scans that is equal to the integer. In the example of the second timer having a value of 60 seconds and the threshold implemented by the server 40 being five minutes, the server 40 will issue a warning at step S4 if the device 11, 12 has not reported information about a received BLE advertisement message from a tag 30 for five successive scans.

The server 40 stores a database 422 that relates to two different sets of information.

The first set of information relates to device identifiers and tag identifiers received from devices 11, 12. In some implementations, the server 40 stores only recent information relating to a given device 11, 12. For instance, the server 40 may store only the last one, three or five elements of information received from a device 11. In other implementations, the server 40 stores all information received from a given device 11, 12. In these implementations, the server 40 maintains a complete record, from which movement of a device 11, 12 over a given time period can be retrieved at any time. In implementations where only most recent information is stored, only a small number of last known locations may be derived.

The second part of the database 422 stored in the server 40 includes a second set of information relating tag identifiers to the locations associated with the corresponding tags. This database is used by the server 40 to identify locations of devices 11, 12. For instance, storing information in the database 422 identifying that tag number 1234 has a location corresponding to the staff canteen can allow the server 40 to identify that the location of the device 11 is the staff canteen when it receives information identifying tag number 1234 and the identifier of the device 11.

The first set of information is received from the devices 11, 12, whereas the second set of information is not.

The server 40 is configured to provide an operator of the server with information about the locations of tracked devices in a user-friendly way.

For instance, the locations of users can be provided in a table format. Here, a first column includes the names of users associated with devices 11, 12, and a second column includes information identifying a last known location of the user. The user's may be listed in alphabetical order in the first column.

Colour coding may be used to indicate how up-to-date the location information is. For instance, a first colour, e.g. green, may be used in rows where the location information is up-to-date, for instance because information was received from the corresponding device within the last one or two minutes. A second colour, e.g. orange, may be used to identify users where information has not been received very recently. An orange colour might be used, for instance, to denote users where information has not been received for a small number of reporting intervals, for instance as set by the value of the second timer in the devices 11, 12. A third colour, for instance red, can be used to denote users for which information identifying the location of their device has not been received for a higher threshold period of time, for instance five minutes.

By configuring the server 40 in such a way, an operator of the server 40 can easily determine which personnel are within the building that is being monitored and which personnel are external to the building. By placing tags 30 at exit points to the building, a user can be assumed or determined to have exited the building if their last known location was at an exit point some time ago.

The server 40 may restrict access to user location information to operators that have successfully passed a security test, for instance by entering a valid username and password combination.

By the operation of the tags 30, the devices 11, 12 and the server 40 as described above, a tracking system is provided. As briefly mentioned above, this can be provided in its simplest form through provision of some low cost tags 30 at a number of locations, by the provision of a software application on a mobile phone or other portable device equipped with Bluetooth low energy functionality, and a suitably programmed server. Of course, the server 40 may be pre-existing and the system can then be provided through a software application provided on the existing server 40.

A number of use cases are envisaged.

In a first use case, staff can be tracked in a large premises. Each member of staff that is provided with a device 11, 12 can be tracked from the information that those devices upload to the server 40. This can give rise to a number of advantages.

It can help the management of the premises. For instance, it can allow staff to be instructed such that congestion in a particular corridor at a particular time of day is avoided or reduced.

It can also help to ascertain whether the premises have been evacuated in the case of an emergency. Information about whether the premises have been evacuated can be gleaned from interrogating the information stored in the server 40 to determine whether any devices 11, 12 have recently reported a position that is within the building (and the owners of those devices have not been ascertained to be outside of the building), and also by tracking movement of the devices 11, 12 along a route to an exit of the building after an alarm was sounded.

It can also aid the tracking of key staff, such as first aiders and duty managers etc. If a certain member of staff or a member of staff within a particular category is required, the location of the or a suitable staff member may be determined by interrogating the information stored in the server 40.

In a second use case, the locations of elderly people or people with restricted movement within a home can be tracked. In such a use case, the location of a particular user, such as a resident or a patient, can be determined by interrogation of the information stored in the server 40.

The information stored in the server 40 can be used to help provide a better health service. For instance, when the information stored in the server 40 indicates that a resident or a patient has entered a particular room, for instance a kitchen, the user can be reminded to perform a certain action, for instance take some medicine. Reminding can occur from an operator of the server 40 or could be announced automatically.

The information stored in the server 40 can be used to determine a level of activity for a resident or patient. If a determined level of activity is below a threshold, the resident or patient may be provided with a message to be more active. The message may be provided by an operator of the server 40 or may be provided automatically.

In a third use case, the management of distribution of personnel within a large building or complex may be provided. For instance, in a large public place such as a sporting venue, an exhibition centre, theme park etc., better management of personnel such as first aid staff, cleaners, service assistants, duty managers, etc. may be better managed.

Interrogation of the information stored in the server in any of the above situations can involve a user interacting with the server 40 through the key board 421 and the display 419. It will be appreciated that the above-described embodiments are not limiting on the scope of the invention, which is defined by the appended claims and their alternatives. Various alternative implementations will be envisaged by the skilled person, and all such alternatives are intended to be within the scope of the claims. A number of alternatives will now be described.

Instead of the tag identifier and device identifier being uploaded to the server 40 in step S7 of Figure 2, it may be communicated to the server in some other way. For instance, the tag identifier and device identifier may be sent to the server 40 by email, or by instant message (IM), or by SMS.

Instead of successive scans by the device 11 (this relates to step S2 of Figure 2) being periodic, they may alternatively be irregular to some degree. For instance, successive scans may be performed on an approximate periodic basis, although with scanning delayed or brought forwards from a time that would be truly periodic where the BLE module 13 is required for some other purpose or where processing or other resources of the device 11 are needed for some other purpose.

Although it is described in Figure 2 that scanning is performed for a period that is set by the first timer, other variations are within the scope of the inventions. For instance, scanning may be performed at step S2 until a BLE advertisement message having certain properties is received. The properties may be that a quality metric, for instance signal strength or bit error rate, exceeds a threshold. Alternatively, scanning may be enabled for a period of time equal to the shortest of a BLE advertisement signal being received and a timer expiring.

In Figure 2, the tag identifier is decoded from the message that was identified at step S6 as being the strongest received message. Advantageously, the tag identifier is decoded only from the strongest message, and the other received messages are not decoded. Alternatively, all messages can be decoded, although only the tag identifier of the strongest received message is uploaded to the server 40.

Although in the above it is only the tag identifier of the strongest received message that is uploaded to the server 40, alternatively more than one tag identifier received during a scan may be uploaded. For instance, the device 11 may be configured to upload all tag identifiers from messages that were received with a quality metric exceeding a threshold. Alternatively, the device 11 may be configured to upload to the server 40 tag identifiers from the N (e.g. two, three or four) messages that were received with the highest quality metric.

In the above, the radio is disabled at step S8 of Figure 2 after uploading the tag identifier and device identifier at step S7 and the radio remains disabled until step S2 is again performed. This minimises power consumption of the device 11 when

implementing the method of Figure 2. In alternative implementations, the radio resources may not be disabled at step S8 and may be usable by the device, by the application 117 or some other software operating on the device 11, for some other purpose.

Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

A computer-readable medium may comprise a computer-readable storage medium that may be any tangible media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer as defined previously.

According to various embodiments of the previous aspect of the present invention, the computer program according to any of the above aspects, may be implemented in a computer program product comprising a tangible computer-readable medium bearing computer program code embodied therein which can be used with the processor for the implementation of the functions described above. Reference to "computer-readable storage medium", "computer program product", "tangibly embodied computer program" etc, or a "processor" or "processing circuit" etc. should be understood to encompass not only computers having differing architectures such as single/multi processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or configuration settings for a fixed function device, gate array, programmable logic device, etc.

If desired, the different functions discussed herein may be performed in a different order and/or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.