WO2016177932A1

WO2016177932A1 - Positioning arrangement

Info

Publication number: WO2016177932A1
Application number: PCT/FI2015/050304
Authority: WO
Inventors: Teemu Savolainen; Antti Rantaeskola
Original assignee: Nokia Technologies Oy
Priority date: 2015-05-05
Filing date: 2015-05-05
Publication date: 2016-11-10

Abstract

A technique for operating a gateway device (110) is provided. According to an example embodiment, the technique comprises receiving, using a wireless communication apparatus (112), inbound beacon messages from one or more other gateway devices (110), transmitting, using the wireless communication apparatus (112), outbound beacon messages to other gateway devices (110), extracting gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices (110), monitoring movement of the gateway device (110) on basis of the neighborhood information, and transmitting, using the wireless communication apparatus (112), one or more gateway-moved indication messages in response to detecting movement of the gateway device (110).

Description

Positioning arrangement

TECHNICAL FIELD

The example and non-limiting embodiments of the present invention relate to a positioning arrangement and gateway devices employed as part of the positioning arrangement.

BACKGROUND

A positioning system that locates objects of people using radio waves, magnetic fields, acoustic signals or other suitable sensory information is commonly referred to as an indoor positioning system (IPS). However, despite this terminology, an IPS may be equally well deployed outdoors as well.

An IPS solution may rely on one or more locator entities arranged in an area of interest and at least one server entity. Each of the locator entities is positioned in a respective known location within or close to the area of interest. Each of the locator entities extracts location/presence information that is indicative of a position of an object of interest with respect to a predefined reference point and forwards this information (possible in a processed form) to the server entity. The server entity, in turn, derives or at least estimates the location of the object of interest based on the location/presence information pertaining to the object of interest received from one or more locator entities. In a most straightforward scenario, the information extracted and forwarded by a locator entity comprises an indication of presence/absence of the object of interest in vicinity of the locator entity. In a more sophisticated scenario, the extracted/forwarded information includes measurement data or other indications that enable estimating the distance between the object of interest and the location of the locator entity. Alternatively, the locator entity may convert the extracted information into a form that serves as an indication of the distance between the object of interest and the location of the locator entity before forwarding this information to the server entity. Such an IPS solution is, quite naturally, sensitive to a malfunction or an unexpected change of location of any of the locator entities, which is likely to lead to inaccurate or even incorrect location estimation.

SUMMARY According to an example embodiment, a method for operating a gateway device is provided, the method comprising receiving inbound beacon messages from one or more other gateway devices and transmitting outbound beacon messages to other gateway devices using a first wireless communication means, extracting gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices, monitoring movement of the gateway device on basis of the neighborhood information, and transmitting, using the first wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the gateway device. According to another example embodiment, an apparatus is provided, the apparatus comprising a communication portion comprising at least a first wireless communication apparatus for receiving inbound beacon messages one or more other devices and for transmitting outbound beacon messages to other devices and a control portion for operating the apparatus as a gateway device. The control portion is configured to extract gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices, monitor movement of the apparatus on basis of the neighborhood information, and transmit, using the first wireless communication apparatus, one or more gateway-moved indication messages in response to detecting movement of the apparatus.

According to another example embodiment, an apparatus is provided, the apparatus comprising means for receiving inbound beacon messages from one or more other gateway devices, means for transmitting outbound beacon messages to other gateway devices using, means for extracting gateway information on basis of inbound beacon messages, means for obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices, means for monitoring movement of the gateway device on basis of the neighborhood information, and means for transmitting, using the first wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the gateway device.

According to another example embodiment, an apparatus is provided, the apparatus comprising at least one processor, a memory storing a program of instructions, wherein the memory storing the program of instructions is configured to, with the at least one processor, configure the apparatus to operate a gateway device, comprising receiving, using a wireless communication apparatus, inbound beacon messages from one or more other gateway devices and transmitting, using the wireless communication apparatus, outbound beacon messages to other gateway devices, extracting gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices, monitoring movement of the apparatus on basis of the neighborhood information, and transmitting, using the first wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the apparatus. According to another example embodiment, a computer program is provided, the computer program comprising computer readable program code configured to cause performing the following when said program code is run on a computing apparatus: receive, using a wireless communication apparatus, inbound beacon messages from one or more other gateway devices, transmit, using the wireless communication apparatus, outbound beacon messages to other gateway devices, extract gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices, monitor movement of the computing apparatus on basis of the neighborhood information, and transmit, using the wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the computing apparatus. The computer program referred to above may be embodied on a volatile or a nonvolatile computer-readable record medium, for example as a computer program product comprising at least one computer readable non-transitory medium having program code stored thereon, the program which when executed by an apparatus cause the apparatus at least to perform the operations described hereinbefore for the computer program according to an example embodiment of the invention.

The embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" and its derivatives are used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features described hereinafter are mutually freely combinable unless explicitly stated otherwise.

Some features of the invention are set forth in the appended claims. Embodiments of the invention, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of some example embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF FIGURES

The embodiments of the invention are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, where Figure 1 schematically illustrates some components of a positioning arrangement according to an example embodiment;

Figure 2 schematically illustrates some components of an exemplifying computing device according to an example embodiment;

Figure 3 schematically illustrates some components of an exemplifying computing device according to an example embodiment; Figure 4 schematically illustrates some components of an exemplifying computing device according to an example embodiment; and

Figure 5 illustrates a method according to an example embodiment. DESCRIPTION OF SOME EMBODIMENTS Figure 1 schematically illustrates some elements of a positioning arrangement 100 according to an example embodiment. The positioning arrangement 100 as depicted in Figure 1 includes gateway devices 1 10-i and a server device 120. The gateway devices 1 10-i (represented by gateway devices 1 10-1 to 1 10-8 in the example of Figure 1 ) are arranged in desired predetermined positions within or close to an area of interest, in other words within or close to the area where positioning is to take place. For the sake of an example, the gateway devices 0-i are arranged in rooms A to F, which, together with their immediate vicinity, form the area of interest. In particular, in the example of Figure 1 the gateway devices 1 10-1 and 1 10-2 are arranged in room A, the gateway devices 1 10-7 and 1 10-8 are arranged in room F, whereas the gateway devices 1 10-3, 1 10-4, 1 10-5 and 1 10-6 are arranged, respectively, in rooms B, C, D and E. In general, the gateway devices 1 10-i may be distributed across the rooms (and/or other spaces) within the area of interest and within the rooms (and/or within other spaces) in a desired manner. The server device 120 may be located within the area of interest or it may be located outside the area of interest. The positioning arrangement 100 may be employed to derive or estimate the location of tag devices 130-i, represented in the example of Figure 1 by a tag device 130-1 (in room C) and a tag device 130-2 (in room D).

The tag device 130 is arranged to transmit, using a suitable short-range wireless communication technique, messages that carry identification assigned for the respective tag device 130-i, thereby indicating its identity and presence to the gateway devices 1 10-i. Without losing generality, these messages transmitted from the tag device 130 may be referred to as advertising messages due to their nature of 'advertising' the presence of the respective tag device 130-i. An advertising message may carry, in addition to the identification of the transmitting device, further information pertaining to transmitting device and/or information related to services and/or information available at the transmitting device.

The gateway device 1 10-i is arranged to scan for the advertising messages originating from the tag devices 130-i and, in response to receiving an advertising message, to transmit information received in the advertising message and/or information derived on basis of the advertising message to the server device 120 in a tracking message. The gateway device 1 10 may transmit the tracking message to the server device 120 by employing a suitable wireless communication technique. The gateway device 1 10 is further arranged to transmit advertising messages that carry identification assigned for the respective gateway device 1 10-i, thereby indicating its identity and presence to the other gateway devices 1 10. The advertising messages transmitted from the gateway device 1 10 are transmitted using a suitable short-range wireless communication technique, preferably the same one as applied for transmitting the advertising messages from the tag devices 130. Moreover, while scanning for advertising messages originating from the tag devices 130, the gateway device 1 10 may be further arranged to scan for advertising messages originating from the other gateway devices 1 10-i. Yet further, the gateway device 1 10 is further arranged to keep track of the advertising messages received from the other gateway devices 1 10-i, thereby enabling the gateway device 1 10 to establish its position with respect to the other gateway devices 1 10-i on basis of information received in advertising messages from the other gateway devices 1 10-i and/or on basis of information derived on basis of advertising messages from the other gateway devices 1 10-i.

The server device 120 is arranged to receive tracking messages pertaining to a certain tag device 130-i from one or more gateway devices 1 10-i and to derive or estimate the location of the certain tag device 130-i in dependence of information received in the tracking messages on basis of predefined (and known) locations of the gateway devices 1 10. The derived or estimated location may be stored in a database in the server device 120 to enable subsequent tracking of the certain tag device 130-i. Additionally or alternatively, the derived or estimated location of the certain tag device 130-i may be provided for further processing in the server device 120 or in another device. The further processing may result in, for example, displaying an indication of the derived or estimated location via a user interface of the server device 120 or another device and/or invoking an alarm or another suitable action in response to the derived or estimated location indicating a position that is outside a predefined area or a position that is inside a predefined area. As an example in this regard, in the example of Figure 1 an alarm may be invoked in response to the derived or estimated location of one of the tag devices 130 is outside the area of interest formed by the rooms A to F or in response to the derived or estimated location of one of a certain tag device 130 (e.g. the tag device 130-1 ) is inside a predefined part within the area of interest (e.g. in room F). The operation of the positioning arrangement 100 as outlined in the foregoing typically relies on wireless communication on radio frequencies between a pair of gateway devices 1 10 and between a gateway device 1 10-i and a tag device 130-i, thereby making the positioning arrangement 100 useable as an indoor positioning system (IPS). Various examples concerning operation of the positioning arrangement 100 provided in the following, at least implicitly, assume wireless communication over radio frequencies between devices employed to embody the positioning arrangement 100. However, wireless radio communication serves as a non-limiting example in this regard and a different wireless communication technique may be applied instead (or in addition to wireless radio communication) without departing from the scope of the present invention. As a few examples in this regard, the wireless communication between a pair of gateway devices 1 10 and between a gateway device 1 10i and a tag device 130-i may be provided, at least in part, by using acoustic signals, by using optical signals or by making use of magnetic fields.

Typically, each of the gateway devices 1 10 is provided by a respective portable device that is installed in a predefined location within or close to the area of interest in a permanent or fixed manner in order to serve as a component of the positioning arrangement 100. Due to this role in the positioning arrangement 100, a gateway device 1 10-i may be also referred to as a locator device 1 10-i. Herein, the term portable device refers to a device that is small and lightweight enough to be conveniently carried to its desired location or moved to another location. Such a device may be an extremely lightweight and small device, e.g. a specific-purpose device implemented as an 'extension' of an electric plug. Using such purpose-built device to provide the gateway device 1 10 enables power-efficient and low-cost design. As another example, the portable device that is applied to provide the gateway device 1 10 may be a mobile user device such as a mobile phone, a smartphone, a tablet computer, etc. As a further example, the portable device that is applied to provide the gateway device 1 10 may not necessarily be small and lightweight enough to serve as a mobile device constantly carried by a user. Such a portable device may comprise e.g. a general-purpose computer such as a laptop computer or a desktop computer that is arranged to operate as the gateway device 1 10-i (possibly in parallel with providing other functions and/or services). Using any of such portable devices to provide the gateway devices 1 10 enables relatively easy installation and reconfiguration of the positioning arrangement 100. The reference to permanent or fixed installation of the portable device refers to the fact that the gateway device 1 10 is assumed to remain in its predefined location to ensure correct operation of the positioning arrangement 100. However, a downside of the easy installation/reconfiguration enabled by the use of small and lightweight portable devices as the gateway devices is that a gateway device 0-i may be e.g. moved from its predefined location either accidentally or in purpose by a malicious party, which may result in an inaccurate or even incorrect operation of the positioning arrangement 100. Figure 2 schematically illustrates some components of an exemplifying computing device 210 that may be arranged to serve as a gateway device 1 10. The computing device 210 comprises a communication portion 1 12 that comprises a first wireless communication means 1 12a for wireless communication with other devices and a second wireless communication means 1 12b for wireless communication with other devices. The computing device 210 further comprises a processor 1 16, and a memory 1 15 for storing data and computer program code 1 17. The components of the computing device 210 are coupled to each other by a bus 1 19 that enables transfer of data and control information between the components.

The computing device 210 further comprises a power supply means 1 1 1 for providing operating power to other components of the computing device 210. The computing device 210 may further comprise a temporary power source 1 13, which may be arranged to serve as a temporary source of operating power for other components of the computing device 210 in case the power supply from the external power source PWR is discontinued. The power supply means 1 1 1 may be further arranged to convert the received operation power into a suitable format (e.g. in terms of voltage and current) for provision as the operating power for other components of the computing device 210.

Each of the wireless communication means 1 12a, 1 12b may be provided e.g. by a respective wireless communication apparatus or by a respective wireless communication module. Each of the first and second wireless communication means 1 12a, 1 12b may enable, for example, wireless communication with other devices using a respective wireless communication technique or protocol that enables a point-to- point or a point-to-multipoint wireless connection with another device. As a particular example, the first wireless communication means 1 12a may be employ a wireless communication technique that is different from that employed by the second wireless communication means 1 12b. The computing device 210 is hence capable of communicating with other devices that are equipped with a communication means using the same technique/protocol as the one applied by the first wireless communication means 1 12a or the second wireless communication means 1 12b. In other examples the communication portion 1 12 may comprise only one of the first and second wireless communication means 1 12a, 1 12b. In such a scenario the single wireless communication means is arranged to carry out the operations assigned in the following examples either for the first or the second wireless communication means 1 12a, 1 12b.

In further examples, the communication portion 1 12 may comprise a wired communication means (not shown in Figure 2), which may be provided e.g. by a respective wired communication apparatus or by a respective wired communication module. The wired communication means may be provided in addition to the first and second wireless communication means 1 12a, 1 12b or instead of the second wireless communication means 1 12b. The wired communication means may employ, for example, a power line communications (PLC) technique known in the art or it may provide an Ethernet interface according to IEEE 802.3 standards, where the acronym IEEE stands for the Institute of Electrical and Electronics Engineers.

The computing device 210 may further comprise user I/O (input/output) components that may be arranged, possibly together with the processor 1 16 and a portion of the computer program code 1 17, to provide a user interface for receiving input from a user of the computing device 210 and/or providing output to the user of the computing device 210. The user I/O components may comprise e.g.one or more of the following: a display or a touchscreen for displaying information to a user, a keyboard, a set of one or more keys or control buttons, a touchscreen or a touchpad for receiving input from a user. The computing device 210 may comprise also other further components or portions in addition to those depicted in Figure 2, whereas the ones depicted therein are ones that may be relevant for description of some embodiments of the present invention.

The processor 1 16 may be arranged to provide control means 1 14 for operating the computing device 210 as the gateway device 1 10 in accordance with a portion of the computer program code 1 17 stored in the memory 1 15 and possibly further in accordance with the user input received via the user I/O components and/or in accordance with information received via the wireless communication means 1 12a, 1 12b. The control means 1 14 may include a control function or control portion for controlling operation of the first and second wireless communication means 1 12a, 1 12b, possibly together with a control portion or a control function that may be provided within the respective wireless communication means 1 12a, 1 12b (which will be described later in this text). Although the control means 1 14 is described herein with references to the processor 1 16, the memory 1 15 and the computer program code 1 17 stored therein, this serves as a non-limiting example and in general the control means 1 14 may be provided by hardware means, by software means or by any suitable combination of hardware means and software means.

The server device 120 may be provided by a computing device that is connectable to the gateway devices 1 10 via a computer network. As an example, the server device 120 may be provided by any general-purpose computer such as a laptop computer or a desktop computer that is connectable via the computer network to the gateway devices 1 10 and that is arranged to operate as the server device 120 in context of the positioning arrangement 100.

Figure 3 schematically illustrates some components of an exemplifying computing device 220 that may be arranged to serve as a server device 120. The computing device 220 comprises a communication portion 122 for connecting the server device 120 to the gateway devices 1 10. The communication portion 122 may comprise a wireless communication means for wireless communication with other devices and/or a wired communication means for wired communication with other devices. In case the communication portion 122 comprises a wireless communication means, it preferably employs the same (or otherwise compatible) wireless communication technique as employed by the second wireless communication means 1 12b of the computing device 210 serving as a gateway device 1 10, thereby possibly enabling direct wireless connection between the server device 120 and the gateway device 1 10. The computing device 220 further comprises a processor 126, and a memory 125 for storing data and computer program code 127. The components of the computing device 220 are coupled to each other by a bus 129 that enables transfer of data and control information between the components.

The computing device 220 may further comprise user I/O (input/output) components 128 that may be arranged, possibly together with the processor 126 and a portion of the computer program code 127, to provide a user interface for receiving input from a user of the computing device 220 and/or providing output to the user of the computing device 220. The user I/O components 128 may comprise e.g.one or more of the following: a display or a touchscreen for displaying information to a user, a keyboard, a set of one or more keys or control buttons, a touchscreen or a touchpad for receiving input from a user. As another example, the user I/O components 128 may be arranged to enable control of the computing device 220 via another computing device, e.g. via a control interface that enables receiving input from another computing device and providing output to the other computing device. In such a scenario, the control of the computing device 220 may be provided e.g. by an automated process (e.g. a software) running in the other computing device and/or on basis of user input received and output provided via user interface of the other computing device (e.g. via a webpage). The computing device 220 may comprise also other further components or portions in addition to those depicted in Figure 3, whereas the ones depicted therein are ones that may be relevant for description of some embodiments of the present invention. The processor 126 may be arranged to provide control means 124 for operating the computing device 220 as the server device 120 of the positioning arrangement 100 in accordance with a portion of the computer program code 127 stored in the memory 125 and possibly further in accordance with the user input received via the user I/O components 128 and/or in accordance with information received via the communication portion 122. The control means 124 may include a control function or control portion for controlling operation of the communication means provided in the communication portion 122, possibly together with a control portion or a control function that may be provided within the respective communication means of the communication portion 122. Although the control means 124 is described herein with references to the processor 126, the memory 125 and the computer program code 127 stored therein, this serves as a non-limiting example and in general the control means 1 14 may be provided by hardware means, by software means or by any suitable combination of hardware means and software means.

Although depicted herein as a single entity and described in the examples provided in the foregoing and in the following with references to a single server device 120, the functions described for the server device 120 may be jointly provided by one or more computing devices 220. In such an arrangement the one or more computing devices 220 may be arranged to provide a cloud computing arrangement that is configured to provide the functions described for the server device 120. Each of the tag devices 130 may be provided as a mobile device. As described in the foregoing, the tag device 130 is arranged to transmit advertising messages to indicate its identity and presence to the gateway devices 1 10. Due to this role in the positioning arrangement 100, a tag device 130-i may be also referred to as a tracked device 130- I As an example, a tag device 130-i may be provided by a specific-purpose device that may be attached to an object of interest. With such tag device(s) 130 the positioning arrangement 100 may be embodied e.g. as an anti-theft arrangement, where the server device 120 is arranged to invoke an alarm (or other action) in response to one of such tag devices 130 exiting the area of interest or exiting a predefined sub-area within the area of interest. As another example, any portable user device, such as a mobile phone, a smartphone, a music player, a media player, a tablet computer, a laptop computer, a portable navigation device, may be arranged to serve as a tag device 130-i in context of the positioning arrangement 100. Such tag device(s) 130 enable using the positioning arrangement 100 to track users of interest and e.g. to invoke an alarm (or other action) in response to one of tracked tag devices 130 exiting or entering the area of interest or a predefined sub-area within the area of interest.

Figure 4 schematically illustrates some components of an exemplifying computing device 230 that may be arranged to serve as a tag device 130-i. The computing device 230 comprises a wireless communication means 132 for wireless communication with other devices, a processor 136, and a memory 135 for storing data and computer program code 137. The components of the computing device 230 are coupled to each other by a bus 139 that enables transfer of data and control information between the components. The computing device 230 may comprise further components or portions in addition to those depicted in Figure 4, whereas the ones depicted therein are ones that may be relevant for description of some embodiments of the present invention. The wireless communication means 132 may be provided e.g. by a respective wireless communication apparatus or by a respective wireless communication module. The wireless communication means 132 may enable, for example, wireless communication with other devices using a respective wireless communication technique or protocol that enables a point-to-point or a point-to-multipoint wireless connection with another device. As a particular example, the first wireless communication means 132 may employ a wireless communication technique that is the same or otherwise compatible with the one employed by the first wireless communication means 1 12a of the gateway devices 1 10. The computing device 230 is hence capable of communicating with other devices that are equipped with a communication means using the same technique/protocol as the one applied by the wireless communication means 132. The computing device 230 may further comprise user I/O (input/output) components that may be arranged, possibly together with the processor 136 and a portion of the computer program code 137, to provide a user interface for receiving input from a user of the computing device 230 and/or providing output to the user of the computing device 230. The user I/O components may comprise e.g. one or more of the following: a display or a touchscreen for displaying information to a user, a keyboard, a set of one or more keys or control buttons, a touchscreen or a touchpad for receiving input from a user. Typically, though, if the tag device 130-i is provided as a specific-purpose device for attachment to an object of interest (e.g. to serve as an anti-theft tag), the computing device 230 may be provided without the user I/O components but input that controls functions of the computing device 230 that are necessary to provide its function as the tag device 130 may be provided upon construction, installation or reconfiguration of the computing device 230.

The processor 136 may be arranged to provide control means 134 for operating the computing device 230 as the tag device 130 in accordance with the computer program code 137 stored in the memory 135 and possibly further in accordance with the user input received via the user I/O components 138 and/or in accordance with information received via the wireless communication means 132. The control means 134 may include a control function or control portion for controlling operation of the wireless communication means 132, possibly together with a control portion or a control function that may be provided within the wireless communication means 132 (which will be described later in this text). Although the control means 134 is described herein with references to the processor 136, the memory 135 and the computer program code 137 stored therein, this serves as a non-limiting example and in general the control means 134 may be provided by hardware means, by software means or by any suitable combination of hardware means and software means.

Any of the wireless communication means 1 12a, 1 12b, 132 referred to in the foregoing may be provided as respective wireless communication apparatus, implemented e.g. as a respective chipset and/or as a respective wireless communication module. For clarity and brevity of description, each wireless communication means 1 12a, 1 12b, 132 may be considered as a single logical entity that may also be capable of processing at least some of the information received via a wireless link and/or at least some of the information that is to be transmitted via the wireless link without external control from other components of the respective device 210, 230 (e.g. from the processor 1 16, 136, respectively). In an example embodiment, the wireless communication means 1 12a, 1 12b, 132 comprises e.g. a wireless transceiver portion for wireless communication and a control portion (or a control function) for controlling operation of the respective wireless transceiver portion and for processing information received/transmitted via the respective wireless transceiver portion. Such a control function may be provided by hardware means, by software means or by a combination of hardware means and software means. As an example in this regard, the wireless communication means 1 12a, 1 12b, 132 may comprise a memory and a processor, and a computer program code stored in the memory may be arranged to, with the processor, provide the control function for controlling operation of the respective wireless communication means 1 12a, 1 12b, 132 either independently or jointly with the control function provided by the memory 1 15, 135, the computer program 1 17, 137 and the processor 1 16, 136 of the respective computing device 210, 230.

A wireless link between the first wireless communication means 1 12a (in the computing device 210 arranged to operate as a gateway device 1 10) and the wireless communication means 132 (in the computing device 230 arranged to operate as a tag device 130) may be provided by employing a suitable short-range wireless communication technique or protocol. The term short-range wireless communication as used herein refers to a wireless communication technique or protocol that enables typical operating range in the scale of tens of meters, e.g. up to 100 meters. However, especially in an indoor environment, the operating range of such short-range wireless communication technique/protocol may be significantly shorter e.g. due to walls and other stationary structures as well as furniture etc. that are likely to partially block or interfere with the radio communication between wireless communication portions. On the other hand, in favorable conditions in outdoor use the operating range may extend to several hundreds of meters. An example of such a wireless technique/protocol is the Bluetooth Low Energy (BLE) protocol, specified e.g. in the Bluetooth Specification Version 4.1 , Covered Core Package version 4.1 (publication date 3 December 2013), incorporated herein by reference in its entirety. In the following, this document is referred to as a Bluetooth Specification. In case the BLE technology is applied, the advertising messages described in the foregoing and in the following may comprise BLE advertising messages. Another example is the Wireless Local Area Network (WLAN) technology, specified e.g. in IEEE 802.1 1 specifications, where the acronym IEEE stands for the Institute of Electrical and Electronics Engineers. However, the BLE and WLAN technologies serve as illustrative and non-limiting examples in this regard, and the description generalizes into any wireless (radio or other) communication technique/protocol that enables transmission of messages that may serve as advertising messages over a wireless link.

A wireless link between the gateway device 1 10 and the server device 120 may be provided via the wireless communication means 1 12b (in the computing device 210 arranged to operate as the gateway device 1 10). The wireless communication technique/protocol applied by the second wireless communication means 1 12b of the computing device 210 typically enables communication over ranges longer than those enabled by the first wireless communication means 1 12a, thereby providing some freedom for locating the server device 120 further away from immediate vicinity of the gateway devices 1 10, hence enabling a single server device 120 to receive and process information received from a plurality of gateway devices 1 10 (possibly from all gateway devices) of the positioning arrangement 100.

Depending on the applied wireless technology/protocol, the computing device 210 may use the second wireless communication means 1 12b to connect a wireless access network available in its vicinity in order to connect to the server device 120 via the computer network. In this regard, for example the WLAN technology or any suitable cellular technology known in the art may be employed to provide the computing device 210 with access to the network and hence with connection to the server device 120. In either of these exemplifying ways to provide the second wireless communication means 1 12b the advertising messages described in the foregoing and in the following may comprise payloads formatted in accordance with an appropriate proprietary protocol, encapsulated e.g. in UDP/IP packets. With these exemplifying wireless communication technologies/protocols the computing device 210 may use the second wireless communication means 1 12b to connect to an access point of a WLAN network or to a base station of a cellular network.

In case the computing device 210 is provided with the temporary power source 1 13, the power supply means 1 1 1 is arranged to selectively draw the operating power either from an external power source PWR or from the temporary power source 1 13. In this regard, under normal operating conditions, the power supply means 1 1 1 may be arranged to draw the operating power for other components of the computing device 210 from the external power source PWR, whereas the power supply means 1 1 1 may be arranged switch to draw the operating power from the temporary power source 1 13 when the power supply from the external power source PWR is discontinued. In case the computing device 210 is provided without the temporary power source 1 13, the power supply means 1 1 1 is arranged to draw the operating power from the external power source PWR. In the following, the mode of operation of the gateway device 1 10 when in receipt of the operating power from the external power source PWR is referred to as a normal mode, whereas, in contrast, the mode of operation of the gateway device when not in receipt of the operating power from the external power source PWR is referred to as a low-power mode. The external power source PWR may be, for example, mains power (e.g. an alternating current (AC) electric power supply that provides an average of 230 V at 50 Hz) or another reliable source of operating power that is arranged to supply an input voltage of predefined characteristics.

The temporary power source 1 13 may comprise, for example, a rechargeable battery, a capacitor or a supercapacitor for storing electrical energy that may serve as temporary operating power in case of discontinuation of the power supply from the external power source PWR. Regardless of the applied way to embody the temporary power source 1 13, during the normal mode the temporary power source 1 13 is continuously charged with electrical energy received from the external power source PWR (via the power supply means 1 1 1 ). The temporary power source 1 13 is preferably dimensioned such that, when fully charged, it is able to provide at least a certain predefined time period of additional operation time after discontinuation of the power supply from the external power source PWR. Suitable time period may be selected according to the requirement of the underlying positioning arrangement 100, whereas the capacity of the (electrical) components of the temporary power source 1 13 required to provide the desired time period of additional operating time depends on e.g. the power consumption of the gateway device 1 10. The time period may be basically anything between a few tens of seconds up to several hours. A tag device 130-i may be arranged to periodically transmit (e.g. broadcast) advertising messages over a wireless link to other devices. In this regard, the control means 134 in the tag device 130-i may be arranged to cause the wireless communication means 132 to periodically transmit one or more advertising messages. As described in the foregoing, an advertising message carries at least an identification of the device transmitting the advertising message, possibly together with other information pertaining to the transmitting device. Thus, the advertising messages transmitted from the tag device 130-i carry at least a tag identifier to indicate identity assigned for the tag device 130-i and hence serve as an indication of presence and identification of the tag device 130-i to other devices that are within operating range of the first wireless communication means 132. The identity assigned for the tag device 130-i may be e.g. an address assigned to the wireless communication means 132 or other address assigned for the tag device 130-i. An advertising messages originating from the tag device 130-i may further carry a status indication or an indication of other kind that identifies the advertising message as a message that is associated with tracking of the tag device 130-i in context of operation of the positioning arrangement 100. As an example, the transmission of advertising messages may be carried out according to a predefined schedule. The predefined schedule may define, for example, that a set of one or more advertising messages is transmitted at predefined time intervals. As another example, the transmission of a set of one or more advertising messages may be carried out in response to receiving one or more scan request messages from one of the gateway devices 1 10. A gateway device 1 10-i may be arranged to receive the advertising messages originating from the tag devices 130. In order to receive advertising messages originating from any of the tag devices 130 that may be within operating range, the control means 1 14 in the gateway device 1 10-i may be arranged to cause the first wireless communication means 1 12a to scan for advertising messages originating from the tag devices 130. The scanning may comprise passive scanning or active scanning. Passive scanning may comprise just listening to one or more predefined channels for possible advertising messages from the tag devices 130, whereas the active scanning may comprise transmitting one or more scan request messages over one or more (first) predefined channels and listening to one or more (second) predefined channels for possible advertising messages sent from the tag devices 130 in response to the scan request messages.

The control means 1 14 in the gateway device 1 10-i may be arranged to extract, in response to reception of an advertising message from a tag device 130-i, one or more pieces of information on basis of the received advertising message. This information, referred to as tracking information, may comprise one or more pieces of information carried in the advertising message and/or one or more pieces of information extracted on basis of a signal carrying the received advertising message. The tracking information may be stored in the memory 1 15 for subsequent use by the gateway device 1 10-i and/or at least part of the tracking information and/or information derived therefrom may be transmitted to the server device 120 to facilitate estimation of the position of the tag device 130-i therein. As an example, the control function 1 14 in the gateway device 1 10-i may be arranged to extract the tag identifier from an advertising message received from a tag device 130-i and store the extracted tag identifier as (part of) the tracking information pertaining this particular tag device 130 in the memory 1 15. As another example, the control function 1 14 in the gateway device 1 10-i may be arranged compute a received signal strength indication (RSSI) on basis of a received signal that carried the received advertising message and complement the respective tracking information in the memory with the computed RSSI. Optionally, the tracking information may be further complemented with an indication of the reception time of the advertising message. Yet further, in case the transceiver portion in the first wireless communication means 1 12a is equipped with a directional antenna, the tracking information may be further complemented with an indication of direction of arrival of the advertising message (which may be obtainable from the wireless communication means 1 12).

A gateway device 1 10-i may be arranged to transmit, in response to one or more advertising messages received from a tag device 130, one or more messages to the server device 120. In this regard, the control means 1 14 in the gateway device 1 10-i may be further arranged to cause the second wireless communication means 1 12b to transmit, in response to reception of an advertising message from the tag device 130- i, a tracking message to the server device 120 to facilitate estimation of the position of the tag device 130-i in the server device 120. The tracking message comprises at least a GW identifier to indicate the identity assigned for the gateway device 1 10-i, the tag identifier as an indication of the identity assigned for the tag device 130-i and a distance indication that is descriptive of a distance between the gateway device 1 10-i and the tag device 130-i. The distance indication may comprise the extracted RSSI as such or another distance measure derived on basis of the extracted RSSI. The tracking message may further comprise other pieces of information included in the tag information, e.g. direction information such as the indication of the direction of arrival of the advertising message referred to in the foregoing. The identity assigned for the gateway device 1 10-i may be e.g. an address assigned to the first wireless communication means 1 12a or other address assigned for the gateway device 130-i.

The server device 120 may be arranged to receive tracking messages from a plurality of gateway devices 1 10-i, each of which is assumed to occupy a predefined location within or close to the area of interest and which predefined location is known by the server device 120. Consequently, the server device 120 is able to derive or estimate the location of a tag device 130-i on basis of the known locations of the gateway devices 1 10-i and information pertaining to the tag device 130-i received in tracking messages originating from one or more gateway devices 1 10. In this regard, the server device 120 may be arranged to, in response to receiving tracking messages pertaining to the tag device 130-i from one or more gateway devices 1 10, to estimate the location of the tag device 130-i at least in part on basis of the information received in the tracking messages. In particular, while the server device 120 is able to identify the gateway device(s) 1 10 on basis of the GW identifier(s) received in the respective tracking message(s) and identify received tracking message(s) as one(s) pertaining to the tag device 130-i on basis of the tag identifier(s) received in the respective tracking message(s), the server device 120 may use the distance indication(s) and possible further information (e.g. direction of arrival information) received in the respective tracking message(s) in derivation or estimation of the position of the tag device 130-i. In this regard, any location estimation technique based on such pieces of information known in the art may be applied.

When operating in the normal mode, the control function 1 14 in the gateway device 1 10-i may be arranged to cause the first wireless communication means 1 12a to periodically transmit (e.g. broadcast) advertising messages. As described in the foregoing, an advertising message carries at least an identification of the device transmitting the advertising message, possibly together with other information pertaining to the transmitting device. Thus, the advertising messages transmitted from the gateway device 1 10-i carry at least the GW identifier assigned for the gateway device 1 10-i to indicate presence and identity of the gateway device 1 10-i to other devices that are within operating range of the first wireless communication means 1 12. In other words, these advertising messages serve as beacon messages regarding the presence (and position) of the gateway device 1 10-i. The beacon messages transmitted from the gateway device 1 10-i may further carry a status indication or an indication of other kind that identifies the message as a beacon message. As an example, the transmission of beacon messages may be carried out according to a predefined schedule, which may define, for example, that a set of one or more beacon messages is transmitted at predefined time intervals. The beacon messages transmitted from the gateway device 1 10-i may be referred to as outbound beacon messages.

Due to this operation of the gateway devices 1 10 in the normal mode, the gateway device 1 10-i may be able to receive advertising messages serving as beacon messages originating from the other gateway devices 1 10 that are within operating range of the first wireless communication means 1 12a. In order to enable reception of the beacon messages, the control means 1 14 may be arranged to cause the first wireless communication means 1 12a in the gateway device 1 10-i to scan for beacon messages from other gateway devices 1 10. This scanning may be carried out jointly with the scanning carried out in order to detect/receive the advertising messages from the tag devices 130. The scanning may comprise passive scanning or active scanning. Passive scanning may comprise just listening to one or more predefined channels for possible beacon messages from the other gateway devices 1 10, whereas the active scanning may comprise transmitting one or more scanning request messages over one or more (first) predefined channels and listening to one or more (second) predefined channels for possible beacon messages sent from one or more other gateway devices 1 10 in response to the scanning request messages. The beacon messages received at the gateway device 1 10-i from the other gateway devices 1 10 may be referred to as inbound beacon messages.

The control means 1 14 in the gateway device 1 10-i may be arranged to extract, in response to reception of a beacon message from another gateway device 1 10, one or more pieces of information on basis of the received inbound beacon message. This information, referred to as gateway information (GW information, in short), may comprise one or more pieces of information carried in the received beacon message and/or one or more pieces of information extracted on basis of a signal carrying the received beacon message. The GW information may be stored in the memory 1 15 for subsequent use by the gateway device 1 10-i and/or at least part of the GW information and/or information derived therefrom may be transmitted to the server device 120. As an example, the control means 1 14 may be arranged to extract the GW identifier from a received beacon message received from another gateway device 1 10 and store the extracted GW identifier as (part of) the GW information in the memory 1 15 for subsequent use. As another example, the control means 1 14 may be arranged compute a received signal strength indication (RSSI) on basis of a received signal that carried the received beacon message and complement the respective GW information in the memory 1 15 with the computed RSSI. Optionally, the GW information may be further complemented with an indication of the reception time of the beacon message. Moreover, in case the transceiver portion in the first wireless communication means 1 12a is equipped with a directional antenna, the GW information may be further complemented with an indication of direction of arrival of the beacon message (which may be obtainable from the first wireless communication means 1 12a).

Since the gateway device 1 10-i is caused to store the GW information discussed in the foregoing for inbound beacon messages it receives from the other gateway devices 1 10, the gateway device 1 10-i effectively maintains information that defines its neighborhood in the positioning arrangement 100 with respect to the other gateway devices 1 10 and hence one or more sets of the GW information stored in the gateway device 1 10-i (e.g. in the memory 1 15) may be referred to as neighborhood information for the gateway device 1 10-i. Examples of obtaining the neighborhood information on basis of the GW information extracted from inbound beacon messages received from one or more other gateway devices 1 10 will be described in the following. Any significant change in this neighborhood information likely serves as an indication that either the gateway device 1 10-i itself or one or more of the other gateway devices 1 10 in its neighborhood are either malfunctioning or have been relocated. The control means 1 14 in the gateway device 1 10-i may be further arranged to cause the second wireless communication means 1 12b to transmit GW information messages to the server device 120 to facilitate monitoring the operation of the positioning arrangement 100 in the server device 120. A GW information message comprises at least the GW identifier of the gateway device 1 10-i transmitting the beacon information message, GW identifiers of one or more the gateway devices 1 10 to which the GW information included in the GW information message pertains, and GW information pertaining to one or more other gateway devices 1 10. As an example, a GW information message concerning a certain other gateway device 1 10-j may be transmitted from the gateway device 1 10-i in response to the gateway device 1 10-i receiving an inbound beacon message from the gateway device 1 10-j. Such GW information message may carry at least part of the GW information extracted from and/or on basis of the inbound beacon message that triggered the transmission of the GW information message. As another example, the control means 1 14 in the gateway device 1 10-i may be arranged to periodically cause transmission of a GW information message that includes GW information pertaining to one or more other gateway devices 1 10, e.g. all other gateway devices 1 10 in the neighborhood of the gateway device 1 10-i. Periodic transmission may involve transmitting GW information messages at predefined intervals. Such periodically-transmitted GW information message may carry, for example, at least part of the GW information extracted from and/or on basis of the most recently received inbound beacon message from each other gateway device 1 10 in the neighborhood of the gateway device 1 10-i. As another example, such GW information message may carry at least part of the GW information extracted from and/or on basis of any received inbound beacon message from any of the other gateway devices 1 10 in the neighborhood of the gateway device 1 10-i during a predefined time period (e.g. a time period of a predefined duration that immediately precedes transmission of the respective GW information message).

In a scenario where the computing device 210 is provided with the temporary power source 1 13, in case the gateway device 1 10-i detects a discontinuation of the operating power supply from the external power source PWR, it automatically switches to draw operating power from the temporary power source 1 13 instead of the external power source PWR. A change to draw the operating from the temporary power source 1 13 results in the control means 1 14 switching the operational mode of the gateway device 1 10-i from the normal mode to the low-power mode.

As an example, this may involve the power supply means 1 1 1 detecting discontinuation of the operating power supply from the external power source and automatically switching to draw the operating power from the temporary power source 1 13 instead without involvement of other component. In this regard, the power supply means 1 1 1 may be arranged to indicate this change to the control means 1 14, which may, consequently, implement a mode change from the normal mode to the low-power mode. In a scenario where the computing device 210 is provided without the temporary power source 1 13, discontinuation of the operating power supply from the external power source PWR results in immediate or substantially immediate shutdown of the gateway device 1 10-i without resorting to operation in the low-power mode. When operating in the low-power mode, the control means 1 14 in a gateway device 1 10-i may be arranged cause transmission of one or more loss of power indication messages from the gateway device 1 10-i. Hence, the control means 1 14 in the gateway device 1 10-i may be arranged to initiate transmission of one or more loss-of- power indication messages in response to switching from the normal mode to the low- power mode (or directly in response to switching to draw the operating power from the temporary power source 1 13). The loss-of-power indication message includes at least the GW identifier to identify the source of the loss-of-power indication message.

According to an example embodiment, the control means 1 14 in the gateway device 1 10-i may be configured to cause the first wireless communication means 1 12a to transmit the loss-of-power indication messages. A loss-of-power indication message may be transmitted e.g. as an advertising message that, in addition to the GW identifier, carries at least a status indication or an indication of other kind that identifies the message as the loss-of-power indication message. As an example, the transmission of loss-of-power indication messages may be carried out according to a predefined schedule, which may define, for example, that a set of one or more loss-of- power indication messages is transmitted at predefined time intervals when the gateway device 1 10-i is operating in the low-power mode.

Due to this operation of the gateway devices 100 in the low-power mode, the gateway device 1 10-i may receive loss-of-power indication messages from the other gateway devices 1 10. Consequently, the control means 1 14 in the gateway device 1 10-i may be arranged to inform, in response to receiving a loss-of-power indication message from another gateway device 100-j, the server device 120 about the loss of power in the gateway device 1 10-j identified in the received loss-of-power indication message. This may involve the gateway device 1 10-i transmitting a message in this regard to the server device 120 by using the second wireless communication means 1 12b, e.g. by forwarding the information received in the loss-of-power indication message via the second wireless communication means 1 12b, complemented with the GW identifier of the gateway device 1 10-i that is forwarding the information received in the loss-of- power indication message. Upon reception of such message the server device 120 is able to invoke necessary action(s) due to loss of power in the indicated gateway device 1 10-j, including e.g. invocation of an alarm via a user interface of the server device 120 or via an user interface of another device that is coupled or connected to the server device 120.

According to another example embodiment, the control means 1 14 in the gateway device 1 10-i may be arranged to cause, instead of or in addition to transmitting the loss-of-power indication messages via the first wireless communication means 1 12a, the second wireless transmission means 1 12b to transmit the loss-of-power indication messages to the server device 120. In this scenario, a loss-of-power indication message may be provided as any message that, in addition to the GW identifier, carries at least a status indication or an indication of other kind that identifies the message as the loss-of-power indication message. Upon reception of such message the server device 120 is able to invoke necessary action(s) due to loss of power in the gateway device 1 10-i, including e.g. invocation of an alarm via a user interface of the server device 120 or via an user interface of another device that is coupled or connected to the server device 120.

According to an example embodiment, the control means 1 14 in the gateway device 1 10-i may be arranged to discontinue, in response to switching from the normal mode to the low-power mode (or directly in response to switching to draw the operating power from the temporary power source 1 13), transmission the outbound beacon messages in order to save the operating power available in the temporary power source 1 13. Additionally or alternatively, the control means 1 14 in the gateway device 1 10-i may be arranged to carry out one or more of the following in response to switching from the normal mode to the low-power mode (or directly in response to switching to draw the operating power from the temporary power source 1 13) in order to enable further power savings:

- discontinue the scanning of advertising messages from the tag devices 130 or switch to use a longer scanning interval;

- discontinue the scanning for inbound beacon messages from other gateway devices 1 10 or switch to use a longer scanning interval;

- discontinue transmission of the tracking messages to the server device 120 or switch to use a longer transmission interval; - discontinue transmission of the GW information messages to the server device 120 or switch to use a longer transmission interval; and

- completely turn off the second wireless communication means 1 12b.

The control means 1 14 in a gateway device 1 10-i may be arranged to monitor possible movement of the gateway device 1 10-i on basis of the neighborhood information. The movement monitoring may be carried out during operation in the normal mode, during operation in the low-power or during operation in either of these modes.

The movement monitoring may be based on first neighborhood information and second neighborhood information, where the first neighborhood information is obtained on basis of GW information extracted on basis of inbound beacon messages received from one or more other gateway devices 1 10 during a first time period and where the second neighborhood information is obtained on basis of GW information extracted on basis of inbound beacon messages received from one or more other gateway devices 1 10 during a second time period, wherein the second time period follows the first time period. Each of the first and second time periods may be a period of respective predefined duration. Preferably, the first and second time periods have the same or substantially the same duration. The control means 1 14 in the gateway device 100-i may further compare the first neighborhood information to the second neighborhood information and may detect or indicate movement of the gateway device 1 10-i in response to this comparison indicating a substantial difference. The comparison is carried out in response, e.g. immediately or shortly after, completion of the second time period.

Typically, at least the first time period is a time period during normal mode operation of the gateway device 1 10-1, whereas the second time period may be a time period during the normal mode operation or low-power mode operation. According to an example embodiment, each of the first and second time periods comprise respective time periods during the normal-mode operation such that both the first and second time periods occur during a continuous period of operating the gateway device 1 10-i in the normal mode. According to another example embodiment, the first time period comprises a time period during the normal-mode (i.e. before a switch to the low-power mode) and the second time period comprises a time period during low-power mode. In a further example embodiment the first time period comprises a time period during the normal-mode (i.e. before a switch to the low-power mode or before completely switching off) and the second time period comprises a time period during a subsequent period of the gateway device 1 10-i operating in the normal mode after a period of operation in the low-power mode. In a yet further example embodiment, each of the first and second time periods comprises a respective time period during a period of operation in the low-power mode.

The control means 1 14 in the gateway device 1 10-i may be arranged to periodically obtain the first gateway information, in other words the first time period may occur periodically. As an example, the first gateway information may be obtained at predefined time intervals or according to another predefined schedule. The first neighborhood information may be obtained by taking one or more pieces of GW information extracted on basis of the inbound beacon messages received from other gateway devices 1 10-i (as described in the foregoing) during the respective first time period. The pieces of information taken from the GW information include at least the GW identifier and it may further include e.g. the RSSI computed for the respective received beacon message, reception time of the respective beacon message and/or direction of arrival of the respective beacon message. The control means 1 14 in a gateway device 1 10-i may be arranged to monitor possible movement of the gateway device 1 10-i during operation in the normal mode, after having switched to operate in the low-power mode and/or after having switched to operate in the normal mode after a period of operation in the low-power mode (e.g. after regaining power supply from the external power source PWR). Furthermore, the control means 1 14 in the gateway device 1 10-i may be arranged to initiate, in response to detecting movement of the gateway device 1 10-i, transmission of one or more gateway-moved indication messages to inform one or more other elements of the positioning arrangement 100 regarding the detected movement. Moreover, the control means 1 14 in the gateway device 1 10-i may be arranged to, in response to detecting movement of the gateway device 1 10-i, cause discontinuing transmission of outbound beacon messages and/or transmission of tracking messages from the gateway device 100-i in order to avoid erroneous position estimation in the server device 120 due to assumed change in location of the gateway device 1 10-i.

The movement monitoring and the actions invoked in response to detected movement of a gateway device 1 10-i may be applied to account for the fact that disconnecting the gateway device 1 10-i from the external power source PWR (e.g. unplugging the gateway device 1 10-i from the socket) may be followed by relocation of the gateway device 1 10-i, which in turn may lead to inaccurate or even incorrect location estimation in the server device 120 that assumes the gateway devices 1 10 of the positioning arrangement to occupy fixed or substantially fixed predefined locations. Non-limiting examples of implementing the movement monitoring are described in the following.

According to an example embodiment, the control means 1 14 in the gateway device 1 10-i may be arranged to monitor its movement after a power-up (in the normal mode) following a shut-down after a period of operation in the low-power mode. In order to facilitate the movement monitoring after a power-up, the control means 1 14 in the gateway device 1 10-i may be arranged to store, in response to switching from the normal mode to the low-power mode (or directly in response to switching to draw the operating power from the temporary power source 1 13), the most recently obtained first neighborhood information into a memory portion that provides a persistent (e.g. non-volatile) storage, whose content is hence accessible also after possible shutdown of the gateway device 1 10-i. Such memory portion may be a persistent portion of the memory 1 15 or a portion of persistent memory (e.g. non-volatile memory) provided in a mass storage device accessible by the gateway device 1 10-i. The first neighborhood information so stored may be referred to as backup neighborhood information. As another example, the control means 1 14 in the gateway device 1 10-i may be arranged to obtain, in response to switching from the normal mode to the low-power mode (or directly in response to switching to draw the operating power from the temporary power source 1 13) the first neighborhood information on basis of the GW information extracted on basis of any inbound beacon message received within a time period of predefined duration immediately preceding the switch to the low-power mode (which time period hence serves as the first time period) and store this information as the backup neighborhood information . Due to storage in a non-volatile memory portion, the backup neighborhood information will be available upon a power-up of the gateway device 1 10-i (in the normal mode) following a shut-down after a period of operation in the low-power mode.

Storing the backup neighborhood information in response to switching to operate the gateway device 1 10-i in the low-power mode ensures that the backup neighborhood information reflects up-to-date status of the neighborhood of the gateway device 1 10-i within the positioning arrangement 100. Additionally or alternatively, the control means 1 14 may be arranged to cause storing the backup neighborhood information during the normal mode, thereby ensuring availability of the backup neighborhood information also in case of a sudden loss of all operating power and/or in case the movement monitoring is to be carried out also during the normal mode operation of the gateway device 1 10-i. Such storing of backup neighborhood information may be carried out periodically, e.g. at predefined time intervals or by applying another predefined schedule, and the backup neighborhood information so stored may include the most recently obtained first neighborhood information.

GW device verifying backup neighborhood information (after low-power mode operation)

According to an example embodiment, when the gateway device 1 10-i is again operating in the normal mode (i.e. when again in receipt of operating power from an external power source) after a period of operation in the low-power mode, it may complete the movement monitoring on basis of comparison of the first neighborhood information (the backup neighborhood information) to the second neighborhood information obtained after switching back to operate in the normal mode. The gateway device 1 10-i may switch back to the normal mode in response to regaining the external operating power supply (e.g. from the external power source PWR or from another external power source) without interruption in its operation before a shut-down due to the temporary power source 1 13 having run out of the charge or after a restart of the gateway device 1 10-i following a shut-down due to the temporary power source 1 13 having run out of the charge. In this regard, the control means 1 14 in the gateway device 1 10-i may be arranged to obtain, in response to switching to operate in the normal mode, the second neighborhood information and to compare the second neighborhood information to the first neighborhood information. In this scenario, the collection of the second neighborhood information may be carried during a predefined time period (immediately) following the restart of the gateway device 1 10-i (which time period hence serves as the second time period), and the comparison may be carried out after the predefined time period has elapsed.

A substantial change in the neighborhood of the gateway device 1 10-i within the positioning arrangement 100 may serve as an indication of movement of the gateway device 1 10-i. The movement of gateway device 1 10-i may involve a change of location of the gateway device 1 10-i, a change of orientation of the gateway device 1 10-i, or both, Hence, the control means 1 14 in the gateway device 1 10-i may be arranged to initiate, in response to the comparison of the first neighborhood information to the second neighborhood information indicating a substantial difference, transmission of one or more gateway-moved indication messages. Herein, a substantial difference may involve one or more of the following:

- a gateway device 1 10 included in the first neighborhood information completely missing from the second neighborhood information;

- a gateway device 1 10 not included in the first neighborhood information included in the second neighborhood information;

- a change in value of the extracted RSSI for a given gateway device 100 included in both the first neighborhood information and the second neighborhood information exceeding a predefined threshold (defined e.g. as a percentage, e.g. 20 %);

- a direction of arrival for a given gateway device 100 included in both the first neighborhood information and the second neighborhood information exceeding a predefined threshold (defined e.g. as an angle, e.g. 10 °).

According to an example embodiment, the control means 1 14 in a gateway device 1 10- i may be arranged to monitor movement of the gateway device 1 10-i during the low- power mode, i.e. during provision of the operation power from the temporary power source 1 13. As an example in this regard, the control means 1 14 may be arranged to implement the movement monitoring by comparing the first neighborhood information with the second neighborhood information obtained on basis of GW information extracted during operation in the low-power mode. In this regard, the control means 1 14 in the gateway device 1 10-i may be arranged to obtain the second neighborhood information during the low-power mode operation and to compare the second neighborhood information to the first neighborhood information. The collection of the further neighborhood information may be carried out during a predefined time period (immediately) following the switch to operate in the low-power mode (which time period hence serves as the second time period), and the comparison may be carried out after the predefined time period has elapsed. Moreover, the collection of the second neighborhood information and the comparison may be repeated periodically (e.g. at predefined time interval) during operation in the low-power mode. The control means 1 14 in the gateway device 1 10-i may be arranged to initiate the transmission of the gateway-moved indication messages in response to the comparison between the first neighborhood information and the second neighborhood information indicating a substantial difference (thereby indicating a substantial change in the neighborhood of the gateway device 1 10-i). The significance of the change in the neighborhood information may be evaluated e.g. as described in the foregoing. According to an example embodiment, the control means 1 14 in a gateway device 1 10- i may be arranged to monitor movement of the gateway device 1 10-i during the normal mode even if no switch to the low-power mode has occurred. As an example in this regard, the control means 1 14 may be arranged to periodically obtain the second neighborhood information on basis of GW information extracted during a predefined time period (i.e. the second time period) during operation in the normal mode and to compare the second neighborhood information so obtained to the first neighborhood information after the predefined time period has elapsed. The control means 1 14 in the gateway device 1 10-i may be further arranged to initiate the transmission of the gateway-moved indication messages in response to the comparison between the first neighborhood information and the second neighborhood information indicating a substantial difference (thereby indicating a substantial change in the neighborhood of the gateway device 1 10-i). The significance of the change in the neighborhood information may be evaluated e.g. as described in the foregoing.

GW device detecting movement by using a sensor

As another example of the gateway device 1 10-i monitoring its movement, either during the normal mode or during the low-power mode, the gateway device 1 10-i may extract sensory information and implement movement detection on basis of the extracted sensory information. As an example in this regard, the gateway device 1 10- i may further include sensor means that is capable of detecting movement of the gateway device 1 10-i. The movement detection may involve detecting at least the extent of movement and possibly also direction of movement. As an example, the sensor means may comprise an accelerometer. The control means 1 14 in the gateway device 1 10-i may be further arranged to invoke transmission of the gateway-moved indication messages in response to detecting movement whose extent exceeds a predefined threshold distance, while the movement exceeding the predefined threshold distance may further result in the gateway device 1 10-i discontinuing transmission of outbound beacon messages and/or transmission of tracking messages. The predefined distance may be selected in accordance with the desired sensitivity to a change in location of the gateway device 1 10-i, e.g. by using a value in a range from a few meters to a few tens of meters. Referring back to transmission of the gate-moved message(s), the gateway-moved indication message includes at least the GW identifier to identify the source of the gateway-moved indication message. According to an example embodiment, the control means 1 14 in the gateway device 1 10-i may be configured to cause the first wireless communication means 1 12a to transmit the gateway-moved indication messages. A gateway-moved indication message may be transmitted e.g. as an advertising message that, in addition to the GW identifier, carries at least a status indication or an indication of other kind that identifies the message as the gateway- moved indication message. According to another example embodiment, the control means 1 14 in the gateway device 1 10-i may be arranged to cause, instead of or in addition to transmitting the gateway-moved indication messages via the first wireless communication means 1 12a, the second wireless communication means 1 12b to transmit the gateway-moved indication messages to the server device 120. In this scenario, a gateway-moved indication message may be provided as any message that, in addition to the GW identifier, carries at least a status indication or an indication of other kind that identifies the message as the gateway-moved indication message. As an example, the transmission of gateway-moved indication messages may be carried out according to a predefined schedule, which may define, for example, that a set of one or more gateway-moved indication messages is transmitted at predefined time intervals when a condition that indicates movement of the gateway device 1 10-i has been detected.

In a scenario where the gateway devices 1 10 are caused to transmit the gateway- moved indication messages via the first wireless communication means 1 12a, the other gateway devices may monitor such messages and forward any received such messages to the server device 120, the gateway device 1 10-i may receive a gateway- moved indication message from another gateway within operation range of the first wireless communication means 1 12a. Consequently, the gateway device 1 10-i may be arranged to inform, in response to receiving a gateway-moved indication message from another gateway device 1 10-j, the server device 120 about the change of location of the gateway device 1 10-j identified in the received gateway-moved indication message. This may involve the control means 1 14 causing the gateway device 0-i to transmit a message in this regard to the server device 120 by using the second wireless communication means 1 12b, e.g. by forwarding the information received in the gateway-moved indication message via the second wireless communication means 1 12b. Upon reception of such message the server device 120 is able to invoke necessary action(s) due to assumed relocation of the gateway device concerned.

As described in the foregoing, the gateway devices 1 10 may be arranged to transmit the GW information messages to the server device 120, which is hence able to receive GW information messages from a plurality of gateway devices 1 10, each of which is assumed to occupy a predefined location within or close to the area of interest and which predefined location is known by the server device 120. As described in the foregoing, a GW information message from a gateway device 1 10-i may report information pertaining to single other gateway device 1 10 as extracted by the gateway device 1 10-i or it may report information pertaining to a number of gateway devices in the neighborhood of the gateway device 1 10-i. Whichever the case may be, the server device 120 may be arranged to establish, on basis of the information received in the GW information messages, the neighborhood information for each of the gateway devices 1 10. Moreover, a change in the neighborhood information derived for a given gateway device 1 10-i may serve as an indication of the certain gateway device 1 10 e.g. malfunctioning or having been relocated from its predefined location.

According to an example embodiment, the control means 124 in the server device 120 may be arranged to monitor movement of a gateway device 1 10-i on basis of the neighborhood information stored in the server device 120. As an example in this regard, the server device 120 may be configured to store the information received in the GW information messages from a gateway device 100-i in the memory 125 and use the information so obtained as the neighborhood information for the gateway device 1 10-i. Moreover, the control means 124 in the server device 120 may use the neighborhood information to implement the movement monitoring for a gateway device 1 10-i by monitoring changes in the neighborhood information obtained in the server device 120 for one or more gateway devices 1 10.

As an example of movement monitoring in the server device 120, the control means 124 in the server device 120 may be arranged to compare the most recently obtained neighborhood information obtained for the gateway device 1 10-i to that obtained earlier and consider the gateway device 100-i to have changed its location in response to the comparison indicating a significant change in the neighborhood information the gateway device 1 10-i. The significance of the change in the neighborhood information may be evaluated e.g. as described in the foregoing.

As another example of movement monitoring in the server device 120, the control means 124 in the server device 120 may be arranged to analyze neighborhood information obtained for two or more gateway devices 1 10 other than the gateway device 1 10-i and consider the gateway device 100-i to have changed its location in response to at least the most recently obtained neighborhood information for at least two other indicating a significant change to that obtained earlier with respect to the GW information pertaining to the gateway device 1 10-i. Herein, a significant change may comprise e.g. one or more of the following:

- a gateway device 1 10-i is included in the most recently obtained neighborhood information for a gateway device 1 10-j while it was absent from the earlier neighborhood information for the gateway device 1 10-j and the gateway device 1 10-i is absent from the most recently obtained neighborhood information for a gateway device 1 10-j while it was included in the earlier neighborhood information for the gateway device 1 10-k (in other words, the gateway device 1 10-i has appeared to the neighborhood of the gateway device 1 10-j while it has disappeared from the neighborhood of the gateway device 1 10-k);

- an increase in RSSI indicated for a gateway device 1 10-i from a value indicated in the earlier neighborhood information for the gateway device 1 10-j to that indicated in the most recently obtained neighborhood information for the gateway device 1 10-j exceeding a predefined threshold and a decrease in RSSI indicated for a gateway device 1 10-i from a value indicated in the earlier neighborhood information for the gateway device 1 10-k to that indicated in the most recently obtained neighborhood information for the gateway device 1 10-k exceeding the predefined threshold (where the predefined threshold may be defined as a percentage, e.g. 20 %).

The control means 124 in the server device 120 may be arranged to invoke, in response to detecting a change of location for the gateway device 1 10-i, an alarm via a user interface of the server device 120 or via an user interface of another device that is coupled or connected to the server device 120.

In the foregoing, the operation of the positioning arrangement 100 is described with references to the gateway devices 1 10 using the second wireless communication means 1 12b in communication with the server device 120. As an exemplifying variation of this approach, the communication between the gateway device 1 10-i and the server device 120 may be provided by using a wired communication means that may be included in the communication portion 1 12 of the gateway device 1 10-i. While in the foregoing the operation of the positioning arrangement 100 is described in context of the gateway devices 1 10, the server device 120 and the tag devices 130, the respective operation may be also described as steps of a method. As an example in this regard, Figure 5 illustrates a method 200 according to an example embodiment. The method 200 serves as a method for operating a gateway device 100-i of the positioning arrangement 100. The method 200 may be carried out e.g. in the computing device 210 or another device to cause the device to operate as the gateway device 1 10 of the positioning arrangement 100.

The method 200 may comprise receiving advertising messages from one or more tracked devices 130, as indicated in block 210. As described in the foregoing, these advertising messages may be transmitted e.g. by using the first wireless communication means 1 12a. The method 200 may further comprise transmitting tracking messages to the server device 120, wherein a tracking message includes tracking information extracted on basis of a received advertising message, as indicated in block 220. As described in the foregoing, the tracking messages may be transmitted using the second wireless communication means 1 12b,

The method 200 further comprises receiving inbound beacon messages from one or more other gateway devices 1 10 and transmitting outbound beacon messages to other gateway devices 1 10, as indicated in block 230. The beacon messages may be transmitted and received using the first wireless communication means 1 12a. The method 200 further comprises extracting the GW information on basis of inbound beacon messages, as indicated in block 240, and obtaining the neighborhood information on basis of GW information extracted on basis of inbound beacon messages received from one or more other gateway devices 1 10, as indicated in block 250.

The method 200 further comprises monitoring, in response to switching to operate the gateway device 1 10 in the low-power mode, movement of the gateway device 1 10 on basis of the obtained neighborhood information, as indicated in block 260 and transmitting one or more gateway-moved indication messages in response to detecting movement of the gateway device 1 10, as indicated in block 270. As described in the foregoing, the gateway-moved indication messages may be transmitted using the first wireless communication means 1 12a or the second wireless communication means 1 12b,

The method 200 may be varied in a number of ways in context of the present invention, e.g. in accordance with the examples described in the foregoing in context of description of operation of the positioning arrangement 100 and/or any of its components (e.g. the gateway devices 1 10, the server device 120 and the tag devices 130).

Referring back to Figure 2, the processor 1 16 is configured to read from and write to the memory 1 15. Although the processor 1 16 is depicted as a single component, the processor 1 16 may be implemented as one or more separate components. Similarly, although the memory 1 15 is illustrated as a single component, the memory 1 15 may be implemented as one or more separate components, some or all of which may be integrated/removable and/or may provide permanent / semi-permanent/ dynamic/cached storage.

The computer program code 1 17 stored in the memory 1 15 comprises computer program comprising computer-executable instructions that control the operation of the computing device 210 when loaded into the processor 1 16. As an example, the computer program may include one or more sequences of one or more instructions. The processor 126 is able to load and execute the computer program by reading the one or more sequences of one or more instructions included therein from the memory 1 15. The one or more sequences of one or more instructions may be configured to, when executed by the processor 1 16, cause the computing device 210 to carry out operations, procedures and/or functions described in the foregoing in context of the gateway device 1 10. Hence, the computing device 210 may comprise at least one processor 1 16 and at least one memory 1 15 including the computer program code 1 17 for one or more programs, the at least one memory 1 15 and the computer program code 1 17 configured to, with the at least one processor 1 16, cause the computing device 210, 300 to perform operations, procedures and/or functions described in the foregoing in context of the gateway device 1 10. The above description concerning operation of the processor 1 16, the memory 1 15 and the computer program code 1 17 of the computing device 210 also applies, mutatis mutandis, also to operation of the processor 126, the memory 125 and the computer program code 127 of the computing device 220 as well as to operation of the processor 136, the memory 135 and the computer program code 137 of the computing device 230.

The computer program may be comprised in a computer program product. According to an example embodiment, the computer program product may comprise a non- transitory computer-readable medium. Thus, the computer program product may be provided e.g. as a computer program product that comprises at least one computer- readable non-transitory medium having program code stored thereon, the program code, when executed in the respective computing device 210, 220, 230, causing the device at least to perform operations, procedures and/or functions described in the foregoing in context of the respective element of the positioning arrangement 100. The computer-readable non-transitory medium may comprise a memory device or a record medium such as a CD-ROM, a DVD, a Blu-ray disc or another article of manufacture that tangibly embodies the computer program. As another example, the computer program may be provided as a signal configured to reliably transfer the computer program. Reference(s) to a processor should not be understood to encompass only programmable processors, but also dedicated circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processors, etc.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not.

Claims

1 . A method for operating a gateway device, the method comprising receiving inbound beacon messages from one or more other gateway devices and transmitting outbound beacon messages to other gateway devices using a first wireless communication means; extracting gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices; monitoring movement of the gateway device on basis of the neighborhood information; and transmitting, using the first wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the gateway device. 2. A method according to claim 1 , further comprising receiving, using the first wireless communication means, advertising messages from one or more tracked devices and transmitting, using a second wireless communication means, tracking messages to a server device, a tracking message including tracking information extracted on basis of a received advertising message. 3. A method according to claim 1 or 2, wherein said obtaining comprises obtaining first neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received during a first time period, and obtaining second neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received during a second time period that follows the first time period, and wherein said monitoring comprises, in response to completion of the second time period, comparing the first neighborhood information to the second neighborhood information; and detecting a movement of the gateway in response to said comparison indicating a substantial difference.

A method according to claim 3, further comprising switching to operate the gateway device in a low-power mode in response to the gateway device switching to draw operating power from a temporary power source within the gateway device instead of an external power source, wherein said first time period is a time period before switching to operate the gateway device in the low-power mode and wherein said second time period is a time period after switching to operate the gateway device in the low-power mode.

A method according to claim 4, wherein said obtaining comprises obtaining the second neighborhood information in response to one of the following:

- switching to operate the gateway device in a low-power mode, and

- the gateway device switching to draw operating power from an external power source following a period of operation in the low-power mode.

A method according to claim 4 or 5, further comprising storing, in response to switching to operate the gateway device in the low-power mode, the most recently obtained first neighborhood information in persistent memory in the gateway device.

A method according to any of claims 4 to 6, further comprising initiating, in response to switching to operate the gateway device in the low-power mode, transmission of one or more loss-of-power indication messages using the first wireless communication means.

A method according to claim 3, wherein said obtaining comprises periodically obtaining the second neighborhood information.

A method according to any of claims 3 to 8, wherein said obtaining comprises periodically obtaining the first neighborhood information.

0. A method according to claim 9, further comprising periodically storing the most recently obtained first neighborhood information in persistent memory in the gateway device.

1 . A method according to any of claims 3 to 10, wherein said extracting comprises extracting a gateway identifier assigned for a source of an inbound beacon messages from said inbound beacon message; and wherein one or more of the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: a gateway identifier that is included in the first neighborhood information not included in the second neighborhood information, a gateway identifier that is included in the second neighborhood information not included in the first neighborhood information,

2. A method according to claim 1 1 , wherein said extracting further comprises deriving a received signal strength indication, RSSI, on basis of an inbound beacon message to obtain a RSSI associated with the gateway identifier received in the same inbound beacon message; and wherein the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: for a given gateway identifier included in both the first neighborhood information and the second neighborhood information, the RSSI associated with the given gateway identifier in the first neighborhood information differs from that in the second neighborhood information by at least a first predefined amount.

3. A method according to claim 1 1 or 12, wherein said extracting further comprises receiving a direction of arrival indication associated with the gateway identifier received in an inbound beacon message; and wherein the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: for a given gateway identifier included in both the first neighborhood information and the second neighborhood information, the direction of arrival associated with the given gateway identifier in the first neighborhood information differs from that in the second neighborhood information by at least a predefined second amount.

14. A method according to any of claims 1 to 13, further comprising invoking one or more of following in response to switching to operate the gateway device in the low-power mode: discontinue reception of inbound beacon messages; discontinue transmission of outbound beacon messages or reduce transmission rate of the outbound beacon messages; and discontinue operation of any further communication means in the gateway device.

15. A method according to any of claims 1 to 14, further comprising receiving, using the first wireless communication means, a gateway-moved indication message from another gateway device; and transmitting, using a second communication means, information received in the gateway-moved indication message to a server device.

16. A method according to any of claims 1 to 14, further comprising extracting gateway information on basis of inbound beacon messages; and transmitting, using a second communication means, a gateway information message including information extracted on basis of inbound beacon messages from one or more other gateway devices to a server device.

17. An apparatus comprising means for performing the actions of the method according to any of claims 1 to 16.

18. An apparatus comprising a communication portion comprising at least a first wireless communication apparatus for receiving inbound beacon messages from one or more other devices and for transmitting outbound beacon messages to other devices; and a control portion for operating the apparatus as a gateway device, the control portion configured to extract gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices; monitor movement of the apparatus on basis of the neighborhood information; and transmit, using the first wireless communication apparatus, one or more gateway- moved indication messages in response to detecting movement of the apparatus.

19. An apparatus according to claim 18, wherein the control portion is configured to receive, using the first wireless communication apparatus, advertising messages from one or more tracked devices and transmit, using a second wireless communication apparatus provided in the communication portion, tracking messages to a server device, a tracking message including tracking information extracted on basis of a received advertising message.

20. An apparatus according to claim 18 or 19, wherein said obtaining comprises obtaining first neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received during a first time period, and obtaining second neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received during a second time period that follows the first time period, and wherein said monitoring comprises, in response to completion of the second time period, comparing the first neighborhood information to the second neighborhood information; and detecting a movement of the gateway in response to said comparison indicating a substantial difference. 21 . An apparatus according to claim 20, wherein the control portion is configured to switch to operate the apparatus in a low-power mode in response to the apparatus switching to draw operating power from a temporary power source within the apparatus instead of an external power source, wherein said first time period is a time period before switching to operate the apparatus in the low-power mode and wherein said second time period is a time period after switching to operate the apparatus in the low-power mode.

22. An apparatus according to claim 21 , wherein the control portion is configured to obtain the neighborhood information in response to one of the following:

- switching to operate the apparatus in a low-power mode, and - the apparatus switching to draw operating power from an external power source following a period of operation in the low-power mode.

23. An apparatus according to claim 21 or 22, wherein the control portion is configured to store, in response to switching to operate the apparatus in the low- power mode, the most recently obtained first neighborhood information in persistent memory in the apparatus.

24. An apparatus according to any of claims 21 to 23, wherein the control portion is configured to initiate, in response to switching to operate the apparatus in the low-power mode, transmission of one or more loss-of-power indication messages using the first wireless communication apparatus. 25. An apparatus according to claim 20, wherein the control portion is configured to periodically obtain the second neighborhood information.

26. An apparatus according to any of claims 20 to 25, wherein the control portion is configured to periodically obtain the first neighborhood information.

27. An apparatus according to claim 26, wherein the control portion is configured to periodically store the most recently obtained first neighborhood information in persistent memory in the apparatus.

28. An apparatus according to any of claims 20 to 27, wherein said extracting comprises extracting a gateway identifier assigned for a source of an inbound beacon messages from said inbound beacon message; and wherein one or more of the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: a gateway identifier that is included in the first neighborhood information not included in the second neighborhood information, a gateway identifier that is included in the second neighborhood information not included in the first neighborhood information.

29. An apparatus according to claim 28, wherein said extracting further comprises deriving a received signal strength indication, RSSI, on basis of an inbound beacon message to obtain a RSSI associated with the gateway identifier received in the same inbound beacon message; and wherein the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: for a given gateway identifier included in both the first neighborhood information and the second neighborhood information, the RSSI associated with the given gateway identifier in the first neighborhood information differs from that in the second neighborhood information by at least a first predefined amount.

30. An apparatus according to claim 28 or 29, wherein said extracting further comprises receiving a direction of arrival indication associated with the gateway identifier received in an inbound beacon message; and wherein the following serve as an indication of a substantial difference between the first neighborhood information and the second neighborhood information: for a given gateway identifier included in both the first neighborhood information and the second neighborhood information, the direction of arrival associated with the given gateway identifier in the first neighborhood information differs from that in the second neighborhood information by at least a predefined second amount.

31 . An apparatus according to any of claims 18 to 30, wherein the control portion is further configured to invoke one or more of following in response to switching to operate the apparatus in the low-power mode: discontinue reception of inbound beacon messages; discontinue transmission of outbound beacon messages or reduce transmission rate of the outbound beacon messages; and discontinue operation of any further communication apparatus in the apparatus.

32. An apparatus according to any of claims 18 to 31 , wherein the control portion is configured to receive, using the first wireless communication apparatus, a gateway-moved indication message from another gateway device; and transmit, using a second communication apparatus in the communication portion, information received in the gateway-moved indication message to a server device.

33. An apparatus according to any of claims 18 to 31 , wherein the control portion is configured to extract gateway information on basis of inbound beacon messages; and transmitting, using a second communication means, a gateway information message including information extracted on basis of inbound beacon messages from one or more other gateway devices to a server device.

34. An apparatus comprising at least one processor and a memory storing a program of instructions, wherein the memory storing the program of instructions is configured to, with the at least one processor, configure the apparatus to operate as a gateway device, comprising: receiving, using a wireless communication apparatus, inbound beacon messages from one or more other gateway devices and transmitting, using the wireless communication apparatus, outbound beacon messages to other gateway devices; extracting gateway information on basis of inbound beacon messages and obtaining neighborhood information on basis of the gateway information extracted on basis of inbound beacon messages received from one or more other gateway devices; monitoring movement of the apparatus on basis of the neighborhood information; and transmitting, using the first wireless communication means, one or more gateway-moved indication messages in response to detecting movement of the apparatus.

A computer program comprising computer readable program code configured to cause performing, when said program code is run on a computing apparatus, at least a method according to any of claims 1 to 16.

A computer program product comprising at least one computer readable non- transitory medium having program code stored thereon, the program which when executed by an apparatus cause the apparatus at least to perform a method according to any of claims 1 to 16.