WO2017051062A1

WO2017051062A1 - Positioning method

Info

Publication number: WO2017051062A1
Application number: PCT/FI2015/050632
Authority: WO
Inventors: Veli-Matti KOLMONEN
Original assignee: Nokia Technologies Oy
Priority date: 2015-09-23
Filing date: 2015-09-23
Publication date: 2017-03-30

Abstract

A method and apparatus are disclosed for receiving, at a fixed node (40) positioning information from an intermediary mobile tag (10) enabling the position of the intermediary mobile tag (10) to be determined; and positioning information from the intermediary mobile tag (10) relating to the position of a second mobile tag (20, 30) with respect to the intermediary mobile tag (10); and estimating a position of the second tag (20, 30) using the information received from the intermediary tag relating to the second tag. A method and apparatus are also disclosed for receiving, at an intermediary mobile tag (10), a data packet from a second mobile tag (20, 30), determining positioning information of the second mobile tag (20, 30) with respect to the intermediary mobile tag (10) based on an analysis of the data packet, and sending the positioning information to a system node (40).

Description

POSITIONING METHOD

Field

The specification relates to positioning devices.

Background

High accuracy indoor positioning requires novel systems and solutions that are specifically developed for indoor positioning. The "traditional" positioning technologies used mainly outdoors, such as GPS, WiFi- and cellular-positioning technologies, generally cannot deliver a satisfactory performance indoors that would enable seamless navigation experience in both environments. Typically, there are issues with accuracy, coverage and floor detection (3D) that are difficult to achieve with systems and signals that were not originally designed for the indoor use cases. Since the inside of buildings is not free space, the accuracy of indoor positioning systems may be significantly impacted by obstructions and interference of various kinds.

Summary

In a first aspect, this specification describes a method comprising receiving, at a fixed node positioning information from an intermediary mobile tag enabling the position of the intermediary mobile tag to be determined; and positioning information from the intermediary mobile tag relating to the position of a second mobile tag with respect to the intermediary mobile tag; and estimating a position of the second tag using the information received from the intermediary tag relating to the second tag.

The positioning information from the intermediary tag relating to the position of the second tag with respect to the first tag may be acquired by the intermediary tag from the second tag. The position of the intermediary tag may be determined by determining an angle of arrival of a packet received from the intermediary tag.

Positioning information from the intermediary tag relating to the position of the second tag with respect to the intermediary tag may comprise a received signal strength indication value determined by the intermediary tag and an automatic gain control value of the intermediary tag. The method may further comprise calculating a distance between the intermediary tag and the second tag using information received from the intermediary tag.

The method may further comprise sending a request to the intermediary tag to forward positioning information relating to one or more second mobile tags.

The method may further comprise receiving positioning information relating to a second tag from at least three intermediary tags, estimating a position of the second tag with respect to each of the plurality of intermediary tags and performing a trilateration operation to determine a position of the second tag.

The method may further comprise storing a transmit signal strength value relating to the second mobile tag and the transmit signal strength valueis used to facilitate the position estimation of the second mobile tag.

In a second aspect, this specification describes a method method comprising receiving, at an intermediary mobile tag, a data packet from a second mobile tag, determining positioning information of the second mobile tag with respect to the intermediary mobile tag based on an analysis of the data packet, and sending the positioning information to a system node.

The positioning information of the second mobile tag with respect to the intermediary mobile tag may be a received signal strength indication value. The method may further comprise the intermediary tag requesting positioning

information relating to the second mobile tag from the second mobile tag.

The method may further comprise the intermediary mobile tag measuring a received signal strength indication value from a wireless message received from the second tag.

The method may further comprise receiving data packets from each of a plurality of second mobile tags, determining positioning information from each of the second mobile tags and forwarding the positioning information of a predetermined number of the second mobile tags that are closest to the intermediary tag to the system node.

The intermediary mobile tag may be BLE-enabled. In a third aspect, this specification describes a computer program comprising instructions that, when executed by a computing apparatus, cause the computing apparatus to perform the method of the first or second aspect. In a fourth aspect, this specification describes an apparatus comprising at least one processor; at least one memory having computer-readable instructions stored thereon, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to receive positioning information from an intermediary mobile tag enabling the position of the intermediary mobile tag to be determined; and positioning information from the intermediary mobile tag relating to the position of a second mobile tag with respect to the intermediary mobile tag; and estimate a position of the second tag using the information received from the intermediary tag relating to the second tag.

In a fifth aspect, this specification describes an apparatus comprising at least one processor; at least one memory having computer-readable instructions stored thereon, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to receive, a data packet from a second mobile tag, determine positioning information of the second mobile tag with respect to the apparatus based on an analysis of the data packet, and send the positioning information to a system node.

In a sixth aspect, this specification describes a computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, causing performance of receiving, at a fixed node positioning information from an intermediary mobile tag enabling the position of the intermediary mobile tag to be determined; and positioning information from the intermediary mobile tag relating to the position of a second mobile tag with respect to the intermediary mobile tag; and estimating a position of the second tag using the information received from the intermediary tag relating to the second tag. In a seventh aspect, this specification describes a computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, causing performance of receiving, at an intermediary mobile tag, a data packet from a second mobile tag, determining positioning information of the second mobile tag with respect to the intermediary mobile tag based on an analysis of the data packet, and sending the positioning information to a system node. In an eighth aspect, this specification describes an apparatus comprising means for receiving, at a fixed node positioning information from an intermediary mobile tag enabling the position of the intermediary mobile tag to be determined; and positioning information from the intermediary mobile tag relating to the position of a second mobile tag with respect to the intermediary mobile tag; and means for estimating a position of the second tag using the information received from the intermediary tag relating to the second tag.

In a ninth aspect, this specification describes an apparatus comprising: means for receiving, at an intermediary mobile tag, a data packet from a second mobile tag, means for determining positioning information of the second mobile tag with respect to the intermediary mobile tag based on an analysis of the data packet, and means for sending the positioning information to a system node. Brief description of the drawings

For a more complete understanding of the methods, apparatuses and computer-readable instructions described herein, reference is now made to the following descriptions taken in connection with the accompanying drawings in which: Figure l is a schematic diagram illustrating an indoor environment;

Figure 2 is a flow chart illustrating various embodiments;

Figure 3 is a schematic block diagram illustrating a High Accuracy Indoor Positioning tag;

Figure 4 is a schematic block diagram illustrating a Cost Optimised Indoor Positioning tag;

Figure 5 is a schematic block diagram illustrating a system node; and Figure 6 shows a storage means. Detailed description

In the following description reference is made to High Accuracy Indoor Positioning (HAIP) and Cost Optimised Indoor Positioning (COIP) which are indoor positioning systems that use HAIP and COIP locators, respectively, to determine the positions of mobile tags. COIP locators and HAIP locators may be provided in an indoor environment to track the mobile tags. HAIP

High-Accuracy Indoor Positioning (HAIP) tracks the position of Bluetooth LE tags using ceiling- installed locators which perform Angle-of- Arrival measurement on BLE advertisement messages transmitted by the tags. However, the effective tracking area under a locator is a focused conical area, so multiple locators are needed. HAIP also requires relatively intensive computational operations. If a tag is obscured with respect to the HAIP locator, it can be difficult to locate the tag. COIP

COIP mode provides lower accuracy positioning than HAIP mode. However, the infrastructure is less expensive and can involve less complex computational operations to determine a tag location. COIP is therefore convenient for locations and situations where lower accuracy is acceptable to a user.

Non-stationary objects such as doors, furniture, and people can pose a problem for HAIP systems since they can affect the signal strength in dynamic, unpredictable ways.

Embodiments of the invention provide a system in which High-Accuracy Indoor

Positioning (HAIP) tags that are obscured with respect to the locator can still be tracked using the HAIP system by relaying information from the obscured tag via a second HAIP tag which is unobscured with respect to the locator.

While the COIP mode is useful in situations where a medium level of accuracy is satisfactory, a high accuracy positioning mode may be required in other situations.

Embodiments of the invention provide a system in which a High-Accuracy Indoor Positioning (HAIP) tag can be used to relay information received from COIP tags to improve the positioning accuracy of the COIP tags.

Figure 1 shows a communication system 100 in which a HAIP mobile tag 10 is used as an intermediary device to relay information received from a second HAIP mobile tag 20 and/or a COIP mobile tag 30 to a system node 40. The system node 40 may be connected to a server 45 by a wired or wireless connection. The HAIP mobile tag 10 which is used as an intermediary device is a HAIP-enabled tag. In this example, the second mobile tag 20 is also an HAIP-enabled tag and the third mobile tag 30 is a COIP enabled tag.

In this example, an obstruction 50 occurs between the second mobile tag 20 and the system node 40. The obstruction 50 may be anything which prevents a signal from the second mobile tag 20 reaching the system node 40. In a hospital, a person may place a metal trolley between the mobile tag 20 and the system node 40 which acts to block the signal sent from the mobile tag 20 to the system node 40. In the absence of the obstruction 50, the mobile tag 20 would transmit packets to the system node 40 enabling the system node 40 to determine the position of the mobile tag 20 using the HAIP mode.

The deterioration in HAIP ability may alternatively be caused by other factors such as severe radio interference, or the tag 20 being outside the high accuracy range of the system node 40, or if there is severe multipath interference where, in multipath propagation, the radio waves propagate through multiple paths. When these waves reach the system node 40 they may cause severe performance degradation so that the system node 40 cannot utilise the high accuracy features of the tag 20. However, the system 100 may still be able to detect low accuracy level information from the tag 20. Low accuracy level information may include a received signal strength indication (RSSI) determined from packet received from the tag 20.

Figure 2 is a flow chart illustrating operations performed by the system 100 and, in particular, the node 40, intermediary tag 10 and tags 20, 30 whose position is to be determined. The tags 20, 20 are hereinafter referred to as target tags since it is the position of these tags which is of interest.

The node 40 first positions the intermediary HAIP tag 10, which can be positioned accurately by the node 40 since it is not obscured. At operation 2.1, the tag 10 periodically transmits BLE advertisement messages which are received by the system node 40. The system node 40 comprises an antenna array, BLE transceiver, and RF switch and appropriate computer program instructions to carry out Angle of Arrival calculations on the received packets. As such, the position of the tag 10 may be determined using the HAIP system. The intermediary tag 10 may request positioning information from the target tag 20 at operation 2.2. This may take the form of a request message sent by the intermediary tag 10 to the tag 20.

In response, the tag 20 sends a message to the intermediary tag 10 at operation 2.3. The message may contain information such as an identifier of the tag 20. At operation 2.4, the intermediary tag 10 measures low accuracy positioning information of the tag 20. The low accuracy positioning information may be an RSSI value. In alternative embodiments, a time-of-flight metric may be used. For many positioning purposes the distance between the tags and the system node is of interest. One way to determine these distances is using the received RF power as basis. An indication of the received signal strength can be acquired from the RSSI but for more accurate implementations the receiver and transmitter antenna gains, transmitted signal strength, automatic gain control (AGC) value of the tag 10, and the received signal strength is required. The tag 10 comprises an AGC module and an analog-to-digital converter (not shown). The AGC module is used to adjust the power level of the received signal in the receiver to a level suitable for the analog-to-digital converter. Using this value along with information of the signal propagation the distance which the signal has travelled between the tag 20 and the intermediary tag 10 can be calculated.

The received power is related to the distance in the following way (omitting the AGC value) using the Friis transmission equation.

P_r = P_t G_t x G_r x 0 4 d)² (Equation 1) where

P_r is the received signal strength

P_t is the transmitted signal strength

G_t is the gain of the transmitter antenna

G_r is gain of the receiver antenna

λ is the wavelength

d is the distance

The intermediary tag 10 forwards the low accuracy positioning information to the node 40 at operation 2.5 together with the tag identifier of the tag 20. The intermediary tag 10 may also transmit an AGC value for the tag 10 to the node 40. The system 100 may store (e.g. at the node 40) the transmitted signal strength indication (P_t) information for each tag in the system 100. The transmitted signal strength indication (P_t) value may be set to the same value for all tags in the system. The node 40 may also store the gain values for each of the tags.

The transmitted signal strength indication information and gain values do not need to be transmitted since the system owner or administrator can control the configuration of the tags used in the system. For example, in a hospital environment the hospital administrator can control which tags are used in the system and hence they can set the transmit signal strength and the gain value for each tag in the system. This information may then be stored at the node 40. In some embodiments, the transmit signal strength indicator values and gain values may be set to be the same for all tags. As such, it is not necessary for the tag 10 to forward this information from the tag 20 to the node 40. In some embodiments, the tag 10 takes into account the AGC value of tag 20 by adjusting the received signal strength indicator accordingly, and then transmits this information to the node 40.

At operation 2.6, the node 40 calculates the distance between the tag 10 and the tag 20 or tag 30 using Equation 1. The node 40 estimates a position of the tag 20 based on the information relating to the position of the intermediary tag 10 together with the calculated distance value based on the information received from the intermediary tag and the transmitted signal strength indication information and gain information stored by the system 100.

The node 40 may receive positioning information relating to a particular target tag from at least three intermediary tags 10. The node 40 may then estimate a position of the target tag with respect to each of the plurality of intermediary tags and perform a trilateration operation to determine a position of the target tag.

In the same way, the COIP tag 30 may be positioned more accurately than conventionally provided by COIP systems.

The relaying of the information by the intermediary tag 10 may be done in a number of ways.

In some embodiments, each HAIP tag may be configured to periodically send messages addressed to other tags in the system. The tags that receive the periodic messages determine which tags are among the N nearest based on an RSSI value of each received packet and forward the information received from those tags to the node 40. In some embodiments, a tag identifier of the target tag, received signal strength, AGC values are forwarded from the intermediary tag to the node 40 in relation to the N nearest target tags. This information may take up, for example, 3-8 bytes. The number of obstructed high or low accuracy tags for which information can be forwarded is dependent on the used radio system. For example, for the Bluetooth Low Energy (Bluetooth Smart) system, the advertisement payload size is 29 bytes. If the intermediary tag 10 is also required to send sensor data and can therefore use only 20 bytes for relaying information, the number tags whose information can be relayed may be in the region of approximately 2-6 tags. In some embodiments, each HAIP tag stores computer readable instructions instructing the tag to periodically send request messages for RSSI information from other tags in the system 100. The other tags in the system then respond with a reply message from which RSSI information can be determined. Once RSSI information has been determined, this information is forwarded to the node 40.

In some embodiments, the node 40 sends a request to one or more HAIP tags in the system 100 to obtain RSSI information from a particular tag of interest. A user may be aware that a particular tag may be missing and inputs the tag identifier into a computer in communication with the node 40. The node 40 then sends a request to one or more HAIP tags to send a request for RSSI data from the tag having the identifier entered by the user.

Filtering of the high accuracy tags and concentration to only the obstructed high and low accuracy tags can be implemented by either filtering the processed packets based on tag identifier or by examining the received packet structure as to whether the packet contains high accuracy information of sufficient level or a lack thereof.

The node 40 may be aware of the obstructed high and low accuracy tags since the node 40 can still determine RSSI data based on packets received directly from these tags. However, the node 40 may be initially unaware of which high accuracy tags are in communication with the obstructed or low accuracy tags and which could act as intermediary tags. In some embodiments, the node 40 can create a connection to the high accuracy tag 10 (for example by sending a query message) and query the tag 10 whether the tag 10 is in communication with the obstructed high or low accuracy tags.

If the tag 10 responds by indicating that it is not in communication with the requested tag, the node 40 can record this information and limit the possible locations of where the obstructed or low accuracy tag is. If the tag 10 is in communication with the requested tag the high accuracy tag 10 can send the requested information to the system node 40.

If the node 40 detects that the speed of positioning the tags 20 or 30 is not sufficiently high, as is often the case for the low accuracy or impaired high accuracy systems, the system can create connection to the unobscured high accuracy tags 10 and request the required information of the obstructed high or low accuracy tags. COIP can rely on RSSI values from packets transmitted by the mobile tags 10. As packets are received at the various COIP locators 40, positioning approaches may be used to determine the tag location such as multilateration or fingerprinting using the RSSI data received at each of the COIP locators 40.

Alternatively, COIP mode may use Time of Flight calculations. Alternatively, COIP mode may make use of coordinates calculated using HAIP mode where it is known that the coordinates are likely to below an accuracy threshold, for example if the calculated coordinates are beyond a distance threshold from the fixed locators.

Figure 3 is a schematic block diagram of a HAIP positioning tag 10, 20. The positioning tag 10, 20 comprises a transceiver 200 for transmitting wireless messages such as BLE advertisement messages and an antenna 201. The positioning tag 10, 20 also comprises a processor 210 and a storage device 220. The storage device comprises non-volatile memory 221 and volatile memory 222. The non-volatile memory is provided with a Bluetooth module 221A and computer-readable code i.e. programming instructions 221B. The Bluetooth module 221A contains computer readable instructions to cause the tag 10, 20 to transmit packets signals/positioning packets according to the BLE standard. The programming instructions 221B relate to the particular functionality of the positioning tag 10, 20 in embodiments of the present invention. The programming instructions 221B allow sent packets to be processed in accordance with the High Accuracy Indoor

Positioning (HAIP) solution, for example as described at http://www.in-location- alliance.com. Furthermore, the programming instructions 221B are configured to provide the relaying functionality described above.

Figure 4 is a schematic block diagram of a COIP positioning tag 30. The positioning tag 30 comprises a transceiver 300 for transmitting wireless messages and an antenna 301. The positioning tag 30 also comprises a processor 310 and a storage device 320. The storage device comprises non-volatile memory 321 and volatile memory 322. The nonvolatile memory 321 is provided with computer readable code 321A. The computer readable code 321A allows the particular functionality of the positioning tag 30 in embodiments of the present invention to be executed. Figure 5 is a schematic block diagram of the system node 40. The system node 40 comprises a transceiver 400 for transmitting wireless messages and an antenna array 401 and an RF switching module 402. The antenna array 401 and RF switching allow the system node 40 to perform angle-of-arrival (AoA) estimation by an angle-of-arrival module 403 for packets received from the intermediary tag 10. The system node 40 also comprises a processor 410 and a storage device 420. The storage device comprises nonvolatile memory 421 and volatile memory 422. The non-volatile memory 421 is provided with a Bluetooth module 421A and computer readable code 421B which allow the particular functionality of the system node 40 in embodiments of the present invention to be executed. The programming instructions 421B allow received packets to be processed in accordance with the High Accuracy Indoor Positioning (HAIP) solution. The system node 40 may be in wireless or wired communication with a server 45 or other remote apparatus.

Computer readable instructions, software and operating systems may be pre-programmed into the apparatuses 10, 20, 30, 40. Alternatively, the computer readable instructions, software and operating systems may arrive at the apparatuses 10, 20, 30, 40 via an electromagnetic carrier signal or may be copied from a physical entity 600 (see Figure 6) such as a computer program product, a memory device or a record medium such as a CD- ROM or DVD. The computer readable instructions, software and operating systems may provide the logic and routines that enables the devices/apparatuses 10, 20, 30, 40 to perform the functionality described above.

Whilst embodiments have been described using BTLE messages and HAIP systems, alternative low-power radio technologies may be used such as ZigBee or WiFi.

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

Embodiments of the present disclosure may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and/or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable medium may comprise a computer-readable storage medium that may be any tangible media or means that can contain or store the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer as defined previously. According to various embodiments of the previous aspect of the present disclosure, the computer program according to any of the above aspects, may be implemented in a computer program product comprising a tangible computer-readable medium bearing computer program code embodied therein which can be used with the processor for the implementation of the functions described above.

Reference to "computer-readable storage medium", "computer program product", "tangibly embodied computer program" etc, or a "processor" or "processing circuit" etc. should be understood to encompass not only computers having differing architectures such as single/multi processor architectures and sequencers/parallel architectures, but also specialised circuits such as field programmable gate arrays FPGA, application specify circuits ASIC, signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device as instructions for a processor or configured or configuration settings for a fixed function device, gate array, programmable logic device, etc.

By way of example, and not limitation, such "computer-readable storage medium" may mean a non-transitory computer-readable storage medium which may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage, or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. It should be understood, however, that "computer-readable storage medium" and data storage media do not include connections, carrier waves, signals, or other transient media, but are instead directed to non-transient, tangible storage media. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of "computer- readable medium".

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules. Also, the techniques could be fully implemented in one or more circuits or logic elements.

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

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

Claims

1. A method comprising:

receiving, at a fixed node:

positioning information from an intermediary mobile tag enabling the position of the intermediary mobile tag to be determined; and

positioning information from the intermediary mobile tag relating to the position of a second mobile tag with respect to the intermediary mobile tag; and

estimating a position of the second tag using the information received from the intermediary tag relating to the second tag.

2. The method of claim 1, wherein the positioning information from the intermediary tag relating to the position of the second tag with respect to the first tag is acquired by the intermediary tag from the second tag.

3. The method of claim 1 or 2, wherein the position of the intermediary tag is determined by determining an angle of arrival of a packet received from the intermediary tag.

4. The method of any preceding claim, wherein positioning information from the intermediary tag relating to the position of the second tag with respect to the intermediary tag comprises a received signal strength indication value determined by the intermediary tag and an automatic gain control value of the intermediary tag.

5. The method of any preceding claim, further comprising calculating a distance between the intermediary tag and the second tag using information received from the intermediary tag.

6. The method of any preceding claim, further comprising sending a request to the intermediary tag to forward positioning information relating to one or more second mobile tags.

7. The method of any preceding claim, further comprising receiving positioning information relating to a second tag from at least three intermediary tags, estimating a position of the second tag with respect to each of the plurality of intermediary tags and performing a trilateration operation to determine a position of the second tag.

8. The method of any preceding claim, further comprising storing a transmit signal strength value relating to the second mobile tag and the transmit signal strength value is used to facilitate the position estimation of the second mobile tag.

9. A method comprising:

receiving, at an intermediary mobile tag, a data packet from a second mobile tag, determining positioning information of the second mobile tag with respect to the intermediary mobile tag based on an analysis of the data packet, and

sending the positioning information to a system node.

10. The method of claim 9, wherein the positioning information of the second mobile tag with respect to the intermediary mobile tag is a received signal strength indication value.

11. The method of claim 9 or 10, further comprising the intermediary tag requesting positioning information relating to the second mobile tag from the second mobile tag.

12. The method of any of claims 9-11, further comprising the intermediary mobile tag measuring a received signal strength indication value from a wireless message received from the second tag.

13. The method of any of claims 9-12, further comprising receiving data packets from each of a plurality of second mobile tags, determining positioning information from each of the second mobile tags and forwarding the positioning information of a predetermined number of the second mobile tags that are closest to the intermediary tag to the system node.

14. The method of any preceding claim, wherein the intermediary mobile tag is BLE- enabled.

15. A computer program comprising instructions that, when executed by a computing apparatus, cause the computing apparatus to perform the method of any preceding claim.

16. Apparatus comprising:

at least one processor; at least one memory having computer-readable instructions stored thereon, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to:

receive:

estimate a position of the second tag using the information received from the intermediary tag relating to the second tag.

17. The apparatus of claim 16, wherein the positioning information from the intermediary tag relating to the position of the second tag with respect to the first tag is acquired by the intermediary tag from the second tag.

18. The apparatus of claim 16 or 17, wherein the position of the intermediary tag is determined by determining an angle of arrival of a packet received from the intermediary tag.

19. The apparatus of any of claims 16-18, wherein positioning information from the intermediary tag relating to the position of the second tag with respect to the intermediary tag comprises a received signal strength indication value determined by the intermediary tag and an automatic gain control value of the intermediary tag.

20. The apparatus of any of claims 16-19, further comprising calculating a distance between the intermediary tag and the second tag using information received from the intermediary tag.

21. The apparatus of any of claims 16-20, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to send a request to the intermediary tag to forward positioning information relating to one or more second mobile tags.

22. The apparatus of any of claims 16-21, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to receive positioning information relating to a second tag from at least three intermediary tags, estimating a position of the second tag with respect to each of the plurality of intermediary tags and performing a trilateration operation to determine a position of the second tag.

23. The apparatus of any of claims 16-22, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to store a transmit signal strength value relating to the second mobile tag and the transmit signal strength value is used to facilitate the position estimation of the second mobile tag.

24. Apparatus comprising:

at least one processor;

at least one memory having computer-readable instructions stored thereon, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to:

receive, a data packet from a second mobile tag,

determine positioning information of the second mobile tag with respect to the apparatus based on an analysis of the data packet, and

send the positioning information to a system node.

25. The apparatus of claim 24, wherein the positioning information of the second mobile tag with respect to the apparatus is a received signal strength indication value.

26. The apparatus of claim 24 or 25, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to request positioning information relating to the second mobile tag from the second mobile tag.

27. The apparatus of any of claims 24-26, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to measure a received signal strength indication value from a wireless message received from the second tag.

28. The apparatus of any of claims 24-27, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to receive data packets from each of a plurality of second mobile tags, determine positioning information from each of the second mobile tags and forward the positioning information of a predetermined number of the second mobile tags that are closest to the apparatus to the system node.

29. The apparatus of any of claims 24-28, wherein the apparatus is BLE-enabled.

30. A computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, causing performance of:

receiving, at a fixed node:

31. A computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, causing performance of:

sending the positioning information to a system node.

32. Apparatus comprising:

means for receiving, at a fixed node:

means for estimating a position of the second tag using the information received from the intermediary tag relating to the second tag.

33. Apparatus comprising:

means for receiving, at an intermediary mobile tag, a data packet from a second mobile tag,

means for determining positioning information of the second mobile tag with respect to the intermediary mobile tag based on an analysis of the data packet, and

means for sending the positioning information to a system node.