WO2017013304A1

WO2017013304A1 - Positioning method

Info

Publication number: WO2017013304A1
Application number: PCT/FI2015/050510
Authority: WO
Inventors: Joni Jantunen; Veli-Matti KOLMONEN; Olli Oskari Koskimies; Hannu Laine; Ilari Teikari
Original assignee: Nokia Technologies Oy
Current assignee: Nokia Technologies Oy
Priority date: 2015-07-23
Filing date: 2015-07-23
Publication date: 2017-01-26
Anticipated expiration: 2018-01-23

Abstract

A method and apparatus configured to cause a position of a mobile tag to be determined using a first positioning mode; detect that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold; in response thereto, cause a calculation relating to the position of the mobile tag using a second positioning mode to be performed; detect that a mobile tag has entered an area defined by an inner positioning geofence; in response thereto, switch from the first positioning mode to the second positioning mode; and cause the position of the mobile tag to be determined using the second positioning mode.

Description

Positioning method Field

Embodiments of the invention relate to positioning methods.

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. Bluetooth Low Energy (BTLE) technology has been proposed to be used in indoor positioning systems for tracking devices. Such systems involve the use of High Accuracy Indoor Positioning (HAIP) which places requirements on hardware infrastructure such as the need for multiple array antennas. Therefore this makes for a simpler and more efficient system that is easier to implement using BTLE hardware technology that is already available in the market. The principles of BTLE are described in the art.

High-Accuracy Indoor Positioning (HAIP) tracks the position of Bluetooth LE tags using ceiling-installed locators which perform Angle-of- Arrival measurement on the signal emitted 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.

Summary

In a first aspect, this specification describes a method comprising causing a position of a mobile tag to be determined using a first positioning mode; detecting that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold; in response thereto, causing a calculation relating to the position of the mobile tag using a second positioning mode to be performed; detecting that a mobile tag has entered an area defined by an inner positioning geofence; in response thereto, switching from the first positioning mode to the second positioning mode; and causing the position of the mobile tag to be determined using the second positioning mode.

The method may further comprise switching from a first user interface mode related to the first positioning mode to a second user interface mode related to the second positioning mode.

Switching from the first user interface mode to the second user interface mode may be in response to detecting that the mobile tag has entered an area defined by an inner user interface geofence.

The inner user interface geofence may be nested within the inner positioning geofence.

Detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold may cause activation of the inner positioning geofence and an outer positioning geofence.

Detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold may cause activation of the inner user interface geofence and an outer user interface geofence.

The method may further comprise detecting that the mobile tag has left an area defined by an outer positioning geofence and, in response thereto, switching to the first positioning mode.

The method may further comprise detecting, subsequent to switching to the first positioning mode, that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value and, in response thereto, disabling calculations relating to the second positioning mode.

The method may further comprise detecting that the mobile tag has left an area defined by an outer user interface geofence and, in response thereto, switching from a second user interface mode related to the second positioning mode to a first user interface mode related to the first positioning mode. The method may further comprise displaying a position on a user interface using the first positioning mode based on a calculation using the second positioning mode.

The method may further comprise determining the position of the mobile tag using the second positioning mode, detecting that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value, detecting that a predetermined time period has elapsed, and in response causing the position of the mobile tag to be determined using the first positioning mode.

The inner positioning geofence may be nested within the outer positioning geofence.

The first mode may be configured to determine a position based on the signal strength of a received packet.

The second mode may be configured to determine a position based on the angle of arrival of a received packet.

The mobile tag may be contained within one of: a key fob, a smartphone, a tablet.

The mobile tag may be BLE-capable.

The method may further comprise transmitting location information in accordance with the first or second positioning modes to a user device.

The mobile tag may be comprised within the user device.

In a second aspect, this specification describes a computer program comprising instructions that, when executed by a computing apparatus, cause the computing apparatus to perform the method according to the first aspect.

In a third 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: cause a position of a mobile tag to be determined using a first positioning mode; detect that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold; in response thereto, cause a calculation relating to the position of the mobile tag using a second positioning mode to be performed; detect that a mobile tag has entered an area defined by an inner positioning geofence; in response thereto, switch from the first positioning mode to the second positioning mode; and cause the position of the mobile tag to be determined using the second positioning mode.

In a fourth 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: causing a position of a mobile tag to be determined using a first positioning mode; detecting that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold; in response thereto, causing a calculation relating to the position of the mobile tag using a second positioning mode to be performed; detecting that a mobile tag has entered an area defined by an inner positioning geofence; in response thereto, switching from the first positioning mode to the second positioning mode; and causing the position of the mobile tag to be determined using the second positioning mode.

In a fourth aspect, this specification describes an apparatus comprising means for causing a position of a mobile tag to be determined using a first positioning mode; means for detecting that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold; means for, in response thereto, causing a calculation relating to the position of the mobile tag using a second positioning mode to be performed; means for detecting that a mobile tag has entered an area defined by an inner positioning geofence; means for, in response thereto, switching from the first positioning mode to the second positioning mode; and means for causing the position of the mobile tag to be determined using the second positioning mode. 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 2A is a schematic plane view of the indoor environment;

Figure 2B is a state diagram illustrating an embodiment of the invention; Figure 3 is a flow chart illustrating steps taken when a mobile tag enters a HAIP area;

Figure 4 is a flow chart illustrating steps taken when a mobile tag leaves a HAIP area;

Figure 5 is a state diagram illustrating an embodiment of the invention wherein a weak signal is detected;

Figure 6A is a schematic plane view of the indoor environment having user interface geofences; Figure 6B is a state diagram illustrating an embodiment of the invention wherein a mobile tag enters and leaves the user interface geofences of Figure 6A;

Figure 7 is a schematic block diagram of an HAIP locator; Figure 8 is a schematic block diagram of a COIP locator;

Figure 9 is a schematic block diagram of a mobile tag; and

Figure 10 shows a storage means.

Detailed Description

Embodiments of the invention provide for effective handover between two positioning modes. The first positioning mode may be a low intensity indoor positioning mode which uses received RSSI values to determine the position of a mobile tag. The first positioning mode may also make use of Time of Flight (ToF) calculations. The second, more power-intensive positioning mode, may use angle-of-arrival calculations. The handover between the two modes is managed efficiently so that power consumption can be optimised. Furthermore, the handovers are arranged so that they minimise disruption to a user interface (UI), for example a map shown on a display device. The first positioning mode may be termed a cost-optimised indoor positioning (COIP) mode. The second positioning mode may be termed a high accuracy indoor positioning (HAIP) mode. COIP locators and HAIP locators may be provided in an indoor environment which are positioning devices that operate in COIP mode and HAIP mode respectively.

Since the inside of buildings is not free space, the accuracy of indoor positioning systems may be significantly impacted by reflection and absorption from walls. Non- stationary objects such as doors, furniture, and people can pose an even greater problem, as they can affect the signal strength in dynamic, unpredictable ways.

Therefore, 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. The processing steps required to determine whether the HAIP mode should be used consume a similar level of computing resources compared to the resources required to perform the HAIP positioning itself. From the HAIP calculation, tag coordinates are obtained (the accuracy of which depends on how close the mobile tag is to the HAIP area) which can be used to evaluate whether the tag is within the HAIP area. However, it is desirable not to perform these calculations unnecessarily as they are

computationally intensive.

When displaying a position on a map using COIP mode, the tag location is displayed as a logical location (e.g. "room 123"). When displaying a position on a map using HAIP mode, the tag location is displayed as coordinates (e.g. x:i23, y:456). It is therefore desirable to prevent situations where a mobile tag's location calculation constantly switches between HAIP and COIP modes. The representation of the location can look very different on a map for COIP and for HAIP, so constantly switching between the two modes would cause the user interface to stutter.

Furthermore, it is also desirable not to constantly switch HAIP calculation on and off for a mobile tag, since that requires reconfiguration of the positioning system which is not instantaneous. As stated above, COIP locators measure signal strength and deliver only approximate location information (for example, at room-level) rather than using the angle of arrival methods used in HAIP locators. COIP methods can be combined with HAIP methods so that areas where high accuracy positioning is needed are equipped with HAIP locators and other areas are equipped with COIP locators. Embodiments use first and second signal strength thresholds to determine whether HAIP calculation is performed or not. The determination of whether to use HAIP calculation is dependent on whether a mobile tag is approaching an HAIP area or moving away from an HAIP area. Embodiments additionally have two nested geofences which determine whether the tag location is determined and provided to a user using HAIP mode or COIP mode. The determination of whether to use HAIP or COIP is also dependent on whether a mobile tag is approaching an HAIP area or moving away from an HAIP area.

As such, embodiments of the invention make use of hysteresis. The handover from the COIP mode to the HAIP mode is performed using a distinct signal strength (RSSI) threshold value and a distinct geofence from the RSSI threshold value and geofence that are used when handing over from HAIP mode to COIP mode.

Figure 1 shows a system 100 used to determine the location of a mobile tag in accordance with embodiments of the invention. The system 100 comprises positioning devices in fixed positions. These positioning devices include HAIP locators 3O1, 3Ο2, 3Ο3, 3Ο4 and COIP locators 4O1, 40₂. The HAIP locators 30 and COIP locators 40 are controlled by a controller 50 comprising processor circuitry 51 and non-volatile memory 52. The controller 50 may be a server. The non-volatile memory 52 has code 52a stored therein to allow the controller 50 to perform its functionality. The controller 50 also comprises volatile memory 53. Together, the non-volatile memory 52 and volatile memory 53 form a storage device 54. Whilst in Figure 1, the controller is shown proximate the HAIP locators 30 and COIP locators 40, it should be borne in mind that the controller 50 may be located remotely.

A user 1 may carry a BTLE mobile tag 10 into an indoor environment 20 in which the HAIP locators 30 and COIP locators 40 are located. The BTLE mobile tag 10 may be part of a smartphone, a key fob, a PDA and so forth. Example indoor environments include warehouses, hospitals, shopping malls and so forth. Some of the BTLE fixed tags are HAIP locators 30 located in an HAIP area 200 shown in Figure 2A. The HAIP area 200 is the area in which HAIP positioning is used. The area in the indoor environment 20 outside the HAIP area 200 may be termed the COIP area. The remaining BTLE fixed tags are COIP locators 40 that are located in the COIP area. Each of the HAIP locators 30 and the COIP locators 40 comprises processor circuitry, a storage medium and computer code stored therein that allows the functionality of the HAIP locators and COIP locators to be carried out.

In embodiments of the invention, when a mobile tag approaches a HAIP positioning area 200, both HAIP locators 30 and COIP locators 40 receive the radio signal transmitted by the mobile tag 10. The controller 50 of the positioning system 100 is configured to select when to switch from COIP positioning to HAIP positioning and vice versa. Figure 3 is a flow chart showing the various steps performed by the controller 50 of a positioning system in accordance with various embodiments of the invention in order to determine the position of a mobile tag as the mobile tag approaches an HAIP positioning area 200. During the following description reference is also made to Figure 2 to illustrate the operation of the various steps.

The process begins at step 3.1.

Step 3.2 is an ongoing step. The positioning system is operating in COIP mode. COIP mode may be thought of as the default mode for the positioning system. In other words, the system operates in COIP mode unless HAIP is activated. This corresponds to the position I shown in Figures 2A and 2B.

At position I, no HAIP calculations are performed. The position of the mobile tag 10 may be displayed on a user interface (such as a map application) as a logical position, for example the room in which the mobile tag 10 is located may be highlighted on the map.

The mobile tag 10 is in an area that is monitored by the system using the COIP mode. Each of the COIP locators is provided with an antenna, a processor and memory. Each COIP locator is configured to measure the RSSI of the packet and relay this information to the controller 50. The controller 50 can collate RSSI information relating to each packet from each COIP locator having a known position. From this information, the controller is able to determine the position of the mobile tag 10 in accordance with the COIP mode. The mobile tag 10 transmits packets which are detected by COIP locators and HAIP locators that are within range of the mobile tag 10, at step 3.3. The transmission of the packets by the mobile tag 10 is performed periodically. Each of the packets contains a tag identifier, and a transmit timestamp. As shown in Figures 2A and 2B, the user carrying the mobile tag 10 approaches an area 200 having HAIP locators 30, each of which uses angle of arrival measurements to determine mobile tag positions. As the mobile tag approaches the HAIP positioning area, packets transmitted by the mobile tag 10 are detected but the signal strength of these packets, as detected by the HAIP locators is very weak at first. This may correspond to the position II shown in Figure 2. At position II, no HAIP calculations are performed. Again, the position of the mobile tag 10 may be displayed on a user interface (such as a map application) as a logical position, for example the room in which the mobile tag 10 is located may be highlighted on the map. At this stage, the packets received from the mobile tag 10 are used to perform positioning according to the COIP mode. That is, the RSSI data that are measured at various COIP locators are used to determine the position of the mobile tag 10 as shown on a user interface (UI) of a user's mobile device such as a smartphone. As the mobile tag 10 approaches the HAIP positioning area 200, the RSSI values from the periodically transmitted packets detected at the HAIP locators 30 increase in strength. The controller 50 determines that the RSSI value at one or more of the HAIP locators 30 increases above a first threshold SSi at step 3.3. In response, HAIP calculation is switched on for the mobile tag 10 and the controller 50 activates nested outer and inner geofences GFi, GF2 around the HAIP positioning area 200, at step 3.4.

This may correspond to a mobile tag 10 being located at the position III as shown in Figures 2A and 2B. At this stage, COIP is still performed and the position of the mobile tag that may be displayed to a user on a user interface is still the position determined using COIP. The HAIP calculation is configured by the controller 50 to operate as a background operation.

As the mobile tag 10 approaches the HAIP positioning area, it first enters the outer geofence GFi, as shown in position Γν in Figures 2A and 2B. At this point, the positioning is carried out in COIP mode. The determination that the mobile tag 10 has entered the outer geofence GFi is performed using the HAIP calculation.

The controller 50 detects that the mobile tag 10 has entered the inner geofence GF2 at step 3.5. This corresponds to the position V shown in Figures 2A and 2B.

In response to the mobile tag 10 entering the inner geofence GF2, the controller 50 switches the mobile tag 10 to HAIP positioning at step 3.6. At this stage, the position shown on a user interface is displayed in accordance with HAIP mode. The

determination that the mobile tag 10 has entered the inner geofence GF2 is also performed using the HAIP calculation.

Figure 4 is a flow chart showing the various steps performed by the controller 50 of the positioning system in accordance with various embodiments of the invention in order to determine the position of a mobile tag 10 as the mobile tag 10 moves away from the HAIP positioning area 200. During the following description reference is also made to Figures 2A and 2B to illustrate the operation of the various steps. In general, once the mobile tag 10 moves away from the HAIP positioning area 200, HAIP positioning and HAIP calculation are deactivated.

The process starts at step 4.1. The mobile tag 10 may be located at the position V shown in Figures 2A and 2B. At step 4.2, packets received at the HAIP locators 30 are processed by the controller 50 using HAIP mode. The periodic packets are processed in the HAIP positioning mode as the mobile tag 10 moves inside the inner geofenced area. The periodic packets are also processed in the HAIP positioning mode as the mobile tag 10 if the mobile tag 10 moves outside the inner geofenced area but remains inside the outer geofenced area, as represented by position VI in Figures 2A and 2B. Thus, the position of the mobile tag 10 may be displayed on a map user interface as a coordinate position. At step 4.3, the positioning system 50 detects that the mobile tag 10 has left the outer geofence GFi. This is represented by position VII in Figures 2A and 2B which is equivalent to position III. In response, at step 4.4, the positioning system switches the positioning mode for the mobile tag 10 to COIP positioning mode. The position displayed on a UI is shown using the COIP positioning mode instead of the HAIP mode. However, HAIP calculations continue to be performed by the positioning system for the mobile tag 10 as a background operation.

As the mobile tag 10 moves further away from the HAIP positioning area 200, the RSSI values of the periodically transmitted packets, as measured by the HAIP locators 30, decrease. Firstly, the received RSSI values drop below the first threshold SSi. At this point, HAIP calculations for the mobile tag 10 are continued. This is represented by position VIII in Figures 2A and 2B.

At step 4.5, the received RSSI values drop below a second threshold SS2 which is less than the first threshold SSi. Once the signal strength drops below the second threshold SS2, HAIP calculation is switched off for the tag, at step 4.6. This may correspond to the position IX shown in Figures 2A and 2B which is equivalent to position I. The process ends at step 4.7.

Therefore, it is apparent from the discussion above that the hysteresis arises from using a first threshold SSi for enabling HAIP calculations and a second, distinct, threshold SS2 for disabling HAIP calculations. Furthermore, an inner geofence GF2 is used to switch from COIP positioning mode to HAIP positioning mode, whilst a distinct outer geofence GFi is used to switch from HAIP positioning mode to COIP positioning mode.

Once the controller 50 has determined the location of the mobile tag 10 in either COIP or HAIP mode, the location information may be transmitted as a packet to a user device. The user device may be a mobile device in which the mobile tag 10 is itself contained. Alternatively, the user device may be a desktop computer, laptop or any other device so that a user can track the position of the mobile tag. Figure 5 is a flow chart illustrating steps taken by the controller 50 if the RSSI value drops below the threshold SS2 while the location of the mobile tag 10 is still being provided in HAIP mode. The RSSI value may drop below the threshold SS2 if an object blocks the signal. Positions I to IX are shown equivalent to positions I to IX as shown in Figure 2B. If the RSSI value drops below the threshold SS2 while the mobile tag is inside the inner geofence GF2, as represented by position V, or is outside the inner geofence GF2 and inside the outer geofence GFi, as represented by position VI, then the controller 50 makes a weak signal determination. The last known position of the mobile tag 10 may be displayed to the user on a user interface. If the RSSI recovers and increases above threshold SS2, then the process returns to the state shown in position V if the position is determined to be inside the inner geofence GF2 or to the state shown in position VI if the position is determined to be inside the outer geofence GFi but outside the inner geofence GF2. If the RSSI value drops below the threshold SS2 while the mobile tag is inside the outer geofence GFi and outside the inner geofence GF2 and the positioning is in COIP mode (as represented by position IV), then HAIP calculations are switched off and the positioning system is reset to the position I shown in Figure 5. If the RSSI signal does not recover and increase above the threshold SS2 within a predetermined time limit, then the positioning system is reset and the mobile tag location is switched to COIP mode and the user interface is updated to show the location as a logical position rather than as a coordinate position. Furthermore, HAIP calculations may be ceased.

In order to prevent transient signal blockage, whereby the signal is temporarily blocked (e.g. by a person walking between the mobile tag 10 and the positioning device), from having too much of an effect, the signal strength used by the controller 50 may, for example, be an average or median value of several measurements. As explained above in relation to Figure 5, it may be required that the RSSI value remains below the second threshold SS2 for a certain time before either HAIP positioning or HAIP calculations are ceased.

In some embodiments of the invention, the geofences used to switch between HAIP and COIP positioning are distinct from the geofences used to switch between user interface modes. This may allow use of hysteresis to provide a smooth transfer between user interface modes which may be different from the capabilities of different positioning modes.

For example, while the position may be determined using HAIP positioning mode, the position may be displayed on the user interface as a logical position (for example, a room number) in accordance with the COIP user interface mode.

Figures 6A and 6B illustrate a configuration where separate UI geofences are provided. Referring to Figure 6A, an inner UI geofence may be nested within the inner geofence GF2. The outer UI geofence is the same as the outer positioning geofence GFi in this example.

Figure 6B is an example state diagram showing how UI positioning is switched in a configuration whereby a mobile tag 10 moves between the various geofences. To simplify the explanation, the description of enabling and disabling HAIP calculations has not been repeated.

At position I, the mobile tag 10 is outside the outer geofence GFi. At this point, no HAIP calculations are performed, COIP positioning mode is employed and the mobile tag position is displayed using COIP UI mode.

At position II-A, the mobile tag 10 enters the outer positioning geofence GFi which is identical to outer UI geofence UIGFi. Prior to entering GF1/UIGF1, the RSSI value may increase above SSi, leading to HAIP calculations being enabled. However, COIP positioning mode is used and the mobile tag position is displayed using COIP UI mode.

At position II-B, the mobile tag 10 enters the inner positioning geofence GFi. The system switches to HAIP positioning mode. However, the UI displays the position using COIP mode.

At position III, the mobile tag 10 enters inner UI geofence UIGF2. At this point, the UI switches to displaying the position using an HAIP UI mode. For example, the position may now be presented to the user as a coordinate instead of a room number.

At position IV, the mobile tag 10 leaves inner UI geofence UIGF2. The UI continues to display the position in HAIP UI display mode. At position V, the mobile tag 10 leaves outer UI geofence UIGFi and outer positioning geofence GFi. The system switches both the UI and positioning modes to COIP mode since GFi and UIGFi are identical.

As the RSSI drops below threshold SS2, HAIP calculations may be disabled.

Providing UI geofences that are separate from the positioning geofences allows the UI to switch between modes more conservatively than if no separate UI geofences were provided. This configuration helps to reduce UI stutter, whereby the UI switches between modes at a frequency which is uncomfortable or inconvenient for the user.

In alternative embodiments, instead of using separate UI geofences and positioning geofences, a timer may be used so that UI mode is switched to HAIP once HAIP positioning has been used for a certain time.

For example, when a mobile tag enters the HAIP positioning area, the system may start to calculate the accurate position earlier than the user interface mode is changed. In other words, the accurate position is presented to the user only after a certain confidence level for positioning quality has been achieved.

An advantage of embodiments of the invention is that it is possible to switch efficiently between HAIP mode and COIP mode since HAIP calculation is only performed when a mobile tag is near to the HAIP area 200. Use of hysteresis prevents situations where HAIP calculation is being switched on and off at an unwanted frequency for a mobile tag, or where the positioning mode switches between HAIP positioning and COIP positioning at an unwanted frequency.

Furthermore, overly frequent switching between UI modes can be prevented. Figure 7 is a simplified schematic of an example of the HAIP locator 30 of Figures 1 and 2. The HAIP locator 30 comprises a controller 31, a transceiver 32 and an array of antennas 33. The array 33 of antennas comprises a plurality of antenna elements 33A, 33B) 33C which receive the packets and allow for angle-of-arrival information to be determined. The controller 31 may be of any suitable construction but, in this example, the controller 31 comprises processing circuitry 34 and a storage device 35. The processing circuitry 34 is configured, under the control of computer-readable code 36A stored on the storage device 35, to control the operation of the HAIP locator 30. The storage device 35 comprises a non-volatile memory 36 on which is stored the computer-readable code 36A. The storage device 35 also comprises a volatile memory 37·

Each of the plurality of antenna elements 33A, 33B, 33C connected to a switch (not shown), which is controllable by the processing circuitry 34 operating under the control of computer readable code stored in the storage device 35. The switch is controlled so that only one of the antenna elements 33A, 33B, 33C is connected to the transceiver 32 at any one time.

Figure 8 is a simplified schematic of an example of the COIP locator 40 of Figures 1 and 2. The COIP locator 40 comprises a controller 41, a transceiver 42 and an antenna 43. The controller 41 may be of any suitable construction but, in this example, the controller 41 comprises processing circuitry 44 and a storage device 45. The processing circuitry 44 is configured, under the control of computer-readable code 46A stored on the storage device 45, to control the operation of the COIP locator 40. The storage device 45 comprises a non-volatile memory 46 on which is stored the computer- readable code 46A. The storage device 45 also comprises a volatile memory 47.

Figure 9 is a simplified schematic of an example of the mobile tag 10 of Figure 1. The mobile tag 10 comprises a controller 11, a transceiver 12 and an antenna 13. The controller 11 is configured to control the transceiver 12 to transmit via the antenna 13 positioning packets periodically. In some examples in which the mobile tag 10 is in its most simple form, the transceiver 12 may be replaced by a transmitter such that the mobile tag 10 does not have receiving capabilities.

The controller 11 may be of any suitable construction but, in this example, the controller 11 comprises processing circuitry 14 and a storage device 15. The processing circuitry 14 is configured, under the control of computer-readable code 16A stored on the storage device 15, to control the operation of the mobile tag 10. The storage device 15 comprises a non-volatile memory 16 on which is stored the computer-readable code 16A. The storage device 15 also comprises a volatile memory 17. The mobile tag 10 additionally comprises a power source (not shown) such as a battery. In other examples, the mobile tag 10 receives power from an external source. The mobile tag 10 is in some specific examples configured to transmit signals via the Bluetooth Low Energy protocol. That is to say the mobile tag 10 is able to operate in accordance with the BLE standard, currently at version 4.0. Put another way, the mobile tag 10 is "BLE-capable".

The computer readable instructions 52A, 36A, 46A, 16A may be pre-programmed into the apparatuses 50, 30, 40, 10. Alternatively, the computer readable instructions 52A, 36A, 46A, 16A may arrive at the apparatus 50, 30, 40, 10 via an electromagnetic carrier signal or may be copied from a physical entity 1000 (see Figure 10) such as a computer program product, a memory device or a record medium such as a CD-ROM or DVD. The computer readable instructions 52A, 36A, 46A, 16A may provide the logic and routines that enables the devices/apparatuses 50, 30, 40, 10 to perform the

functionality described above.

Various terms used above will now be described in more detail. HAIP calculation

Performing an HAIP calculation refers to performing the calculations needed to obtain the coordinates of the tag. However, the result of the calculation may be that the tag is too far away from the HAIP locators for accurate positioning (i.e. the result returns coordinates that may be inaccurate and so positioning may still be performed using COIP. The HAIP calculations are based on angle of arrival (AoA) data obtained from the packets. The HAIP locators 30 each comprise an array of antennas to obtain the AoA data. Signals/positioning packets transmitted by the mobile tags 10 may be according to the High Accuracy Indoor Positioning (HAIP) solution, for example as described at http: //www.in-location-alliance.com.

HAIP positioning

HAIP positioning means that the system delivers the location of a tag using coordinates (as opposed to the logical locations, such as room names, that COIP delivers). The position determined by the HAIP calculations is used as the mobile tag position.

However, the UI may still display the position to the user as a logical position (such as a room number) in accordance with a COIP mode. HAIP user interface

Using HAIP positioning in the UI means that the UI displays the location of a tag using coordinates rather than a logical location such as a room number. For example, when COIP positioning is used to locate a tag, the entire room might be highlighted on the map, whereas when HAIP positioning is used, a small blinking dot might be shown at the coordinates of the tag.

Hence, a situation may arise whereby an HAIP calculation is performed, but because the tag is not yet close enough to provide an accurate position, COIP positioning is still used, i.e. the tag location is delivered as a logical location (e.g. a room).

The COIP position may, in this case, be calculated based on either the inaccurate coordinates that are used to determine a logical location or based on RSSI

measurements as determined by the HAIP locators 30.

COIP mode

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.

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.

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

causing a position of a mobile tag to be determined using a first positioning mode;

detecting that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold;

in response thereto, causing a calculation relating to the position of the mobile tag using a second positioning mode to be performed;

detecting that a mobile tag has entered an area defined by an inner positioning geofence;

in response thereto, switching from the first positioning mode to the second positioning mode; and

causing the position of the mobile tag to be determined using the second positioning mode.

2. The method of claim l, further comprising switching from a first user interface mode related to the first positioning mode to a second user interface mode related to the second positioning mode.

3. The method of claim 2, wherein switching from the first user interface mode to the second user interface mode is in response to detecting that the mobile tag has entered an area defined by an inner user interface geofence.

4. The method of claim 3, wherein the inner user interface geofence is nested within the inner positioning geofence.

5. The method of any preceding claim, wherein detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold causes activation of the inner positioning geofence and an outer positioning geofence.

6. The method of claim 5, wherein detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold causes activation of the inner user interface geofence and an outer user interface geofence.

7. The method of any preceding claim, further comprising detecting that the mobile tag has left an area defined by an outer positioning geofence and, in response thereto, switching to the first positioning mode.

8. The method of claim 7, further comprising detecting, subsequent to switching to the first positioning mode, that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value and, in response thereto, disabling calculations relating to the second positioning mode.

9. The method of any preceding claim, further comprising detecting that the mobile tag has left an area defined by an outer user interface geofence and, in response thereto, switching from a second user interface mode related to the second positioning mode to a first user interface mode related to the first positioning mode.

10. The method of any preceding claim, further comprising displaying a position on a user interface using the first positioning mode based on a calculation using the second positioning mode.

11. The method of any preceding claim, further comprising determining the position of the mobile tag using the second positioning mode, detecting that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value, detecting that a predetermined time period has elapsed, and in response causing the position of the mobile tag to be determined using the first positioning mode.

12. The method of any preceding claim, wherein the inner positioning geofence is nested within the outer positioning geofence.

13. The method of any preceding claim, wherein the first mode is configured to determine a position based on the signal strength of a received packet.

14. The method of any preceding claim, wherein the second mode is configured to determine a position based on the angle of arrival of a received packet.

15. The method of any preceding claim, wherein the mobile tag is contained within one of: a key fob, a smartphone, a tablet.

16. The method of any preceding claim, wherein the mobile tag is BLE-capable.

17. The method of any preceding claim, further comprising transmitting location information in accordance with the first or second positioning modes to a user device.

18. The method of claim 11, wherein the mobile tag is comprised within the user device.

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

20. 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:

cause a position of a mobile tag to be determined using a first positioning mode; detect that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold;

in response thereto, cause a calculation relating to the position of the mobile tag using a second positioning mode to be performed;

detect that a mobile tag has entered an area defined by an inner positioning geofence;

in response thereto, switch from the first positioning mode to the second positioning mode; and

cause the position of the mobile tag to be determined using the second positioning mode.

21. The apparatus of claim 20, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to switch from a first user interface mode related to the first positioning mode to a second user interface mode related to the second positioning mode.

22. The apparatus of claim 21, wherein switching from the first user interface mode to the second user interface mode is in response to detecting that the mobile tag has entered an area defined by an inner user interface geofence.

23. The apparatus of claim 22, wherein the area defined by an inner user interface geofence is nested within the area defined by an inner positioning geofence.

24. The apparatus of any preceding claim, wherein detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold causes activation of the inner positioning geofence and an outer positioning geofence.

25. The apparatus of claim 24, wherein detecting that the received signal strength indicator value exceeds a first signal strength indicator threshold causes activation of the inner user interface geofence and an outer user interface geofence.

26. The apparatus of any preceding claim, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to detect that the mobile tag has left an area defined by an outer positioning geofence and, in response thereto, switching to the first positioning mode.

27. The apparatus of claim 26, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to detect, subsequent to switching to the first positioning mode, that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value and, in response thereto, disabling calculations relating to the second positioning mode.

28. The apparatus of any preceding claim, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to detect that the mobile tag has left an area defined by an outer user interface geofence and, in response thereto, to switch from a second user interface mode related to the second positioning mode to a first user interface mode related to the first positioning mode.

29. The apparatus of any preceding claim, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to display a position on a user interface using the first positioning mode based on a calculation using the second positioning mode.

30. The apparatus of any preceding claim, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to determine the position of the mobile tag using the second positioning mode, to detect that the received signal strength indicator value is below a second threshold value, wherein the second threshold value is lower than the first threshold value, to detect that a predetermined time period has elapsed, and in response to cause the position of the mobile tag to be determined using the first positioning mode.

31. The apparatus of any preceding claim, wherein the inner positioning geofence is nested within the outer positioning geofence.

32. The apparatus of any preceding claim, wherein the first mode is configured to determine a position based on the signal strength of a received packet.

33. The apparatus of any preceding claim, wherein the second mode is configured to determine a position based on the angle of arrival of a received packet.

34. The apparatus of any preceding claim, wherein the mobile tag is contained within one of: a key fob, a smartphone, a tablet.

35. The apparatus of any preceding claim, wherein the mobile tag is BLE-capable.

36. The apparatus of any preceding claim, the computer-readable instructions when executed by the at least one processor causing the apparatus at least to transmit location information in accordance with the first or second positioning modes to a user device.

37. The apparatus of claim 11, wherein the mobile tag is comprised within the user device.

38. A computer-readable medium having computer-readable code stored thereon, the computer-readable code, when executed by at least one processor, causing performance of: causing a position of a mobile tag to be determined using a first positioning mode;

39. Apparatus comprising:

means for causing a position of a mobile tag to be determined using a first positioning mode;

means for detecting that a received signal strength indicator value received from the mobile tag exceeds a first signal strength indicator threshold;

means for, in response thereto, causing a calculation relating to the position of the mobile tag using a second positioning mode to be performed;

means for detecting that a mobile tag has entered an area defined by an inner positioning geofence;

means for, in response thereto, switching from the first positioning mode to the second positioning mode; and

means for causing the position of the mobile tag to be determined using the second positioning mode.