Field of the invention:
This invention relates generally to a system and method for locating, tracking and monitoring the movements of mobile devices or beings and, more particularly, to a system for determining the position of a moving body indoors using Bluetooth technology.
Bacl(ground of tiie invention:
All location aware applications such as navigators and map applications require Indoor tracking to monitor tiie movements of mobile devices or beings, indoors. Most of the location aware applications available today use the absolute position which is normally received from GPS hardware. Due to the lack of visibility of GPS satellites, indoor tracking using this technology poses many limitations. GPS receivers inside a buikiing in urban area may suffer from multipath errors and weak signals from reflective coatings, tail buildings and other infrastructures. As a result, GPS signals are typbaily weaker in indoor environments and with such weakened signals, GPS receivers have difficulty receiving GPS signals and calculating accurate position Information.
Prior Art
A few indoor tracking systems have previously been described.
US Patent No. 2009/0046005 by Namineni; Pavan K. ; et al. discloses a wireless mobile indoor/outdoor tracking system which is designed to tirade the absolute position of all nodes in a network indoors and outdoors. The system uses GPS positioning when a signal is available and RF ranging when it is unavailable. When indoors, a minimum of three network nodes must receive a GPS signal to detennine absolute position. A mesh network is used to make the system mobile and to create an avenue for data to be transmitted to a remote base station.
The following table consolidates various indoor tracking technok)gie8, its advantages and disadvantages.

The advantages of this new solution are therefore apparent in the tabular column illustrated above.
Further, most of the conventional Bluetooth stacks require user confimnation before connectivity. In this new technology, the location information is impregnate in the Bluetooth device name itself so that no explicit connection is required for accessing the infonnation. For the Bluetooth device, the location infonnation is static and is not required to be changed except during the installation.
Objectives of the Invention:
The object of the invention is to provide the absolute position of mobile devices or beings indoors.
Anotiier object of the invention is to obtain the absolute position infonnation as ttie device name during the Biuetootii device discovery procedure.
Yet another object of the invention is to enable a user of the device to use the same location aware application which uses QPS outdoor.
Yet another more object of the invention is to allow the user to use location aware application indoor without any modification of existing Bluetooth enabled mobile devices.
Anotiier object of the invention is to allow the user to use location aware application indoor without any modification In the firmware of GPS.
One more object of the invention is to enable the devices equipped with Bluetooth and GPS hardware to use Indoor and Outdoor tracking seamlessly.

Summary of the Invention:
The system in accordance with this invention envisages means for indoor tracking using Bluetooth technology.
According to one embodiment of the invention there Is provided an etectronic device comprising: a radio transceiver with short range wireless communication technology such as Bluetooth, Zigbee etc. for receiving the absolute position request message and for responding with the absolute position.
According to another embodiment of the invention there Is provided a computer program comprising computer instructions for enabling an etectronic transceiver to respond to a received position request message by transmitting position information. The computer program may be embodied on a computer readable medium or carrier or memory.
According to another embodiment of the invention there Is provided a metiiod of transferring data from an electronic device to another electronic device, wherein the position request is received by the electronic device and in response, transmits data comprising the absolute position infonnatlon.
The electronic device may further comprise a programmable memory for storing the absolute position and a means for reading the data from the memory for inclusion in a position response message.
According to another embodiment of the invention, there is provided an electronic device comprising: a radio transceiver with short range wireless communication technology such as Bluetooth, Zigbee etc. for transferring a position request message and for receiving in reply a response message.

According to yet another embodiment of the invention, there is provided a computer program comprising computer program instructions enabling an electronic transceiver device to respond to a received position reply message.
The electronic device invokes a position aware application automatically or by a user selection with the absolute position information extracted fmn the position reply message.
The features and advantages of the present invention will become more apparent from the ensuing detailed description of the invention taken in conjunction with the accompanying drawings
Brief description of the drawings
Figure 1 is a diagram illustrating a plurality of fixed devices and mobile devices according to the present invention.
Figure 2 is a block diagram showing one embodiment of an electronic device which provides location infomiation.
Figure 3 is a block diagram showing one embodiment of a mobile device according to the present invention.
Figure 4 shows a sample format of a position reply message.
Figure 5 Is a flow chart of an electronic device which provides the location infomnation.
Figure 6 is a flow chart of an electronic device which receives the location information provided by an electronic device.
Detailed description of drawings:
Bluetooth wireless technology is an international open standard for allowing intelligent devices to communicate with each other through wireless, short range communicatk>n. Bluetooth is referred to as a frequency hopping spread spectrum (FHSS) radio system that operates in a 2.4 GHz unlicensed band. Bluet(K>th bw power transmission allows a

typical range of about 10 meters. This range can vary from about 1 meter to 100 meters depending as the amount of power used by the device for Bluetooth.
Fig 1 shows an arrangement of Bluetooth enabled electronic devices some of which may be mobile and some of which may be stationery. In this example, devices 101 A, 101B, 101C, 101D, 101E and 101F are within the range of mobile devices 102A, 102B, 102C. 102D,102Eand102F.
101A, 101B, 101C, 101D, 101E and 101F are fixed devices, in Fig 2, the device 101 comprises: a processor (201) and interface such as serial port, USB etc (204), a radio transceiver (202), a memory (203) and a power source (205). The processor (201) is connected to the interface (204) to accept the absolute position to be stored in the memory (203).
The processor (201) is connected to a radio transceiver (202) to receive position request message and to send position response message.
The processor (201) is connected to memory (203) to read and v/rite position information. The memory (203) is used for storing computer program instructions that control the operation of the electronic device (101).
The computer program instnictions (206) may store in the electronic device (101) via a physical entity such as a computer program product, a memory device or a recorded medium such as a CD-ROM or DVD.
The device (101) accepte the absolute position information via the interface (204) as shown in 701 in Fig 5.
The device (101) constructs the Bluetooth device name based on the absolute position. The device name is stored in the memory (203).

The fomiat of incorporating the absolute position is mutually understandable to the device (101) and (102).
Fig 3, shows a device 102 that is suitable to execute the locatbn aware applicatkm. The device 102 may be a portable mobile device. In this example, the devtee (102) comprises: a processor (301), a radio transceiver (302), a memory (303) and a power source (305).
The memory (303) is used for storing the data and locatton provkler stack (304). Location provider stack is a computer program consisting of computer instructions to extract the absolute position from the position reply message from the device (101). Also the location provider steck (304) may provide the extracted absolute position to one or more location aware applications optionally avaliable (not shown) in the electronic device (102).
As an example, when a user dials 911 from a mobile device equipped with the electronic device (102) in an indoor where the fixed devices (101) are located, the device (102) searches for the fixed devices (101), and requests for the position information. The electronic device (101) responds to the response request message with position response infomration. The kication provkJer steck (304) extracts the position from the position response infomnation. Then, a location aware application may send the position of the user to the control room as in the case of outdoor.
The electronic device (102) may have other communicatton channels for retrieving information for location aware applicatk>n8 other than position. The electronic device (102) may have other local datebases for retrieving informatkm for the locatbn aware application.
Fig 5 is a flow chart illustrating the operation of the eiectronk: device (101). Refening to the Fig 5, in step (708) electronic device (101) initializes as inquiry scan enable and page scan enable.

The electronic device (101) receives the akjsolute position information from the user through the interface (204) of the electronic device as shown in st^ 701.
In step 702, the electronic device (101) constructs the device name based on the absolute position supplied through the interface (204).
In step 703, the electronic device writes the device name into the memory (203) of the electronic device (101).
The electronic device (101) enters into inquiry scan substate and listens for inquiry requests from mobile devices (102).
Initiator device (102) discovers other devices with which the device can request for position request. In this example, the initiator device (102) is in Inquiry substate and repeatedly sends inquiry messages as shewn in step (801).
The device (101) that allows to be discovered sends the Bluetooth device address (BD_ADDR), Bluetooth dock information etc.
in step 704, when the electronic device (101) receives the inquiry request from other mobile devices (102), it sends inquiry response in step 705.
The device (102) collects the list of ail devices in the range and store in a memory (303). The device (102) sends Name request as shown in step (803) to the electronic device (101).
The electronic device (101) enters into page scan sub-state and listens for the name requests from mobile devices (102).
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When the electronic device (101) receives name requests from the electronic devices (102) as shown in step 706, the electronic device (101) sends Its local device name to the electronic device (102).
The electronic device (101) sends device name which consists of position Information as shown in the step (706) and (707).
The present invention does not restrict any particular format for the position reply message but it must be mutually known to the electronic device (101) and electronic device (102). As per the Bluetooth specification, the device name is a UTF-8 enaxied User-Friendly descriptive Name for the device with at most 248 octets, if the name contained in the parameter is shorter than 248 octets, the end of the name is indicated by a NULL octet (0x00), and the following octets to fill up 248 octets.
Fig 4 shows a sample position reply message (600) which consists of device ID (601), latitude component (602) and longitude component (603) of the absolute position. The total length of the message (600), which is the sum of the length of device ID (601), length of latitude component (602) and length of longitude component (603), must be less than or equal to 248 octets.
The device (102) receives the device name response from all devices 101A, 101B, 101C etc. as shown in step 804.
The device collects all name response and store in the memory (303) as shown in step 810. The device 102 extracts the absolute position infonnation from the name response message of each and every device 101 A, 101B, 101C, 101D, 101E and 101F by the location provider stack (304) as shown in step 808.
If only one electronic device (101) is in the range of electrons device (102), then the accuracy of the position determined by the device (102) is the range of radk) transmitter
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of the device (101) which varies from 1 meter to 100 meters depending on the power of transmission of the radio transceiver (202).
If more than one electronic device (101) is in the range of electronic device (102), the electronic device (102) receives more than one position information. The electronic device (102) may apply logic to select the position match based on the signal strength (RSSI) of each electronic device (101).
The absolute position information extracted from the name response message by the electronic device (102) with the help of location provider stack (304) may pass on to a location aware application.
The kx»tion Infomnation is impregnate in the Bluetooth device name itself so that no explicit connection is required for accessing the infonnation. In the electronic device (101), the location information is static and is not required to change except during the installation.
Security
Since the data infomfiation is in the Bluetooth name itself, any Bluetooth device can fake the location of the electronic device (101) by providing suitable k}cation incorporated in the Bluetooth name itself.
Therefore, encryption is done at the electronic device (101) with BD__ADDR (48 bits) along with in-built encryption key. The device (101) Is also made connectabie so that any mobile device can connect and verify its authenticity.
Power consumption
The mobile device has to do periodic inquiry for the nearest electronic device (101). This consumes almost 10 times more power than its standby mode. For example, average power consumed during discovery is 180mW while in standby it is only 20mW.
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The following paragraphs discloses three algorithms for power saving.
i) Adaptive algorithm
Adaptive discovery algorithm is suggested to preserve enei^y such that during stationery mode (if the mobile phone is lying on the table or the user is available within the proximity of one location for a long time) the algorithm discover in every 10 minutes (as per Bluetooth protocol 1.1 and above; eac^ discovery last for 10.24 seconds, odnsumes only 1.12 times more power than stand by) while moving unit (user is walking) discover in every 1 minute.
ii) On demand algorithm
On demand algorithm suggests the discovery of the electronic device (101) only if there is a requirement from the application layer. The request from ihe location manager will be captured by the Bluetooth service and perfonn the inquiry. It will take 10.24 seconds to find all Bluetooth devices nearby which is much less than tiie 40 second of wamn start of the GPS receiver. In "On demand algorithm", the total power consumptbn for the Bluetooth discovery will be very less.
iii) IVIotion Sensing Algorithm
This algorithm is applicable only for devices having acceierometers and the software detects the user's activity such as sitting/walking etc. During walking it discovers nearest Bluetooth devices in a fast rate while in stationary there is no discovery.
The motion sensing algorithm, as described above, is the best mode for power consumption.
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Caching of Bluetooth name
Nomr^ally Bluetooth name will be acquired during the additional inquiry process and to reduce the discovery time some host Bluetooth stacks cache the Bluetooth name against the BD_ADDR. If the device finds the same electronic device 101 (same BD_ ADDR) in another location (ie service person moves the electronic device 101 to a new place with the modified location information) Bluetooth stack may retum the old name (contains oki position infomiation) which is cached before.
Even though this is a rare scenark), the Bluetooth component in the device will inquire always for the name to avoid the cached device name.
Accuracy
This technology provides the absolute information of the mobile devices when the mobile device is within the range of the Bluetooth (ie CEP Is 10 meter). However the accuracy of location can be increased by triangulation technkiues if three or more electronic devices (101) are visible on the spot. In triangulation the position and RSSI (which is available In the FHS packet of inquiry response) will be manipulated from all three or more electronic devices (101) and derives the posWon using trianguiatton technique. Using this triangulation algorithm the accuracy can be increased to a fraction of meters.
There are a few algorithms explained below to increase the accuracy of nneasurement
Proximity algorithm
If more than one electronic device (101) is in the visibility, the mobile device can determine more accurate position by measuring the signal strength from each electronic device (101). The mobile device is more ctose to the electrons device (101) which shows more signal strength. Hence the nrK}bile devtee can approximately take its position as the fix.
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To get accurate results, all electronic devices (101) must have the same transmitting signal strength and assumed that no multipath reflection and obstacles in the measured area. Also this requires a minimum of two electronic devices (101) in the range of measuring mobile device.
Tiiangulation technique
If more than two electronic devices (101) are in the vislbitity, the mobile device can detemnine more accurate position by measuring the signal strength from each elec^nic device (101).
Trianguiation technique greatly depends on the signal path traversal indoor and may give inaccurate results due to multi-path reflection and obstacles. Therefore, conection factor is incorporated based on geometry of the indoor and incorporated along with the position itself. Hence, the mobile device can determine the conection to be applied in each and environment. As the trianguiation technique calculates the position infonnation of the mobile device based on the signals received from two or more electronic device (101), the position information received is more accurate and this technique is the best mode to obtain the most accurate position infonnation from two or more electronic devices (101).
The present invention is not entirely dependent on tiie algorithms for its woridng. It only serves as a tool to improve the accuracy of the location Information obtained and to reduce the consumption of power in the mobile device.
The essence of the invention is a system and method for Indoor tracking comprising: atleast one or more electronic devices fixed at one or nrare locations, the said electronic device comprising a radio transceiver for receiving a position request message from a mobile device to be tracked and for responding with a position reply message, wherein the saki position reply message comprises tl^ absolute positton.
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Therefore, the present invention, discloses an indoor tracking technology using Bluetooth which lets the user to use mobile/hand heki devk»s indoor and outdoor seamlessly without any modification in hardware or installed applteations and other software.
While considerable emphasis has been placed herein on the particular features of the system for indoor tracking, the improvisation with regards to It, it will be appreciated that various modifications can be made, and that many changes can be made in the prefen-ed embodiment without departing from the principles of the invention.. These and other modifications in the nature of the invention or the prefened embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We Claim
1. An indoor tracking system comprising: one or more electronic devices fixed at one or more locations, the said electronic device comprising a processor, a memory coupled to the processor for storing and retrieving position Infomiation, a radio transceiver connected to the processor for receiving a position request message from a mobile device to be tracked and for responding with a position reply message comprising the location infomiation which is then sent to locatton aware applications.
2. An electronic device as claimed in claim 1, wherein the radio transceiver worics in a short range un-licensed frequency band.
3. An electronic device as claimed in claim 1, wherein the position reply message comprises the absolute position.
4. An electronic device as claimed in claim 1, wherein the memory is also used for storing computer instructions executable by the processor that control the operation of the electronic device.
5. An electronic device as claimed in any of the preceding claims, ftirther comprising an interface to accept position infomiation.
6. An electronic device as claimed in any of the preceding claims, wherein the position infomiation is incorporated in the device name.
7. An electronic device as claimed in claim 1, comprising computer instructions for enabling an electronic transceiver to respond to a received position request message by transmitting a position reply message as its devk» name.

8. The system as claimed in claim 1, wherein the mobile device comprises a radio transceiver which transmits a position request message and receives one or more position response messages from the fixed electronic devices.
9. The system as claimed in claim 1, wherein the bluetooth component in the mobile device always inquires for the device name to avoid the cached device name.
10. The system as claimed in claim 1, wherein the mobile device extracts the position information from one or more position reply messages.
11. The system as claimed in claim 1, wherein the mobile device may apply logic to select the position match based on the signal strength of each fixed electronic device.
12. The system as claimed in claim 1, wherein the mobile device may apply logic to reduce the consumption of power depending on the steite or movements of the mobile device.
13. The system as claimed in claim 1, wherein the said nfK>bile device sends the absolute position information to location aware applications.
14. A method for indoor tracking comprising the steps of: transmitting a position request message by the mobile device to be tracked, receiving at the fixed electronic device the position request message and in response sending the position infonnation to the mobile device by transmitting a position reply message as its device name, extracting from the mobile device the position information from the position reply message and sending the absolute position infomnatlon to location aware applications.
15.A method as claimed in claim 14, wherein the said method comprises the act of incorporating the position infonnation in the device name of the fixed electronic device.

16.A method as claimed in claim 14, wherein the said method comprises the act of storing the position infomiation in a memory device and reading the position information from the said memory device included in ttie fixed elecb'onic device.
17.A method as claimed in claim 14, wherein the said method comprises the act of enabling an electronic transceiver to respond to a received position request message by transmitting a position reply message as its device name.
I i
18.A method as claimed in claim 14, wherein the said method comprises the act of selectively applying logic to Increase the accuracy of the position Infonnation received from more than one electronic device and based on the signal strength from each fixed electronic device.
19. A method as claimed in claim 14, wherein the said method comprises the act of
selectively applying logic to reduce the consumption of power depending on the
state or movements of the mobile device.
20. A system for indoor tracking substantially as described herein before with reference to the enclosed drawings.
21. A method for indoor tracking substantially as described herein before with reference to the enclosed drawings.