Logical floor determination for a wireless device using weighted AP received signal strengths

• US 8,089,371 B2
• Filed: 07/30/2008
• Issued: 01/03/2012
• Est. Priority Date: 07/30/2008
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Pandey, Santosh G.
• Primary Examiner(s): Bugg, George
• Assistant Examiner(s): Dorsey, Renee
• Application Number:
  US12/182,563
• Publication Number:
  US 20100026513A1
• Time in Patent Office: 1,252 Days
• Field of Search: None
• US Class Current: 340/825.36
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G08B 21/0247 System arrangements wherein the alarm criteria uses signal strength
• CPC Class Codes: G08B 21/0275 Electronic Article Surveillance [EAS] tag technology used for parent or child unit, e.g. same transmission technology, magnetic tag, RF tag, RFID

Abstract

An apparatus configured to acquire received signal strength intensities (RSSIs) for a wireless device from a plurality of access points (APs) located on a plurality logical floors. The apparatus is configured to determine which logical floor the wireless device is on by analyzing the RSSIs. The RSSIs for each floor are adjusted with an adjustment value and are selectively weighted with at least two different weight values, and the adjusted and weighted RSSIs for each floor are each summed. The floor with highest sum of adjusted or weighted RSSIs is determined to be the floor the wireless device is on. The logical floor is further determined by sorting the RSSIs for each floor and then weighting the sorted RSSIs with the different weight values. The sorted and weighted RSSIs for each floor are summed. The floor with highest sum of weighted sorted RSSIs is determined to be the floor the wireless device is on.

Claims

1. A wireless device locating apparatus, the apparatus comprising:

a communication interface configured to receive signal strength values including a first set of signal strength values for an associated wireless device detected at a first plurality of radio receivers disposed in a first region and a second set of signal strength values for the associated wireless device detected at a second plurality of radio receivers disposed in a second region; and

,

determination logic operatively connected with the communication interface and being configured to determine a region that the associated wireless device is located, the determination logic including;

a first weighting portion selectively weighting the signal strength values of the first set of signal strength values with at least two different weight values as a first set of weighted signal strength values, and selectively weighting the signal strength values of the second set of signal strength values with at least two different weight values as a second set of weighted signal strength values;

a first summing portion summing the first set of weighted signal strength values as a first weighted sum, and summing the second set of weighted signal strength values as a second weighted sum; and

,

an identifying portion identifying the region that the wireless device is located by a comparison of the first weighted sum with the second weighted sum.

2. An apparatus according to claim 1 wherein:

the determination logic includes a sorting portion selectively sorting the signal strength values of the first set of signal strength values as a first set of sorted signal strength values and sorting the signal strength values of the second set of signal strength values as a second set of sorted signal strength values; and

,

the first weighting portion is configured to selectively weight the signal strength values of the first and second sets of sorted signal strength values by applying, respectively, a first set of predetermined weights having at least two different weight values against the first set of sorted signal strength values as said first set of weighted signal strength values and a second set of predetermined weights having at least two different weight values against the second set of sorted signal strength values as said second set of weighted signal strength values.

3. An apparatus according to claim 2 wherein said determination logic further includes:

an adjusting portion adjusting the signal strength values of the first set of signal strength values with a predetermined adjustment value as a first set of adjusted signal strength values, and adjusting the signal strength values of the second set of signal strength values with said predetermined adjustment value as a second set of adjusted signal strength values;

a second summing portion summing the first set of adjusted signal strength is values as a first adjusted sum, and summing the second set of adjusted signal strength values as a second adjusted sum; and

,

a determining portion generating a weighting signal when a difference between said first and second adjusted sums is less than a predetermined threshold value and identifying the region that the wireless device is located by a comparison of the first adjusted sum with the second adjusted sum.

4. An apparatus according to claim 3 further including:

a selection circuit responsive to the determining portion to i) identify the region that the wireless device is located by said comparison of the first weighted sum with the second weighted sum when the weighting signal is generated, and ii) identify the region that the wireless device is located by said comparison of the first adjusted sum with the second adjusted sum when the weighting signal is not generated.

5. An apparatus according to claim 4 wherein:

the first weighting portion is responsive to the determining portion to weight the signal strength values of the first and second sets of signal strength values with said first and second sets of predetermined weights as said first and second sets of weighted signal strength values respectively only when said weighting signal is generated; and

,

the first summing portion is responsive to the determining portion to sum the first and second sets of weighted signal strength values as the first and second weighted sums respectively only when said weighting signal is generated.

6. An apparatus according to claim 2 further including:

a first memory operatively connected with the communication interface and the determination logic, the first memory being configured to store the predetermined adjustment value; and

,

a second memory operatively connected with the communication interface and the determination logic, the second memory being configured to store the first and second sets of predetermined weights.

7. An apparatus according to claim 6 further including:

a user interface operatively connected with the communication interface, the determination logic, and the first and second memories, the user interface providing a means for enabling a user of the wireless device locating apparatus to selectively modify;

i) the first and second sets of adjustment values or ii) the first and second sets of predetermined weights; and

,

a database including said first and second memories for enabling the associated user to selectively manipulate;

i) said first and second sets of predetermined weights or ii) said first and second sets of adjustment values.

8. An apparatus according to claim 2 wherein:

the first weighting portion is configured to selectively weight the signal strength values of the first and second sets of signal strength values based, respectively, on first and second sets of selectable weights.

9. An apparatus according to claim 2 wherein:

the communication interface is configured to acquire received signal strength indicator (RSSI) data for the associated wireless device as said first and second sets of signal strength values.

10. A method of locating an associated wireless device, the method comprising:

receiving signal strength values including a first set of signal strength values for an associated wireless device detected at a first plurality of radio receivers disposed in a first region and a second set of signal strength values for the associated wireless device detected at a second plurality of radio receivers disposed in a second region; and

,

determining a region that the associated wireless device is located by;

selectively weighting the signal strength values of the first set of signal strength values with at least two different weight values as a first set of weighted signal strength values, and selectively weighting the signal strength values of the second set of signal strength values with at least two different weight values as a second set of weighted signal strength values;

summing the first set of weighted signal strength values as a first weighted sum, and summing the second set of weighted signal strength values as a second weighted sum; and

,

identifying the region that the wireless device is located by a comparison of the first weighted sum with the second weighted sum.

11. A method according to claim 10 wherein:

the determining includes selectively sorting the signal strength values of the first set of signal strength values as a first set of sorted signal strength values and sorting the signal strength values of the second set of signal strength values as a second set of sorted signal strength values; and

,

the weighting includes selectively weighting the signal strength values of the first and second sets of sorted signal strength values by applying, respectively, a first set of predetermined weights having at least two different weight values against the first set of sorted signal strength values as said first set of weighted signal strength values and a second set of predetermined weights having at least two different weight values against the second set of sorted signal strength values as said second set of weighted signal strength values.

12. A method according to claim 11 wherein the determining further includes:

adjusting the signal strength values of the first set of signal strength values with a predetermined adjustment value as a first set of adjusted signal strength values, and adjusting the signal strength values of the second set of signal strength values with said predetermined adjustment value as a second set of adjusted signal strength values;

summing the first set of adjusted signal strength values as a first adjusted sum, and summing the second set of adjusted signal strength values as a second sum; and

,

generating a weighting signal when a difference between said first and second adjusted sums is less than a predetermined threshold value.

13. A method according to claim 12 wherein:

the identifying includes, responsive to the determining portion and when said weighting signal is generated, i) identifying the region that the wireless device is located by a comparison of the first weighted sum with the second weighted sum when the weighting signal is generated, and ii) identifying the region that the wireless device is located by a comparison of the first adjusted sum with the second adjusted sum when the weighting signal is not generated.

14. A method according to claim 13 wherein:

the weighting includes, responsive to the determining portion and only when said weighting signal is generated, weighting the signal strength values of the first and second sets of signal strength values with said first and second sets of predetermined weights as said first and second sets of weighted signal strength values respectively; and

,

the summing includes, responsive to the determining portion and only when said weighting signal is generated, summing the first and second sets of weighted signal strength values as the first and second weighted sums respectively.

15. A method according to claim 11 further including:

storing the adjustment value in a first memory; and

,

storing the weight values in a second memory.

16. A method according to claim 15 further including selectively modifying the adjustment value or the weight values using a user interface.

17. A method according to claim 11 wherein:

the weighting includes selectively weighting the signal strength values of the first and second sets of signal strength values based, respectively, on first and second sets of selectable weights.

18. A method according to claim 11 wherein:

the receiving includes acquiring received signal strength indicator (RSSI) data for the wireless device as said first and second sets of signal strength values.

19. A method of locating an associated wireless device, the method comprising:

receiving signal strength values including a first set of signal strength values for an associated wireless device detected at a first plurality of radio receivers disposed in a first region and a second set of signal strength values for the associated wireless device detected at a second plurality of radio receivers disposed in a second region; and

,

determining a region that the associated wireless device is located by;

comparing said first set of signal strength values with said second set of signal strength values; and

based on a result of said comparing, identifying the region that the associated wireless device is located by one of a group consisting of a first manipulation of the first and second sets of signal strength values, and a second manipulation of the first and second sets of signal strength values different than the first manipulation, the first manipulation including a weighting of said first and second sets of signal strength values and the second manipulation including an adjusting of said first and second sets of signal strength values.

20. The method according to claim 19 wherein said determining includes determining the region that the associated wireless device is located according to:

21. The method according to claim 19 wherein said determining includes determining the region that the associated wireless device is located according to:

22. The method according to claim 19 wherein said determining includes determining the region that the associated wireless device is located according to:

23. The method according to claim 19 wherein said determining includes determining the region that the associated wireless device is located according to: