Location estimation system, method and program

• US 8,138,974 B2
• Filed: 10/24/2008
• Issued: 03/20/2012
• Est. Priority Date: 10/25/2007
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Ide, Tsuyoshi, Kashima, Hisashi, Tajima, Akira, Tsuboi, Yuta, Hido, Shohei, Suzuki, Shoko, Takahashi, Rikiya, Takahashi, Toshihiro
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): McGue, Frank
• Application Number:
  US12/257,437
• Publication Number:
  US 20090109095A1
• Time in Patent Office: 1,243 Days
• Field of Search: 342/451, 342/417
• US Class Current: 342/417
• CPC Class Codes: G01S 5/02521 using a radio-map

Abstract

A location estimation method using label propagation. The achieved location estimation method is robust to variations in radio signal strengths and is highly accurate by using the q-norm (0<q<1), especially, for calculating the similarities among radio signal strength vectors. The accuracy in location estimation is further improved by putting more importance on the time-series similarities. Specifically, the time-series similarity is calculated by using time-series values indicating the temporal order of radio signal strengths during the measurement. If the time-series similarity is larger than the similarity between the radio signal strength vectors, the time-series similarity is preferentially used. The exponential attenuation function can also be used for calculating the similarities, instead of the q norm (0<q<1).

Claims

1. A system for estimating a location label of a vector dataset without any location label from a plurality of vector datasets respectively with location labels using a computer, the system comprising:

storage means provided in the computer;

means for storing the vector datasets in the storage means of the computer;

means for calculating the similarity between the vector dataset without any location label and each neighboring vector dataset with a location label, by using any one of a q-norm wherein 0<

q<

1 and an exponential attenuation function; and

means for estimating the location label of the vector data without any location label from the calculated similarities,

wherein the similarities are calculated by means of the following expression using the q-norm,

W_X^(i,j)=exp(−

∥

X⁽ⁱ⁾−

X^(j)∥

_q^q),

where X⁽ⁱ⁾ and X^(j) denote i-th and j-th vectors, respectively, and

2. A location estimation method for estimating a location from radio signal strength datasets by means of a computer, the method comprising the steps of:

preparing a plurality of radio signal strength vector datasets with location labels and a plurality of radio signal strength vector datasets without location labels, respectively, and then storing the prepared datasets in storage means of the computer;

setting, by means of the computer, an initial value of the plausibility score f⁽ⁱ⁾(c) wherein i=1. . . N and wherein N denotes the number of all the prepared radio signal strength vector datasets such that each of the radio signal strength vector datasets with location labels and the radio signal strength vector datasets without location labels has a location label c;

calculating, using the computer, the similarity W^(i,j) for each combination of i and j wherein i,j=1. . . N, by using any one of a q-norm wherein 0<

q<

1, of the radio signal strength vector and an exponential attenuation function;

calculating, by means of the computer, f⁽ⁱ⁾(c) for each of the radio signal strength vector datasets without location labels, by using the following expression

3. The method according to claim 2, wherein the step of calculating the similarity W^(i,j) includes the steps of:

calculating the temporal similarity W_t^(i,j); and

choosing, as the similarity W^(i,j), one having the larger value from the temporal similarity W_t^(i,j) and the spatial similarity calculated by using any one of the q-norm and the exponential attenuation function.

4. The method according to claim 3, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

W_t^(i,j)=p·

δ

(TID⁽ⁱ⁾=TID^(j))·

δ

(|t⁽ⁱ⁾−

t^(j)|=1)

where 0<

p≦

1 is a constant parameter, TID⁽ⁱ⁾ is the trace ID to which the i-th vector belongs, and t⁽ⁱ⁾ is the time of observation of the i-th vector.

5. The method according to claim 3, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

6. The method according to claim 2, wherein the spatial similarities are calculated using the following expression using the q-norm,

W_X^(i,j)=exp(−

∥

X⁽ⁱ⁾−

X^(j)∥

_q^q)

where X⁽ⁱ⁾ denotes the i-th radio signal strength vector, and

7. The method according to claim 6, wherein both q and σ

are set at 0.5.

8. The method according to claim 2, wherein the spatial similarities are calculated by using the following expression with an exponential attenuation function,

9. The method according to claim 2, wherein the spatial similarities are calculated by using the following expression using exponential attenuation function,

10. A program for estimating a location from radio signal strength datasets by means of a computer, the program causing the computer to execute the steps of:

preparing a plurality of radio signal strength vector datasets respectively with location labels and a plurality of radio signal strength vector datasets without location labels, and then storing the prepared datasets into storage means of the computer;

setting an initial value of the plausibility score f⁽ⁱ⁾(c) wherein i=1. . . N and wherein N denotes the number of all the prepared radio signal strength vector datasets that each of the radio signal strength vector datasets with location labels and the radio signal strength vector datasets without location labels has a location label c;

calculating the similarity W^(i,j) for each combination of i and j wherein i,j=1. . . N, by using any one of a q-norm wherein 0<

q<

1, of the radio signal strength vector and an exponential attenuation function;

calculating f⁽ⁱ⁾(c) for each of the radio signal strength vector datasets without location labels, by using the following expression

11. The program according to claim 10, wherein the step of calculating the similarity W^(i,j) includes the steps of:

calculating temporal similarity W_t^(i,j); and

choosing, as the similarity W^(i,j), one having the larger value from the temporal similarity W_t^(i,j) and the spatial similarity calculated by using any one of the q-norm and the exponential attenuation function.

12. The program according to claim 11, wherein the spatial similarity is calculated by using the following expression using exponential attenuation function

13. The program according to claim 11, wherein the spatial similarity is calculated by using the following expression with an exponential attenuation function,

14. The program according to claim 11, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

W_t^(i,j)=p·

δ

(TID⁽ⁱ⁾=TID^(j))·

δ

(|t⁽ⁱ⁾−

t^(j)|=1)

where 0<

q≦

1 is a constant parameter, TID⁽ⁱ⁾ is the trace ID to which the i-th vector belongs, and t ⁽ⁱ⁾ is the time of observation of the i-th vector.

15. The program according to claim 11, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

W_t^(i,j)=p·

δ

(TID⁽ⁱ⁾=TID^(j))·

exp(−

∥

t⁽ⁱ⁾−

t^(j)∥

_r^r)

Where,

16. The program according to claim 10, wherein the q-norm is calculated by using the following expression,

W_X^(i,j)=exp(−

∥

X⁽ⁱ⁾−

X^(j)∥

_q^q)

where X⁽ⁱ⁾ denotes the i-th radio signal strength vector and

17. The program according to claim 16, wherein both q and σ

are set at 0.5.

18. A system for estimating a location from radio signal strength datasets by means of a computer, the system comprising:

storage means;

means for preparing a plurality of radio signal strength vector datasets respectively with location labels and a plurality of radio signal strength vector datasets without location labels, and then storing the prepared datasets into the storage means;

means for setting an initial value of the plausibility score f⁽ⁱ⁾(c) wherein i=1. . . N and wherein N denotes the number of all the prepared radio signal strength vector datasets that each of the radio signal strength vector datasets with location labels and the radio signal strength vector datasets without location labels has a location label c;

means for calculating the similarity W^(i,j) for each combination of i and j wherein i,j=1. . . N by using any one of a q-norm wherein 0<

q<

1 of the radio signal strength vector and an exponential attenuation function;

means for calculating f⁽ⁱ⁾(c) for each of the radio signal strength vector datasets without location labels, by using the following expression

19. The system according to claim 18, wherein the means of calculating the similarity W^(i,j) includes:

means for calculating the temporal similarity W^(i,j); and

means of choosing as the similarity W^(i,j), one having the larger value from the temporal similarity W_t^(i,j) and the spatial similarity calculated by using any one of the q-norm and the exponential attenuation function.

20. The system according to claim 19, wherein the spatial similarity is calculated by using the following expression with an exponential attenuation function,

21. The system according to claim 19, wherein the spatial similarity is calculated by using the following expression with an exponential attenuation function,

22. The system according to claim 19, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

W_t^(i,j)=p·

δ

(TID⁽ⁱ⁾=TID^(j))·

δ

(|t⁽ⁱ⁾−

t^(j)|=1)

where 0<

p≦

1 is a constant parameter, TID⁽ⁱ⁾ is the trace ID to which the i-th vector belongs, and t ⁽ⁱ⁾ is the time of observation of the i-th vector.

23. The system according to claim 19, wherein the temporal similarity W_t^(i,j) is calculated by using the following expression,

24. The system according to claim 18, wherein the q-norm is calculated by using the following expression,

W_X^(i,j)=exp(−

∥

X⁽ⁱ⁾−

X^(j)∥

_q^q)

where X⁽ⁱ⁾ denotes the i-th radio signal strength vector and

25. The system according to claim 24, wherein both q and σ

are set at 0.5.

26. A system for estimating a location label of a vector dataset without any location label from a plurality of vector datasets respectively with location labels using a computer, the system comprising:

storage means provided in the computer;

means for storing the vector datasets in the storage means of the computer;

means for calculating the similarity between the vector dataset without any location label and each neighboring vector dataset with a location label, by using any one of a q-norm wherein 0<

q<

1 and an exponential attenuation function; and

means for estimating the location label of the vector data without any location label from the calculated similarities,

wherein the similarities are calculated by means of the following expression using an exponential attenuation function,

27. A system for estimating a location label of a vector dataset without any location label from a plurality of vector datasets respectively with location labels using a computer, the system comprising:

storage means provided in the computer;

means for storing the vector datasets in the storage means of the computer;

means for calculating the similarity between the vector dataset without any location label and each neighboring vector dataset with a location label, by using any one of a q-norm wherein 0<

q<

1 and an exponential attenuation function; and

means for estimating the location label of the vector data without any location label from the calculated similarities,

wherein the similarities are calculated by means of the following expression using an exponential attenuation function,