METHOD FOR OPTIMUM BANDWIDTH SELECTION OF TIME-OF-ARRIVAL ESTIMATORS

• US 20100295731A1
• Filed: 12/21/2007
• Published: 11/25/2010
• Est. Priority Date: 01/11/2007
• Status: Abandoned Application

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Chong, Chia-Chin, Watanabe, Fujio
• Application Number:
  US11/963,630
• Publication Number:
  US 20100295731A1
• Time in Patent Office: Days
• US Class Current: 342/387
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: H04W 64/003 locating network equipment
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal

Abstract

A method determines an optimum bandwidth that minimizes ranging error in a geolocation application. The method ensures that an optimum bandwidth is selected under all channel conditions (i.e., both line-of-sight (LOS) and non-LOS (NLOS) conditions). Additionally, the method is generic and system-independent, such that it is applicable to both coherent receivers (e.g., match filter (MF) based receivers), non-coherent receivers (e.g., energy detector (ED) based receivers) and any types of time-of-arrival (TOA) estimators (e.g., whether peak-detection or threshold-based TOA estimator), regardless of the signal-to-noise ratios (SNRs) under consideration.

Claims

1. A method for reducing range error, comprising:

estimating the range errors as a function of bandwidth using a time-of-arrival (TOA) estimator;

from the estimated range errors, calculating a mean, a bias and a root-mean-square error of the range errors; and

selecting a bandwidth that minimizes the bias and the root-mean-square error.

2. A method as in claim 1, wherein selecting the bandwidth comprises:

deriving parameter values of a model of the mean of the range errors, using the calculated mean, the calculated bias and the calculated root-mean-square error; and

selecting the parameter values that minimize the bias and the root-mean-square error.

3. A method as in claim 1, further comprising:

determining whether or not a line-of-sight (LOS) condition is present in the channel; and

upon determining the LOS condition is present, calculating the mean, the bias and the root-mean-square error taking only multipath error into account.

4. A method as in claim 3 wherein, upon determining that the LOS condition is not present, estimating a non-line-of-sight (NLOS) component of the range error using a material penetration coefficient.

5. A method as in claim 4, wherein the range error is estimated using a multipath error and the NLOS component.

6. A method as in claim 1, wherein the TOA estimator is provided in a coherent system.

7. A method as in claim 6, wherein the TOA estimator comprises a peak-detection TOA estimator.

8. A method as in claim 7, wherein the peak-detection TOA estimator uses a peak-detection scheme selected from the group consisting of a single search scheme, a search and substract scheme and a search, subtract and readjust scheme.

9. A method as in claim 6, wherein the TOA estimator comprises a threshold-based TOA estimator.

10. A method as in claim 9, wherein the threshold-based TOA estimator comprises a coarse estimator, followed by a fine estimator.

11. A method as in claim 1, wherein the TOA estimator is provided in a non-coherent system.

12. A method as in claim 11, wherein the TOA estimator comprises a threshold-based TOA estimator.

13. A method as in claim 12, wherein the threshold-based TOA estimator comprises a lead edge detector.

14. A method as in claim 6, wherein the optimum bandwidth selected will always minimize the ranging error (i.e., bias and RMSE) irrespective of the SNRs under considerations.