Location estimation in wireless telecommunication networks
View Patent ↗A method for estimating a receiver's location in a wireless communication environment having several channels. Each channel has at least one signal parameter that varies with location differently from the other channels. A set of calibration data is determined for each calibration point, each set including the location and at least one measured signal parameter for each of several channels. The calibration data serve as a basis for a statistical model of the signal parameters versus a receiver's location. A set of observed signal parameters is determined, the set including at least one signal parameter for each of several channels at the receiver's location. A location estimate approximating the location of the receiver is determined on the basis of the statistical model and the set of observed signal parameters.
1. A method for estimating a location (X) of a receiver (R, R′) in a wireless telecommunication environment (RN), the telecommunication environment comprising a plurality of channels for simultaneous communication, each channel having at least one signal parameter (V) that varies with location (X) differently from the other channels;
wherein the method comprises the steps of:
for each of a plurality of calibration points in the wireless telecommunication environment, determining a set of calibration data (CD), each set of calibration data comprising the location (X) of the respective calibration point and at least one measured signal parameter (V) for each of several channels at that calibration point;
on the basis of the sets of calibration data (CD), maintaining a statistical model (SM) of the signal parameters (V) of the several channels versus a receiver's location in the wireless telecommunication environment (RN);
determining a set of observed signal parameters (CO), the set comprising at least one observed signal parameter (V) for each of several channels at the location (X) of the receiver (R, R′); and
determining a location estimate (LE) approximating the location (X) of the receiver (R, R′) on the basis of the statistical model (SM) and the set of observed signal parameters (CO).
2. A method according to claim 1 , further comprising the receiver (R) sending the set of observed signal parameters (CO) to an external location estimation module (LEM) which sends the location estimate (LE) to the receiver.
3. A method according to claim 1 , further comprising the receiver (R′) storing a copy of the statistical model (SM) and determining the location estimate (LE) on the basis of the copy of the statistical model (SM).
4. A method according to claim 1 , further comprising maintaining the statistical model (SM) also based on prior information (PI) about the wireless environment's (RN) infrastructure.
5. A method according to any claim 1 , wherein the statistical model (SM) is or comprises a probabilistic model.
6. A method according to claim 5 , wherein the statistical model (SM) is or comprises a Bayesian network model.
7. A method according to claim 1 , wherein the signal parameters (V) in the statistical model (SM) are independent of each other, given the location (X).
8. A method according to claim 1 , further comprising reducing uncertainty concerning the receiver's location based on a history (OH) of the observed signal parameters.
9. A method according to claim 1 , further comprising modeling at least some of the signal parameters (V) by discrete variables whose values correspond to intervals or unions of intervals on the range of possible signal parameter values.
10. A method according to claim 1 , further comprising modeling the location (X) as a discrete variable.
11. A location estimating apparatus (LEM) for estimating a location (X) of a receiver (R, R′) in a wireless telecommunication environment (RN), the telecommunication environment comprising a plurality of channels for simultaneous communication, each channel having at least one signal parameter (V) that varies with location (X) differently from the other channels;
the location estimating apparatus comprising a model construction module (MCM) for:
receiving a set of calibration data (CD) for each of a plurality of calibration points in the wireless telecommunication environment, each set of calibration data comprising the location (X) of the respective calibration point and at least one measured signal parameter (V) for each of several channels at that calibration point; and
maintaining, on the basis of the sets of calibration data (CD), a statistical model (SM) of the signal parameters (V) of the several channels versus a receiver's location in the wireless telecommunication environment (RN); and a location calculation module (LCM) for:
receiving a set of observed signal parameters (CO), the set comprising at least one observed signal parameter (V) for each of several channels at the location (X) of the receiver (R, R′); and
determining a location estimate (LE) approximating the location (X) of the receiver (R, R′) on the basis of the statistical model (SM) and the set of observed signal parameters (CO).
12. A receiver (R, R′) comprising:
means for determining sets of observed signal parameters (CO), each set comprising at least one observed signal parameter (V) for each of several channels at the location (X) of the receiver (R), and
means for conveying the sets of observed signal parameters (CO) to a location calculation module (LCM) for determining a location estimate (LE) approximating the location (X) of the receiver (R) on the basis of said sets and a statistical model (SM) of the signal parameters (V) of the several channels versus a receiver's location in a wireless telecommunication environment (RN).
13. A receiver (R′) according to claim 12 , further comprising the location calculation module (LCM).
14. A receiver (R) according to claim 12 , wherein the means for conveying the sets of observed signal parameters comprises means (RI) for conveying the sets to an external location calculation module (LCM).
15. A receiver according to claim 12 , wherein at least some of the sets of observed signal parameters (CO) relate to networks the receiver is not attached to.