Estimating the Location of a Wireless Terminal Based on Non-Uniform Probabilities of Movement
AssigneePolaris Wireless, Inc.
InventorsDavid Stevenson Spain, Jr., Robert Morris Dressler
Life of this patent
Estimating the term…
Abstract
A technique for estimating the location of a wireless terminal at an unknown location in a geographic region is disclosed. The technique is based on the recognition that there are traits of electromagnetic signals that are dependent on topography, the receiver, the location of the transmitter, and other factors. For example, if a particular radio station is known to be received strongly at a first location and weakly at a second location, and a given wireless terminal at an unknown location is receiving the radio station weakly, it is more likely that the wireless terminal is at the second location than at the first location.
Claims23
A method comprising estimating the location of a wireless terminal at time t from among a plurality of candidate locations based on:
- (i) a first probability distribution for the location of said wireless terminal at time t among said plurality of candidate locations;
- (ii) a second probability distribution for the location of said wireless terminal at time t−Δ among said plurality of candidate locations, wherein Δ is nonzero;
- and
- (iii) one or more of a plurality of non-isotropic transition probabilities for said wireless terminal moving among said plurality of candidate locations from the earlier of time t and time t−Δ to the later of time t and time t−Δ.
A method comprising estimating the location of a wireless terminal at time t based on:
- (i) a first probability distribution for the location of said wireless terminal at time t, wherein said first probability distribution is generated by a process that is independent of the location history of said wireless terminal;
- and
- (ii) a second probability distribution for the location of said wireless terminal at time t, wherein said second probability distribution is based on
- (a) an estimated location of said wireless terminal at time t−Δ, wherein Δ>0, and
- (b) one or more of a plurality of non-isotropic transition probabilities for the movement of said wireless terminal from time t−Δ to time t.
A method comprising estimating the location of a wireless terminal at time t based on:
- (i) a first probability distribution for the location of said wireless terminal at time t, wherein said first probability distribution is generated by a process that is independent of any subsequent movement of said wireless terminal;
- and
- (ii) a second probability distribution for the location of said wireless terminal at time t, wherein said second probability distribution is based on
- (a) an estimated location of said wireless terminal at time t+Δ, wherein Δ>0, and
- (b) one or more of a plurality of non-isotropic transition probabilities for the movement of said wireless terminal from time t to time t+Δ.
A method comprising estimating the location of a wireless terminal at time t from among a plurality of candidate locations based on:
- (i) a first probability distribution for the location of said wireless terminal at time t among said plurality of candidate locations;
- (ii) a second probability distribution for the location of said wireless terminal at time t−Δ among said plurality of candidate locations, wherein Δ is nonzero;
- (iii) a first transition probability p1 for said wireless terminal moving from a first location, L1, of said plurality of candidate locations to a second location, L2, of said plurality of candidate locations L2 from the earlier of time t and time t−Δ to the later of time t and time t−Δ;
- and
- (iv) a second transition probability p2 for said wireless terminal moving from said first candidate location L1 to a third location, L3, of said plurality of candidate locations from the earlier of time t and time t−Δ to the later of time t and time t−Δ;
- wherein the distance between L1 and L2 equals the distance between L2 and L3;
- and wherein p1≠p2.
A method comprising estimating the location of a wireless terminal at time t from among a plurality of candidate locations based on:
- (i) a first probability distribution for the location of said wireless terminal at time t among said plurality of candidate locations;
- (ii) a second probability distribution for the location of said wireless terminal at time t−Δ among said plurality of candidate locations, wherein Δ is nonzero;
- (iii) a first transition probability p1 for said wireless terminal moving from a first location, L1, of said plurality of candidate locations to a second location, L2, of said plurality of candidate locations from the earlier of time t and time t−Δ to the later of time t and time t−Δ;
- and
- (iv) a second transition probability p2 for said wireless terminal moving from said first candidate location, L1, to a third location, L3, of said plurality of candidate locations from the earlier of time t and time t−Δ to the later of time t and time t−Δ;
- wherein p1=p2;
- and
- wherein the distance between L1 and L2 does not equal the distance between L2 and L3.
Dependencies are inferred from the claim text.