Source: https://patents.google.com/patent/US9008584B2/en
Timestamp: 2018-12-16 18:51:11
Document Index: 124573022

Matched Legal Cases: ['§371', 'Application No. 2009902848', 'Application No. 2010262768', 'Application No. 201080036975', 'Application No. 10788518', 'Application No. 2012', 'Application No. 201109429']

US9008584B2 - Environment estimation in a wireless communication system - Google Patents
US9008584B2
US9008584B2 US13379295 US201013379295A US9008584B2 US 9008584 B2 US9008584 B2 US 9008584B2 US 13379295 US13379295 US 13379295 US 201013379295 A US201013379295 A US 201013379295A US 9008584 B2 US9008584 B2 US 9008584B2
US20120196541A1 (en )
A method and system are described for estimating an environment surrounding a wireless communication system, the environment including at least one inflector that inflects transmitted signals. An observation generator receives an input signal transmitted from a transmitter to a receiver via a wireless communication channel and also receives system state information pertaining to at least one of the receiver, the transmitter and the inflector. An observation processor uses observations from the observation generator to estimate at least one property of the inflector based on the received input signal and the system state information.
This application is a national stage application under 35 U.S.C. §371 of PCT/AU2010/000768, filed Jun. 18, 2010, and published as WO 2010/144973 A1 on Dec. 23, 2010, which claims priority to Australian Application No. 2009902848, filed Jun. 19, 2009, which applications and publication are incorporated herein by reference and made a part hereof in their entirety, and the benefit of priority of each of which is claimed herein.
FIGS. 10 A, B, C: illustrate an example solution for inflector position obtained by applying cost functions derived from constraints, to a first observation;
FIGS. 11A, B and C: illustrate an example solution for inflector position obtained by applying cost functions derived from constraints, to a second observation;
FIGS. 12 A, B and C: illustrate an example solution from combining solutions for inflector position obtained by applying cost functions derived from constraints, across both a first and a second observation.
The observation constructor 506 is provided with receiver information from the receiver 104, for example received signal samples and/or a channel estimate. The observation constructor also receives SSI pertaining to the transmitter, for example from SSI extractor 504 and also SSI pertaining to the receiver, for example from the SSI sources 502. The observation constructor 506 forms an observation 303 from the available receiver information and system state information. The observation is denoted Ω[i], where i is the observation index, and may include:
v → T · u → TP + ( v → P - v → R ) · u → PR = - c ⁢ ω ω 0 , ( Eq . ⁢ 3 )
T + L TP ⁢ u → TP = R - L PR ⁢ u → PR L TP + L PR - L TR = Δ ⁢ ⁢ t 12 ⁢ c v → T · u → TP + v → R · u → PR = - c ⁢ ω ω 0  u → TP  2 = 1  u → PR  2 = 1
T ⁡ [ i ] + L TP ⁡ [ i ] ⁢ u → TP ⁡ [ i ] = R ⁡ [ i ] - L PR ⁡ [ i ] ⁢ u → PR ⁡ [ i ] T ⁡ [ k ] + L TP ⁡ [ k ] ⁢ u → TP ⁡ [ k ] = R ⁡ [ k ] - L PR ⁡ [ k ] ⁢ u → PR ⁡ [ k ] L TP ⁡ [ i ] + L PR ⁡ [ i ] - L TR ⁡ [ i ] = Δ ⁢ ⁢ t 12 ⁡ [ i ] ⁢ c L TP ⁡ [ k ] + L PR ⁡ [ k ] - L TR ⁡ [ k ] = Δ ⁢ ⁢ t 12 ⁡ [ k ] ⁢ c v → T ⁡ [ i ] · u → TP ⁡ [ i ] + ( v → P - v → R ⁡ [ i ] ) · u → PR ⁡ [ i ] = - c ⁢ ω ⁡ [ i ] ω 0 v → T ⁡ [ k ] · u → TP ⁡ [ k ] + ( v → P - v → R ⁡ [ k ] ) · u → PR ⁡ [ k ] = - c ⁢ ω ⁡ [ k ] ω 0  u → TP ⁡ [ i ]  2 = 1  u → TP ⁡ [ k ]  2 = 1  u → PR ⁡ [ i ]  2 = 1  u → PR ⁡ [ k ]  2 = 1 T ⁡ [ i ] + L TP ⁡ [ i ] ⁢ u → TP ⁡ [ i ] + v → P ⁡ ( τ ⁡ [ k ] - τ ⁡ [ i ] ) = T ⁡ [ k ] + L TP ⁡ [ k ] ⁢ u → TP ⁡ [ k ]
{right arrow over (ν)}T [i]={right arrow over (ν)} T [k] and/or
C ⁡ ( Ω , P ~ , v → P ~ ) = abs ⁡ ( v → T · ( P ~ - T )  P ~ - T  2 + ( v → P ~ - v → R ) · ( R - P ~ )  R - P ~  2 + c ⁢ ω ω 0 )
C T = ∑ i ∈ Ω 1 ⁢ ⁢ a i ⁢ ⁢ 1 ⁢ C 1 ⁡ ( Ω ⁡ [ i ] , Φ ~ ) + ∑ i ∈ Ω 2 ⁢ ⁢ a i ⁢ ⁢ 2 ⁢ C 2 ⁡ ( Ω ⁡ [ i ] , Φ ~ ) + … + ∑ i ∈ Ω n ⁢ ⁢ a in ⁢ C n ⁡ ( Ω ⁡ [ i ] , Φ ~ ) , ( Eq . ⁢ 5 )
C ⁡ ( Ω ⁡ [ i ] , Ω ⁡ [ k ] , P ~ ⁡ [ i ] , P ~ ⁡ [ k ] ) = abs ⁡ (  P ~ ⁡ [ i ] - T ⁡ [ i ]  2 +  R ⁡ [ i ] - P ~ ⁡ [ i ]  2 - L TR ⁡ [ i ] - Δ ⁢ ⁢ t 12 ⁡ [ i ] ⁢ c ) + abs ⁡ (  P ~ ⁡ [ k ] - T ⁡ [ k ]  2 +  R ⁡ [ k ] - P ~ ⁡ [ k ]  2 - L TR ⁡ [ k ] - Δ ⁢ ⁢ t 12 ⁡ [ k ] ⁢ c ) ⁢ ⁢ ⁢ letting ⁢ ⁢ P ~ ⁡ [ i ] = P ~ ⁡ [ k ] - v → P ~ ⁡ ( τ ⁡ [ k ] - τ ⁡ [ i ] ) : ⁢ C ′ ⁡ ( Ω ⁡ [ i ] , Ω ⁡ [ k ] , P ~ ⁡ [ k ] ) = abs ⁡ (  P ~ ⁡ [ k ] - v → P ~ ⁡ ( τ ⁡ [ k ] - τ ⁡ [ i ] ) - T ⁡ [ i ]  2 +  R ⁡ [ i ] - P ~ ⁡ [ k ] + v → P ~ ⁡ ( τ ⁡ [ k ] - τ ⁡ [ i ] )  2 - L TR ⁡ [ i ] - Δ ⁢ ⁢ t 12 ⁡ [ i ] ⁢ c ) + abs ⁡ (  P ~ ⁡ [ k ] - T ⁡ [ k ]  2 +  R ⁡ [ k ] - P ~ ⁡ [ k ]  2 - L TR ⁡ [ k ] - Δ ⁢ ⁢ t 12 ⁡ [ k ] ⁢ c ) ( Eq . ⁢ 6 )
C ⁡ ( Ω , P ~ ) = abs ⁡ ( ⅆ ⅆ t ⁢  P ~ - T  2 + ⅆ ⅆ t ⁢  R - P ~  2 - ⅆ ⅆ t ⁢ L TR - ⅆ ⅆ t ⁢ Δ ⁢ ⁢ t 12 ⁢ c )
receiving system state information pertaining to at least one of the receiver, the transmitter and the at least one inflector; and
estimating at least one property of said at least one inflector based on the received input signal and the system state information, the at least one property at least partially inducing the wireless communication channel,
2. The method as claimed in claim 1 wherein said estimating estimates said at least one property selected from the group of:
issuing an alert dependent on the at least one estimated property of the at least one inflector.
comparing the at least one estimated property of the at least one inflector with mapped information descriptive of the environment; and
generating an estimate of the wireless communication channel between the transmitter and the receiver.
8. The method as claimed in claim 7 comprising using at least one additional feature of said estimate of the communication channel induced by the presence of at least one additional inflector to determine at least one said inflector property for said additional inflector.
9. The method as claimed in claim 8 wherein said additional channel feature is a time domain tap in said time domain channel estimate.
10. The method as claimed in claim 1, wherein said step of receiving system state information comprises extracting system state information pertaining to the transmitter from the received input signal.
11. The method as claimed in claim 1, comprising
12. The method as claimed in claim 11 wherein additional system state information pertaining to the transmitter is derived at the receiver.
13. The method as claimed in claim 12 wherein said derived input system state information pertaining to the transmitter includes at least one of:
15. The method as claimed in claim 1, comprising generating observations for use in said estimating wherein said observations relate to at least one of the following cases:
each of a plurality of received input signals corresponding to multiple transmitted signals separated in time;
each of a plurality of received input signals corresponding to multiple transmitted signals overlapped in time;
16. The method as claimed in claim 15 comprising:
18. The method as claimed in claim 1, wherein said estimating comprises applying at least one constraint upon at least one property of at least one said inflector.
19. The method as claimed in claim 18 wherein said estimating is constrained such that:
20. The method as claimed in claim 18 wherein said estimating is constrained such that:
L TP +L PR −L TR −Δt 12c=0
LTR=∥{right arrow over (TR)}∥ is the distance between points T and R;
Δt12=t2−t1 is a tap delay difference between two time-domain channel taps, from a direct signal propagation path at time t1 and an inflected signal propagation path at time t2, LTP=∥{right arrow over (TP)}∥2 is the distance between points T and P; LPR=∥{right arrow over (PR)}∥2 is the distance between points P and R; and
21. The method as claimed in claim 20 comprising determining said tap delay difference parameter Δt12 from an estimate of the communication channel.
22. The method as claimed in claim 21 comprising determining said tap delay difference parameter Δt12 by measuring a delay difference between taps corresponding to the direct path and inflected path in said estimate of the communication channel in the time domain.
23. The method as claimed in claim 18 wherein said estimating is constrained such that:
v → T · u → TP + ( v → P - v → R ) · u → PR + c ⁢ w w 0 = 0
{right arrow over (ν)}T is the instantaneous velocity vector for the transmitter;
is the unit vector in the direction of {right arrow over (PR)}; and
denotes vector dot product.
24. The method as claimed in claim 23, comprising
25. The method as claimed in claim 24 wherein said frequency offset parameter ω is calculated from said channel estimate, ĥ, in the time domain, as the rate of change of phase of the tap corresponding to the inflected path relative to that of the tap corresponding to the direct path.
26. The method as claimed in claim 24 wherein calculation of said frequency offset parameter ω from said channel estimate is performed for at least one of the following cases:
27. The method as claimed in claim 18 wherein said estimating is constrained such that:
∥{right arrow over (u)}∥ 2−1=0; and
∥{right arrow over (u)}∥ 2−1=0, where:
is the unit vector in the direction of {right arrow over (PR)}.
28. The method as claimed in claim 18 wherein said constraints are applied across a plurality of observations under some assumption on the position of one or more system components with respect to time, the system components comprising at least one of the inflector, the transmitter, the receiver and a source of system state information.
29. The method as claimed in claim 28 wherein said estimating is constrained across a plurality of observations such that:
T[i]+L TP [i]{right arrow over (u)} TP [i]+{right arrow over (ν)} P(τ[k]−τ[i])−L TP [k]{right arrow over (u)} TP [k]=0
τ[i] is the time at which observation i was taken;
τ[k] is the time at which observation k was taken;
T[i] is a point representing the position of the transmitter with respect to observation i;
T[k] is a point representing the position of the transmitter with respect to observation k;
LTP=∥{right arrow over (TP)}∥2 is the distance between points T and P; and
{right arrow over (ν)}P is the instantaneous velocity vector for the inflector.
30. The method as claimed in claim 18 comprising deriving further constraints for said estimating by differentiating with respect to time.
31. The method as claimed in claim 18 comprising: combining a plurality of said constraints to form a system of equations, and said estimating comprises solving said system using at least one input observation.
32. The method as claimed in claim 18 comprising making a hypothesis on inflector location {circumflex over (P)}[k]=P[i]+{right arrow over (ν)}P(τ[k]−τ[i]) at time τ[k], and making a test that this hypothesis satisfies one or more of the constraints using an observation taken at time τ[k], where
{right arrow over (ν)}P is the instantaneous velocity vector for the inflector; and
P[i] is the inflector location with respect to observation i.
33. The method as claimed in claim 18 comprising
34. The method as claimed in claim 33 comprising selecting a set of points to be used as inflector location hypotheses by quantizing a region of the environment.
35. The method as claimed in claim 33 comprising selecting a set of instantaneous velocities as hypotheses for said estimating.
36. The method as claimed in claim 33 comprising combining a plurality of cost functions across at least one input observation.
37. The method as claimed in claim 36 wherein said cost functions are combined across said observations, after dividing said observations into n sets Ω1, Ω2, . . . , Ωn, as follows:
C T = ∑ i ∈ Ω 1 ⁢ ⁢ a i ⁢ ⁢ 1 ⁢ C 1 ⁡ ( Ω ⁡ [ i ] , Φ ~ ) + ∑ i ∈ Ω 2 ⁢ ⁢ a i ⁢ ⁢ 2 ⁢ C 2 ⁡ ( Ω ⁡ [ i ] , Φ ~ ) + … + ∑ i ∈ Ω n ⁢ ⁢ a in ⁢ C n ⁡ ( Ω ⁡ [ i ] , Φ ~ ) ,
aij is a weight applied to cost function j for observation i;
38. The method as claimed in claim 37 comprising combining one or more said cost functions across a plurality of input observations occurring at different times.
39. The method as claimed in claim 37 wherein said combination is performed for observations Ω[i] and Ω[k] using the substitution:
{tilde over (P)}[i]={tilde over (P)}[k]−{right arrow over (ν)} {tilde over (P)}(τ[k]−τ[i])
40. The method as claimed in claim 33 comprising
41. The method as claimed in claim 33 comprising:
42. The method as claimed in claim 1 wherein said estimating generates a set of feasible solutions for the inflector property.
43. The method as claimed in claim 42 comprising reducing the set of feasible inflector property solutions using at least one of:
additional input observations.
44. The method as claimed in claim 43 wherein the additional observations are provided by at least one of the following:
45. The method as claimed in claim 1 comprising constraining an estimated speed of the inflector.
46. The method as claimed in claim 45 where said constraint on inflector speed comprises at least one of:
47. The method as claimed in claim 1 comprising constraining the at least one inflector property by considering the inflector to be at least one of:
48. The method as claimed in claim 1 comprising:
50. The method as claimed in claim 1 wherein said input signal includes the position of the transmitter.
51. An apparatus for estimating an environment surrounding a wireless communication system, the environment including at least one inflector that inflects transmitted signals, the apparatus comprising:
an environment estimator for estimating at least one property of the inflector based on the received input signal and the system state information, the at least one property at least partially inducing the wireless communication channel,
52. The apparatus as claimed in claim 51 wherein said input signal includes the position of the transmitter.
53. A system for estimating an environment surrounding a wireless communication system, the environment including at least one inflector that inflects transmitted signals, the system comprising:
an environment estimator in data communication with the receiver and the at least one source of system state information for estimating at least one property of the inflector based on the received input signal and the system state information, the at least one property at least partially inducing the wireless communication channel,
54. The system as claimed in claim 53 wherein at least one of the transmitter, receiver and inflector moves.
55. The system as claimed in claim 53 wherein said at least one transmitter and receiver are collocated.
56. The system as claimed in claim 53 wherein said input signal includes the position of the transmitter.
57. A computer program product comprising machine readable program code recorded on a non-transitory machine-readable recording medium, for controlling the operation of a data processing apparatus on which the program code executes to perform a method for estimating an environment surrounding a wireless communication system, the environment including at least one inflector that inflects transmitted signals, the method comprising:
estimating at least one property of the inflector based on the received input signal and the system state information, the at least one property at least partially inducing the wireless communication channel,
58. The computer program product as claimed in claim 57 wherein said input signal includes the position of the transmitter.
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