System and method for estimating separation distance between impulse radios using impulse signal amplitude

• US 20050184908A1
• Filed: 02/23/2004
• Published: 08/25/2005
• Est. Priority Date: 03/29/2000
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Richards, James L.
• Granted Patent: US 7,151,490 B2
• Time in Patent Office: Days
• US Class Current: 342/458
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: H04B 2001/6908 using time hopping

Abstract

An impulse radio system estimates a separation distance between an impulse radio transmitter and an impulse radio receiver. The system includes an impulse transmitter that transmits an impulse signal having an ultra-wideband frequency characteristic. An impulse receiver spaced from the transmitter receives the transmitted impulse signal and measures a signal strength of the received impulse signal. The receiver estimates the separation distance based on the measured signal strength. The receiver classifies a signal propagational/multipath environment using the received impulse signal, and then selects a radio propagation path loss model corresponding to a classified multipath environment. The receiver translates the measured signal strength to a separation distance based on the selected radio propagation path loss model.

Claims

1-24. -24. (canceled)

25. A method for locating an impulse radio, comprising:

communicating impulse signals between a first impulse radio and a plurality of second impulse radios;

performing a received signal strength measurement for each of the impulse signals;

selecting one of a plurality of radio propagation path models;

estimating a separation distance between the first impulse radio and each of the plurality of second impulse radios based on a corresponding one of the received signal strength measurements and the radio propagation path model to produce a plurality of separation distances; and

determining a location relating to the first impulse radio based on the plurality of separation distances.

26. The method of claim 25, wherein the first impulse radio comprises an impulse radio transmitter and at least one of the plurality of second impulse radios comprises an impulse radio receiver.

27. The method of claim 25, wherein the first impulse radio comprises an impulse radio receiver and at least one of the plurality of second impulse radios comprises an impulse radio transmitter.

28. The method of claim 25, wherein at least one of the first impulse radio and the second impulse radio comprises one of a hand held unit, a mobile unit, and a fixed unit.

29. The method of claim 25 further comprises classifying a multipath environment for selecting one of the radio propagation path models.

30. The method of claim 29, wherein the multipath environment is classified based on a signal strength decay envelope.

31. The method of claim 25, wherein each of the impulse signals has one of ultra-wideband frequency characteristics and medium wideband frequency characteristics.

32. The method of claim 25 further comprises determining a decay time of at least one of the impulse signals.

33. The method of claim 32, wherein said selecting a radio propagation path model comprises:

matching the decay time to one of a plurality of predetermined decay time ranges, each decay time range being associated with a respective one of a plurality of radio propagation path models; and

selecting a radio propagation path model associated with the matched decay time range.

34. The method of claim 25, wherein the radio propagation path model is selected from one of:

P=k₁r^a1, 

 

(1)
P=k₂r^a2, and 

 

(2)
P_avg=k₃r^a3, 

 

(3)

where

P represents a signal strength of a received impulse signal,

P_avg is an average signal strength of a predetermined number of received impulse signals,

k₁, k₂, and k₃ are proportionality constants,

a₁, a₂, and a₃ are real numbers in the approximate range of −

2 to −

4, and

r is a separation distance between the transmitter and the receiver.

35. A method for locating an impulse radio transmitter, comprising:

transmitting an impulse signal from the impulse radio transmitter;

receiving the impulse signal at each of a plurality of impulse radio receivers;

performing a received signal strength measurement for the impulse signal at each of the plurality of impulse radio receivers;

selecting one of a plurality of radio propagation path models;

estimating a separation distance between each of the plurality of impulse radio receivers and the impulse radio transmitter based on a corresponding one of the received signal strength measurements and the selected radio propagation path model to produce a plurality of separation distances; and

determining a location relating to the impulse radio transmitter based on the plurality of separation distances.

36. A method for locating an impulse radio receiver, comprising:

transmitting an impulse signal from a plurality of impulse radio transmitters;

receiving the impulse signals at the impulse radio receiver;

performing a received signal strength measurement for each of the impulse signals;

selecting one of a plurality of radio propagation path models;

estimating a separation distance between each of the plurality of impulse radio transmitters and the impulse radio receiver based on a corresponding one of the received signal strength measurements and the selected radio propagation path model to produce a plurality of separation distances; and

determining a location relating to the impulse radio receiver based on the plurality of separation distances.

37. A system for locating an impulse radio, comprising:

a first impulse radio; and

a plurality of second impulse radios communicating impulse signals with said first impulse radio;

at least one received signal strength indicator that performs a received signal strength measurement for the impulse signals;

at least one signal evaluator that selects one of a plurality of radio propagation path models; and

at least one processor that estimates a separation distance between the first impulse radio and each of the plurality of second impulse radios based on a corresponding one of the received signal strength measurements and the selected radio propagation path model to produce a plurality of separation distances, said plurality of separation distances being used for determining a location relating to the first impulse radio.

38. The system of claim 37, wherein the first impulse radio comprises an impulse radio transmitter and at least one of the plurality of second impulse radios comprises an impulse radio receiver.

39. The system of claim 37, wherein the first impulse radio comprises an impulse radio receiver and at least one of the plurality of second impulse radios comprises an impulse radio transmitter.

40. The system of claim 37, wherein at least one of the first impulse radio and the second impulse radio comprises one of a hand held unit, a mobile unit, and a fixed unit.

41. The system of claim 37, wherein a multipath environment is classified to select one of the radio propagation path models.

42. The system of claim 41, wherein the multipath environment is classified based on a signal strength decay envelope.

43. The system of claim 41, the multipath environment is classified by determining a decay time of at least one of the impulse signals.

44. The system of claim 43, wherein said signal evaluator selects a radio propagation path model by matching the decay time to one of a plurality of predetermined decay time ranges, each decay time range being associated with a respective one of a plurality of radio propagation path models;

and by

selecting a radio propagation path model associated with the matched decay time range.

45. The system of claim 37, wherein each of plurality of impulse signals has one of ultra-wideband frequency characteristics and medium wideband frequency characteristics.

46. The system of claim 37, wherein the radio propagation path model is selected from one of:

P=k₁r^a1, 

 

(1)
P=k₂r^a2, and 

 

(2)
P_avg=k₃r^a3, 

 

(3)

where

P represents a signal strength of a received impulse signal,

P_avg is an average signal strength of a predetermined number of received impulse signals,

k₁, k₂, and k₃ are proportionality constants,

a₁, a₂, and a₃ are real numbers in the approximate range of −

2 to −

4, and

r is a separation distance between the transmitter and the receiver.

47. A system for locating an impulse radio transmitter, comprising:

a plurality of impulse radio receivers for receiving an impulse signal transmitted from the impulse radio transmitter;

at least one received strength signal indicator that performs a received signal strength measurement on the impulse signal at each of the plurality of impulse radio receivers;

at least one signal evaluator that selects one of a plurality of radio propagation path models; and

at least one processor that estimates a separation distance between each of the plurality of impulse radio receivers and the impulse radio transmitter based on a corresponding one of the received signal strength measurements and the selected radio propagation path model to produce a plurality of separation distances, said plurality of separation distances being used for determining a location relating to the impulse radio transmitter.

48. A system for locating an impulse radio receiver, comprising:

a plurality of impulse radio transmitters each transmitting an impulse signal;

an impulse radio receiver for receiving the impulse signals;

a received signal strength indicator that performs a received signal strength measurement for each of the impulse signals;

a signal evaluator that selects one of a plurality of radio propagation path models; and

a processor that estimates a separation distance between each of the plurality of impulse radio transmitters and the impulse radio receiver based on a corresponding one of the received signal strength measurements and the selected radio propagation path model to produce a plurality of separation distances, said plurality of separation distances being used for determining a location relating to the impulse radio receiver.