Systems and methods for monitoring selected terrestrially used satellite frequency signals to reduce potential interference

• US 7,447,501 B2
• Filed: 05/19/2005
• Issued: 11/04/2008
• Est. Priority Date: 09/14/2001
• Status: Expired due to Term

• Current Assignee: ATC Technology Corporation (FedEx Corporation)
• Original Assignee: ATC Technology Corporation (FedEx Corporation)
• Inventors: Karabinis, Peter D.
• Primary Examiner(s): GESESSE, TILAHUN
• Application Number:
  US11/133,102
• Publication Number:
  US 20050208890A1
• Time in Patent Office: 1,265 Days
• Field of Search: 455/12.1, 455/13.1, 455/427, 455/428, 455/429, 455/430
• US Class Current: 455/427
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00

Abstract

A satellite radiotelephone frequency band can be reused terrestrially by an ancillary terrestrial network even within the same satellite cell, using interference reduction/cancellation techniques. An interference reducer is responsive to a space-based component and to an ancillary terrestrial network. The interference reducer is configured to reduce interference in wireless communications that are received by the space-based component from first radiotelephones in the satellite footprint over a satellite radiotelephone frequency band using wireless communications that are received by the ancillary terrestrial network from selected ones of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or wireless communications that are transmitted by the ancillary terrestrial network to the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band. The interference reducer may include a prefilter that is configured to determine the selected ones of the second radiotelephones.

Claims

1. A satellite radiotelephone system comprising:

a space-based component that is configured to receive wireless communications from a plurality of first radiotelephones in a satellite footprint over a satellite radiotelephone frequency band;

an ancillary terrestrial network that is configured to receive/transmit wireless communications from/to a plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the space-based component also receiving the wireless communications from the second radiotelephones and/or the ancillary terrestrial network in the satellite footprint over the satellite radiotelephone frequency band as interference along with the wireless communications that are received from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band; and

an interference reducer that is responsive to the space-based component and to the ancillary terrestrial network, and that is configured to reduce the interference in the wireless communications that are received by the space-based component from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from selected ones of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones,

wherein the second radiotelephones are closer to the ancillary terrestrial network than to the space-based component such that the wireless communications from the second radiotelephones are received by the ancillary terrestrial network prior to reception by the space based component, and wherein the interference reducer is configured to generate at least one delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network and/or at least one delayed replica of the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones and to subtract the delayed replica(s) of the wireless communications from the wireless communications that are received from the space-based component.

2. A satellite radiotelephone system according to claim 1 wherein the interference reducer comprises a prefilter that is configured to determine the selected ones of the second radiotelephones.

3. A satellite radiotelephone system according to claim 2 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

4. A satellite radiotelephone system according to claim 3 in combination with the plurality of second radiotelephones wherein the second radiotelephones are configured to transmit to the ancillary terrestrial network and/or the space-based component, the measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

5. A satellite radiotelephone system according to claim 4 wherein the ancillary terrestrial network is configured to transmit to the interference reducer signals received by the ancillary terrestrial network from the selected ones of the second radiotelephones, before and/or after demodulation, de-spreading and/or regeneration of the signals by the ancillary terrestrial network.

6. A satellite radiotelephone system according to claim 5 wherein the interference reducer is configured re-modulate and/or re-spread the signals of the selected ones of the second radiotelephones that are received by the interference reducer from the ancillary terrestrial network.

7. A satellite radiotelephone system according to claim 6 wherein the interference reducer is configured to re-spread the signals at the chip level and/or at the symbol level.

8. A satellite radiotelephone system according to claim 3 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component exceeding a fixed and/or variable threshold.

9. A satellite radiotelephone system according to claim 2 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a random or pseudo-random selection, a percentage of the plurality of second radiotelephones satisfying a geographic criterion and/or a likelihood that that the wireless communications that are received by the space-based component from the second radiotelephones will cause interference with the wireless communications that are received by the space-based component from the first radiotelephones.

10. A satellite radiotelephone system according to claim 1 wherein the interference reducer comprises an adaptive interference reducer.

11. A satellite radiotelephone system according to claim 1 further comprising a gateway that communicates with the space-based component and with the ancillary terrestrial network and wherein the interference reducer is at least partially included in the gateway.

12. An interference reducer for a satellite radiotelephone system, the satellite radiotelephone system comprising a space-based component that is configured to receive wireless communications from a plurality of first radiotelephones in a satellite footprint over a satellite radiotelephone frequency band and an ancillary terrestrial network that is configured to receive wireless communications from a plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or transmit wireless communications to the plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the space-based component also receiving the wireless communications from the second radiotelephones and/or from the ancillary terrestrial network in the satellite footprint over the satellite radiotelephone frequency band as interference along with the wireless communications that are received from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the interference reducer comprising:

an electronics system that is responsive to the space-based component and to the ancillary terrestrial network, and that is configured to reduce the interference in the wireless communications that are received by the space-based component from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from selected ones of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band,

wherein the second radiotelephones are closer to the ancillary terrestrial network than to the space-based component such that the wireless communications from the second radiotelephones are received by the ancillary terrestrial network prior to reception by the space based component. and wherein the interference reducer is further configured to generate at least one delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network and/or at least one delayed replica of the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones and to subtract the delayed replica(s) of the wireless communications from the wireless communications that are received from the space-based component.

13. An interference reducer according to claim 12 further comprising:

a prefilter that is configured to determine the selected ones of the second radiotelephones.

14. An interference reducer according to claim 13 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

15. An interference reducer according to claim 14 wherein the interference reducer is further configured to receive, from the plurality of second radiotelephones via the ancillary terrestrial network and/or the space-based component, the measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

16. An interference reducer according to claim 15 wherein the interference reducer is configured to receive from the ancillary terrestrial network signals associated with the selected ones of the second radiotelephones, before and/or after demodulation, de-spreading and/or regeneration of the signals by the ancillary terrestrial network.

17. An interference reducer according to claim 16 wherein the interference reducer is further configured to re-modulate and/or re-spread the signals of the selected ones of the second radiotelephones that are received by the interference reducer from the ancillary terrestrial network.

18. An interference reducer according to claim 17 wherein the interference reducer is configured to re-spread the signals at the chip level and/or at the symbol level.

19. An interference reducer according to claim 14 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component exceeding a fixed and/or variable threshold.

20. An interference reducer according to claim 13 wherein the prefilter is configured to determine the selected ones of the second radiotelephones based on a random or pseudo-random selection, a percentage of the plurality of second radiotelephones based on location of the radiotelephones and/or a likelihood that the wireless communications that are received by the space-based component from the second radiotelephones will cause interference with the wireless communications that are received by the space-based component from the first radiotelephones.

21. An interference reducer according to claim 12 wherein the interference reducer comprises an adaptive interference reducer.

22. An interference reducer according to claim 12 wherein the satellite radiotelephone system further comprises a gateway that communicates with the space-based component and with the ancillary terrestrial network and wherein the interference reducer is at least partially included in the gateway.

23. An ancillary terrestrial network for a satellite radiotelephone system, the satellite radiotelephone system comprising a space-based component that is configured to receive wireless communications from a plurality of first radiotelephones in a satellite footprint over a satellite radiotelephone frequency band, the ancillary terrestrial network comprising:

a plurality of ancillary terrestrial components that are configured to receive/transmit wireless communications from/to a plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the space-based component also receiving the wireless communications from the second radiotelephones and/or the ancillary terrestrial network in the satellite footprint over the satellite radiotelephone frequency band as interference along with the wireless communications that are received from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band;

the satellite radiotelephone system further comprising an interference reducer that is responsive to the space-based component and to the ancillary terrestrial network, and that is configured to reduce the interference in the wireless communications that are received by the space-based component from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from selected ones of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones; and

the ancillary terrestrial network being further configured to transmit, to the interference reducer, a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component,

wherein the ancillary terrestrial network is closer to the second radiotelephones than is the space-based component such that the wireless communications from the second radiotelephones are received by the ancillary terrestrial network prior to reception by the space based component, and wherein the interference reducer is configured to generate at least one delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network and to subtract the delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network from the wireless communications that are received from the space-based component.

24. An ancillary terrestrial network according to claim 23 wherein the ancillary terrestrial network is further configured to transmit to the interference reducer, signals received by the ancillary terrestrial network from the selected ones of the second radiotelephones, before and/or after demodulation, de-spreading and/or regeneration of the signals by the ancillary terrestrial network.

25. An ancillary terrestrial network according to claim 23 wherein the interference reducer is at least partially included in the ancillary terrestrial network.

26. A satellite radiotelephone communication method comprising:

receiving wireless communications at a space-based component from a plurality of first radiotelephones in a satellite footprint over a satellite radiotelephone frequency band;

receiving/transmitting wireless communications at an ancillary terrestrial network from/to a plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the space-based component also receiving the wireless communications from the second radiotelephones and/or the ancillary terrestrial network in the satellite footprint over the satellite radiotelephone frequency band as interference along with the wireless communications that are received from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band; and

reducing the interference in the wireless communications that are received by the space-based component from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from selected ones of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones,

wherein the second radiotelephones are closer to the ancillary terrestrial network than to the space-based component such that the wireless communications from the second radiotelephones are received by the ancillary terrestrial network prior to reception by the space based component, and wherein reducing the interference comprises generating at least one delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network and/or at least one delayed replica of the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones and subtracting the delayed replica(s) of the wireless communications from the wireless communications that are received from the space-based component.

27. A method according to claim 26 wherein reducing the interference comprises prefiltering to determine the selected ones of the second radiotelephones.

28. A method according to claim 27 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

29. A method according to claim 28 further comprising:

transmitting from the second radiotelephones to the ancillary terrestrial network and/or the space-based component, the measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

30. A method according to claim 29 further comprising transmitting from the ancillary terrestrial network to the interference reducer signals received by the ancillary terrestrial network from the selected ones of the second radiotelephones, before and/or after demodulation, despreading and/or regeneration of the signals by the ancillary terrestrial network.

31. A method according to claim 30 wherein reducing the interference further comprises re-modulating and/or re-spreading the signals of the selected ones of the second radiotelephones that are received from the ancillary terrestrial network.

32. A method according to claim 30 wherein reducing the interference further comprises re-spreading the signals at the chip level and/or at the symbol level.

33. A method according to claim 28 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component exceeding a fixed and/or variable threshold.

34. A method according to claim 27 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a random or pseudo-random selection, a percentage of the plurality of second radiotelephones satisfying a geographic criterion and/or a likelihood that that the wireless communications that are received by the space-based component from the second radiotelephones will cause interference with the wireless communications that are received by the space-based component from the first radiotelephones.

35. A method according to claim 26 wherein reducing the interference comprises performing adaptive interference reducing.

36. A method according to claim 26 further comprising a gateway that communicates with the space-based component and with the ancillary terrestrial network and wherein reducing the interference is at least partially performed in the gateway.

37. An interference reducing method for a satellite radiotelephone system, the satellite radiotelephone system comprising a space-based component that is configured to receive wireless communications from a plurality of first radiotelephones in a satellite footprint over a satellite radiotelephone frequency band and an ancillary terrestrial network that is configured to receive wireless communications from a plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or transmit wireless communications to the plurality of second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the space-based component also receiving the wireless communications from the second radiotelephones and/or from the ancillary terrestrial network in the satellite footprint over the satellite radiotelephone frequency band as interference along with the wireless communications that are received from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, the interference reducing method comprising:

reducing the interference in the wireless communications that are received by the space-based component from the first radiotelephones in the satellite footprint over the satellite radiotelephone frequency band, using the wireless communications that are received by the ancillary terrestrial network from selected ones of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency band and/or the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones in the satellite footprint over the satellite radiotelephone frequency bands,

wherein the second radiotelephones are closer to the ancillary terrestrial network than to the space-based component such that the wireless communications from the second radiotelephones are received by the ancillary terrestrial network prior to reception by the space based component and wherein reducing the interference further comprises generating at least one delayed replica of the wireless communications from the selected ones of the second radiotelephones that are received by the ancillary terrestrial network and/or at least one delayed replica of the wireless communications that are transmitted by the ancillary terrestrial network to at least some of the second radiotelephones and subtracting the delayed replica(s) of the wireless communications from the wireless communications that are received from the space-based component.

38. A method according to claim 37 wherein reducing the interference comprises prefiltering to determine the selected ones of the second radiotelephones.

39. A method according to claim 38 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

40. A method according to claim 38 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a random or pseudo-random selection, a percentage of the plurality of second radiotelephones based on location of the radiotelephones and/or a likelihood that the wireless communications that are received by the space-based component from the second radiotelephones will cause interference with the wireless communications that are received by the space-based component from the first radiotelephones.

41. A method according to claim 37 further comprising receiving from the plurality of second radiotelephones via the ancillary terrestrial network and/or the space-based component, the measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component.

42. A method according to claim 41 wherein reducing the interference comprises receiving from the ancillary terrestrial network signals associated with the selected ones of the second radiotelephones, before and/or after demodulation, de-spreading and/or regeneration of the signals by the ancillary terrestrial network.

43. A method according to claim 42 wherein reducing the interference further comprises re-modulating and/or re-spreading the signals of the selected ones of the second radiotelephones that are received by the interference reducer from the ancillary terrestrial network.

44. A method according to claim 43 wherein reducing the interference further comprises re-spreading the signals at the chip level and/or at the symbol level.

45. A method according to claim 37 wherein prefiltering comprises determining the selected ones of the second radiotelephones based on a measure of signal strength of wireless signals that are received by the plurality of second radiotelephones from the space-based component exceeding a fixed and/or variable threshold.

46. A method according to claim 37 wherein reducing the interference comprises performing adaptive interference reducing.

47. A method according to claim 37 further comprises a gateway that communicates with the space-based component and with the ancillary terrestrial network and wherein reducing the interference is at least partially performed in the gateway.