Satellite-based mobile communication system

• US 20040001720A1
• Filed: 12/12/2002
• Published: 01/01/2004
• Est. Priority Date: 06/27/2002
• Status: Abandoned Application

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Krill, Jerry A., Frank, Joe, Duncan, Donald D., Cipriano, Joseph, Sova, Raymond M., Moore, Craig R.
• Application Number:
  US10/317,456
• Publication Number:
  US 20040001720A1
• Time in Patent Office: Days
• US Class Current: 398/125
• CPC Class Codes: H04B 10/118 specially adapted for satellite communication
• CPC Class Codes: H04B 7/18508 with satellite system used as relay, i.e. aeronautical mobile satellite service
• CPC Class Codes: H04B 7/18521 Systems of inter linked satellites, i.e. inter satellite service for optical links between satellites H04B10/118

Abstract

A communications system for wireless transceiving of information, comprising at least one multiple beam scanning array transceiver located in a satellite for wirelessly transceiving the information; and at least two terminals at diverse locations capable of wirelessly transceiving the information between the terminals and the satellite. The multiple beam scanning array transceiver can be optically based, and contain micro-mirrors or optical switches. Also disclosed is an apparatus for determining atmospheric conditions for use in adjusting the multiple beam scanning array transceiver parameters.

Claims

1. A communications system for wireless transceiving of information, comprising:

at least one multiple beam scanning array transceiver contained in a satellite for wirelessly transceiving the information; and

at least two terminals at diverse locations capable of wirelessly transceiving said information between the terminals and the satellite.

2. The communications system of claim 1, wherein the multiple beam scanning array transceiver is a multiple beam optical array transceiver.

3. The communications system of claim 2, wherein the multiple beam optical array transceiver comprises:

at least one receive amplifier for amplifying received optical signals;

at least one transmit amplifier for amplifying optical signals prior to transmission;

at least one micro-electronic mechanical (MEM) mirror for reflecting free-space optical signals;

at least one bi-directional optical coupler connected to the receive amplifier and the transmit amplifier, and associated with the MEM mirror, for transmitting to and receiving from the connected amplifiers an optical signal, and reflecting a free-space optical signal onto and receiving a reflected free-space optical signal from the associated MEM mirror;

at least one holographic aperture for focusing free-space optical signals reflected from the MEM mirror and focusing received free-space optical signals onto the MEM mirror;

a controller for controlling the aiming of the MEM mirror.

4. The communications system of claim 2, wherein the multiple beam optical array transceiver comprises:

at least one receive amplifier for amplifying received optical signals;

at least one transmit amplifier for amplifying optical signals prior to transmission;

at least one bi-directional optical switch bank having a bi-directional fiber optic input and a plurality of bi-directional fiber optic outputs;

at least one bi-directional optical coupler connected to the receive amplifier and the transmit amplifier, and having a bi-directional port for communicating with the input of the switch bank;

at least one holographic aperture connected to the plurality of outputs of the switch bank for receiving and transmitting free-space optical signals; and

a controller for controlling the switch bank.

5. The communications system of claim 4, wherein the switch bank comprises a plurality of optical switches connected in a binary branch configuration connected between the input and the plurality of outputs of the switch bank for at least one of receiving an optical signal at the input of the switch bank and controlling a transmission direction of the free-space optical signals through the holographic aperture by directing the optical signal to one of the plurality of outputs according to the switching of the optical switches, and

receiving a free-space optical signal at one of the output ports of the switch bank by controlling the receiving direction of the multiple beam optical array transceiver according to the switching of the optical switches.

6. The communications system of claim 2, further comprising a millimeter wavelength array receive antenna, comprising:

a plurality of array antenna elements each capable of detecting focused millimeter wavelength energy and converting the focused millimeter wavelength energy into electrical signals; and

a millimeter wavelength lens for focusing incident millimeter energy onto at least one of said array antenna elements;

wherein said plurality of array antenna elements conform to an array focal contour of the millimeter wavelength lens.

7. The communications system of claim 2, further comprising a millimeter wavelength array transmit antenna, comprising:

a plurality of array antenna elements each capable of converting electrical signals into millimeter wavelength energy and emitting the millimeter wavelength energy; and

a millimeter wavelength lens for focusing the emitted millimeter wavelength energy;

wherein said plurality of array antenna elements conform to an array focal contour of the millimeter wavelength lens.

8. The communications system of claim 7, wherein the millimeter wavelength array transmit antenna is located in a satellite and transmits at steep angles from zenith for minimizing the travel distance of the millimeter wavelength energy.

9. The communications system of claim 2, further comprising a microwave communication system for providing microwave communication capabilities to the satellite.

10. The communications system of claim 2, wherein the satellite is one of a low earth orbit (LEO), medium earth orbit (MEO), and geosynchronous orbit (GEO) satellite.

11. The communications system of claim 2, wherein the at least two terminals each comprise an optical transmitter and a mm wavelength transmitter.

12. The communications system of claim 2, wherein at least two satellites are included in the system and the at least two satellites contain an optical communication channel for transferring information between the at least two satellites.

13. The communications system of claim 2, wherein the system includes a global positioning system and a tracking system for providing positioning information of the terminals and for providing tracking of the optical signals between the terminals and the at least one satellite.

14. The communications system of claim 2, wherein each terminal is one of a telephone, a cellular telephone, a personal digital assistant, or personal computer.

15. The communications system of claim 2, further comprising an apparatus for providing optical communications via an optical signal during adverse atmospheric conditions, comprising:

a determiner for determining a change in the maximum achievable bandwidth based on the atmospheric conditions; and

a controller for adjusting the pulse rate of the optical signal to compensate for the change in the maximum achievable bandwidth.

16. The apparatus of claim 15, wherein the maximum achievable bandwidth is determined by the following equation:

BW(τ

)=10<sup>a3+a2 log τ

+a1(log τ

){circumflex over ( 

)}2</sup>

where BW is the maximum achievable bandwidth, τ

is an optical density of the atmospheric conditions, and a1, a2 and a3 are parameters that correspond to various cloud types.

17. The apparatus of claim 16, further comprising means for determining a particular type of atmospheric condition present.

18. The apparatus of claim 17, wherein the optical density is calculated by the following equation:

E(τ

)=E_roe<sup>−

τ

/τ

o</sup>

where E_ro is a measured received energy, and τ

_o is a known optical thickness of the particular type of atmospheric condition.

19. The apparatus of claim 18, wherein the known optical thickness of a cloud containing water molecules is 5.

20. The apparatus of claim 18, wherein the known optical thickness of a cloud containing ice molecules is 13.3.

21. The communications system of claim 2, wherein the terminal is located at one of on a mountain and on a high altitude tether, and the terminal is connected to a user equipment to transceive signals between the satellite and the user equipment.

22. The communications system of claim 1, wherein the information is information received from a media distribution center and the information is entertainment based information.

23. The communications system of claim 1, further comprising a relay transceiver incorporated into an aircraft and interposed between the satellite and at least one terminal for relaying signals between the satellite and the at least one terminal.

24. The communications system of claim 23, wherein the relay transceiver converts signals to a mm band for aircraft to terminal transmission and to optical band for aircraft to satellite transmission.

25. A wireless communications system having at least one satellite and more than one terminal, comprising:

a global positioning system (GPS) receiver contained in a user equipment (UE) for receiving position information pertaining to the terminal;

a star tracking system contained in the at least one satellite for determining position information pertaining to the at least one satellite; and

at least one multiple beam scanning array transceiver contained in a satellite for wirelessly transceiving the information.

26. A multiple beam optical array transceiver, comprising:

at least one receive amplifier for amplifying received optical signals;

at least one transmit amplifier for amplifying optical signals prior to transmission;

at least one micro-electronic mechanical (MEM) mirror for reflecting free-space optical signals;

at least one bi-directional optical coupler connected to the receive amplifier and the transmit amplifier, and associated with the MEM mirror, for transmitting to and receiving from the connected amplifiers an optical signal, and reflecting a free-space optical signal onto and receiving a reflected free-space optical signal from the associated MEM mirror;

at least one holographic aperture for focusing free-space optical signals reflected from the MEM mirror and focusing received free-space optical signals onto the MEM mirror; and

a controller for controlling the aiming of the MEM mirror.

27. A multiple beam optical array antenna, comprising:

at least one receive amplifier for amplifying received optical signals;

at least one transmit amplifier for amplifying optical signals prior to transmission;

at least one bi-directional optical switch bank having a bi-directional fiber optic input and a plurality of fiber optic outputs;

at least one bi-directional optical coupler connected to the receive amplifier, the transmit amplifier, and the input of the switch bank;

at least one holographic aperture connected to the plurality of outputs of the switch bank for receiving and transmitting free-space optical signals; and

a controller for controlling the switch bank.

28. The optical array antenna of claim 27, wherein the switch bank comprises a plurality of optical switches connected in a binary branch configuration connected between the input and the plurality of outputs of the switch bank for receiving an optical signal at the input of the switch bank and controlling a transmission direction of the free-space optical signals through the holographic aperture by directing the optical signal to one of the plurality of outputs according to the switching of the optical switches.

29. The optical array antenna of claim 27, wherein the switch bank comprises a plurality of optical switches connected in a binary branch configuration connected between the input and the plurality of outputs of the switch bank for receiving a free-space optical signal at one of the output ports of the switch bank by controlling a receiving direction of the optical array antenna according to switching of the optical switches.

30. A millimeter wavelength array receive antenna, comprising:

a plurality of array antenna elements each capable of detecting focused millimeter wavelength energy and converting the focused millimeter wavelength energy into electrical signals; and

a millimeter wavelength lens for focusing incident millimeter energy onto said array antenna elements;

wherein said plurality of array antenna elements conform to an array focal contour Of the millimeter wavelength lens.

31. A millimeter wavelength array transmit antenna, comprising:

a plurality of array antenna elements each capable of converting electrical signals into millimeter wavelength energy and emitting the millimeter wavelength energy; and

a millimeter wavelength lens for aiming the emitted millimeter wavelength energy;

wherein said plurality of array antenna elements conform to an array focal contour of the millimeter wavelength lens.

32. The millimeter wavelength array transmit antenna of claim 31, wherein the millimeter wavelength array transmit antenna transmits at steep angles from zenith for minimizing the travel distance of the millimeter wavelength energy.

33. A method of providing communications via an optical signal during adverse atmospheric conditions, comprising the steps of:

determining a change in the maximum achievable bandwidth based on the atmospheric conditions; and

adjusting a pulse rate of the optical signal to compensate for the change in the maximum achievable bandwidth.

34. The method of claim 33, wherein the bandwidth is determined by the following equation:

BW(τ

)=10<sup>a3+a2 log τ

+a1(log τ

){circumflex over ( 

)}2</sup>

where BW is the maximum achievable bandwidth, τ

is an optical density of the atmospheric conditions, and a1, a2 and a3 are parameters that correspond to various cloud types.

35. The apparatus of claim 34, further comprising means for determining a particular type of atmospheric condition present.

36. The apparatus of claim 35, wherein the optical density is calculated by the following equation:

E(τ

)=E_roe<sup>−

τ

/τ

o</sup>

where E_ro is a measured received energy, and τ

_o is a known optical thickness of the particular type of atmospheric condition.

37. The apparatus of claim 36, wherein the known optical thickness of a cloud containing water molecules is 5.

38. The apparatus of claim 36, wherein the known optical thickness of a cloud containing ice molecules is 13.3.

39. An apparatus for providing optical communications via an optical signal during adverse atmospheric conditions, comprising:

a determiner for determining a change in the maximum achievable bandwidth based on the atmospheric conditions; and

a controller for adjusting a pulse rate of the optical signal to compensate for the change in the maximum achievable bandwidth.

40. The apparatus of claim 39, wherein the maximum achievable bandwidth is determined by the following equation:

BW(τ

)=10<sup>a3+a2 log τ

+a1(log τ

){circumflex over ( 

)}2</sup>

where BW is the maximum achievable bandwidth, τ

is an optical density of the atmospheric conditions, and a1, a2 and a3 are parameters that correspond to various cloud types.

41. The apparatus of claim 40, further comprising means for determining a particular type of atmospheric condition present.

42. The apparatus of claim 41, wherein the optical density is calculated by the following equation:

E(τ

)=E_roe<sup>−

τ

/τ

o</sup>

where E_ro is a measured received energy, and τ

_o is a known optical thickness of the particular type of atmospheric condition.

43. The apparatus of claim 42, wherein the known optical thickness of a cloud containing water molecules is 5.

44. The apparatus of claim 42, wherein the known optical thickness of a cloud containing ice molecules is 13.3.

45. A method for setting up a call in a communications system for wireless transceiving of information, comprising the steps of:

transmitting via one of optical and millimeter signals from a first user equipment (UE) a call message to setup a call with a second UE;

receiving at a first satellite the call message from UE1;

transmitting from the first satellite the call message in its coverage area and to other satellites via optical crosslinks;

transmitting via one of optical and millimeter signals by the other satellites the call message in their coverage areas;

receiving at the second UE the call message from one of the satellites and transmitting an acknowledgement the one of the satellites;

routing a call from the first UE to the second UE; and

releasing resources required for the call set up.

46. The method for setting up a call in a communications system for wireless transceiving of information of claim 45, further comprising the step of determining if atmospheric conditions are conducive the transmission of the optical signal and if atmospheric conditions are conducive to the optical signal, then transmitting optical signal, and if atmospheric conditions are not conducive to the optical signal link, then transmitting millimeter signals.

47. A method for setting up a call in a communications system for wireless transceiving of information, comprising the steps of:

transmitting via one of optical and millimeter signals from a first user equipment (UE) a call message to setup a call with a second UE;

receiving at a first satellite the call message from UE1;

determining the location of the second UE;

transmitting via one of optical and millimeter signals to the second UE the call message from a satellite in whose coverage area the second UE is located;

receiving at the second UE the call message from one of the satellites and transmitting an acknowledgement to the one of the satellites;

routing a call from the first UE to the second UE; and

releasing resources required for the call set up.

48. The method for setting up a call in a communications system for wireless transceiving of information of claim 47, further comprising the step of determining if atmospheric conditions are conducive the transmission of the optical signal and if atmospheric conditions are conducive to the optical signal, then transmitting optical signal, and if atmospheric conditions are not conducive to the optical signal link, then transmitting millimeter signals.

49. A method for setting up a call in a communications system for wireless transceiving of information, comprising the steps of:

transmitting via one of optical and millimeter signals from a first user equipment (UE) a call message to setup a call with a second UE;

receiving at a first satellite the call message from UE1;

training a narrow, high-gain, wide-band beam on the first UE;

training a narrow, high-gain, wide-band beam on the second UE;

transmitting via one of optical and millimeter signals the call message to the second UE;

receiving at the second UE the call message from one of the satellites and transmitting an acknowledgement the one of the satellites;

routing a call from the first UE to the second UE; and

releasing resources required for the call set up.

50. The method for setting up a call in a communications system for wireless transceiving of information of claim 49, further comprising the step of determining if atmospheric conditions are conducive the transmission of the optical signal and if atmospheric conditions are conducive to the optical signal, then transmitting optical signal, and if atmospheric conditions are not conducive to the optical signal link, then transmitting millimeter signals.

51. A method for aligning and tracking a call in a communications system for wireless transceiving of information, comprising the steps of:

transmitting from a first user equipment (UE) to a first satellite a log-on message at an assigned mm channel;

receiving at the first satellite the log-on message and determining authorization and identification of the first UE;

determining if atmospheric conditions are conducive to an optical signal link;

if atmospheric conditions are conducive to an optical signal link, transmitting a response in an optical band to the first UE, and if atmospheric conditions are not conducive to an optical signal link, transmitting the response in a millimeter band to the first UE;

receiving at the first UE the response;

setting up a call with a second UE;

determining if atmospheric conditions are conducive to optical signal link;

if atmospheric conditions are conducive to an optical signal link, transmitting the call in an optical band, and if atmospheric conditions are not conducive to an optical signal link, transmitting the call in a millimeter band.