Telecommunications satellite channelizer

• US 6,317,583 B1
• Filed: 07/25/1997
• Issued: 11/13/2001
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Wolcott, James L., Faris, Alan E.
• Primary Examiner(s): Chang, Vivian
• Assistant Examiner(s): APPIAH, CHARLES NANA
• Application Number:
  US08/900,495
• Time in Patent Office: 1,572 Days
• Field of Search: 455/12.1, 455/13.1, 455/13.2, 455/13.3, 455/427, 455/428, 370/316, 370/319, 370/325, 370/360, 342/352, 342/353
• US Class Current: 455/12.1
• CPC Class Codes: H04B 7/18539 Arrangements for managing radio, resources, i.e. for establishing or releasing a connection
• CPC Class Codes: H04B 7/2045 SS-FDMA, FDMA satellite switching

Abstract

A telecommunications satellite channelizer (170) is provided for mapping RF signals between feeder links (160-162) and mobile link beams (210-212) based on a predefined frequency plan (FIGS. 7 and 8). The mobile link beams (240) define a coverage area (242) of a satellite (10). Each feeder link and mobile link beam comprises a plurality of feeder subbands and mobile subbands grouped to form feeder link channels (216-238) and mobile link channels (244-255). The channelizer (170) includes at least one feeder lead carrying a feeder link signal (160-162) associated with a ground station (14 and 16). A feeder link distribution network (175) is connected to the feeder leads and maps RF signals in the feeder links (160-162) onto a plurality of distribution leads as divided feeder signals. Channel multiplexers (182-184) are connected to the distribution leads. Each channel multiplexer (182) includes a set of band pass filters (190-201), each of which passes RF signals in a subset of feeder subbands corresponding to a single feeder channel in order to map a mobile link channel (244) and a feeder link channel (216) onto one another based on a predefined frequency plan. The channelizer (170) groups or multiplexes signals from a plurality of feeders into each beam. Fixed local oscillator up converters shift each composite mobile channel to a common band allocated to all beams. The frequency plan is defined such that beam handovers and ground station handovers may be performed without a need for at least one of switching, retuning and resynchronization of the telecommunications satellite and the mobile terminal.

Claims

1. A telecommunications satellite channelizer for mapping RF signals between feeder links and mobile link beams based on predefined frequency plans, the mobile link beams defining a coverage area of a satellite, each feeder link and mobile link beam comprising a plurality of feeder frequency subbands and mobile frequency subbands, respectively, carrying RF signals between ground stations and the satellite and between the satellite and mobile terminals, respectively, wherein mobile frequency subbands are grouped to form mobile link channels and wherein feeder frequency subbands are grouped to form feeder link channels, said channelizer comprising:

at least one feeder lead, each feeder lead carrying a feeder link signal associated with a ground station, said feeder link signal having a frequency spectrum divided into a plurality of said feeder link channels;

a feeder link distribution network connected to said at least one feeder lead mapping RF signals separately between each feeder link signal and a corresponding plurality of processing channel leads;

at least one channel multiplexer mapping a mobile link channel and a feeder link channel onto one another based on one of a predefined set of frequency plans, said multiplexer mapping at least first and second feeder link channels from first and second feed links, onto separate corresponding first and second mobile link channels, respectively, in a single mobile link beam, wherein said first and second feeder link channels include separate, non-overlapping feeder frequency subbands, and wherein said first and second mobile link channels include separate, non-overlapping mobile frequency subbands, said channel multiplexer including a set of band pass filters connected to a processing channel lead, each filter passing RF signals for a subset of subbands associated with a single feeder link channel, said multiplexer mapping mobile and feeder link channels on to one another based on predefined frequency plans that enable ground stations to perform mobile link beam handovers without a need for at least one of switching, retuning and resynchronizing the telecommunications satellite; and

converters translating RF signals between frequency spectrums of subbands of feeder link channels and mobile link channels.

2. A telecommunications satellite channelizer according to claim 1, further comprising first and second channel multiplexers passing first and second feeder link channels based on first and second predefined frequency plans.

3. A telecommunications satellite channelizer according to claim 1, wherein each channel multiplexer includes at least four band pass filters, first and second band pass filters passing corresponding feeder link channels to a first mobile link beam, third and fourth band pass filters passing corresponding feeder link channels to second and third mobile link beams, respectively.

4. A telecommunications satellite channelizer according to claim 1, further comprising multiple channel multiplexers, each channel multiplexer including multiple band pass filters cooperating to pass from multiple feeder links consecutive feeder link channels in a predetermined order based on a corresponding predefined frequency plan.

5. A telecommunications satellite channelizer according to claim 1, wherein each channel multiplexer includes four band pass filters to pass four feeder link channels which are uniquely mapped to four corresponding mobile link channels in one beam.

6. A telecommunications satellite channelizer according to claim 1, further comprising a plurality of summers, each summer being connected to associated band pass filters for combining a subset of feeder link channels to form a subset of RF signals associated with passed feeder link channels, a corresponding converter translating said subset of RF signals to said frequency spectrum of corresponding mobile link channels.

7. A telecommunications satellite channelizer, according to claim 1, further comprising fixed local oscillators driving said converters, wherein a single local oscillator drives a group of converters associated with a group of beams.

8. A telecommunications satellite channelizer according to claim 1, further comprising an automatic level control adjusting the amplitude of said feeder link signal based on a pilot tone in said feeder link signal.

9. A telecommunications satellite channelizer according to claim 1, wherein said converters further comprise a down converter translating a frequency of said feeder link signal from a K-band frequency spectrum to an intermediate frequency spectrum upstream of said feeder link distribution network, and an up converter translating RF signals at said intermediate frequency spectrum to an L-band frequency spectrum.

10. A telecommunications satellite channelizer according to claim 1, further comprising:

at least first and second feeder input leads receiving first and second feeder link signals from first and second ground stations;

at least first and second power dividers, connected to said first and second feeder input leads, respectively, distributing said first and second feeder link signals among first and second pluralities of processing channel leads, wherein at least one channel multiplexer includes first and second band pass filters passing a first feeder link channel from said first feeder link signal and a second feeder link channel from said second feeder link signal.

11. A telecommunications satellite channelizer according to claim 1, further comprising:

at least two feeder input leads receiving two feeder link signals, said feeder link distribution network including at least two power dividers separately supplying said at least two feeder link signals to at least two band pass filters in one channel multiplexer, each of said at least two band pass filters passing a feeder link channel from a corresponding feeder link signal based on a frequency plan of an associated mobile link beam.

12. A telecommunications satellite channelizer according to claim 1, further comprising:

at least two feeder input leads receiving at least two feeder link signals;

a summer combining said at least two feeder link signals to form a combined feeder link signal supplied to said feeder link distribution network; and

switches for selectively connecting and disconnecting said feeder link signals from said summer.

13. A telecommunications satellite channelizer, according to claim 1, further comprising:

summers for combining outputs of said bandpass filters; and

a plurality of switches for selectively connecting and disconnecting band pass filters and outputs to said summers.

14. A telecommunications satellite channelizer according to claim 1, wherein said feeder link distribution network and channel multiplexer cooperate such that feeder channels in a first common frequency range from multiple feeder links are mapped to mobile channels in a second common frequency range in multiple mobile link beams.

15. A telecommunications satellite channelizer according to claim 1, wherein said channel multiplexer maps first and second mobile link channels from adjacent feeder channels to a single beam.

16. A telecommunications satellite channelizer according to claim 1, wherein said channel multiplexer maps feeder channels from a single feeder link to different mobile channel locations in adjacent beams.

17. A telecommunications satellite channelizer according to claim 1, wherein said multiple channel multiplexers map all feeder channels in a predetermined frequency range from a number of feeder links into a number of beams, said number of feeder channels in said predetermined frequency range from a single feeder link equalling said number of available channels in a beam.

18. A telecommunications satellite channelizer according to claim 1, wherein said set of frequency plans includes more than one frequency plan and fewer frequency plans than the number of mobile link beams.

19. A telecommunications satellite channelizer according to claim 1, wherein a number of feeder link channels in one feeder link equals the number of mobile link beams.

20. A telecommunications satellite channelizer according to claim 1, wherein a mobile link beam includes at least two mobile link channels mapped from at least two associated feeder link channels in one feeder link.

21. A telecommunications satellite channelizer according to claim 1, wherein a frequency range of said feeder links differs from a frequency range of said mobile link beams.

22. A method of mapping RF signals, in a telecommunications satellite channelizer, between ground stations and mobile terminals, said method comprising the steps of:

transmitting and receiving RF signals in feeder links to and from ground stations, each feeder link having a frequency spectrum divided into feeder channels, each feeder channel in a feeder link having a different frequency range;

transmitting and receiving RF signals in mobile link beams to and from mobile terminals, each mobile link beam having a frequency spectrum divided into multiple mobile link channels, each mobile link channel in a mobile link beam having a different frequency range;

defining at least one frequency plan, identifying a one-to-one correlation between feeder channels and mobile link channels;

assigning a frequency plan to each mobile link beam; and

defining at least one frequency plan such that at least two mobile link channels in a single mobile link beam are mapped to a single feeder link.

23. A method according to claim 22, further comprising the steps of:

transmitting and receiving RF signals over multiple feeder links to and from multiple ground stations; and

based on a first frequency plan mapping at least one channel each from first and second feeder links onto first and second channels in a first mobile link beam.

24. A method according to claim 22, wherein the frequency plans are defined such that the number of feeder channels in a feeder link equals the number of mobile link beams.

25. A method according to claim 22, wherein the frequency plans are defined such that first and second feeder channels from first and second feeder links, respectively, are mapped to mobile channels from first and second mobile link beams, respectively, said first and second feeder channels having a common frequency range.

26. A method according to claim 22, wherein the frequency plans are defined such that the mobile link channels maintain the same relation to one another as the relation of associated feeder channels relative to one another regardless of the feeder link from which the feeder channel originated.

27. A method according to claim 22, wherein the frequency plans are defined such that first and second mobile link channels in a single mobile link beam are mapped from adjacent feeder channels in a single feeder link.

28. A method according to claim 22, further comprising the steps of defining different frequency plans for adjacent mobile link beams.

29. A method according to claim 22, further comprising the steps of:

mapping first through fourth mobile link channels of successive frequencies in a first mobile link beam to first through fourth feeder channels of consecutive frequency, said first and fourth feeder channels being from a first feeder link, said second feeder channel being from a second feeder link and said third feeder channel being from a third feeder link.

30. A method according to claim 22, further comprising the steps of:

transmitting and receiving RF signals over at least two feeder links from at least two ground stations; and

mapping channels from each of said first and second feeder links separately and independent of one another through the channelizer according to first and second frequency plans.

31. A method according to claim 22, wherein said assigning step assigns a different frequency plan to all adjacent beams.

32. A method according to claim 22, wherein said assigning step includes the step of assigning different frequency plans to adjacent mobile link beams and assigning a common frequency plan to mobile link beams remotely located from one another.

33. A method according to claim 22, further comprising the step of assigning a first frequency range to said feeder links and a second frequency range to said mobile link beams, said first and second frequency ranges differing from one another.