Device, method and computer program for transmitting an information signal comprising several transmit signals

• US 8,031,796 B2
• Filed: 10/25/2006
• Issued: 10/04/2011
• Est. Priority Date: 10/26/2005
• Status: Expired due to Fees

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Heuberger, Albert, Eberlein, Ernst
• Primary Examiner(s): ODOM, CURTIS B
• Application Number:
  US12/091,413
• Publication Number:
  US 20090220022A1
• Time in Patent Office: 1,805 Days
• Field of Search: 375/260, 375/267, 375/299, 375/347, 375/349, 370203-211
• US Class Current: 375/267
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04B 7/18523 Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20
• CPC Class Codes: H04B 7/208 Frequency-division multiple access [FDMA]
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence
• CPC Class Codes: H04L 27/2602 Signal structure

Abstract

A device for transmitting an information signal having several transmit signals has a modulator for generating a first and a second transmit signal. The first transmit signal is transmittable via a first spatial emitter, and the second transmit signal is transmittable via a second spatial emitter. The modulator has an OFDM control stage to load a first group of OFDM carriers with first information to generate the first transmit signal, and to load a second group of OFDM carriers with second information to generate the second transmit signal. The first group of OFDM carriers differs from the second group of OFDM carriers, and the first information differs from the second information. The present invention further provides a corresponding method and a computer program for transmitting an information signal.

Claims

1. A device for transmitting an information signal comprising several transmit signals, comprising:

a modulator for generating a first transmit signal and a second transmit signal, wherein the first transmit signal is transmittable via a first spatial emitter, and wherein the second transmit signal is transmittable via a second spatial emitter,

wherein the modulator comprises;

an OFDM control stage adapted to load a first group of OFDM carriers with first information to generate the first transmit signal, and to load a second group of OFDM carriers with second information to generate the second transmit signal,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and

wherein the first information differs from the second information;

a first antenna adapted to emit the first transmit signal into a first spatially limited area;

a second antenna adapted to emit the second transmit signal into a second spatially limited area,

wherein the first area is defined in that, in the first area, the first transmit signal emitted by the first antenna is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second transmit signal emitted by the second antenna is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the first antenna and the second antenna are adapted so that the first area and the second area overlap;

wherein the OFDM control stage is adapted so that, in the second transmit signal, there is included at least one commonly used group of OFDM carriers also included in the first transmit signal;

wherein the OFDM control stage is further adapted to load the commonly used group of OFDM carriers in the first transmit signal and in the second transmit signal with the same common information;

wherein the OFDM control stage is adapted to generate the first transmit signal so that, in the first transmit signal, there is included a group of OFDM carriers that is inactive in the second transmit signal; and

wherein the OFDM control stage is adapted to generate the second transmit signal so that, in the second transmit signal, there is included a group of OFDM carriers that is inactive in the first transmit signal.

2. The device of claim 1, wherein the first antenna and the second antenna are adapted so that the first area and the second area do not overlap, and

wherein the OFDM control stage is adapted so that the second transmit signal comprises at least one commonly used group of OFDM carriers also included in the first transmit signal, and

wherein the OFDM control stage is further adapted to load the commonly used group of OFDM carriers in the first transmit signal with other information than in the second transmit signal.

3. The device of claim 1, wherein the OFDM control stage is adapted to selectively load with the first information or deactivate a group of OFDM carriers from the total set of OFDM carriers that are usable both for the generation of the first transmit signal and for the generation of the second transmit signal, when generating the first transmit signal, and

to selectively load with the second information or deactivate a further group of OFDM carriers from the total set of OFDM carriers that are usable both for the generation of the first transmit signal and for the generation of the second transmit signal, when generating the second transmit signal.

4. The device of claim 1, wherein the OFDM control stage is adapted to receive a plurality of information signals and to selectively associate groups of OFDM carriers with the information signals when generating the first transmit signal, and to selectively associate groups of OFDM carriers with the information signals when generating the second transmit signal,

wherein the modulator is adapted to modulate an OFDM carrier with data contents of an associated information signal, and

wherein the OFDM control stage is further adapted to deactivate a group of OFDM carriers with which no information signal is associated.

5. The device of claim 1, wherein the OFDM control stage is adapted to deactivate a group of OFDM carriers by the OFDM control stage setting an amplitude associated with the deactivating OFDM carrier to zero.

6. The device of claim 1, wherein the OFDM control stage comprises a distribution matrix adapted to receive at least two information signals, and to selectively load the first group of OFDM carriers with the first information signal when generating the first transmit signal, and to selectively load the second group of OFDM carriers with the second information signal,

and to selectively load the first group of OFDM carriers with the first information signal when generating the second transmit signal, and to selectively load the second group of OFDM carriers with the second information signal.

7. The device of claim 6, wherein the distribution matrix is a complete distribution matrix adapted to receive more than two information signals, and to associate the received information signals in an arbitrarily selectable way with predetermined groups of OFDM carriers when generating the first transmit signal, and to associate the information signals in an arbitrarily selectable way with predetermined groups of OFDM carriers when generating the second transmit signals.

8. The device of claim 1, wherein the first information and the second information represent different programs of a digital broadcasting emission.

9. The device of claim 1, wherein the first information and the second information comprise voice signals in different languages.

10. The device of claim 1, adapted for a use in a satellite.

11. The device of claim 1, wherein the device is adapted to be part of a satellite, wherein the first spatial emitter is a first satellite antenna for emitting the first transmit signal as a spot beam,

wherein the second spatial emitter is a second satellite antenna for emitting the second transmit signal as a spot beam,

wherein the first spot beam is spatially distinguishable from the second spot beam, and

wherein the OFDM control stage is adapted to generate the first transmit signal as an OFDM-modulated signal, to generate the second transmit signal as an OFDM-modulated signal, to selectively load individual OFDM segments in the first OFDM signal with information or deactivate them, and to selectively load individual OFDM segments in the second transmit signal with information or deactivate them.

12. The device of claim 11, wherein the OFDM control stage is adapted to allow that an OFDM segment deactivated in the second transmit signal is active and loaded with information in the first transmit signal.

13. A method for transmitting an information signal comprising several transmit signals, wherein the first transmit signal is transmittable via a first spatial emitter into a first spatially limited area, and wherein the second transmit signal is transmittable via a second spatial emitter into a second spatially limited area, comprising:

loading a first group of OFDM carriers with the first information using a hardware or a computer to obtain the first transmit signal by modulation of the first group of OFDM carriers with the first information; and

loading a second group of OFDM carriers with the second information using a hardware or a computer to generate the second transmit signal by modulation of the second group of OFDM carriers with the second information,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and wherein the first information differs from the second information,

wherein the first area is defined in that, in the first area, the first transmit signal emitted by the first spatial emitter is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second transmit signal emitted by the second spatial emitter is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the first area and the second area overlap;

wherein in the second transmit signal, there is included at least one commonly used group of OFDM carriers also included in the first transmit signal;

wherein the commonly used group of OFDM carriers is loaded with the same common information in the first transmit signal and in the second transmit signal;

wherein in the first transmit signal, there is included a group of OFDM carriers that is inactive in the second transmit signal; and

wherein in the second transmit signal, there is included a group of OFDM carriers that is inactive in the first transmit signal.

14. A non-transitory computer-readable medium comprising a computer program for performing a method for transmitting an information signal comprising several transmit signals, wherein the first transmit signal is transmittable via a first spatial emitter into a first spatially limited area, and wherein the second transmit signal is transmittable via a second spatial emitter into a second spatially limited area, the method comprising:

loading a first group of OFDM carriers with the first information to obtain the first transmit signal by modulation of the first group of OFDM carriers with the first information; and

loading a second group of OFDM carriers with the second information to generate the second transmit signal by modulation of the second group of OFDM carriers with the second information,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and wherein the first information differs from the second information,

wherein the first area is defined in that, in the first area, the first transmit signal emitted by the first spatial emitter is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second transmit signal emitted by the second spatial emitter is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the first area and the second area overlap;

wherein in the second transmit signal, there is included at least one commonly used group of OFDM carriers also included in the first transmit signal;

wherein the commonly used group of OFDM carriers is loaded with the same common information in the first transmit signal and in the second transmit signal;

wherein in the first transmit signal, there is included a group of OFDM carriers that is inactive in the second transmit signal; and

wherein in the second transmit signal, there is included a group of OFDM carriers that is inactive in the first transmit signal,

when the computer program runs on a computer.

15. A device for transmitting an information signal comprising several transmit signals, comprising:

a modulator for generating a first transmit signal and a second transmit signal, wherein the first transmit signal is transmittable via an antenna arrangement, and wherein the second transmit signal is transmittable via the antenna arrangement,

wherein the modulator comprises;

an OFDM control stage designed to load a first group of OFDM carriers with first information to generate the first transmit signal, and to load a second group of OFDM carriers with second information to generate the second transmit signal,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and

wherein the first information differs from the second information;

an antenna arrangement designed to emit the first transmit signal into a first spatially limited area, and to emit the second transmit signal into a second spatially limited area,

wherein the first area is defined in that, in the first area, the first transmit signal emitted by the antenna arrangement is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second transmit signal emitted by the antenna arrangement is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the antenna arrangement is designed so that the first area and the second area overlap;

wherein the OFDM control stage is designed so that, in the second transmit signal, there is contained at least one commonly used group of OFDM carriers also contained in the first transmit signal;

wherein the OFDM control stage is further designed to load the commonly used group of OFDM carriers in the first transmit signal and in the second transmit signal with the same common information;

wherein the OFDM control stage is designed to generate the first transmit signal so that, in the first transmit signal, there is contained a group of OFDM carriers that is inactive in the second transmit signal; and

wherein the OFDM control stage is designed to generate the second transmit signal so that, in the second transmit signal, there is contained a group of OFDM carriers that is inactive in the first transmit signal.

16. A method for transmitting an information signal comprising several transmit signals, wherein the first transmit signal is transmittable into a first spatially limited area, and wherein the second transmit signal is transmittable into a second spatially limited area, comprising:

loading a first group of OFDM carriers with the first information using a hardware or a computer to obtain the first transmit signal by modulation of the first group of OFDM carriers with the first information; and

loading a second group of OFDM carriers with the second information using a hardware or a computer to generate the second transmit signal by modulation of the second group of OFDM carriers with the second information,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and wherein the first information differs from the second information,

wherein the first area is defined in that, in the first area, the first emitted transmit signal is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second emitted transmit signal is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the first area and the second area overlap;

wherein in the second transmit signal, there is contained at least one commonly used group of OFDM carriers also contained in the first transmit signal;

wherein the commonly used group of OFDM carriers is loaded with the same common information in the first transmit signal and in the second transmit signal;

wherein in the first transmit signal, there is contained a group of OFDM carriers that is inactive in the second transmit signal; and

wherein in the second transmit signal, there is a contained a group of OFDM carriers that is inactive in the first transmit signal.

17. A non-transitory computer-readable medium comprising a computer program for performing a method for transmitting an information signal comprising several transmit signals, wherein the first transmit signal is transmittable into a first spatially limited area, and wherein the second transmit signal is transmittable into a second spatially limited area, comprising:

loading a first group of OFDM carriers with the first information to obtain the first transmit signal by modulation of the first group of OFDM carriers with the first information; and

loading a second group of OFDM carriers with the second information to generate the second transmit signal by modulation of the second group of OFDM carriers with the second information,

wherein the first group of OFDM carriers differs from the second group of OFDM carriers, and wherein the first information differs from the second information,

wherein the first area is defined in that, in the first area, the first emitted transmit signal is receivable with a field strength larger than a predetermined first threshold field strength, and

wherein the second area is defined in that, in the second area, the second emitted transmit signal is receivable with a field strength larger than a predetermined second threshold field strength,

wherein the first area and the second area overlap;

wherein in the second transmit signal, there is contained at least one commonly used group of OFDM carriers also contained in the first transmit signal;

wherein the commonly used group of OFDM carriers is loaded with the same common information in the first transmit signal and in the second transmit signal;

wherein in the first transmit signal, there is contained a group of OFDM carriers that is inactive in the second transmit signal; and

wherein in the second transmit signal, there is contained a group of OFDM carriers that is inactive in the first transmit signal.