COMMUNICATION APPARATUS AND COMMUNICATION SYSTEM

• US 20110206155A1
• Filed: 07/02/2009
• Published: 08/25/2011
• Est. Priority Date: 10/30/2008
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Kihira, Kazunari, Sogabe, Yasushi, Fujimura, Akinori
• Granted Patent: US 8,542,785 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04B 7/18563 Arrangements for interconnecting multiple systems data switching networks H04L12/00
• CPC Class Codes: H04W 84/06 Airborne or Satellite Networks space-based or airborne stations H04B7/185

Abstract

A communication apparatus that can suppress an increase in circuit size and reduce influence of interference, includes reception array antenna elements, a reception DBF network that generates a reception beam signal for forming M reception beams using a reception signal, and reception FBs that generate frequency split reception beam signals obtained by frequency-splitting the reception beam signal. The communication apparatus includes an interference-source detecting unit that stores, for each reception beam, an interference candidate beam area estimated based on an initial reception beam characteristic, calculates, based on the frequency split reception beam signals, a reception spectrum, and calculates, based on the reception spectrum and a reception spectrum of a reception beam to the interference candidate beam area, an interference source area. The reception DFB network generates a reception beam signal to perform null formation in the direction of the interference source area.

Claims

1. A communication apparatus comprising:

a reception array antenna including N (N is a natural number) array antenna elements;

a reception-beam forming unit that generates a reception beam signal for forming M (M is a natural number) reception beams in different beam areas using a reception signal for each of the array antenna elements according to digital beam formation processing; and

a reception filter bank that generates frequency split reception beam signals obtained by frequency-splitting the reception beam signal, wherein

the communication apparatus comprises an interference-source detecting unit that stores, for each reception beam, an interference candidate beam area as a beam area that is estimated based on an initial reception beam characteristic set in advance and interferes with the reception beam, calculates, based on the frequency split reception beam signals, a reception spectrum for each reception beam, and calculates, based on the reception spectrum for each reception beam and a reception spectrum of a reception beam directed to the interference candidate beam area, for each combination of a reception beam and a frequency, an interference source area as a beam area to be an interference source, and

the reception-beam forming unit generates, for each combination of a reception beam and a frequency, the reception beam signal to perform null formation in a direction of the interference source area.

2. The communication apparatus according to claim 1, wherein the reception-beam forming unit extracts a pilot signal included in the reception signal and forms, based on the extracted pilot signal, a reception beam to thereby perform directivity control.

5. The communication apparatus according to claim 1, wherein the interference-source detecting unit sets, as an intra-area transmission signal, a signal transmitted from a target beam area as an area covered by a reception beam, sets, based on the initial reception beam characteristic, for each combination of a reception beam and a frequency, a relational expression of an intra-area transmission signal corresponding to the reception beam, an intra-area transmission signal of the reception beam directed to the interference candidate beam area, and an estimated value of a spectrum of a reception signal of the reception beam and sets relational expressions, which are set for different combinations, as simultaneous equations, substitutes reception spectra of the same combination in the estimated value to calculate, based on the simultaneous equations after the substitution, an intra-area transmission signal, and calculates, for each reception beam, based on an intra-area transmission signal in a beam area estimated in advance to interfere with the reception beam signal, an interference source area for each the combination.

6. The communication apparatus according to claim 1, wherein the interference-source detecting unit sets, when a reception spectrum of the reception beam directed to the interference candidate beam area is equal to or larger than a predetermined threshold, the interference candidate beam area as an interference source area.

7. The communication apparatus according to claim 1, further comprising:

an A/D conversion unit that analog-digital converts a signal received by the reception array antenna and outputs a digital signal; and

an AGC unit that adjusts, based on the digital signal, a level of a signal input to the A/D conversion unit, wherein

the communication apparatus sets the reception signal as the digital signal.

8. The communication apparatus according to claim 1, further comprising:

a transmission array antenna including transmission array antenna elements; and

a transmission-beam forming unit that generates, using a transmission signal for each of the transmission array antenna elements, a transmission beam signal for forming M (M is a natural number) transmission beams to different beam areas according to digital beam formation processing, wherein

the transmission-beam forming unit generates a transmission beam signal to reduce occurrence of leakage to the interference source area.

9. A communication system comprising:

an artificial satellite mounted with the communication apparatus according to claim 1;

a user terminal that performs radio communication with the communication apparatus; and

a ground station that transmits, based on position and posture of the artificial satellite, beam information including an irradiation direction of a reception beam to the artificial satellite, wherein

the artificial satellite forms, based on the beam information, a reception beam.

11. The communication system according to claim 9, wherein the communication system adopts a CDMA system and shares a frequency with a radio system that adopts a multiple access system other than the CDMA system.

12. The communication system according to claim 9, wherein the communication system adopts a multiple access system other than a CDMA system and shares a frequency with a radio system that adopts the CDMA system.

13. The communication system according to claim 11, wherein

the communication system divides the shared frequency band into a plurality of divided frequency bands and allocates the divided frequency bands to a beam area covered by the communication apparatus of the artificial satellite such that different divided frequency bands are used in beam areas adjacent to one another, and

the radio system uses, in the beam area, a frequency different from the divided frequency band allocated to the beam area.

14. The communication system according to claim 13, wherein the communication system sets, as one group, beam areas to which the different divided frequency bands are allocated and repeatedly arranges groups such that allocated divided frequency bands of the beam areas adjacent to one another are different.

3. A communication apparatus comprising:

a reception array antenna including N (N is a natural number) array antenna elements;

a reception filter bank that generates frequency split signals obtained by frequency-splitting a reception signal for each of the array antenna elements; and

a reception-beam forming unit that generates frequency split reception beam signals for forming M (M is a natural number) reception beams in different beam areas using the frequency split signals according to digital beam formation processing, wherein

the communication apparatus comprises an interference-source detecting unit that stores, for each reception beam, an interference candidate beam area as a beam area that is estimated based on an initial reception beam characteristic set in advance and interferes with the reception beam, calculates, based on the frequency split reception beam signals, a reception spectrum for each reception beam, and calculates, based on the reception spectrum for each reception beam and a reception spectrum of a reception beam directed to the interference candidate beam area, for each combination of a reception beam and a frequency, an interference source area as a beam area to be an interference source, wherein

the reception-beam forming unit generates, for each combination of a reception beam and a frequency, the reception beam signal to perform null formation in a direction of the interference source area.

4. The communication apparatus according to claim 3, wherein the reception-beam forming unit extracts a pilot signal included in the frequency split signal and forms, based on the extracted pilot signal, a reception beam to thereby perform directivity control.

15. The communication apparatus according to claim 3, wherein the interference-source detecting unit sets, as an intra-area transmission signal, a signal transmitted from a target beam area as an area covered by a reception beam, sets, based on the initial reception beam characteristic, for each combination of a reception beam and a frequency, a relational expression of an intra-area transmission signal corresponding to the reception beam, an intra-area transmission signal of the reception beam directed to the interference candidate beam area, and an estimated value of a spectrum of a reception signal of the reception beam and sets relational expressions, which are set for different combinations, as simultaneous equations, substitutes reception spectra of the same combination in the estimated value to calculate, based on the simultaneous equations after the substitution, an intra-area transmission signal, and calculates, for each reception beam, based on an intra-area transmission signal in a beam area estimated in advance to interfere with the reception beam signal, an interference source area for each the combination.

16. The communication apparatus according to claim 3, wherein the interference-source detecting unit sets, when a reception spectrum of the reception beam directed to the interference candidate beam area is equal to or larger than a predetermined threshold, the interference candidate beam area as an interference source area.

17. The communication apparatus according to claim 3, further comprising:

an A/D conversion unit that analog-digital converts a signal received by the reception array antenna and outputs a digital signal; and

an AGC unit that adjusts, based on the digital signal, a level of a signal input to the A/D conversion unit, wherein

the communication apparatus sets the reception signal as the digital signal.

18. The communication apparatus according to claim 3, further comprising:

a transmission array antenna including transmission array antenna elements; and

a transmission-beam forming unit that generates, using a transmission signal for each of the transmission array antenna elements, a transmission beam signal for forming M (M is a natural number) transmission beams to different beam areas according to digital beam formation processing, wherein

the transmission-beam forming unit generates a transmission beam signal to reduce occurrence of leakage to the interference source area.

19. A communication system comprising:

an artificial satellite mounted with the communication apparatus according to claim 3;

a user terminal that performs radio communication with the communication apparatus; and

a ground station that transmits, based on position and posture of the artificial satellite, beam information including an irradiation direction of a reception beam to the artificial satellite, wherein

the artificial satellite forms, based on the beam information, a reception beam.

20. The communication system according to claim 19, wherein the communication system adopts a CDMA system and shares a frequency with a radio system that adopts a multiple access system other than the CDMA system.

21. The communication system according to claim 19, wherein the communication system adopts a multiple access system other than a CDMA system and shares a frequency with a radio system that adopts the CDMA system.

10. A communication system comprising:

an artificial satellite mounted with a communication apparatus including;

a reception array antenna including N (N is a natural number) array antenna elements;

a reception-beam forming unit that generates a reception beam signal for forming M (M is a natural number) reception beams in different beam areas using a reception signal for each of the array antenna elements according to digital beam formation processing; and

a reception filter bank that generates frequency split reception beam signals obtained by frequency-splitting the reception beam signal;

a user terminal that performs radio communication with the communication apparatus; and

a ground station that transmits, based on position and posture of the artificial satellite, beam information including an irradiation direction of a reception beam to the artificial satellite, wherein

the communication apparatus of the artificial satellite transmits the frequency split reception beam signals to the ground station,

the ground station stores, for each reception beam, an interference candidate beam area as a beam area that is estimated based on an initial reception beam characteristic set in advance and interferes with the reception beam, calculates, based on the frequency split reception beam signals, a reception spectrum for each reception beam, calculates, based on the reception spectrum for each reception beam and a reception spectrum of a reception beam directed to the interference candidate beam area, for each combination of a reception beam and a frequency, an interference source area as a beam area to be an interference source, calculates a weight value for performing null formation in a direction of the interference source area for each the combination, and transmits the weight value to the artificial satellite mounted with the communication apparatus, and

the communication apparatus of the artificial satellite forms, based on the weight value, a reception beam.

22. The communication system according to claim 10, wherein the communication system adopts a CDMA system and shares a frequency with a radio system that adopts a multiple access system other than the CDMA system.

23. The communication system according to claim 10, wherein the communication system adopts a multiple access system other than a CDMA system and shares a frequency with a radio system that adopts the CDMA system.

24. The communication system according to claim 23, wherein

the communication system divides the shared frequency band into a plurality of divided frequency bands and allocates the divided frequency bands to a beam area covered by the communication apparatus of the artificial satellite such that different divided frequency bands are used in beam areas adjacent to one another, and

the radio system uses, in the beam area, a frequency different from the divided frequency band allocated to the beam area.

25. The communication system according to claim 24, wherein the communication system sets, as one group, beam areas to which the different divided frequency bands are allocated and repeatedly arranges groups such that allocated divided frequency bands of the beam areas adjacent to one another are different.