Beam automatic selection switching method in multi-beam satellite communication system and apparatus for same

• US 6,421,526 B1
• Filed: 08/27/1996
• Issued: 07/16/2002
• Est. Priority Date: 02/06/1996
• Status: Expired due to Fees

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Banno, Kozo
• Primary Examiner(s): HUNTER, DANIEL S
• Application Number:
  US08/703,907
• Time in Patent Office: 2,149 Days
• Field of Search: 455/427, 455/425, 455/428, 455/429, 455/430, 455/12.1, 455/13.1, 455/507, 455/517, 455/524, 455/456, 455/457, 455/436, 455/440
• US Class Current: 455/13.1
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 3/24 varying the orientation by switching energy from one active radiating element to another, e.g. for beam switching
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/06966 using beam correspondence; using channel reciprocity, e.g. downlink beam training based on uplink sounding reference signal [SRS]
• CPC Class Codes: H04B 7/18541 for handover of resources
• CPC Class Codes: H04B 7/2041 Spot beam multiple access

Abstract

A position-beam correspondence data table in which a plurality of areas on the ground and beams from the communication satellite each covering each area are correlated to each other is previously prepared, a current position of the mobile satellite communication terminal is computed by a position computing means at a point of time when the mobile satellite communication terminal is not executing communications such as when a power for the mobile satellite communication terminal is turned ON, or when a prespecified key is pressed down, a beam corresponding to the computed current position is red out from said position-beam correspondence data table, a beam to be used in the area including the current position is decided, and a beam switch request command for switching to this beam is transmitted to the communication satellite.

Claims

1. An automatic beam switching method in a multi-beam satellite communication system comprising the steps of:

storing a plurality of ground positions of a plurality of beams of said multi-beam satellite communication system in a position-beam correspondence table;

computing a first position of a mobile satellite communication terminal;

selecting a first beam of said plurality of beams by referencing said position-beam correspondence table, utilizing said first position of said mobile satellite communication terminal as an index into said position-beam correspondence table; and

transmitting a first beam switching request to said multi-beam satellite communication system for switching to said selected first beam.

2. An automatic beam switching method in a multi-beam satellite communication system, comprising the steps of:

storing a plurality of ground positions of a plurality of beams of said multi-beam satellite communication system in a position-beam correspondence table;

computing a first position of a mobile satellite communication terminal;

selecting a first beam by referencing said position-beam correspondence table, utilizing said first position of said mobile satellite communication terminal as an index into said position-beam correspondence table;

transmitting a first beam switching request to said multi-beam satellite communication system to switch said communication system to said selected beam;

storing a plurality of angular directions corresponding to a plurality of adjacent beams in a direction-beam correspondence table;

assessing a signal quality of a signal received from said multi-beam satellite communication system;

selecting a second beam by referencing said direction-beam correspondence table when said signal quality does not exceed a predetermined threshold; and

transmitting a second beam switching request to said multi-beam satellite communication system for switching to said second beam when said second beam has been selected.

3. An automatic beam switching method in a multi-beam satellite communication system according to claim 2 wherein the step of storing a plurality of angular directions corresponding to a plurality of adjacent beams in a direction-beam correspondence table further comprises:

transmitting a current position of said mobile satellite communication terminal from said multi-beam satellite communication system to an earth station;

generating said plurality of angular directions corresponding to said plurality of adjacent beams;

transmitting said plurality of angular directions from said earth station to said multi-beam satellite communication system; and

transmitting said plurality of angular directions from said multi-beam satellite communication system to said mobile satellite communication terminal.

4. An automatic beam switching method in a multi-beam satellite communication system, comprising the steps of:

storing a plurality of ground positions of a plurality of beams of said multi-beam satellite communication system in a position-beam correspondence table;

computing a first position of a mobile satellite communication terminal;

selecting a first beam by referencing said position-beam correspondence table, utilizing said first position of said mobile satellite communication terminal as an index into said position-beam correspondence table;

transmitting a first beam switching request to said multi-beam satellite communication system to switch said communication system to said selected beam;

storing a plurality of angular directions corresponding to a plurality of adjacent beams in a direction-beam correspondence table;

assessing a signal quality of a signal received from said multi-beam satellite communication system;

selecting a second beam by referencing said direction-beam correspondence table when said signal quality does not exceed a predetermined threshold; and

transmitting a second beam switching request to said multi-beam satellite communication system for switching said communication system to said second beam when said second beam has been selected.

5. An automatic beam switching method in a multi-beam satellite communication system according to claim 4 wherein the step of storing a plurality of angular directions corresponding to a plurality of adjacent beams in a direction-beam correspondence table further comprises:

transmitting a current position of said mobile satellite communication terminal from a multi-beam satellite to an earth station;

generating said plurality of angular directions corresponding to said Plurality of adjacent beams;

transmitting said plurality of angular directions from said earth station to said multi-beam satellite communication system; and

transmitting said plurality of angular directions from said multi-beam satellite communication system to said mobile satellite communication terminal.

6. An automatic beam switching apparatus in a multi-beam satellite communication system comprising:

a position computing means for computing a first position of a mobile satellite communication terminal;

a position-beam correspondence table having a plurality of stored positions that correspond to a plurality of adjacent beams; and

a beam switching means for selecting a first beam by referencing said position-beam correspondence table using said computed first position of said mobile satellite communication terminal.

7. An automatic beam switching apparatus in a multi-beam satellite communication system comprising:

position computing means for computing a current position of a mobile satellite communication terminal;

direction detection means for detecting a direction of movement of said mobile satellite communication terminal;

a position-beam correspondence table having a plurality of stored positions that correspond to a plurality of adjacent beams;

means for selecting a first beam from said position-beam correspondence table using said computed current position of said mobile satellite communication terminal;

a direction-beam correspondence table having a plurality of stored angular directions that correspond to a plurality of adjacent beams;

a direction-beam correspondence table generating means for generating said direction-beam correspondence table;

a signal quality assessing means for assessing a signal quality of a signal received from said multi-beam satellite communication system using said selected first beam; and

a beam switching means for selecting a second beam by referencing said direction-beam correspondence table when said signal quality does not exceed a predetermined threshold.

8. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said direction detecting means is a dedicated device.

9. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said direction detecting means computes a direction of movement from a pair of points computed by said position computing means.

10. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said signal quality assessing means assesses said signal quality from a bit error rate.

15. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said direction detecting means is an earth magnetism sensor.

16. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said direction detecting means is a gyroscope.

17. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said signal quality assessing means assesses said signal quality from a receiving level.

18. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 7, wherein said signal quality assessing means assesses said signal quality from a C/N ratio.

11. An automatic beam switching apparatus in a multi-beam satellite communication system comprising:

position computing means for computing a current position of a mobile satellite communication terminal;

direction detection means for detecting a direction of movement of said mobile satellite communication terminal;

a position-beam correspondence table having a plurality of stored positions that correspond to a plurality of adjacent beams;

a direction-beam correspondence table having a plurality of stored angular directions that correspond to a plurality of adjacent beams;

a direction-beam correspondence table generating means for generating said direction-beam correspondence table;

a signal quality assessing means for assessing a signal quality of a signal received from said multi-beam satellite communication system; and

beam switching means for selecting a first beam by referencing said position-beam correspondence table, and for selecting a second beam by referencing said direction-beam correspondence table when said signal quality does not exceed a predetermined threshold.

12. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 11, wherein said direction detecting means is a dedicated device.

13. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 11, wherein said direction detecting means computes a direction of movement from a pair of points computed by said position computing means.

14. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 11, wherein said signal quality assessing means assesses said signal quality from a bit error rate.

19. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 11, wherein said direction detecting means is an earth magnetism sensor.

20. An automatic beam switching apparatus in a multi-beam satellite communication system according to claim 11, wherein said direction detecting means is a gyroscope.