Burst output timing control system in satellite communication system

• US 5,613,195 A
• Filed: 02/23/1996
• Issued: 03/18/1997
• Est. Priority Date: 05/12/1993
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Ooi, Tomoyuki
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): TO, DORIS HA
• Application Number:
  US08/606,227
• Time in Patent Office: 389 Days
• Field of Search: 455/12.1, 455/13.2, 455/51.1, 455/51.2, 455/13.1, 455/33.1, 455/53.1, 455/56.1, 455/67.1, 455/67.6, 455/67.5, 455/88, 370/104.1, 370/100.1, 375/356, 375/354
• US Class Current: 455/13.2
• CPC Class Codes: H04B 7/2125 Synchronisation

Abstract

In a method for controlling a burst output timing in a satellite communication system for performing radio communication between a central earth station and a plurality of remote earth stations via a satellite, the time between a transmission of burst data from each of the remote earth stations to the central earth station via the satellite and the reception of the burst data returned from the central earth station via the satellite is time-counted. The output timing of the burst data transmitted from each remote earth station is adjusted, when the burst data is to be sent to the central earth station, in accordance with a time difference between the time and a preset reference time. A burst output timing control system is also disclosed.

Claims

1. A method for controlling a burst output timing in a satellite communication system for performing radio communication between a central earth station and a plurality of remote earth stations via a satellite, comprising the steps of;

time-counting a time between a transmission of burst data from each of said remote earth stations to a central earth station via the satellite and a reception of the burst data returned from the central earth station via the satellite; and

adjusting an output timing of the burst data transmitted from each remote earth station, when the burst data is to be sent to said central earth station, in accordance with a time difference between said time counting time and a preset reference time which is a time between a transmission of burst data from a reference remote earth station to the central earth station via the satellite and a reception of the burst data returned from the central earth station via the satellite.

2. A burst output timing control system in a satellite communication system for performing radio communication between a central earth station and a plurality of remote earth stations via a satellite, each of said remote earth stations comprising:

burst generating means for generating burst data;

timer means for starting a time counting operation at the same time when said burst generating means generates the burst data,

burst output timing adjusting means for outputting the burst data, generated by said burst generating means, at a predetermined output timing so as to allow adjustment of the output timing;

transmission means for transmitting the burst data output from said burst timing adjusting means; and

reception means for receiving the burst data which is transmitted from said transmission means and reaches said central earth station via said satellite, and is returned to said remote earth station via said satellite from said central earth station,

wherein said remote earth station stops the time counting operation of said timer means upon reception of the burst data transmitted from said remote earth station, compares the counted time (Ta) between generation of the burst data and reception of the burst data with a preset reference time (Tb), and controls said burst output timing adjusting means on the basis of a difference between the counted time and the preset reference time, thereby adjusting an output timing of the burst data.

3. A burst output timing control system in a satellite communication system according to claim 2, wherein said preset reference time (Tb) is defined based on a distance among the earth station, the satellite and the central earth station, the earth station being the remotest from the central station.

4. A burst output timing control system in a satellite communication system according to claim 2, wherein said preset reference time (Tb) is defined based on a propagation time of the burst data among the earth station, satellite and the central earth station, the earth station being the remotest from the central station.

5. A burst output timing control system in a satellite communication system according to claim 2, wherein said burst output timing adjusting means comprises means for advancing the output timing of said burst data 1/2 the difference time between said Ta and said Tb when Ta>

Tb and delaying the output timing of said burst data by 1/2 the difference time between said Ta and said Tb when Ta<

Tb.

6. A burst output timing control system in a satellite communication system according to claim 2, wherein said burst data comprises an ID code assigned to each of said remote earth stations for identifying each of them.

7. A burst output timing control system in a satellite communication system for performing radio communication between a central earth station and a plurality of remote earth stations via a satellite, each of said remote earth stations comprising;

burst generation circuit for generating burst data;

timer circuit for starting a time counting operation at the same time when said burst generation circuit generates the burst data,

burst timing adjusting circuit for outputting the burst data, generated by said burst generating circuit, at a predetermined output timing so as to allow adjustment of the output timing;

RF unit for transmitting the burst data output from said burst timing adjusting circuit and for receiving the burst data which is transmitted therefrom, which reaches said central earth station via said satellite, and which is returned to said remote earth station via said satellite from said central earth station,

wherein said remote earth station stops the time counting operation of said timer circuit upon reception of the burst data transmitted from said remote earth station, compares the counted time (Ta) between generation of the burst data and reception of the burst data with a preset reference time (Tb), and controls said burst timing adjusting circuit on the basis of a difference between the counted time and the preset reference time, thereby adjusting an output timing of the burst data.

8. A burst output timing control system in a satellite communication system according to claim 7, wherein said preset references time (Tb) is defined based on a distance among the earth station, the satellite and the central earth station, the earth station being the remotest from the central station.

9. A burst output timing control system in a satellite communication system according to claim 7, wherein said preset reference time (Tb) is defined based on a propagation time of the burst data among the earth station, the satellite and the central earth station, the earth station being the remotest from the central station.

10. A burst output timing control system in a satellite communication system according to claim 7, wherein said burst timing adjusting circuit comprises means for advancing the output timing of said burst date 1/2 the difference time between said Ta and Tb when Ta>

Tb, and for delaying the output timing of said burst data by 1/2 the difference time between said Ta and said Tb when Ta<

Tb.

11. A burst output timing control system in a satellite communication system according to claim 7, wherein said burst data comprises an ID code assigned to each of said remote earth stations for identifying each of them.