Reverse link for a satellite communication network

• US 6,240,073 B1
• Filed: 11/14/1997
• Issued: 05/29/2001
• Est. Priority Date: 11/14/1997
• Status: Expired due to Term

• Current Assignee: Elbit Systems Land and C4I - Tadiran Limited (Elbit Systems Limited)
• Original Assignee: Shiron Satellite Communications Limited
• Inventors: Reichman, Arie, Laufer, Shaul, Barda, Avi, Goldenberg, Sorin
• Primary Examiner(s): VU, HUY DUY
• Application Number:
  US08/970,922
• Time in Patent Office: 1,292 Days
• Field of Search: 370/352, 370/353, 370/354, 370/355, 370/356, 370/335, 370/342, 370/368, 370/365, 370/465, 370/319, 370/431, 370/433, 370/437, 370/320, 370/321, 370/343, 370/478, 370/436, 375/202, 375/205, 375/201
• US Class Current: 370/319
• CPC Class Codes: H04B 7/1858 Arrangements for data transmission on the physical system, i.e. for data bit transmission between network components

Abstract

The present invention is a return link for a satellite communication system. The return link described herein is suitable for use in any type of communications network such as networks used for Internet access purposes. The return link in combination with a forward link forms a complete two way communication system via satellite. The return link comprises two separate communication schemes used in combination to implement the return link of the satellite system. The first communication scheme uses a random access method based on a non synchronous frequency hopping code division multiple access technique (NS/FH/CDMA). The second communication scheme uses a channel assignment method based on a frequency division multiple access (FDMA) technique. Data generated by a user is transmitted utilizing one of the two communication schemes in accordance with the content and amount of data generated. Messages requiring a relatively low transmission rate, such as short bursty messages, utilize the random access transmission method. On the other hand, messages requiring a higher transmission rate, such as video conferencing, utilize the channel assignment method.

Claims

1. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said receiver means comprises;

means for receiving data transmitted by said plurality of user terminals using said first communication means, said first communication means utilizing non synchronous frequency hopping code division multiple access communications;

means for receiving data transmitted by said plurality of user terminals using said second communication means, said second communication means utilizing frequency division multiple access communications; and

means for receiving preamble and synchronization message data transmitted by said plurality of user terminals precedent to transmissions utilizing said first communication means.

20. The system according to claim 1, further comprising interface means for interfacing said at least one hub to an external communications network.

21. The system according to claim 20, wherein said external communications network comprises the Internet.

22. The system according to claim 20, wherein said external communications network comprises a packet switched telephone network (PSTN).

23. The system according to claim 20, wherein said external communications network comprises an Integrated Services Digital Network (ISDN).

24. The system according to claim 20, wherein said external communications network comprises a Community Antenna Television (CATV) network.

25. The system according to claim 20, wherein said external communications network comprises a Digital Subscriber Loop (xDSL).

26. The system according to claim 20, wherein said external communications network comprises a Frame Relay network.

35. The system according to claim 20, wherein said external communications network comprises a Digital Subscriber Loop (xDSL).

36. The system according to claim 20, wherein said external communications network comprises a Frame Relay network.

2. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching from said first communication means to said second communication means when the length of a message received by said transmitter means exceeds a predetermined threshold.

3. A access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching transmission from said first communication means to said second communication means when a continuation flag in a message received by said transmitter means is turned on.

4. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching transmission from said first communication means to said second communication means when a user buffer containing a plurality of messages to be sent via said transmitter means fills beyond predetermined level.

5. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching transmission from said second communication means to said first communication means when the length of a message received by said transmitter means fails to exceed a predetermined threshold.

6. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching transmission from said second communication means to said first communication means when a continuation flag in a message received by said transmitter means is turned off.

7. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

wherein said switching means comprises means for switching transmission from said second communication means to said first communication means when the software application meeting a predetermined criteria that initiated a message to be transmitted via said transmitter means ceases to generate message data.

8. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for generating data to be transmitted over said multiple access communication system;

at least one hub for receiving data over said multiple access communication system from said plurality of user terminals;

transmitter means within each user terminal for receiving data to be transmitted from said user terminal to said hub, said transmitter means including first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means coupled to said transmitter means for switching transmission between said first communication means and said second communication means in accordance with predefined criteria, and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means;

p1 wherein said at least one hub comprises collision detection means for determining when two frequency hops associated with two independent receivers are utilizing the same frequency at the same time, thus improving decoding within said receiver means.

9. A multiple access communication system for use in a satellite communication network, said satellite communication network including a plurality of user terminals and at least one hub, said system comprising:

first transmitter means for transmitting data utilizing a non synchronous frequency hopping code division multiple access communication scheme;

second transmitter means for transmitting data utilizing a frequency division multiple access communication scheme;

switching means for switching transmission between said first transmitter means and said second transmitter means in accordance with predefined criteria;

first receiver means for receiving data transmitted using utilizing said non synchronous frequency hopping code division multiple access communication scheme;

second receiver means for receiving data transmitted using said frequency division multiple access communication scheme; and

third receiver means for receiving preamble and synchronization data transmitted utilizing said utilizing a non synchronous frequency hopping code division multiple access communication scheme.

10. The system according to claim 9, wherein said switching means comprises means for switching transmission from said first transmitter means to said second transmitter means in accordance with a source port field within messages received by said transmitter means.

11. The system according to claim 9, wherein said switching means comprises means for switching transmission from said first transmitter means to said second transmitter means when the length of a message received by said transmitter means exceeds a predetermined threshold.

12. The system according to claim 9, wherein said switching means comprises means for switching transmission from said first transmitter means to said second transmitter means when a continuation flag in a message received by said transmitter means is turned on.

13. The system according to claim 9, wherein said switching means comprises means for switching transmission from said first transmitter means to said second transmitter means when a user buffer containing a plurality of messages to be sent via said transmitter means fills beyond predetermined level.

14. The system according to claim 9, wherein said switching means comprises means for switching transmission from said first transmitter means to said second transmitter means in accordance with the type and nature of the software application that initiated a message to be transmitted via said transmitter means.

15. The system according to claim 9, wherein said switching means comprises means for switching transmission from said second transmitter means to said first transmitter means when a source port matching a predetermined criteria ceases to transmit messages.

16. The system according to claim 9, wherein said switching means comprises means for switching transmission from said second transmitter means to said first transmitter means when the length of a message received by said transmitter means fails to exceed a predetermined threshold.

17. The system according to claim 9, wherein said switching means comprises means for switching transmission from said second transmitter means to said first transmitter means when a continuation flag in a message received by said transmitter means is turned off.

18. The system according to claim 9, wherein said switching means comprises means for switching transmission from said second transmitter means to said first transmitter means when a user buffer containing a plurality of messages to be sent via said transmitter means empties.

19. The system according to claim 9, wherein said switching means comprises means for switching transmission from said second transmitter means to said first transmitter means when the software application meeting a predetermined criteria that initiated a message to be transmitted via said transmitter means ceases to generate message data.

27. The system according to claim 9, further comprising collision detection means for determining when two frequency hops associated with two independent receivers within said receiver means are utilizing the same frequency at the same time, thus improving decoding within said first receiver means.

30. The system according to claim 9, further comprising interface means for interfacing said at least one hub to an external communications network.

31. The system according to claim 30, wherein said external communications network comprises the Internet.

32. The system according to claim 30, wherein said external communications network comprises a packet switched telephone network (PSTN).

33. The system according to claim 30, wherein said external communications network comprises an Integrated Services Digital Network (ISDN).

34. The system according to claim 30, wherein said external communications network comprises a Community Antenna Television (CATV) network.

28. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for transmitting and receiving data over said multiple access communication system;

at least one hub for transmitting and receiving data over said multiple access communication system to and from said plurality of user terminals;

a forward communication link for transmitting data from said at least one hub to said plurality of user terminals;

a return communication link for transmitting data from said plurality of user terminals to said at least one hub, said return communication link including a first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means within said plurality of user terminals for switching transmission between said first communication means and said second communication means in accordance with predefined criteria; and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means,

wherein each user terminal comprises means for generating a request to be sent over said return communications link in order to utilize said second communication means.

29. A multiple access communications system for use in a satellite communication network, comprising:

a plurality of user terminals for transmitting and receiving data over said multiple access communication system;

at least one hub for transmitting and receiving data over said multiple access communication system to and from said plurality of user terminals;

a forward communication link for transmitting data from said at least one hub to said plurality of user terminals;

a return communication link for transmitting data from said plurality of user terminals to said at least one hub, said return communication link including a first communication means for transmitting short bursty data in combination with second communication means for continuous transmission of data;

switching means within said plurality of user terminals for switching transmission between said first communication means and said second communication means in accordance with predefined criteria; and

receiver means within said at least one hub adapted to receive data transmitted by said plurality of terminals utilizing either said first communication means or said second communication means,

wherein said at least one hub comprises means for polling each user terminal over said forward communication link as to whether said transmission of data should be switched to utilize said second communication means.