CODE DIVISION MULTIPLE ACCESS BASED CONTINGENCY TRANSMISSION

• US 20100124164A1
• Filed: 11/19/2008
• Published: 05/20/2010
• Est. Priority Date: 11/19/2008
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Martin, G. Patrick, Adams, William C. JR.
• Granted Patent: US 8,169,886 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0678 using different spreading codes between antennas code allocation H04J13/16
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme

Abstract

Systems (100) and methods (500) for method for providing a redundant or distinct transmission feature to a communication system (100). The methods involve (508) detecting if there is a communication system fault. If a communication system fault is detected (508:YES), then (512) a plurality of modified transmit signals are generated by combining a transmit signal with a plurality of complex weights (W₁, W₂, W₃). The modified transmit signals are then (514) transmitted from a plurality of antenna elements (106a, 106b, 106c) of the communication system to an object of interest (108). If a communication systems fault is detected (508:NO), then (526) a plurality of redundant or distinct transmit signals are generated by combining the transmit signal with a plurality of first orthogonal or approximately orthogonal numerical sequences. The redundant or distinct transmit signals can then be (528) synchronously transmitted from the antenna elements.

Claims

1. A method for providing a redundant or distinct transmission feature to a communication system, comprising:

detecting at the communication system if there is a communication systems fault;

if the communication systems fault is not detected, generating a plurality of modified transmit signals by combining a transmit signal with a plurality of complex weights and transmitting the plurality of modified transmit signals from a plurality of antenna elements of the communication system to an object of interest; and

if the communication systems fault is detected, generating a plurality of redundant or distinct transmit signals by combining the transmit signal with a plurality of first orthogonal or approximately orthogonal numerical sequences and synchronously transmitting the plurality of redundant or distinct transmit signals from the plurality of antenna elements of the communication system.

2. The method according to claim 1, further comprising generating the plurality of first orthogonal numerical sequences using a plurality of orthogonal Walsh Functions.

3. The method according to claim 1, wherein the plurality of first approximately orthogonal numerical sequences are random or pseudo-random number sequences.

4. The method according to claim 1, wherein the plurality of first approximately orthogonal numerical sequences are chaotic sequences.

5. The method according to claim 1, wherein the communication system fault is a result of an operational failure occurring at the communication system.

6. The method according to claim 5, wherein the operational failure is associated with a navigation system.

7. The method according to claim 1, wherein the communication system fault is a result of an operational failure occurring at the object of interest.

8. The method according to claim 1, further comprising receiving the plurality of modified transmit signals at the object of interest and processing the plurality of modified transmit signals to recover information contained therein.

9. The method according to claim 1, further comprising receiving the plurality of redundant or distinct transmit signals at the object of interest and processing the plurality of redundant or distinct transmit signals to recover information contained therein.

10. The method according to claim 9, further comprising generating a plurality of second orthogonal or approximately orthogonal numerical sequences at the object of interest and using the plurality of second orthogonal or approximately orthogonal numerical sequences to despread the plurality of redundant or distinct transmit signals, wherein the plurality of second orthogonal or approximately orthogonal numerical sequences are the same as the plurality of first orthogonal or approximately orthogonal numerical sequences.

11. The method according to claim 1, further comprising placing the communication systems in redundant data modes in which low spreading ratios and high data rates are employed or in distinct data modes in which high spreading ratios and low data rates are employed.

12. A communication system, comprising:

a detection device for detecting if there is a communication system fault;

a plurality of beamformers for generating a plurality of modified transmit signals by combining a transmit signal with a plurality of complex weights if the communication system fault is not detected; and

a plurality of combiners for generating a plurality of redundant or distinct transmit signals by combining the transmit signal with a plurality of first orthogonal or approximately orthogonal numerical sequences if the communication system fault is detected; and

a plurality of antenna elements for transmitting the plurality of modified transmit signals to an object of interest and synchronously transmitting the plurality of redundant or distinct transmit signals therefrom.

13. The communication system according to claim 12, further comprising at least one orthogonal sequence generator for generating the plurality of first orthogonal numerical sequences using a plurality of orthogonal Walsh Functions.

14. The communication system according to claim 12, wherein the plurality of first orthogonal or approximately orthogonal numerical sequences are random number sequences, pseudo-random number sequences, or chaotic sequences.

15. The communication system according to claim 12, wherein the communication system fault is a result of an operational failure occurring at the communication system.

16. The communication system according to claim 15, wherein the operational failure is associated with a navigation system.

17. The communication system according to claim 12, wherein the communication system fault is a result of an operational failure occurring at the object of interest.

18. The communication system according to claim 12, wherein the object of interest is configured for receiving the plurality of modified transmit signals and processing the plurality of modified transmit signals to recover information contained therein.

19. The communication system according to claim 12, wherein the object of interest is configured for receiving the plurality of redundant or distinct transmit signals and processing the plurality of redundant or distinct transmit signals to recover information contained therein.

20. The communication system according to claim 19, wherein the object of interest is further configured for generating a plurality of second orthogonal or approximately orthogonal numerical sequences and using the plurality of second orthogonal or approximately orthogonal numerical sequences to despread the plurality of redundant or distinct transmit signals, wherein the plurality of second orthogonal or approximately orthogonal numerical sequences are the same as the plurality of first orthogonal or approximately orthogonal numerical sequences.