Signal spectrum spreading and combining system and method

• US 7,545,849 B1
• Filed: 03/28/2003
• Issued: 06/09/2009
• Est. Priority Date: 03/28/2003
• Status: Expired due to Fees

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Gunter, Michial Allen
• Primary Examiner(s): Fan; Chieh M
• Assistant Examiner(s): Perilla; Jason M.
• Application Number:
  US10/402,878
• Time in Patent Office: 2,265 Days
• Field of Search: 375130-153, 375/343, 375/316, 375/295
• US Class Current: 375/146
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/102 Combining codes
• CPC Class Codes: H04L 5/22 using time-division multiplexing

Abstract

The present invention facilitates efficient and effective combination of multiple spread spectrum signals into a single stream. A spread spectrum signal combination system and method of the present invention facilitates fast communication of information and increases overall network communication performance by coordinating conversion from spread spectrum protocols to single stream communication protocols. A plurality of signals can be combined into a single stream of information by selecting among them on a chip time basis in a predetermined pattern (a pseudo-random pattern). The predetermined pattern can be balanced and have the same number of ones and zeroes (e.g., a balanced pattern stored in a precomputed table with randomly arranged rows). For example, the predetermined pattern can be implemented with a shuffled Hadamard function. Alternatively, the selection part of a Hadamard table can be replaced with a pseudo-random number generator such that the rest of the table remains as a shuffled Hadamard.

Claims

1. A signal combination method comprising:

Combining, with a multiplexer, a plurality of independent, unrelated spread spectrum signals into a single stream of information by selecting among them on a chip time basis in a predetermined pattern, wherein said predetermined pattern is implemented with a shuffled Walsh/Hadamard function with pseudo-randomly scrambled rows; and

forwarding said single stream of information.

2. A signal combination method of claim 1 wherein the plurality of independent unrelated spread spectrum signals are direct-sequence spread spectrum signals.

3. A signal combination method of claim 1 wherein said predetermined pattern is balanced by having the same number of ones and zeros.

4. A signal combination method of claim 1 wherein said predetermined pattern is pseudo-random.

5. A signal combination method of claim 4 further comprising implementing said pseudo-random pattern using a pseudo-random generator.

6. A signal combination method of claim 4 wherein said pseudo-random pattern is balanced by including the same number of ones and zeros.

7. A signal combination method of claim 1, wherein said predetermined pattern is stored in a pre-computed table.

8. A signal combination method of claim 7 wherein said table is produced using random numbers.

9. A signal combination method of claim 7 wherein said table is balanced.

10. A signal combination method of claim 7 wherein said predetermined pattern is implemented with all or a subset of a shuffled Hadamard matrix.

11. A signal combination system comprising:

a plurality of input lines configured to communicate multiple independent, unrelated streams of time-varying information;

a multiplexer coupled to said plurality of input lines, said multiplexer multiplexing said multiple independent, unrelated streams of time-varying information into a single stream of information;

a chip time basis control component coupled to said multiplexer, said chip time basis control component controlling said multiplexing on a chip time basis, wherein said chip time basis control component further comprises a lookup table; and

a counter coupled to said lookup table, said counter pointing to the row which is to be used in said lookup table, and wherein said lookup table comprises a pre-generated matrix corresponding to a Walsh/Hadamard function with pseudo-randomly scrambled rows; and

a single output line coupled to said multiplexer, said single output line for communicating said single stream of information.

12. A signal combination system of claim 11 wherein said chip time basis control component provides multiplexing selection bits corresponding to communication modulation codes of a communication system.

13. A signal combination system of claim 12 wherein said selection bits correspond to a spread spectrum signal protocol.

14. A signal combination system of claim 12 wherein said selection bits correspond to all or a subset of a shuffled Hadamard matrix.

15. A signal combination system of claim 11 wherein said lookup table comprises rows of orthogonal random bit sequences.

16. A signal combination system of claim 11 wherein said lookup table comprises rows which are randomly shuffled by scrambling the order of said rows in accordance with a randomly generated number.

17. A signal combination system of claim 11 wherein said lookup table is stored in a memory coupled to the select bits of a multiplexer.

18. A signal combination system of claim 11 wherein said lookup table is a shuffled Hadamard matrix.

19. A single combination system of claim 18 wherein the multiplexer is controlled using a subset of the columns of said shuffled Hadamard matrix.

20. A signal combination system of claim 19 wherein all or a subset of columns is generated using a pseudo-random number generator.

21. A signal combination system comprising:

a means for conveying a plurality of independent, unrelated spread spectrum signals;

a means for selecting between said plurality of independent, unrelated spread spectrum signals;

a means for directing said selection on a chip time basis, wherein said chip time basis corresponds to a shuffled Walsh/Hadamard function; and

a means for forwarding said selected spread spectrum signals.

22. A signal combination system of claim 21 further comprising a means for establishing said chip time basis.

23. A signal combination system of claim 22 wherein said means for establishing said chip time basis comprises a means for looking up a selection sequence.

24. A signal combination system of claim 22 wherein said means for establishing said chip time basis comprises a means for generating a selection sequence.