Method and system for multirate multiuser modulation

• US 7,701,839 B2
• Filed: 11/20/2006
• Issued: 04/20/2010
• Est. Priority Date: 12/29/2000
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Nangia, Vijay, Ramasubramanian, Karthik, Baum, Kevin Lynn
• Primary Examiner(s): Pham; Chi H
• Assistant Examiner(s): Elallam; Ahmed
• Application Number:
  US11/561,481
• Publication Number:
  US 20070091866A1
• Time in Patent Office: 1,247 Days
• Field of Search: 370/203, 370/204, 370/208, 370/210, 370/344, 370/480, 370/328, 370/329, 375/239, 375/260, 455/17, 455/45, 455 59- 61, 455/450, 455/451, 455/451.1
• US Class Current: 370/208
• CPC Class Codes: H04B 2201/70703 using multiple or variable rates
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/18 Allocation of orthogonal codes
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

A multi-rate interleaved frequency division multiple access (IFDMA) modulation scheme permits users to transmit at different data rates or to vary their data rates while providing frequency diversity and preserving low peak-to-average power ratios and orthogonality between user data rates. The modulation scheme allows user-specific data block and repetition sizes, as well as user-specific modulation codes. Code assignment rules are provided for maintaining orthogonality between the different user data rates. Block and phase ramp modulation codes can be used. Asynchronous transmissions by users are supported by ensuring that the length of the cyclic extension is sufficiently long to tolerate worst case relative signal arrival delays between users and the channel pulse response duration over the communication medium. The modulation scheme can be employed in wireless communication systems, such as cellular or paging systems.

Claims

1. Method for performing orthogonal multiple access, the method comprising the steps of:

a first subscriber unit within a communication system being assigned a first set of subcarriers comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform, and wherein the first set of subcarriers are used for transmitting a first single-carrier symbol stream;

a second subscriber unit within the communication system being assigned a second set of subcarriers comprising a second number of subcarriers, wherein spacing between neighboring subcarriers within the second set of subcarriers is uniform and wherein the second set of subcarriers are used for transmitting a second single-carrier symbol stream;

wherein the first number of subcarriers differs from the second number of subcarriers;

wherein the first and the second set of subcarriers are assigned in an orthogonal fashion; and

wherein the first and the second set of subcarriers are used for frequency division multiple access between the first and the second subscriber units.

2. The method of claim 1 wherein the first set of subcarriers are used for transmitting a signal with nulls in frequency positions of the second set of subcarriers.

3. The method of claim 1 wherein the first set of subcarriers exist between the second set of subcarriers.

4. The method of claim 1 wherein the step of being assigned the first and the second set of subcarriers comprises the step of being assigned a first and a second symbol-block repetition value.

5. The method of claim 1 wherein the step of being assigned the first and the second set of subcarriers comprises the step of being assigned a first and a second symbol-block size.

6. The method of claim 1 wherein the step of being assigned the first and the second set of subcarriers comprises the step of being assigned a first and a second channelization code from a set of mutually orthogonal channelization codes.

7. The method of claim 1 wherein the step of being assigned the first and the second set of subcarriers comprises the step of being assigned a first and a second modulation code from a set of mutually orthogonal modulation codes.

8. The method of claim 1 wherein the step of being assigned the first and the second set of subcarriers comprises the step of being assigned a particular first and a second subcarrier and a first and a second spacing between the a first and a second set of subcarriers.

9. The method of claim 1 wherein the spacing between neighboring subcarriers within the second set of subcarriers comprises one subcarrier.

10. The method of claim 1 wherein the spacing between neighboring subcarriers within the second set of subcarriers comprises two or more subcarriers.

11. The method of claim 1, wherein the first set of subcarriers are used by the first subscriber unit for transmitting the single-carrier symbol stream resulting in a first transmitted signal having a single-carrier peak-to-average characteristic.

12. A method comprising the steps of:

a subscriber unit within a communication system receiving a subcarrier assignment;

the subscriber unit generating a signal to be transmitted, wherein the signal comprises a first set of subcarriers corresponding to the received subcarrier assignment comprising a first number of subcarriers, wherein spacing between neighboring subcarriers within the first set of subcarriers is uniform, and wherein the first set of subcarriers are used for transmitting a single-carrier symbol stream;

wherein the first number of subcarriers differs from a second number of subcarriers assigned to a second subscriber unit;

wherein the first and the second set of subcarriers are assigned in an orthogonal fashion;

wherein the first set of subcarriers are to be used for frequency division multiple access; and

the subscriber unit transmitting the frequency division multiplexed signal.

13. The method of claim 12 wherein the signal comprises a user-specific symbol-block repetitions of a basic symbol-block when viewed in the time domain.

14. The method of claim 12 wherein the first set of subcarriers are used for transmitting a signal with nulls in frequency positions of the second set of subcarriers.

15. The method of claim 12 wherein the first set of subcarriers exist between the second set of subcarriers.

16. The method of claim 12 wherein the step of receiving a subcarrier assignment comprises the step of receiving a symbol-block repetition value.

17. The method of claim 12 wherein the step of receiving a subcarrier assignment comprises the step of receiving a symbol-block size.

18. The method of claim 12 wherein the step of receiving a subcarrier assignment comprises the step of receiving an orthogonal channelization code.

19. The method of claim 12 wherein the step of receiving a subcarrier assignment comprises the step of receiving one of a set of mutually orthogonal modulation codes.

20. The method of claim 12 wherein the step of receiving a subcarrier assignment comprises the step of receiving a subcarrier and a spacing between the assigned subcarriers.

21. The method of claim 12 wherein the spacing between neighboring subcarriers within the first set of subcarriers comprises one subcarrier.

22. The method of claim 12 wherein the spacing between neighboring subcarriers within the first set of subcarriers comprises two or more subcarriers.