Signaling method in an OFDM multiple access system

• US 7,916,624 B2
• Filed: 04/13/2010
• Issued: 03/29/2011
• Est. Priority Date: 09/13/2000
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Uppala, Sathyadev Venkata, Laroia, Rajiv, Li, Junyi
• Primary Examiner(s): Nguyen; Steven H
• Application Number:
  US12/759,634
• Publication Number:
  US 20100195487A1
• Time in Patent Office: 350 Days
• Field of Search: None
• US Class Current: 370/208
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26025 Numerology, i.e. varying one or more of symbol duration, subcarrier spacing, Fourier transform size, sampling rate or down-clocking allocating sub-channels of the transmission path H04L5/003
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601

Abstract

A method for reducing the peak-to-average ratio in an OFDM communication signal is provided. The method includes defining a constellation having a plurality of symbols, defining a symbol duration for the OFDM communication signal, and defining a plurality of time instants in the symbol duration. A plurality of tones are allocated to a particular communication device, and a discrete signal is constructed in the time domain by mapping symbols from the constellation to the time instants. A continuous signal is generated by applying an interpolation function to the discrete signal such that the continuous signal only includes sinusoids having frequencies which are equal to the allocated tones.

Claims

1. An apparatus for generating a vector of digital signal samples (S), the apparatus comprising:

a processor; and

a memory coupled to the processor, the memory including a set of instructions stored therein and executable by the processor to

receive a discrete signal of complex data symbols (C), calculate frequency responses (A₁, . . . A_M) corresponding to tones (f₍₁₎, . . . f_(M)), through an M-point discrete Fourier transform (DFT), and output a vector [A₁, . . . A_M] of length M,

expand the vector to a new vector of length N, and insert zero-value symbols corresponding to tones other than tones allocated to a transmitter,

perform an N-point inverse discrete Fourier transform (IDFT) operation on the new vector after zero insertion to obtain the vector of digital signal samples (S);

pre-pend a cyclic prefix to the vector of digital signal samples (S); and

generate a signal representing the pre-pended vector digital signal samples (S) for transmission.

2. The apparatus of claim 1, wherein the tones (f₍₁₎, . . . f_(M)) are allocated tones available for transmission.

3. The apparatus of claim 1, wherein the allocated tones are contiguous.

4. The apparatus of claim 1, wherein the vector of length N is larger than the vector of length M.

5. The apparatus of claim 1, wherein the allocated tones are equally spaced.

6. The apparatus of claim 2, wherein the allocated tones are contiguous.

7. The apparatus of claim 2, wherein the vector of length N is larger than the vector of length M.

8. The apparatus of claim 2, wherein the allocated tones are equally spaced.

9. The apparatus of claim 5, wherein the allocated tones are contiguous.

10. The apparatus of claim 5, wherein the vector of length N is larger than the vector of length M.

11. The apparatus of claim 9, wherein the vector of length N is larger than the vector of length M.

12. The apparatus of claim 6, wherein the vector of length N is larger than the vector of length M.

13. The apparatus of claim 12, wherein the allocated tones are equally spaced.

14. The apparatus of claim 7, wherein the allocated tones are equally spaced.

15. The apparatus of claim 7, wherein the allocated tones are contiguous.

16. The apparatus of claim 8, wherein the allocated tones are contiguous.

17. An apparatus for generating a vector of digital signal samples (S), the apparatus comprising:

a processor; and

at least one hardware module coupled to the processor and configured to

receive a discrete signal of complex data symbols (C), calculate frequency responses (A₁, . . . A_M) corresponding to tones (f₍₁₎, . . . f_(M)), through an M-point discrete Fourier transform (DFT), and output a vector [A₁, . . . A_M] of length M,

expand the vector [A₁, . . . A_M] to a new vector of length N, and insert zero-value symbols corresponding to tones other than tones allocated to a transmitter,

perform an N-point inverse discrete Fourier transform (IDFT) operation on the new vector after zero insertion to obtain the vector of digital signal samples (S),

pre-pend a cyclic prefix to the vector of digital signal samples (S); and

generate a signal representing the pre-pended vector of digital signal samples (S) for transmission.

18. The apparatus of claim 17, wherein the tones (f₍₁₎, . . . f_(M)) are allocated tones available for transmission.

19. The apparatus of claim 17, wherein the allocated tones are contiguous.

20. The apparatus of claim 17, wherein the vector of length N is larger than the vector of length M.

21. The apparatus of claim 17, wherein the allocated tones are equally spaced.

22. The apparatus of claim 18, wherein the allocated tones are contiguous.

23. The apparatus of claim 18, wherein the vector of length N is larger than the vector of length M.

24. The apparatus of claim 18, wherein the allocated tones are equally spaced.

25. The apparatus of claim 21, wherein the allocated tones are contiguous.

26. The apparatus of claim 21, wherein the vector of length N is larger than the vector of length M.

27. The apparatus of claim 25, wherein the vector of length N is larger than the vector of length M.

28. The apparatus of claim 22, wherein the vector of length N is larger than the vector of length M.

29. The apparatus of claim 28, wherein the allocated tones are equally spaced.

30. The apparatus of claim 23, wherein the allocated tones are equally spaced.

31. The apparatus of claim 23, wherein the allocated tones are contiguous.

32. The apparatus of claim 24, wherein the allocated tones are contiguous.