Signaling method in an OFDM multiple access system

• US 8,014,271 B2
• Filed: 07/10/2008
• Issued: 09/06/2011
• 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 D
• Application Number:
  US12/171,155
• Publication Number:
  US 20090010351A1
• Time in Patent Office: 1,153 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. A processor-based apparatus for generating wireless communications, the apparatus comprising:

a first circuit configured to perform a Discrete Fourier Transform (DFT) on a discrete signal of complex data symbols to obtain a first frequency response vector of length M;

a second circuit configured to expand the first frequency response vector to obtain a second frequency response vector of length N;

a third circuit configured to perform an N-point Inverse DFT (IDFT) on the second frequency response vector to obtain a vector of digital signal samples by inserting zero-value symbols corresponding to tones other than tones allocated to a transmitter;

a fourth circuit configured to pre-pend a cyclic prefix to the vector of digital signal samples; and

a fifth circuit configured to generate a signal representing the pre-pended vector of digital signal samples for transmission.

2. The apparatus of claim 1, wherein the second frequency response vector has entries corresponding to tones other than tones allocated to the apparatus.

3. The apparatus of claim 2, wherein the first circuit performs a DFT with a set of tones allocated to the apparatus for transmission.

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

5. The apparatus of claim 3, wherein the allocated tones are equally spaced.

6. The apparatus of claim 1, wherein the first, second, third, and fourth circuits comprise a combination of hardware and software modules.

7. The apparatus of claim 1, wherein at least one of the first, second, third, and fourth circuits comprises a software module.

8. The apparatus of claim 1, wherein the fifth circuit comprises:

a circuit configured to convert the pre-pended vector of digital signal samples to an analog signal.

9. The apparatus of claim 8, wherein the fifth circuit further comprises:

a circuit configured to modulate the analog signal to a carrier frequency for transmission.

10. The apparatus of claim 9, wherein the fifth circuit further comprises:

a pulse filter circuit configured to process the analog signal prior to modulation to the carrier frequency.

11. The apparatus of claim 9, further comprising:

at least one antenna; and

a power amplifier circuit configured to amplify the analog signal prior to transmission via the at least one antenna.

12. A method for wireless communications utilizing at least one processor, comprising:

performing a Discrete Fourier Transform (DFT) on a discrete signal of complex data symbols to obtain a first frequency response vector of length M;

expanding the first frequency response vector to obtain a second frequency response vector of length N by inserting zero-value symbols corresponding to tones other than tones allocated to a transmitter;

performing an N-point Inverse DFT (IDFT) on the second frequency response vector to obtain a vector of digital signal samples;

pre-pending a cyclic prefix to the vector of digital signal samples; and

generating a signal representing the pre-pended vector of digital signal samples for transmission.

13. The method of claim 12, wherein the second frequency response vector has entries corresponding to tones other than tones allocated to the apparatus.

14. The method of claim 13, wherein the DFT is performed with a set of tones allocated to the apparatus for transmission.

15. The method of claim 14, wherein the allocated tones are contiguous.

16. The method of claim 14, wherein the allocated tones are equally spaced.

17. The method of claim 12, wherein the performing a DFT, expanding the first frequency response vector, performing an N-point IDFT, and pre-pending a cyclic prefix are performed by a combination of hardware and software modules.

18. The method of claim 12, wherein at least one of the performing a DFT, expanding the first frequency response vector, performing an N-point IDFT, and pre-pending a cyclic prefix is performed by a software module.

19. The method of claim 12, wherein generating the signal representing the pre-pended vector of digital signal samples for transmission comprises:

converting the pre-pended vector of digital signal samples to an analog signal.

20. The method of claim 19, wherein generating the signal representing the pre-pended vector of digital signal samples for transmission further comprises:

modulating the analog signal to a carrier frequency for transmission.

21. The method of claim 20, wherein generating the signal representing the pre-pended vector of digital signal samples for transmission further comprises:

performing pulse filtering of the analog signal prior to modulation to the carrier frequency.

22. The method of claim 20, further comprising:

amplifying the analog signal prior to transmission via at least one antenna.

23. A processor-based apparatus for generating wireless communications, the apparatus comprising:

means for performing a Discrete Fourier Transform (DFT) on a discrete signal of complex data symbols to obtain a first frequency response vector of length M;

means for expanding the first frequency response vector to obtain a second frequency response vector of length N by inserting zero-value symbols corresponding to tones other than tones allocated to a transmitter;

means for performing an N-point Inverse DFT (IDFT) on the second frequency response vector to obtain a vector of digital signal samples;

means for pre-pending a cyclic prefix to the vector of digital signal samples; and

means for generating a signal representing the pre-pended vector of digital signal samples for transmission.

24. The apparatus of claim 23, wherein the second frequency response vector has entries corresponding to tones other than tones allocated to the apparatus.

25. The apparatus of claim 24, wherein the means for performing a DFT performs a DFT with a set of tones allocated to the apparatus for transmission.

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

27. The apparatus of claim 25, wherein the allocated tones are equally spaced.

28. The apparatus of claim 23, wherein the means for performing a DFT, means for expanding the first frequency response vector, means for performing an N-point IDFT, and means for pre-pending a cyclic prefix comprise a combination of hardware and software modules.

29. The apparatus of claim 23, wherein at least one of the means for performing a DFT, means for expanding the first frequency response vector, means for performing an N-point IDFT, and means for pre-pending a cyclic prefix comprises a software module.

30. The apparatus of claim 23, wherein the means for generating comprises:

means for converting the pre-pended vector of digital signal samples to an analog signal.

31. The apparatus of claim 30, wherein the means for generating further comprises:

means for modulating the analog signal to a carrier frequency for transmission.

32. The apparatus of claim 31, wherein the means for generating further comprises:

means for performing pulse filtering of the analog signal prior to modulation to the carrier frequency.

33. The apparatus of claim 31, further comprising:

at least one antenna; and

means for amplifying the analog signal prior to transmission via the at least one antenna.