Signaling method in an OFDM multiple access system

• US 8,098,569 B2
• Filed: 04/24/2009
• Issued: 01/17/2012
• Est. Priority Date: 09/13/2000
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Li, Junyi, Uppala, Sathyadev Venkata
• Primary Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US12/429,927
• Publication Number:
  US 20090296837A1
• Time in Patent Office: 998 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 digital processing system utilized in a transmitter that generates a transmission signal, the system comprising:

a first circuit that receives a discrete signal of complex data symbols, calculates a frequency response of the discrete signal, and outputs a first vector of length M;

a second circuit that receives the vector of length M and generates a second vector of length N, wherein the second vector of length N includes elements of the first vector at positions corresponding to tones allocated to the transmitter;

a third circuit that receives the second vector and generates a digital time domain vector therefrom for transmission by the transmitter by inserting zero value symbols corresponding to tones not allocated to the transmitter;

a fourth circuit configured to pre-pend a cyclic prefix to the digital time domain Vector; and

wherein the transmitter is configured to generate a signal representing the pre-pended digital time domain vector for transmission.

2. The digital processing system of claim 1, wherein the transmitter is configured to operate in a multiple access system, and wherein the tones allocated to the transmitter are a non-overlapping subset of frequency tones with respect to other transmitters.

3. The digital processing system of claim 1, wherein the vector of length N is larger than the vector of length M.

4. The digital processing system of claim 1, wherein the digital time domain vector comprises equally spaced tones.

5. The digital processing system of claim 3, wherein the digital time domain vector comprises equally spaced tones.

6. An apparatus that generates a transmission signal, the apparatus comprising:

means for receiving a discrete signal of complex data symbols, calculating a frequency response of the discrete signal, and outputting a first vector of length M;

means for receiving the vector of length M and generating a second vector of length N, wherein the second vector of length N includes elements of the first vector at positions corresponding to tones allocated to a transmitter;

means for generating a digital time domain vector of the second vector for transmission by the transmitter by inserting zero value symbols corresponding to tones not allocated to the transmitter;

means for pre-pending a cyclic prefix to the digital time domain vector; and

wherein the transmitter is configured to generate a signal representing the pre-pended digital time domain vector for transmission.

7. The apparatus of claim 6, wherein the transmitter is configured to operate in a multiple access system, and wherein the tones allocated to the transmitter are a nonoverlapping subset of frequency tones with respect to other transmitters.

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

9. The apparatus of claim 6, wherein the digital time domain vector comprises equally spaced tones.

10. The apparatus of claim 8, wherein the digital time domain vector comprises equally spaced tones.