SIGNALING METHOD IN AN OFDM MULTIPLE ACCESS SYSTEM

• US 20130016678A1
• Filed: 09/14/2012
• Published: 01/17/2013
• 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
• Granted Patent: US 9,426,012 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• 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 communication system for generating an OFDM signal having frequency tones distributed over a predetermined bandwidth, the communication system comprising:

an allocation circuit that defines an allocated tone set selected from frequency tones distributed over a predetermined bandwidth;

a mapping circuit that receives data symbols from a symbol constellation and maps the symbols to prescribed time instants in a time domain symbol duration to generate a discrete signal of mapped symbols;

an interpolation circuit that receives the discrete signal and generates a continuous signal by applying predetermined interpolation functions to the discrete signal, the interpolation functions operating on the discrete signal such that values of the continuous signal at the prescribed time instants are equal to the mapped symbols and a frequency response of the continuous signal includes sinusoids having non-zero values at frequency tones within the allocated tone set and zero values at the remaining frequency tones; and

a sampling circuit that samples the continuous signal at discrete time instants distributed over the time domain symbol duration to generate a digital signal sample vector.

2. A method for reducing a peak-to-average ratio in an OFDM communication signal transmitted by a communication device, the method comprising:

providing a time domain symbol duration having equally spaced time instants;

allocating a predetermined number of frequency tones to the communication device;

receiving as input data symbols to be transmitted by the OFDM communication signal;

mapping the data symbols to the equally spaced time instants in the symbol duration to generate a discrete signal of mapped symbols;

generating a continuous signal by applying an interpolation function to the discrete signal, the interpolation function operating on the discrete signal such that a frequency response of the continuous signal includes sinusoids having non-zero values at the allocated frequency tones, and zero values at frequency tones other than the allocated frequency tones; and

sampling the continuous signal at discrete time instants distributed over the time domain symbol duration, to generate a digital signal sample vector.

3. A method for reducing a peak-to-average ratio in an OFDM communication signal having a set of tones distributed over a predetermined bandwidth, the method comprising:

defining a symbol duration for the OFDM communication signal;

defining time instants in the symbol duration;

allocating frequency tones from the set of tones to a particular communication device;

receiving as input data symbols from a symbol constellation, the data symbols being transmitted by the OFDM communication signal;

mapping the data symbols to the time instants to generate a discrete signal in the time domain; and

generating a digital signal sample vector by applying interpolation functions to the discrete signal such that a frequency response of the digital signal sample vector includes sinusoids having non-zero values at allocated frequency tones, and zero values at frequency tones other than the allocated frequency tones.