Signaling method in an OFDM multiple access system
AssigneeQUALCOMM Incorporated
InventorsRajiv Laroia, Junyi Li, Sathyadev Venkata Uppala
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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.
Claims73
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.
A communication system for generating an OFDM signal having allocated frequency tones distributed over a predetermined bandwidth, the communication system comprising:
- a mapping module 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;
- and
- an interpolation module that receives the discrete signal and generates a continuous signal by applying an interpolation function to the discrete signal;
- wherein the interpolation function operates 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.
A communication system for generating an OFDM signal having allocated frequency tones distributed over a predetermined bandwidth, the communication system comprising:
- a mapping module 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;
- and
- an interpolation module that receives the discrete signal and generates a digital signal sample vector by applying an interpolation function to the discrete signal;
- wherein the interpolation function operates on the discrete signal such that a frequency response of the digital signal sample vector includes sinusoids having non-zero values at the allocated frequency tones, and zero values at frequency tones other than the allocated frequency tones.
A communication system for generating an OFDM signal having allocated frequency tones distributed over a predetermined bandwidth, the communication system comprising:
- a mapping module 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;
- and
- an interpolation module that receives the discrete signal and generates a continuous signal by applying an interpolation function to the discrete signal;
- wherein the interpolation function operates on the discrete signal such that values of the continuous signal at the prescribed time instants are equal to the mapped symbols.
A communication system comprising:
- a mapping circuit that receives data symbols and maps the symbols to prescribed time instants in a time domain symbol duration to generate a discrete signal of mapped symbols;
- and
- an interpolation circuit that receives the discrete signal and generates a continuous signal by applying an interpolation function that operates on the discrete signal such that a frequency response of the continuous signal includes sinusoids having non-zero values at a first set of tones, and zero values at a second set of tones.
A communication system comprising:
- a mapping circuit that receives data symbols and maps the symbols to prescribed time instants in a time domain symbol duration to generate a discrete signal of mapped symbols;
- and
- an interpolation circuit that receives the discrete signal and generates a digital signal sample vector by applying an interpolation function that operates on the discrete signal such that a frequency response of the digital signal sample vector includes sinusoids having non-zero values at a first set of tones, and zero values at a second set of tones.
A communication system for generating an OFDM signal having a set of frequency tones distributed over a predetermined bandwidth, the communication system comprising:
- 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;
- a DFT circuit that performs a discrete Fourier transform on the discrete signal to generate a frequency domain symbol vector representing a frequency response of the discrete signal at allocated tones;
- a zero insertion circuit that manipulates the frequency domain symbol vector by inserting zero value symbols at frequency tones other than the allocated tones;
- and
- an IDFT circuit that performs an inverse discrete Fourier transform to obtain a digital signal sample vector representing a continuous function.
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.
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;
- 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.
Dependencies are inferred from the claim text.