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US 9,485,063 B2Granted
Pre-coding in multi-user MIMO
AssigneeGenghiscomm Holdings, LLC
InventorSteve Shattil
Life of this patent
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Abstract
In a multi-user communication system, a pre-coder in a transmitter comprises a Discrete Fourier Transform (DFT) spreader configured to spread reference-signal symbols with Fourier coefficients to generate DFT-spread reference symbols. An OFDM modulator, such as an inverse-DFT, modulates the DFT-spread reference symbols onto OFDM subcarriers to produce a pre-coded OFDM transmission signal.
Claims24
An OFDM transmitter, comprising:
- an OFDM spreader configured to spread a plurality of reference-signal symbols with Fourier coefficients to generate a Discreet Fourier Transform (DFT)-spread reference signal;
- a mapper configured to map the DFT-spread reference signal to a plurality of OFDM subcarriers;
- and
- an OFDM modulator configured to modulate the DFT-spread reference signal onto the plurality of OFDM subcarriers to produce an OFDM transmission signal, wherein the OFDM transmission signal comprises a superposition of the OFDM subcarriers, and wherein the OFDM spreader is configured to provide the superposition with at least one predetermined time-domain signal characteristic comprising at least one of a plurality of uniformly spaced pulse waveforms and a signal with low peak-to-average power ratio.
1 more element
A method, comprising:
- generating at least one reference-signal symbol;
- multiplying a plurality of data symbols by a Discrete Fourier Transform (DFT) spreading matrix to produce a plurality of DFT-spread symbols, the plurality of data symbols comprising the at least one reference-signal symbol;
- mapping the plurality of DFT-spread symbols to a plurality of OFDM subcarriers;
- and
- modulating the plurality of DFT-spread symbols onto a plurality of OFDM subcarriers to produce a DFT-spread OFDM signal, wherein the DFT-spread OFDM signal comprises a superposition of the OFDM subcarriers, and wherein the DFT spreading matrix is configured to provide the superposition with at least one predetermined time-domain signal characteristic comprising at least one of a plurality of uniformly spaced pulse waveforms and a signal with low peak-to-average power ratio.
2 more elements
An 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:
- for a set of data symbols of a reference signal, perform an N-point discrete Fourier transform (DFT) spreading on the set of data symbols to generate a plurality N of DFT-spread components of the data symbols;
- map the N DFT-spread components to N subcarriers of a plurality M of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers to generate a set of complex subcarrier amplitudes;
- and
- perform an M-point inverse discrete Fourier transform (IDFT) on the set of complex subcarrier amplitudes to generate a time-domain sequence comprising a plurality M of discrete time-domain values, wherein the time-domain sequence comprises a superposition of the OFDM subcarriers, and wherein the N-point DFT spreading is configured to provide the superposition with at least one predetermined time-domain signal characteristic comprising at least one of a plurality of uniformly spaced pulse waveforms and a signal with low peak-to-average power ratio.
4 more elements
Dependencies are inferred from the claim text.