Pre-coding in multi-user MIMO
First Claim
Patent Images
1. 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.
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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.
313 Citations
24 Claims
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1. An OFDM transmitter, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method, comprising:
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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. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An apparatus comprising:
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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. - View Dependent Claims (23, 24)
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Specification