Peak-to-average-power reduction for OFDM multiple access
AssigneeTybalt, LLC
InventorSteve Shattil
Life of this patent
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Abstract
An Orthogonal Frequency Division Multiplexing (OFDM) transmitter generates OFDM multiple-access signals with low Peak-to-Average-Power Ratio (PAPR). A code-division multiplexer arranges original data symbols from different data streams inside each length-N symbol block, which is spread by a Discrete Fourier Transform (DFT) spreader. The arrangement of the original data symbols configures the DFT spreader to spread each original data symbol into a predetermined spread-DFT code division multiple access channel. The resulting DFT-spread data symbols are mapped to OFDM subcarriers, and an inverse discrete Fourier transform (IDFT) operates on the DFT-spread data symbols to generate an OFDM transmission signal having low PAPR.
Claims27
An apparatus, comprising:
- a code-division multiplexer configured to assign a different codeword set to each of a plurality of data streams, each codeword set comprising a different one of a plurality of spread-Discrete Fourier Transform (DFT) code division multiple-access channels;
- a DFT spreader configured to spread the each of the plurality of data streams with its assigned codeword set to produce a plurality of DFT-spread data symbols;
- a mapper configured to map the plurality of DFT-spread data symbols to a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers;
- an inverse discrete Fourier transform (IDFT) configured to modulate the plurality of DFT-spread data symbols onto the plurality of OFDM subcarriers to generate an OFDM signal;
- and
- a cyclic-prefix appender configured to append a cyclic prefix to the OFDM signal to produce a transmission signal;
- wherein the code-division multiplexer and the DFT spreader configure the OFDM signal to have a low peak-to-average-power ratio (PAPR);
- and wherein the cyclic-prefix appender produces the cyclic prefix from the OFDM signal to provide the transmission signal with a low PAPR.
A method, comprising:
- multiplexing each of a plurality of data streams into a different one of a plurality of spread-Discrete Fourier Transform (DFT) code division multiple-access channels by assigning a different DFT codeword set to each of the plurality of data streams;
- spreading the each of the plurality of data streams with its assigned DFT codeword set to produce a plurality of DFT-spread data symbols;
- mapping the plurality of DFT-spread data symbols to a plurality of Orthogonal Frequency Division Multiplexing (OFDM) subcarriers;
- modulating the plurality of DFT-spread data symbols onto the plurality of OFDM subcarriers to generate an OFDM signal;
- and
- appending a cyclic prefix to the OFDM signal to produce a transmission signal;
- wherein the multiplexing and the spreading configure the OFDM signal to have a low peak-to-average-power ratio (PAPR);
- and wherein the appending produces the cyclic prefix from the OFDM signal to provide the transmission signal with a low PAPR.
An Orthogonal Frequency Division Multiplexing (OFDM) transmitter apparatus configured to generate an OFDM multiple-access signal, the transmitter apparatus comprising at least one processor, at least one memory in electronic communication with the at least one processor, and instructions stored in the at least one memory, the instructions executable by the at least one processor to:
- multiplex each of a plurality of data streams into a different one of a plurality of spread-Discrete Fourier Transform (DFT) code division multiple-access channels by assigning a different DFT codeword set to each of the plurality of data streams;
- spread the each of the plurality of data streams with its assigned DFT codeword set to produce a plurality of DFT-spread data symbols;
- map the plurality of DFT-spread data symbols to a plurality of OFDM subcarriers;
- modulate on the plurality of DFT-spread data symbols onto the plurality of OFDM subcarriers to generate an OFDM signal;
- and
- append a cyclic prefix to the OFDM signal to produce a transmission signal, wherein the instructions executable by the at least one processor to multiplex and spread configure the OFDM signal to have a low peak-to-average-power ratio (PAPR), and the cyclic prefix being produced from the OFDM signal to provide the transmission signal with a low PAPR.
Dependencies are inferred from the claim text.