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US 9,628,231 B2Granted
Spreading and precoding in OFDM
AssigneeGenghiscomm Holdings, LLC
InventorSteve Shattil
Life of this patent
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Abstract
An OFDM transmitter spreads original data symbols with a complex-valued spreading matrix derived from a discrete Fourier transform. Spread data symbols are mapped to OFDM subcarriers. Spreading and mapping are configured to produce a transmitted spread-OFDM signal with a low peak-to-average power ratio (PAPR) and orthogonal code spaces. In MIMO systems, the complex-valued spreading matrix can comprise a MIMO precoding matrix, and the code spaces can comprise MIMO subspaces. In Cooperative-MIMO, a combination of low code-space cross correlation and low PAPR can be achieved.
Claims26
A transmitter configured to reside in a User Equipment (UE), comprising
- a discrete Fourier transform (DFT) spreader configured to spread a block of original data symbols with a DFT-based spreading matrix comprising a plurality of orthogonal spreading codes to produce a plurality of spread data symbols;
- a subcarrier mapper responsive to channel-dependent scheduling that assigns a set of uplink orthogonal frequency division multiplex (OFDM) subcarriers to the UE, the subcarrier mapper configured to map each of a plurality of non-zero data symbols to one of the set of uplink OFDM subcarriers, the plurality of non-zero data symbols comprising the plurality of spread data symbols;
- and
- an inverse-DFT configured to modulate the plurality of non-zero data symbols onto the set of uplink OFDM subcarriers to generate an OFDM signal for transmission into a wireless wide area network (WWAN);
- wherein at least one of the DFT spreader and the subcarrier mapper configures the plurality of non-zero data symbols to reduce the OFDM signal's peak-to-average-power ratio (PAPR).
2 more elements
A transmitter comprising a processor;
- and a memory coupled to the processor, the memory including instructions stored therein and executable by the processor to:
- spread a block of original data symbols with a discrete Fourier transform (DFT)-based spreading matrix comprising a plurality of orthogonal spreading codes to produce a plurality of spread data symbols;
- responsive to channel-dependent scheduling that assigns a set of uplink orthogonal frequency division multiplex (OFDM) subcarriers to the UE, map each of a plurality of non-zero data symbols to one of the set of uplink OFDM subcarriers, the plurality of non-zero data symbols comprising the plurality of spread data symbols;
- and
- modulate the plurality of non-zero data symbols onto the set of uplink OFDM subcarriers to generate an OFDM signal for transmission into a wireless wide area network (WWAN);
- wherein the DFT-based spreading matrix is configured to reduce the OFDM signal's peak-to-average-power ratio (PAPR).
3 more elements
A transmitter configured to reside in a User Equipment (UE), comprising
- a discrete Fourier transform (DFT) spreader configured to spread a block of original data symbols with a DFT-based spreading matrix comprising a plurality of orthogonal spreading codes to produce a plurality of spread data symbols;
- a subcarrier mapper responsive to scheduling that assigns a set of uplink orthogonal frequency division multiplex (OFDM) subcarriers to the UE, the subcarrier mapper configured to map each of a plurality of non-zero data symbols to one of the set of uplink OFDM subcarriers, the plurality of non-zero data symbols comprising the plurality of spread data symbols;
- and
- an inverse-DFT configured to modulate the plurality of non-zero data symbols onto the set of uplink OFDM subcarriers to generate an OFDM signal for transmission into a wireless wide area network (WWAN);
- wherein at least one of the DFT spreader and the subcarrier mapper configures the spread data symbols to reduce the OFDM signal's peak-to-average-power ratio (PAPR).
2 more elements
A transmitter comprising a processor;
- and a memory coupled to the processor, the memory including instructions stored therein and executable by the processor to:
- spread a block of original data symbols with a discrete Fourier transform (DFT)-based spreading matrix comprising a plurality of orthogonal spreading codes to produce a plurality of spread data symbols;
- responsive to channel-dependent scheduling that assigns a set of uplink orthogonal frequency division multiplex (OFDM) subcarriers to the UE, map each non-zero spread data symbols to one of the set of uplink OFDM subcarriers, the plurality of non-zero data symbols comprising the plurality of spread data symbols;
- and
- modulate the plurality of non-zero data symbols onto the set of uplink OFDM subcarriers to generate an OFDM signal for transmission into a wireless wide area network (WWAN);
- wherein the DFT-based spreading matrix is configured to reduce the OFDM signal's peak-to-average-power ratio (PAPR).
3 more elements
Dependencies are inferred from the claim text.