Spreading and precoding in OFDM
First Claim
1. A transmitter configured to reside in a User Equipment (UE), comprisinga 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).
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Accused Products
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.
292 Citations
26 Claims
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1. 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). - View Dependent Claims (2, 3, 4, 5, 6)
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7. 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). - View Dependent Claims (8, 9, 10, 11, 12)
- and a memory coupled to the processor, the memory including instructions stored therein and executable by the processor to;
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13. 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). - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. 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). - View Dependent Claims (21, 22, 23, 24, 25, 26)
- and a memory coupled to the processor, the memory including instructions stored therein and executable by the processor to;
Specification