Software adaptable high performance multicarrier transmission protocol
View Patent ↗Techniques for reducing peak-to-average power in multicarrier transmitters employ peak cancellation with subcarriers that are impaired by existing channel conditions. The use of Carrier Interferometry (CI) coding further improves the effectiveness of peak reduction. CI coding can also be impressed onto pulse sequences in the time domain, which enhances spectral selection and facilitates peak-power control.
1. A carrier interferometry (CI) transmission system employing peak-to-average power ratio (PAPR)-reduction signaling, the CI transmission system including:
a symbol-mapping module adapted to allocate a predetermined number of data bits to a predetermined set of subchannels,
a CI coder adapted to perform at least one predetermined combination of data spreading and channel coding to produce a plurality of input symbols,
a carrier-generator module adapted to associate the input symbols with at least one set of subchannels and generate a corresponding time-domain sequence representing a data-payload signal, and
an unloaded channel-encoding module adapted to select unloaded subchannels for transmission of at least one PAPR-reduction signal.
2. The CI transmission system recited in claim 1 wherein the unloaded channel-encoding module is adapted to select and generate at least one unloaded subchannel for combining with the time-domain sequence when the time-domain sequence exceeds a predetermined power threshold.
3. The CI transmission system recited in claim 2 wherein the unloaded channel-encoding module is adapted to generate PAPR-reduction signals in unloaded subchannels and combine the PAPR-reduction signals with the time-domain sequence until the time-domain sequence power drops below a predetermined threshold.
4. The CI transmission system recited in claim 1 wherein the symbol-mapping module is adapted to generate unloaded subchannels by not loading subchannels that are comprised by adverse channel conditions.
5. The CI transmission system recited in claim 1 wherein the unloaded channel-encoding module is adapted to maintain the data-payload signal below a predetermined clipping threshold.
6. The CI transmission system recited in claim 1 wherein the unloaded channel-encoding module is adapted to combine the at least one PAPR-reduction signal with at least one of the plurality of input symbols and the data-payload signal.
7. The CI transmission system recited in claim 1 wherein the symbol-mapping module is adapted to cease loading at least one predetermined subchannel that is below at least one predetermined channel-quality metric such that the unloaded channel-encoding module is capable of selecting said predetermined subchannel for transmission of at least one PAPR-reduction signal.
8. The CI transmission system recited in claim 1 wherein the symbol-mapping module is adapted to allocate a predetermined number of data bits to at least one of a set of subchannels including space-frequency subchannels, space-time subchannels, CI phase-space subchannels, spatial sub-channels, and polarization subchannels.
9. The CI transmission system recited in claim 1 wherein the symbol-mapping module is further adapted to select which of a plurality of sequence permutations of the predetermined number of data bits results in the greatest reduction of PAPR in the data-payload signal.
10. A multicarrier transmission system adapted to reduce the effects of high peak-to-average power ratio (PAPR) including:
a carrier interferometry (CI) coder adapted to spread at least one data sequence with at least one set of CI codes for generating at least one set of CI-coded symbols,
a sub-carrier generator adapted to map the at least one set of CI-coded symbols onto a plurality of subcarriers,
a plurality of combiners adapted to combine sets of the plurality of carriers for producing a plurality of CI-coded time-domain sequences that are characterized by low PAPR, and
a plurality of power amplifiers coupled to the plurality of combiners, the amplifiers adapted to amplify the plurality of CI-coded time-domain sequences.
11. The multicarrier transmission system recited in claim 10 further including an amplified-signal combiner coupled to the plurality of power amplifiers.
12. The multicarrier transmission system recited in claim 11 wherein the amplified-signal combiner includes at least one of a set including an antenna, a waveguide, and a multi-port junction.
13. A multicarrier signal generator including:
a pulse-train generator adapted to generate a sequence of pulse waveforms having a predetermined spectrum,
a carrier interferometry (CI) coder capable of generating at least one CI code, and
a carrier selector coupled to the CI coder and the pulse-train generator, the carrier selector adapted to impress the at least one CI code onto the sequence of pulse waveforms to shape the predetermined spectrum.