1. An exhaust emission control device for an internal combustion engine, comprising:
a three-way catalyst located in an exhaust channel of an internal combustion engine, wherein:
said three-way catalyst comprises one or more catalyst elements and has two or more pore groups different in average pore opening size in a washcoat.
2. The exhaust emission control device for an internal combustion engine according to claim 1, wherein:
said three-way catalyst comprises a microporous catalyst element having a micropore group whose average pore opening size is smaller than prescribed size in a washcoat and a macroporous catalyst element having a macropore group whose average pore opening size is larger than said prescribed size in a washcoat.
3. The exhaust emission control device for an internal combustion engine according to claim 2, wherein:
said three-way catalyst comprises a microporous catalyst element having a micropore group whose average pore opening size is smaller than molecular size of HC in a washcoat and a macroporous catalyst element having a macropore group whose average pore opening size is larger than the molecular size of HC in a washcoat.
4. The exhaust emission control device for an internal combustion engine according to claim 2, wherein:
said microporous catalyst element and said macroporous catalyst element are arranged in series with each other, facing in a direction of an exhaust flow.
5. The exhaust emission control device for an internal combustion engine according to claim 4, wherein:
said microporous catalyst element is disposed on the upstream side of the exhaust flow, and said macroporous catalyst element on the downstream side of the exhaust flow.
6. The exhaust emission control device for an internal combustion engine according to claim 2, wherein:
said microporous catalyst element and said macroporous catalyst element are arranged in layers.
7. The exhaust emission control device for an internal combustion engine according to claim 6, wherein:
said microporous catalyst element is disposed on a surface layer side, and said macroporous catalyst element on an internal layer side.
8. The exhaust emission control device for an internal combustion engine according to claim 1, further comprising:
air-fuel ratio modulating means for periodically modulating an air-fuel ratio of an exhaust emission that flows into said three-way catalyst between a lean air-fuel ratio and a rich air-fuel ratio.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
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.