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 method of transmitting data, comprising:
mapping a predetermined amount of data to a predetermined set of subchannels;
performing carrier interferometry (CI) coding to provide at least one predetermined combination of data spreading and channel coding to obtain a plurality of input symbols;
associating the input symbols with at least one set of subchannels;
generating a corresponding time-domain sequence representing a data-payload signal, based on said associating; and
selecting one or more unloaded subchannels to be used for transmitting at least one peak-to-average power (PAPR) reduction signal.
2. The method according to claim 1 , wherein said selecting one or more unloaded subchannels comprises selecting and generating at least one unloaded subchannel when the time-domain sequence exceeds a predetermined power threshold.
3. The method according to claim 2 , further comprising:
generating at least one PAPR-reduction signal in at least one of said one or more unloaded subchannels; and
combining the at least one PAPR-reduction signal with the time-domain sequence until the time-domain sequence power drops below a predetermined threshold.
4. The method according to claim 1 , wherein said mapping includes generating one or more unloaded subchannels by not loading subchannels that are subject to adverse channel conditions.
5. The method according to claim 1 , wherein said selecting comprises maintaining the data-payload signal below a predetermined clipping threshold.
6. The method according to claim 1 , further comprising:
combining the at least one PAPR-reduction signal with at least one of the plurality of input symbols and the data-payload signal.
7. The method according to claim 1 , wherein said mapping comprises:
ceasing to load at least one predetermined subchannel that is below at least one predetermined channel-quality metric; and
wherein said selecting comprises selecting said predetermined subchannel for transmission of at least one PAPR-reduction signal.
8. The method according to claim 1 , wherein said mapping comprises:
allocating 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, or polarization subchannels.
9. The method according to claim 1 , wherein said mapping comprises:
selecting 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 method of transmitting data, comprising:
spreading at least one data sequence with at least one set of carrier interferometry (CI) codes to thereby generate at least one set of CI-coded symbols;
mapping the at least one set of CI-coded symbols onto a plurality of subcarriers;
combining sets of the plurality of carriers to produce a plurality of CI-coded time-domain sequences that are characterized by low peak-to-average power ratio (PAPR); and
amplifying the plurality of CI-coded time-domain sequences to thereby obtain a plurality of amplified signals.
11. The method according to claim 10 , further comprising:
combining the plurality of amplified signals to obtain a combined signal.
12. The method according to claim 11 , further comprising:
transmitting the combined signal over a transmission medium.
13. A method of generating a multi-carrier signal, the method comprising:
generating a sequence of pulse waveforms having a predetermined spectrum;
generating at least one carrier interferometry (CI) code; and
impressing the at least one CI code onto the sequence of pulse waveforms to shape the predetermined spectrum, to thus obtain an encoded sequence of pulse waveforms.
14. The method according to claim 13 , further comprising:
modulating the encoded sequence of pulse waveforms with data, to obtain a modulated signal.
15. The method according to claim 14 , further comprising:
transmitting the modulated signal over a multi-carrier communication channel.
16. A non-transitory computer-readable medium containing instructions that, when executed by at least one processor, cause the at least one processor to implement a method of transmitting data, the method comprising:
mapping a predetermined amount of data to a predetermined set of subchannels;
performing carrier interferometry (CI) coding to provide at least one predetermined combination of data spreading and channel coding to obtain a plurality of input symbols;
associating the input symbols with at least one set of subchannels;
generating a corresponding time-domain sequence representing a data-payload signal, based on said associating; and
selecting one or more unloaded subchannels to be used for transmitting at least one peak-to-average power (PAPR) reduction signal.
17. The medium according to claim 16 , wherein said selecting one or more unloaded subchannels comprises selecting and generating at least one unloaded subchannel when the time-domain sequence exceeds a predetermined power threshold.
18. The medium according to claim 17 , wherein the method further comprises:
generating at least one PAPR-reduction signal in at least one of said one or more unloaded subchannels; and
combining the at least one PAPR-reduction signal with the time-domain sequence until the time-domain sequence power drops below a predetermined threshold.
19. The medium according to claim 16 , wherein said mapping includes generating one or more unloaded subchannels by not loading subchannels that are subject to adverse channel conditions.
20. The medium according to claim 16 , wherein said selecting comprises maintaining the data-payload signal below a predetermined clipping threshold.
21. The medium according to claim 16 , wherein the method further comprises:
combining the at least one PAPR-reduction signal with at least one of the plurality of input symbols and the data-payload signal.
22. The medium according to claim 16 , wherein said mapping comprises:
ceasing to load at least one predetermined subchannel that is below at least one predetermined channel-quality metric; and
wherein said selecting comprises selecting said predetermined subchannel for transmission of at least one PAPR-reduction signal.
23. The medium according to claim 16 , wherein said mapping comprises:
allocating 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, or polarization subchannels.
24. The medium according to claim 16 , wherein said mapping comprises:
selecting 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.
25. A non-transitory computer-readable medium containing instructions that, when executed by at least one processor, cause the at least one processor to implement a method of transmitting data, the method comprising:
spreading at least one data sequence with at least one set of carrier interferometry (CI) codes to thereby generate at least one set of CI-coded symbols;
mapping the at least one set of CI-coded symbols onto a plurality of subcarriers;
combining sets of the plurality of carriers to produce a plurality of CI-coded time-domain sequences that are characterized by low peak-to-average power ratio (PAPR); and
amplifying the plurality of CI-coded time-domain sequences to thereby obtain a plurality of amplified signals.
26. The medium according to claim 25 , wherein the method further comprises:
combining the plurality of amplified signals to obtain a combined signal.
27. The medium according to claim 26 , wherein the method further comprises:
transmitting the combined signal over a transmission medium.
28. A non-transitory computer-readable medium containing instructions that, when executed by at least one processor, cause the at least one processor to implement a method of generating a multi-carrier signal, the method comprising:
generating a sequence of pulse waveforms having a predetermined spectrum;
generating at least one carrier interferometry (CI) code; and
impressing the at least one CI code onto the sequence of pulse waveforms to shape the predetermined spectrum, to thus obtain an encoded sequence of pulse waveforms.
29. The medium according to claim 28 , wherein the method further comprises:
modulating the encoded sequence of pulse waveforms with data, to obtain a modulated signal.
30. The medium according to claim 29 , wherein the method further comprises:
transmitting the modulated signal over a multi-carrier communication channel.