Unified multi-carrier framework for multiple-access technologies
View Patent ↗A wireless communication system transmits data on multiple carriers simultaneously to provide frequency diversity. Orthogonality is provided by carrier interference, which causes a narrow pulse in the time domain corresponding to each transmitted data symbol. Selection of the frequency separation and phases of the carriers controls the timing of the pulses. Equivalently, pulse waveforms may be generated from an appropriate selection of polyphase sub-carrier codes. Time division of the pulses and frequency division of the carriers may be employed for multiple access. Received signals are processed by combining frequency-domain components corresponding to a desired user's allocated carriers. Individual data symbols are processed by providing polyphase decoding, matched filtering, or time-domain shifting the received carriers. Carrier Interferometry components may be used to build various signals corresponding to other transmission protocols.
1. A transmission system adapted to generate at least one multi-carrier signal, the transmission system including:
a carrier generator adapted to generate a plurality of orthogonal carrier frequencies allocated to at least one user,
a data source adapted to impress at least one data symbol onto the carriers,
a combiner adapted to combine the carriers to generate a time-domain waveform,
a phase-shift module adapted to provide at least one predetermined set of poly-phase offsets to the carriers for generating at least one Carrier Interferometry (CI) signal, the phase offsets adapted to map each data symbol to a pulse waveform generated from a superposition of the carriers and centered at a predetermined instant in time, and
an amplitude control system adapted to provide a gain profile to the offset carriers.
2. The transmission according to claim 1 , wherein said combiner comprises a transformer to transform the carriers to said time-domain waveform.
3. The transmission system of claim 1 , wherein the gain profile is a tapered-amplitude window with respect to a frequency domain.
4. The signal transmitter system of claim 1 , wherein the gain profile is compensation for flat fading of the carriers.
5. The signal transmission system of claim 1 , wherein the gain profile is pulse-amplitude modulation.
6. A receiver system adapted to process at least one multi-carrier signal, the receiver including:
a filter bank adapted to separate at least one time-domain signal into a plurality of frequency-domain components,
a phase-shift circuit adapted to prdvide the frequency-domain components with at least one set of phase offsets wherein each set of phase offsets corresponds to an orthogonal pulse centered at a predetermined instant in time, and
a combiner adapted to combine the phase offset frequency-domain components to produce at least one time-domain sequence of symbols.
7. The receiver system according to claim 6 , wherein said filter bank comprise a Fourier transform component.
8. The receiver according to claim 6 , wherein said combiner comprises at least two combiners.
9. A computer-readable medium containing computer program information that, when executed by a processor, cause the processor to implement a method for controlling a multi-carrier generator comprising:
providing at least one set of subcarriers allocated to at least one user in a network, and
providing at least one set of complex weights to the at least one set of subcarriers for mapping each of at least one data symbol to at least one carrier-superposition pulse centered at a predetermined instant in time
providing at least one gain profile to the at least one set of weighted subcarriers.
10. The computer readable-medium of claim 9 , wherein the gain profile is a tapered-amplitude window with respect to a frequency domain.
11. The computer readable-medium of claim 9 , wherein the gain profile is compensation for flat fading of the carriers.
12. The computer readable-medium of claim 9 , wherein the gain profile is pulse-amplitude modulation.
13. A signal transmitter, comprising:
a subcarrier allocation module configured for allocating a plurality of subcarriers to at least one user in a communications network,
a mapping module configured for generating a plurality of complex sub-carrier weights to be applied to the subcarriers for generating a plurality of weighted subcarriers, the weights adapted to map each of a plurality of data symbols to at least one of a plurality of pulses generated by a superposition of the plurality of weighted subcarriers, each pulse being centered at a predetermined instant of time, and
an amplitude control system configured for generating gain profile for each of the plurality of weighted subcarriers.
14. The signal transmitter of claim 13 , wherein the gain profile is a tapered-amplitude window with respect to a frequency domain.
15. The signal transmitter of claim 13 , wherein the gain profile is compensation for flat fading of the carriers.
16. The signal transmitter of claim 13 , wherein the gain profile is pulse-amplitude modulation.
17. A transmission method, comprising:
allocating a plurality of complex subcarriers to at least one user in a communications network,
applying a plurality of complex sub-carrier weights to the subearriers to generate a plurality of weighted subcarriers, the weights adapted to map each of a plurality of data symbols to at least one of a plurality of pulses generated by a superposition of the weighted subcarriers, each pulse being centered at a predetermined instant in time, and
applying a gain profile to each of the plurality of weighted subcarriers.
18. The signal transmission method of claim 17 , wherein the gain profile is a tapered-amplitude window with respect to a frequency domain.
19. The signal transmission method of claim 17 , wherein the gain profile is compensation for flat fading of the carriers.
20. The signal transmission method of claim 17 , wherein the gain profile is pulse-amplitude modulation.
21. A computer-readable medium containing computer program information that, when executed by a processor, causes the processor to implement a method for controlling a multi-carrier receiver comprising:
receiving at least one channel estimate,
generating at least one set of complex weights for at least one set of subcarrier components generated from a received signal,
weighting and applying a gain profile to the at least one set of subcarrier components,
combining the weighted and gain profiled sub-carrier components to produce a sequence of symbols that conveys at least one transmitted signal value.
22. The computer readable-medium of claim 21 , wherein the gain profile is a tapered-amplitude window with respect to a frequency domain.
23. The computer readable-medium of claim 21 , wherein the gain profile is compensation for flat fading of the carriers.
24. The computer readable-medium of claim 21 , wherein the gain profile is pulse-amplitude modulation.