Processing of multi-carrier signals before power amplifier amplification
View Patent ↗Embodiments for methods and apparatuses for processing a multi-carrier signal are disclosed. One method includes shaping a frequency spectrum of a multi-carrier transmit signal wherein an amplitude of a plurality of subcarriers of the multi-carrier transmit signal is increased relative to at least one other subcarrier of the multi-carrier transmit signal. The shaped frequency spectrum multi-carrier transmit signal is amplified with a power amplifier, wherein a power level of an output of the power amplifier is greater than a rated power level of the power amplifier.
1. A method of processing a multi-carrier signal, comprising:
shaping a frequency spectrum of a multi-carrier transmit signal wherein an amplitude of a plurality of subcarriers of the multi-carrier transmit signal is increased relative to at least one other subcarrier of the multi-carrier transmit signal;
amplifying the shaped frequency spectrum multi-carrier transmit signal with a power amplifier, wherein a power level of an output of the power amplifier is greater than a rated power level of the power amplifier.
2. The method of claim 1 , wherein the rated power level of the power amplifier is a maximum power of an output signal of the power amplifier that meets EVM and spectral mask limits for a standard compliant multicarrier transmit signal, wherein the standard compliant multicarrier transmit signal has not been subject to frequency spectrum shaping.
3. The method of claim 1 , wherein shaping the frequency spectrum of the multi-carrier transmit signal comprises increasing an amplitude of a first plurality of subcarriers relative to a second plurality of subcarriers, wherein the first plurality of subcarriers occupies frequencies that are closer to a center frequency of the multicarrier signal than the second plurality of subcarriers.
4. The method of claim 3 , wherein shaping the frequency spectrum of a multi-carrier transmit signal results in the amplified multicarrier signal complying with a spectral mask.
5. The method of claim 1 , wherein the amplified multicarrier signal does not exceed predetermined spectral mask limits.
6. The method of claim 1 , wherein the amplified multicarrier signal does not exceed a predetermined EVM limit.
7. The method of claim 1 , further comprising:
amplitude compressing a time-domain version of the multi-carrier transmit signal;
filtering the compressed shaped frequency spectrum multi-carrier transmit signal prior to amplifying the shaped frequency spectrum multi-carrier transmit signal with a power amplifier.
8. The method of claim 7 , wherein amplitude compressing the time-domain version of the multi-carrier transmit signal is responsive to in-phase (I) and quadrature-phase (Q) components of the time-domain version of the multi-carrier transmit.
9. The method of claim 8 , wherein amplitude compressing the time-domain version of the multi-carrier transmit signal comprises processing I and Q components of the time-domain version of the multi-carrier transmit signal utilizing a plurality of CORDIC operations.
10. A method of processing a multi-carrier signal of a subscriber prior to the multi-carrier signal being amplified by a power amplifier of the subscriber, comprising:
shaping a frequency spectrum of a multi-carrier transmit signal wherein an amplitude of a plurality of subcarriers of the multi-carrier transmit signal is increased relative to at least one other subcarrier of the multi-carrier transmit signal;
amplifying the shaped frequency spectrum multi-carrier transmit signal with a power amplifier, wherein a power level of an output of the power amplifier is greater than a rated power level of the power amplifier.
11. The method of claim 10 , wherein shaping the frequency spectrum of the multi-carrier transmit signal comprises increasing an amplitude of a first plurality of subcarriers relative to a second plurality of subcarriers, wherein the first plurality of subcarriers occupies frequencies that are closer to a center frequency of the multicarrier signal than the second plurality of subcarriers.
12. The method of claim 10 , further comprising selectively utilizing the frequency spectrum shaping and operation of the power amplifier above its rated power level.
13. The method of claim 12 , wherein the frequency spectrum shaping and operation of the power amplifier above its rated power level is utilized during a wireless network entry procedure of the subscriber.
14. The method of claim 12 , wherein the frequency spectrum shaping and operation of the power amplifier above its rated power level is utilized for HARQ retransmission.
15. The method of claim 12 , wherein the frequency spectrum shaping and operation of the power amplifier above its rated power level is utilized when the subscriber is handing off from a first wireless base station to a second wireless base station.
16. The method of claim 12 , wherein the frequency spectrum shaping and operation of the power amplifier above its rated power level is utilized for a subset of the MCS levels available for transmission by the subscriber.
17. The method of claim 12 , wherein the frequency spectrum shaping and operation of the power amplifier above its rated power level is utilized for a subset of the transmission modes defined by a standard.
18. A method of processing a multi-carrier signal, comprising:
amplitude compressing a time-domain version of the multi-carrier transmit signal;
filtering the compressed multi-carrier transmit signal;
amplifying the compressed multi-carrier transmit signal with a power amplifier, wherein a power level of an output multi-carrier signal of the power amplifier is greater than a rated power level of the power amplifier.
19. The method of claim 18 , wherein the compression of the time-domain version of the multi-carrier transmit signal increases with an amplitude of the multi-carrier signal.
20. The method of claim 18 , wherein the amplitude compressing enables compliance with a spectral mask as measured at an output of the amplifier.
21. The method of claim 20 , wherein amplitude compressing the time-domain version of the multi-carrier transmit signal is responsive to in-phase (I) and quadrature-phase (Q) components of the time-domain version of the multi-carrier transmit.
22. The method of claim 21 , wherein amplitude compressing the time-domain version of the multi-carrier transmit signal preserves an angle of I and Q components of the time-domain version of the multi-carrier transmit.
23. The method of claim 21 , wherein amplitude compressing time-domain version of the multi-carrier transmit signal comprises processing I and Q components of the time-domain version of the multi-carrier transmit signal utilizing a plurality of CORDIC operations.
24. The method of claim 23 , wherein compressing the time-domain version of the multi-carrier transmit signal further comprising selecting between the processed I and Q components of the time-domain version of the multi-carrier transmit signal and the I and Q components of the time-domain version of the multi-carrier transmit signal.
25. The method of claim 18 , wherein amplitude compressing the time-domain version of the multi-carrier transmit signal comprises
applying a memory-less compressive nonlinearity function to the time-domain version of the multi-carrier transmit signal.
26. The method of claim 25 , wherein the memory-less compressive nonlinearity function limits a l p of the multi-carrier transmit signal.
27. The method of claim 25 , wherein the memory-less compressive nonlinearity function is a polyhedral norm.
28. The method of claim 25 , wherein the memory-less compressive nonlinearity function operates on a modulus of the time-domain version of the multi-carrier transmit signal.
29. A subscriber station, comprising:
circuitry operative to frequency spectrum shape a multi-carrier transmit signal wherein an amplitude of a plurality of subcarriers of the multi-carrier transmit signal is increased relative to at least one other subcarrier of the multi-carrier transmit signal; and
a power amplifier operative to amplifying the shaped frequency spectrum multi-carrier transmit signal, wherein a power level of an output multi-carrier signal of the power amplifier is greater than a rated power level of the power amplifier.
30. A transmitter, comprising:
means for shaping a frequency spectrum of a multi-carrier transmit signal wherein an amplitude of a plurality of subcarriers of the multi-carrier transmit signal is increased relative to at least one other subcarrier of the multi-carrier transmit signal;
means for amplifying the shaped frequency spectrum multi-carrier transmit signal with a power amplifier, wherein a power level of an output multicarrier signal of the power amplifier is greater than a rated power level of the power amplifier.