Crest factor reduction cancellation pulse having a reduced length
Techniques are disclosed for the use of Crest Factor Reduction (CFR) technique that utilizes a cancellation pulse signal having a reduced length. The CFR technique may be applied to a signal to be transmitted, which may comprise a composite signal having one or more carrier signals. Each carrier signal of the composite signal may be filtered via a respective channel filter and then recombined to form the signal to be transmitted, on which the CFR operations are then applied. The length of the cancellation pulse signal is less than the number of taps of the channel filter with the largest number of taps. This reduction in cancellation pulse signal length significantly reduces the processing power required to perform the CFR operations while maintaining regulatory emissions compliance.
1 . A non-transitory computer-readable medium configured to store instructions that, when executed by processing circuitry, cause the processing circuitry to perform crest factor reduction (CFR) by:
generating a scaled cancellation pulse signal comprising a first set of data samples; and
performing CFR by subtracting the first set of data samples from a second set of data samples associated with a CFR input signal, to thereby generate a transmit signal,
wherein the CFR input signal comprises a carrier signal that is filtered via a channel filter having a frequency response based upon a predetermined bandwidth of the carrier signal,
wherein the scaled cancellation pulse signal is (i) separate from the CER input signal, and (ii) generated using simulated channel filter parameters that differ from filter parameters used by the channel filter to filter the carrier signal, and
wherein a number of the first set of data samples is less than a number of taps of the channel filter.
2 . The non-transitory computer-readable medium of claim 1 , wherein the instructions are executed via a programmable processing array to perform the CFR on the CER input signal to generate the transmit signal.
3 . The non-transitory computer-readable medium of claim 1 , wherein the scaled cancellation pulse signal has a spectral response that is contained within a bandwidth of the carrier signal.
4 . The non-transitory computer-readable medium of claim 1 , wherein:
the CFR input signal comprises a composite signal comprising a plurality of carrier signals that include the carrier signal,
the plurality of carrier signals are filtered via a respective one of a plurality of channel filters, each one of the plurality of channel filters having a respective number of taps, and
the number of the first set of data samples is less than the number of taps of a respective one of the plurality of channel filters having the largest number of taps.
5 . The non-transitory computer-readable medium of claim 1 , wherein the transmit signal complies with boundaries defined by a predetermined spectral mask.
6 . The non-transitory computer-readable medium of claim 1 , wherein (i) a spectral response of the CFR input signal, and (ii) a spectral response of the scaled cancellation pulse signal, are different from one another.
7 . The non-transitory computer-readable medium of claim 1 , wherein a spectral response of the CFR input signal is identical to a spectral response of the scaled cancellation pulse signal except at spectral edges of the CFR input signal and the scaled cancellation pulse signal.
8 . A system on a chip (SoC), comprising:
a channel filter configured to perform channel filtering on a carrier signal of a CER input signal in accordance with a number of filter taps, the channel filter having a frequency response that is based upon a predetermined bandwidth of the carrier signal; and
processing circuitry configured to perform crest factor reduction (CFR) on the CFR input signal by:
generating a scaled cancellation pulse signal comprising a first set of data samples; and
subtracting the first set of data samples from a second set of data samples associated with the CFR input signal, to thereby generate a transmit signal,
wherein the scaled cancellation pulse signal is (1) separate from the CFR input signal, and (ii) generated using simulated channel filter parameters that differ from filter parameters used by the channel filter to filter the carrier signal, and
wherein the number of the first set of data samples is less than the number of filter taps.
9 . The SoC of claim 8 , wherein the processing circuitry comprises part of an application specific integrated circuit (ASIC).
10 . The SoC of claim 8 , wherein the processing circuitry comprises part of a field programmable gate array (FPGA).
11 . The SoC of claim 8 , wherein the scaled cancellation pulse signal has a spectral response that is contained within a bandwidth of the carrier signal.
12 . The SoC of claim 8 , wherein:
the CFR input signal comprises a composite signal comprising a plurality of carrier signals that include the carrier signal,
the plurality of carrier signals are filtered via a respective one of a plurality of channel filters, each one of the plurality of channel filters having a respective number of taps, and
the number of the first set of data samples is less than the number of taps of a respective one of the plurality of channel filters having the largest number of taps.
13 . The SoC of claim 8 , wherein the transmit signal complies with boundaries defined by a predetermined spectral mask.
14 . The SoC of claim 8 , wherein (i) a spectral response of the CFR input signal, and (ii) a spectral response of the scaled cancellation pulse signal, are different from one another.
15 . The SoC of claim 8 , wherein a spectral response of the CFR input signal is identical to a spectral response of the scaled cancellation pulse signal except at spectral edges of the CFR input signal and the scaled cancellation pulse signal.
16 . A wireless device, comprising:
channel processing circuitry comprising a channel filter configured to perform channel filtering on a carrier signal of a CER input signal in accordance with a number of filter taps, the channel filter having a frequency response that is based upon a predetermined bandwidth of the carrier signal; and
transmitter circuitry configured to perform crest factor reduction (CFR) on the CFR input signal by:
generating a scaled cancellation pulse signal comprising a first set of data samples; and
subtracting the first set of data samples from a second set of data samples associated with the CFR input signal, to thereby generate a transmit signal,
wherein the scaled cancellation pulse signal is (i) separate from the CER input signal, and (ii) generated using simulated channel filter parameters that differ from filter parameters used by the channel filter to filter the carrier signal, and
wherein the number of the first set of data samples is less than the number of filter taps.
17 . The wireless device of claim 16 , wherein the scaled cancellation pulse signal has a spectral response that is contained within a bandwidth of the carrier signal.
18 . The wireless device of claim 16 , wherein:
the CER input signal comprises a composite signal comprising a plurality of carrier signals that include the carrier signal,
the plurality of carrier signals are filtered via a respective one of a plurality of channel filters, each one of the plurality of channel filters having a respective number of taps, and
the number of the first set of data samples is less than the number of taps of a respective one of the plurality of channel filters having the largest number of taps.
19 . The wireless device of claim 16 , wherein the transmit signal complies with boundaries defined by a predetermined spectral mask.
20 . The wireless device of claim 16 , wherein (i) a spectral response of the CER input signal, and (ii) a spectral response of the scaled cancellation pulse signal, are different from one another.
21 . The wireless device of claim 16 , wherein a spectral response of the CFR input signal is identical to a spectral response of the scaled cancellation pulse signal except at spectral edges of the CER input signal and the scaled cancellation pulse signal.