Spectrum shaping crest factor reduction

A crest factor reduction (CFR) system comprising:

• a controller configured to:
• receive a signal for radio transmission;
• adjust CFR processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein the controller configured to adjust the CFR processing characteristics is configured to adjust the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• and
• apply CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• an amplifier to amplify the resultant modified signal,
• wherein the controller configured to apply the CFR processing with the adjusted CFR processing characteristics is configured to:
• generate a subtraction pulse using the adjusted CFR processing characteristics based, at least in part, on the received signal;
• and
• subtract the subtraction pulse from the received signal to produce the resultant modified signal;
• wherein the controller configured to generate the subtraction pulse is configured to adjust one or more pulse properties defining the subtraction pulse such that the modified signal resulting from subtracting the subtraction pulse substantially optimally occupies the spectral space under the pre-determined spectral envelope.

A non-transitory computer readable media programmed with a set of computer instructions executable on a processor that, when executed, cause the operations comprising:

• receiving a signal for radio transmission;
• adjusting crest factor reduction (CFR) processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein adjusting the CFR processing characteristics comprises adjusting the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• applying CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• amplifying the resultant modified signal;
• wherein applying the CFR processing with the adjusted CFR processing characteristics comprises:
• generating a subtraction pulse using the adjusted CFR processing characteristics based, at least in part, on the received signal, including adjusting one or more pulse properties defining the subtraction pulse such that the modified signal resulting from subtracting the subtraction pulse substantially optimally occupies the spectral space under the pre-determined spectral envelope;
• and
• subtracting the subtraction pulse from the received signal to produce the resultant modified signal.

A method comprising:

• receiving a signal for radio transmission;
• adjusting crest factor reduction (CFR) processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein adjusting the CFR processing characteristics comprises adjusting the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• applying CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• amplifying the resultant modified signal;
• wherein applying the CFR processing with the adjusted CFR processing characteristics comprises:
• processing the received signal by a filter chain comprising one or more CFR stages that each includes a respective peak detector coupled, at an output of the respective peak detector, to a respective finite impulse response (FIR) filter with adjustable coefficients optimized subject to the constraint that the output signals generated at an output of the filter chain are bound by the pre-determined spectral mask.

A crest factor reduction (CFR) system comprising:

• a controller configured to:
• receive a signal for radio transmission;
• adjust CFR processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein the controller configured to adjust the CFR processing characteristics is configured to adjust the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• and
• apply CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• an amplifier to amplify the resultant modified signal;
• wherein the controller comprises:
• a filter chain, configured to apply to the received signal the CFR processing with the adjusted CFR processing characteristics, the filter chain comprising one or more CFR stages that each includes a respective peak detector coupled, at an output of the respective peak detector, to a respective finite impulse response (FIR) filter with adjustable coefficients optimized subject to the constraint that the output signals generated at an output of the filter chain are bound by the pre-determined spectral mask.

A method comprising:

• receiving a signal for radio transmission;
• adjusting crest factor reduction (CFR) processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein adjusting the CFR processing characteristics comprises adjusting the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• applying CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• amplifying the resultant modified signal;
• wherein adjusting the CFR processing characteristics according to the one or more optimization criteria for the output signals generated based on the adjusted CFR processing characteristics comprises:
• producing the resultant modified signal according to one of:
• a criterion that minimizes a computed error vector magnitude (EVM) for the resultant modified signal for a given peak-to-average power ratio (PAPR);
• or
• another criterion that minimizes a peak-to-average power ratio (PAPR) for a given error vector magnitude (EVM) for the resultant modified signal.

A crest factor reduction (CFR) system comprising:

• a controller configured to:
• receive a signal for radio transmission;
• adjust CFR processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein the controller configured to adjust the CFR processing characteristics is configured to adjust the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• and
• apply CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• an amplifier to amplify the resultant modified signal;
• wherein the controller configured to adjust the CFR processing characteristics according to the one or more optimization criteria for the output signals generated based on the adjusted CFR processing characteristics is configured to produce the resultant modified signal according to one of:
• a criterion that minimizes a computed error vector magnitude (EVM) for the resultant modified signal for a given peak-to-average power ratio (PAPR);
• or
• another criterion that minimizes a peak-to-average power ratio (PAPR) for a given error vector magnitude (EVM) for the resultant modified signal.

A method comprising:

• receiving a signal for radio transmission;
• adjusting crest factor reduction (CFR) processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein adjusting the CFR processing characteristics comprises adjusting the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• applying CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• amplifying the resultant modified signal;
• wherein adjusting the CFR processing characteristics according to the one or more optimization criteria comprises:
• selecting one or more CFR processing characteristics from a list of controllable attributes that includes at least one of:
• pulse length, number of peak trackers, number of CRF stages, at least one hard clipping factor representing the amount of crest factor reduction in each of a series of stages, peak qualification window size representative of a smallest time separation of peaks that are cancelled, number of iterations of shape optimization, number of starting shapes for the optimization, objective to be optimized, pulse shape factor with a value between 0 and 1 that is used to form a smooth discrete time function that mimics the shape of a bandpass filter spectrum for the band in which the pulse will be used, a band stretch ratio with a value ρ between −1/2 and 1/2 which determines the factor (1+ρ) by which the basic spectrum band is stretched, or band relative weight factor with a number f between 1/2 and 3/2 that is used for multi-band configurations to determine how to distribute compensation scale factor between two or more bands;
• assigning pre-determined values to non-selected CFR processing characteristics from the list of controllable attributes;
• and
• iteratively computing values for the selected one or more CFR processing characteristics, based on the non-selected CFR processing characteristics assigned with the pre-determined values, that achieve spectrum packing inside the pre-determined spectral mask.

A crest factor reduction (CFR) system comprising:

• a controller configured to:
• receive a signal for radio transmission;
• adjust CFR processing characteristics applied to the received signal to modify one or more portions of the signal according to a pre-determined spectral mask representative of a frequency envelope limiting allowed magnitudes for frequency components bounded by the spectral mask, wherein the controller configured to adjust the CFR processing characteristics is configured to adjust the CFR processing characteristics according to one or more optimization criteria for output signals generated based on the adjusted CFR processing characteristics, and subject to a constraint that the output signals generated based on the adjusted CFR processing characteristics are bound by the pre-determined spectral mask;
• and
• apply CFR processing with the adjusted CFR processing characteristics to the received signal to produce a resultant modified signal;
• and
• an amplifier to amplify the resultant modified signal;
• wherein the controller configured to adjust the CFR processing characteristics according to the one or more optimization criteria is configured to:
• select one or more CFR processing characteristics from a list of controllable attributes that includes at least one of:
• pulse length, number of peak trackers, number of CRF stages, at least one hard clipping factor representing the amount of crest factor reduction in each of a series of stages, peak qualification window size representative of a smallest time separation of peaks that are cancelled, number of iterations of shape optimization, number of starting shapes for the optimization, objective to be optimized, pulse shape factor with a value between 0 and 1 that is used to form a smooth discrete time function that mimics the shape of a bandpass filter spectrum for the band in which the pulse will be used, a band stretch ratio with a value ρ between −1/2 and 1/2 which determines the factor (1+ρ) by which the basic spectrum band is stretched, or band relative weight factor with a number f between 1/2 and 3/2 that is used for multi-band configurations to determine how to distribute compensation scale factor between two or more bands;
• assign pre-determined values to non-selected CFR processing characteristics from the list of controllable attributes;
• and
• iteratively compute values for the selected one or more CFR processing characteristics, based on the non-selected CFR processing characteristics assigned with the pre-determined values, that achieve spectrum packing inside the pre-determined spectral mask.