Patent ID: 7738573

Claim:
A crest factor reduction system, the system comprising: a peak amplitude suppressor for suppressing peak amplitudes of an input signal X(n) relative to an average value of the input signal and providing a peak amplitude suppressed signal with a reduced peak-to-average ratio (PAR) in response thereto; said peak amplitude suppressor works on the input signal X(n), on a sample by sample basis, according to the following equation: X ( n )= X ( n ) if A ( n )< T X ( n )= X ( n )· T/A ( n ) if A ( n )≧ T where A(n) is an approximation of an amplitude of an nth sample of said input signal X(n) or A(n) is an amplitude of an nth sample of said input signal X(n) given by A(n)=√{square root over (real(X(n)) 2 +imag(X(n)) 2 )}{square root over (real(X(n)) 2 +imag(X(n)) 2 )}, T is a clipping threshold of the peak amplitude suppressor, and T/A(n) is a gain factor of the nth sample of X(n); and an intermodulation reject filter coupled to said peak amplitude suppressor for rejecting intermodulation distortion in said amplitude suppressed signal, said intermodulation reject filter's output being a peak suppressed version of said input signal, wherein said intermodulation reject filter is a single filter whose coefficients are derived from frequency shifting and adding coefficients of a baseband-designed filter for a single carrier, a baseband-designed filter for two adjacent carriers, a baseband-designed filter for three adjacent carriers, up to a baseband-designed filter for M adjacent carriers where a largest filter of the adjacent carriers is used wherever the adjacent carriers are present and each of the carriers falls in a passband of exactly one of the frequency-shifted baseband-designed filters.