Constrained Clipping For Peak-to-average Power Ratio (crest Factor) Reduction In Multicarrier Transmission Systems
Baxley, Robert J.
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Disclosed is a constrained clipping technique for reducing the peak-to-average power ratio (PAR) or crest factor of a multicarrier communications signal. This is a transmitter-side processing technique that does not impose any modification at the receiver. Constrained clipping achieves PAR reduction while simultaneously satisfying spectral mask and error vector magnitude (EVM) constraints that are specified by most modern communications standards. The constrained clipping technique includes two independent processing units, one to satisfy an in-band EVM constraint and the other to satisfy an out-of-band spectral constraint. Achievable PAR reduction results vary depending on a particular standard's requirements, but by using constrained clipping on a QPSK WiMax signal with 256 subcarriers, for example, a 4.5 dB PAR reduction at the 10?2 complementary cumulative distribution function (CCDF) level can be obtained.
- Georgia Tech Patents