Peak power to average power ratio reduction in multicarrier communication systems using error-correcting code

Abstract

This invention pertains to multicarrier systems where the Peak power to Average power Ratio (PAR) is generally high, and where the system has a Forward Error Correction (FEC) mechanism. A peak detection mechanism, a procedure for choosing a subcarrier to be modified and a symbol modifier scheme are disclosed for lowering the peak power of a signal while minimizing coding errors. The peak detector uses a threshold for determining whether the PAR reduction is to be applied. A subcarrier symbol(s) to be modified is identified depending on the number of peaks in a frame, by determining the subcarrier symbol which has the maximum effect on the peaks in the frame. One method chooses the subcarrier with the greatest overall effect on a peak in the frame, a second method selects the subcarrier that gives the minimum sum of residual peaks, and a third method is limited to situations where there are only two peaks.