PAPR reduction in OFDM systems using differentially encoded subcarriers

A peak-to-average power ratio (PAPR) reduction technique that exploits the principle of differential encoding of subcarriers is proposed and investigated. The absolute maximum sample of the time-domain OFDM symbol is chosen as the reference to carry out the differential encoding process at the transmitter. A real multiplier (??) is applied to this reference to achieve appropriate PAPR level. Information about the proposed reference, however, is required to be communicated to the receiver, which performs the reverse effect to obtain back the original sequence of samples. The effectiveness of the proposed technique is evaluated through extensive computer simulations and complementary cumulative distribution function (CCDF) are obtained as a function of number of subcarriers and modulations. Numerical results confirm that significant reduction in PAPR can be achieved. For example, the proposed technique reduces the 0.1 percent PAPR to 1.5 dB for a 1024 subcarrier OFDM system, resulting in 10.3 dB reduction. Moreover, error performances of the OFDM system before and after applying the proposed technique are investigated using Monte Carlo simulations. Numerical results show that the average bit error rate performance of the proposed system does not degrade relative to the un-encoded system. An investigation of the complexity of the proposed technique with other techniques show that it is quite low complex.