Efficient OFDM PAPR reduction method using linear phase variation

An efficient OFDM peak to average power ratio (PAPR) reduction method using linear phase variation is proposed. Applying linear phase variations to subblocks of subcarriers is equal to cyclic shifting the corresponding time signals and thus can prevent “peak collisions”. This method differs from conventional partial transmit sequence (PTS) techniques in that PTS applies constant phase variations to subblocks. Performance comparison of linear phase variation, constant phase variation and tone reservation with the same number of redundant bits is conducted with 8, 52, and 128-subcarrier QPSK-OFDM signals. Linear phase variation achieves the best PAPR reduction performance in our simulations. Exhaustive test in the 8-subcarrier case when the subcarriers are partitioned into two equal-sized subblocks of consecutive subcarriers shows that all quaternary length 8 Golay sequences are selected with linear phase variation whereas 1/4 are selected for constant phase variation. Boolean function decomposition of the variation sequence provides explanation for this phenomenon. The above has been simulated by using Matlab tool and successfully implemented.