(A) novel peak power reduction scheme for partial transmit sequence OFDM

Abstract

One disadvantage of orthogonal frequency division multiplexing (OFDM) is that multicarrier signals exhibit a large peak-to-average power ratio (PAPR). To overcome this drawback, many solutions have been proposed and investigated. One of them is the partial transmit sequence (PTS). PTS involves forming several disjoint subblocks of carriers and multiplying each by a common phase factor. The phase factors are optimized to minimize the peak signal power. Subblock partition for PTS is a method of dividing subcarriers into multiple disjoint subblocks. Generally, it can be classified into 3 categories: interleaved, adjacent, and pseudo-random subblock partition scheme. There is a trade-off between PAPR reduction performance and computational complexity in PTS. The interleaved scheme shows the worst performance of PAPR reduction and the lowest computational complexity among them, but the pseudo-random scheme presents the best performance and the highest complexity. In this thesis, a novel PAPR reduction scheme, termed interleave-and-transmit-first-L-sample (ITL) scheme, is proposed. As the name implies, this approach is mainly based on the interleaved subblock partition scheme. But, it not only improves PAPR reduction performance extensively compared to the original interleaved scheme, but also shows much better performance than the pseudo-random scheme. Furthermore, the scheme requires much lower computational complexity as the three conventional schemes at both the transmitter and the receiver. Therefore, the ITL scheme may be considered to be more suitable than the conventional ones.