A Linear Transform Approach for PAPR Reduction in OFDM Signals by PTS using Segmented and Iterative Phase Weighting Factors

Orthogonal Frequency Division Multiplexing (OFDM) is one of the attractive technology for wireless communications with Multi-Carrier Modulation (MCM) technique offers a considerable multipath delay spread tolerance, high spectral efficiency, immunity to the frequency selective fading channels and power efficiency. High Peak-to-Average Power Ratio (PAPR) of the transmit signal is a major drawback of multicarrier transmission such as OFDM. Partial Transmit Sequence (PTS) is one of the commonly used schemes to reduce the PAPR. Conventional Partial Transmit Sequence (C-PTS) requires an exhaustive searching over all combinations of the given phase factors, which results in exponential increase to the computational complexity with the number of sub blocks. In this paper, we aim to obtain the desirable PAPR reduction with the low computational and phase search complexity. PTS based phase weighting techniques with low computational complexity, named Segmented Phase Weighting (SPW) and Iterative Phase Weighting (IPW), are proposed. On applying one of the linear transformation techniques called circular time shift to the candidate sequences obtained by SPW and IPW method, high PAPR reduction can be obtained. This system will slightly increase the computational complexity but greater reduction in PAPR. At the receiver, by utilizing the natural diversity of phase constellation for different candidates, the detector can successfully recover the original signal without Side Information (SI). PAPR reduction performance of both proposed schemes are analyzed, the simulation results show that the proposed Circular Time Shifted- Segmented Phase Weighting (CTS-SPW) and Circular Time Shifted- Iterative Phase Weighting (CTS-IPW) schemes achieve better PAPR reduction compared to the C-PTS scheme.