Multi-Block Joint Optimization for the Peak-to-Average Power Ratio Reduction of FBMC-OQAM Signals

Recently, the filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) has attracted increasing attention. However, most peak-to-average power ratio (PAPR) reduction schemes developed for orthogonal frequency division multiplexing (OFDM) signals are not effective for FBMC-OQAM signals, due to the overlapping structure of FBMC-OQAM signals. In this paper, we propose an improved partial transmit sequence (PTS) scheme by employing multi-block joint optimization (MBJO) for the PAPR reduction of FBMC-OQAM signals, called as MBJO-PTS scheme. In PTS scheme, one data block is divided into several subblocks and each subblock is multiplied by a phase rotation factor for the subblock. The PTS scheme searches over all combinations of allowed phase factors to lower the PAPR. Unlike existing PAPR reduction schemes of independently optimizing the data blocks, the MBJO-based scheme exploits the overlapping structure of the FBMC-OQAM signal and jointly optimizes multiple data blocks. Moreover, we develop two algorithms for the optimization problem in the MBJO-PTS scheme, including a dynamic programming (DP) algorithm to guarantee the optimal solution and avoid exhaustive search. Theoretical analysis and simulations show that the proposed MBJO-PTS scheme could provide a significant PAPR reduction in the FBMC-OQAM system, by exploiting the overlapping structure of the FBMC-OQAM signal. Employing the proposed DP algorithm, the FBMC-OQAM system with the proposed MBJO-PTS scheme even outperforms the OFDM system with the conventional PTS scheme by 0.9 dB at CCDF of 10^-3 in PAPR reduction, under the same number of subcarriers, modulation type and PTS parameters given in Section V.