# A Hybrid PAPR Reduction Method Based on SLM and Multi-Data Block PTS for FBMC/OQAM Systems
## 5 Simulation Results
It is worth noting that increasing the numbers of \(U\) and \(V\) can significantly improve the performance of PAPR reduction, but it also brings the impact of increased computational complexity. In Figure 8, the PAPR reductions of the four methods with different numbers of data blocks are given, where \(U=4\) and \(V=4\). In SLM, PTS and simple SLM-PTS methods, the fewer data blocks scheme has a better performance of PAPR reduction. This is because that the greater the number of data blocks in the FBMC/OQAM signal, the greater the effect of signal overlapping. However, the more data blocks scheme outperforms the fewer data blocks scheme in the proposed method. The proposed method takes into account of the overlapping effects of multiple adjacent data blocks, so more data blocks do not lead to PAPR performance degradation. Figure 8: PAPR reductions by using the proposed method, the SLM, PTS and SLM-PTS methods with different numbers of data blocks. Figure 7: PAPR reductions by using the proposed method, the SLM, PTS and SLM-PTS methods with different numbers of \(U\) and \(V\). The PAPR reduction performances of the SLM-PTS and proposed methods with two classical filter banks are shown in Figure 9. The two classical filter banks are PHYDYA and square root raised cosine (SRRC) filter. In the SRRC filter bank, the roll-off factor is one, and the length of filter is 4\(T\). We can find that, when the same PAPR reduction scheme is used, the FBMC/OQAM system with SRRC can provide a slightly better performance of PAPR reduction than the FBMC/OQAM system with PHYDYAS. This may be due to the fact that SRRC has a better time-frequency characteristic, the overlapped structure has a weaker effect on the PAPR reduction of the SRRC filter bank. Figure 10 shows the BER comparisons of the four methods over the multipath channel with \(M=16\), \(U=4\) and \(V=4\) (i.e., the Pedestrian A (PA)). The channel model is four multipaths with delays of 0, 110, 190 and 410 ns, respectively, and relative powers of 0, -9.7, -19.2 and -22.8 dB, respectively. In the condition of the same signal noise ratio (SNR), the BER of original signal is the lowest, the BER of PTS method is slightly better than that of the SLM method. When \(BER=10^{-3}\), the SNR of proposed method increases by about 0.7 dB compared to the SLM-PTS method, increases by about 1.3 dB compared to the PTS method, and increases by about 1.4 dB compared to the SLM method. The proposed method outperforms the other three methods. Figure 10: BER performance comparisons between the proposed method, the SLM, PTS and SLM-PTS methods over the Pedestrian A (PA) channel. Figure 9: PAPR reductions by using the SLM-PTS and proposed methods with two different filter banks. As show in the simulation results, it can be verified that the proposed hybrid scheme has improved the PAPR reduction performance when compared with the two conventional schemes in FBMC/OQAM systems. The superiority of this method is due to the fact that the overlapped data block structure is considered in the joint PAPR reduction process. By reducing the peak of the overlapping signals, a better PAPR reduction effect can be achieved.