OFDM系统中一种联合改进的低复杂度SLM峰均比抑制技术

高的峰值平均功率比(Peak-to-Average Power Ratio,PAPR)是光正交频分复用(Optical Orthogonal Frequency Division Multiplexing,O-OFDM)系统的一个主要缺点,选择性映射(Selective Mapping,SLM)法能有效降低高PAPR出现的概率,但它的计算复杂度较高.一些低复杂度的SLM方案能够有效地降低复杂度,但同时也降低了PAPR的抑制性能.为了平衡这两个因素,将低复杂度SLM方案与次优选择的思想相结合,文章提出了一种联合改进的PAPR抑制方案.在低复杂度方案中,通过将一个复频域信号分为两个实信号,再利用快速傅里叶变换(Fast Fourier Transform,FFT)的平移和反折性质将其重建成新的信号,以得到更多的备选信号,如此便能降低计算复杂度.然后,再结合次优选择的思想,选择PAPR最小的一路以得到最优的PAPR抑制性能.仿真结果验证了该方案的有效性.

A Joint improved SLM Scheme with Low Complexity of the PAPR Reduction Technology for O OFDM Systems

High peak to average power ratio (PAPR) is a major shortcoming of optical orthogonal frequency division multiplexing (O OFDM) system. The selective mapping (SLM) technology can effectively reduce the probability of high PAPR, but it has high computational complexity. Some low complexity SLM schemes can effectively reduce the complexity, but reduce the PAPR reduction performance. In order to balance the above two factors, a joint improved PAPR reduction scheme which combines a low complexity SLM scheme with the idea of suboptimal selection is proposed. In the low complexity scheme, through separating one complex signal into two real signals and utilizing the reversal and circular shift properties of fast Fourier transform (FFT) to reconstruct the new candidates, more candidate signals can be obtained. Thus the computational complexity can be reduced. Then, combining with the idea of suboptimal selection, the lowest PAPR is selected to obtain the optimized PAPR reduction performance. Simulation results have demonstrated the effectiveness of the proposed scheme.