基于FFT特性增加相位序列的变换选择性映射方法

摘要

We propose novel Transformation Selected Mapping schemes (T-SLM), which are based on the properties of Fast Fourier Transform (FFT). The T-SLM schemes make use of generated phase sequences and the circular shift property, the linear property of FFT and combination of the two properties to construct T1,T2 andT21 transformations for generating more alternative candidate OFDM signals without increasing IFFT operations. We also deduce the analytical formula of complexity for SLM and T-SLM schemes. Theoretical analysis indicates that the proposed T-SLM scheme can remarkably reduce the computational complexity of obtaining the candidate signals without decreasing the PAPR reduction performance compared with the conventional SLM. The simulation results also show that T-SLM schemes outperform conventional SLM in the case of the same number of sub-blocks; and both schemes almost have the same performance for the same candidate number.However, T-SLM has less computational complex. In T-SLM with the same number of sub-blocks,T21 is prior to T1 andT2 for PAPR reduction performance.%本文提出了基于傅立叶变换(FFT)特性的变换选择性映射(T-SLM)方法.该方法利用已产生的相位序列和FFT的频域循环移位特性、线性特性及其联合特性构造出了T1、T2和T21三种变换以产生新的相位序列,增加更多交替的OFDM信号序列,而不是通过增加IFFT运算产生更多的备选信号序列;同时分析给出了反映文中各种SLM和T-SLM方法运算复杂度的解析式.理论分析表明本文提出的T-SLM方法有效降低了得到备选信号的计算复杂度,但并没有减少备选信号的数量,因而也没有减少PAPR降低的性能.仿真显示,在相同的子序列时,T-SLM方法的性能胜过SLM方法;在相同的备选信号时,T-SLM方法(T21)能很好地接近SLM方法的性能,但减少了计算复杂度;在相同的子序列数时,本文提出的T-SLM方法使用T21变换要优于使用T1和T2变换.