A Low-Complexity Method for FFT-based OFDM Sensing假设sm(n)s_{m}(n)sm(n)表示第m(0,1,2,⋯ ,M−1)(0,1,2,\cdots,M-1)(0,1,2,⋯,M−1)个OFDM符号,存在N个数据符号需要发送。N个数据符号通过N个正交子载波发送,其中T=NTs,B=1/TsT=NT_s,B=1/T_sT=NTs,B=1/Ts,T为数据符号长度T=1/ΔfT=1/\Delta fT=1/Δf。则第m个符号第k个时域信号可表示如下: xm(k)=1N∑n=0N−1sm(n)ej2πnkTs/T=1N∑n=0N−1sm(n)ej2πnk/N