为提高多径信号的能量利用率，提出一种基于分数傅里叶变换（FrFT）的片内多径搜索方法．该方法使用Chirp信号作为导频信号，在接收端对多径Chirp信号进行分数傅里叶变换，根据多径时延差与分数域信号峰值的位置差之间的线性关系，通过检测分数域峰值位置计算出各多径分量的相对时延，搜索精度为Chirp信号带宽的倒数．当Chirp带宽大于扩频带宽时，可用于直扩接收机分辨片内多径．仿真结果表明，文中方法能有效地计算出片内多径时延，在采用等增益方式对片内多径进行合并后，直扩接收机的误码率性能提高

To improve the energy efficiency of muhipath signals, a subchip muhipath search method based on the fractional Fourier transform （FrFT） is proposed, in which Chirp signals are used as pilot signals and muhipath Chirp signals are processed by FrFT at receiver side. Then, according to the linear relationship between the multipath relative delay in time domain and the difference in peak positions of muhipath Chirp signals in FrFT domain, the relative delays between muhipath Chirps are calculated after detecting the peak positions, with a search resolution equal to the reciprocal of the bandwidth of Chirp signals. Thus, the Chirp signal with a bandwidth lager than that of direct sequence spread spectrum （DSSS） signal can be used to search subchip muhipath. Simulated results show that the proposed method helps to effectively calculate the relative delays of subchip multipath and greatly improves the BER （ Bit Error Rate） performance of DSSS receiver after the equal-gain-combining process of the recognized subchip multipath.