In order to improve the accuracy of time delay estimation in wireless channel measurements under multipath conditions

a combination of matched filtering

Method of Direction Estimation（MODE）

and Weighted Fourier transform and RELAXation based（WRELAX）are studied.This paper proposes a MODE with extra Roots

which is based on WRELAX（MODEX-WRELAX）algorithm.The corresponding algorithm derivation is also presented in this paper.The new algorithm can not only resolve multipath delay but also suppress noise and strong interference well.Simulation results show that this method provides higher accuracy and resolution than MODE

WRELAX

and MODE-WRELAX algorithms.It also shows that the MODEX-WRELAX algorithm can approach the corresponding Cramer-Rao Bound（CRB）.