Information Technology Journal1812-56381812-5646Asian Network for Scientific Information10.3923/itj.2011.127.133YinZhendongShiZhenguoQiGuoweiZhouYi12011101This study proposed a direct sequence ultra-wideband (DS-UWB) channel estimation method using Maximum Likelihood algorithm for the indoor dense multi-path UWB channel of preamble structure suggested in the proposal of IEEE P802.15.TG3a. The Normalized Mean Square Channel Estimation Error (NMSCEE) is employed to measure the performance of the estimation method. The effect of the estimation performance influenced by different assisted-pilot numbers and the different Gaussian waveforms as UWB monocycle is discussed in different SNR conditions. Due to Federal Communications Commission (FCC)’s limits, the order of the derivative Gaussian pulse should be 5 of more. The simulation results show that the estimation algorithm can achieve satisfying performance with 60 as the pilot number. And when the pilot number is less than 50, the fifth order Gaussian pulse is the best choice. If the pilot number is more than 50, the ninth order Gaussian pulse is suitable. The results can be as the references and the basis for the practical UWB system.]]>Yang, L.Q. and G.B. Giannakis,2004Win, M.Z. and R.A. Scholtz,2000Fontana, R.J.,2004Zhaogan, L., W. Liejun, Z. Taiyi and R. Yun,2007Lee, J.Y.,2010Dilmaghani, R., M. Ghavami and H. Aghvami,2004Alizad, A.R., B. Alipanahi, A. Ghasemi, M. Shiva, S.H. Jamali and S.E. Nader,2005Ertin, E., U. Mitra and S. Siwamogsatham,2001Zheng, Y.R. and C. Xiao,2009Takeda, K. and F. Adachi,2005Yung, Y.W., J.T. Chen and W.H. Fang,2001Yi, H., Y.S. Wang, X.Y. Zuo and Y.N. Zhang,2008Wang, Y.P. and K.H. Chang,2007