关键词: 跳时超宽带（TH-UWB）, Rake接收机, 最小均方（LMS）算法, 仿真

Abstract: In the Ultra-Wide-Band（UWB） wireless communication systems，the receiving structure is usually based on RAKE receiver.The channel estimation is essential to the accuracy of RAKE receiver.In this paper，a gradient-based variable step size LMS algorithm is proposed to track time-varying channels.Compared with the typical LMS algorithm，this improved LMS algorithm produces much smaller MSE and hence provides better channel estimation.The results also show that the LMS algorithm helps improve the performance of RAKE receiver and gets smaller bit error rate.

Key words: Timing Hopping Ultra Wide Band（TH-UWB）, rake receiver, Least Mean Square（LMS） algorithm, simulation