Fast-tracking delay-locked loop for UWB communication systems

Maintaining the synchronization between receiver and transmitter in the presence of Doppler effect is considered as a major challenge for ultra-wideband (UWB) communication systems. Delay-Locked Loop (DLL) method is widely proposed to keep the satisfactory synchronization. In this paper, we modify the structure of DLL, using Internal Model Control (IMC). Unfortunately, primary simulation results confirm that the IMC-DLL has a high opportunity to lose tracking in the presence of Doppler effect. In order to solve this problem, we develop the IMC tracking structure by adding an adaptive filter block, which has a simple structure: one addition and one division operators. The simulation results confirm that the proposed IMC-DLL has better transient response, compared with the classical DLL.