Timing Tracking Algorithms for Impulse Radio (IR) Based Ultra Wideband (UWB) Systems

Recently, we have proposed low power transceiver architectures for impulse radio (IR) based ultra wideband (UWB) systems. Low power consumption is achieved thanks to the low duty cycle of UWB-IR signals, which allows to switch on the radio front-ends only for the instants where UWB pulses must be transmitted or received. Therefore, accurate synchronization of the receiver´s timing reference with the incoming UWB signal´s timing is critical in this context to avoid dramatic performance loss. Before data demodulation, the receiver´s timing reference is usually aligned with the incoming signal´s timing by using timing acquisition algorithms that rely on a known preamble. However, during data demodulation that is after timing acquisition algorithms, the offset between the crystal oscillators used at the transmitter and receiver still causes the receiver´s timing reference to gradually drift away from the incoming signal´s timing. In this paper, we first show that this problem causes dramatic performance degradation if not addressed. We then propose three low-complexity algorithms that allow tracking and compensating for the timing drift in our low duty-cycle context. Our simulation results show that the proposed algorithms are able to cope with the offset corresponding to the accuracy of typical crystal oscillators with minimal performance degradation. Moreover, one of the proposed algorithms is able to partially compensate for potential errors of timing acquisition algorithms that result in misalignments of the incoming UWB signal´s timing and receiver´s timing reference at the start of data demodulation.