Major challenges in ultrawideband (UWB) communications include timing acquisition, tracking, and low complexity demodulation. Timing with dirty templates (TDT) is a recently proposed acquisition algorithm with attractive features. Starting with a performance analysis of TDT, this paper goes on to considerably broaden its scope by developing novel tracking loops and detectors by naturally following the TDT operation. Specifically, upper bounds on the mean square error of the blind and data-aided TDT estimators are derived, along with TDT-based demodulators, obviating the need to know the underlying channel and time hopping code. Analytical comparisons reveal that TDT demodulators outperform RAKE with limited number of fingers in the medium-high SNR range. TDT demodulation performance in the presence of timing errors is evaluated and shown to be robust to mistiming. In order to follow timing offset variations, an adaptive loop is also introduced to track the first multipath arrival of each symbol. For a given input disturbance, parameters of the loop are selected to optimize jointly transient and steady state performance. Analytical results are corroborated by simulations.
Bibliographical noteFunding Information:
Manuscript received February 19, 2005; revised June 1, 2005. The review of this paper was coordinated by Prof. X. Shen. This work was supported through collaborative participation in the Communications and Networks Consortium sponsored by the U.S. Army Research Laboratory under the Collaborative Technology Alliance Program, Cooperative Agreement DAAD19-01-2-0011. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation thereon. This work is also supported by the NSF-ITR Grant No. EIA-0324864. Part of the results in this paper were submitted to GLOBECOM Conf., St. Louis, MO, Nov. 28-Dec. 2, 2005; and ICU Conf., Zurich, Switzerland, Sept. 5–8, 2005.
- RAKE receiver
- Time lock loops
- Timing offset estimation
- Tracking performance
- Ultra-wideband (UWB)