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In this paper, a novel low-complexity time-of-arrival (TOA) estimation strategy and a conceptual receiver setup for ultrawideband (UWB) signals is proposed, and its performance is evaluated. The receiver consists of an analog peak detector followed by two RC filters with different time constants. From two exponentially decaying signals, the TOA of the first peak of the received signal is reconstructed. This solution requires simple signal processing and sampling rates on the order of only a few tens of megahertz. At the same time, the achieved range error is at centimeter level since the large signal bandwidth used is fully exploited. To allow for performance flexibility, a statistical framework is proposed in which results of multiple initial TOA estimates are combined into a final estimate. Impairments due to narrowband interference are investigated, and a coarse acquisition scheme based on maximum energy detection is described. This last step is required for proper operation of the TOA receiver. A link budget analysis, which is based on the FCC power limitations for UWB signals, shows that reliable ranging is feasible up to 300 m in line-of-sight situations and up to 60 m in non-line-of-sight cases. The presented solution avoids the main technological challenges, namely extremely high sampling rates and complex processing at the receiver, which currently limit practical implementations of high-precision UWB positioning systems.
Date of Publication: Nov. 2012