High-Accuracy TDOA-Based Localization without Time Synchronization

Abstract

Localization is of great importance in mobile and wireless network applications. Time Difference of Arrival (TDOA) is one of the widely used localization schemes, in which the target (source) emits a signal and a number of anchors (receivers) record the arriving time of the source signal. By calculating the time difference of different receivers, the location of the target is estimated. In such a scheme, receivers must be precisely time synchronized. But time synchronization adds computational cost, and brings errors which may lower localization accuracy. Previous studies have shown that existing time synchronization approaches using low-cost devices are insufficiently accurate, or even infeasible under high requirement for accuracy. In our scheme (called Whistle), several asynchronous receivers record a target signal and a successive signal that is generated artificially. By two-signal sensing and sample counting techniques, time synchronization requirement can be removed, while high time resolution can be achieved. This design fundamentally changes TDOA in the sense of releasing the synchronization requirement and avoiding many sources of errors caused by time synchronization. We implement Whistle on commercial off-the-shelf (COTS) cell phones with acoustic signal and perform simulations with UWB signal. Especially we use Whistle to localize nodes of large-scale wireless networks, and also achieve desirable results. The extensive real-world experiments and simulations show that Whistle can be widely used with good accuracy.

Opportunistic Time-of-Arrival localization in fully asynchronous wireless networks

“…[26]). Considering the problem of terrestrial (non GNSS) localization with time (not phase) measurement, the DTDoA principle first appeared a decade ago in the context of interferometry [27] and was later considered in systems where the time difference between two terrestrial signals from distinct transmitters is measured by waveform correlators [28,29]. This approach demands specialized processing at the physical layer and/or considerable additional capacity to exchange sampled waveforms between the nodes, therefore cannot be implemented on top of legacy devices.…”

Realization Limits of Impulse-Based Localization System for Large-Scale Indoor Applications

“…Like this, the time difference is measured at slave APs, always between the direct master signal and the pulse retransmitted by the MU. In this concept, further developed in [44], the TDOA measurements are carried out locally, relaxing the global timing constraints. This approach could also be described as bistatic two-way ranging.…”

On the performance of multi-GPU-based expert systems for acoustic localization involving massive microphone arrays

“…On the other hand, direct approaches per-form TDOA estimation and source localization in one single step by scanning a set of candidate source locations and selecting the most likely position as an estimate of the real source location. Although the computation of TDOAs usually requires time synchronization, new approaches are being developed to avoid this limitation (Xu et al, 2013). Most localization algorithms are based 20 on the Generalized Cross-Correlation (GCC) (Knapp & Carter, 1976), which is calculated by using the inverse Fourier transform of the weighted cross-power spectral density of the signals.…”