Cost-efficient hardware and synchronization for TDoA localization base stations

Localization has become an increasingly important feature for Internet of Things (IoT) devices over the last few years. Time-of-Flight (ToF)-based localization techniques can be performed energy efficiently for the mobile device but depend on synchronized base stations for the reception of the mobile devices signals. This contribution presents cost-efficient hardware for localization base stations based on software-defined radios (SDRs) and an automatic method of synchronizing multiple of the proposed base stations. Our proposed system allows coherent reception at multiple base stations suitable for localization purposes. The achieved level of synchronization exceeds the requirement for Time-Difference of Arrival (TDoA)-based localization methods. An illustrative implementation has been performed and the achieved coherence was evaluated.