A new Double Two-Way Ranging algorithm for ranging system

For wireless positioning system, a study on two-way ranging algorithms has been progressed to improve the accuracy of position estimates. In this paper, we propose an asynchronous Double Two-Way Ranging (D-TWR) algorithm, executing an overlapped Two-Way Ranging (TWR) effectively. In this way, the D-TWR algorithm can reduce the number of the required packets in the ranging algorithm as compared with that of the Symmetric Double Sided Two-Way Ranging (SDS-TWR) algorithm. Moreover, D-TWR can achieve more robust Time-of-Arrival (TOA) estimation than SDS-TWR by reducing the TOA estimation errors caused by clock crystal drift between two nodes.