Cooperative Positioning Technology with Sea-Surface Wireless Sensor Networks

To satisfy the requirement of precise positioning and tracking for flying vehicle(FV) in times of exterior location datums(like GPS) outages or in these datums denied sea areas,a cooperative positioning technique(CPT) for the FV is proposed.First,the time of arrival(TOA)-based cooperative positioning algorithm(CPA) is presented after building station Cartesian coordinate system for cooperative positioning.Second,time synchronization among the nodes is crucial to guarantee CPT.Taking a single-hop S2WSN as an example,the problem of low synchronization precision,which is caused by ignoring unequal reply time in conventional round-trip timing(RTT) method in joint tactical information distribution system(JTIDS),is resolved by two-way timing with unequal reply time(TWT-UTD).Finally,a conceptual numerical simulation system is designed to verify the effectiveness of the proposed methods by Monte Carlo simulation over 1 000 runs.The simulation results show that the absolute bias of the FV tracking by the proposed CPA is superior to that of the conventional single ship-based relative positioning method through optimizing the position dilution of precision among the sea-surface nodes and the FV.Meanwhile,compared with the RTT method in JTIDS,the synchronization precision is increased by more than 20% via TWT-UTD method whilst the equivalent ranging error being reduced by 3 m.