Conceptual Study Of Mobile Differential Gnss Architecture Utilizing Uav Networks

Differential Global Navigation Satellite Systems (DGNSS) which feature rapid deployment and mobility can provide required navigation accuracy and integrity to a wide range of users at arbitrary locations where no permanently installed systems exist. This paper proposes a concept of mobile DGNSS whose reference stations are composed of multiple Unmanned Aerial Vehicles (UAVs) to facilitate mobility of system. Key algorithms of Mobile DGNSS architecture, developed in this work, include a decision making technical for selecting reference station location, a fast location surveying method and integrity monitors.Using the decision making technical, landing positions of UAV reference stations are selected by taking into account the geographical characteristics of the landing vicinity, and the distances from DGNSS service demands. To validate that the locations satisfy the minimum siting requirements upon landing, two tests are carried out: territorial inclination test for assuring a sufficient number of satellites in view and satellite visibility test for avoiding a harsh environment with obstacles. The fast location surveying method is developed to reduce the time taken for the determination of the surveyed positions within specific positional accuracy. The simulation results show that the proposed method enables users to achieve the desired positional accuracy in less amount of time than the general method of simply averaging stand-alone GNSS solutions only. Integrity monitors in addition to the well-established Ground Based Augmentation System (GBAS) monitors are developed to detect faults specific to the mobile DGNSS. The code multipath monitor and the station displacement monitor are designed to detect large multipath errors on code measurements and unexpected movements of the reference stations, respectively under uncontrolled siting conditions.Rapid start-up time is a critical factor to assess whether the proposed concept is feasible. We derive surveying position error budgets for different multipath environments and system architectures. A new Vertical Protection Level (VPL), which includes the bound of surveying errors, is defined for the mobile DGNSS users. The effect of the resulting surveying errors on the system is evaluated by estimating deployment time for various conditions.