A collaborative integrity monitor algorithm for low space aviation under limited number of navigation satellites

This paper proposes a novel integrity monitoring method of satellite navigation signals under constraint environments. The method introduced in this paper utilizes measurements of multiple aircrafts via airspace peer to peer communication. Measurements of the same satellite from different aircrafts are collaborated to form fault detection statistic. A cascaded RAIM algorithm is designed to discriminate multiple outliers. Performance of the proposed algorithm is evaluated under different integrity and continuity allocation. Relationship between detection sensitivity and number of cooperative aircraft members is also analyzed for both single and double outlier condition. Experiments show that our proposed algorithm can greatly help to increase RAIM detection sensitivity. Detection probability reaches to almost 99.9% when four aircrafts are cooperated, compared to the poor detection probability of only below 20%, when the fault magnitude is four times of standard deviation. Relationship between number of cooperative aircrafts and integrity budget is also studied. It is demonstrated that with increase of cooperative aircrafts number, a lower missed detection probability can be achieved for high integrity. Detection of multiple outliers is also considered, and radical protection level is calculated for different number of aircrafts. The proposed work is valuable for navigation integrity monitoring under limited number of satellites.