Research And Implementation Of Optimized State Query Algorithms Between Moving Objects

With the wide application of wireless communication technology and smart mobile devices, location-based services (LBS) is widely used in areas such as military, transportation, logistics, medical and livelihood. By using a variety of positioning technology, location-based services can get the current location of mobile terminals, and then index and query the location information through mobile object management technology, which can provide users with personalized service. In recent years, the typical queries of mobile object management include range queries, nearest neighbor query, reverse nearest neighbor query, the farthest neighbor query, nearest neighbor query, continuous reverse nearest neighbor query. These services have achieved very good results after years of research, and the related technology is very mature. However, with the rapid development of the location-based service, some query services have appeared which focus on the positional state between the moving objects. To server users better, the state query between moving objects are becoming more and more important.Movement tends between moving objects can be classified to different classes. State query is a process of judging the state based on the distance between moving objects. Based on the concept of state query between moving objects, we have proposed plain algorithm and the other one based on ELM. We have optimized the two algorithms as following. For plain algorithm, we propose a new algorithm based on the maximum and minimum to distinguish ten categories by comparing the first distance and the maximum or minimum of all distances. For ELM algorithm, this paper not only chooses more discrimination characteristics, but also further optimizes the algorithm. The results show that time performance for optimized plain algorithm has improved by nearly half comparing with the original one. The optimized ELM algorithm is improved not only in query accurcy but also in time performance.After modeling the concept of continuous state query, we propose three kind of continuous state query algorithm between moving objects. The first one is based on the distance comparasion. When new time interval comes, we need to compare the new distance to all the past distance and update the matrix. Secondly, the query algorithm based on priority queue calculates the maximum and minimum of distances in time window by priority queue. To solve the missing of maximum and minimum when time window pushing, the third algorithm has brougt about the concept of candidate sequence, which avoids the problem effectively. This paper achieves these algorithms and compares them from different aspects. The results show that smaller time window is favor of the algorithm based on distance comparasion and larger time window is better for another two algorithms.