Nearest Neighbor Query Technique Of Spatio-temporal Road Network

At present, in the field of computer appeared a lot of new applications, like positioning services.The appearing of these new applications, embodies the development of the wireless network communications, and other technical. In spatio-temporal database an important technology for query for positioning services is multi-types nearest neighbor query.Given a data set of n data types and a query point q, a multi-type nearest neighbour in spatio-temporal road network according to this given query point q ,find a optimal path, this path is composed of n data points that respectively belonged to different data typesAt present, most spatio-temporal data query are based on Euclidean distance between objects, such as the multi-types nearest neighbor query. But the reality is that of the distance between the objects are restricted by its network, like road network, aviation network, network, etc. Based on this, the measure of the distance between the objects should be the network distance according to its network.Based on thorough analysis on the basis of layered coding view,first , Contrary to the multi-type K nearest neighbor queries(MT-KNN) problem, combining the theory of multi-type nearest neighbor queries and K nearest neighbor query, a multi-type K nearest neighbor queries algorithm is put forward. Through a Hierarchical Encoded Path View is extended, make its every node containing a local path sequence with k data item,a multi-path Hierarchical Encoded View is established. By gradual growing the current partial path, the algorithm implements the multi-type K nearest neighbor queries. Then , Contrary to the multi-type nearest neighbor queries with time windows constraints (MT-TNN) problem, combining the theory of multi-type K nearest neighbor queries, a multi-type nearest neighbor queries with time windows constraints algorithm is put forward. Experimental results show that the algorithm has better perfomance.