continuous proximity monitoring in road networks
In this paper, we consider the following scenario: a set of mobile objects continuously track their positions in a road network and are able to communicate with a central server. The server which gets position updates from the moving objects has to detect the event that two objects reach or exceed a specified proximity distance. This way, the server is permanently aware of all pairs of objects that are within a certain distance range. Obviously, the communication costs between the objects and the server quickly become the bottleneck if a position update is sent to the server at each tracking time slot. We propose update strategies in order to reduce the communication overhead by defining special regions for each object. These regions are defined such that no position updates at the server are required as long as the objects do not leave their corresponding regions. We present efficient algorithms for updating these regions and detecting proximity/separation when objects leave their corresponding regions. Furthermore, we empirically evaluate the different strategies in terms of communication overhead, i.e. the number of required position updates.
proximity monitoring traffic networks