“…Some structures focus on indexing the current locations of moving objects; for example, hashing [Song and Roussopoulos 2001a], the LUR-tree [Kwon et al 2002], the LUGrid , the CT-R-tree ], the R R -tree [Biveinis et al 2007], and the RP-tree [Lin et al 2006]. For indexing the current and future positions of moving objects, some methods are the TPR-tree [Saltenis et al 2000], the TPR*-tree [Tao et al 2003b], the VCI (see Section 5.3), the STP-tree [Tao et al 2004a], STRIPES [Patel et al 2004], the B x -tree ], the B dual -tree [Yiu et al 2008], the spacetime grid [Chon et al 2001b], the STAR-tree [Procopiuc et al 2002], or the proposal in [Aggarwal and Agrawal 2003] for non-linear trajectories. Finally, in [Lin et al 2005] and [Pelanis et al 2006], the BB x -index and the R P P F -tree, respectively, are proposed as integrated approaches to index the past, present and future locations of moving objects.…”