Research on Optimal Paging in Movement-Based Location Management Scheme

Location management (LM), which is a challenging problem in personal communication service (PCS) networks, is used to track mobile terminals (MTs). Basically, it consists of two operations: location update and paging. Location update is a process in which the MT informs the network of its current location, while paging is a process in which the network searches for a called MT. There are three dynamic LM schemes, namely, time-based, distance-based, and movement-based LM schemes. The movement-based is simple to implement, in which each MT simply counts the number of cell boundary crossings and initiates location update when this number exceeds the predefined movement threshold. In the LM scheme used in the existing PCS networks such as GSM, a blanket paging is used that all the cells in a location area (LA) are simultaneously paged. This paging scheme consumes extra resources since the MT only stays in one cell of the paged LA consisting of a group of cells. Therefore, sequential paging schemes are proposed to overcome the drawback. In this paper, emphasis is put on optimal sequential paging for movement-based LM scheme. Both the probability distribution of an MT's moving distance and expected moving distance in a movement-based scheme are derived on the condition that the incoming calls form a Poisson process and the MT's cell residence time has exponential probability distribution. Besides, based on the derived statistics, an optimal sequential paging algorithm is proposed. Finally, numeric results show that it outperforms some well-known sequential paging schemes.