Modeling and Cost Analysis of an Improved Movement-Based Location Update Scheme in Wireless Communication Networks

A movement based location update (MBLU) scheme is an LU scheme, under which a user equipment (UE) performs an LU when the number of cells crossed by the UE reaches a movement threshold. The MBLU scheme suffers from ping-pong LU effect. The ping-pong LU effect arises when the UE that moves repetitively between two adjacent cells performs LUs in the same way as in the case of straight movement. To tackle the ping-pong LU effect encountered by the original MBLU (OMBLU) scheme, an improved MBLU (IMBLU) scheme was proposed in the literature. Under the IMBLU scheme, the UE performs an LU when the number of different cells, rather than the number of cells, visited by the UE reaches the movement threshold. In this paper we develop an embedded Markov chain model to calculate the signaling cost of the IMBLU scheme. We derive analytical formulas for the signaling cost, whose accuracy is tested through simulation. It is observed from a numerical study based on these formulas that 1) the signaling cost is a downward convex function of the movement threshold, implying the existence of an optimal movement threshold that can minimize the signaling cost, and that 2) the reduction in the signaling cost achieved by the IMBLU scheme relative to the OMBLU scheme is more prominent in the case of stronger repetitiveness in the UE movement. The model developed and the formulas derived in this paper can guide the implementation of the IMBLU scheme in wireless communication networks.