On the TAs reconfiguration problem in LTE networks

In LTE, tracking Areas (TAs) are used to group cells where each cell is assigned to one TA and each user equipment (UE) registers with one TA. A TA may be connected to more than one mobility management entity (MME), which records the current TAs of its UEs. The home subscriber server (HSS) records the current MME for each UE. When a UE moves to a new TA, a TA update procedure is triggered to update the MME in case of an intra-MME move and the HSS in case of an inter-MME move. When the UE is called, the paging procedure is triggered to determine the UE's current cell, by broadcasting a paging message in all cells of the UE's current TA. The smaller the TAs are, the smaller the number of cells needed to be paged but more often TA updates. On the other hand with a larger TA, the paging cost increases and the TAU signaling decreases. Hence designing TAs is a problem as it affects both paging and TAU signalling cost. An initial optimal TA configuration cannot guarantee a low signaling overhead because the UEs mobility might alter their distribution. Therefore, the TAs need to be reconfigured to account for the new distribution of UEs. In this paper, we use the Integer Programming Model to solve the TAs reconfiguration problem in LTE networks. We then evaluate the performance of the proposed approach and compare it to the tabu search and the genetic algorithm based solutions to study how far from optimality those solutions are.