Reducing signaling overhead by overlapping tracking area list in LTE

Reducing the total signaling overhead of tracking and paging user equipments (UEs) is one of the most challenging problems in the study of location management of cellular networks. Since the introduction of the list concept by 3GPP standards for Long Term Evolution (LTE) networks, defeating some of the existing limitations of the conventional Tracking Area (TA) design has been expected. However, how to exploit this flexibility in the system, without the existence of UEs' mobility traces, is still an open problem. In this paper, first we modify the linear program (LP) formulation of the overlapping tracking area list (TAL) scheme, which previously was only used for mitigating signaling congestion, to fit the objective of minimizing the total signaling overhead of tracking area update (TAU) and paging in a network. Second, we analyze the solution characteristics of the LP model. Finally, we perform a justified evaluation of the overlapping TAL scheme and the conventional TA scheme on a large-scale network by using two methods for calculating the signaling overhead of the aggregated data. Our modified LP model configures overlapping TALs for each cell in the network with the purpose of minimizing the total signaling overhead of location management in LTE networks. Analytical results demonstrate that although the optimality of the TAL design is valid for a limited period of time, by overcoming the limitations of symmetric and transitive properties of the conventional TA scheme, the proposed overlapping TAL scheme is able to reduce the total signaling overhead compared to what ultimately is achievable by the conventional TA design.