Mitigating signaling congestion in LTE location management by overlapping tracking area lists

Avoiding signaling congestion is a key aspect in location management of cellular networks. The signaling load in this context corresponds to the use of location update and paging messages for tacking user equipments (UEs). Signaling congestion may occur due to many UEs behaving in a similar manner, e.g., massive and simultaneous UE mobility in a train movement scenario. For Long Term Evolution (LTE) networks, location management can be based on the use of tracking area lists (TALs), each being a list containing multiple tracking areas (TAs). In this paper, the scheme of using TALs with overlapping TAs is applied for signaling congestion mitigation. One or multiple TALs that potentially overlap are allocated to each cell, and the TALs are assigned to the UEs that make their location updates in the cell. We derive linear programming formulations for finding the optimal proportional use of overlapping TALs for congestion avoidance. The main advantage of our approach is that it does not require the collection of detailed UE mobility information apart from what is available to the network. We report numerical results for realistic scenarios. The optimization approach yields promising results for reducing signaling congestion, and the performance region of optimized overlapping TALs goes significantly beyond the capability of the conventional TA scheme.