Mobility-Driven Association Policies for Dense Wireless Networks

Abstract

The primary approach to increase coverage and capacity in infrastructure-based wireless networks is densification. Densification, however, presents a major challenge when serving mobile users, which is the overhead associated with the increased rate of base station handovers. Assuming a prior knowledge of a mobile’s trajectory and base stations’ locations, we formulate the problem of determining the sequence of handovers that optimize the trade-off between the mobile user’s perceived throughput and handover overheads in noise-limited environments. Under appropriate conditions, we show that the problem reduces to determining a maximum weight path in a directed acyclic graph induced by the mobile user’s trajectory. In practice, knowledge of a mobiles’ trajectory may be limited and one may also want to limit the handover complexity, whence we propose a new class of mobility-driven greedy association policies. The greedy policies are based on defining a handover support set, which constrains both the possible handovers and the complexity/information requirements. In a setting where base station locations follow a Poisson point process, we show that the performance of such handover processes follows a continuous-time Markov process which can be analyzed using complex variable techniques. This enables one to explore the optimization size/shape of the handover support set for mobility-driven greedy handover strategies and their relative performance compared to traditional association policies.