Title: Caching Meets Millimeter Wave Communications for Enhanced Mobility Management in 5G Networks,
Abstract: One of the most promising approaches to overcome the uncertainty and dynamic
channel variations of millimeter wave (mmW) communications is to deploy
dual-mode base stations that integrate both mmW and microwave ($\mu$W)
frequencies. If properly designed, such dual-mode base stations can enhance
mobility and handover in highly mobile wireless environments. In this paper, a
novel approach for analyzing and managing mobility in joint $\mu$W-mmW networks
is proposed. The proposed approach leverages device-level caching along with
the capabilities of dual-mode base stations to minimize handover failures,
reduce inter-frequency measurement energy consumption, and provide seamless
mobility in emerging dense heterogeneous networks. First, fundamental results
on the caching capabilities, including caching probability and cache duration
are derived for the proposed dual-mode network scenario. Second, the average
achievable rate of caching is derived for mobile users. Third, the proposed
cache-enabled mobility management problem is formulated as a dynamic matching
game between mobile user equipments (MUEs) and small base stations (SBSs). The
goal of this game is to find a distributed handover mechanism that subject to
the network constraints on HOFs and limited cache sizes, allows each MUE to
choose between executing an HO to a target SBS, being connected to the
macrocell base station (MBS), or perform a transparent HO by using the cached
content. The formulated matching game allows capturing the dynamics of the
mobility management problem caused by HOFs. To solve this dynamic matching
problem, a novel algorithm is proposed and its convergence to a two-sided
dynamically stable HO policy is proved. Numerical results corroborate the
analytical derivations and show that the proposed solution will provides
significant reductions in both the HOF and energy consumption by MUEs.