부산대학교 도서관

Cellular networks are becoming increasingly heterogeneous with higher base station (BS) densities and ever more frequency bands, making BS selection and band assignment key decisions in terms of user service rate and coverage. In this paper, we decompose the mobility-aware user association task into (i) forecasting of user data rate and then (ii) convex utility maximization for user association accounting for the effects of BS load and handover overheads. Using a linear combination of normalized mean-squared error (NMSE) and normalized discounted cumulative gain (NDCG) as a novel loss function, a recurrent deep neural network is trained to reliably forecast the mobile users’ future data rates. Based on the forecast, the controller optimizes the association decisions to maximize the service rate-based network utility using our computationally efficient (speed up of $100\times $ versus generic convex solver) algorithm based on the Frank-Wolfe method. Using an industry-grade network simulator developed by Meta, we show that the proposed model predictive control (MPC) approach improves the 5th percentile service rate by $3.5\times $ compared to the traditional signal strength-based association, reduces the median number of handovers by $7\times $ compared to a handover agnostic strategy, and achieves service rates close to a genie-aided scheme. Furthermore, our model-based approach is significantly more sample-efficient (needs $100\times $ less training data) compared to model-free reinforcement learning (RL), and generalizes well across different user drop scenarios.