THE APPROXIMATION OF ERGODIC SUM-RATE AND ITS APPLICATION IN ULTRA-DENSE NETWORK

An ultra-dense network (UDN) is a candidate solution to support ultra-high traffic density for future mobile communication systems. In this paper, we first provide a new closed-form approximation to the ergodic sum-rate of ultra-dense networks, which is in a simple form and agrees well with the Monte Carlo simulation results. Second, with the help of the derived sum-rate approximation, we formulated a downlink small base station and user equipment (SBS-UE) pairing problem to maximize the ergodic sum-rate. By further approximation and problem reformulation, we then propose an SBS-UE pairing algorithm for ergodic sum-rate maximization. Simulation results show that the proposed SBS-UE user association achieves a significant gain in the ergodic sum-rate.