Reducing Congestion in Two-tier Cellular Network Using Multi-Relay D 2 D Communications

Due to the large increase of mobile devices called User Equipments (UEs), that connect to cellular networks, it may be impossible for a user to satisfy data communication if a large number of them are connected to a Base Station (BS). We propose a congestion mitigation method as one solution to this problem. Our proposed method transfers traffic to neighboring non-congested Base Stations using Device-to-Device (D2D) communications. As a result, the number of UE connections within the coverage area of the BS can be increased. In this paper, we propose a method for two-tier cellular networks composed of a macrocell and picocells which are within the coverage area of the macrocell. When the macrocell BS is congested, some of the UE connections to the macrocell BS are forwarded to a noncongested picocell BS using multi-relay D2D communications. We evaluated the performance of our proposed method by simulation. The simulation results have shown that the number of UEs that can be connected to BSs can be increased using multi-relay D2D communications.