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Context-Aware Decoupled Multiple Association in Ultra-Dense Networks

The new trends in network denisification, heterogeneity, and the introduction of new techniques (e.g., full-duplex) introduce new challenges for user association. For most existing user association schemes, the uplink (UL) and downlink (DL) access are coupled. That is, a user equipment (UE) is associated with the same BS for UL and DL transmissions. However, in ultra-dense heterogeneous networks (UDNs), due to the large disparities among base stations in different tiers and among uplink and downlink, the coupled UL-DL user association will limit the system performance. In this paper, we propose a novel concept of decoupled multiple association for user association in UDNs, which allows a UE to be associated with multiple base stations (BSs) for UL and DL in a decoupled manner. Furthermore, the context information of UEs is considered when making association decisions. Specifically, a decoupled multiple association matching game is formulated and a context-aware swap matching algorithm is proposed. The proposed scheme could attain higher data rates and could satisfy the quality of service (QoS) requirements of different UEs. Additionally, it could overcome the back-haul limitation of individual BSs. We compare the proposed scheme with three other association schemes, and the simulation results show significant performance gains of our proposed scheme in UDNs.