Interference Management in Ultra-Dense Networks: Challenges and Approaches

Capable of enhancing spatial multiplexing and greatly expanding network capacity, network densification has undoubtedly become a general trend in future wireless networks. However, in addition to the expected advantages, the overuse of spatial resources would result in unpredictable and overwhelming interference as well due to the limited spectrum resources and highly disorganized network infrastructures. Hence, a critical issue arises: are conventional IM techniques still applicable and effective to tackle the interference in UDN? To shed light on the problem, in this article we first investigate the characteristics of interference in UDN and then provide an overview of the existing dominant IM techniques. It is found that, due to the complicated interference, most IM techniques designed for sparse networks would lose their merits when applied in UDN. To reap their potential benefits, we design an IM entity for UDN, aided by which an adaptive on-off power control method is proposed. Results reveal that network capacity could be significantly improved using the proposed method, especially in UDN. In addition, open issues and challenges for IM co-design with stateof- the-art communications technologies are highlighted to provide insight on the potential direction in future wireless networks.