Mitigating inter-cell interference in 5G ultra-dense femtocell networks: Issues and challenges

Due to the popularity of data-hungry devices, like smart phones and tablets, the mobile operators towards the Fifth Generation (5G) are driven not only to increase their network capacity but also to boost the life of such battery operated wireless smart devices. One of the most feasible solutions to cope with this is the evolution from traditional macro-cell deployments to network densification. Small cells are seen as the best match for network densification, as they can be opportunistically deployed in the highly irregular way in hot spots. In consequence, the deployment of dense femtocell networks (DFNs) can be seen as an efficient spectrum utilization using new spectrum bands but subjected to inter-cell interference coordination. This presentation will discuss inter-femtocell interference scenarios in a typical femtocell cluster together with an overview of some of the available interference management techniques. Since densification of femtocells in an uncoordinated manner can lead to severe inter-femtocell interference, especially when they share the same channel and operate in Closed Subscriber Group (CSG) mode, a new Semi-virtual Clustering Scheme (SVCS) has been proposed. This scheme exploits users' status to categorize femtocells into the victim, aggressor or neutral and each victim femtocell is then partitioned into two virtual cells. Moreover, the scheme adapts dynamically to the status of each femtocell in the cluster, being either a victim or a safe femtocell and smartly estimates the proper partitioning (time or frequency) of resources within the defined clusters.