Distributed antenna system aided cross-tier interference management for small cell networks

We consider cross-tier interference management in heterogeneous networks with femtocells overlaid onto macrocells. We propose a variation of the cellular architecture and introduce a novel femtocell clustering to enhance the sum-rate capacity. Our proposal utilizes distributed antenna system (DAS) remote antenna units (RAUs) within a two-tier network. By placing an RAU in the vicinity of femtocells, the transmitted symbols of an interfering macrocell user equipment (MUE) can be recovered at the RAU and fed back to the femtocells affected by the interference of the MUE. We derive the aggregated interference at the RAU to assess the probability of successful reception of the symbols of the MUE under a femtocells and MUE clustering. Consequent to our proposal, the novel femtocell clustering leads to a cluster capacity increasing with the number of terminals constituting the clustering. In addition, the proposed clustering leads to the opportunistic proposal to dynamically switch the operating spectrum of the femtocells within a macrocell to an adjacent macrocell´s based on cross-tier interference from the users of the macrocells. Our simulation results show substantial improvements in network sum-rate capacity.