Hierarchical precoding for ultra-dense heterogeneous networks

The need for cell densification leads to inter-cell interference mitigation techniques known as coordinated multipoint (CoMP) transmission and reception. In this work, we demonstrate the limits from joint regularized zero-forcing pre-coding within a cluster of several macro and small-cell base stations. While studying the effects of heterogeneous power constraints in such a cluster of transmission nodes, we develop a hierarchical precoding solution which mitigates the inter-cell interference from the macro-cells caused at the users mainly served by the small-cells. Due to significantly reduced transmit power budget both, inter-small-cell interference as well as interference from small-cells caused at the macro users is of less importance and hence is not taken into account within the precoding algorithm.