An Efficient Downlink Coordinated Beamforming for Heterogeneous Networks

In heterogeneous networks (HetNet), interference coordination techniques among cells have been widely investigated to reduce co-channel interference (CCI), which causes severe system performance degradation when a same channel is shared at both femtocells and macrocell. In this paper, we examine a coordinated beamforming technique to reduce downlink (from macrocell to femtocells) CCI and processing complexity. Using uplink sounding reference signal (SRS), we propose an efficient beamforming searching function for a macro-BS reducing feedback burden compared to conventional schemes. Simulation results are provided for performance comparison in terms of the spectrum efficiency of femtocells and system throughput.