Global Optimization of Weighted Sum-Rate for Downlink Heterogeneous Cellular Networks

It is envisioned that Heterogeneous cellular network is key technology in 5G that can be used to meet the ever increasing demand of data rate. The most critical problem of HetNet is interference. One of our objectives is to design beamformers to mitigate interference and achieve the maximum throughput while satisfying some power and interference constraints. In this paper we are able to determine the global solution of the non-convex NP-hard weighted sum-rate problem using branch and bound method. It involves searching for the best individual rates among many feasible rates achievable in the system that maximizes the weighted sum-rate of the system while fulfilling the power and interference constraints. Results obtained show that our proposed method outperformed other methods such as egoistic beamforming method and the relaxed convex optimization heuristic method which produces sub-optimal solution to the original non-convex problem.