An optimization approach to cell association and resource allocation in heterogeneous cellular networks

In heterogeneous cellular networks (HCNs), it is highly desirable to design a cell association strategy that can actively offload mobile users to less congested small cells. Such a cell association strategy needs to be considered in conjunction with resource allocation. In this paper we take an optimization approach to analyze joint cell association and resource allocation in a two tier HCN. We formulize a utility maximization problem with the square root function as the utility function, and with proper relaxation of constraints, we are able to solve this problem and obtain an optimal solution that improves network throughput. Numerical results show that our approach achieves load balancing across macro and small cell BSs, and provide higher network throughput compared to the max SINR and max log sum association schemes. Our results also show that the optimal solution takes a tradeoff between user fairness and network throughput.