The Design of Load Balancing Mechanism under Fractional Frequency Reuse for Heterogeneous Cellular Networks

Deploying some additional low-power base stations (BSs) into each macrocell is an efficient way to enhance the system capacity. However, this kind of deployment technique may lead to severe inter-cell interference (ICI) and unbalanced user distributions among BSs with different power, unless some additional strategies to tackle the problem are employed. To this end, we jointly consider the resource partitioning (i.e., fractional frequency reuse) and load balancing, and then design an association scheme with network-wide utility maximization. As for the formulated problem, we design a centralized association algorithm with pseudo-optimal solutions according to gradient descent method, and a low-complexity distributed association algorithm using dual decomposition. Numerical results show that the proposed association algorithms may bring interference avoidance and load balancing gains, which improve the performance of edge users while not degrading overall throughput.