On Minimizing Energy Consumption in FiWi Enhanced LTE-A HetNets

As an integration of optical fiber networks and LTE-A heterogeneous networks (HetNets), fiber-wireless (FiWi) enhanced LTE-A HetNets will play a key role in supporting large-scale mobile data transmission. To improve the energy efficiency of the networks, we should put as much equipment into sleep state, and thus few user equipment (UE) can access Internet. In contrast, to maximize the UE connection all equipment should be in active state, which results in very high energy consumption. Obviously, there is a tradeoff between energy consumption minimization and UE connection maximization. However, existing works mostly focused on designing energy saving schemes for access networks but little can be found taking UE connection constraints into account. Toward this end, we provide this paper to explore the problem of minimizing energy consumption with UE connection constraints, where a constrained optimization problem is formulated and three solutions are presented, i.e., a brute force algorithm, a heuristic greedy algorithm, and a snowball rolling algorithm. Numerical results reveal that the heuristic greedy and snowball rolling algorithms have much higher computational efficiency than the brute force method, and can also achieve near-optimal solutions for the problem of minimizing energy consumption with UE connection constraints in FiWi enhanced LTE-A HetNets.