Energy-spectral efficiency tradeoff for heterogeneous networks with QoS constraints

In this paper, we investigate the energy efficiency (EE) and spectral efficiency (SE) tradeoff in multi-cell heterogeneous networks (HetNets). Our objective is to maximize both EE and SE of the network while satisfying the rate requirement of users. We use multi-objective optimization techniques to define the objective function. We propose a three-stage algorithm in this paper. First, we select the cell-center radius for the fractional frequency reuse (FFR) method. Second, we assign the frequency resources to satisfy the rate requirements of users and maximize the objective function. Third, the power allocation subproblem is solved by using the Levenberg-Marquardt method. Our numerical results show that a Pareto-optimal solution exists for EE and SE. We present results for different rate constraints.