An intelligent optimization algorithm for joint MCS and resource block allocation in LTE femtocell downlink with QoS guarantees

In this paper, we address the problem of joint Resource Block (RB) allocation and Modulation-and-Coding Scheme (MCS) selection for LTE femtocell DownLink (DL). We first formulate the problem as an Integer Linear Program (ILP) whose objective is to minimize the number of allocated RBs of a closed femtocell, while guaranteeing minimum throughput for each user. In view of the NP-hardness of the ILP, we then propose an intelligent optimization algorithm called ACO- HM algorithm with reduced polynomial time complexity. In the ACO-HM algorithm, the Ant Colony Optimization (ACO) algorithm is to allocate appropriate RBs to mobile users, while the Harmonic Mean (HM) method is to select a better MCS than the MINimum/MAXimum MCS selection schemes (MINIMAX). Simulation results show that compared with the ACO-MIN algorithm and the ACO-MAX algorithm, the proposed ACO- HM algorithm achieves better performance with fewer RBs and provides Quality-of-Service (QoS) guarantees.