Novel User Scheduling Algorithms for Carrier Aggregation System in Heterogeneous Network

In this paper, the carrier aggregation (CA) is applied to Heterogeneous Networks (HetNets) consisting of a macro base station (MBS) and low-power pico base stations (PBSs). The PBSs are distributed in the outer space of the disk centered at the MBS and the closed-form solution of the radius of the disk is analyzed. In the CA based HetNet, firstly, a practical user association scheme is proposed to classify the users into macrocell user (MUs) and pico-cell users (PUs). Secondly, a PU-centric cooperative transmission strategy is proposed to increase the data rate of PUs. Then, in order to eliminate the cross-tier interference in HetNet, the MUs and PUs schedule different component carriers (CCs) according to different algorithms. For the MUs, an improved simulated annealing (SA) scheduling algorithm is proposed to maximize the sum rate of the MUs. Compared with the existing SA, the inner loop of the proposed SA is redesigned. Consequently, the best value can be obtained more quickly. For PUs, a location information based low-complexity maximize minimum distance (MMD) algorithm is proposed to reduce the interference from PBSs to PUs as much as possible. Overall, an integrated scheme is proposed to improve the performance. At last, numerical results demonstrate the performance of the proposed schemes.