Adaptive flexible spectrum usage algorithms in heterogeneous cell deployment

The International Telecommunication Union (ITU) established new requirements for the next generation of wireless communications. To meet those requirements, the concept of femtocells emerged as a solution, aiming at increasing capacity and offloading the macrocell network. In a co-channel deployment between macrocells and femtocells, the interference is a serious problem and that needs to be addressed. Since the femtocells are deployed by the end-user, the operator does not have a pre-planned solution to avoid interference, thus a self-organizing solution between femtocells located in the same area is required to manage the interference. In this paper we propose a flexible spectrum usage algorithm which runs at the femtocells, while the macrocells use a fixed reuse scheme in order to manage the interference in the network. In this study we verify that by assigning a fixed reuse scheme 1/3 for the macrocells, the performance achieved by the users is higher, when comparing the same scenario with reuse 1. We also propose a flexible spectrum usage algorithm for the femto cell, which is able to achieve higher user throughput in the femto layer and minimize the interference in the macro layer, when compared to a non-channel aware algorithm, which allocates the PRBs randomly.