A Cognitive Radio Relay Selection Scheme in Two-Tier Femtocell Networks

The effective cross-tier interference (CTI) mitigation is a key technique for the macrocell and femtocell two-tier heterogeneous networks. In this paper, a cognitive radio relay selection (CRRS) scheme is proposed to improve the quality of service (QoS) of the femto-networks. On the one hand, for the macro-network, the scheme is intended to ensure the macrocell users can endure much more interference from the femtocell users. On the other hand, with respect to the femto-networks, the scheme can effectively improve the received signal strength relative to cross-tier macrocell interference of the femtocell users. As a result, the femtocell users can obtain a relative improvement in their Signal-to-Interference-plus-Noise-Ratio (SINR). Simulation results demonstrate that, compared with the existing works, the proposed scheme can not only increase the number of the successful femtocell users, but also improve the average SINR of the femtocell users.