Many-to-Many Matching User Association Scheme in Ultra-Dense Millimeter-wave Networks

Millimeter-wave (mmWave) communication has been regarded as one of the most promising means to improve system throughput in the fifth-generation (5G) era. However, there exists signal blockage problem in mmWave network. We consider the combination of mmWave communication with ultradense network (UDN) and virtual cell structure. UDN allows multiple small base stations (SBSs) to be deployed within a limited area. user-centric virtual cell structure enables users to associate multiple mmWave SBSs simultaneously by using coordinated multi-point (CoMP) transmission technology. Therefore, we formulate user association problem for ultra-dense mmWave networks to maximize system throughput while guaranteeing quality of service (QoS) requirements of users. To solve this nonlinear binary integer programming optimization problem, a novel user association scheme based on the many - to-many two-sided matching game with externalities is proposed. To characterize the properties of proposed scheme, we prove that it converges to the two-sided exchange stability within a limited number of iterations. Simulation results show that proposed scheme significantly outperforms other schemes in improving user rate and system throughput while guaranteeing QoS requirements of users.