Opportunistic Device Association for Heterogeneous Cellular Networks With H2H/IoT Co-Existence Under QoS Guarantee

The integration of Internet of Things (IoT) and heterogeneous cellular networks (HCNs) forms a promising paradigm for next generation mobile systems. In this paper, a new association algorithm with quality of service provisioning is proposed to consider the diverse association requirements for human-to-human (H2H) communications and IoT devices (IoTDs) coexisted in HCN. In this context, the devices are categorized into two main classes; rate oriented devices (RODVs) and power oriented devices (PODVs). RODVs are primarily used to model H2H devices while PODVs are mainly used to model IoTDs during the association process. Then, the device association is formulated as an adaptive optimization problem that considers DL rate only, UL transmit power only or both of them according to devices orientations. Since the formulated optimization problem is hard to solve due to the combinatorial device association indicators, we reformulate the proposed optimization problem into a better tractable problem by relaxing the combinatorial indicators. Then, Lagrange dual decomposition method is adopted to find the optimal solution. Moreover, a radio channel distribution mechanism is proposed as a subsequent step to the device association phase for RODVs where the remaining resources after device association phase are distributed among the RODVs. Simulation results show that our proposed algorithm outperforms the comparable schemes especially in terms of power distribution for PODVs and rate distribution for RODVs with a significant rate gain.