Joint rate adaptation and user scheduling in HARQ-based multi-user systems with heterogeneous mobility

In this paper, we study a joint rate adaptation and user scheduling problem in HARQ-based multi-user systems. We first investigate a tradeoff between the rate selection and user selection through two extreme scheduling criteria: retransmission oriented scheduling (ROS) and mixed scheduling (MS) criteria. Then, we propose a baseline procedure for the joint rate adaptation and user scheduling (JRAUS). Based on the baseline procedure, we introduce a conventional MS-based JRAUS policy, our proposed ROS-based JRAUS policy, and reference JRAUS policies. Finally, through system-level simulations, we evaluate the system performance of the proposed ROS-based JRAUS policy, compared with the conventional and reference JRAUS policies, in homogeneous and heterogeneous mobility scenarios. Through this study, we find that the rate adaptation is not only important in a single point-to-point link but also is very significant in HARQ-based multi-user systems with heterogeneous mobility. Moreover, the rate adaptation needs to be more carefully considered than the user scheduling in heterogeneous mobility scenarios.