Simple round-trip delay and channel-aware scheduler in wireless communications for feedback control applications

This paper investigates a round-trip delay (RTD) and channel-aware scheduler in wireless communications for feedback control applications. We propose a simple uplink (UL) and downlink (DL) scheduling method that achieves high spectrum efficiency while preventing the RTD from exceeding the allowable maximum delay as much as possible. The proposed method derives the scheduling metric for round-trip communication to minimize the appropriately defined risk of transmission failure based on the expected delay time of candidate terminals. The proposed method is simple and realistic since it reduces the number of parameters to be carefully tuned compared to the conventional α-proportional fair round-trip multiple deadlines (AP-RMD) method. Computer simulation results reveal that the proposed method accommodates more terminals while guaranteeing the maximum allowable RTD under a limited system bandwidth with fewer parameter adjustments than conventional methods, including AP-RMD.