Unlicensed Assisted Ultra-Reliable and Low-Latency Transmission

The ultra-reliable and low-latency communication (URLLC) has many potential applications in the Internet of Things (IoTs). This paper exploits both the licensed and unlicensed spectrums to support the URLLC transmissions, alleviating the lack of licensed spectrum resources, and adopts the duty-cycle muting (DCM) to ensure fair coexistence with the WiFi network. The user grouping scheme, mini-slot frame structure, and finite block length regime are used to guarantee low latency and high reliability. Meanwhile, to reduce the power consumption at the URLLC devices, we establish a minimum power optimization model and provide the globally optimal solutions. Simulation results are presented to verify the feasibility and effectiveness of the proposed scheme, which can not only reduce the power consumption at the devices, but also improve the system spectrum efficiency.