Resource-Efficient Dual Connectivity for Ultra-Reliable Low-Latency Communication

Dual connectivity for reliability is considered one of the most important enablers of ultra-reliable low-latency communication in fifth-generation cellular systems. In this paper, we focus on downlink dual connectivity, proposing two methods that prevent unnecessary duplicates transmissions to enhance spectral efficiency when using data duplication. In the first method, the duplicates of packets already successfully delivered to the terminal are promptly dropped from the transmission queues of the involved base stations thanks to an uplink indication provided by terminal itself. In the second method, the transmission of duplicates from the secondary node is enforced only upon a failure of the master node. The performance of the two proposed schemes is evaluated in terms of i) achievable packet reliability within the 1-ms latency target of ultra-reliable low-latency communication, and ii) resource-block utilization via system-level simulation campaigns. The results show that, in the investigated scenario, the second proposal can support a four-times higher offered load with respect to the baseline approach.