Network-Assisted Full-Duplex Enabled Ultrareliable and Low-Latency Communications

Abstract

The ultrareliable and low-latency communication (URLLC) is one of the key scenarios of the current 5G new radio (NR). The performance of the duplex technologies in URLLC to assist in meeting the needs of low-latency services is of great significance. However, time division duplex (TDD) has poor delay performance due to the extra data waiting delay caused by the frequent uplink/downlink switching. Besides, TDD systems cannot dynamically adapt to the real-time changes of user requirements due to the problem of frame structure configuration, while frequency division duplex (FDD) has more pilot overhead due to channel estimation and worse spectrum utilization which are great drawbacks in 5G NR enabled URLLC. In this paper, we further proposed the strengths of a novel duplex technology named network-assisted full-duplex (NAFD) in terms of URLLC latency performance compared with TDD and FDD. NAFD scheme exploits the resources of the time and spatial domains to form a special duplex mechanism where the central processing unit (CPU) can dynamically assign the modes of different access points (APs) as downlink transmission or uplink receiving in the same coherent time block. Some improvement of the existing NAFD scheme for better fitting for URLLC is also proposed in this paper. The simulation results and analysis showed that the NAFD scheme outperforms other duplex technologies under URLLC scenarios.