ICT Convergence Research Center, Kumoh National Institute of Technology, Gumi 39177, Gyeongbuk, Korea.
Department of IT Convergence Engineering, Kumoh National Institute of Technology, Gumi 39177, Gyeongbuk, Korea.
Sensors (Basel). 2021 Oct 24;21(21):7052. doi: 10.3390/s21217052.
Non-orthogonal multiple access (NOMA) has a key feature that the cell-center user (CCU) has prior information about the messages of the cell-edge user (CEU) in the same user-pair. It means that CCU can be used for retransmission when the CEU requests retransmission. As ultra-reliability and low-latency communication (URLLC) requires high-reliability constraints (e.g., 99.999%), using CCU for retransmission can be useful to satisfy the reliability constraint. In this study, to ensure the reliability of CEU, cooperative retransmission (CR) scheme for downlink NOMA systems is proposed. And the CR scheme is evaluated with Block error rate (BLER) considering reliability and with packet loss rate (PLR) in terms of reliability and latency constraints. And the evaluation results showed that the proposed CR scheme can satisfy the target BLER for URLLC low SNR compared to the conventional retransmission scheme, and showed the improved PLR compared to the conventional retransmission scheme in low SNRs.
非正交多址接入（NOMA）具有一个关键特性，即在相同用户对中，小区中心用户（CCU）具有关于小区边缘用户（CEU）消息的先验信息。这意味着当 CEU 请求重传时，CCU 可以用于重传。由于超可靠低延迟通信（URLLC）需要高可靠性约束（例如，99.999%），因此使用 CCU 进行重传可以满足可靠性约束。在这项研究中，为了确保 CEU 的可靠性，提出了一种用于下行链路 NOMA 系统的协作重传（CR）方案。并通过考虑可靠性的块错误率（BLER）和考虑可靠性和延迟约束的分组丢失率（PLR）来评估 CR 方案。评估结果表明，与传统重传方案相比，所提出的 CR 方案在 URLLC 低 SNR 下可以满足目标 BLER，并且在低 SNR 下与传统重传方案相比显示出改善的 PLR。
