5G new radio (NR) technology is introduced to satisfy more demanding services. Ultra-Reliable Low Latency Communication (URLLC) requires very low delay compared with the previous techniques. This is hard to achieve when hybrid automatic repeat request (HARQ) is applied and especially when the feedback channel is erroneous. In this work, we consider various delay components in incremental redundancy (IR) HARQ systems and minimize the average delay by applying asymmetric feedback detection (AFD) and find the optimal transmission length for each transmission attempt. A M/G/1 queuing model is used in this work to analyze the queuing delay in 5G NR when there are multiple uses in the system. Numerical results show that significant performance gains and lower outage probability can be achieved by applying AFD.

翻译：5G新无线电（NR）技术被引入以满足更高要求的业务需求。与以往技术相比，超可靠低延迟通信（URLLC）要求极低的时延。当采用混合自动重传请求（HARQ）时，特别是反馈信道存在错误的情况下，这一目标是难以实现的。本文研究了增量冗余（IR）HARQ系统中的各类时延分量，通过应用非对称反馈检测（AFD）来最小化平均时延，并为每次传输尝试确定最优传输长度。本文采用M/G/1排队模型来分析系统中存在多个用户时5G NR的排队时延。数值结果表明，应用AFD能够实现显著的性能增益并降低中断概率。