论文标题
分析URLLC服务的无赠款访问
Analyzing Grant-Free Access for URLLC Service
论文作者
论文摘要
5G新无线电（NR）有望支持新的超级可靠的低延迟通信（URLLC）服务，以支持具有非常严格的延迟和可靠性要求的小数据包传输。当前的长期演化（LTE）系统是基于基于授予的（GB）（即动态授予）随机访问设计的，这几乎不能支持URLLC要求。提出了免费赠款（GF）（即配置的授予）访问权限，作为一种可行且有希望的技术来满足此类要求，尤其是对于上行链路传输，这有效地节省了请求/等待赠款的时间。尽管在NR Release 15中提出了一些基本的GF访问功能和标准化，但仍有很多改进的空间。在本文中分析了三个带有混合自动重复请求（HARQ）重复请求（包括反应性，K-重复和主动性）的混合自动重复请求（HARQ）重复请求（HARQ）的GF访问方案的3GP研究项目。具体而言，我们为基于竞争的GF访问分析提供了时空分析框架。基于此框架，我们定义了表征URLLC可靠性和延迟性能的潜在访问失败概率。我们提出了一种可拖动的方法，以在三种GF HARQ方案下得出和分析典型UE的潜在访问失效概率。我们的结果表明，在较短的延迟限制下，主动方案提供了最低的潜在访问失效概率，而在较长的延迟约束下，K重复方案实现了最低的潜在访问失效概率，这取决于K。
5G New Radio (NR) is expected to support new ultra-reliable low-latency communication (URLLC) service targeting at supporting the small packets transmissions with very stringent latency and reliability requirements. Current Long Term Evolution (LTE) system has been designed based on grantbased (GB) (i.e., dynamic grant) random access, which can hardly support the URLLC requirements. Grant-free (GF) (i.e., configured grant) access is proposed as a feasible and promising technology to meet such requirements, especially for uplink transmissions, which effectively saves the time of requesting/waiting for a grant. While some basic GF access features have been proposed and standardized in NR Release-15, there is still much space to improve. Being proposed as 3GPP study items, three GF access schemes with Hybrid Automatic Repeat reQuest (HARQ) retransmissions including Reactive, K-repetition, and Proactive, are analyzed in this paper. Specifically, we present a spatiotemporal analytical framework for the contention-based GF access analysis. Based on this framework, we define the latent access failure probability to characterize URLLC reliability and latency performances. We propose a tractable approach to derive and analyze the latent access failure probability of the typical UE under three GF HARQ schemes. Our results show that under shorter latency constraints, the Proactive scheme provides the lowest latent access failure probability, whereas, under longer latency constraints, the K-repetition scheme achieves the lowest latent access failure probability, which depends on K. If K is overestimated, the Proactive scheme provides lower latent access failure probability than the K-repetition scheme.
