标题： 灵活的多址接入技术实现低时延通信：引入NOMA-R 显示英文标题

标题： Flexible Multiple Access Enabling Low-Latency Communications: Introducing NOMA-R

摘要： 在5G及更高级（B5G）网络的各个垂直领域中，需要非常严格的延迟保证，同时又设想了大规模连接。因此，选择最优的多址接入（MA）技术以实现低延迟是B5G的关键使能技术。特别是，由于潜在的高碰撞数量，上行传输中的这一问题更为突出。在此基础上，本文讨论了使用优化MA技术的延迟敏感上行连接问题；为此，我们对各种MA方法相对于可实现的有效容量（EC）进行了比较分析。与标准速率（物理层）或吞吐量（媒体访问控制层）分析不同，我们提出了有效容量的概念，作为一种适合表征物理层-媒体访问控制层延迟的度量指标。研究的MA方法包括上行场景中的标准正交MA（OMA）和功率域非正交MA（NOMA），同时考虑随机配对和优化配对方案。它进一步扩展到包含一种最近提出的第三种替代方案，称为NOMA相关（NOMA-R），该方案通过灵活选择MA技术来扩展OMA和NOMA方法。我们表明，优化用户配对和MA选择可以增加网络有效容量，尤其是在有严格延迟约束的情况下；因此，灵活的MA是一种未来低延迟应用的潜在优选策略。 显示英文摘要

摘要： Various verticals in 5G and beyond (B5G) networks require very stringent latency guarantees, while at the same time envisioning massive connectivity. As a result, choosing the optimal multiple access (MA) technique to achieve low latency is a key enabler of B5G. In particular, this issue is more acute in uplink transmissions due to the potentially high number of collisions. On this premise, in the present contribution we discuss the issue of delay-sensitive uplink connectivity using optimized MA techniques; to this end, we perform a comparative analysis of various MA approaches with respect to the achievable effective capacity (EC). As opposed to standard rate (PHY) or throughput (MAC) analyses, we propose the concept of the effective capacity as a suitable metric for characterizing jointly PHY-MAC layer delays. The palette of investigated MA approaches includes standard orthogonal MA (OMA) and power domain non orthogonal MA (NOMA) in uplink scenarios, both considering random pairing and optimized pairing alternatives. It further extends to encompass a recently proposed third alternative, referred to as NOMA-Relevant (NOMA-R), which extends OMA and NOMA approaches by flexibly selecting the MA technique. We show that optimizing both user pairing and MA selection increases the network EC, especially when stringent delay constraints are in place; thus a flexible MA is a potentially preferable strategy for future low latency applications