Contrary to orthogonal multiple-access (OMA), non-orthogonal multiple-access (NOMA) schemes can serve a pool of users without exploiting the scarce frequency or time domain resources. This is useful in meeting the sixth generation (6G) network requirements, such as, low latency, massive connectivity, users fairness, and high spectral efficiency. On the other hand, content caching restricts duplicate data transmission by storing popular contents in advance at the network edge which reduces 6G data traffic. In this survey, we focus on cache-aided NOMA-based wireless networks which can reap the benefits of both cache and NOMA; switching to NOMA from OMA enables cache-aided networks to push additional files to content servers in parallel and improve the cache hit probability. Beginning with fundamentals of cache-aided NOMA technology, we summarize the performance goals of cache-aided NOMA systems, present the associated design challenges, and categorize related recent literature based on their application verticals. Concomitant standardization activities and open research challenges are highlighted as well.

翻译：与正交多址接入相比，非正交多址接入方案无需占用稀缺的频域或时域资源即可服务大量用户，这对于满足第六代网络低延迟、海量连接、用户公平性和高频谱效率等需求至关重要。另一方面，内容缓存通过预先在网络边缘存储热门内容来限制重复数据传输，从而降低6G数据流量。在本综述中，我们重点研究基于缓存辅助NOMA的无线网络，这类网络能够同时利用缓存和NOMA的优势——从OMA切换到NOMA使缓存辅助网络能够并行向内容服务器推送更多文件，并提升缓存命中概率。我们从缓存辅助NOMA技术的基本原理出发，总结其系统性能目标，提出相关设计挑战，并根据应用场景对近期相关文献进行分类。同时，本文还重点介绍了相应的标准化活动及未解决的开放性研究挑战。