  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.
