## 1 Introduction
### Resource Allocation Issue for the NOMA System
Yet, the implementation of NOMA-MEC connections confronts numerous tactical and technological obstacles. To establish and implement effective and sustainable NOMA-MEC relationships, it is essential to comprehend the present phase of the investigation to recognize the main difficulties and possibilities. This investigation is an SLR that concentrates on the present situation regarding MEC connections enabled by NOMA NOMA-MEC connections are an intriguing innovation capable of meeting the rising need for fast, low-latency, and dependable 6G mobile communication systems. Therefore, the primary objective of this SLR on NOMA-enabled MEC connections is to present an in-depth knowledge of existing present-day studies conducted in this field of study. This SLR aims to recognize NOMA-MEC connection gaps in analysis, advantages, and limitations in the current body of research. The study specifically addresses this issue by examining and responding to the following research questions in the areas that are underlined:  
1. What strategies, methods, and approaches have scholars recommended to enhance the operational efficiency of NOMA-MEC connections? 2. What are the gaps in knowledge, advantages, and limitations regarding NOMA-MEC connections in the published literature? 3. What are the primary obstacles and possibilities associated with creating and implementing NOMA-MEC in 6G connections? 4. What are the prospective areas of investigation for creating and implementing NOMA-MEC connections that are economical and sustainable? In summary, this survey aims to deliver a thorough knowledge of the present state of study on NOMA-MEC in 6G connections and to recognize the difficulties and possibilities associated with the potential creation and implementation of effective and sustainable mobile communication systems. To address the RQs mentioned above, the SLR is conducted using a standardized and thorough PRISMA approach (Supplementary Materials). The procedure involves establishing the RQs, undertaking a planned search for pertinent literature, evaluating and choosing the research articles according to established inclusion and exclusion requirements, and then assessing the selected studies employing an established collection of data method. Scientists, entrepreneurs, and governments concerned with creating and implementing effective and sustainable 6G mobile communication structures can benefit from the findings of this investigation. NOMA-MEC in 6G communications can contribute in the following ways to sustainability. 1. NOMA-MEC provides cost-effective and adaptable resource distribution in 6G networks, facilitating many users' concurrent utilization of the same resources. This leads to a greater effective application of resources and may lower energy consumption, contributing to sustainability. 2. NOMA-MEC may encourage the implementation of edge computing, which allows the consideration of data closer to its origination. This may minimize the quantity of data that must be conveyed over vast distances, thereby reducing energy consumption and carbon emissions related to the transfer of information. 3. NOMA-MEC can aid in the establishment of intelligent and environmentally friendly communities. NOMA-MEC may facilitate the creation of applications such as smart transportation, smart energy management, and smart waste management that enhance the sustainability of communities by promoting the effective utilization of resources and peripheral computing. 4. NOMA-MEC in 6G connectivity can help achieve sustainability by promoting effective resource utilisation, minimizing energy consumption, promoting periphery computing, and aiding the establishment of intelligent and sustainable cities. The rest of this paper is pre-structured; thus, Section 2 discusses the literature relating to the study. The resources and procedures employed for this survey are discussed in Section 3. Section 4 presents the findings and discussion, including answering the research questions formulated earlier in the study.