THE SHIN LAB @ KOREA UNIV

Caption: An illustration of non-terrestrial networks (NTN) for 6G. Future radio access networks are expected to support a massive number of users with a diverse set of requirements in terms of delay, throughput, etc. These requirements challenge different aspects of the current cellular networks including the multiple access (MA) methods. A common feature of newly designed MA schemes is the use of non-orthogonal multiple access (NOMA) schemes instead of the conventional orthogonal schemes. NOMA is a potential enabler for the development of beyond 5G wireless networks. Compared to the conventional orthogonal multiple access (OMA) schemes such as TDMA and FDMA, NOMA can scale up the number of served users, increase the spectral efficiency, and improve user-fairness. In particular, NOMA has been suggested as a possibility for data transmission in dense networks with a large number of users requesting for access such that there are not enough orthogonal resources to serve them in a OMA-based fashion. As such, NOMA has been proposed for the 3rd Generation Partnership Project (3GPP) Long Term Evolution–Advanced (LTE–A) standards and is envisioned to be a part of 5G cellular networks. Nonetheless, while single-cell NOMA has drawn significant attention recently, much less attention has been given to multi-cell NOMA. Our research goal is to investigate the potentials and challenges of NOMA in a multi-cell environment and to harvest the benefits of NOMA. Inter-cell interference, particularly at the cell-edge, is by far the main challenge in multi-cell networks. This interference situation becomes worse when NOMA is used, as cell-edge users constantly experience interference from the neighboring cell, whereas in the case of TDMA/FDMA interference is limited to certain time slots o