A Promising Non-Orthogonal Multiple Access Based Networking Architecture: Motivation, Conception, and Evolution

Since it can offer higher spectral efficiency by granting the served data to share the same spectrum resource synchronously, NOMA is considered as a bright multiple access technique for future wireless networks. Accommodating a large number of users with NOMA mode may easily cause inappropriate power assignment problem and result in performance degradation. As a result, existing NOMA operation unit mainly focuses on the two-user scenario, where a centre user is only paired with an edge user. However, such a user pairing strategy will also introduce an unbalance to their data rate fairness. Hence, it is of great importance to develop an effective structure that facilitates low decoding complexity, high system performance, and reasonable user fairness with NOMA. To this end, this article proposes a novel NOMA operation unit, in which successive interference cancellation can be performed to accommodate an arbitrary number of users by integrating the NOMA technique with the orthogonal resource allocation strategy. The proposed NOMA operation unit can further improve the edge user's achievable rate by incorporating the index modulation technique according to the data service demanded by center users.