Joint User Association and Power Allocation for Max-Min Fairness in Downlink Multicell NOMA Networks

This paper investigates an optimization problem of the joint user association and power allocation for max-min fairness in downlink multicell non-orthogonal multiple access (NOMA) networks. In order to solve this optimization problem, we first decouple it into user association and power allocation subproblems. Then, three user-association criteria are proposed to realize tradeoffs of complexity and throughput of the worst user. Furthermore, under given user association case, a decentralized strategy, namely, diffusion adaptive power allocation is proposed to achieve overall network fairness, in which each base station (BS) optimizes local fairness with little exchanged information of average user performance of its neighbors. In addition, we study a low-complexity adaptive PA algorithm to implement the proposed strategy. Numerical results show that the proposed algorithms can achieve a better performance compared with exsiting schemes.