A Tree Topology Power Allocation Algorithm for Non-Orthogonal Multiple Access System in 5G System

Due to its superior spectral efficiency and higher system capacity, non-orthogonal multiple access (NOMA) has recently become a promising candidate scheme in 5G systems. In this paper, we discussed the basic theory of NOMA system first of all. Then, we studied the systems capacity optimization problem of NOMA system under the constraints of total transmit power and the minimum rate of the weaker user. Then a tree topology power allocation algorithm is discussed, which achieves the same performance as the FSPA method. but its computation complexity decreases from exponential to constant. The results of numerical simulation showed proposed algorithm has lower computational complexity and can realize higher system capacity. Meanwhile, higher system capacity can be achieved through adjusting the power allocation factor a in FPA algorithm.