Fair Optimal Power Allocation for Non-orthogonal Multiple Access Heterogeneous Networks

In wireless communication transmission system, it is difficult to obtain the perfect channel state information (CSI) due to the stochastic channel condition and link delay, but most of studies for non-orthogonal multiple access (NOMA) heterogeneous networks always assume that the base station (BS) has perfect CSI. Therefore, in this paper, we study the energy efficient power allocation with a full consideration of users fairness for the NOMA heterogeneous networks based on the imperfect CSI. The probabilistic optimization problem with outage probability is transformed to a non-probabilistic problem via the approximation of inequality. The binary search method is designed to solve the power allocation problem of small cells. The simulation results show that the proposed algorithm with different parameters can greatly improve the energy efficiency of the system.