Abstract: Aimed at the shortcomings that the total energy efficiency and capacity of the system can not be
considered at the same time of the classical resource allocation scheme, subcarrier average power allocation
scheme and power allocation scheme based on maximum communication capacity and maximum system energy
efficiency in SCMA( Sparse Code Multiple Access) downlink system, a hybrid SCMA power allocation scheme
based on scale factor control in downlink is proposed. The capacity and energy consumption of the system are
optimized as the main direction, and the system could flexibly adjust the tendency by inserting the scale factor.
Since the problem is a nonconvex optimization problem, it is first transformed into a convex optimization problem
by GDA (Generalized Dinkelbach's Algorithm), and then the reasonable Lagrange value is selected to iteratively
solve the model by used KKT (Karush-Kuhn-Tucker) conditions. Finally, the energy efficiency and capacity of
the system are optimized by adjusted the scale factor. The theoretical analysis and simulation results show that
the proposed hybrid law allocation scheme can effectively improve the downlink system capacity and energy
efficiency compared with the traditional scheme.

Key words: sparse code multiple access (SCMA);  , resource allocation;  , power distribution;  , scale factor