Injection Optimization for Uniform QAM-Based Non-Orthogonal Multiplexing Systems

Non-orthogonal multiplexing (NOM) is a promising technique for wireless broadcasting which provides versatile broadcasting services to mobile and fixed users simultaneously. For an NOM system, injection optimization among signals in multiple layers is an important problem. In this paper, considering a uniform quadrature amplitude modulation-based NOM system, we propose to solve the injection optimization problem which minimizes the sum bit-error-rate (BER). To solve the problem, we theoretically derive the BER expressions of users in different subgroups, e.g., the subgroup of mobile users and that of fixed users in ATSC 3.0 standard. With the obtained BER expressions, a near optimal solution utilizing the logarithmic barrier method is proposed. It is shown through simulation results that among different injection level values, our proposed injection scheme achieves the lowest sum BER.