Power Minimization Precoding in Uplink Multi-Antenna NOMA Systems

Abstract-By exploiting the power domain, non-orthogonal multiple access (NOMA) is capable of improving system spectrum efficiency and supporting massive concurrent connections. However, NOMA transmissions are susceptible to jamming attacks. In this paper, we study anti-jamming policies in a NOMA system by using the multiple-input-multiple-output (MIMO) technique. A novel anti-jamming precoding design is proposed for minimizing the total transmit power of an uplink MIMO-NOMA system. In the proposed scheme, transmitters are divided into multiple groups. Precoders at the transmitters in the same group and equalizers at the receiver are jointly designed to enhance system power efficiency, while successive interference cancellation is employed to eliminate inter-group interference. Two sequential algorithms with closed-form procedures are developed to compute the precoding matrices. Simulation results show that the proposed NOMA scheme outperforms the existing signal alignment NOMA scheme and its orthogonal multiple access (OMA) counterpart in terms of the total power consumption. Besides, the proposed NOMA scheme can perform very well even when only the sample covariance matrix of jamming interference is available.