An optimum power allocation scheme for non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC) technique for downlink channels of next generation cellular networks is proposed in this paper. In NOMA downlinks, the signals for each user are superimposed at the transmitter side and SIC is implemented at the receiver side to separate them. Numerical results show that the overall system throughput performance can be improved significantly by the proposed power allocation algorithm with NOMA in comparison with orthogonal multiple access (OMA), which is implemented in previous wireless telephone technology generations.

In this paper, non-orthogonal multiple access (NOMA) with successive interference cancellation (SIC) technique for downlink channel of next generation wireless network and its security issues are discussed. In NOMA, signals for all user equipment (UEs) are superimposed before transmission and then decoded at each UE implementing SIC. SIC relies on decoding and subtracting the signals in sequence until it reaches its desired signal. The decoding order at each UE, however, must match with the user index in the cancellation sequence. In case of mismatch, UEs will not obtain their signals and re-request their messages from the BS which will further increase the processing time that is already high for a regular SIC receiver. Numerical results show the performance of SIC at the UE side. The time spent for decoding the received signal at the UE with and without user mismatch is discussed. The unusual longer decoding times are further discussed as potential external network threat.

Non-orthogonal multiple access (NOMA) is a promising method for the fifth generation (5G) cellular networks as it provides improved spectral efficiency by multiplexing users in power domain. One key challenge for the receivers in NOMA networks is to distinguish the individual signals that use the same band at the same time. Currently, the two widely discussed decoding schemes are successive interference cancellation (SIC) and parallel interference cancellation (PIC). Both schemes suppress the multi-user interference by subtracting the decoded signals from the received signal based on different algorithms, i.e., SIC decodes iteratively and PIC decodes collectively. This paper compares the computation time of SIC and PIC schemes at the base station and demonstrates multi-thread implementation of PIC.

Non-orthogonal multiple access (NOMA) is a candidate multiple access scheme for the fifth-generation (5G) cellular networks. In NOMA systems, all users operate at the same frequency and time, which poses a challenge in the decoding process at the receiver side. In this work, the two most popular receiver structures, successive interference cancellation (SIC) and parallel interference cancellation (PIC) receivers, for NOMA reverse channel are implemented on a graphics processing unit (GPU) and compared. Orthogonal frequency division multiplexing (OFDM) is considered. The high computational complexity of interference cancellation receivers undermines the potential deployment of NOMA systems. GPU acceleration, however, challenges this weakness, and our numerical results show speedups of about from 75–220-times as compared to a multi-thread implementation on a central processing unit (CPU). SIC and PIC multi-thread execution time on different platforms reveals the potential of GPU in wireless communications. Furthermore, the successful decoding rates of the SIC and PIC are evaluated and compared in terms of bit error rate.