A Study of Parallel Interference Cancellation Combined with Successive Interference Cancellation for UL-NOMA Systems

As Internet of Things (IoT) develops, new radio access techniques that can effectively accommodate a massive number of devices transmitting small-size data are required to improve frequency utilization efficiency. We have researched and developed a system that can realize massive connections using non-orthogonal multiple access (NOMA). For NOMA systems, we have prepared successive interference cancellation (SIC) and parallel interference cancellation (PIC) to separate superimposed signals. However, PIC has a huge amount of calculation while SIC requires a certain amount of power difference to separate superimposed signals. Hence, in order to mitigate the disadvantage of PIC, we propose the method in which PIC is performed after SIC for NOMA systems. By combining SIC and PIC, the amount of calculation can be reduced with little deterioration from PIC performance. By computer simulation, we evaluate packet error rate (PER) and the amount of calculation. From the results of the simulation, we confirm that the proposed method is effective to reduce the amount of calculation by about 1/10.