Performance Improvement of Non-orthogonal Multiple Access scheme using Code Division Multiplexing

Currently, the standardization of fifth generation mobile communication system (5G), which realizes 10 Gbps transmission, is in progress. In mobile communications, it is generally difficult to perform high-capacity transmission because of channel fading. Therefore, an adaptive resource allocation scheme based on users' channel conditions is adopted to enhance the system capacity. Recently, it has been shown that a nonorthogonal multiple access (NOMA) scheme can achieve a higher system capacity than orthogonal multiple access scheme. However, anticipating a continuous increase of mobile traffic, it is desired to further enhance the capacity of NOMA scheme. Therefore, we propose an application of code division multiplexing to NOMA scheme using successive interference canceller to improve the throughput performance. The improved performance is demonstrated through numerical simulations.