Performance of IDMA-Based NOMA with NR-Based Realistic Channel Estimation

Non-orthogonal multiple access (NOMA) is among new features considered for the fifth generation (5G) of mobile communications systems, also known as New Radio (NR). Schemes based on low code rate implementation, such as interleave division multiple access (IDMA) are among the candidate schemes for NOMA transmission in NR. It has been shown that NOMA schemes based on low code rate implementation are poised to offer a robust performance in highly interfered scenarios. However, since in most studies, an ideal channel estimation has been assumed, the sensitivity of the multiplexing performance to channel estimation errors has not been widely investigated. In this paper, we present our performance evaluation results of an IDMA-based transmission with imperfect channel estimation. The channel estimation is based on the recently designed NR R-15 demodulation reference signal (DMRS). In our evaluation, we consider various overloading, interference scenarios and channel estimation assumptions to demonstrate the multiplexing capability of IDMA. Also, we investigate the performance of an error model for channel estimation to show its accuracy and reliability for NOMA evaluation scenarios with more than 12 users, which is not supported by the current R-15 DMRS design.