Cross-domain Channel Estimation Based Serial Interference Cancellation in NOMA-OTFS System

This paper proposes a serial interference cancellation (SIC) strategy based on cross-domain (CD) channel estimation, named as CD-SIC, in the non-orthogonal multiple access and orthogonal time frequency space (NOMA-OTFS) system to accomplish accurate channel estimation with low pilot overhead and effectively eliminate the multi-user interference. The channel estimation in the time-frequency domain is first done by the least-squares algorithm, and then transferred into the delay-Doppler domain, where the parameters associated with each channel path can be extracted by an iterative algorithm and further used to acquire more accurate channel estimation. We also combine typical equalization algorithms to evaluate the performance of the CD-SIC strategy. Simulation results show that the proposed CD-SIC scheme with the minimum mean square error (MMSE) equalization attains noteworthy performance improvement and user fairness in the NOMA-OTFS system.