CSI-based Sensing with NOMA of Multiple Sensing Users for ISAC

As wireless technology continues to evolve, the integration of sensing and communication layers is becoming increasingly necessary. However, this integration presents significant technical and commercial challenges. The main challenges are the issues of coexistence, scheduling, and interference which arise due to the increase in the number of signals transmitted over networks. Transmitting signals orthogonally may not be spectrally efficient, hence the need for non-orthogonal multiple access (NOMA) technology is increasing in the future wireless technology. This paper proposes the use of integrated sensing and communication (ISAC) with iterative channel estimation (ICE) to overlap sensing and communication signals, for multiple sensing users (SUs). To assess the effectiveness of this approach, we compared the bit error rate (BER), mean square error (MSE), and spectral efficiency of sending both sensing users (SUs) and communication users (CUs) using non-orthogonal and orthogonal techniques.