Sensing-Communication Coexistence vs. Integration

The design options of sensing-communication coexistence (SCC) vs. integrated sensing and communications (ISAC) relying on non-orthogonal downlink transmission (NO-DLT) and transmit antenna selection are investigated. To be practical, both realistic residual hardware impairments (RHI) and imperfect successive interference cancellation are considered. The performance of the SCC and ISAC NO-DLT frameworks is characterized by deriving both the exact and the asymptotic outage probabilities (OPs) as well as the probability of successful target detection (PoD). Our numerical results demonstrate the accuracy of the theoretical analysis and confirm that: 1) The ISAC NO-DLT framework is superior to the SCC NO-DLT framework both in terms of its OP and PoD; 2) The realistic RHI degrades the S&C performance of both the SCC and ISAC NO-DLT frameworks.