Conflict and Trade-off of Waveform Uncertainty in Joint Communication and Sensing Systems

In joint communications and sensing (JCS), the two functions are integrated into the same waveform and hardware, which substantially reduces the consumptions of bandwidth and power. However, there exist conflicts of interests between communications and sensing, when they share the same resource. One major conflict is the uncertainty of waveform that is necessary to communications but harmful for sensing. In this paper, the conflict and trade-off in the waveform uncertainty are analyzed for orthogonal frequency division multiplexing (OFDM) waveforms and wide sense stationary (WSS) waveforms, in terms of data transmission rate of communications and integrated sidelobe level (ISL) for sensing. It is shown by numerical results that high-order quadrature amplitude modulation (QAM) results in higher ISL (thus lower capability of target identification), while a single-sided Gaussian-distributed power spectral density (PSD) in WSS waveforms achieves the optimal trade-off in the waveform uncertainty.