Dirty Paper Coding for Waveform Synthesis in Integrated Sensing and Communications: A Broadcast Channel Approach

In integrated sensing and communications (ISAC), both functions are tightly integrated using the same spectrum, waveform and hardware. Analogy is identified between ISAC and broadcast channel in communications, since ISAC transmitter broadcasts signals for both communication receivers and sensing, despite the functional overlap between communications and sensing. Although the communication signal can also be used for sensing, the intrinsic randomness of communications impairs the reliability of sensing. Therefore, a dedicated and deterministic sensing waveform is added, in order to improve the sensing performance. To remove the interference of the dedicated sensing waveform to communication receivers, dirty paper coding is employed, which exploits precoding for interference cancellation. Meanwhile, the trade-off between communications and sensing is identified. Numerical results are used to demonstrate the proposed ISAC scheme and the performance trade-off.