Information- Theoretic Limits of Integrated Sensing and Communication over Interference Channels

Integrated sensing and communication (ISAC) emerges as a critical technology for future 6G cellular networks. The distinct nature of sensing-centric and communication-centric waveforms poses a challenge, as a unified design can lead to a performance tradeoff between sensing and communication. Most of the previous studies focused on single ISAC base station (BS) scenarios and explored capacity-distortion tradeoffs for various ISAC channels. However, practical scenarios involve multiple ISAC BSs in the same region, sharing time-frequency resources and causing interference, which impacts both sensing and communication functions. To address this challenge, we propose an information-theoretic modeling of monostatic ISAC over interference channels. In the model, two interfering ISAC BSs seek to communicate with their users while performing sensing estimation through received echo signals. An achievable scheme is developed for the considered model, utilizing superposition coding and joint compression of past transmitted codewords and echo signals via distributed Wyner-Ziv coding. The corresponding achievable rate-distortion region is characterized, and a specific example is provided to demonstrate the advantages of the proposed scheme. Our results highlight that interference links, in conjunction with echo signals, can be strategically leveraged to achieve unified cooperative sensing and communication between the two BS-user pairs.