CORDIS: A Scalable Coordinated Resource Allocation Framework for Distributed Cell-Free ISAC

Abstract

Integrated Sensing and Communication (ISAC) is envisioned as a key technology for 6G wireless networks, enabling the joint use of spectrum and hardware for sensing and communication. In multi-static cell-free architectures, coordinating beamforming and power resources across distributed access points (APs) is critical in order to mitigate severe communication-sensing interference. Most existing ISAC resource allocation solutions rely on centralized architectures with full network knowledge, which limits their scalability and practicality in distributed cell-free deployments with imperfect channel state information (CSI). In this paper, we introduce a framework for COordinated Resource allocation for Distributed ISAC Systems (CORDIS) that optimizes network sensing while suppressing clutter and maintaining per-user communication performance constraints. Two algorithms are developed: CORDIS-Split, a low-overhead scheme that pairs fixed local beamformers with centralized power allocation, and CORDIS-ADMM, which jointly optimizes beamforming and power through the consensus Alternating Direction Method of Multipliers (ADMM). By localizing high-dimensional matrix operations, both algorithms ensure fronthaul overhead and per-AP computation remain independent of antenna and AP counts. Simulations demonstrate that CORDIS-ADMM approaches the centralized performance bound and degrades gracefully under CSI estimation error, remaining effective even with locally rank-deficient channels, while CORDIS-Split offers a minimal-overhead alternative. These results confirm that CORDIS is a scalable and communication-efficient foundation for robust ISAC in decentralized wireless networks.