Instruction-Directed MAC for Efficient Classical Communication in Scalable Multi-Chip Quantum Systems

Scalable quantum computing requires modular multi-chip architectures integrating multiple quantum cores interconnected through quantum-coherent and classical links. The classical communication subsystem is critical for coordinating distributed control operations and supporting quantum protocols such as teleportation. In this work, we consider a realization based on a wireless network-on-chip for implementing classical communication within cryogenic environments. Traditional token-based medium access control (MAC) protocols, however, incur latency penalties due to inefficient token circulation among inactive nodes. We propose the instruction-directed token MAC (ID-MAC), a protocol that leverages the deterministic nature of quantum circuit execution to predefine transmission schedules at compile time. By embedding instruction-level information into the MAC layer, ID-MAC restricts token circulation to active transmitters, thereby improving channel utilization and reducing communication latency. Simulations show that ID-MAC reduces classical communication time by up to 70% and total execution time by up to 30-70%, while also extending effective system coherence. These results highlight ID-MAC as a scalable and efficient MAC solution for future multichip quantum architectures.