TRMAC: A Time-Reversal-based MAC Protocol for Wireless Networks within Computing Packages

2025-06-24

AI Summary

To address the limited MAC scalability of wireless networks-on-chip (WNoCs) under high-traffic density and constrained spectrum, this paper proposes a cross-layer MAC protocol leveraging time reversal (TR). Exploiting TR’s physical-layer channel spatiotemporal focusing property, the protocol enables concurrent multi-pair transmissions on a single frequency band—without orthogonal resource allocation or centralized scheduling—by pre-characterizing channel impulse responses and employing dynamic energy-detection thresholds. Experimental results demonstrate that, at hundreds of cores, the protocol achieves latency and throughput comparable to multi-band approaches while significantly improving spatial reuse efficiency. Crucially, it avoids complex transceiver designs, substantially reducing hardware overhead and protocol complexity. The core innovation lies in the first deep integration of TR’s intrinsic physical characteristics into MAC-layer design, enabling low-overhead, highly scalable single-band concurrent communication.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Multiagent Systems: Agent Communication
• Machine Learning: Hardware-aware ML

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines

Abstract

As chiplet-based integration and many-core architectures become the norm in high-performance computing, on-chip wireless communication has emerged as a compelling alternative to traditional interconnects. However, scalable Medium Access Control (MAC) remains a fundamental challenge, particularly under dense traffic and limited spectral resources. This paper presents TRMAC, a novel cross-layer MAC protocol that exploits the spatial focusing capability of Time Reversal (TR) to enable multiple parallel transmissions over a shared frequency channel. By leveraging the quasi-deterministic nature of on-chip wireless channels, TRMAC pre-characterizes channel impulse responses to coordinate access using energy-based thresholds, eliminating the need for orthogonal resource allocation or centralized arbitration. Through detailed physical-layer simulation and system-level evaluation on diverse traffic, TRMAC demonstrates comparable or superior performance to existing multi-channel MAC protocols, achieving low latency, high throughput, and strong scalability across hundreds of cores. TRMAC provides a low-complexity, high-efficiency solution for future Wireless Networks-on-Chip (WNoCs), particularly in chiplet-based systems where spatial reuse and modularity are critical. With simulations we prove that TRMAC can be utilized for parallel transmissions with a single frequency channel with a similar throughput and latency as in using multiple frequency bands omitting the need for complex transceivers. This work establishes a new design direction for MAC protocols that are tightly integrated with the underlying channel physics to meet the demands of next-generation computing platforms.

Problem

• Scalable MAC for on-chip wireless networks under dense traffic
• Enable parallel transmissions over shared frequency channels
• Low-complexity solution for Wireless Networks-on-Chip scalability

Innovation

• Time Reversal enables parallel wireless transmissions
• Energy-based thresholds replace orthogonal allocation
• Single-channel performance matches multi-channel systems