A MAC Protocol with Time Reversal for Wireless Networks within Computing Packages

TL;DR

A simple yet resilient TR-based MAC protocol (TR-MAC) design that can be employed in massive computing architectures with improved latency and throughput while matching with the stringent requirements of the physical layer is explored.

Abstract

Wireless Network-on-Chip (WNoC) is a promising concept which provides a solution to overcome the scalability issues in prevailing networks-in-package for many-core processors. However, the electromagnetic propagation inside the chip package leads to energy reverberation, resulting in Inter-Symbol Interference (ISI) with high delay spreads. Time Reversal (TR) is a technique that benefits the unique time-invariant channel with rich multipath effects to focus the energy to the desired transceiver. TR mitigates both ISI and co-channel interference, hence providing parallel communications in both space and time. Thus, TR is a versatile candidate to improve the aggregate bandwidth of wireless on-chip networks provided that a Medium Access Control (MAC) is used to efficiently share the wireless medium. In this paper, we explore a simple yet resilient TR-based MAC protocol (TR-MAC) design for WNoC. We propose to manage multiple parallel transmissions with simultaneous spatial channels in the same time slot with TR precoding and focused energy detection at the transceiver. Our results show that TR-MAC can be employed in massive computing architectures with improved latency and throughput while matching with the stringent requirements of the physical layer.

Figures (7)

• Figure 1: Summary of TR Communication Framework
• Figure 2: Illustration of TR-MAC Protocol. Leftmost plot represents three successful parallel transmissions without collision. Second plot represents a collision in Phase I due to simultaneous preamble transmissions to node 2. Third plot shows how the collision leads to the original senders not receiving an acknowledgment. Rightmost plot represents the possibility of an erroneous acknowledgment affecting a third transmission.
• Figure 3: Flowchart of the TR-MAC protocol.
• Figure 4: Latency-throughput curve of TR-MAC and the baseline protocols in an scenario with 64 cores with (a) two channels, (b) three channels, and (c) four channels.
• Figure 5: Performance of TR-MAC with increasing number of allowed parallel transmissions (NPT) with 64 cores.