Distance-aware bidirectional medium access control for mesh wireless network-on-chip architecture

Abstract

Wireless Network-on-Chip (WiNoC) architectures have recently been proposed to address the scalability limitations of conventional multi-hop wired NoC architectures. The medium access control (MAC) protocol and routing strategy are critical in determining the performance and energy characteristics of a WiNoC. Most conventional WiNoC MAC use a daisy-chained ring topology, which limits the performance benefit of using a wireless channel since daisy-chaining results in a maximum waiting time when a radio hub misses the token before a packet arrives. Furthermore, even when radio hubs are connected to wired paths, all cores connected to the WiNoC radio hub prioritise transmission through the radio hub, resulting in an uncontrolled load on the wireless channel. Therefore, this thesis’s main objectives are as follows. The first objective is to propose a Bidirectional MAC (B!"#) strategy for WiNoC while the second objective is to propose a Distance-Aware (D") routing scheme in conjunction with B!"# (D"+B!"#) to control a single-hop wireless transmission exclusive to far away destination cores. The wired metal planar interconnect has a higher aggregate bandwidth and is dedicated to short-range communication, whereas single-hop wireless channels are dedicated to long-range transmission beyond a certain distance threshold. To determine the effectiveness of the proposed works, a comprehensive validation was performed using the cycle-accurate Noxim simulator. The proposed strategy was tested and validated in terms of latency, throughput, and energy consumption using synthetic traffic distributions (random, shuffle, transpose, and hotspot) and real-application PARSEC (Barnes) and SPLASH-2 (Fluidanimate) traces. Extensive simulation results show that B!"# can achieve up to 1.84 times faster throughput, while D"+B!"# can improve up to 11.49 times faster than the WiNoC baseline daisy-chained architecture. At the same time, the energy improvement over the baseline daisy-chained at the saturated packet injection load is up to 8% for B!"# and 15% for D"+B!"#. The proposed MAC and routing protocols increase wireless channel utilisation and balance wireless-wired load, resulting in significantly improved WiNoC performance over the baseline architecture.