Evaluation of hop count advantages of network-coded 2D-mesh NoCs

Abstract

Network-on-Chip (NoC) have become favorable for on-chip communication, especially with the ever rising number of communication partners in future manycore system-on-chip. NoCs that are based on mesh topologies with dimension-routing are well-established as they scale well with the increasing number of communication partners and allow efficient router design. To be able to serve application demands with efficiency, sophisticated features such as multicasting become an increasingly important factor in future NoC-based systems. The 2D-mesh/dimension-routing combination, however, suffers from performance degradation especially in the case of multicast communication as the network infrastructure is utilized suboptimally. Approaching this problem, we investigate the potential of network-coded Network-on-Chip (ncNoC) compared to classical 2D-mesh/dimension-routing NoCs. We adapt a high level evaluation method to compute the minimum hop count equivalent using network coding which enables us to compare network-coded and dimension-routed hop count cost. Within this environment we can demonstrate the full potential of network coding for both the butterfly and generalized multicast connection settings. We can show that network coding is never outperformed by dimension-routing in terms of required hop counts and, more important, identify multi-source scenarios with only a limited number of sinks per source to be the most advantageous connection settings for coded NoCs.