Deterministic Multiplexing of NoC on Grid CMPs

As the number of cores in a chip has increased over the past several years, the problem of inter-core communication has become a bottleneck. Traditional bus architectures cannot handle the traffic load for the increasingly large number of communicating units on chip. Using a nanophotonic Network-on-Chip(NoC) is a proposed solution that is motivated by recent research indicating a higher throughput over electronic NoCs. In order to avoid optical/electronic/optical conversion at intermediate routers, all-to-all connectivity can be achieved through Time-Division-Multiplexing (TDM). Previous work has focused on using a non-deterministic approach to determine the multiplexing schedule in optically connected mesh NoCs. Such an approach, however, produces an irregular schedule that is not scalable, especially if TDM is to be combined with wavelength-division multiplexing (WDM) and space-division multiplexing to reduce the communication delay. In this work, we present a regular multiplexing schedule for all-to-all connectivity which is at least as efficient as the previously introduced irregular schedule. Moreover, because of its regularity and its systematic construction, our schedule is scalable to arbitrary-size meshes and allows for efficient combination of TDM, WDM and space division multiplexing (the use of multiple NoCs).