Combined TDM and SDM Circuit Switching NoCs with Dedicated Connection Allocator

In general, circuit switching (CS) NoCs suffer from path diversity and resource utilization problem. Combining Time-Division Multiplexing (TDM) and Space-Division-Multiplexing (SDM) CS NoCs can reasonably mitigate this problem by increasing the path diversity and improving sharing of sub-channel among multiple connections. In order to investigate and optimize TDM-SDM partitioning strategy, in this paper, we propose a dedicated connection allocator for combined TDM-SDM CS NoCs based on trellis-search algorithm, which can explore all possible paths between source-destination node pairs within a guaranteed latency. In contrast to the recently published approaches, we propose the novel bidirectional search that starts at source node and destination node simultaneously. Compared to previous unidirectional trellis search algorithms, our algorithm halves the search time while keeping the allocator area almost the same. In addition to this, we studied the influence of different TDM-SDM link partitioning strategies on success rate and path length that allowed us to find the optimal solution. The simulation results show our approach can improve the success rate by 25% to 42% compared to previous connection allocation approaches.