text: Advances in CMOS-compatible photonic elements have made it plausible to exploit nanophotonic communications to overcome the limitations of traditional NoCs. Amongst various proposed nanophotonic architectures, optical crossbars have been shown to provide high performance in terms of bandwidth and latency. In general, optical crossbars provide a vast volume of network resources that are shared among all the cores within the chip. In this paper, we present a fair and efficient admission control mechanism for shared wavelengths and buffer space in optical crossbars. We model buffer management and wavelength assignment as a utility-based convex optimization problem, whose solution determines the admission control policy. Thanks to efficient convex optimization techniques, we obtain the globally optimal solution of the admission control optimization problem by using simple and yet efficient iterative algorithms. We cast our solution procedure as an iterative algorithm to be implemented a central admission controller. Our experimental results corroborate the gain that can be obtained by using such an admission controller to manage the shared resources of the system. Furthermore, they confirm that the proposed admission control algorithm works well for various traffic patterns and parameters, and evinces a tractable scalability with increase in the number of cores of the crossbar.
  @cite_37: This article proposes a scalable wavelength-routed optical Network on Chip (NoC) based on the Spidergon topology, named Power-efficient Scalable Wavelength-routed Network-on-chip (PeSWaN). The key idea of the proposed all-optical architecture is the utilization of per-receiver wavelengths in the data network to prevent network contention and the adoption of per-sender wavelengths in the control network to avoid end-point contention. By performing a series of simulations, we study the efficiency of the proposed architecture, its power and energy consumption, and the data transmission delay. Moreover, we compare the proposed architecture with electrical NoCs and alternative ONoC architectures under various traffic patterns.
  @cite_1: 
  @cite_52: This paper proposes CoNoC (Contention-free optical NoC) as a new architecture for on-chip routing of optical packets. CoNoC is built upon all-optical switches (AOSs) which passively route optical data streams based on their wavelengths. The key idea of the proposed architecture is the utilization of per-receiver wavelength in the data network to prevent optical contention at the intermediate nodes. Routing optical packets according to their wavelength eliminates the need for resource reservation at the intermediate nodes and the corresponding latency, power, and area overheads. Since passive architecture of the AOS confines the optical contention to the end-points, we propose an electrical arbitration architecture for resolving optical contention at the destination nodes. By performing a series of simulations, we study the efficiency of the proposed architecture, its power and energy consumption, and the data transmission latency. Moreover, we compare the proposed architecture with electrical NoCs and alternative ONoC architectures under various synthetic traffic patterns. Averaged across different traffic patterns, the proposed architecture reduces per-packet power consumption by 19 , 28 , 29 , and 91 and achieves per-packet energy reduction of 28 , 40 , 20 , and 99 over Columbia, Phastlane, @l-router, and electrical torus, respectively.
  @cite_17: Optical networks-on-chip constitute a promising approach to tackle the power wall problem present in large-scale circuit design. In this paper, we propose Amon, an all-optical, mesh-like design based on passive microrings and wave-length division multiplexing, including the switch architecture and a contention-free routing algorithm. Amon provides power efficiency by decreasing the number of microrings, wavelengths and path lengths, which, in turn, reduces ring heater and laser power, and the required area. An analytic comparison of Amon against the state-of-the-art, low power, ring-based designs QuT and Spidergon shows that Amon significantly reduces network diameter and number of microrings. Our experimental results using DSENT show that Amon provides better scalability up to 256 nodes, significant power and area savings of up to 68 and 21 , respectively, while imposing only low wiring overhead and design complexity. Finally, Amon provides a tile-based structure which should facilitate VLSI integration.
summary: @cite_1 use 4-port optical switches to build a photonic routing structure called @math , which provides contention-free communication among cores through wavelength routing techniques. Each pair of cores communicate through fixed and predefined wavelengths routed passively by the @math -router. is the architecture proposed by @cite_52 , where all-optical switches are used to implement contention-free wavelength-based passive routing of optical streams. Contention-free communication is carried out by assigning each node with a unique wavelength for data reception. This way, contention is confined to the end-points and is resolved by an electrical arbitration scheme. A scalable wavelength-routed optical NoC based on the Spidergon topology is presented in @cite_37 . It uses per-receiver wavelengths in the data network to prevent network contention, and adopts per-sender wavelengths in the control network to avoid end-point contention. @cite_17 also propose an all-optical design exploiting a mesh-like topology.