Exploration of a scalable and power-efficient asynchronous Network-on-Chip with dynamic resource allocation

Most Network-on-Chip routers dedicate a set of buffers to the input and/or output ports. This design decision leads to buffer underuti-lization especially when running applications with non-uniform traffic patterns. In order to maximize resource usage for performance and energy gains, we present a synchronous and elastic buffer implementation of a router architecture called Roundabout with intrinsic resource sharing. Roundabout is inspired by real-life traffic roundabouts and consists of lanes shared by multiple input and output ports. Roundabout offers performance improvement of 61% for uniform traffic pattern and up to 88% for non-uniform traffic pattern over the Hermes router, a typical input buffered router. In terms of power, it consumes 24% less than the Hermes router. Roundabout provides a highly parametric architecture that can produce different router configurations with varying topological trade-offs for performance gains without sacrificing area.

The function of power divider is to divide to power from one input port into the divided power at multiple output ports, or to combine the power from multiple ports into the combined power at one output port. The goal of this study is to design a millimeter-wave power divider operating at the range from 32 GHz to 34 GHz. The return loss at each port and the isolation between from output ports are required to be greater than 15 dB. The insertion loss need to be less than 3.1 dB. The concept of E-plane bifurcated waveguide is proposed to implement this millimeter-wave power divider because of the concerns about operation at high-frequencies and high-power handling, capacity. A resistive film is placed inside the bifurcated waveguide in order to meet the specifications of the proposed power divider. In addition, impedance transformation is employed at output ports to convert the output waveguide to standard waveguide.

The rising computational demand of modern workloads has renewed interest in energy-efficient paradigms such as neuromorphic and analog computing. A fundamental operation in these systems is matrix-vector multiplication (MVM), ubiquitous in signal processing and machine learning. Here, we demonstrate MVM using inverse-designed metastructures that exploit heat conduction as the signal carrier. The proposed approach is based on a generalization of effective thermal conductivity to systems with multiple input and output ports: The input signal is encoded as a set of applied temperatures, while the output is represented by the power collected at designated terminals. The metastructures are obtained via density-based topology optimization, enabled by a differentiable thermal transport solver and automatic differentiation, achieving an accuracy $>99\%$ in most cases across a pool of matrices with dimensions $2\times2$ and $3\times3$. We apply this methodology -- termed thermal analog computing -- to realize matrices relevant to practical tasks, including the discrete Fourier transform and convolutional filters. These findings open new avenues for analog information processing in thermally active environments, including temperature-gradient sensing in microelectronics and thermal control systems.

As traffic volumes carried by optical networks continue to grow by tens of percent year over year, we are rapidly approaching the capacity limit of the conventional communication band within a single-mode fiber. New measures such as elastic optical networking, spectral extension to multi-bands, and spatial expansion to additional fiber overlays or new fiber types are all being considered as potential solutions, whether near term or far. In this tutorial paper, we survey the photonic switching hardware solutions in support of evolving optical networking solutions enabling capacity expansion based on the proposed approaches. We also suggest how reconfigurable add/drop multiplexing nodes will evolve under these scenarios and gauge their properties and relative cost scalings. We identify that the switching technologies continue to evolve and offer network operators the required flexibility in routing information channels in both the spectral and spatial domains. New wavelength-selective switch designs can now support greater resolution, increased functionality and packing density, as well as operation with multiple input and output ports. Various switching constraints can be applied, such as routing of complete spatial superchannels, in an effort to reduce the network cost and simplify the routing protocols and managed pathway count. However, such constraints also reduce the transport efficiency when the network is only partially loaded, and may incur fragmentation. System tradeoffs between switching granularity and implementation complexity and cost will have to be carefully considered for future high-capacity SDM–WDM optical networks. In this work, we present the first cost comparisons, to our knowledge, of the different approaches in an effort to quantify such tradeoffs.

In this paper, we purpose a novel approach to analyze exact cell loss probability of Shared Buffer ATM switch. In a N X N ATM switch whose input ports and output ports share one buffer, the number of arriving cells from input ports at one time slot is less than or equal to N. If these cells were destined to n output ports, no cells will be destined to the remaining N-n output ports. In the extremism, all arriving cells were destined to one output port, no cell will be destined to the other N-1 output ports. So, the arriving cells at each time slot from the input ports are destined to the output ports correlatively, but not independently. For this reason, the analyzing result on the assumption that all output cell queues are independent one another is larger than actual result. We complete our analysis by three steps. First, considering the case that there are cells arriving from input ports but not cells remove from output ports, we can get one-step state transition probability matrix P<SUB>a</SUB>; Second, considering the case that there are cells removing from output ports but not cells arrive from input ports, we can get one-step state transition probability matrix Ps; Third, considering arrival process and service process are independent, the accurate one-step state transition probability matrix P of cell's number in the buffer is derived, and then cell queue length steady probability distribution can be found. We can compute the accurate buffer capacity below certain cell loss probability. Computer simulation proves that the approach is efficient and exact.

This paper presents a model that can be easily used to resolve the energy hub operation problem. The proposed model considers the uncertainty in the input and output ports. The energy hub optimum operation problem needs to be resolved in order to supply several energy loads in combination at the minimum total energy cost. In this study, mixed-integer linear programming was applied to formulate this optimization problem. The power balance, energy storage, and converter limitations of the input and output ports were included as equality and inequality constraints. The total cost of an energy hub was determined by the price of energy carriers. Eventually, deterministic and stochastic versions of the proposed model were tested in a case study. In the test system, electricity, gas, and wind generation were used in the input port, and the output port contained the electrical and thermal load. The results demonstrated that a stochastic model based on different scenarios was more realistic than a deterministic model. However, the total operating cost of an energy hub decreased more in the stochastic model compared to the deterministic model.

This paper presents a III/V compound silicon (Si) and gallium arsenide (GaAs) metasurface antenna to achieve beam-forming at 94 GHz. The metasurface antenna consists of a flat-panel system architecture and works in a holographic manner. The guided mode launched into the Si layer is converted to a planar wave-front using a quasi-optical pillbox feeding architecture, significantly simplifying the design process of the metasurface antenna. It is demonstrated that the developed metasurface can switch its radiation pattern in the azimuth plane by selectively activating between multiple input ports while beam forming in the elevation plane can be achieved by actively tuning the metamaterial elements forming the metasurface aperture. The simulated reflection coefficient patterns suggest an impedance matching better than -15dB at all input ports is achieved at 94 GHz. The radiation patterns of the antenna clearly demonstrate the 3D beam scanning capability of the presented metasurface antenna $(\theta =0^{\circ }/15^{\circ },\varphi =0^{\circ }/\pm 90^{\circ })$ at millimeter-wave frequencies.

A formulation for design of continuous, hinge-free compliant mechanisms is developed and examined within a continuum structural topology optimization framework. The formulation makes use of two distinctly different sets of springs, the first of which are artificial springs of relatively large stiffness attached to the input and output ports of the mechanism model, and the second of which are springs attached only to the output port with smaller stiffnesses that represent the resistance of the workpiece as it is manipulated by the mechanism. The proposed formulation involves solving two nested optimization problems. In the inner problem the arrangement of a constrained amount of structural material is optimized to maximize the mechanism's mutual potential energy in response to a force loading at the input port while working against the stiff artificial springs on the input and output ports. As the relative stiffness of the artificial springs increases, the material continuity of the mechanism also increases to the point where de facto ‘hinge’ regions are eliminated. In the outer problem, the artificial springs are removed and one solves for an appropriate amount of structural material that yields the desired finite deformation compliance characteristics of the mechanism when working against the real workpiece resistance. Different aspects of the proposed formulation are demonstrated on a number of examples and discussed. Copyright © 2004 John Wiley & Sons, Ltd.

This article investigates resource allocation in ATM networks and emphasizes bandwidth allocation. Resource allocation methods are categorized, and static and dynamic allocation strategies are compared. Dynamic allocation uses actual traffic behavior, while static allocation uses only the reference traffic condition given a priori. Examples of dynamic allocation strategies are available bit rate flow control, dynamic connection admission control, and dynamic VP bandwidth control. Dynamic resource allocation is shown to be promising for situations where the a priori reference model is unclear.

We describe a novel method for scheduling highspeed network switches. The targeted architecture is an input-buffered switch with a non-blocking switch fabric. The input buffers are organized as virtual output queues to avoid head-of-line blocking. The task of the scheduler is to decide when the input ports can forward packets from the virtual output queues to the corresponding output ports. Our Least Choice First (LCF) scheduling method selects the input and output ports to be matched by prioritizing the input ports according to the number of virtual output queues that contain packets: The fewer virtual output queues with packets, the higher- the scheduling priority, of the input port. This way the number- of switch connections and, with it, switch throughput is maximized. Fairness is provided through the addition of a round-robin algorithm. We present two alternative implementations: A central implementation intended for narrow, switches and a distributed implementation based on an iterative algorithm intended for wide switches. The simulation results show that the LCF scheduler outperforms other scheduling methods such as the parallel iterative matcher, iSLIP, and the wave front arbiter.

Networks-on-Chip (NoCs) have become the de-facto on-chip interconnect for multi/manycore systems. A typical NoC router is made up of buffers used to store packets that are unable to advance to their desired destination. However, buffers consume significant power/area and are often underutilized, especially in cases of applications with non-uniform traffic patterns thus leading to performance degradation for such applications. To improve network performance, the Roundabout NoC (R-NoC) concept is considered. R-NoC is inspired by real-life multi-lane traffic roundabouts and consists of lanes that are shared by multiple input/output ports to maximize buffering resource utilization. R-NoC relies on router-internal adaptive routing that decides the lane path based on back pressure. Back pressure makes it possible to assess lane utilization and route packets accordingly. This is made possible thanks to the use of elastic buffers for control flow, a clever type of handshaking in a way similar to asynchronous circuits. Another prominent feature of R-NoC is that internal routing and arbitration are completely distributed which allows for significant freedom in deciding internal router topology and parameters. This work leverages this property and proposes novel yet unexplored configurations for which an in-depth evaluation of corresponding implementations on 45 nm CMOS technology is given. Each configuration is evaluated performance and power-wise on both synthetic and real application traffic. Several R-NoC configurations are identified and demonstrated to provide very significant performance improvements over standard mesh configurations and a typical input-buffered router, without compromising area and power consumption. Exploiting the distributed nature of R-NoC routers, a diagonally-linked configuration is then proposed which incurs moderate area overhead and features yet better performance and energy efficiency.

With the advent of gaining popularity in cloud computing, there is an increase in demand of resources among the heterogeneous workload types on cloud. Resource management is a key challenging problem that is faced by the cloud service providers, by achieving business goals and agreed level of service with the subscribers. This paper focuses on dynamic resource allocation with risk analysis by meeting service level agreements. Further proposed framework handles heterogeneous workload types by dynamic capacity planning with risk assessment to maximise the profit and resource utilisation on clouds. In addition to advanced resource reservation, SLA-based scheduling/rescheduling with risks involved in resource allocation is considered in the proposed model. The experimental results demonstrate that proposed framework maximises the resource utilisation and profit gain of the cloud service provider when evaluated against widely used static configuration strategy.

We highlight the advantages of dynamic wavelength allocation and path rerouting in hybrid optical flow-switched data center networks compared with static electronic packet-switched data center networks. Current electronic packet-switched networks perform routing based on lookup tables and shortest path routing over high speed optical connections. However, load balancing and path rerouting are not designed in coordination with the optical data plane. In this work, we design and analyze the performance of load balancing and resource allocation in hybrid flow data center architectures. In the hybrid flow architecture, the transport layer and control plane are responsible for load balancing, congestion control and reliable data delivery in wavelength division multiplexed networks. The transport layer abstracts the underlying network and data link layers from user applications. Applications are unaware of whether flows are transmitted via the electronic data plane, optical data plane, or both, where the relevant metric for applications is transaction delay. We show that the data center architecture that minimizes delay in the presence of elephant flows and dynamic loads is the hybrid flow architecture with dynamic resource allocation.

In view of the fact that the limited wireless resources and the asymmetric traffic between uplink and downlink in the trunking communication system based on TD-SCDMA network, a design scheme of dynamic resource allocation (DCA) is given. DCA is a very effective technology to solve those problems and enhance the utilization of resource. Based on the characteristics of the trunking communication system, we combine with the DCA algorithms of TD-SCDMA network in this paper, and give an optimal DCA strategy for the truking communication system in TD-SCDMA network. Finally, the simulation result shows the DCA strategy markedly improve the system performance and gain higher resource utilization.

This paper presents a novel, scalable, and modular multiport power electronic topology for the integration of multiple resources. This converter is not only scalable in terms of the integration of multiple renewable energy resources (RES) and storage devices (SDs) but is also scalable in terms of output ports. Multiple dc outputs of a converter are designed to serve as input to the stacking modules (SMs) of the modular multilevel converter (MMC). The proposed multiport converter is bidirectional in nature and superior in terms of functionality in a way that a modular universal converter is responsible for the integration of multiple RES/SDs and regulates multiple dc output ports for SMs of MMC. All input ports can be easily integrated (and controlled), and output ports also can be controlled independently in response to any load variations. An isolated active half-bridge converter with multiple secondaries acts as a central hub for power processing with multiple renewable energy resources that are integrated at the primary side. To verify the proposed converter, a detailed design of the converter-based system is presented along with the proposed control algorithm for managing power on the individual component level. Additionally, different modes of power management (emulating the availability/variability of renewable energy sources (RES)) are exhibited and analyzed here. Finally, detailed simulation results are presented in detail for the validation of the proposed concepts and design process.