Switching Interconnection Research Articles

On the Unprecedented Scalability of the FISSION (Flexible Interconnection of Scalable Systems Integrated Using Optical Networks) Datacenter

Internet traffic is doubling almost every other year which implies that datacenter (DC) scalability will play a critical role in enabling future communications. In this paper, we propose FISSION (Flexible Interconnection of Scalable Systems Integrated using Optical Networks)—a scalable, fault-tolerant DC architecture based on a switchless optical-bus backplane and carrier-class switches, and its supporting protocol. The FISSION DC enables unprecedented scalability using affordable optics and standardized electrical switches. It is architecturally bifurcated into sectors that internally have a nonblocking carrier-class switching interconnection structure. Sectors are connected in the switchless backplane using optical buses. Each sector can receive traffic on all wavelengths (achieved through optical-bus property without any switch reconfiguration) and across all fibers, but a sector transmits on only a group of wavelengths and only in one of the fiber rings in the backplane. The switches function based on an SDN methodology that facilitate mapping of complex protocols and addresses to DC-specific addressing that is scalable and easier to use. We present an analysis to optimize the FISSION architecture. A simulation model is proposed that (1) compares the FISSION approach to other contemporary designs; (2) provides scalability analysis and protocol performance measurement; and, (3) provides optical layer modeling to validate working of the FISSION framework at high line-rates. Our architecture, which provides 100% bisection bandwidth, is validated by simulation results exhibiting negligible packet loss and low end-to-end latency.

Consensus and formation control on [formula omitted] for switching topologies

This paper addresses the consensus problem and the formation problem on SE(3) in multi-agent systems with directed and switching interconnection topologies. Several control laws are introduced for the consensus problem. By a simple transformation, it is shown that the proposed control laws can be used for the formation problem. The design is first conducted on the kinematic level, where the velocities are the control laws. Then, for rigid bodies in space, the design is conducted on the dynamic level, where the torques and the forces are the control laws. On the kinematic level, first two control laws are introduced that explicitly use Euclidean transformations, then separate control laws are defined for the rotations and the translations. In the special case of purely rotational motion, the consensus problem is referred to as consensus onSO(3) or attitude synchronization. In this problem, for a broad class of local representations or parameterizations of SO(3), including the Axis–Angle Representation, the Rodrigues Parameters and the Modified Rodrigues Parameters, two types of control laws are presented that look structurally the same for any choice of local representation. For these two control laws we provide conditions on the initial rotations and the connectivity of the graph such that the system reaches consensus on SO(3). Among the contributions of this paper, there are conditions for when exponential rate of convergence occurs. A theorem is provided showing that for any choice of local representation for the rotations, there is a change of coordinates such that the transformed system has a well known structure.

Modeling and Characterization of a Nonblocking $4\times 4$ Mach–Zehnder Silicon Photonic Switch Fabric

We present simulation and experimental results on a silicon photonic strictly nonblocking $4\times 4$ electrooptic Mach–Zehnder-based switch fabric. We propose a simulation framework based on the transfer matrix approach that enables calculating the transmission spectra of any type of multistage interconnect switch network. The model is used to analyze the spectral characteristics of the switch fabric. We also show experimental results on a fabric designed and fabricated in IBM's 90-nm photonics-enabled CMOS process. The fabric monolithically integrates the CMOS logic, the switch drivers, and all the photonics. We fully characterized all the transmittances of the switch and demonstrate onchip insertion loss between 1.5 and 3 dB and a crosstalk less than –25 dB for all the signal paths.

Efficient Kernel Integrity Monitor Design for Commodity Mobile Application Processors

In recent years, there are increasing threats of rootkits that undermine the integrity of a system by manipulating OS kernel. To cope with the rootkits, in Vigilare, the snoop-based monitoring which snoops the memory traffics of the host system was proposed. Although the previous work shows its detection capability and negligible performance loss, the problem is that the proposed design is not acceptable in recent commodity mobile application processors (APs) which have become de facto the standard computing platforms of smart devices. To mend this problem and adopt the idea of snoop-based monitoring in commercial products, in this paper, we propose a snoop-based monitor design called S-Mon, which is designed for the AP platforms. In designing S-Mon, we especially consider two design constraints in the APs which were not addressed in Vigilare; the unified memory model and the crossbar switch interconnect. Taking into account those, we derive a more realistic architecture for the snoop-based monitoring and a new hardware module, called the region controller, is also proposed. In our experiments on a simulation framework modeling a production-quality device, it is shown that our S-Mon can detect the rootkit attacks while the runtime overhead is also negligible.

A note on basic consensus problems in multi-agent systems with switching interconnection graphs

We consider several basic consensus problems in multi-agent systems with switching interconnection graphs, where the connections between any two agents are assumed bidirectional for notation simplicity. When the switching interconnection graphs are always connected, it has been shown in the literature that the Laplacian-based algorithm always achieves the average consensus. We first extend the discussion to the case where disconnected interconnection graphs are involved, by showing that the average consensus is still achieved if the dwell time ratio between connected graphs and disconnected ones satisfies a specified condition. Next, we consider the case where there is no connected graph but the combination of a set of graphs is connected, and propose two switching strategies for achieving the average consensus. Several numerical examples are provided to show the algorithms.

Conditions for Existence of Equilibria of Systems With Constant Power Loads

In this paper we investigate the sine qua non condition of existence of equilibria for electrical systems with external (AC or DC) sources furnishing constant power to the loads, which is a scenario encountered in modern applications. Two general cases are considered, when the system is i) linear time-invariant or ii) nonlinear, with dynamic behavior described by a port-Hamiltonian model with constant dissipation and switching interconnection matrix. The latter class includes the practically important case of power converters. For both cases necessary and sufficient conditions for existence of equilibria are given, which give an upper bound on the power dissipated in steady-state that should exceed the extracted constant power. The existence of the equilibrium is ensured if and only if the inequality is satisfied.

Timing-constrained power minimization in VLSI circuits by simultaneous multilayer wire spacing

Reduction of interconnect delay and interconnect power has become a primary design challenge in recent CMOS technology generations. Spacing between wires can be modified so that line-to-line capacitances will be optimized for minimal power under timing constraints. In this paper, we present a novel algorithm for simultaneous multilayer interconnect spacing that minimizes the total dynamic power dissipation caused by an interconnect, while maximum delay constraints are satisfied. A multi-dimensional visibility graph is used to represent the problem, and a layout partitioning technique is applied to solve the problem efficiently. The algorithm was evaluated on an industrial microprocessor designed using the 32nm technology, and it achieved a 5–12% reduction in interconnect switching power.

Distributed attitude synchronization control of multi-agent systems with switching topologies

This paper addresses the attitude synchronization problem in multi-agent systems with directed and switching interconnection topologies. Two cases for the synchronization problem are discussed under different assumptions about the measurable information. In the first case the agents can measure their rotations relative to a global reference coordinate frame, whilst in the second case they can only measure the relative rotations between each other. Two intuitive distributed control laws based on the axis–angle representations of the rotations are proposed for the two cases, respectively. The invariance of convex balls in SO(3) is guaranteed. Moreover, attitude synchronization is ensured under the well-known mild switching assumptions, the joint strong connection for the first case and joint quasi-strong connection for the second case. To show the effectiveness of the proposed control schemes, illustrative examples are provided.

Randomly changing leader-following consensus control for Markovian switching multi-agent systems with interval time-varying delays

This paper considers the problem of leader-following consensus stability and also stabilization for multi-agent systems with interval time-varying delays. The randomly occurring interconnection information of the leader and the Markovian switching interconnection information of the agent are matters of concern in the systems. Through construction of a suitable Lyapunov–Krasovskii functional and utilization of the reciprocally convex approach, new delay-dependent consensus stability and stabilization conditions for the systems are established in terms of linear matrix inequalities (LMIs) which can be easily solved by using various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed methods.

Distributed Estimation for Moving Target Based on State-Consensus Strategy

This technical note studies the distributed estimation problem for a continuous-time moving target under switching interconnection topologies. A recursive distributed estimation algorithm is proposed by using state-consensus strategy, where a common gain is assigned to adjust the innovative and state-consensus information for each sensor in the network. Under mild conditions on observability and connectivity, the stability of the distributed estimation algorithm is analyzed. An upper bound and lower bound for the total mean square estimation error (TMSEE) are obtained by virtue of the common Lyapunov method and Kalman-Bucy filtering theory, respectively. Then a numerical simulation is given to verify the effectiveness of the proposed algorithm.

Second-Order Leader-Following Consensus of Multiagent Systems with Time Delays

This paper is concerned with a leader-following consensus problem of second-order multiagent systems with a constant acceleration leader and time-varying delays. At first, a distributed control protocol for every agent to track the leader is proposed; then by utilizing the Lyapunov-Razumikhin function, the convergence analysis under both fixed and switching interconnection topologies is investigated. For the case of fixed topology, a sufficient and necessary condition is obtained, and for the case of switching topology, a sufficient condition is derived under some assumptions. Finally, simulation examples are provided to demonstrate the effectiveness of the theoretical results.

On Distributed Reduced-Order Observer-Based Protocol for Linear Multiagent Consensus under Switching Topology

We discuss linear multiagent systems consensus problem with distributed reduced-order observer-based protocol under switching topology. We use Jordan decomposition method to prove that the proposed protocols can solve consensus problem under directed fixed topology. By constructing a parameter-dependent common Lyapunov function, we prove that the distributed reduced-order observer-based protocol can also solve the continuous-time multi-agent consensus problem under the undirected switching interconnection topology. Then, we investigate the leader-following consensus problem and propose a reduced-order observer-based protocol for each following agent. By using similar analysis method, we can prove that all following agents can track the leader under a class of directed interaction topologies. Finally, the given simulation example also shows the effectiveness of our obtained result.

Leader—following consensus criteria for multi-agent systems with time-varying delays and switching interconnection topologies

We consider multi-agent systems with time-varying delays and switching interconnection topologies. By constructing a suitable Lyapunov—Krasovskii functional and using the reciprocally convex approach, new delay-dependent consensus criteria for the systems are established in terms of linear matrix inequalities (LMIs), which can be easily solved by using various effective optimization algorithms. Two numerical examples are given to illustrate the effectiveness of the proposed methods.

Target aggregation of second-order multi-agent systems with switching interconnection

In this paper, the target aggregation is investigated for a multi-agent system consisting of second-order agents and multiple leaders. Sufficient conditions are proposed to make the agents approach the target set spanned by these moving leaders. With the condition on switching interconnection topologies, all mobile agents can asymptotically track the dynamical target set specified by multiple moving leaders with bounded error. Moreover, discussion on the case with static leaders is also given.

구간 시변 지연을 고려한 전환 멀티-에이전트 시스템에 대한 일치 제어

This paper considers multi-agent systems with interval time-varying delays and switching interconnection topology. By construction of a suitable Lyapunov-Krasovskii's functional, new delay-dependent consensus control conditions for the systems are established in terms of LMIs (Linear Matrix Inequalities) which can be easily solved by various effective optimization algorithms. One numerical example is given to illustrate the effectiveness of the proposed methods.

Target containment control of multi-agent systems with random switching interconnection topologies

In this paper, the distributed containment control is considered for a second-order multi-agent system guided by multiple leaders with random switching topologies. The multi-leader control problem is investigated via a combination of convex analysis and stochastic process. The interaction topology between agents is described by a continuous-time irreducible Markov chain. A necessary and sufficient condition is obtained to make all the mobile agents almost surely asymptotically converge to the static convex leader set. Moreover, conditions on the tracking estimation are provided for the convex target set determined by moving multiple leaders.

Leader-Following Formation of Switching Multirobot Systems via Internal Model

In this paper, the leader-following formation problem of multirobot systems with switching interconnection topologies is considered. The robots are required to move in a formation with formation constrains described in terms of relative distances of the robots and the formation (as whole entity) is required to track the trajectory generated by an exosystem. The exosystem of the considered multirobot systems provides driving forces or environmental disturbance, whose dynamics is different from the dynamics of the robots. A systematic distributed design approach for the leader-following formation problem is proposed via dynamic output feedback with the help of canonical internal model.

A Self-healing Scheme of Single-phase-to-ground Fault in Smart Power Distribution System

The paper presents a self-healing scheme of single-phase-to-ground fault in smart power distribution system. The scheme consists of three parts: single-phase-to-ground fault detection, faulted feeder selection and faulted feeder isolation. Fault detection is based on power-frequency voltage measured by a voltage transducer. A single-phase-to-ground fault is detected when measured voltage is greater than threshold. A fault generated current traveling waves are used to identify faulted feeder. The feeder with different initial traveling wave's polarity to other feeders is selected as faulted feeder. When faulted feeder is identified, the interconnection switch between different bus-bar is switched on firstly, then the switch at the load side of faulted feeder is switched off to isolate the load from the fault, the switch at the power source side of faulted feeder is switched off to isolate the source from the fault lastly. Simulation studies show that the scheme can meet the requirements of isolating single-phase-to-ground fault without affecting power supply to the load.

Distributed output regulation of leader–follower multi‐agent systems

SUMMARYIn this paper, distributed leader–follower control algorithms are presented for linear multi‐agent systems based on output regulation theory and internal model principle. By treating a leader to be followed as an exosystem, the proposed framework can be used to generalize existing multi‐agent coordination solutions to allow the identical agents to track an active leader with different dynamics and unmeasurable variables. Moreover, the obtained results for multi‐agent coordination control are an extension of previous work on centralized and decentralized output regulation to a distributed control context. Necessary and sufficient conditions for the distributed output regulation problem are given. Finally, distributed output regulation of some classes of multi‐agent systems with switching interconnection topologies are discussed via both static and dynamic feedback. Copyright © 2011 John Wiley & Sons, Ltd.

Single event upset induced multi-block error and its mitigation strategy for SRAM-based FPGA

According to the SRAM-based FPGA’s single event effect problem in space application, single event upset induced multi-block error (SEU-MBE) phenomenon and its mitigation strategy are studied in the paper. After analyzing the place and route result, the paper points out that the essence of SEU-MBE is that some important modules exceed the safe internal distance. Two approaches, area constraint method (ACM) and incremental route algorithm (IRA), are proposed, which can reduce the error rate by manipulating programmable switch matrix and interconnection points within FPGA route resource. Fault injection experiments indicate that error detection rate is above 98.6% for both strategies, and FPGA resources increment and performance penalty are around 10%.