Compact distributed RLC interconnect models. I. Single linetransient, time delay, and overshoot expressions

Novel compact expressions that describe the transient response of a high-speed distributed resistance, inductance, and capacitance (RLC) interconnect are rigorously derived with on-chip global interconnect boundary conditions. Simplified expressions enable physical insight and accurate estimation of transient response, time delay, and overshoot for high-speed global interconnects with the inclusion of inductance     

Compact physical models for multilevel interconnect crosstalk in gigascale integration (GSI)

For the first time, compact physical models are derived for crosstalk noise of coplanar resistance-inductance-capacitance lines in a gigascale integration (GSI) chip that simultaneously consider far and near aggressors in both the same metal level and distant metal levels. Since both the amplitude and duration of noise are important, the noise voltage-time integral can be defined as a figure-of-merit for crosstalk, and it is shown that this integral attains its maximum at the length at which the interconnect resistance becomes equal to twice the characteristic impedance. It is also shown that crosstalk can be prohibitively large if interconnects have small resistances. There is, therefore, a tradeoff between interconnect latency and crosstalk. The compact models are finally used to calculate the crosstalk noise voltage for the case that wire width is optimized by simultaneously maximizing data flux density and minimizing latency. It has been proven that by utilizing the optimal wire width for signal interconnects and twice of that for power and ground lines, the worst case peak crosstalk noise voltage becomes smaller than 0.25 V/sub dd/ for all generations of technology.     

Modelling delay and crosstalk in VLSI interconnect for electricalsimulation

A method for extracting the multi-pen equivalent network of a system of m distributed RC lines is presented. The technique enables the time delays and crosstalk between interconnects to be efficiently analysed by employing conventional circuit simulators     

Modeling of interconnect capacitance, delay, and crosstalk in VLSI

Increasing complexity in VLSI circuits makes metal interconnection a significant factor affecting circuit performance. In this paper, we first develop new closed-form capacitance formulas for two major structures in VLSI, namely: (1) parallel lines on a plane and (2) wires between two planes, by considering the electrical flux to adjacent wires and to ground separately. We then further derive closed-form solutions for the delay and crosstalk noise. The capacitance models agree well with numerical solutions of three-dimensional (3-D) Poisson equation as well as measurement data. The delay and crosstalk models agree well with SPICE simulations     

RAPID: reconfigurable and scalable all-photonic interconnect for distributed shared memory multiprocessors

In this paper, we describe the design and analysis of a scalable architecture suitable for large-scale distributed shared memory (DSM) systems. The approach is based on an interconnect technology which combines optical components and a novel architecture design. In DSM systems, numerous shared memory transactions such as requests, responses and acknowledgment messages propagate simultaneously in the network. As the network size increases, network contention results in increasing the critical remote memory access latency, which significantly penalizes the performance of DSM systems. In our proposed architecture called reconfigurable and scalable all-photonic interconnect for distributed-shared memory (RAPID), we provide high connectivity by maximizing the channel availability for remote communication to reduce the critical remote latency. RAPID provides fast and efficient unicast, multicast and broadcast capabilities using a combination of aggressively designed wavelength division multiplexing (WDM), time division multiplexing (TDM), and space division multiplexing (SDM) techniques. RAPID is wavelength-routed, permitting the same limited set of wavelength to be reused among all processors. We evaluated RAPID based on network characteristics, power budget criteria, and by simulation using synthetic traffic workloads and compared it against other networks such as electrical ring, torus, mesh, and hypercube networks. We found that RAPID outperforms all networks and still provides good performance as the network is scaled to very large numbers.     

Coherent and incoherent crosstalk in WDM optical networks

The impact of coherent and incoherent crosstalk on an optical signal passing through optical cross-connect nodes (OXC's) in wavelength division multiplexing (WDM) optical networks is studied, and the analytical expressions are given. Such crosstalk will be generated when the optical propagation delay differences of optical paths in an OXC do not exceed the coherent time of the lasers. While causing fluctuation of signal power, coherent crosstalk may cause noise or not, depending on the relationship between the optical propagation delay differences and the time duration of one bit of the signal. Incoherent crosstalk may cause very high noise power, because it can be a coherent combination of crosstalk contributions. The statistical impact of all crosstalk contributions on signal is studied by simulation, and the concept of quantile is proposed to relax the crosstalk specification requirement for components. The crosstalk specification requirements are then obtained for components used in WDM optical networks with different scales     

Accurate in situ measurement of peak noise and delay change inducedby interconnect coupling

An accurate in situ noise and delay measurement technique that considers interconnect coupling effects is presented. This paper improves upon previous work by proposing (1) a novel accurate peak detector to measure on-chip crosstalk noise, and (2) in situ measurement structure to characterize the dynamic delay effect. A test chip was fabricated using 0.35-μm process and measured results demonstrate the effectiveness of the proposed technique. Noise peak measurements show 40-60 mV (1.8% average) accuracy to simulation results and dynamic delay change curve match well with SPICE. The proposed measurement technique can be used for interconnect model verification and calibration, and has applications to various design automation tools such as noise-aware static timing analysis     

Pump depletion induced noise and crosstalk in distributed opticalfiber Raman amplifiers

In distributed optical fiber Raman amplifiers, instantaneous pump power depletion is related to the patterns of the input wavelength-division-multiplexing signals, especially for high bit rate application. This results in additional optical noise and interchannel crosstalk. We analyzed the phenomenon and presented simulation results. The cases for different bit rates and channel numbers were compared     

Experimental study of interband and intraband crosstalk in WDM networks

The impacts of interband and intraband erosstalk are studied and compared experimentally. Results show that interband crosstalk can be removed with narrow-band filters and has no influence on signal. Intraband crosstalk will result in signal eye diagram close and BER increasing. When the polarization states of signal and crosstalk align, intraband crosstalk seriously decreases signal quality. But when they misalign, it has little influence. Coherent and incoherent crosstalk are studied experimentally. Results show that coherent crosstalk is less harmful to system performance than incoherent crosstalk.     

Adaptive crosstalk cancellation and laser frequency driftcompensation in dense WDM networks

Two variations of the LMS algorithm are proposed to cancel received linear crosstalk in dense WDM networks. Analysis and simulations show that with the addition of a few photodetectors, channel spacing requirements can be reduced by over 50 percent. Simulations using a demultiplexer with Gaussian bandpass characteristics show that a 2.5 dB signal-to-crosstalk-plus-noise ratio can be increased to over 35 dB. The decision-directed algorithm will work with OOK data or any intensity modulation scheme which uses the absence of light as one symbol. The decision-directed algorithm makes assumptions on the desired laser frequency so it can accommodate only limited laser drift. A second cancellation algorithm uses pilot tones added to each laser signal in order to cancel the crosstalk. It will work with analog or digital intensity-modulated data and will automatically configure itself to account for laser drift. Both algorithms are blind in that they do not require training sequences for initialization. Analysis shows that weights derived from pilot tones are nearly optimum for canceling crosstalk for the data. Simulations of both algorithms are presented. Finally both algorithms are shown to be capable of canceling nonlinear beating terms     

rDFD: reactive distributed fault detection in wireless sensor networks

Generally, fault detection approaches pursue high detection accuracy, but neglect energy consumption due to the high volume of messages exchanged. Therefore, in this work we propose a reactive distributed scheme for detecting faulty nodes. The scheme is able to detect transient and permanent faulty nodes accurately by exchanging fewer messages. In existing fault detection schemes, nodes exchange too many messages after every specific interval to detect suspicious node. However, in the proposed scheme comparatively much less messages are exchanged within a limited geographical area around the suspicious node only and that too when the node suspects its own readings. In the proposed scheme, each node exploits the temporal correlation in its own readings to detect any suspicious behavior. In order to confirm its status, the suspicious node communicates with its immediate neighbors who may be locally good or possible faulty with a certain level of confidence. Thus, the scheme utilizes the strength of both spatial and temporal correlation to find faulty nodes. Also, a confidence level is assigned to each correlated neighbor of suspicious node in order to enhance the detection accuracy. The ns-2 based simulation results show that our scheme performs better by reducing communication overhead and by detecting faulty nodes with high accuracy as compared to existing approaches.     

FrogSim: distributed graph coloring in wireless ad hoc networks

Graph coloring, which is at the heart of several problems arising in wireless ad hoc networks, concerns the problem of assigning colors to the nodes of a graph such that adjacent nodes do not share the same color. This paper deals with the problem of generating valid colorings in a distributed way, while minimizing the number of colors used. Examples of related problems in wireless ad hoc networks are TDMA slot assignment, wakeup scheduling, and data collection. The presented algorithm is inspired by the desynchronization observed in the context of the calling behaviour of male Japanese tree frogs. Experimental results indicate that the proposed algorithm is very competitive with current state-of-the-art approaches.     

Performance of WDM ring and bus networks in the presence ofhomodyne crosstalk

This paper examines the effects of coherent and incoherent homodyne crosstalk in wavelength division multiplexed (WDM) ring and bus networks using reconfigurable optical add-drop multiplexers (OADM's). It is widely understood that incoherent homodyne crosstalk causes power penalties at the receivers in these networks. We show that coherent homodyne crosstalk causes a range of possible received powers, and that coherent and incoherent crosstalk together lead to a range of possible power penalties. A Monte Carlo simulation is used to examine the probability distribution of power penalties due to homodyne crosstalk under various conditions. We find that increasing the switch and multiplexer crosstalk within each OADM, and increasing the number of WDM channels, all produce increased probabilities of large power penalties. However, the number of nodes through which a signal is transmitted does not affect the power penalty distribution     

DIFS: a distributed index for features in sensor networks

Sensor networks pose new challenges in the collection and distribution of data. Recently, much attention has been focused on standing queries that use in-network aggregation of time series data to return data statistics in a communication-efficient manner. In this work, rather than consider searches over time series data, we consider searches over semantically rich high-level events, and present the design, analysis, and numerical simulations of a spatially distributed index that provides for efficient index construction and range searches. The scheme provides for a more balanced sharing of communication load over index nodes by using the governing property that the wider the spatial extent known to an index node, the more constrained is the value range covered by that node.     

On the distribution and performance implications of filteredinterferometric crosstalk in optical WDM networks

The distribution and performance implications of filtered interferometric crosstalk in optical networks is theoretically and experimentally studied. The probability density function is estimated by using a maximum entropy approach based on analytically derived statistical moments. The theoretical results are confirmed by relevant experimental data obtained from an amplitude shift keying direct detection (ASK/DD) system using directly, and externally modulated light sources. Power penalties are measured for both types of source modulation. The experimental results are in good agreement with theory     

工艺变化下互连线分布参数随机建模与延迟分析

随着超大规模集成电路制造进入深亚微米和超深亚微米阶段,电路制造过程中的工艺变化已经成为影响集成电路互连线传输性能的重要因素.文中引入高斯白噪声建立了互连线分布参数的随机模型,并提出基于Elmore延迟度量的工艺变化下的互连延迟估计式;通过简化工艺变化量与互连线参数之间的关系式,对延迟一阶变化量与二阶变化量进行了分析,给出一般工艺变化下互连延迟的统计特性计算方法;另,针对线宽工艺变化推导出互连延迟均值与方差的计算公式.最后通过仿真实验对工艺变化下互连线延迟分析方法及其统计特性计算公式的有效性进行了验证.     

Autonomous and distributed mobility management in mobile core networks

The 5th generation mobile and wireless communication systems are expected to accommodate exploding traffic, increasing number of devices, and heterogeneous applications driven by proliferation of IoT and M2M technologies. However, the centralized mobility management architecture in a current mobile core network would face critical problems such as excessive concentration of load on specific servers and considerable increase in C-plane overhead. To solve the problems we first consider a novel architecture of distributed mobility management in C-plane in the mobile core network, which employs virtualized mobility management entity called ADMMEs (Autonomous Distributed Mobility Management Entity) in this paper. In addition, to assign an appropriate ADMME to a UE in accordance with mobility characteristics of the UE and a management policy, we propose an autonomous and adaptive ADMME selection scheme. We adopt a biologically-inspired algorithm, called attractor selection, to accomplish adaptive selection taking into account multiple objectives. Through simulation experiments, we confirmed our proposal could accomplish more than 63 % performance improvement comparing to the current method from viewpoints of delay, load balancing, and C-plane overhead under a dynamic mobility scenario.     

Task allocation and scheduling in wireless distributed computing networks

Wireless distributed computing (WDC) is an enabling technology that allows radio nodes to cooperate in processing complex computational tasks of an application in a distributed manner. WDC research is being driven by the fact that mobile portable computing devices have limitations in executing complex mobile applications, mainly attributed to their limited resource and functionality. This article focuses on resource allocation in WDC networks, specifically on scheduling and task allocation. In WDC, it is important to schedule communications between the nodes in addition to the allocation of computational tasks to nodes. Communication scheduling and heterogeneity in the operating environment make the WDC resource allocation problem challenging to address. This article presents a task allocation and scheduling algorithm that optimizes both energy consumption and makespan in a heuristic manner. The proposed algorithm uses a comprehensive model of the energy consumption for the execution of tasks and communication between tasks assigned to different radio nodes. The algorithm is tested for three objectives, namely, minimization of makespan, minimization of energy consumption, and minimization of both makespan and energy consumption.