Fuzzy Congestion Control and Policing in ATM Networks

1IntroductionASynchronousTransferMode(ATM)isthesuitabletransfermodefortransmissioninnewhighspeediniCgratedservicenetWorks.Itpossessestheflexibilityneededtosupportserviceswithdifferentrates,qualitiesofservices(QoS)andcharacteristics.TheStatisticalmult...     

Efficient Transmission of MPEG-2 Coded Video Traffic over ATM Networks

Video traffic is expected to account for a significant share of the traffic volume in the future asynchronous transfer mode (ATM) networks. MPEG-2 proposed by Moving Picture Expert Group is one of the most promising compression techniques for such applications. One of the critical issues in MPEG-2 is to realize effective variable bit rate (VBR) video transfer thorough ATM networks. The Leaky Bucket (LB) scheme has been widely accepted as the usage parameter control (UPC) mechanism to police the VBR sources. We proposed a new Adaptive Dynamic Leaky Bucket (ADLB) congestion control mechanism, which is based on the LB scheme. Unlike the conventional LB, the leak rate of the ADLB is controlled using delayed feedback information of available bandwidth sent by the network. This scheme allows sources to get varying amounts of bandwidth over time, while reserving a minimum guaranteed bandwidth (MCR) for the entire duration of the connection. At the time of congestion, the leak rate of the ADLB is adjusted according to the feedback indicating the currently available bandwidth to the connection. The simulation results show that the end-to-end cell transfer delay and cell loss of each source has been improved significantly.     

一种智能监管方法性能的研究

本文提出了改进的模糊漏桶,用于对ＡＴＭ网络业务进行监管,对ＯＮ／ＯＦＦ业务及ＶＢＲ（ＶａｒａｂｌｅＢｉｔＲａｔｅ）视频ＡＲ（一阶ＡｕｔｏＲｅｇｒｅｓｓｉｖｅ模型）业务的仿真结果表明改进模糊漏桶对业务的监管能力要好于漏桶,即监管违约业务响应快,幅度大,并且合法业务对改进模糊漏桶的计资源要求少。     

ATM网络中漏桶流量控制特性的研究

本文对ＡＴＭ（异步转移模式）网络中话音、数据和图像业务的漏桶流量控制特性进行了研究。计算机模拟结果表明，由于各种业务内在的相关性不同，相应的漏桶流量控制特性有较大的差异。漏桶参数的选择对于各种业务具有不同的公平性，因而应根据业务的特性来设计漏桶参数。     

Dynamic versus Static Traffic Policing: A New Approach for Videoconference Traffic over Wireless Cellular Networks

The subject of traffic policing for computer communication networks has been studied extensively in the literature. However, the constant development of new multimedia applications which are ldquogreedyrdquo in terms of bandwidth and Quality of Service requirements calls for new approaches to the traffic policing problem. In this work, we introduce a new video model for single H.263 videoconference sources and we use it in order to propose a new traffic policing approach for wireless videoconference traffic. We study well-known traffic policing mechanisms which still present interesting, unsolved problems when servicing video traffic and propose, to the best of our knowledge, for the first time in the relevant literature that the token generator is based on a traffic model and not on a fixed rate. The proposed approach shows significant improvement in the results obtained by all the traffic policing mechanisms, and hence, shows that dynamic traffic policing can provide much higher efficiency than the widely used static approach.     

ATM网络双速漏桶监管算法

本文提出一种ＡＴＭ网络监管新算法———双速漏桶算法。对它的性能进行理论分析和计算机模拟，并探讨其硬件实现的可能性和复杂性。结果表明：在硬件复杂性基本不增加情况下，双速漏桶监管法比单速漏桶算法在监管选择性、信元丢失率及信元等待时间等性能方面有较大改善。     

帧中继网络的一种拥塞控制机制

本文介绍一帧中继网络的拥塞控制机制－输入速率控制机制。它采用漏桶算法调节从源节点到网络节点的数据流量。本文着重介绍了该输入速度控制机制的实现并作了性能分析。依据帧中继子网的拓扩结构，进行理论分析和计算机模拟，给出了不同参数下的各项性能曲线。     

Weak variable-length Slepian-Wolf coding with linked encoders for mixed sources

Coding problems for correlated information sources were first investigated by Slepian and Wolf. They considered the data compression system, called the SW system, where two sequences emitted from correlated sources are separately encoded to codewords, and sent to a single decoder which has to output the original sequence pairs with a small probability or error. In this paper, we investigate the coding problem of a modified SW system allowing two encoders to communicate with zero rate. First, we consider the fixed-length coding and clarify that the admissible rate region for general sources is equal to that of the original SW system. Next, we investigate the variable-length coding having the asymptotically vanishing probability of error. We clarify the admissible rate region for mixed sources characterized by two ergodic sources and show that this region is strictly wider than that for fixed-length codes. Further, we investigate the universal coding problem for memoryless sources in the system and show that the SW system with linked encoders has much more flexibility than the original SW system.     

A multifractual traffic policing mechanism

In this letter we Introduce a new traffic policing mechanism able to deal with multifractal sources. The ability of monitoring accurately a traffic flow is of extreme importance to avoid malicious behavior on the part of some users and to guarantee the required quality of service of other users. The proposed policing mechanism approximates an ideal algorithm.     

Visualization of Ethereum P2P network topology and peer properties

Ethereum is arguably the second most popular cryptocurrency-based network after Bitcoin. Both use the distributed ledger technology known as the blockchain, which is considered secure. However, the provided security level is proportional to the number of connected nodes, the number of influential nodes, and the supported amount of hash power. Thus, the knowledge of the network properties and nodes' behavior is helpful to protect the network from possible attacks such as double-spending attacks, DDoS attacks, 51% attacks, and Sybil attacks. This paper proposes a node discovery mechanism, which performs a P2P link discovery on the Ethereum main network. For that, we develop Search-node, a modified version of Ethereum client that searches for all participating nodes in the blockchain network, stores the node information in the Bucket, and then processes the peer discovery method. Based on the collected data, we first visualize the Ethereum network topology and analyze the attributes of the network such as node degree, path length, diameter, and clustering coefficient. We then analyze the node properties and provide analytical results regarding the relationship between nodes, heavily connected nodes, node geo-distribution, security issues, and possible attacks over the influential nodes. As a result, we have identified 68,406 nodes with a total of 642,034 edges. By analyzing the collected data, we have found that the diameter in the Ethereum network is equal to 8. The node degree is over 19, which is two times higher than the default configuration.     

Lowpass traffic policing mechanism based on the leaky bucket

A traffic throttle can be modelled as a gate with one input and two outputs: pass for accepted calls, and gap for rejected calls. The gate decides whether to pass or to gap an incoming call according to its policing mechanism. The authors show that a small modification to a leaky bucket policing mechanism yields a lowpass filter. The proposed mechanism is a new type of a nonlinear filter     

Source localization using recursively applied and projected (RAP)MUSIC

A new method for source localization is described that is based on a modification of the well-known MUSIC algorithm. In classical MUSIC, the array manifold vector is projected onto an estimate of the signal subspace. Errors in the estimate of the signal subspace can make localization of multiple sources difficult. Recursively applied and projected (RAP) MUSIC uses each successively located source to form an intermediate array gain matrix and projects both the array manifold and the signal subspace estimate into its orthogonal complement. The MUSIC projection to find the next source is then performed in this reduced subspace. Special assumptions about the array manifold structure, such as Vandermonde or shift invariance, are not required. Using the metric of principal angles, we describe a general form of the RAP-MUSIC algorithm for the case of diversely polarized sources. Through a uniform linear array simulation with two highly correlated sources, we demonstrate the improved Monte Carlo error performance of RAP-MUSIC relative to MUSIC and two other sequential subspace methods: S and IES-MUSIC. We then demonstrate the more general utility of this algorithm for multidimensional array manifolds in a magnetoencephalography (MEG) source localization simulation     

The potential performance gain in using spectral information inpassive detection/localization of wideband sources

We address the problem of detecting the presence of wideband point sources and/or estimating their location using data collected by an array of sensors. This passive localization problem is typical to applications where the radiated signals do not carry information and are of no interest. However, knowledge of their waveshape, or their cross spectral matrix, is essential for applying optimal/sub-optimal detection/localization algorithms. In this paper, we present results of a study in which we compare the optimal procedures for detection/localization and their performance to suboptimal procedures that use no spectral information or only partial spectral information. We show that if the number of sensors in the array is larger than the number of sources to be localized (or detected), then the performance gain of the optimal procedures is potentially significant mainly in conditions of small separation and/or high correlation between sources. The performance gain is also a function of the spectrum: it is potentially higher if the sources are known to be correlated and if their spectra is not smooth. If, however, the number of sources is smaller than the number of sensors, then the role of the spectral information in improving detection/localization performance becomes major: only the use of spectral prior enables reliable localization of more sources than sensors     

Buffered and Unbuffered Leaky Bucket Policing: Guaranteeing QoS,Design and Admission Control

Traffic shaping and smoothing using buffers or leaky buckets does not necessarily improve Quality of Service (QoS). In fact there is a trade-off between controlling user traffic and guaranteeing QoS to the users. We consider the first two stages (source node and border node before entering a network cloud) of an end-to-end QoS problem and assume that the QoS requirements across each of the two stages are given. We formulate and solve a mathematical programming problem to select optimal leaky bucket parameters that would enable high-speed telecommunication network providers to optimize traffic policing subject to guaranteeing a negotiated Quality of Service requirement across the first stage namely the source end. We address both the buffered and unbuffered leaky bucket cases where using fluid models we characterize the output process from the leaky buckets for general traffic sources. Using the optimal leaky bucket parameters and output characteristics (effective bandwidths in particular), we solve design and connection admission control problems given QoS requirements at the second stage, namely the border node.     

Efficient Optimization of Reference-Based Negentropy for Noncircular Sources in Complex ICA

Bingham proposed a complex fast independent component analysis (c-FastICA) algorithm to approximate the nengentropy of circular sources using nonlinear functions. Novey proposed extending the work of Bingham using information from a pseudo-covariance matrix for noncircular sources, particularly for sub-Gaussian noncircular signals such as binary phase-shift keying signals. Based on this work, in the present paper we propose a new reference-based contrast function by introducing reference signals into the negentropy, upon which an efficient optimization FastICA algorithm is derived for noncircular sources. This new approach is similar to Novey’s nc-FastICA algorithm, but differs in that it is much more efficient in terms of the computational speed, which is significantly notable with a large number of samples. In this study, the local stability of our reference-based negentropy is analyzed and the derivation of our new algorithm is described in detail. Simulations conducted to demonstrate the performance and effectiveness of our method are also described.     

Analysis of the convergence properties of self-normalized sourceseparation neural networks

An extended source separation neural network was derived by Cichocki et al. (see Proc. 1995 Int. Symp. Nonlinear Theory Appl. NOLTA, Las Vegas, NV, p.61-65, 1995) from the classical Herault-Jutten network. It claimed to have several advantages, but its convergence properties were not described. In this paper, we first consider the standard version of this network. We determine all its equilibrium points and analyze their stability for a small adaptation gain. We prove that the stationary independent sources that this network can separate are the globally sub-Gaussian signals. As the Herault-Jutten (1991) network applies to the same sources, we thus show that the advantages of the new network are not counterbalanced by a reduced field of application, which confirms its attractiveness in the considered conditions. Moreover, we then introduce and analyze a modified version of this network, which can separate the globally super-Gaussian source signals. These theoretical results are experimentally confirmed by computer simulations. As a result of our overall investigation, a method for processing each one of the two classes of signals (i.e. sub- and super-Gaussian) is available     

On refocusing a radio telescope to image sources in the near fieldof the antenna array

A theoretical model is developed for describing the operation of a radio telescope using techniques from optical coherence theory. This model is then used to develop a more systematic approach to the problem of refocusing a radio telescope to image sources which are within the near-field of the antenna array when the antenna array is in the far field of the source distribution. This is done by refocusing the telescope onto the sources in analogy to a photographic camera. Two methods for refocusing the telescope are described which would require no modification to most existing telescopes. In the first method, refocusing is accomplished either electronically by curving the antenna array into a portion of a hemisphere with a center at the source, or, alternatively by processing the correlation function data obtained from the antennas in a somewhat modified manner     

How to encode the modulo-two sum of binary sources (Corresp.)

How much separate information about two random binary sequences is needed in order to tell with small probability of error in which positions the two sequences differ? If the sequences are the outputs of two correlated memoryless binary sources, then in some cases the rate of this information may be substantially less than the joint entropy of the two sources. This result is implied by the solution of the source coding problem with two separately encoded side information sources for a special class of source distributions.     

ATM Interface Technologies for an ATM Switching System

Realization of the economical, reliable, and efficient ATM interface block becomes an important key to development of the ATM switching system when we consider new issues raised recently. In this paper, we summarize requirements for the ATM interface block and present the UNI (User Network Interface)/NNI (Network Node Interface) architecture to meet these requirements. We also evaluate the performance of the multiplexer adopting the various multiplexing schemes and service disciplines. For ATM UNI/NNI interface technologies, we have developed a new policing device using the priority encoding scheme. It can reduce the decision time for policing significantly. We have also designed a new spacer that can space out the clumped cell stream almost perfectly. This algorithm guarantees more than 99 % conformance to the negotiated peak cell rate. Finally, we propose the interface architecture for accommodation of the ABR (Available Bit Rate) transfer capability. The proposed structure that performs virtual source and virtual destination functions as well as a switch algorithm can efficiently accommodate the ABR service.