A scalable video-on-demand system using multi-batch buffering techniques

A video-on-demand (VoD) system delivers videos on demand over an installed network. Due to the large size of digitized videos, expensive video servers with high I/O capability are needed in order to provide VoD services in metropolitan areas. In addition, there is a great need for efficient networking distribution/interaction schemes so that the video servers can serve as many clients as possible. In particular, because of scalability problems, the classical unicast VoD system is not suitable for large-scale deployments. In this paper, a highly scalable VoD system with a low per-user cost is described and evaluated. We first analyze the performance degradation problems using recently proposed VoD systems, namely batched and centralized-buffer VoD systems that occur during the handling of interactions. Then a new system called the multi-batch buffer (MBB) system, which attempts to solve these problems, is proposed. The proposed system handles a majority of interaction requests by scalable buffering techniques employed in the buffer of the local servers and the set-top boxes (STB). We have performed extensive simulation for the analysis and performance evaluation of our proposed VoD system. The simulation results demonstrate that our VoD system is very scalable and outperforms related state-of-the-art VoD systems.     

Design of scalable decoders for sensor networks via Bayesian network learning

Minimum mean square error (MMSE) decoding in a large-scale sensor network which employs distributed quantization is considered. Given that the computational complexity of the optimal decoder is exponential in the network size, we present a framework based on Bayesian networks for designing a near-optimal decoder whose complexity is only linear in network size (hence scalable). In this approach, a complexity-constrained factor graph, which approximately represents the prior joint distribution of the sensor outputs, is obtained by constructing an equivalent Bayesian network using the maximum likelihood (ML) criterion. The decoder executes the sum-product algorithm on the simplified factor graph. Our simulation results have shown that the scalable decoders constructed using the proposed approach perform close to optimal, with both Gaussian and non-Gaussian sensor data.     

A scalable agent-based network measurement infrastructure

The rapid growth of computer networks has made the process of understanding the interaction among network components more challenging than ever. The increase in the size of networks is accompanied by the more demanding use of networks by distributed applications that critically rely on the system to function well. Consequently, monitoring the health and stability of networks has become crucial. Tools and probes to measure the performance of networks for the purpose of management, fault diagnosis, or performance evaluation have been developed by several research groups. There is not yet, however, a measurement infrastructure which offers systematic control and management of measurement efforts and performance data focused on supporting distributed network-aware applications. This work addresses the implementation of a scalable and extensible network measurement infrastructure used to capture network state to improve the performance of a distributed application     

A scalable high-performance active network node

Active networking in environments built to support link rates up to several gigabits per second poses many challenges. One such challenge is that the memory bandwidth and individual processing power of the router's microprocessors limit the total available processing power of a router. In this article we identify and describe three components, which promise a high-performance active network solution. This implements the key features typical to active networking, such as automatic protocol deployment and application specific processing, and it is suitable for a gigabit environment. First, we describe the hardware of the active network node (ANN), a scalable high-performance platform based on off-the-shelf CPUs connected to a gigabit ATM switch backplane. Second, we introduce the ANN's modular, extensible, and highly efficient operating system (NodeOS). Third, we describe an execution environment running on top of the NodeOS, which implements a novel large-scale active networking architecture called distributed code caching     

一种新颖的基于神经网络的压力传感器标定系统

根据一种特定的输入-输出特性曲线,本文提出了一种新颖的标定算法,同时设计了一种可有效消除该非线性误差的标校系统。 不同于常规的BP和RBF,本文的方法首先获取该特性曲线的斜率和截距,然后得到电压-压力的特性曲线。测试结果表明：本算法收敛速度快,具有很强的鲁棒性,同时可得到很小的MSE。不同的试验结果也表明：本标校系统工作稳定,测量精度优于设计要求,而且,本系统具有很好的实时性。     

Mobile sensor network programming system

Sensors carried by moving objects in the cities can be used in various applications such as environmental monitoring, traffic control and recreational purposes. A mobile sensor network can be formed by sensors carried by people or buses. In this paper, we will present a mobile sensor network programming system (MSNPS) that can program or reprogram such mobile sensor networks. The programming process is usually initiated by a user from the Internet. MSNPS uses a gateway protocol to bridge the Internet and sensor network, so that control and data messages can be exchanged between these two networks. MSNPS sends the program data to the targeted sensor platforms using a tree structure formed by control messages. We developed a prototype implementation, and analyzed MSNPS system performance. We also simulated the system in a mobile sensor network.     

R-Vivaldi：距离范围感知的IP网络坐标系统

分析发现,对需预测的节点间时延,若选择在该时延范围附近的节点作为锚节点,则能提高该时延预测准确度。基于此,提出了一种距离范围感知的IP网络坐标系统,即R-Vivaldi。其主要思路为:根据需预测的节点间时延的大致取值范围,在与该取值范围相近的一个距离半径的空间内,重新选择锚节点而得到它的一个新取值范围。依照该过程,被预测时延的取值范围更加明晰,并不断地动态调整锚节点的选择,直至节点间时延的预测误差满足一定需要。仿真结果表明,此方案能有效地提高距离预测准确性,而且在一定程度上克服了预测准确度不一致性问题。     

THE PN2I NETWORK： A SCALABLE BANYAN NETWORK

To design a Banyan network with an arbitrary even-sized port number, the PN2I network is proposed. The PN2I network can be divided into two classes： the complete and incomplete versions. A simple routing algorithm is given, but in the incomplete PN2I networks, this routing algorithm fails to make the traffic in links even, which deteriorates the performance badly. Thus a new routing algorithm is proposed, which makes the incomplete PN2I networks behave almost the same as the PN2I networks with respect to the performance issues.     

Monitoring power transmission lines using a wireless sensor network

Power transmission is the bulk transfer of electrical energy from power plants to sub‐stations. A wireless sensor network is a promising technology for transmission line monitoring due to its low cost, easy installation, large‐scale coverage, and fault tolerance characteristics. A wireless sensor network is application‐specific; therefore, we investigate the new features and requirements of the wireless sensor network used in transmission line monitoring. Then, we propose an efficient wireless sensor network framework, which includes a clustering algorithm to simplify network management and to balance the network's energy consumption and a hybrid media access control (MAC) (H‐MAC) protocol to handle traffic variability. The framework takes advantage of the features of network topology and traffic pattern to optimize the protocols' performance on real time and energy efficiency. The results indicate that the H‐MAC shows a significant improvement in the network's reliability, real‐time performance, and energy efficiency, and the cluster hierarchy can balance the network's energy consumption. Furthermore, the cluster hierarchy also prolongs the network's lifetime. Copyright © 2014 John Wiley & Sons, Ltd.     

The scalable lightwave network

In principle, an optical network employing wavelength routing, wavelength reuse, and multihop packet switching is modularly scalable to very large configurations in both the hardware and software sense. As such, it is a viable architecture for a new ATM-based telecommunications infrastructure The network architecture considered for a new, scalable, broadband telecommunications infrastructure is based on (1) the use of wavelength division multiplexing (WDM) and wavelength routing; (2) the translation of signals from one wavelength to another at the access stations; and (3) the use of multihop ATM packet switching. These principles permit networks to be built whose size is essentially unlimited     

Low-cost and scalable passive optical network architecture using remote repeater

We report a new passive optical network (PON) architecture to reduce customer transmitter cost using an upstream repeater at the remote node. The system can further provide both downstream and upstream regeneration by utilising standard bidirectional transceivers. Our architecture can extend a conventional PON's feeder fibre reach to 50 km and split ratio to 1:256. The system demonstration shows insignificant penalty to the existing network performance and meets the IEEE 802.3ah standard requirements.     

A MAC protocol to reduce sensor network energy consumption using a wakeup radio

For increasing the life of sensor networks, each node must conserve energy as much as possible. In this paper, we propose a protocol in which energy is conserved by amortizing the energy cost of communication over multiple packets. In addition, we allow sensors to control the amount of buffered packets since storage space is limited. To achieve this, a two-radio architecture is used which allows a sensor to "wakeup" a neighbor with a busy tone and send its packets for that destination. However, this process is expensive because all neighbors must awake and listen to the primary channel to determine who is the intended destination. Therefore, triggered wakeups on the primary channel are proposed to avoid using the more costly wakeup procedure. We present a protocol for efficiently determining how large the period for these wakeups should be such that energy consumption is reduced.     

An energy-aware forecasting-based framework using a novel moving coordinate scheme for sensor real-time communications

Wireless Networks - In order to save on the energy expended by a sensor node in its communications with the sink, forecasting-based frameworks have recently been proposed. Those frameworks...     

一种面向分布式网络管理的自适应可扩展模型

本文针对大规模分布式网络的特点，提出了一种灵活、动态、自适应伸展性网络管理方案。它采和层次型体系结构，支持多个管理域的分布式网络管理，适应了大规模网络的规模可变性和弹性的特点。为了解决网络事件大量性、多样性和相关性的问题，本文将网络事件分为简单事件和复合事件两种类型，采用层次型事件处理机制和基于动态时间窗的事件合成方法，保证了事件检测的可靠性，平衡了系统负载，降低了网络资源的占有率。     

航空电子传感器系统Powell网络评估方法

航空电子传感器系统是由多个子系统组成的复杂的系统,传统的传感器系统评估方法不适合评估航空电子传感器系统。为此,本文提出了一种基于Powell网络的航空电子传感器系统评估方法。该方法用两个独立的Powell网络对航空电子传感器输出信号进行一步预测,然后将两个预测值和系统输出信号当前实际量测值进行分析评估,并给出航空电子传感器系统的评估结果和系统可靠输出值。仿真实验和某型航空电子系统的实际应用表明:本文提出的传感器系统评估方法可行,并取得了理想的效果。     

A bandwidth scalable OFDM passive optical network for future access network

In order to reduce the cost for delivering the ever increasing broadband services, network providers need to simplify their network architectures and have a better control of the bandwidth. In this article, we propose a simple and cost-effective bandwidth scalable passive optical network (PON) based on orthogonal frequency division multiplexing (BSOFDM-PON). We report performance analysis in terms of the signal-to-noise ratio (SNR), bit-error-rate (BER), and error vector magnitude (EVM) of a PON system accommodating 32 optical network units (ONUs). Our simulations have successfully demonstrated that throughputs of 35.5 and 53.2 Gbps can be achieved using 16 and 64 QAM, respectively, within a total distance ranging from 20 to 30 km. It gives throughputs of 1.10 and 1.66 Gbps per ONU.     

A scalable ATM switching system architecture

The architecture of an asynchronous transfer mode (ATM) switching system for prototype applications is presented. The general concept to upgrade the existing ISDN switch with an ATM module is introduced, and the building blocks of this ATM module are described in detail. Switching of ATM cells is performed in a single application-specific integrated circuit (ASIC). ASICs can be cascaded to form large switching modules. Peripheral modules interface the ATM switch to external transmission systems and perform all ATM-related functions, including means for redundancy of the switching network. The redundancy scheme tolerates single failures without affecting the user information. A switching network architecture is shown to be capable of fulfilling varying demands in terms of the number of ports for ATM switches and cross connects, concentrators, and multiplexers     

URU Plus — a scalable component-based speaker-verification system for BT's 21st century network

Identity security is an issue that affects us all. In many everyday transactions, you have to prove that you are you (URU). BT has already established a market position with the award-winning URU product, that provides identity validation. A major extension to URU is URU Plus. This allows users to verify their identity through the use of speaker-verification technology. Following initial identity validation via URU, users are no longer required to produce documentary evidence for identity verification, but can instead verify themselves using their voice. The URU Plus system is a component integrated into BT's 21st century network authentication capability. It uses state-of-the-art voice verification technology and is accessed via a Web Service API.     

Generating rectangular coordinates in polar coordinate order

This paper proposes a means by which 2D data represented using the rectangular coordinate system can be converted to its equivalent in the polar coordinate system. Taking note that the order in which data becomes available with a polar coordinate measuring device is most unnatural from the point of view of a rectangular coordinate system, this paper presents a simple yet elegant algorithm that generates the points of a rectangular coordinate system in the natural order in which they would be obtained in a polar coordinate system. The algorithm uses only integer arithmetic and a few simple tests. It can quickly identify the grid points between any two angles or the polar coordinate measurements needed to compute rectangular coordinate measurements by interpolation.