A Generic Framework for Mobility Modeling and Performance Analysis in Next-Generation Heterogeneous Wireless Networks

Integration of different wireless radio cellular technologies is emerging as an effective approach to accommodate the increasing demand of next-generation multimedia-based applications. In such systems user roaming among different technologies, commonly known as vertical handoff, will significantly affect different aspects of network design and planning due to the characteristically wide-ranging diversity in access technologies and supported applications. Hence, the development of new mobility models that accurately depict vertical mobility is crucial for studying different design problems in these heterogeneous systems. This article presents a generic framework for mobility modeling and performance analysis of integrated heterogeneous networks using phase-type distributions. This framework realizes all modeling requirements in next-generation user mobility including accuracy, analytical tractability, and accommodating the correlation between different residence times within different access technologies. Additionally, we present general guidelines to evaluate application performance based on the new mobility models introduced in this article. We show the accuracy of our modeling approach through simulation and analysis given different applications.     

A Generic Framework for Cross-Layer Optimisation in Wireless Personal Area Networks

Wireless Personal Area Networking (WPAN) is introduced as a new concept for next generation wireless systems. WPANs are short-range wireless systems operating in the direct surrounding of the user. A reference architecture for short-range wireless communications has been designed covering the end-to-end system design. Traditional protocol stack implementations based on layering do not function efficiently in wireless environments due to inefficiency, inflexibility and suboptimality of the functionalities in the different layers. Specifically in WPAN and other short-range wireless systems the performance benefits from a cross-layer design strategy, supporting adaptability and optimizing the use of resources over multiple layers of the protocol stack. In this paper we advocate cross-layer optimisation for WPAN systems and introduce a centralised control structure for interaction between different layers in master or leader devices. The control structure adapts the link characteristics to the channel state and user requirements. Allowing for the support of heterogeneous services, each with their own quality-of-service demands, in wireless environments.     

基于数据交互平台进行“信息孤岛”消除法研究

结合分析我国电子制造业向网络制造、虚拟制造、异地协同设计、多学科优化设计发展整合的趋势,研究提出如何利用Oracle透明网关、中间件技术与SOA架构和企业服务总线,构建统一的、规范的数据交互平台。建立不同业务信息系统之间的数据关系,实现标准统一的数据服务,解决不同异构系统之间的数据同源、数据交互、信息互联互通和数据共享等问题,消除信息化建设中产生的“信息孤岛”现象。为后续开展信息交互标准研究工作打下基础。     

Anyhow, anywhere: the rise of open distributed processing

In the next revolution in computing, programmers will continue to program to a virtual machine, but behind this unitary programming interface will lie, not a single computer, but multiple computers at various locations, with different machine architectures, different operating systems and running code in a multiplicity of programming languages. The umbrella name for this new era of computational freedom is open distributed processing, or ODP. ODP will radically enhance the capacity to design and operate complex systems comprising many physically distributed, heterogeneous computers. The author discusses the architecture of ODP as developed by the Advanced Network Systems Architecture project, ANSAware, a toolkit for ODP system development, and ODP standards     

Robust Rate Control for Heterogeneous Network Access in Multihomed Environments

We investigate a novel robust flow control framework for heterogeneous network access by devices with multi-homing capabilities. Towards this end, we develop an H-infinity-optimal control formulation for allocating rates to devices on multiple access networks with heterogeneous time-varying characteristics. H-infinity analysis and design allow for the coupling between different devices to be relaxed by treating the dynamics for each device as independent of the others. Thus, the distributed end-to-end rate control scheme proposed in this work relies on minimum information and achieves fair and robust rate allocation for the devices. An efficient utilization of the access networks is established through an equilibrium analysis in the static case. We perform measurement tests to collect traces of the available bandwidth on various WLANs and Ethernet. Through simulations, our approach is compared with AIMD and LQG schemes. In addition, the efficiency, fairness, and robustness of the H-infinity-optimal rate controller developed are demonstrated via simulations using the measured real world network characteristics. Its favorable characteristics and general nature indicate applicability of this framework to a variety of networked systems for flow control.     

A survey of mobility management in next-generation all-IP-based wireless systems

Next-generation wireless systems are envisioned to have an IP-based infrastructure with the support of heterogeneous access technologies. One of the research challenges for next generation all-IP-based wireless systems is the design of intelligent mobility management techniques that take advantage of IP-based technologies to achieve global roaming among various access technologies. Next-generation wireless systems call for the integration and interoperation of mobility management techniques in heterogeneous networks. In this article the current state of the art for mobility management in next-generation all-IP-based wireless systems is presented. The previously proposed solutions based on different layers are reviewed, and their qualitative comparisons are given. A new wireless network architecture for mobility management is introduced, and related open research issues are discussed in detail.     

电子政务系统整合研究

信息技术的应用多样性、复杂性与计算分布性,导致许多应用系统基于分布式网络由多种异构资源组成。对电子政务的各组成部门而言,各自的信息系统存在着不同时期、由不同开发商、利用不同的开发工具、在不同的开发平台上搭建起来。这就给以后的整合关联应用带来不便。为了保障数据的一致性、提高数据的共享性,就需要建立一个横跨多种异构系统的数据交换平台。文中从多个信息系统的整合需求出发,经研究分析,提出了针对性的技术解决方案。     

An automated parallel simulation flow for cyber-physical system design

Parallel and distributed simulation (PDS) is often employed to tackle the computational intensity of system-level simulation of real-world complex embedded and cyber-physical systems (CPSs). However, CPS models comprise heterogeneous components with diverge semantics for which incompatible PDS approaches are developed. We propose an automated PDS flow based on a formal modeling framework—with necessary extensions—targeting heterogeneous embedded and CPS design. The proposed flow characterizes the sequential executable specification of a heterogeneous model and generates a PDS cluster. State-of-the-art graph partitioning methods are adopted and a new extensible constraint-base formulation of the model partitioning problem is developed. The applicability, effectiveness, and scalability of the proposed flow is demonstrated using case studies.     

Bio-inspired Porous Composite Electrode for Enhanced Mass Transfer and Electrochemical Water Purification by Modifying Local Flow Pattern

Porous electrodes offer a new opportunity for flow-through electrochemical water purification, but their irregular porous-structure makes the local flow pattern and mass transfer performance inhomogeneous, unpredictable, and uncontrollable. In this study, a bio-inspired design is reported for porous electrode by learning the micro-scale architectures of the wings of butterfly and owl based on analogy between heterogeneous mass transfer and sound absorption. Results demonstrate that combining gyroid and perforated plate can produce strong periodic vortex and inertial flow in interpenetrating channels even at laminar flow region. This enables homogeneous, predictable and controllable flow patterns and enhanced mass transfer, which can be explained by uniformity analysis and physical field synergy. Based on experimental tests on Cu electrode fabricated by selective laser melting, the composite gyroid electrode generates the limiting current density of 83% higher than random porous-structured electrode, accounting for nitrate removal as high as 95% by electrochemical denitrification. This study represents a paradigm shift to advance design for porous architectures by learning experiences of hydrodynamic behaviors from nature. In this way, it is feasible to enhance mass transfer by modifying local flow patterns on pore scale, which may have broader implications that extend to other heterogeneous reaction systems.     

Multidimensional DSP Core Synthesis for FPGA

Current rapid synthesis approaches for reusable dedicated hardware components (cores) for digital signal processing systems are ineffective since they fail to capture and exploit the manner in which the resulting components are used as part of a heterogeneous system. This leads to counter-productive core redesign for each use of the core. This paper presents a solution to this issue which combines a novel but intuitive system modeling technique and associated core generation and integration methodology which generates reuable core architectures which may be optimised via algorithm level transformations. For an example design problem, these provide an effective rapid core synthesis and implementation exploration flow which allows a factor 3.9 throughput increase with no extra hardware expense. John McAllister received a first honours B.Eng degree in Electrical and Electronic Engineering and the degree of PhD from Queen’s University Belfast, UK in 2001 and 2004 respectively.From October 2004 to July 2005 he was a Postdoctoral Research Assistant in the Programmable Systems Laboratory in the System on Chip research group in the Institute for Electronics, Communication and Information Technology (ECIT) at Queen’s University Belfast.In July 2005 he was appointed to a lectureship in SoC technology in the International Centre for System-on-Chip and Advanced Microwireless (SoCAM) project at ECIT. Roger Woods received the degree of B.Sc with Honours in Electrical and Electronic Engineering and degree of Ph.D. from the Queen’s University of Belfast, UK in 1985 and 1990 respectively. From 2003, he has been a Professor at the same university and leads the programmable systems and networks laboratory there. His main research interests are programmable hardware systems using FPGAs, design tools for heterogeneous platforms and low power VLSI. He has published over 120 papers in the area of VLSI and DSP, holds two patents and serves on numerous technical program committees including Workshop on Signal Processing Systems, Field Programmable Logic and Field Programmable Technology. He is a member the IEEE Signal Processing Society Technical Committee for the Design and Implementation of Signal Processing Systems and chair of the IEE Professional Network on Microelectronics and Embedded Systems. Richard Walke received his Ph.D. from Warwick University in 1998 for work on arithmetic, architectures and implementations of adaptive weight calculation in ASIC. Subsequently he worked on the implementation of a range of DSP algorithms in FPGA, specialising in floating-point arithmetic, digital receivers and adaptive beamformers on FPGA. In recent years he has lead work to address the design of heterogeneous systems employing both processor and FPGA. Last year he moved to Xilinx, and is now responsible for the development of their floating-point IP solution. Darren Reilly received first honours B.Eng. Degree in Electronic and Software Engineering from the Queen’s University Belfast in 2002. He is currently pursuing a Ph.D. in Queen’s University Belfast due to finish in September 2005. His research interests lie in the rapid development of efficient architectures for FPGA as part of a system level design flow.     

SPI - a system model for heterogeneously specified embedded systems

Embedded systems typically include reactive and transformative functions, often described in different languages and semantics which are well established in their respective application domains. Additionally, a large part of the system functionality and components is reused from previous designs including legacy code. There is little hope that a single language will replace this heterogeneous set of languages. A design process must be able to bridge the semantic differences for verification and synthesis and should account for limited knowledge of system properties. This paper presents the system property intervals (SPI) model, which employs behavioral intervals and process modes to allow the common representation of different languages and semantics. This model is the basis of a workbench which is targeted at the design of heterogeneously specified embedded systems.     

Traffic scheduling in a photonic packet switching system with QoSguarantee

The main challenge in the design of future broadband networks is to efficiently support high-bandwidth multimedia services. Recent advances in the optical networking reveal that all optical networks offering multigigabit rate per wavelength may soon become economical as the underlying backbone in wide area networks, in which photonic switch plays a central role. Two issues are the essential in the design of photonic packet switching, the support of end-to-end virtual connections and the support of diverse quality-of-service (QoS) services. Existing work in wide-area optical networks has largely focused on the former, relatively less attention has been given to support heterogeneous traffic types and to satisfy the potentially different QoS requirements of different types of traffic. In this paper, we introduce a novel hierarchical scheduling framework to use in a class of photonic packet switching systems based on WDM, in which we separate the flow scheduling from the transmission scheduling. We show such separation is essential for achieving scalability such that large input-output ports can be accommodated, and also for offering flexibility in that optimal scheduling algorithms can be derived in different level that can be best tuned to the specific system requirements. The salient feature of the proposed scheduling mechanism is that it takes into account potentially different QoS requirements from different traffic flows. A number of interesting findings are observed from the results obtained by both analysis and simulation: (1) QoS requirements can be satisfied for both real-time and nonreal-time flows; (2) the impact Of the real-time traffic head-of-line (HoL) blocking on the system throughput can be effectively alleviated with the prevailing number of traffic flows. In addition, we investigate a variety of performance measures under different system configurations     

Heterogeneous Simulation—Mixing Discrete-Event Models with Dataflow

This paper relates to system-level design of signal processing systems, which are often heterogeneous in implementation technologies and design styles. The heterogeneous approach, by combining small, specialized models of computation, achieves generality and also lends itself to automatic synthesis and formal verification. Key to the heterogeneous approach is to define interaction semantics that resolve the ambiguities when different models of computation are brought together. For this purpose, we introduce a tagged signal model as a formal framework within which the models of computation can be precisely described and unambiguously differentiated, and their interactions can be understood. In this paper, we will focus on the interaction between dataflow models, which have partially ordered events, and discrete-event models, with their notion of time that usually defines a total order of events. A variety of interaction semantics, mainly in handling the different notions of time in the two models, are explored to illustrate the subtleties involved. An implementation based on the Ptolemy system from U.C. Berkeley is described and critiqued.     

An overview of configurable computing machines for software radio handsets

The advent of software radios has brought a paradigm shift to radio design. A multimode handset with dynamic reconfigurability has the promise of integrated services and global roaming capabilities. However, most of the work to date has been focused on software radio base stations, which do not have as tight constraints on area and power as handsets. Base station software radio technology progressed dramatically with advances in system design, adaptive modulation and coding techniques, reconfigurable hardware, A/D converters, RF design, and rapid prototyping systems, and has helped bring software radio handsets a step closer to reality. However, supporting multimode radios on a small handset still remains a design challenge. A configurable computing machine, which is an optimized FPGA with application-specific capabilities, show promise for software radio handsets in optimizing hardware implementations for heterogeneous systems. In this article contemporary CCM architectures that allow dynamic hardware reconfiguration with maximum flexibility are reviewed and assessed. This is followed by design recommendations for CCM architectures for use in software radio handsets.