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A Novel Fairness-Aware Resource Allocation Scheme in Multiuser SISO-OFDMA Downlink 一种新的多用户sso - ofdma下行链路公平感知资源分配方案
Pub Date : 2010-08-30 DOI: 10.1155/2010/432762
Vasileios D. Papoutsis, I. Fraimis, S. Kotsopoulos
The problem of resource allocation for the downlink of wireless systems operating over a frequency-selective channel is investigated. It is assumed that both the Base Station (BS) and each user are equipped with a single antenna (Single Input Single Output-SISO case), and Orthogonal Frequency Division Multiple Access (OFDMA) is used as a multiple access scheme. The aim is to maximize the sum of the users' data rates subject to constraints on total available power and proportional fairness among users' data rates. Achieving the optimal solution has a high computational cost thereby the use of suboptimal techniques is necessary. A suboptimal, but efficient, scheme is devised, and it is shown, via simulation, that not only the proposed resource allocation scheme achieve higher sum of the users' data rates than other existing schemes but also the sum data rate is distributed fairly and flexibly among users. In addition, the proposed scheme is complexity effective and can be applied to latest-generation wireless systems that provide Quality-of-Service (QoS) guarantees.
研究了在频率选择信道上运行的无线系统下行链路的资源分配问题。假设基站(BS)和每个用户都配备了单天线(single Input single Output-SISO),并采用正交频分多址(OFDMA)作为多址方案。目标是在总可用功率和用户数据速率之间的比例公平约束下最大化用户数据速率的总和。实现最优解具有很高的计算成本,因此使用次优技术是必要的。设计了一种次优但高效的资源分配方案,仿真结果表明,所提出的资源分配方案不仅实现了比现有方案更高的用户数据速率总和,而且数据速率总和在用户之间的分配公平灵活。此外,该方案具有复杂性有效性,可应用于提供服务质量(QoS)保证的最新一代无线系统。
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引用次数: 9
Aspect of Dynamic Simulation and Experimental Research Studies on Hybrid Pneumatic Power System 混合动力气动动力系统动态仿真与实验研究
Pub Date : 2010-06-23 DOI: 10.1155/2010/893197
K. D. Huang, H. Nguyễn
A Hybrid Pneumatic Power System (HPPS) has been developed for several years with the major aim of reducing the vehicle fuel consumption, environment pollution and enhancing the vehicle performance as well. Comparing with the conventional hybrid system, HPPS replaces the battery's electrochemical energy with a high-pressure air storage tank and enables the internal combustion engine (ICE) to function at its sweet spot. Besides, the HPPS, which effectively merges both the high-pressure air flow from the storage tank and the recycled exhaust flow from the ICE, thereby increases the thermal efficiency of the ICE and transforms the merged flow energy into mechanical energy using a high-efficiency turbine. This paper focuses on the major research process into HPPSs, including overall dynamic simulation and experimental validation. By using the simulation tool ITI-Sim, this research demonstrates an experiment which can be operated precisely according to the requirements of various driving conditions under which a car actually runs on the road in accordance with the regulated running vehicle test mode. HPPS is expected to increase the performance of the entire system from 15% to 39%, and is likely to replace the traditional system in the coming years.
混合动力气动动力系统(HPPS)是近年来发展起来的一种新型动力系统,其主要目的是降低汽车燃油消耗、降低环境污染、提高汽车性能。与传统的混合动力系统相比,HPPS用高压储气罐取代了电池的电化学能量,使内燃机(ICE)能够在最佳位置工作。此外,HPPS有效地融合了来自储气罐的高压气流和来自ICE的回收废气流,从而提高了ICE的热效率,并通过高效涡轮将合并的流能转化为机械能。本文重点介绍了hpps的主要研究过程,包括总体动态仿真和实验验证。本研究利用仿真工具ti - sim,根据汽车实际在道路上行驶的各种行驶条件的要求,按照规定的行驶车辆试验模式,进行了一项可以精确操作的实验。HPPS有望将整个系统的性能从15%提高到39%,并有可能在未来几年内取代传统系统。
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引用次数: 0
Managing DSRC and WAVE Standards Operations in a V2V Scenario 在V2V场景中管理DSRC和WAVE标准操作
Pub Date : 2010-06-20 DOI: 10.1155/2010/797405
Y. Morgan
The Dedicated Short-Range Communications (DSRC) standards suite is based on multiple cooperating standards mainly developed by the IEEE. In particular, we focus this paper on the core design aspects of DSRC which is called Wireless Access in Vehicular Environment (WAVE). WAVE is highlighted in IEEE 1609.1/.2/.3/.4. The DSRC and WAVE standards have been the center of major attention in both research and industrial communities. In 2008, WAVE standard was the third best seller standards in the history of the IEEE. This attention reflects the potential of WAVE to facilitate much of the vehicular safety applications. In this paper we present a fairly detailed tutorial of the WAVE standards. We extend the paper by describing some of the lessons learned from particular design approaches. We direct the reader to the landmark research papers in relevant topics. We alert the reader about major open research issues that might lead to future contribution to the WAVE design.
专用短程通信(DSRC)标准套件是基于IEEE主要制定的多个协作标准。本文特别关注DSRC的核心设计方面,即车载环境中的无线接入(WAVE)。WAVE在IEEE 1609.1/ 0.2 /.3/.4中得到强调。DSRC和WAVE标准一直是研究界和工业界关注的焦点。2008年,WAVE标准是IEEE历史上第三大畅销标准。这种关注反映了WAVE在促进许多车辆安全应用方面的潜力。在本文中,我们提供了一个相当详细的WAVE标准教程。我们通过描述从特定设计方法中学到的一些经验教训来扩展本文。我们引导读者到相关主题的里程碑式的研究论文。我们提醒读者注意可能导致未来对WAVE设计做出贡献的主要开放研究问题。
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引用次数: 14
Suboptimal Rate Adaptive Resource Allocation for Downlink OFDMA Systems 下行OFDMA系统的次优速率自适应资源分配
Pub Date : 2009-08-18 DOI: 10.1155/2009/891367
Sanam Sadr, A. Anpalagan, K. Raahemifar
This paper aims to study the performance of low complexity adaptive resource allocation in the downlink of OFDMA systems with fixed or variable rate requirements (with fairness consideration). Two suboptimal resource allocation algorithms are proposed using the simplifying assumption of transmit power over the entire bandwidth. The objective of the first algorithm is to maximize the total throughput while maintaining rate proportionality among the users. The proposed suboptimal algorithm prioritizes the user with the highest sensitivity to the subcarrier allocation, and the variance over the subchannel gains is used to define the sensitivity of each user. The second algorithm concerns rate adaptive resource allocation in multiuser systems with fixed rate constraints. We propose a suboptimal joint subchannel and power allocation algorithm which prioritizes the users with the highest required data rates. The main feature of this algorithm is its low complexity while achieving the rate requirements.
本文旨在研究具有固定或可变速率要求的OFDMA系统下行链路低复杂度自适应资源分配的性能(考虑公平性)。利用整个带宽上发射功率的简化假设,提出了两种次优资源分配算法。第一种算法的目标是最大化总吞吐量,同时保持用户之间的速率比例。提出的次优算法优先考虑对子载波分配最敏感的用户,并使用子信道增益的方差来定义每个用户的灵敏度。第二种算法关注固定速率约束下多用户系统中的速率自适应资源分配。我们提出了一种次优联合子信道和功率分配算法,该算法优先考虑数据速率要求最高的用户。该算法的主要特点是在满足速率要求的同时具有较低的复杂度。
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引用次数: 32
Priority-Based Inter-Vehicle Communication for Highway Safety Messaging Using IEEE 802.11e 基于ieee802.11 e的基于优先级的公路安全消息传输的车辆间通信
Pub Date : 2009-07-12 DOI: 10.1155/2009/423141
Chakkaphong Suthaputchakun
We propose to use IEEE 802.11e in conjunction with retransmission mechanisms for priority-based Intervehicle Communication (IVC) for highway safety messaging in both vehicular infrastructure and ad hoc networks. Each IVC message, which is assigned a priority based on the safety event urgency, requires different quality of service in terms of communication reliability and average delay. To increase the communication reliability in a broadcast-based IVC, we apply retransmission mechanisms that can provide proportional reliability differentiation for each prioritized message. We evaluate the performance of our proposed protocol using OPNET Modeler, in terms of percentage of successful transmissions and average delay. The protocol performance is evaluated for (1) different system parameters such as the packet size, number of vehicles, and percentage of priority 1 vehicles, and (2) priority-based protocol parameters, such as contention window, interframe spacing and retransmission parameters. The results show that proper protocol parameter settings per priority message result in an efficient solution for priority based broadcast IVC. Moreover, the proposed protocol is fully compatible with both IEEE 802.11 and IEEE 802.11e standards.
我们建议将IEEE 802.11e与重传机制结合使用,用于基于优先级的车辆间通信(IVC),用于车辆基础设施和自组织网络中的高速公路安全消息传递。每个IVC消息根据安全事件的紧急程度被分配优先级,在通信可靠性和平均延迟方面要求不同的服务质量。为了提高基于广播的IVC中的通信可靠性,我们应用了能够为每个优先消息提供比例可靠性区分的重传机制。我们使用OPNET Modeler根据成功传输的百分比和平均延迟来评估我们提出的协议的性能。协议性能是根据(1)不同的系统参数(如数据包大小、车辆数量和优先级为1的车辆的百分比)和(2)基于优先级的协议参数(如竞争窗口、帧间间隔和重传参数)来评估的。结果表明,对每个优先级消息进行适当的协议参数设置可以有效地解决基于优先级的广播IVC问题。此外,该协议完全兼容IEEE 802.11和IEEE 802.11e标准。
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引用次数: 15
Evaluation of Physical Carrier Sense Based Backbone Maintenance in Mobile Ad Hoc Networks 基于物理载波感知的移动自组网骨干网维护评估
Pub Date : 2009-07-05 DOI: 10.1155/2009/958056
Sapna Deval, L. Ritchie, M. Reisslein, A. Richa
Physical carrier sensing has to date mainly been exploited for improving medium access control in wireless networks. Recently, a parallel algorithm striving to extensively exploit physical carrier sensing for constructing and maintaining a connected dominating set (CDS), which is also known as spanner, backbone, or overlay network in wireless ad hoc networks with interference ranges larger than transmission ranges has been proposed. Existing evaluations of this algorithm are limited to theoretical asymptotic bounds and simulations of static networks. In this paper, we evaluate the physical carrier sensing-based CDS maintenance for mobile ad hoc networks through discrete event simulations. For a wide range of node speeds and node densities, we evaluate the CDS characteristics and message exchanges required for maintaining the CDS. We find that the algorithm maintains a stable leader set dominating all nodes in the network for a wide range of mobility levels but struggles to maintain connectivity at high mobility levels. We also quantify the portions of the control messages for CDS maintenance that are exchanged through physical carrier sensing. We find that the parallel algorithm manages to greatly reduce the reliance on intact message receptions.
物理载波传感迄今主要用于改进无线网络中的介质访问控制。最近,一种致力于广泛利用物理载波感知来构建和维护连接支配集(CDS)的并行算法被提出,该算法也被称为干扰范围大于传输范围的无线自组织网络中的钳形网络、骨干网络或覆盖网络。现有的算法评价仅限于理论渐近界和静态网络的模拟。本文通过离散事件仿真,对移动自组网中基于物理载波感知的CDS维护进行了评估。对于大范围的节点速度和节点密度,我们评估了CDS特性和维护CDS所需的消息交换。我们发现,该算法在大范围的移动水平下保持一个稳定的领导集,主导网络中的所有节点,但在高移动水平下难以保持连通性。我们还量化了通过物理载波感知交换的用于CDS维护的控制消息的部分。我们发现并行算法可以大大减少对完整消息接收的依赖。
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引用次数: 2
The Effect of Different Injection Strategies and Intake Conditions on the Emissions Characteristics in a Diesel Engine 不同喷射策略和进气条件对柴油机排放特性的影响
Pub Date : 2009-06-02 DOI: 10.1155/2009/105363
M. Gorji-Bandpy, S. Soleimani, D. Ganji
Choosing various injection strategies and intake conditions are potentially effective techniques to reduce exhaust emission from diesel engines. The purpose of this study is to investigate the effect of different spray incoming angles, different spray cone angles, different injection timing, and different intake temperatures together with emission characteristics on a heavy duty diesel engine via three dimensional computational fluid dynamics (CFD) procedures. Furthermore the effect of multiple injector combustion chamber and its benefits in pollutant reduction is studied. The principal results show the significant differences in soot and 𝑁𝑂 generation during combustion between above different strategies.
选择不同的喷射策略和进气条件是减少柴油机废气排放的潜在有效技术。采用三维计算流体动力学(CFD)方法,研究了不同喷角、不同喷锥角、不同喷时和不同进气温度对重型柴油机排放特性的影响。此外,还研究了多喷油器燃烧室在减少污染物方面的作用和效益。主要结果表明,不同的燃烧策略在燃烧过程中产生的烟灰和生成的二进制数据(𝑂)存在显著差异。
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引用次数: 6
Bifocal Stereoscopic Vision for Intelligent Vehicles 智能车辆双焦点立体视觉
Pub Date : 2009-03-29 DOI: 10.1155/2009/123231
F. Rovira-Más, Qi Wang, Qin Zhang
The numerous benefits of real-time 3D awareness for autonomous vehicles have motivated the incorporation of stereo cameras to the perception units of intelligent vehicles. The availability of the distance between camera and objects is essential for such applications as automatic guidance and safeguarding; however, a poor estimation of the position of the objects in front of the vehicle can result in dangerous actions. There is an emphasis, therefore, in the design of perception engines that can make available a rich and reliable interval of ranges in front of the camera. The objective of this research is to develop a stereo head that is capable of capturing 3D information from two cameras simultaneously, sensing different, but complementary, fields of view. In order to do so, the concept of bifocal perception was defined and physically materialized in an experimental bifocal stereo camera. The assembled system was validated through field tests, and results showed that each stereo pair of the head excelled at a singular range interval. The fusion of both intervals led to a more faithful representation of reality.
自动驾驶汽车的实时3D感知带来的诸多好处促使人们将立体摄像头整合到智能汽车的感知单元中。相机与物体之间的距离对于自动导航和保护等应用至关重要;然而,对车辆前方物体位置的错误估计可能会导致危险的行为。因此,在感知引擎的设计中有一个重点,那就是能够在相机前提供一个丰富而可靠的距离间隔。这项研究的目的是开发一种立体头,能够同时从两个摄像头捕捉3D信息,感知不同但互补的视野。为了做到这一点,双焦点感知的概念被定义和物理物化的实验双焦点立体相机。通过现场试验验证了该装配系统的有效性,结果表明,头部的每一对立体视觉都在一个奇异的距离区间内表现优异。这两个间隔的融合导致了对现实的更忠实的表现。
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引用次数: 9
Performance Analysis of CDMA WLL Systems with Imperfect Power Control and Imperfect Sectorization 不完全功率控制和不完全分割的CDMA WLL系统性能分析
Pub Date : 2008-09-30 DOI: 10.1155/2008/413821
S. El-Dolil
Wireless local loop (WLL) provides reliable, flexible, and economical access to the local telephone service using radio technology in the place of traditional wireline. In this paper, an analytical model is derived to evaluate the effect of both imperfect power control and imperfect sectorization on the performance of code division multiple access (CDMA) WLL systems. The results show that the capacity degradation, due to imperfect power control, is about 25.8% and 11.5% for single cell and multiple cell systems, respectively. Increasing the overlapping angle from 0∘ to 5∘ causes the capacity gain to decrease from 6 to 5.53, while the corresponding sectorization efficiency drops from 100% to 92.3%.
无线本地环路(WLL)利用无线电技术代替传统的有线,提供可靠、灵活和经济的本地电话服务。本文建立了不完全功率控制和不完全分割对码分多址(CDMA) WLL系统性能影响的分析模型。结果表明,由于功率控制不完善,单电池和多电池系统的容量退化分别约为25.8%和11.5%。将重叠角从0°增加到5°,使容量增益从6°下降到5.53°,而相应的扇形效率从100%下降到92.3%。
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引用次数: 2
Routing in Vehicular Networks: Feasibility, Modeling, and Security 车联网中的路由:可行性、建模和安全性
Pub Date : 2008-04-21 DOI: 10.1155/2008/267513
Ioannis Broustis, M. Faloutsos
Vehicular networks are sets of surface transportation systems that have the ability to communicate with each other. There are several possible network architectures to organize their in-vehicle computing systems. Potential schemes may include vehicle-to-vehicle ad hoc networks, wired backbone with wireless last hops, or hybrid architectures using vehicle-to-vehicle communications to augment roadside communication infrastructures. Some special properties of these networks, such as high mobility, network partitioning, and constrained topology, differentiate them from other types of wireless networks. We provide an in-depth discussion on the important studies related to architectural design and routing for such networks. Moreover, we discuss the major security concerns appearing in vehicular networks.
车辆网络是一组具有相互通信能力的地面运输系统。有几种可能的网络架构来组织他们的车载计算系统。潜在的方案可能包括车对车自组织网络、带无线最后一跳的有线骨干网络,或者使用车对车通信来增强路边通信基础设施的混合架构。这些网络的一些特殊属性,如高移动性、网络分区和受限拓扑,使它们区别于其他类型的无线网络。我们对此类网络的架构设计和路由相关的重要研究进行了深入的讨论。此外,我们还讨论了车辆网络中出现的主要安全问题。
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引用次数: 50
期刊
International Journal of Vehicular Technology
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