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目前互连线的工艺变化问题已成为影响超大规模集成电路性能的重要因素.考虑了互连线工艺变化的空间相关性,将工艺参数变化建模为具有自相关性的随机过程,采用数值仿真及拟合方法得到寄生参数的近似表达式,最后基于Elmore延迟度量分析了随机工艺变化对互连延迟的影响,提出了工艺变化下互连延迟统计特性的估算方法,并通过仿真实验对方法的有效性进行了验证. 相似文献
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介绍了一种适用于Interleaved Polling with stop方式带宽分配算法的EPON系统仿真模型.该模型可以对最大端到端延迟、平均端到端延迟和业务吞吐量等参数进行仿真.在此模型的基础上仿真了一种基于QoS的区分优先级的带宽分配算法,最后给出了相应的仿真结果. 相似文献
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提出了一种非精确状态下满足多QoS约束的动态组播路由算法——DMIQ,该算法采用改进的BF算法作为路径搜索算法,WFQ作为分组调度机制,链路延迟不确定且服从均匀分布,能在非精确状态且满足带宽、延迟抖动和丢包率约束的前提下确定具有最小跳数和开销的动态组播路由.仿真实验表明,DMIQ能在非精确状态且满足多QoS约束的前提下建立动态组播路由,在路由请求平均成功率、平均延迟和平均跳数等衡量指标下表现出良好的性能. 相似文献
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一种基于Evalvid的H.264视频QoS评估改进系统 总被引:1,自引:0,他引:1
提出了一种基于Evalvid的H.264视频传输服务质量(QoS)评估改进系统,该系统在Ns-2网络仿真器上运行,实现了对丢包率、延时以及延迟抖动等QoS参数的测量,并利用Evalvid工具实现了对接收端视频PSNR值的计算.系统采用了基于帧类型的区分优先级的传输策略,实验结果表明,它能使传输后的视频PSNR值得到明显提高. 相似文献
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推导了基于高斯脉冲的一维超宽带阵列的时域辐射信号表达式,分析了阵列最大辐射方向与网络延迟、阵元间距的函数关系,提出了辐射信号合成波形宽度与辐射方向的近似函数关系式,仿真分析了阵列辐射波形与阵元数、阵元间距、辐射脉冲宽度、斜距、网络延迟等参数的依赖关系.同时指出信号宽度参数是估计雷达与目标相对角位置的可用信息,对近程超宽带冲激引信的研究有重要参考价值. 相似文献
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Dae-Hee Kim Danlu Zhang Naga Bhushan Rajesh Pankaj Seong-Jun Oh 《Wireless Networks》2013,19(2):131-144
This paper proposes an admission control algorithm for cellular networks based on the direct and dynamic monitoring of quality of services (QoS) performance metrics—both system delay tail and residual throughput. The main purpose of directly monitoring these QoS performance metrics is to more precisely meet the QoS requirements. The delay tail is efficiently estimated by the proposed algorithm and the total residual throughput is determined based on the total achieved throughput and total required throughput. With the estimated delay tails and measured residual throughput, the admission or rejection of a new user is determined at each base station. By doing so, the admission control algorithm improves resource utilization by guaranteeing the QoS. Additionally, the cellular system becomes more robust against the time-varying fading channel environment. The simulation results of the long term evolution downlink system show that the proposed algorithm can achieve a significant improvement in results compared to those of reference schemes. A general Neyman–Pearson-like framework is also used in evaluating the various admission control mechanisms. 相似文献
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Advertising interdomain QoS routing information 总被引:1,自引:0,他引:1
Li Xiao Jun Wang King-Shan Lui Nahrstedt K. 《Selected Areas in Communications, IEEE Journal on》2004,22(10):1949-1964
To enable end-to-end quality-of-service (QoS) guarantees in the Internet, based on the border gateway protocol (BGP), interdomain QoS information advertising, and routing are important. However, little research has been done in this area so far. Two major challenges, scalability and heterogeneity, make the QoS extension to BGP difficult. In the existing routing schemes, static and instantaneous QoS metrics, such as link capacity and available bandwidth, are used to represent QoS routing information, but neither of them can solve the two challenges well. In this paper, BGP is extended to advertise available bandwidth and delay information of routes, but, instead of using the traditional deterministic metrics, a series of statistical metrics, available bandwidth index (ABI), delay index (DI), available bandwidth histogram (ABH), and delay histogram (DH), are defined and applied to QoS information advertising and routing. Two major contributions of the proposed statistical metrics are: 1) QoS information is abstracted into one or several probability intervals and, thus, the heterogeneous and dynamic QoS information can be represented more flexibly and precisely and 2) by capturing the statistical property of the detailed distribution of QoS information, these new metrics are efficient and they can highly decrease the message overhead in routing, thereby making the QoS advertising and routing scalable. Our extensive simulations confirm both contributions of the QoS extension to BGP very well. Moreover, besides BGP, these statistical metrics can be applied to other networks and protocols to represent QoS information in a more scalable and precise way. 相似文献
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To facilitate the efficient support of quality of service (QoS) in next-generation wireless networks, it is essential to model a wireless channel in terms of connection-level QoS metrics such as data rate, delay, and delay-violation probability. However, the existing wireless channel models, i.e., physical-layer channel models, do not explicitly characterize a wireless channel in terms of these QoS metrics. In this paper, we propose and develop a link-layer channel model termed effective capacity (EC). In this approach, we first model a wireless link by two EC functions, namely, the probability of nonempty buffer, and the QoS exponent of a connection. Then, we propose a simple and efficient algorithm to estimate these EC functions. The physical-layer analogs of these two link-layer EC functions are the marginal distribution (e.g., Rayleigh-Ricean distribution) and the Doppler spectrum, respectively. The key advantages of the EC link-layer modeling and estimation are: 1) ease of translation into QoS guarantees, such as delay bounds; 2) simplicity of implementation; and 3) accuracy, and hence, efficiency in admission control and resource reservation. We illustrate the advantage of our approach with a set of simulation experiments, which show that the actual QoS metric is closely approximated by the QoS metric predicted by the EC link-layer model, under a wide range of conditions. 相似文献
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Popularity of IEEE 802.11 networks has increased dramatically over the past number of years. Nowadays audio/video conferencing, gaming and other quality of service (QoS) sensitive services are being delivered to the end users over wireless. Commonly probability for a packet to overstay a specific timeout serves as a QoS metric, and obtaining media access control layer packet delay distribution is highly important for this QoS prediction. Usually wireless devices are equipped with energy supplies of limited capacity, and accurate estimation of their energy expenditure is essential from the network design point of view. Meanwhile, as packets of longer delay normally have higher energy transmission cost, there is a certain dependency between the two metrics. This paper considers internal structure of the metrics and proposes a mathematical model that allows obtaining their individual distributions together with the joint distribution. The model presents a random sum, where the summand formation is determined by a Terminating Markov Process. The model has been validated through comparison with results of NS3 simulation. 相似文献
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Yu-Jung Chang Feng-Tsun Chien Kuo C.-C.J. 《Selected Areas in Communications, IEEE Journal on》2007,25(4):657-666
Performance analysis of multiuser orthogonal frequency division multiplexing (OFDM-TDMA) and orthogonal frequency division multiple access (OFDMA) networks in support of multimedia transmission is conducted in this work. We take a cross-layer approach and analyze several quality-of-service (QoS) measures that incilude the bit rate and the bit error rate (BER) in the physical layer, and packet average throughput/delay and packet maximum delay in the link layer. The authors adopt a cross-layer QoS framework similar to that in IEEE 802.16, where service classification, flow control and opportunistic scheduling with different subcarrier/bit allocation schemes are implemented. In the analysis, the Rayleigh fading channel in the link layer is modeled by a finite-state Markov chain, and the channel state information (CSI) is assumed to be available at the base station. With the M/G/1 queueing model and flow control results, the analysis provides important insights into the performance difference of these two multiaccess systems. The derived analytical results are verified by extensive computer simulation. It is demonstrated by analysis and simulation that OFDMA outperforms OFDM-TDMA in QoS metrics of interest. Thus, OFDMA has higher potential than OFDM-TDMA in supporting multimedia services. 相似文献
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Virtual partitioning resource allocation for multiclass traffic in cellular systems with QoS constraints 总被引:3,自引:0,他引:3
Jianxin Yao Mark J.W. Tung Chong Wong Yong Huat Chew Kin Mun Lye Kee-Chaing Chua 《Vehicular Technology, IEEE Transactions on》2004,53(3):847-864
Resource allocation is a vital component of call-admission control that determines the amount of resource to assign to new and handoff connections for quality-of-service (QoS) satisfaction. In this paper, we present approximate analytical formulations of virtual partitioning resource-allocation schemes for handling multiclass services with guard channels in a cellular system. Resource-allocation models for best effort and guarantee access with preemption for best effort traffic and virtual partition with preemption for all classes are investigated. The analytical models, derived using a K-dimensional Markov chain, are solved using preemption rules for these schemes. Call-level grade of service, such as new-call-blocking probability, handoff-call-blocking probability, and system utilization, and packet-level QoS, such as packet-loss probability, are used as performance metrics. The performances of fast and slow mobile users are evaluated analytically and by simulation. The analytical and simulation results show excellent agreement. A method to maximize system utilization through joint optimization of call-/packet-level parameters is proposed. Numerical results indicate that significant gain in system utilization is achieved. 相似文献
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为了实现同一地域范围内的众多用户在有限带宽条件下提出的高QoS要求,本文对基于IEEE 802.16标准的宽带无线接入网中数据包级QoS(Quality of Service)性能进行了研究.具体做法是,首先采用批马尔可夫到达过程(BMAP,Batch Markov Arrival Process)和连续时间马尔科夫链(CTMC,Continuous Time Markov Chain)对到达过程和流量源进行建模,得到更符合实际和更准确的排队模型;然后基于状态空间,对一个无线接入网络系统进行建模,通过对得到的系统模型并结合前面得到的排队模型的深入分析,从而获得该模型下的各项QoS性能指标,如平均队列长度、丢包率、队列吞吐量和平均包时延.仿真实验结果表明,本文提出的算法模型相比于其他典型的算法模型,能够使得各项QoS性能指标有较大的改善和提高. 相似文献
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QoS-based routing of multimedia streams in computer networks 总被引:6,自引:0,他引:6
Vogel R. Herrtwich R.G. Kalfa W. Wittig H. Wolf L.C. 《Selected Areas in Communications, IEEE Journal on》1996,14(7):1235-1244
Continuous media such as audio and video require a certain quality-of-service (QoS) when transferred through computer networks. The selection of a network route for a particular media stream should hence take into account which route is best-suited for providing this QoS. QoSFinder is a method for QoS-based routing of multimedia streams. It is based on a path vector protocol that takes into account throughput, delay, and loss rate of individual route segments. A simulation of QoSFinder shows that its heuristic is superior to metrics that are only based on one of these parameters. QoSFinder increases the probability of finding suitable paths through networks for distributed multimedia applications 相似文献
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This paper investigates the quality-of-service (QoS)-driven multicast routing problem in a sparse-splitting optical network. The main objective is to minimize the total cost of wavelength channels utilized by the light-tree while satisfying required QoS parameters. In this paper, both the optical-layer constraints (e.g., optical signal power) and application-layer requirements (e.g., end-to-end delay and inter-destination delay variation) are considered as the QoS parameters. First, integer linear programming (ILP) formulations to solve the optimal multicast routing problem with the given QoS parameters are presented. Solving the ILP formulations for large-scale networks can easily overwhelm the capabilities of state-of-the-art computing facilities, and hence, a heuristic algorithm is proposed to construct a feasible light-tree that satisfies the required QoS parameters in large-scale networks. Simulation results demonstrate the performance of the proposed heuristic algorithm in terms of the cost of utilized wavelength channels. 相似文献
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Javier Gomez Luis A. Mendez Victor Rangel Andrew T. Campbell 《Telecommunication Systems》2011,47(3-4):303-321
Mobile ad hoc networks typically use a common transmission power approach for the discovery of routes and the transmission of data packets. In this paper we present PCQoS; a power-controlled Quality of Service (QoS) scheme for wireless ad hoc networks which builds QoS mechanisms for specific applications that wish to tradeoff better QoS performance for sub-optimal paths. PCQoS allows selected flows to modify their transmit power as a way to add and remove relay nodes from their paths in order to coarsely modify their observed application QoS performance. We present simulation results and show that PCQoS can be used to provide coarse control over traditional QoS metrics (e.g., delay, throughput). To the best of our knowledge the PCQoS protocol represents the first attempt to use variable-range transmission control as a means to provide QoS differentiation to applications in wireless ad hoc networks. 相似文献