共查询到20条相似文献，搜索用时 15 毫秒
1.
Liren Zhang Huirong Fu Chee Hock Ng 《International Journal of Communication Systems》2001,14(10):941-960
This paper focuses on the optimization of network bandwidth allocation and buffer dimensioning to transport pre‐stored MPEG video data from source to playback destination across ATM networks. This is one of the most important issues in the support of video‐on‐demand (VoD) service. This paper provides a novel scheme in the dynamic allocation of bandwidth to segments of video using ABR mode. The dynamic bandwidth allocation is based on a new concept, called playback tunnel which is obtained from the traffic characteristics of the pre‐stored MPEG video trace to determine the optimum of transmission bandwidth as well as the buffer capacity to ensure that the playback buffer neither underflows nor overflows. The proposed scheme is tested with real‐life MPEG video traces. The obtained results have shown its significant performance improvement in terms of the capacity of playback buffer, the start‐up playback delay, the size of video segment and the network multiplexing gain. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
2.
Mario Marchese Maurizio Mongelli 《International Journal of Communication Systems》2007,20(9):1059-1079
The paper proposes a bandwidth allocation scheme to be applied at the interface between upper layers (IP, in this paper) and Medium Access Control (MAC) layer over IEEE 802.16 protocol stack. The aim is to optimally tune the resource allocation to match objective QoS (Quality of Service) requirements. Traffic flows characterized by different performance requirements at the IP layer are conveyed to the IEEE 802.16 MAC layer. This process leads to the need for providing the necessary bandwidth at the MAC layer so that the traffic flow can receive the requested QoS. The proposed control algorithm is based on real measures processed by a neural network and it is studied within the framework of optimal bandwidth allocation and Call Admission Control in the presence of statistically heterogeneous flows. Specific implementation details are provided to match the application of the control algorithm by using the existing features of 802.16 request–grant protocol acting at MAC layer. The performance evaluation reported in the paper shows the quick reaction of the bandwidth allocation scheme to traffic variations and the advantage provided in the number of accepted calls. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
3.
Quang‐Dung Ho Mohamed Ashour Tho Le‐Ngoc 《Wireless Communications and Mobile Computing》2011,11(9):1254-1265
This paper studies and develops efficient traffic management techniques for downlink transmission at the base station (BS) of multi‐service IP‐based networks by combining quality‐of‐service (QoS) provision and opportunistic wireless resource allocation. A delay‐margin‐based scheduling (DMS) for downlink traffic flows based on the delays that each packet has experienced up to the BS is proposed. The instantaneous delay margin, represented by the difference between the required and instantaneous delays, quantifies how urgent the packet is, and thus it can determine the queuing priority that should be given to the packet. The proposed DMS is further integrated with the opportunistic scheduling (OPS) to develop various queueing architectures to increase the wireless channel bandwidth efficiency. Different proposed integration approaches are investigated and compared in terms of delay outage probability and wireless channel bandwidth efficiency by simulation. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
4.
This paper presents a study of a cross‐layer design through joint optimization of spectrum allocation and power control for cognitive radio networks (CRNs). The spectrum of interest is divided into independent channels licensed to a set of primary users (PUs). The secondary users are activated only if the transmissions do not cause excessive interference to PUs. In particular, this paper studies the downlink channel assignment and power control in a CRN with the coexistence of PUs and secondary users. The objective was to maximize the total throughput of a CRN. A mathematical model is presented and subsequently formulated as a binary integer programming problem, which belongs to the class of non‐deterministic polynomial‐time hard problems. Subsequently, we develop a distributed algorithm to obtain sub‐optimal results with lower computational complexity. The distributed algorithm iteratively improves the network throughput, which consists of several modules including maximum power calculation, excluded channel sets recording, base station throughput estimation, base station sorting, and channel usage implementation. Through investigating the impacts of the different parameters, simulation results demonstrates that the distributed algorithm can achieve a better performance than two other schemes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
In order to support the quality‐of‐service (QoS) requirements for real‐time traffic over broadband wireless networks, advanced techniques such as space‐time diversity (STD) and multicarrier direct‐sequence code division multiple access (MC‐DS‐CDMA) are implemented at the physical layer. However, the employment of such techniques evidently affects the QoS provisioning algorithms at the medium access control (MAC) layer. In this paper, we propose a space‐time infrastructure and develop a set of cross‐layer real‐time QoS‐provisioning algorithms for admission control, scheduling, and subchannel‐allocations. We analytically map the parameters characterizing the STD onto the admission‐control region guaranteeing the real‐time QoS. Our analytical analyses show that the proposed algorithms can effectively support real‐time QoS provisioning. Also presented are numerical solutions and simulation results showing that the STD can significantly improve the QoS provisioning for real‐time services over wireless networks. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
6.
Kuan‐Lin Chiu Yuh‐Shyan Chen Ren‐Hung Hwang 《International Journal of Communication Systems》2011,24(6):789-809
The next generation wireless communication system will likely be heterogeneous networks, as various technologies can be integrated on heterogeneous networks. A mobile multiple‐mode device can easily access the Internet through different wireless interfaces. The mobile multiple‐mode device thus could switch to different access points to maintain the robustness of the connection when it can acquire more resources from other heterogeneous wireless networks. The mobile multiple‐mode device therefore needs to face the handover problem in such environment. This work introduces Session Initiation Protocol (SIP)‐based cross‐layer scheme to support seamless handover scheme over heterogeneous networks. The proposed scheme consists of a battery lifetime‐based handover policy and cross‐layer fast handover scheme, called the SIP‐based mobile stream control transmission protocol (SmSCTP). This work describes the major idea of the proposed scheme and infrastructure. The proposed scheme has been implemented in Linux system. The simulation and numerical results demonstrate that the proposed SmSCTP scheme yields better signaling cost, hand‐off delay time, packet loss and delay jitter than SIP and mSCTP protocols. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
7.
Tomoko Kudo Toshihiro Taketa Yukio Hiranaka 《Electronics and Communications in Japan》2019,102(9):27-37
In this paper, we propose, verify, and evaluate a method combining cross‐layer method and bandwidth allocation to overcome the difficulty of flow control in a network with large bandwidth delay product. When the bandwidth delay product is large, there are problems with the convergence time, efficiency and stability of bandwidth utilization, and fairness among traffics of different round‐trip time. As a result of examining the conventional methods, we propose a novel method that can be realized as a functional addition to the existing transmission control protocol (TCP) flow control with improvement in utilization efficiency, fairness, stability, and convergence time. The method is compared with TCP Reno, FAST TCP, CUBIC, Explicit Congestion Notification, and eXplicit Control Protocol by simulation, and is confirmed as having good characteristics. 相似文献
8.
Xiang Yang Weiping Wang Mingming Lu Jianxin Wang Xi Zhang 《Wireless Communications and Mobile Computing》2016,16(14):1922-1942
Because of the broadcast and overhearing capability of wireless networks, network coding can greatly improve throughput in wireless networks. However, our investigation of existing inter‐session network coding protocols found that the short‐term unfairness that existed in 802.11‐based medium access control (MAC) protocols actually decreases the coding opportunity, which in turn compromises the throughput gain of network coding. To alleviate the negative impact of this unfairness, we propose a coding‐aware cross‐layer heuristic approach to optimize the coordination of network coding and MAC layer protocol, named FairCoding, which can significantly increase coding opportunities for inter‐session network coding through a fair short‐term traffic allocation for different coding flows. Experiment evaluation shows that the proposed mechanism can bring more coding opportunities and improve the total throughput of wireless mesh networks by up to 20%, compared with the coding mechanism, without considering the negative impact of the short‐term unfairness. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
9.
Admission controls are required to determine whether new connections should be admitted to networks. These controls ensure the quality of service (QoS) for data transmission. This paper introduces three measurement‐based admission control algorithms called Measured Sum, Hoeffding Bound, and Adaptive Weight Factor. The unfairness of these algorithms in a heterogeneous environment is investigated. Simulation results indicate that the fairness of the Measured Sum exceeds that of the other methods. Admission of connections with large peak rates or travelling many hops can be difficult. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
10.
为了保证认知无线电传感器网络(CRSN)的服务质量(QoS),需精确求解所采用协议的性能边界,为此提出了一种基于随机网络演算(SNC)的QoS性能边界分析方法.以CRSN中的和式增加积式减少(AIMD)拥塞控制机制为评估对象,以通信时延和数据积压为QoS性能指标.根据CR资源传感器的发送速率分布,利用基于矩量母函数(MGF)的随机网络演算推导出AIMD机制的时延和积压边界模型.实验结果表明,不同CRSN场景中的模型计算值都在理论边界范围之内,证明了该边界分析模型具有良好的性能. 相似文献
11.
自适应的认知无线Mesh网络QoS约束的路由与频谱分配算法 总被引：1，自引：0，他引：1
提出了一种自适应的满足QoS约束的路由与频谱分配(SA2JR)算法,SA2JR的目标是:在满足无线业务QoS约束的情况下,最大化无线业务接受率,让尽可能多的无线业务需求能够被满足.SA2JR包括2个部分,按需的κ-路径路由(κ-Routing)算法,以及QoS驱动的频谱分配(QDSA)算法.κ-Routing负责为每一个需求产生κ条潜在路由路径,QDSA算法自适应地进行频谱分配,目标是从κ-Routing产生的κ条潜在路由路径中找出一条满足QoS约束的可行路由路径.仿真结果表明SA2JR能达到预定目标,获得了较高的无线业务接受率. 相似文献
12.
Chia‐Cheng Hu 《Wireless Communications and Mobile Computing》2012,12(2):206-218
Previous quality‐of‐service (QoS) routing protocols in mobile ad hoc networks (MANETs) determined bandwidth‐satisfied routes for QoS applications. Since the multi‐rate enhancements have been implemented in MANETs, QoS routing protocols should be adapted to exploit them fully. However, existing works suffer from one bandwidth‐violation problem, named the hidden route problem (HRP), which may arise when a new flow is permitted and only the bandwidth consumption of the hosts in the neighborhood of the route is computed. Without considering the bandwidth consumption to ongoing flows is the reason the problem is introduced. This work proposes a routing protocol that can avoid HRP for data rate selection and bandwidth‐satisfied route determination with an efficient cross‐layer design based on the integration of PHY and MAC layers into the network layer. To use bandwidth efficiently, we aim to select the combination of data rates and a route with minimal bandwidth consumption to the network, instead of the strategy adopted in the most previous works by selecting the combination with the shortest total transmission time. Using bandwidth efficiently can increase the number of flows supported by a network. Copyright 2010 John Wiley & Sons, Ltd. 相似文献
13.
Information‐Centric Networking (ICN) has been accepted to overcome some weaknesses of the current Internet architecture, showing that “what is being exchanged” is more important than “who are exchanging information.” Given the inadequate considerations on Quality of Service (QoS) and energy saving in ICN routing, we propose in this paper a routing algorithm to enhance the two aspects. At first, on one hand, Cauchy distribution is used as a fuzzy model to evaluate users' QoS requirements, such as bandwidth, delay, and error rate; on the other hand, we formulate energy saving problem to evaluate the green quality of routing algorithm. Then, we design a link selection approach by considering QoS and energy saving, which belongs to a multi‐objective decision problem resolved by intelligent drops algorithm. Finally, we implement the proposed algorithm and compare it with the famous adaptive forwarding mechanism in terms of some significant metrics, and the experimental results reveal that the proposed algorithm is more efficient. 相似文献
14.
15.
通过研究感知无线电技术的发展现状,分析其技术研究的内容与方向,阐述了感知无线电技术对无线标准及产业发展的短期和长期影响。 相似文献
16.
研究了网络编码应用到认知无线电中的可能,发现在认知无线电中应用网络编码技术,可以减少非授权用户和授权用户的冲突概率,增加无线网络的实际吞吐率.最后通过仿真验证了网络编码优化认知无线电网络性能的有效性. 相似文献
17.
Paul J. M. Havinga Gerard J. M. Smit 《Wireless Communications and Mobile Computing》2001,1(2):165-184
In this paper we identify the most prominent problems of wireless multimedia networking and present several state‐of‐the‐art solutions with a focus on energy efficiency. Three key problems in networked wireless multimedia systems are: (1) the need to maintain a minimum quality of service over time‐varying channels; (2) to operate with limited energy resources; and (3) to operate in a heterogeneous environment. We identify two main principles to solve these problems. The first principle is that energy efficiency should involve all layers of the system. Second, Quality of Service is an essential mechanism for mobile multimedia systems not only to give users an adequate level of service, but also as a tool to achieve an energy‐efficient system. Owing to the dynamic wireless environment, adaptability of the system will be a key issue in achieving this. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
18.
A load-transfer-based joint admission control (LJAC) algorithm in heterogeneous networks was proposed.The access requirements of users were admitted based on load balancing,the dynamic load transfer of traffics in the overlapping coverage areas of heterogeneous networks were introduced,and the influence of such factors as the layout of heterogeneous networks and the vertical handoff was considered in the algorithm.The integrated system of heterogeneous networks was modeled as a multidimensional Markov chain,the steady-state probabilities were obtained and the quality of service (QoS) performance metrics were derived.Based on the Poisson point process theory,the upper bound of capacity of the heterogeneous networks satisfying QoS limitations was obtained.The admission control parameters of the integrated system of heterogeneous networks were optimized in order to maximize the resource utilization rate as well as guaranteeing the QoS of users.The simulation results demonstrate lower traffic blocking probability,lower failure probability of vertical handoff requirements,and larger system capacity gain can be achieved by using the proposed LJAC algorithm. 相似文献
19.
Liang Xue Bo Yang Jijun Zhao Zhixin Liu Xinping Guan 《Wireless Communications and Mobile Computing》2015,15(5):848-867
Cognitive radio (CR) networks comprise a number of spectrum agile nodes with the capability of spectrum detection. Applying techniques of spectrum sharing in CR networks can achieve the efficient utilization of network resources. Usually, data rates of user sessions are time varied because of the dynamic behaviors of CR networks. It is expected that the occurrence of link outage should be avoided and incorporated into the routing design under conditions of increasingly crowded spectrum. This paper proposes an integral framework, which considers these two correlated schemes (resource reconfiguration and robust routing) simultaneously. For that, the resource reconfiguration scheme is developed for the efficient usage of network resources and aims at reducing the occupancy of licensed bands. The link outage, resulting from random session rate, is confined within an acceptable range by using strategy of virtual ‘network portfolio’. A robust optimization approach is proposed to guarantee reliable data transmission among possible interfering links. Both these two items (resource reconfiguration and robust routing) are formulated in a framework of cross‐layer optimization. The evolutionary process of CR network states is provided in simulations, where the results show that the joint design proposal can achieve the least interferences among different licensed users while realizing robust routing. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
20.
Aiming at the problem that it is difficult to allocate spectrum resources to secondary users efficiently in cognitive heterogeneous wireless networks with heterogeneous spectrum attributes,dynamic channel conditions and diverse service requirements,a spectrum resource allocation strategy with maximum transmission rate was proposed.Firstly,the strategy aimed at maximizing the total transmission rate,and constrained the limited spectrum resources and user service requirements to construct a non-linear multi-constrained spectrum resource allocation 0-1 planning model.Then a polynomial time complexity simplification method was designed.According to idle spectrum information,channel conditions,business requirements and allocation decision history information,and the benefit matrix was constructed and modified to achieve constraint simplification,and the execution efficiency was improved by improving the coefficient matrix transformation strategy of the traditional Hungarian algorithm.Finally,the performance of the method was compared and analyzed by experiments.Experimental results show that the proposed method has higher transmission rate and execution efficiency. 相似文献