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1.
项鹏  王荣 《量子电子学报》2007,24(6):736-742
在光网络中,光信号沿着路由与波长分配(RWA)算法选定的光通路传输的过程中会受到各种信号损伤的影响而导致信号质量的不断下降,严重影响着业务的服务质量(QoS).而光网络中多样化的客户层业务往往有着不同的QoS的需求,因此有必要根据不同的业务QoS需求对光信号损伤的影响进行不同程度的控制.针对这一问题,提出了一种能同时考虑信号损伤限制和服务质量区分的动态RWA算法,并通过计算机仿真的方法对其性能进行了分析和验证.结果表明:该算法既能克服光网络中信号损伤的影响又能为不同级别的业务提供不同的QoS保证,更贴近实际需求.  相似文献   
2.
一种保证EPON中DBA公平性的算法   总被引:1,自引:0,他引:1  
动态带宽分配是以太网无源光网络(EPON)系统的一个重要研究领域,文章提出一种在EPON系统中保证动态带宽分配公平性的新型算法.该算法计算量适中, 同时兼顾了动态带宽分配的效率和公平性.文中通过推导给出了最优算法,并在模拟流量下进行了仿真,通过与已有算法的对比,证明其有很好的性能.  相似文献   
3.
A new effective and reliable channel-timeslot allocation algorithm has been proposed, which is applied in WDM optical networks using fiber as their media to allocate the operational request. This new algorithm can differentiate the priority of all requests and avoid conflict and collision in the process of distributing channel and timeslot for the data waiting for transmission. The method in calculating the best wavelength channel and the best timeslot number is simply given. The algorithm is carried out in a math language. On the basis of the experiment results, the performance and feasibility of the algorithm are analyzed, which prove that the allocation method can reach the requirements of an algorithm both in space complexity and time complexity.  相似文献   
4.
基于以太网传输MPEG-2码流的协议研究   总被引:3,自引:2,他引:1  
从以太网作为MPEG-2码流传输的承载体出发,提出了一种新的基于以太网链路层传输MPEG-2码流的协议.阐明了新协议的构架和现有IP协议的关系,并在标准以太网帧结构基础上对此协议的封装进行描述和定义.对使用该种协议传输数字电视MPEG-2码流的服务质量进行分析,提出了一种较为切实可行的传输服务策略.仿真实验验证了采用该协议在一定网络负载下传输MPEG-2码流的可行性.  相似文献   
5.
This paper presents a framework that addresses Quality of Service (QoS) for industrial wireless sensor networks as a real-time measurable set of parameters within the context of feedback control, thereby facilitating QoS management. This framework is based on examining the interaction between the industrial control processes and the wireless network. Control theory is used to evaluate the impact of the control/communication interaction, providing a methodology for defining, measuring, and quantifying QoS requirements. An example is presented illustrating the wireless industrial sensor network (WISN) QoS management framework for providing dynamic QoS control within WISN. The example focuses on WISN operating in a time-varying RF interference environment in order to manage application-driven QoS latency constraints.  相似文献   
6.
Recent research based on traffic measurements shows that Internet traffic flows have a fractal nature (i.e., self-similarity property), which causes an underestimation of network engineering parameters when using the conventional Poisson model. Preliminary field measurements demonstrate that packet data traffic in wireless communications also exhibits self-similarity. In this paper, we investigate the queuing behavior of self-similar traffic flows for data applications in a packet-switching single-server wireless network. The traffic is generated by an on–off source with heavy-tailed on periods and exponentially distributed off periods. We extend previous analysis of a relation among the asymptotic distribution of loss probability, traffic specifications, and transmission rate for a wireline system to a wireless system, taking into account wireless propagation channel characteristics. We also investigate the multiplexing of heavy-tailed traffic flows with a finite buffer for the downlink transmission of a wireless network. Computer simulation results demonstrate that assumptions made in the theoretical analysis are reasonable and the derived relationships are accurate.  相似文献   
7.
The GEMSS project has developed a service-oriented Grid that supports the provision of medical simulation services by service providers to clients such as hospitals. We outline the GEMSS architecture, legal framework and the security features that characterise the GEMSS infrastructure. High levels of quality of service are required and we describe a reservation-based approach to quality of service, employing a quality of service management system that iteratively finds suitable reservations and uses application specific performance models. The GEMSS Grid is a commercial environment so we support flexible pricing models and a FIPA reverse English auction protocol. Signed Web Service Level Agreement contracts are exchanged to commit parties to a quality of service agreement before job execution occurs. We run four experiments across European countries using high performance computing resources running advanced resource reservation schedulers. These experiments provide evidence for our Grid’s rational behaviour, both at the level of service provider quality of service management and at the higher level of the client choosing between competing service providers. The results lend support to our economic model and the technology we use for our medical application domain.  相似文献   
8.
Deployment of IP multimedia services with guaranteed Quality of Service (QoS) is a primary requirement for Beyond 3G (B3G) systems. In this paper we propose a new architecture to support Internet QoS-sensitive services (e.g., video-conferencing, voice over IP, interactive gaming), thus providing users with end-to-end QoS guarantees. In particular, the paper discloses a new hybrid Intserv/Diffserv scheme for handling IP packets and an interworking procedure with the RSVP protocol which allows to support QoS over an integrated, multi-segment network. Such scheme is implemented by means of a suitable Quality of service Support Module (QASM). Advantages and drawbacks of QASM are discussed and the impact on both system architecture and Multi-Mode Mobile Terminal is investigated. Performance evaluations, carried out via computer simulations, confirm the effectiveness of the proposed solution.  相似文献   
9.
Only recently have methodical tools adequate to design real-time systems been formally introduced in design methodologies. Naturally, they were present from the beginning, but due to the large diversity of embedded systems’ areas of deployment, specially dedicated formalisms have been developed and used. High-level language programming and integration of modeling formalisms into design methods eased the development of more complex real-time applications. With the emerging object-oriented programming languages and design methods, their integration into larger information systems has become more transparent. It was the UML methodology, however, which eventually merged also the design methods and concepts of real-time systems into a consistent whole. It took a large consortium and a long process to persuade industry of the benefits the new integral methodology can offer. On the other hand, there are some trade-offs, and there are some features not completely covered, yet. Here, a different, more straightforward approach to program and design (embedded) real-time systems is presented. Since it emerged from the real-time community, it includes most features relevant there. Independent of the UML profile for schedulability, performance and time specification, a profile was devised for use in PEARL-oriented UML design. The strengths of the mentioned language and design methods for QoS-oriented design of (embedded) real-time systems are emphasised throughout this article.  相似文献   
10.
作为下一代网络的重要组成部分,Ad Hoc网是目前的一个重要研究热点。根据Ad Hoc网络的特点,总结了Ad Hoc网中的路由技术。从路由查找和维护的角度分析和归纳了网络中关于单播路由、组播路由和QoS路由等的技术特点,指出了不同协议及算法的设计思路和解决策略,为寻求和设计更为高效的适合自组网特点的新型路由技术奠定基础。  相似文献   
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