RPR业务的带宽管理

弹性分组环(RPR)是基于高度的伸缩弹性的高效的包交换光纤环网技术。RPR的业务带宽管理有很多方式和算法,文章从RPR网络管理软件的角度,阐述了RPR单节点预留带宽和全环业务带宽预留的机制,配合网络管理软件在分配全环各类业务时进行各类带宽限制,达到高优先级业务得到有效无拥塞的传输,低优先级的业务根据协议标准进行公平算法,来分配各自的带宽。文章从网络管理实现的角度,介绍对带宽进行管理的系统功能。     

以太网业务的带宽轮廓

以太网业务中一个比较重要的属性就是带宽轮廓属性.根据带宽轮廓用户可以按需购买带宽,而供应商则可以根据带宽的使用情况来收费并且为在带宽轮廓内的业务帧提供性能保证,供应商还可以根据带宽轮廓来更加有效地规划网络资源.通过带宽轮廓,业务供应商在每个UNI上可以提供多种业务同时每种业务都具有它们自己的带宽轮廓.对带宽轮廓参数、带宽轮廓算法以及带宽轮廓的业务属性进行了论述.     

多媒体业务在越区切换中服务质量保证方法的研究

为了降低多媒体业务在移动环境中的呼叫中断率,提高无线信道的利用率,该文提出了一种动态预留带宽分配机制(DRBA),该机制对到达的越区切换呼叫按业务类型区别处理,对于高优先级的实时业务,通过在邻近小区内预留带宽的方法降低呼叫中断率;对于非实时业务,当小区内的信道带宽不足以支持新到达的越区切换呼叫时,通过动态地借用实时业务过度预留的带宽,改善非实时业务的呼叫中断率,进一步达到提高无线信道利用率,为不同的业务类型提供公平的服务质量(QoS)的目标。     

D-PRMA：一种新的无线Ad Hoc网络资源预留MAC机制

支持资源预留的介质访问控制(MAC)机制是无线ad hoc网络提供服务质量保证的关键。本文在分析分组预留多址接入(PRMA)的基础上，给出了一种新的支持资源预留的无线ad hoc网络MAC机制：分布式PRMA(D-PRMA)。D—PRMA的主要特点是分布式的，这适合无线ad hoc网络无中心的特点，同时，D—PRMA具有很短的碰撞持续时间，支持不同速率的实时业务，避免了对分组的分片和重组。通过仿真，本文进一步分析了D—PRMA的性能，仿真结果表明D—PRMA能保证实时业务的带宽和时延。     

基于多门限预留机制的自适应带宽分配算法

针对异构无线网络融合环境提出了一种基于多门限预留机制的自适应带宽分配算法,从而为多业务提供QoS保证。该算法采用多宿主传输机制,通过预设各个网络中不同业务的带宽分配门限,并基于各个网络中不同业务和用户的带宽分配矩阵,根据业务k支持的传输速率等级需求和网络状态的变化,将自适应带宽分配问题转化为一个动态优化问题并采用迭代方法来求解,在得到各个网络中不同业务和用户优化的带宽分配矩阵的同时,在带宽预留门限和网络容量的约束条件下实现网络实时吞吐量的最大化,以提高整个异构网络带宽的利用效率。数值仿真结果显示,所提算法能够支持满足QoS需求的传输速率等级,减小了新用户接入异构网络的阻塞概率,提高了平均用户接入率并将网络吞吐量最大提高40%。     

联通分组网LTE承载规划浅议

介绍了中国联通分组网应对LTE业务,如何规划带宽、网络结构、分组网组网方案,以及分组网承载LTE的网内保护和网间保护的分组保护机制。     

AAL2分组话音复接器带宽分配算法的研究

本文根据分组话音业务的特点,结合分组话音业务服务质量的要求,特别是分组丢弃概率和平均分组排队时延的要求,研究AAL2分组话音复接器带宽分配算法.得出结论:对于无比特丢弃的AAL2分组话音复接器,按平均速率分配带宽基本上可以满足分组话音业务服务质量的要求;如果适当降低ATM VC的带宽利用率ρ(例如:令ρ=0.9),则可以进一步提高话音质量,获得令人满意的话音;对于带比特丢弃的AAL2分组话音复接器,按平均速率分配带宽,可以很好地满足分组话音业务服务质量要求,获得较高质量的话音.计算机仿真证实了上述结论是正确的.     

智能网络为三网融合奠基

在网络建设或网络改造的初期,运营商就要对网络做充分细致的规划,选用先进的智能化网关设备,配置成套完整的相关设备和网络管理、运营支撑系统。＂三网融合＂已渐渐成为当下的热点话题,但大家谈论最多的词语还是＂带宽＂,似乎是有了带宽就有了＂三网融合＂。然而由于把全部带宽都用作＂包月＂销售,运营商就可能没有足够的预留带宽来发展自身的IPTV高清视频业务,     

通过精细化流量管控助力全业务带宽经营

在全业务带宽经营的环境中．如何能在提高带宽利用率的同时还能保证业务的传送质量．从而降低每Bit的传输成本．是影响各运营商能否在竞争中胜出的重要因数。适应分组业务为主的承载需求,中国移动采用分组交换为内核的PTN网络来承载3G．LTE和以太网专线等分组业务。不同的业务对承载网提出不同的需求．譬如时延特性和带宽特性等。在PTN网络部署中．我们能够通过什么样的精细化流量管控技术来满足这些需求呢？     

分级指导随机提早丢弃队列管理机制CGRED

本文提出的分级指导随机提早丢弃CGRED是在因特网上为用户提供有区别服务的单队列管理机制,它同时满足了对服务质量的精细控制和实现简单性两方面的需求.CGRED采用在线测量的方法跟踪业务类的实际带宽占用情况,根据给定的优先级关系确定调整业务类的指导策略,并以采用自适应算法计算得到的丢弃指导概率作为分组丢弃概率的边界,成功地解决了将不同业务类的实际带宽占用情况转化成如何丢弃不同业务类分组的实际操作.仿真结果表明CGRED是一种能有效提供DiffServ的实用网络控制机制.     

Service based CAC with QoS guarantee in mobile wireless cellular networks

The increasing variety and complexity of traffic in today's mobile wireless networks means that there are more restrictions placed on a network in order to guarantee the individual requirements of the different traffic types and users. Call admission control (CAC) plays a vital role in achieving this. In this paper, we propose a CAC scheme for multiple service systems where the predicted call usage of each service is used to make the admission decision. Our scheme enables real‐time traffic to be transmitted using shared bandwidth without quality of service (QoS) requirements being exceeded. This ensures that the utilization of the available wireless bandwidth is maximized. Information about the channel usage of each service is used to estimate the capacity of the cell in terms of the number of users that can achieve a certain bit error rate (BER). Priorities assigned to each service are used to allocate the network capacity. An expression for the handoff dropping probability is derived, and the maximum acceptance rate for each service that results in the estimated dropping probability not exceeding its QoS requirements is calculated. Each call is then accepted with equal probability throughout the duration of a control period. Achieved QoS during the previous control period is used to update the new call acceptance rates thus ensuring the dropping probability remains below the specified threshold. Simulations conducted in a wideband CDMA environment with conversational, streaming, interactive and background sources show that the proposed CAC can successfully meet the hard restraint on the dropping probability and guarantee the required BER for multiple services. Copyright © 2005 John Wiley & Sons, Ltd.     

Performance Analysis of WiMAX Networks AC

In WiMAX networks, contention based bandwidth requests are allowed in the uplink channel on the time division duplexing frame. The standard allows some types of traffic classes to use this period while preventing others like Unsolicited Grant Service. In this study, we provide a performance analysis of the three types of connections (ertPS, non-real time Polling Service and Best Effort) that are allowed to contend for bandwidth request opportunities. The choice of these traffic classes covers both real and non-real traffic types. Two quality of service parameters; contention probability and average connection delay are investigated in order to evaluate the network performances. Different levels of priority and blocking probability are assigned to each class of service. This performance analysis has been done using an analytical model for evaluating admission control for the previous mentioned classes in WiMAX network.     

Source time scale and optimal buffer/bandwidth tradeoff forheterogeneous regulated traffic in a network node

We study the problem of resource allocation and control for a network node with regulated traffic. Both guaranteed lossless service and statistical service with small loss probability are considered. We investigate the relationship between source characteristics and the buffer/bandwidth tradeoff under both services. Our contributions are the following. For guaranteed lossless service, we find that the optimal resource allocation scheme suggests that sources sharing a network node with finite bandwidth and buffer space divide into groups according to time scales defined by their leaky-bucket parameters. This time-scale separation determines the manner by which the buffer and bandwidth resources at the network node are shared among the sources. For statistical service with a small loss probability, we present a new approach for estimating the loss probability in a shared buffer multiplexer using the “extremal” on-off, periodic sources. Under this approach, the optimal resource allocation for statistical service is achieved by maximizing both the benefits of buffering sharing and bandwidth sharing. The optimal buffer/bandwidth tradeoff is again determined by a time-scale separation     

A Novel Probability-Based Handoff Strategy for Multimedia LEO Satellite Communications

A novel bandwidth allocation strategy and a connection admission control technique arc proposed to improve the utilization of network resource and provide the network with better quality of service （QoS） guarantees in multimedia low earth orbit （LEO） satellite networks. Our connection admission control scheme, we call the probability based dynamic channel reservation strategy （PDR）, dynamically reserves bandwidth for real-time services based on their handoff probability. And the reserved bandwidth for real-time handoff connection can also be used by new connections under a certain probability determined by the mobility characteristics and bandwidth usage of the system. Simulation results show that our scheme not only lowers the call dropping probability （CDP） for Class I real-time service but also maintains the call blocking probability （CBP） to certain degree. Consequently, the scheme can offer very low CDP for rcal-time connections while keeping resource utilization high.     

Class-Based Service Connectivity Using Multi-level Bandwidth Adaptation in Multimedia Wireless Networks

Due to the fact that quality of service requirements are not very strict for all traffic types, more calls of higher priority can be accommodated by reducing some bandwidth allocation for the bandwidth adaptive calls. The bandwidth adaptation to accept a higher priority call is more than that of a lower priority call. Therefore, the multi-level bandwidth adaptation technique improves the overall forced call termination probability as well as provides priority of the traffic classes in terms of call blocking probability without reducing the bandwidth utilization. We propose a novel bandwidth adaptation model that releases multi-level of bandwidth from the existing multimedia traffic calls. The amount of released bandwidth is decided based on the priority of the requesting traffic calls and the number of existing bandwidth adaptive calls. This prioritization of traffic classes does not reduce the bandwidth utilization. Moreover, our scheme reduces the overall forced call termination probability significantly. The proposed scheme is modeled using the Markov Chain. The numerical results show that the proposed scheme is able to provide negligible handover call dropping probability as well as significantly reduced new call blocking probability of higher priority calls without increasing the overall forced call termination probability.     

Call admission control for voice/data integration, in.broadband, wireless networks

This paper addresses bandwidth allocation for an integrated voice/data broadband mobile wireless network. Specifically, we propose a new admission control scheme called EFGC, which is an extension of the well-known fractional guard channel scheme proposed for cellular networks supporting voice traffic. The main idea is to use two acceptance ratios, one for voice calls and the other for data calls in order to maintain the proportional service quality for voice and data traffic while guaranteeing a target handoff failure probability for voice calls. We describe two variations of the proposed scheme: EFGC-REST, a conservative approach which aims at preserving the proportional service quality by sacrificing the bandwidth utilization, and EFGC-UTIL, a greedy approach which achieves higher bandwidth utilization at the expense of increasing the handoff failure probability for voice calls. Extensive simulation results show that our schemes satisfy the hard constraints on handoff failure probability and service differentiation while maintaining a high bandwidth utilization.     

Credit-based processor sharing for decoupled delay and bandwidthallocation

We propose a credit-based processor sharing (CPS) approach for decoupled allocation of delay and bandwidth. For bandwidth guarantees, a CPS system serves traffic flows in proportion to their service weights. For delay guarantees, on the other hand, a CPS system allows real-time flows to temporarily borrow bandwidth from nonreal-time flows using service credits. This borrowing mechanism boosts the delay performance of real-time flows without increasing their long-term bandwidth requirements. By systematically regulating service credits of real-time flows, nonreal-time flows are protected for their aggregate long-term bandwidth share     

Enabling seamless multimedia wireless access through QoS‐based bandwidth adaptation

Effective support of real‐time multimedia applications in wireless access networks, viz. cellular networks and wireless LANs, requires a dynamic bandwidth adaptation framework where the bandwidth of an ongoing call is continuously monitored and adjusted. Since bandwidth is a scarce resource in wireless networking, it needs to be carefully allocated amidst competing connections with different Quality of Service (QoS) requirements. In this paper, we propose a new framework called QoS‐adaptive multimedia wireless access (QoS‐AMWA) for supporting heterogeneous traffic with different QoS requirements in wireless cellular networks. The QoS‐AMWA framework combines the following components: (i) a threshold‐based bandwidth allocation policy that gives priority to handoff calls over new calls and prioritizes between different classes of handoff calls by assigning a threshold to each class, (ii) an efficient threshold‐type connection admission control algorithm, and (iii) a bandwidth adaptation algorithm that dynamically adjusts the bandwidth of an ongoing multimedia call to minimize the number of calls receiving lower bandwidth than the requested. The framework can be modeled as a multi‐dimensional Markov chain, and therefore, a product‐form solution is provided. The QoS metrics—new call blocking probability (NCBP), handoff call dropping probability (HCDB), and degradation probability (DP)—are derived. The analytical results are supported by simulation and show that this work improves the service quality by minimizing the handoff call dropping probability and maintaining the bandwidth utilization efficiently. Copyright © 2006 John Wiley & Sons, Ltd.