共查询到19条相似文献,搜索用时 140 毫秒
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提出了一种利用模糊控制技术的ATM网络混合业务流动态带宽分配方案。讨论了方案的基本思想,模糊参数的选取,模糊控制规则设定及其调整过程和实现步骤。并通过计算机仿真详细讨论了业务类型为VBR的语音图像信源和业务类型为ABR的数据信源作为混合业务流时其信元的时延、丢失、抖动等服务质量指标与该方案中主要设计参数之间的关系。 相似文献
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本文给出了一种支持多优先级业务的带宽分配算法。其中高优先级业务固定带宽分配和低优先级业务动态带宽分配,将上行帧分为第一时隙和第二时隙两部分,各ONU高优先级业务在上行第一时隙发送,第二时隙用于低优先级业务,同时采用固定周期的带宽分配方案,因此降低了高优先级业务的时延和时延抖动。通过ONU实行内部调度并且参与上行接入计算,避免了上行复杂的同步问题,提高了链路利用率。 相似文献
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IDC流量计费是为了适应IDC业务飞速发展而推出的一种基于流量采集的带宽租用费率体系.它包括平均流量计费和峰值流量计费两大类计费方式,能够灵活适应各个层次、各个行业用户的带宽诉求,达到用户和运营商的利益双赢.ID C流量计费采用SNMP协议作为底层采集手段,通过MRTG和TTServer实现业务逻辑,未来IDC流量计费将向精细化管理方向迈进. 相似文献
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张晓京 《电信工程技术与标准化》2011,24(2):66-70
数据业务实时计费信息的采集方案是实现在线计费的关键基础功能.考虑到移动通信的特性,如何解决用户在漫游状态下使用业务的实时计费信息采集,成为采集方案实现过程中的技术关键点.本文通过分析在线计费的通用模型,给出了计费信息在业务平台产生后的两类采集方案.并对两类方案的优缺点进行了分析和比较. 相似文献
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根据光网络由SDH向分组化PTN网络演进及新兴流媒体业务的特点,本文采用混合业务流模型,引入门限控制,多级选择丢弃和多级缓存优先级的概念,提出了一种基于业务分类和业务优先级的带宽分配算法-基于门限的动态优先级带宽分配方案(TDPBA),克服了门限控制分配带宽颗粒过大和优先级算法运算量较大的弊病,在特别定制的试验平台上进行了四优先级系统的网络性能仿真,验证了此方案可以最大限度的保障高优先级业务的传输,可以用于对QoS有较高要求的业务,适合引入处在分组化进程中的光网络,在现有网络上更有效的承载流媒体业务. 相似文献
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The role of call admission control (CAC) in high-speed networks is to maintain the network utilization at a high level, while
ensuring that the quality of service (QoS) requirements of the individual calls are met. We use the term static CAC to describe
schemes that always allocate the same bandwidth to a specific group of multiplexed calls, independent of the other traffic
sharing the link. Dynamic CAC, on the other hand, denotes a scheme in which the bandwidth allocation to a group of calls sharing
a queue is influenced by the traffic in other queues destined for the same outgoing link. We propose a generic dynamic call
admission scheme for VBR and ABR traffic whose aim is to reduce the blocking rate for VBR calls at the expense of a higher
blocking rate for ABR calls. Our scheme is generic because it builds up on a pre-existing static scheme, e.g., one based on
a simple notion of effective bandwidth. Our simple approach results in a significant reduction of the blocking rate for VBR
traffic (several orders of magnitude), if the bandwidth requirements of a single call are a reasonably small fraction of the
link capacity. At the same time, the deterioration of service for ABR traffic can be contained.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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With the combination of telecommunication, entertainment and computer industries, computer networking is adopting a new method
called Asynchronous Transfer Mode (ATM) networking. Congestion control plays an important role in the effective and stable
operation of ATM networks. Traffic management concerns with the design of a set of mechanisms which ensure that the network
bandwidth, buffer and computational resources are efficiently utilized while meeting the various Quality of Service (QoS)
guarantees given to sources as part of a traffic contract. In this paper, the most widely recognized congestion control schemes
for ABR service are investigated. Some of these schemes show either lack of scalability or fairness while other well‐behaved
schemes may require a highly complex switch algorithm that is unsuitable for implementation in cell‐switching high‐speed ATM
networks. A new and improved congestion control scheme is proposed to support the best‐effort ABR traffic. This algorithm
provides the congestion avoidance ability with high throughput and low delay, in addition to achieving the max–min fairness
allocation.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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We propose a scheme for transmission of variable bit rate (VBR) compressed video for interactive applications using the explicit-rate congestion-control mechanisms proposed for the available bit rate (ABR) service in asynchronous transfer mode networks. Compressed video is inherently bursty, with rate fluctuations over both short and long time scales. This source behavior can be accommodated by the ABR service, since the explicit-rate scheme allows sources to request varying amounts of bandwidth over time. Moreover, when the bandwidth demand cannot be met, the network provides feedback indicating the bandwidth currently available to a connection. In our scheme, the video source rate is matched to the available bandwidth by modifying the quantization level used during compression. We use trace-driven simulations to examine how effective the enhanced explicit-rate scheme is in “rate matching” between the network and the source and the effect on end-to-end delay. We also look at the sensitivity of the proposed scheme to the estimates of the network round-trip times and to inaccuracies in the rate requests made by sources 相似文献
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Guaranteed quality-of-service wireless access to ATM networks 总被引:2,自引:0,他引:2
Cheng-Shang Chang Kwang-Cheng Chen Ming-Young You Jin-Fu Chang 《Selected Areas in Communications, IEEE Journal on》1997,15(1):106-118
We study the problem of wireless access to asynchronous transfer modes (ATMs). We consider three classes of ATM sources: constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR). We propose a polling scheme with nonpreemptive priority. Under such a scheme, we derive sufficient conditions such that all the CBR sources satisfy their jitter constraints and all the VBR sources satisfy their delay constraints. The remaining bandwidth is used by the ABR sources, for which we adapt a random access scheme proposed by Chen and Lee (1994). For this random access scheme, we derive the throughput-offer load characteristic, and thus the capacity. Based on this, we propose adaptive random access schemes that track the offer load to its optimal value. Our simulations show that our adaptive schemes maintain a high throughput with respect to the whole range of system load 相似文献
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W. Melody Moh Madhavi Hegde Niki Pissinou 《International Journal of Communication Systems》2000,13(1):1-28
Congestion control is very important for effective and stable operation of ATM (Asynchronous Transfer Mode) networks. Owing to the bursty and unpredictable characteristic of data network traffic, its congestion control is particularly a challenge for network researchers and designers. The ATM Forum has recently adopted rate‐based congestion control for ABR (Available Bit‐Rate) traffic which is the service class defined for data network applications. However, there is a number of congestion control schemes prevalent. ATM Forum has decided not to specify switch behaviour for ABR traffic; this has further introduced additional ambiguity. Consequently, an evaluation and comparison of the existing protocols would provide valuable guidance for network designers and engineers; it would also give insight for researchers to explore the essence of different congestion control schemes. In the first part of this paper, we investigate the effectiveness of ABR congestion control in the presence of bursty source traffic and the relationship between the burst time scale and the ABR control time scale. Two ABR congestion control schemes, the ABR Explicit Forward Congestion Indication (EFCI) and ABR Congestion Indication (CI) schemes, are compared with Unspecified Bit Rate (UBR) transport which makes no effort to control congestion. Traffic sources of various burst lengths of 100, 1000, 10000, and an equal mix of 100 and 10000 ATM cells are used in simulations. It is found that ABR congestion control schemes effectively control low frequency, medium to long‐term traffic load transients. This is further supported by the result of integrating TCP over ATM congestion control schemes included in the paper. ABR control schemes do not control high frequency, short‐term load transients well, but ABR control is not necessary in such cases since short‐term transients do not require a large amount of buffering. In the second part of this paper, we evaluate and compare six rate‐based congestion control protocols including Scheme I: EFCI, Scheme II: EFCI with separate RM queues, Scheme III: CI, Scheme IV: CI with separate RM queues, Scheme V: the CAPC2 ER (Explicit Rate), and Scheme VI: the EFCI with utilization‐based congestion indication. Each scheme is simulated and compared in the LAN, WAN, and GFC (General Fairness Configuration) environments specified by the ATM Forum. Effects of varying VC (Virtual Circuits) number and changing endsystem–switch distance has been investigated. Their fairness is also compared using the GFC configuration. We have found that ER control scheme performs significantly better than the other five binary control schemes by its faster response to congestion, smoother regulation of bit‐rates, lower queueing delay, shorter buffer queue length, and fairness. Among the other five schemes, the CI scheme performs better than the EFCI scheme. Providing separate RM queues has significantly improved the EFCI scheme in the WAN environment, but has little effect on the CI scheme. Link utilization‐based congestion detection has suffered from either low utilization or an excess cell loss which is unacceptable in most data applications. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Nikolas Mitrou Kimon Kontovasilis Emmanual Protonotarios 《Telecommunication Systems》1996,5(1):135-157
The Available Bit Rate (ABR) service is being designed as a low-cost transport service over ATM, which will be using the bandwidth left available after servicing connections of another, high-priority class. The implementation of the ABR service requires large buffers at each multiplexing/switching stage to keep cell-loss rates down to a minimum, and a feedback mechanism from the network to the terminals in order for the latter to adjust their traffic profiles according to the prevailing congestion conditions. Thus, an enhanced set of traffic control functions is necessary to support this new service. In this paper the main traffic analysis and control problems related with the ABR service are addressed, modelled and answered on the basis of effective rates defined for the multiplexed connections. Emphasis is given to a simple CAC scheme which consists in allocating peak rates to the high-priority class and effective rates to the ABR class. An adaptive shaping mechanism is then required to enforce the contracted effective rates for the ABR streams. Producing ON/OFF streams facilitates the control functions by allowing the use of approximate closedform calculations.This work has been carried out partly in the framework of the RACE EXPLOIT project. 相似文献
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Li-Shen Juhn Li-Ming Tseng 《Broadcasting, IEEE Transactions on》1998,44(2):182-185
As we support video-on-demand (VOD) service with batching schemes, the bandwidth requirement will be very large for a popular movie. For a hot video, fast data broadcasting scheme substantially reduce the bandwidth requirements as compared with batching schemes. However, the fast data broadcasting scheme needs to predict which movie is hot. If the prediction is not accurate, the allocated bandwidth will be wasted. This paper presents a new data broadcasting scheme for VOD service. For a movie, as it is popular, the new scheme will work like the fast data broadcasting scheme to save the communication bandwidth. If there is no request for the movie, the new scheme will not allocate bandwidth for the movie. Therefore, the bandwidth allocation for a movie is always efficient whether or not the movie is popular 相似文献
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Allan T. Andersen Søren Blaabjerg Gábor Fodor Miklós Telek 《Telecommunication Systems》2002,19(1):75-99
In this paper we consider an ATM transmission link, to which CBR or VBR and ABR or UBR calls arrive according to independent Poisson processes. CBR/VBR calls (characterized by their equivalent bandwidth) are blocked and leave the system if the available link capacity is less than required at the time of arrival. ABR/UBR calls, however, accept partial blocking, meaning that they may enter service even if the available capacity is less than the specified required peak bandwidth, but greater than the so called minimal accepted bandwidth. Partially blocked ABR/UBR calls instead experience longer service time, since smaller given bandwidth entails proportionally longer time spent in the system, as first suggested in [3] and analyzed in details herein. Throughout the life time of an ABR/UBR connection, its bandwidth consumption fluctuates in accordance with the current load on the link but always at the highest possible value up to their peak bandwidth (greedy sources). Additionally, if this minimal accepted bandwidth is unavailable at the time of arrival, ABR/UBR calls are allowed to wait in a finite queue. This system is modeled by a Continuous Time Markov Chain (CTMC) and the CBR/VBR and ABR/UBR blocking probabilities and the mean ABR/UBR waiting- and service times are derived. 相似文献