Statistical real-time channels on multiaccess bus networks

Real-time communication with performance guarantees is expected to become an important and necessary feature of future computer networks. In this paper, we present a scheme which can provide real-time communication services with both absolute and statistical performance guarantees on multiaccess bus networks for given input traffic characteristics and performance requirements. The proposed scheme reserves network bandwidth for real-time connections according to their needs. It also allows for independent addition and deletion of real-time connections while preserving existing guarantees. Our extensive simulation results for motion video communication have shown the proposed scheme to outperform the other well-known schemes     

A scheduling discipline and admission control policy for xunet 2

Xunet 2 is a collaborative research program with a goal of understanding the fundamental issues in the performance of ATM networks. These networks are expected to carry a mixture of constant bit-rate traffic, variable bit-rate traffic and computer traffic spanning a wide range of performance requirements. This paper describes these service requirements and matches them with performance guarantees that can be provided by the scheduling discipline supported by an experimental ATM switch. The scheduler supports per-virtual-circuit queueing and several priorities of round robin service in order to segregate real-time and non-real-time traffic and provide fair sharing for bursty computer traffic. Detailed simulations show that real-time traffic can be efficiently integrated with non-real-time traffic using appropriate call admission policies and enhancements to traditional round robin scheduling. While the present study focuses on providing quality of service guarantees in the Xunet 2 network, the design of the scheduler and the call admission policies are relevant to ATM networks in general. On leave of: Indian Institute of Technology, Delhi, India     

基于MPEG视频流的动态带宽分配算法

ATM是兴起的宽带网标准,基于报文的视频正是宽带网上的一个典型应用.变位率视频的传输方法为恒定的视频质量提供了可能,但是在传输过程中,报文的丢失、延迟和延迟抖动等因素都会影响视频质量,因此有必要提供QoS保证.提出了两种新的在ATM网上进行MPEG视频传输的动态带宽分配算法,一种是动态计算算法,另一种是动态虚拟缓存算法.在这些算法中,根据允许的丢包率,动态地调整MPEG视频带宽以保证QoS.     

基于ATM单瓶颈节点模型的PID拥塞控制器设计

针对ATM单瓶颈节点网络模型，提出ABR业务拥塞控制方案，给出使系统闭环稳定PID参数应满足的约束条件。设置前馈环节以抑制带宽波动对缓冲区队列长度的影响。仿真结果表明，业务服务质量得到了保证，系统具有较好的动态性能。     

An adaptive scheme for admission control in ATM networks

This paper presents a real time front-end admission control scheme for ATM networks. A call management scheme which uses the burstiness associated with traffic sources in a heterogeneous ATM environment to effect dynamic assignment of bandwidth is presented. In the proposed scheme, call acceptance is based on an on-line evaluation of the upper bound on cell loss probability which is derived from the estimated distribution of the number of calls arriving. Using this scheme, the negotiated quality of service will be assured when there is no estimation error. The control mechanism is effective when the number of calls is large, and tolerates loose bandwidth enforcement and loose policing control. The proposed approach is very effective in the connection oriented transport of ATM networks where the decision to admit new traffic is based on the a priori knowledge of the state of the route taken by the traffic.     

ATM网络流量控制中的活动VC计算方法

ATM网络ABR业务流量控制是一种基于速率的流量控制机制。在ERICA算法的基础上,提出有效活动虚连接的计算方法,根据它们的活动度计算活动连接的有效数值,从而准确计算出处于活动状态的源端数,将未用带宽在ATM网络ABR连接之间公平且准确地进行分配,体现了Max-Min公平分配准则,能保证算法的高效性和带宽分配的公平性。     

First-order rate-based flow control with dynamic queue threshold for high-speed wide-area ATM networks

In this paper we present a new rate-based flow control scheme for ATM ABR services and analyze its performance. The proposed algorithm, which we refer to as first-order rate-based flow control (FRFC) is the most simple form of queue-length-based flow control. The asymptotic stability, the steady-state throughput, queue length and fairness, and the transient behavior are analyzed for the case of multiple connections with diverse round-trip delays. We also consider a novel approach to dynamically adjust a queue threshold in the FRFC according to the changes in the available bandwidth, and the arrival and departure of connections. Simulations show that the simple FRFC with dynamic queue threshold (DQT) effectively maintains high throughput, small loss and a desired fairness in these dynamic environments and is a promising solution for ABR flow control in ATM networks.     

An adaptive QoS guaranteeing MAC protocol for real-time traffic in TDMA-based wireless ATM networks

This paper presents a new media access control (MAC) protocol based on forward error control (FEC), which is appropriate for supporting real-time traffic with strict QoS requirements in wireless ATM networks. As the channel BER in wireless environments is very high and varying 10⁻⁵–10⁻², previous schemes that use powerful FEC have combated to overcome this noisy channel condition at the cost of valuable bandwidth. As most previous works have been dedicated to maximize the channel efficiency, they were not able to meet QoS requirements of real-time applications in wireless networks. A new MAC protocol proposed in this paper is designed to guarantee the throughput requested by a real-time traffic user while keeping the bandwidth consumption at a minimum. The proposed scheme is for a TDMA system and uses adaptive FEC. We analyze the wireless channel and model it as a two-state error control system to design an efficient MAC protocol. We use simulation experiments to show how the proposed scheme provides QoS guarantees, and compare it with the CDMA system in terms of capacity, i.e. the number of users that can be supported.     

ATM网络的话音、数据混合接入系统

提出了一种利用ATM网络高效传输话音与数据业务的混合接入系统.该系统采用数字语音插空(DSI)技术对话音业务进行压缩,利用自适应带宽分配技术保证话音业务的时延和信元丢失率要求,并且充分利用线路资源进行话音与数据业务的综合传输,在保证不同类型业务QoS的条件下,提高了线路的利用率.     

Smith's principle for congestion control in high-speed datanetworks

In high-speed communication networks, large propagation delays could have an adverse impact on the stability of feedback control algorithms. In this paper, the classical control theory and Smith's principle are exploited to design an algorithm for controlling “best effort” traffic in high-speed asynchronous transfer mode (ATM) networks. The designed algorithm guarantees the stability of network queues, along with the fair and full utilization of network links, in a realistic traffic scenario in which multiple available bit rate connections, with different propagation delays, share the network with high priority traffic     

Connection Rerouting for Wireless ATM Networks

Wireless ATM (Asynchronous Transfer Mode) is an emerging technology designed to provide multimedia and other Quality of Service-oriented applications to mobile users by extending ATM connections to involve wireless links. The use of wireless ATM has also been motivated by an increasing deployment of ATM technology in backbone networks and also due to the need to support emerging services in the next generation (broadband) wireless networks, both terrestrial and satellite based. Since ATM was originally designed for high bandwidth and low error rate environment to support stationary users, the use of ATM in wireless environment raises many interesting issues. These include managing end-to-end ATM connection (using connection re-routing), maintaining location information about users as they move, supporting transmission of ATM cells over wireless links, and supporting quality of service )QoS( requirements in limited bandwidth environment. As users move, the end-to-end ATM connections need to be rerouted to support continued communications. The design of such rerouting schemes has recently received some consideration in literature, however many important issues including support for multicast and overhead requirements have not been fully addressed. In this paper, we present a detailed treatment of connection rerouting issues, design and performance evaluation of two rerouting schemes, and the support for multicast rerouting.     

Models for network design,servicing and monitoring of ATM networks based on the virtual path concept

Virtual Path (VP) concept has gained attention in terms of effective deployment of ATM networks for wide-area environment. In this paper, we present models and algorithms for network design and management of ATM networks based on virtual path concept from a network planning perspective. Our approach is based on statistical multiplexing of traffic within a traffic class by using a virtual path for the class and deterministic multiplexing of different virtual paths, and on providing dynamic bandwidth and reconfigurability through virtual path concept depending on traffic load during the course of the day. For some realistic example networks, we observe that considering network dynamism through variation of traffic during the course of a day by doing dynamic bandwidth and virtual path reconfiguration can save between 10 to 14% in network design costs compared to a static network based on maximum busy hour traffic.     

Quality-of-service management for multimedia streams with fixed arrival periods and variable frame sizes

Some types of multimedia streams, like compressed video, transmit frames of various sizes at fixed periodic instants. For such variable bit-rate streams, there is a trade-off between the transmission bandwidth reserved (and potentially unused) and the queueing delays observed. Moreover, the calculation of quality-of-service (QOS) guarantees is not trivial. The purpose of this paper is twofold. First, we present a QOS management scheme that maps variable bit-rate streams to a simple, periodic traffic model and thus allows for the estimation of delay bounds. The approach also includes a tuning parameter that explicitly controls the trade-off between reserved bandwidth and delay. Second, the scheme is applied to some real-world scenarios. Its validity is proven and hints for the practical control of the trade-off are derived.     

无线ATM通信网的越区切换控制

论文研究无线ATM通信网的越区切换控制问题,提出不同的业务类型应采用不同的切换控制方法,从而使多媒体业务的服务质量(QoS)在越区切换时仍然可以得到保证。文中着重讨论了由于无线ATM通信的特点所引起的路由重建、QoS的保证与协商,信元次序的保证等关键问题,并提出了相应的解决办法。     

A proportional feedback scheme for ATM networks

Available bit rate (ABR) service class is proposed by Asynchronous Transfer Mode (ATM) Forum to provide the “best-effort” services like traditional TCP/IP traffic. It is designed to make use of the remaining bandwidth not used by VBR and CBR. However, the bursty nature of ABR traffic makes it difficult to prevent buffers on ATM switches from overflowing. A number of schemes have been proposed for ABR traffic control. In this paper, a proportional scheme that is rate-based hop-by-hop flow control is proposed. A mathematical model is built to analyze the hop-by-hop flow control scheme. It is shown the scheme can utilize full bandwidth without any cell loss. It is also shown the scheme has low queuing delay and fast transient response.     

An Admission Control Scheme Based on Online Measurement for VBR Video Streams Over Wireless Home Networks

This paper presents an online measurement-based admission control scheme on the basis that the aggregate VBR video traffic is lognormally distributed. The proposed scheme consists of two components: measurement process and admission decision. The measurement process applies a linear Kalman filter to estimate statistical parameters of aggregate VBR video traffic. The estimated statistical parameters are used to calculate the effective bandwidth for admission decision. Variable bit rate (VBR) video traffic with high data rate is expected to occupy a dominant proportion of bandwidth for future wireless broadband home networks. To guarantee quality-of-service (QoS) of such VBR video streams, while achieving a high level of channel utilization, an efficient admission control scheme is urgently required, especially for emerging wireless multimedia indoor services, such as HDTV, online video game, etc. The proposed scheme is computationally efficient and accurate without much prior traffic information. Simulation results verify its effectiveness and show that it performs well for both a small number of connections and a large number of connections.     

Optimization for adaptive bandwidth reservation in wireless multimedia networks

In future wireless multimedia networks, user mobility management for seamless connection regarding realtime multimedia applications is one of the most important problems. In this paper we propose an opportunity-cost concept-based approach for adaptive bandwidth reservation with admission control for handover calls utilizing network traffic information. Excessive reservation guarantees low blocking probability of handover calls at the cost of high blocking probability of new calls. According to our survey, however, it may degrade bandwidth utilization while no prioritization for handover admissions degrades quality of service (QoS) for ongoing calls. We consider both QoS assurance and bandwidth utilization in order to optimize the amount of bandwidth to reserve for handover admissions. We believe that our scheme could be utilized as a guideline for cost-effective radio resource allocation in mobile multimedia networks.     

An improved scheme for self-healing in ATM networks

Broadband networks based on ATM technology can carry a large volume of data and can support diverse services like audio, video, and data uniformly. The reliability and availability levels provided by such networks should be very high. Self-healing is an elegant concept in this direction to provide highly reliable networks. A self-healing network can detect failures such as link/node failures and reroute the failed connections automatically using distributed control mechanisms. In this paper, we consider link and node failures including the VP terminating nodes unlike Kawamura and Tokizawa (Self-healing in ATM networks based on virtual path concept, IEEE Journal on Selected Areas in Communications 12 (1) (1994) 120–127). We present here an improved scheme for self-healing in ATM networks based on the concept of backup VPs. The problems we address are: (i) self-healing scheme; and (ii) backup VP routing. Two issues are addressed in the self-healing scheme: (i) backup VP activation protocol; and (ii) dynamic backup VP routing. We propose a new backup VP activation protocol which uses a VC packing strategy which allows the fast and prioritized restoration of critical VCs that were carried by failed VPs. We also propose a distributed dynamic backup VP routing algorithm which reduces the resource contention that may occur when multiple source–destination pairs contend for the routes simultaneously. The objective of the backup VP routing problem is to find a backup VP for each of the working VPs so that the cost of providing the backup is minimized. We propose a heuristic based solution for the backup VP routing problem using the concept of minimum cost shortest paths. We conducted simulation experiments to evaluate the performance of the proposed schemes. The results show that the proposed schemes are effective. Comparison of the results with those of the earlier schemes (R. Kawamura, I. Tokizawa, Self-healing in ATM networks based on virtual path concept, IEEE Journal on Selected Areas in Communications 12 (1) (1994) 120–127; C.J. Hou, Design of a fast restoration mechanism for virtual path-based ATM networks, Proceedings of IEEE INFOCOM’97, Kobe, Japan, April 1997) shows that the proposed schemes perform better.     

无线多媒体网络中一种基于测量网络状态的动态呼叫接纳控制算法

提出了一种无线多媒体网络中基于测量网络状态的动态呼叫接纳控制算法.它区分了实时和非实时业务,在网络带宽资源不足时可通过降低非实时业务带宽确保实时业务呼叫连接的可靠性;还可根据当前网络状况调整预留带宽大小,使小区实时业务切换呼叫掉线率低于设定的门限值.大量仿真结果显示该算法具有低实时业务切换呼叫掉线率和与固定预留方案相当的带宽利用率,而只以略高的新呼叫阻塞率为代价,适合各种不同概率发生时实际应用的情况.     

Fast,Fair and Frugal Bandwidth Allocation in ATM Networks

Abstract. ATM networks are used to carry a variety of types of traffic. For some types of traffic, in particular Available Bit Rate (ABR) traffic, the bandwidth of a network is typically insufficient to satisfy the requests of all the sessions, and so some fair allocation scheme must be devised. The ATM Forum, the standards setting body for ATM networks, has specified that the fairness criterion for ABR traffic should be Max-Min Fairness , which intuitively means that raising the bandwidth of any session comes at the expense of some other session of no greater bandwidth. Protocols to allocate bandwidth to sessions in a max-min fair manner are an important part of a network design. For a protocol to be realistic, it must conform to the Resource Management (RM) cell mechanism specified by the ATM Forum. Such RM cells get sent as a constant fraction of all cells sent by the source; however, they have only a few fields. RM cells are the only means of communication allowed from link to link so any reasonable protocol is totally distributed and asynchronous, since the RM cell mechanism does not easily lend itself to synchronization. Finally, RM Cells must be handled very quickly at each link. We call a protocol frugal if at each link it performs O(1) computation per RM cell and uses O(1) space per session. Recently, several frugal RM cell protocols have been proposed for ABR traffic, but none have been shown to converge to the max-min fair state. Protocols that are known to converge in a linear number of maximum round-trip times require RM cell processing that is linear in the number of sessions that go through a link. In this paper we give a frugal RM cell protocol for ABR that matches the convergence time of the fastest known non-frugal protocol. A second type of ABR traffic is the Minimum Cell Rate (MCR) type, where every session can specify a minimum amount of bandwidth. The max-min fair allocation should then respect these MCR requests. We extend our results to give the first frugal RM cell protocol for MCR and achieve a quadratic convergence rate.