Topology design and bandwidth allocation in ATM nets

The design of a P/S network embedded into a backbone facility network is discussed. The problem is formulated as a network optimization problem where a congestion measure based on the average packet delay is minimized, subject to capacity constraints posed by the underlying facility trunks. The variables in this problem are the routing on the express pipes (i.e. the channels that interconnect the P/S modes) and the allocation of bandwidth to such pipes. An efficient algorithm is presented for the solution of the above problem and it is applied to some representative examples. It is shown that for some test cases the congestion measure is substantially reduced with respect to the values obtained when the embedded topology is kept identical to the backbone topology. Dynamic reconfiguration schemes where the embedded topology is periodically adjusted to track the fluctuations in traffic requirements are discussed     

Reservation-based bandwidth allocation in a radio ATM network

The comparative performance of a number of reservation-based bandwidth sharing policies that could be used to maximize the link utilization and/or offer equally fair or preferential treatment to a class of supported users, is examined in the context of a radio asynchronous transfer mode local-area network (ATM LAN). Our analytical results, based an a recursion for the link occupancy distribution originally suggested by Kaufman (1981) and Roberts (1981) independently and subsequently extended to include finite source population models, are further extended in the cases of equal sharing of the resources with retries, and a dynamic sharing mechanism in which, when the available capacity is exceeded, weighted reductions for the active users' rates and queueing are employed. Next, examining the application of the above sharing schemes in an indoor radio environment, we apply switched diversity and a Reed-Solomon-based forward error correction (FEC) scheme to recover radio-related (Rayleigh fading) packet losses. The performance and the effects of the fading-mitigating switched-antenna-diversity mechanism and the required on a packet-basis coding protection are taken into account in order to establish the actual radio link throughput under the above conditions     

Multiple access control with intelligent bandwidth allocation forwireless ATM networks

Two major challenges pertaining to wireless asynchronous transfer mode (ATM) networks are the design of multiple access control (MAC), and dynamic bandwidth allocation. While the former draws more attention, the latter has been considered nontrivial and remains mostly unresolved. We propose a new intelligent multiple access control system (IMACS) which includes a versatile MAC scheme augmented with dynamic bandwidth allocation, for wireless ATM networks. IMACS supports four types of traffic-CBR, VBR, ABR, and signaling control (SCR). It aims to efficiently satisfy their diverse quality-of-service (QoS) requirements while retaining maximal network throughput. IMACS is composed of three components: multiple access controller (MACER), traffic estimator/predictor (TEP), and intelligent bandwidth allocator (IBA). MACER employs a hybrid-mode TDMA scheme, in which its contention access is based on a new dynamic-tree-splitting (DTS) collision resolution algorithm parameterized by an optimal splitting depth (SD). TEP performs periodic estimation and on-line prediction of ABR self-similar traffic characteristics based on wavelet analysis and a neural-fuzzy technique. IBA is responsible for static bandwidth allocation for CBR/VBR traffic following a closed-form formula. In cooperation with TEP, IBA governs dynamic bandwidth allocation for ABR/SCR traffic through determining the optimal SD. The optimal SDs under various traffic conditions are postulated via experimental results, and then off-line constructed using a back propagation neural network (BPNN), being used on-line by IBA. Consequently, with dynamic bandwidth allocation, IMACS offers various QoS guarantees and maximizes network throughput irrelevant to traffic variation     

一种改进的GPON动态带宽分配策略

利用小波变换将自相似性网络流量的长相关性转化为短相关性,并预测流量的方法,对GPON系统物理媒质控制(MAC)层的关键技术--动态带宽分配(DBA)进行研究.在理论上对一种已有的DBA策略提出合理改进.     

EPON中节能动态带宽分配算法

结合光网络单元(ONU)休眠控制和动态带宽分配机制,提出一种节能的双向DBA算法。该算法根据上/下行业务量为每个ONU分配合适的上/下行授权带宽,保证每个ONU在上/下行方向都具有较低的传输时延,同时尽可能增加ONU的休眠时间来降低网络能耗。仿真结果表明,与已有算法相比,该算法具有较低的上/下行平均时延,并能减少ONU的能耗。     

GPON动态带宽分配算法研究

针对GPON系统动态带宽分配过程中存在的时延特性,将经过最小均方误差算法修正的线性预测模型引入基于T-CONT的周期轮询动态带宽分配算法中,通过预测每个T-CONT在等待时间内到达的数据流量,来提高ONO向OLT申请带宽的准确度,降低业务传输时延.最后利用OPNET软件对改进算法进行仿真验证,仿真结果表明引入预测机制后...     

一种公平的EPON动态带宽分配算法

提出一种EPON上行链路动态带宽分配算法一周期比例DBA。ONU基于多门限周期地上报带宽请求，OLT根据ONU的带宽请求及其合约带宽进行动态带宽分配。当多个ONU竞争系统带宽时，OLT按照ONU合约带宽的比例进行带宽分配。仿真结果表明：周期比例DBA算法在实现高带宽利用率的同时又具有良好的公平性。     

EPON中一种改进的动态带宽分配算法

对经典的EBA算法进行了改进,提出了一种有效地利用空闲时间(idle time)来传输数据的动态带宽分配算法--N-EBA算法.仿真结果表明,N-EBA算法具有良好的平均包时延和较高的带宽利用率.     

Predictive dynamic bandwidth allocation for efficient transport ofreal-time VBR video over ATM

This paper presents a novel approach to dynamic transmission bandwidth allocation for transport of real-time variable-bit-rate video in ATM networks. Video traffic statistics are measured in the frequency domain. The low-frequency signal captures the slow time-variation of consecutive scene changes while the high-frequency signal exhibits the feature of strong frame autocorrelation. Our queueing study indicates that the video transmission bandwidth in a finite-buffer system is essentially characterized by the low-frequency signal. We further observe in typical JPEG/MPEG video sequences that the time scale of video scene changes is in the range of a second or longer, which localizes the low-frequency video signal in a well-defined low-frequency band. Hence, in a network design it is feasible to implement dynamic allocation of video transmission bandwidth using on-line observation and prediction of scene changes. Two prediction schemes are examined: recursive least square method and time delay neural network method. A time delay neural network with low-complexity high-order architecture, called “pi-sigma network,” is successfully used to predict scene changes. The overall dynamic bandwidth-allocation scheme presented is shown to be promising and practically feasible in obtaining efficient transmission of real-time video traffic     

一种新的EPON上行动态带宽分配算法与仿真

为了合理分配EPON上行信道带宽,提出一种能够区分服务等级的固定周期轮询动态带宽分配算法.该算法将光网络单元(ONU)的业务分为三个等级,根据不同的业务等级动态分配上行带宽,有效保证整个EPON网络的QoS以及带宽分配的公平性.同时,为了进一步提高EPON系统上行链路的带宽利用率,克服算法产生的idle time问题,对算法进行了改进.最后,对该算法进行仿真实验.     

一种基于星上处理的卫星ATM网络动态带宽分配策略

本文提出了一种基于星上处理的卫星ATM网络的动态带宽分配方案,它通过对流量的估计动态申请带宽,卫星作为控制中心根据链路利用情况来分配带宽,仿真结果表明,相对于现有的的方法,它可以保持链路效率,提高业务的服务质量,同时这种方法对星上资源要求不高,易于实现。     

EPON和WLAN融合架构下带宽分配算法的研究

提出和设计了EPON和WLAN融合网络架构下两种上行链路调度算法:集中式带宽分配和分布式带宽分配,对它们的优缺点做了详细分析.理论和仿真实验表明,与集中式带宽分配相比较,分布式带宽分配算法能使融合网络高效运行,可以很好地支持各种业务的QoS,提高了系统吞吐量,降低了各业务的时延.     

Optimal bandwidth and buffer allocation method for heterogeneoustraffic with multiple QoS in ATM networks

An optimal bandwidth and buffer allocation scheme is proposed which maximises network utilisation and satisfies both cell loss rate (CLR) and delay requirements for heterogeneous traffic with multiple quality of service. Simulation results show that the proposed scheme satisfies CLR and delay requirements and also utilises network resources efficiently     

EPON轮询带宽分配算法初探

以Ethernet为基础的无源光网络（Ethernet-PON)是未来实现宽带,多业务综合接入的重要技术手段。本文分析了EPON统的基础结构和各个组成部分,实现系统所需要解决的关键技术及实现方法,同时对上行带宽分配的轮询算法进行了探讨。     

Dynamic signalling period allocation algorithm for wireless ATM MACprotocols

A control algorithm called DSPA (dynamic signalling period allocation) is presented which exploits information from mobile terminals for the dynamic allocation of signalling periods in wireless asynchronous transfer mode medium access control protocols. The algorithm increases allowable loads that guarantee quality of service, and maintains stable throughput even in the presence of variations in traffic     

WDM EPON中的动态波长带宽分配算法

基于WDM EPON系统结构和已有波长带宽分配算法(DWBA)的不足,提出了一种结合流量预测与预分配机制的动态波长带宽分配算法--DWBPA.仿真表明在不同网络负载情况下,该算法不仅保证了波长带宽分配的公平性,而且能够满足高优先级业务的延时要求.     

基于多重分形小波GPON带宽分配算法

当前吉比特无源光网络中动态带宽分配算法主要是基于轮询机制,该算法是OLT根据各个ONU发送请求带宽信息进行动态分配带宽,但该算法不能实时获取各个ONU的请求信息.由于GPON网络业务流量具有多重分形特性,因此可以通过多重分形小波对网络流量进行预测,得到ONU实时的带宽信息.文章将预测结果应用于GPON上行信道动态带宽分配,提出一种改进动态带宽分配算法.     

一种新的HomePNA网络动态带宽分配算法

基于同轴的家庭电话线网络联盟(HomePNA)3.0网络是一个上下行共享同一频段,使用同步媒体接入控制(SMAC)或异步媒体接入控制(AMAC)方式工作的系统.为保障视频、语音和数据等多业务的服务质量(QoS)特性,文章提出了一种新的动态带宽分配算法,即高优先级业务基于流的带宽预留和低优先级业务基于流量统计的上行带宽分配.给出了模型和仿真结果,证明了这种算法的正确性.     

混合TDM/WDM EPON中动态带宽分配算法

针对TDM EPON向WDM EPON升级过程中各个光网络单元(ONU)支持波长数不尽相同的特点,提出一种基于波长间负载均衡的动态带宽分配算法(LB-DBA).该算法在分配带宽时考虑波长信道的带宽约束,同时分两步确定授权给ONU的发送波长和发送时间,有利于波长信道间的负载均衡.仿真结果表明,LB-DBA可以避免已有算法在混合TDM/WDM EPON中可能出现的授权周期长度增加和资源利用率低等问题,有效改善网络性能.     

一种用于EPON的新型DBA算法

分析了经典轮询算法的优缺点,提出一种保证QoS的新型DBA算法--DGPRA(Divided-period Grant Partly Reaving Arithmetic,分周期授权部分抢占算法).该算法基于轮询的思想,从实用的角度为业务进行了分类,对三种不同的业务提出了新型处理策略:对语音业务预留带宽,对视频和数据业务细分循环周期,分级循环.同时,这种算法中还引入了新的抢占机制.仿真结果表明:该算法有良好的时延特性,特别有利于保证高级业务的QoS.