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.     

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.     

TDMA时隙分配对业务时延性能的影响分析

 在TDMA通信系统中,时隙分配是影响业务时延性能的重要因素,包括时隙数量分配(带宽分配)、时隙分配周期(TDMA帧长)和时隙位置分配三方面.本文针对可变速率和固定速率两类业务,基于随机服务系统理论和交通流理论建立了业务时延模型,得到了平均时延的解析式,分析了时隙数量、时隙位置和TDMA帧长度对业务时延影响的规律和特点.结果表明时隙位置分配越均匀,越能改善业务的平均时延和时延抖动性能;而在传统的时隙连续分配方式下,增加时隙数量分配对时延性能提高非常有限.在DVB-RCS卫星系统等具有较长帧设计的TDMA系统中,采用时隙均匀分配方式能够有效提高业务时延性能.计算机仿真验证了建模分析的正确性.     

一种保证EPON中DBA公平性的算法

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.     

EPON中一种改进的动态带宽分配算法的设计

动态带宽分配是EPON系统的关键技术之一.文章首先分析了一种基于IPACT的RR算法的,然后提出一种有效的动态带宽分配算法MLQF.仿真试验表明,当网络负载很大时,MLQF算法在平均包延时和平均队列长度方面的性能均要优于已有的RR算法.     

在工业网中EPON的DBA算法研究

EPON系统中,上行数据传输的动态带宽分配（DBA）算法是关键技术之一。针对EPON在工业网络通信中的应用,对现有的DBA算法进行了分析和改进,以保证监控和报警等特殊业务的实时送达,消除交叉轮询的带宽浪费,并对该算法进行了仿真实验。仿真结果表明,该算法的带宽利用率高,业务时延抖动低,并且在低负载时无轻载惩罚现象。     

基于动态资源分配的EPON接入网研究

本文对基于动态资源分配的EPON结构进行了研究.在下行方向讨论了一种新的动态波分复用技术,并与时分复用广播系统相比较进行了仿真性能分析;在上行方向,采用时分多址技术共享上行带宽,对带宽分配策略进行了较深入研究,并进行了仿真分析.     

EPON上行信道中的动态带宽分配算法研究

传统的EPON系统的上行动态带宽分配方案是类似于IPACT的基于时隙长度分配的,这样虽然使上行信道得到了充分的利用,但是由于包延迟变化较大,不适合实时业务的传送.文章提出了一种多级授权分离发送动态带宽分配算法,它可以为不同业务提供不同的服务质量,既满足了实时业务的需要,又在一定程度上提升了网络的利用率.通过仿真测试,发现这种算法均有良好的时延特性和较稳定的队列尺度,能较好地支持多业务优先级的EPON系统.     

EPON系统中MAC算法的仿真设计

在分析EPON系统中MAC协议和算法的基础上进行了数学建模及仿真实验,提出了基于OLT的带宽分配算法.该算法可充分使用EPON的带宽资源,为在EPON的MAC层设计上提供了参考.     

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。     

Performance Evaluation of Ethernet Frame Burst Mode in EPON Downstream Link

We apply IEEE 802.3 frame burst mode (FBM) to the Ethernet passive optical network (EPON) downstream link and compare its performance with non‐frame burst mode for various traffic patterns. Although in light traffic loads (ρ<0.5) the efficiency of the FBM mechanism is not significant, it does feature high throughput, small jitter, low queue occupancy, and short queuing delay in optical line terminals under various traffic loads with various numbers of optical network units (ONUs). The FBM performance always approaches that of full‐duplex mode, especially under heavy traffic loads (ρ>0.5). Moreover, an increase in number of ONUs will decrease the burst performance. Our work shows that FBM scheme is very useful for EPON transmission and has low design complexity.     

EPON专用芯片设计

文章介绍了集成化设计以太网无源光网络(EPON)产品中传输汇聚(TC)子层芯片的结构设计框图,详细介绍了光线路终端(OLT)和光网络单元(ONU)的TC子层芯片设计.在此结构框架下,对EPON系统性能进行了仿真,发现在相同业务负载的情况下,EPON系统业务延迟小于以ATM为基础的无源光网络(ATM PON)系统中的相应延迟.     

千兆以太网无源光网络(EPON)的物理层研究

EPON是基于以太网技术的宽带接入系统，采用以太网的帧结构，在传统以太网的点到点和共享（多点到多点）媒体访问机制基础上，增加了一种点到多点的媒体访问机制，即无源光网络媒体，因而EPON在物理媒质参数、编／解码和串行／解串，上行突发通信等方面引出了较为复杂的问题，文章在详细阐述了千兆以太网物理层结构的基础上，深入探讨了上述EOON系统中的物理层问题，并给出了相应的解决方法。     

Experimental demonstration of an improved EPON architecture using OFDMA for bandwidth scalable LAN emulation

We propose and demonstrate an improved Ethernet passive optical network (EPON) architecture supporting bandwidth-scalable physical layer local area network (LAN) emulation. Due to the use of orthogonal frequency division multiple access (OFDMA) technology for the LAN traffic transmission, there is no need to change the existing EPON architecture. Only one receiver at each optical network unit (ONU) is required to detect both LAN traffic and EPON downstream traffic, which makes the proposed system simple and cost-effective. Moreover, flexible assignment of LAN traffic bandwidth is realized by allocating different number of subcarriers or using different modulation formats. The 250 Mb/s 4-quadrature amplitude modulation (4-QAM) and 500 Mb/s 16-QAM OFDM LAN traffic are successfully emulated with the EPON traffic in our experiment.     

基于EPON的可控组播技术

以太无源光网络( EPON)作为光纤到户的理想解决方案之一,凭借其带宽优势非常适合承载组播业务.EPON可控组播技术结合EPON的特点,从安全性和可维护性考虑,提出了一套可控组播实现方案,包括组播源管理、用户认证和组播流量控制等内容,以满足组播业务可维、可控的运营管理需要.     

Approximate performance analysis and simulation study forvariable-channel-per-burst SS-TDMA

An analysis is presented of the traffic performance of a variable-channel-per-burst (VCPB) satellite-switched time-division multiple access (SS-TDMA) that dynamically reconfigures traffic bursts. An SS-TDMA system with an onboard baseband switch is used as the VCPB application system. Bursts are assigned to each earth station one-by-one. Idle channels of other bursts are transferred to a burst having an insufficient number of idle channels by reconfiguration on a call-by-call basis. The VCPB is suited to SS-TDMA systems with relatively few earth stations. VCPB traffic performance depends on the reconfiguration strategy. The effects on traffic performance caused by reallotting idle channels to all bursts in every reconfiguration are described. An approximate formula for the reconfiguration probability from the loss probability of fixed-channel-per-burst TDMA weighted by the binomial distribution for the number of channels in each burst is derived     

Iterative resource pooling for bandwidth allocation in TDM-PON: algorithm, convergence and experimental evaluation

In this paper, we propose a new dynamic bandwidth allocation technique, SLIding Cycle Time (SLICT) for TDM-PON, specifically focused on ethernet passive optical network (EPON). Based on the sliding cycle time constraint, the proposed algorithm guarantees the maximum polling interval, an essential property for delay-sensitive applications and interactive services. We then introduce an iterative resource pooling that processes bursty best-effort traffic and achieves high throughput even under non-uniform upstream traffic distribution. We prove that greedy iterative resource pooling converges to equal resource allocation exponentially fast. Extensive numerical simulations show that SLICT outperforms existing techniques in all aspects: throughput, delay, packet loss and average queue size. Finally, SLICT has been implemented on an EPON FPGA board and the performance is confirmed under real traffic.     

Delay performance of some scheduling strategies in an input queuingATM switch with multiclass bursty traffic

Considers an N×N nonblocking, space division, input queuing ATM cell switch, and a class of Markovian models for cell arrivals on each of its inputs. The traffic at each input comprises geometrically distributed bursts of cells, each burst destined for a particular output. The inputs differ in the burstiness of the offered traffic, with burstiness being characterized in terms of the average burst length. We analyze burst delays where some inputs receive traffic with low burstiness and others receive traffic with higher burstiness. Three policies for head-of-the-line contention resolution are studied: two static priority policies [shorter-expected-burst-length-first (SEBF), longer-expected-burst-length-first (LEBF)] and random selection (RS). Direct queuing analysis is used to obtain approximations for asymptotic high and low priority mean burst delays with the priority policies. Simulation is used for obtaining mean burst delays for finite N and for the random selection policy. As the traffic burstiness increases, the asymptotic analysis can serve as a good approximation only for large switch sizes. Qualitative performance comparisons based on the asymptotic analysis are, however, found to continue to hold for finite switch sizes. It is found that the SEBF policy yields the best delay performance over a wide range of loads, while RS lies in between. SEBF drastically reduces the delay of the less bursty traffic while only slightly increasing the delay of the more bursty traffic. LEBF causes severe degradation in the delay of less bursty traffic, while only marginally improving the delays of the more bursty traffic. RS can be an adequate compromise if there is no prior knowledge of input traffic burstiness     

基于PCC架构提升EPON话音服务质量的方法研究

PCC是实现智能管道的关键技术,基于PCC架构可以实现网络资源的控制与管理,提升网络的服务质量。EPON是基于以太网的光接入网技术,其数据业务流量的突发性及分布的不均衡性,影响话音通信的质量。本文提出了基于PCC架构构建EPON智能管道以提升EPON话音服务质量的解决方案,给出了基于PCC的EPON智能管道的网络架构,重点讨论了通过对EPON话音、数据及视频业务的策略控制提高EPON话音服务质量的方法。     

1.25Gb/s交流耦合突发模式接收机的设计与性能

随着宽带业务的发展及宽带技术的提高,EPON在接入网中的地位将更加重要.突发模式接收机是EPON的关键技术之一.设计并研制了一种交流耦合突发接收机,对其性能进行了测试,发现该接收机满足IEEE802.3ah规定的EPON标准,并且能够在第1比特恢复数据.