一种基于改进蚁群算法的光网络动态RWA机制

动态RWA(路由与波长分配)问题是智能光网络的核心问题.文章提出一种解决动态RWA问题的改进蚁群算法,在转移概率中加入了链路的空闲率作为约束条件,同时还引入了随机扰动防止搜索过早收敛于局部最优路径.仿真结果表明,改进算法与传统Dijkstra+ FF(首次命中)算法相比,可以显著降低阻塞率,提高资源利用率.     

波分复用光网中的一种新型波长分配算法

目前网络承载业务的趋势是以IP为中心的数据业务,从而促进了以WDM光网络向高速和宽带多波长的应用和普及,为了进一步提高网络的性能并提高资源利用率,出现了光网络控制面技术.路由选择与波长分配问题是WDM光传输网络控制面中非常重要的问题之一.目前实际应用最广泛的波长分配算法是First-Fir(FF)算法.本文基于FF算法,研究动态业务下波分复用光网络在固定选路下的波长分配问题,提出了一种新的波长分配启发式算法——Joint First Fit.计算机仿真试验表明,与常用的FF算法相比,该算法显著的降低了网络呼叫阻塞率,有利于提高网络资源的利用率.     

基于PCE的WSON光网络RWA分配策略与仿真

为了有效分配WSON光网络中的波长资源,提出了一种基于路径计算单元(Path Computation Element,PCE)的波长交换光网络(Wavelength-Switched Optical Network,WSON)路由与波长分配策略.该策略通过PCE建立波长资源冲突避免表,并由目的节点与PCE进行通信确认,避免资源竞争问题的发生.将该策略下的网络阻塞情况与FF算法、RF算法进行对比仿真,仿真结果表明运用该策略可以有效抑制波长预留冲突,大大降低网络阻塞率.     

基于强化学习的光传送网路由波长优化

针对光传送网中动态业务的路由和波长问题,提出一种基于强化学习的深度路由波长分配算法DeepRWA。算法基于软件定义网络架构,通过强化学习灵活地调整控制光传送网,实现光网络路由波长分配策略优化。针对路由选择问题,结合链路上的波长使用情况,使用A3C算法选择合适的路由,使得阻塞率最小;针对波长分配问题,使用首次命中算法选择波长。考虑阻塞率、资源利用率、策略熵、价值损失、运行时间及收敛速度等多个指标,利用14节点NSFNET网络拓扑仿真实验。结果表明:当信道中包含18个波长时,与传统KSP-FF算法相比,所提出的路由波长分配算法的阻塞率降低了0.06,资源利用率提高了0.02,但运行时间有增加;在波长数超过45以后,与传统KSP-FF算法相比,所提算法保持阻塞率和资源利用率的同时,运行时间开始降低;当信道中包含波长数为58时,与传统KSP-FF算法相比,所提算法运行时间减少了0.07 ms。由此可见,提出的算法使路由选择和波长分配得到了优化。     

一种提高光网络攻击容忍性的RWA算法研究

通过研究光网络中带内串扰攻击及其传播原理,在基于串扰攻击有限传播的模型之上,提出了一种限制串扰攻击传播的波长路由分配(Routing and Wavelength Assignment,RWA)算法.该算法把分配后能产生最小串扰攻击传播最大值(Crosstalk Attack Propagation Maximum,CAPM)的波长路由分配给新的光路请求,从而减少全网的潜在的攻击传播范围.仿真结果显示,与常用的首次命中(Fist-fit)RWA算法相比,该算法能显著降低全网的串扰攻击传播最大值,从而提高光网络的攻击容忍性.     

全光网络波长数优化设计

在 WDM全光网的波长数优化设计中 ,本文采用最长路径优先的波长分配策略对 Naohide Nagatsu等人提出的 WP优化方案进行了改进。改进后的方案比原 WP优化方案更加简洁 ,并且仍然能够达到原 WP优化方案的优化效果。     

一种支持区分业务的智能光网络RWA方法北大核心

针对差异化的用户QoS(服务质量)需求,提供支持区分业务的RWA(路由和波长分配)算法是光网络当前研究的重点。文章提出了一种改进的支持区分服务的智能光网络GWAS(分组波长分配策略),针对不同等级的业务采用动态可调整的波长分组方案以实现差异化QoS。仿真结果表明,GWAS方案可以保证高优业务比低优业务具有更好的性能:在每根光纤复用9波长和160波长情况下,Mesh与NSFNET网络中高优业务比低优业务的阻塞率在相同业务负荷下最大降低24%与18%和15%与10%。     

一种基于改进遗传算法的波长路由算法

WDM(波分复用)光网络中基于GA(遗传算法)的RWA(路由与波长分配)算法是目前最常见的算法,为了提高网络资源利用率并进一步降低阻塞率,提出了一种动态的、基于改进GA的DCMA-GA(双交叉变异自适应遗传算法),通过引入自适应交叉与变异概率机制来减少GA的复杂度并应用于波长分配子算法中。仿真结果表明,与经典算法Dijkstra+FF(首次命中)相比,新算法最大能降低50%的阻塞率,在波长分配方面可提高10%的性能,验证了新算法的有效性。     

适用于波长交换光网络（WSON）的波长旋转图模型设计

将网络虚拓扑链路及关联波长均匀分布到旋转球体的表面,建立了新型的波长交换光网络(WSON)的波长旋转图模型,并基于旋转图模型提出了路由波长分配(RWA)新策略及算法.仿真结果表明,每条链路的总波长数分别为4和8时,新策略算法的阻塞率平均降低5.03%和9.71%,资源利用率平均提高3.3%和1.54%.该模型用于解决具有波长转换能力的RWA问题效果明显.     

一种基于自适应蚁群算法的动态RWA算法

动态RWA(路由与波长分配)问题是智能光网络的核心问题,以蚁群算法为代表的启发式算法是解决此类问题的优选方案之一。文章提出一种基于ADACO(自适应蚁群优化)算法的RWA机制,针对信息素挥发系数ρ采取自适应策略,实现了对全局信息素更新态调节。理论分析和数值仿真结果表明,与Dijkstra+FF(首次命中)算法相比,改进的ADACO+FF算法可以有效地降低网络阻塞率,规则型Mesh网络和NSFNET(国家科学基金会网络)的阻塞率最高分别降低了0.3和0.2。     

Cooperative Distributed MAC Design for Cross-layer Link Adaptation of UWB WPAN Devices

In this paper, we propose an efficient resource reservation scheme using cross-layer link adaptation for Ultra Wide Band Wireless Personal Area Network with Distributed Medium Access Control (D-MAC). Since the WiMedia D-MAC supporting Distributed Reservation Protocol (DRP) scheme causes lots of conflicts due to failure of beacon detection in wireless channel environment, overall performances of the WiMedia D-MAC can be deteriorated. Therefore, we propose Relay DRP protocol with Relay Node Selection criterion, which makes a relay path to avoid DRP conflicts or harsh channel conditions through cross-layer link adaptation of cooperative relay transmission scheme and is compliant with the current WiMedia D-MAC protocol. Simulation results demonstrate performance improvements of the proposed method for throughput and energy consumption.     

Equal resource sharing scheduling for PCS data services

For high speed mobile communication applications, the data rate can be increased by using multiple channels (or time slots) instead of one channel. To reduce the high blocking rate of multiple channels assignment, flexible resource allocation strategies have been proposed. This paper proposes the Equal Resource Sharing Allocation scheme (ERSA scheme) for flexible resource allocation. The ERSA scheme dynamically averages the allocated resource to the call requests based on the number of calls in a base station. The scheme accommodates the maximum number of requests while providing acceptable quality to the admitted requests. We developed an analytic model to investigate the performance of ERSA, and conducted simulation experiments to validate the analytic model. We define satisfaction indication SI as the performance measurement of the resource allocation algorithm. The experiment results indicate that the ERSA scheme outperforms other resource allocation algorithms proposed in our previous study.     

一种基于拥塞等级划分的LTE-V资源碰撞避免机制

为了降低车联网（Long Term Evolution-Vehicle to Everything,LTE-V）终端间的相互干扰并提升通信的可靠性,提出通过资源分配和拥塞控制来解决资源碰撞的问题。依据信道忙率（Channel Busy Ratio,CBR）划分拥塞等级,融合资源分配与拥塞控制提出相应的方案,形成资源碰撞避免机制。为了减少重选资源时发生的碰撞,提出了资源重选竞争退避机制以降低重选带来的不确定性;针对拥塞导致的碰撞,改变调制编码策略从而优化资源占用。仿真结果表明,与标准中基于感知的半持续调度（Semi-persistent Scheduling,SPS）相比,所提出的机制在传输距离为300 m时可以实现0.85以上的数据包投递率,有效减少资源碰撞,提升传输可靠性。     

基于IEEE 1500的NoC资源节点Wrapper设计

为确保不同资源节点在NoC系统中可靠地工作,亟需构建有高效、统一的资源节点测试方案。通过分析资源节点的测试特征和方法,选择IEEE 1500 Wrapper的可测性设计方案,在目前设计方法不足的基础上,提出针对不同端口工作时序复杂程度不同的特征设计不同的WBR单元以提高测试效率。实验以LIFO资源节点为例验证了Wrapper测试的有效性,结果表明改进设计方法可减少的WRCK时钟数等于LIFO资源节点矢量数的10倍,因此应用改进的设计方法可有效缩减测试时间。     

FRR for latency reduction and QoS provisioning in OBS networks

We propose a forward resource reservation (FRR) scheme to reduce the data burst delay at edge nodes in optical burst switching (OBS) systems. We also explore algorithms to implement the various intrinsic features of the FRR scheme. Linear predictive filter (LPF)-based methods are investigated and demonstrated to be effective for dynamic burst-length prediction. An aggressive resource reservation algorithm is proposed to deliver a significant performance improvement with controllable bandwidth cost. By reserving resources in an aggressive manner, an FRR system can reduce both the signaling retransmission probability and the bandwidth wastage as compared with a system without the aggressive reservation. An FRR-based QoS strategy is also proposed to achieve burst delay differentiation for different classes of traffic. Theoretical analysis and simulation results verify the feasibility of the proposed algorithms and show that our FRR scheme yields a significant delay reduction for time-critical traffic without incurring a deleterious bandwidth overhead.     

Dynamic resource allocation in cloud download service

Cloud download service, as a new application which downloads the requested content offline and reserves it in cloud storage until users retrieve it, has recently become a trend attracting millions of users in China. In the face of the dilemma between the growth of download requests and the limitation of storage resource, the cloud servers have to design an efficient resource allocation scheme to enhance the utilization of storage as well as to satisfy users' needs like a short download time. When a user's churn behavior is considered as a Markov chain process, it is found that a proper allocation of download speed can optimize the storage resource utilization. Accordingly, two dynamic resource allocation schemes including a speed switching (SS) scheme and a speed increasing (SI) scheme are proposed. Both theoretical analysis and simulation results prove that our schemes can effectively reduce the consumption of storage resource and keep the download time short enough for a good user experience.     

多小区WiMAX资源分配研究

针对多小区WiMAX下行链路资源分配问题,本文通过建立符合实际应用场景的同道干扰模型,并考虑到功率和带宽对资源分配的影响,提出功率、带宽联合优化的多小区WiMAX资源分配策略。该策略基于系统和容量最大化、最小容量最大化以及发射总功率最低准则,把网络资源分配问题建模为不同的数学优化模型,并利用凸优化问题求解得到不同准则条件下带宽、功率分配的最优解。仿真结果表明,提出的资源分配方法可以保证资源分配的公平性、提高系统容量并降低功率消耗      

A partial-success-rate-based resource reservation scheme for slotted OBS networks

Optical burst switching (OBS) is a promising technology for next-generation optical networks. Slotted OBS is an improved version of OBS to reduce burst loss rate, in which wavelength channels are divided into time slots. Slotted OBS has an implicit and under-used property that resources for two bursts with the same source and the same destination are interchangeable. The property further means that resource for a long-distance burst can be partially used by a short-distance burst. In this paper, we utilize the property to design a resource reservation scheme for slotted OBS networks. The scheme reserves a batch of slots every time; the specific number of slots is calculated according to number of arrived bursts and partial success rate (a newly introduced conception in this paper) at each node. Simulation results show that the proposed scheme can get lower burst loss rate, comparing with the well-performing two-way signaling scheme.     

一种用于解决OBS网中资源竞争的新机制

综合考虑多种因素,对突发的偏置时间进行改进,提出了一种新的解决资源竞争并能提供服务质量(QoS)保证的机制.结合3种信道调度算法(LRU、FF和PS),对该机制进行了仿真,并与PPJET机制进行了对比,结果表明,在突发丢失方面该机制的性能明显优于后者.