以太网无源光网络中的QoS研究

在分析以太网无源光网络系统MAC协议的基础上,研究基于QoS的动态带宽分配机制,提出一种新的支持业务的QoS的动态带宽分配算法。该算法采用限制性带宽分配方法和基于优先级的调度方式,基于业务的通信量特征对各类业务预分配传输带宽。仿真结果表明该算法在时延和吞吐量性能上优于现有算法。     

改进的神经网络EPON动态带宽分配方法

动态带宽分配（DBA）是EPON的关键技术,根据数据业务流量的突发性调整了ONU授权时隙的顺序,提出了一种改进的轮询算法,构造了微粒群（PSO）优化的神经网络预测模型,提高了轮询周期内ONU新增数据的预测精度,从而保证了带宽分配公平性。仿真结果表明,该算法在优化带宽资源分配、降低平均数据时延方面均优于传统DBA算法。     

多业务流量预测动态带宽分配方法

静态带宽资源分配方法或基于业务分类的动态带宽分配方法等很难适应业务流特性,无法保证各级业务的服务质量。设计了流量预测及带宽分配模型,给出了流量预测计算方法,提出多业务流量预测动态带宽分配方法（MSTPDBA）,该方法基于业务预测流量的大小进行可用带宽的重新分配。仿真实验证明了MSTPDBA的有效性,能控制不同业务的时延,并提高了系统带宽资源的利用率。     

基于角色控制的天基网带宽分配方法

针对天基综合信息网（SBN）稳定性比较差的缺点,提出一种基于角色控制的动态带宽分配算法（RCBA）,基站将服务连接的带宽请求按照优先级分类,在设定预留带宽的基础上允许抢占带宽。仿真实验表明,相比传统带宽分配算法,RCBA算法降低了时延,减少了丢包率,较好地满足了天基网的应用需求。     

Design and analysis of a frame-oriented dynamic bandwidth allocation scheme for triple-play services over EPONs

Ethernet Passive Optical Networks (EPONs) are regarded as an important technology for current access networks. However, EPONs perform poorly in differentiated service environments, and may therefore fail to meet the Quality of Service (QoS) demands of emerging triple-play services (i.e. Voice over IP, video and BE traffic). Accordingly, the present study proposes a novel Dynamic Bandwidth Allocation (DBA) scheme, designated as Frame-Oriented Interleaved Polling with Adaptive Cycle Time (FIPACT), to improve the differentiated QoS capability of EPON networks. In the proposed scheme, the Optical Line Terminal (OLT) divides the time domain of the upstream network bandwidth into a contiguous series of fixed-length frames. Within each frame, each Optical Network Unit (ONU) is guaranteed sufficient network resources to transmit a specific quota of each triple-play service. In this manner, the proposed DBA scheme can satisfy the differentiated QoS requirements of triple-play services. Therefore, based on the M/G/1 queueing analysis framework of multiuser cyclic polling systems, this study develops an analytical framework to derive the closed-form expressions for FIPACT mean packet delay. The simulation results validate the analytical results and confirm the efficiency and effectiveness of the proposed DBA scheme.     

一种面向业务的动态带宽分配方法

在分析传统QoS业务模型以及传统动态带宽分配方法（DBA）的基础上,提出一种面向业务的动态带宽分配算法。该算法吸取了各种QoS业务模型及传统动态带宽分配方法的优点,充分考虑了不同业务服务质量对带宽分配要求的差别以及带宽资源的利用率,仿真结果表明这种方法更加有效。     

一种分层多描述编码的动态带宽分配策略

针对无线流媒体业务带宽资源有限的特点,提出一种基于分层多描述编码的动态带宽分配策略LMDBA.该策略利用了分层多描述编码的特性实现动态带宽分配,并采用QoS升降级策略,在保证用户QoS的前提下,尽可能地降低系统阻塞,提高系统带宽资源利用率.并对QoS升降级策略进行了公平性分析.仿真实验结果表明,在提供一定用户QoS保证下,提出的新策略比传统固定带宽分配策略在带宽资源利用率和系统阻塞上有显著的改善.     

全局主动带宽调整算法

近年来,UDP等非响应流抢占TCP等响应流的现象越来越严重。提出全局主动带宽调整算法（GABA）,通过网络中核心路由器与边缘路由器之间的协作,在核心路由器获取非响应流的信息,在边缘路由器阻止非响应流的大量进入。通过NS2仿真表明,GABA可以有效提高网络利用率和带宽分配的公平性。     

自适应带宽的最大-最小公平性拥塞控制

带宽共享和拥塞控制对于Internet的健壮性和公平性是很重要的研究课题.对交换设备中流量共享拥塞链路的带宽公平分配进行研究,提出一个优化交换设备带宽的设置算法:根据出端口接收速率自适应设置入端口带宽门限,对入端口的带宽进行动态重新分配,提高资源利用率.模拟实验表明,此算法有以下优点:1)高适应性;2)最大最小公平性;3)快速响应网络变化;4)高可靠性;5)稳定性.     

基于最小接入保证带宽的数据中心网络带宽分配机制

针对云计算数据中心（DC）网络中多租户间易相互干扰导致应用性能不可预测,预留带宽资源难以保证高网络利用率,从而导致云网络供应商收益损失等问题,提出了基于最小接入保证带宽的数据中心网络带宽分配（MAGBA）机制。MAGBA机制在发送端通过加权公平队列调度租户虚拟机（VM）流量,在接收端基于检测到的接收速率调节TCP流接收窗口,从而为租户VM提供最小接入保证带宽,同时充分利用闲置带宽资源。通过NS2平台仿真,MAGBA机制相比静态资源预留方式能够灵活分配带宽资源,网络吞吐量提升25%。当某些租户产生大量TCP流时,MAGBA机制中其他租户分得的带宽高于现有基于TCP流的带宽分配机制。仿真结果表明,MAGBA机制能够为租户VM提供最小接入带宽保证,避免租户应用受到其他租户通信模式的干扰。     

基于负载均衡的无线虚拟网络映射算法

针对网络僵化的问题,目前多采用网络虚拟化（NV）方法进行解决,其关键技术是虚拟网络映射（VNE）。为解决无线VNE过程中功率和带宽资源使用不均衡的问题,基于负载均衡原理提出一种联合资源分级的无线VNE算法。首先,采用新的节点资源排序方式,其中将节点功率和平均链路带宽作为排序依据;其次,对资源进行分级,以动态调整虚拟网络请求对功率和带宽资源的需求;最后,改进功率和带宽资源的单位成本,并以最小化成本为目标函数选择资源分配方案。与原有的无线VNE算法WVNE-JBP相比,所提算法的总体接受率提高了11.7个百分点,平均功率利用率提高了4.4个百分点,平均带宽利用率提高了1.6个百分点。实验结果表明,所提算法能有效提高虚拟网络接受率和资源利用率。     

一种基于IEEE 802.16j网络的带宽调度方案*

针对IEEE 802.16j网络,提出了一种上行业务的动态联合带宽资源调度方案。根据该网络系统树状拓扑结构,在基站BS和中继站RS间采用分级分布式资源调度体制,从而既保障了业务的带宽需求,又提升了上行带宽利用率,同时还提出了针对不同类型业务采用不同的调度算法,改善了调度的公平合理性。仿真结果表明,提出的动态联合调度方案相比严格优先级调度更具灵活性,能够在兼顾用户速率公平的条件下有效地保证各种服务的QoS要求,同时也可获得较高的带宽资源利用率。     

嵌入式多通道无线视频传输的码率自适应算法

无线视频传输和视频压缩技术是当前众多物联网（IoT）应用和嵌入式系统的基础和核心。而在多通道传输时无线网络状态的不断变化,会导致视频丢帧和延时抖动问题。虽然自适应算法能够在一定程度上解决在PC或服务器平台下的视频传输问题,但在嵌入式平台和无线网络下仍不能满足实时性和服务质量（QoS）要求。为此,基于DM368芯片设计了一从视频采集、压缩、WiFi传输、控制单元接收到上位机显示的完整平台。同时充分考虑了嵌入式平台的特点,提出一种结合信号质量、网络带宽、缓存状态和拥塞控制的码率自适应算法。该算法利用高斯函数统计网络带宽,使用分段反比例函数调整缓存状态,利用加权移动法对码率进行平滑,并使用极值抑制法进行码率均衡。该算法实现了码率的平滑调整,并被应用于所提平台来实现控制单元对多个WiFi相机的管理、多通道传输和负载均衡。以QoS为评价指标进行实验验证,结果表明：该算法在设计的嵌入式平台上性能良好,平滑性和缓存稳定性都有很大提升,多通道状态下的公平性和带宽利用率也有显著提高。在单相机信号质量动态变化或多相机竞争带宽等多种情况下,相对于MDI（McGinely Dynamic Indicator）算法,该算法的平滑性提升了16%~59%;相对于BBA（Buffer-Based Algorithm）,该算法的缓存抖动降低了15%~72%,时延抖动降低了12%~76%。     

基于VNF组合的服务功能链设计及映射算法

为优化网络功能虚拟化中服务功能链的设计和映射过程,提高物理资源利用率,提出一种基于虚拟网络功能(VNF)组合的服务功能链设计及映射算法A-VNFC.使用整数线性规划(ILP)模型,在小规模物理网络中求出目标函数总带宽消耗(TBC)的最优解,寻找可组合的VNF,并利用VNF决策树检查所有组合策略,通过迭代和优化降低TBC.仿真结果表明,A-VNFC算法可在不同场景下有效降低带宽消耗,其TBC数值接近ILP模型获得的最小带宽消耗值.     

Fairness in broadband ISDNs

In order to achieve satisfactory performance in broadband Integrated Services Digital Networks (ISDNs), some techniques to control flow of information traffic, are necessary. Bandwidth allocation, bandwidth enforcement, and load balancing, are some of the examples of these techniques. Unfortunately, some of these techniques result in unfair distribution of resources among users. Recently, fairness in resource sharing systems has received significant attention among researchers.

In this paper, we discuss, in comparative terms, several resource allocation techniques along with their fairness aspects in broadband ISDNs. We will also propose a threshold-based scheme to minimize the blocking probability and improve fairness.     

在区分服务机制环境下构建VPN

当前基于尽力传送模型的Internet不能提供有效的服务质量,因此IETF提出了两种支持服务质量的体系结构：面向动态虚电路的Intserv和无连接的Diffserv。文章在比较分析两种体系结构的基础上,研究了在Internet上,采用区分服务机制如何实现VPN（virtual private network）功能,特别是对基于代理的带宽管理、支持QoS的VPN、安全机制、计帐机制等方面进行了分析、研究。这样,支持QoS的VPN将能取代昂贵的基于租用专线的私有网络。     

基于层次回声状态网络的电力EPON业务流感知

为了进一步提高电力EPON（Ethernet Passive Optical Network）对智能电网多业务的支持能力,文章提出了一种层次基于回声状态网络的电力EPON业务流感知技术,采用离散回声状态网络算法对电力通信业务流进行识别感知,以实现EPON对业务的高效匹配能力。在此基础上通过OLT与ONU的交互,优化电力EPON的资源调度与分配能力。为了验证所提出的业务流感知机制,以配用电通信EPON作为典型业务,对基于回声状态网络算法的业务感知进行仿真,仿真结果表明该机制能有效降低丢包率和缩短时延,提高了EPON系统对电力通信多业务的支持能力。     

Optimized Resource Allocation for IoT-D2D Communication Using WSN

The need for a strong system to access radio resources demands a change in operating frequency in wireless networks as a part of Radio Resource Management (RRM). In the fifth-generation (5G) wireless networks, the capacity of the system is expected to be enhanced by Device-to-Device (D2D) communication. The cooperation and Resources Allocation (RA) in the development of Internet of Things (IoT) enabled 5G wireless networks are investigated in this paper. Developing radio RA methods for D2D communication while not affecting any Mobile Users’ (MU) communication is the main challenge of this research. Distinct performance goals such as practising equality in the rates of user data, increasing Network Throughput (NT), and reducing End-to-End Delay (EED) are achieved by RA. The study undertaken on optimising performance for various wireless networks is focused on in this research work. Proposing a polynomial-time Proportional Fair Resource Allocation Method (PFRAM), which considers the MU’s rate requirements, is the prime objective of this paper. Any Resource Allocation Method (RAM) can be used by the proposed method for MU, and the time and differing location channel conditions are the factors to be adapted with. Allotting more than one resource block is allowed by our PFRAM to a D2D pair. The automatic maintenance of battery-less IoT wireless devices’ energy level is done potentially using an Extensible Energy Management System (EEMS). Finally, the device’s Node Transmission Power (NTP) can be managed using an Energy-Saving Algorithm (ESA) designed in this work for Node Uplink Data Transmission (NUDT). The trade-off between the Packet Loss Rate (PLR) and NTP is balanced by the algorithm. The cost of NUDT’s average Energy Consumption (EC) is reduced by locating the optical NTP. In order to free much bandwidth for wireless information, NUDT conserves the harvested energy for minimising Radio Frequency (RF) Energy Transmission (ET). MATLAB simulations are used to assess the proposed EEMS. The IoT device’s NTP is managed using ESA designed for NUDT. The significant minimisation of channel hopping EED and the selection of the premium quality communication channel by the proposed framework are indications of the simulation results. 67.19% is the bandwidth to transmit DPs with the Bandwidth Allocation Algorithm (BAA), which is greater than the cases in its absence.     

动态带宽分配分级QoS链路接入控制算法

针对传统的基于带宽请求链路接入控制算法（Link Bandwidth Require Control Algorithm,LBRCA）的接入成功率和系统带宽利用率不高的问题,设计了一种多链路接入共享带宽分配模型,分析了链路带宽分配和QoS等级的特点,提出一种动态带宽分配分级QoS链路接入控制算法DBAMQ（Dynamic Bandwidth Allocation and Multi-level QoS）,该算法在保证某QoS等级的基础上允许动态地对系统的带宽进行重分配。实验结果表明,该算法在接入成功率、系统总带宽利用率和系统效能等都比传统链路接入控制算法好,适合于大规模宽带接入链路控制的应用。     

Resource-aware and quality-fair video-streaming using multiple adaptive TCP connections

In this paper, we present a resource-aware and quality-fair video content sharing system. When a video sharing server has insufficient uplink bandwidth and needs to serve multiple video content sharing services via streaming or downloading to other client peers using TCP transport, each service shares the limited uplink bandwidth equitably, due to the fair sharing characteristics inherent in TCP. However this bandwidth fair sharing cannot always guarantee quality fairness among the services, due to the specific requirements for video-streaming services, such as the playout rate and the size of the playout buffer. In our system, the server uses multiple TCP connections adaptively, depending on the anticipated status of each client playout buffer, to guarantee the bandwidth of each video-streaming session. By guaranteeing the quality of each video-streaming session, without the quality loss of other service sessions, the proposed system can successfully achieve service quality fairness. Simulation results show that our proposed algorithm can dramatically enhance the quality of each streaming session and thus provide service quality fairness among simultaneous multiple heterogeneous video-streaming services and content download services.