Active intra-ONU scheduling with proportional guaranteed bandwidth in long-reach EPONs

The unused slot remainder (USR) problem in Ethernet Passive Optical Networks and long-reach Passive Optical Networks (LR-PONs) results in both a lower bandwidth utilization and a greater packet delay. In a previous study by the current group, an Active intra-ONU Scheduling with predictive queue report scheme was proposed for resolving the USR problem by predicting the granted bandwidth in advance based on the arrival traffic estimates of the optical network units (ONUs). However, it was found that the higher bandwidth prediction error in the proposed scheme prevents the network performance from being improved. Accordingly, the present study proposes a non-predictive-based ONU scheduling method designated as Active intra-ONU Scheduling with proportional guaranteed bandwidth (ASPGB) to improve the performance of LR-PONs. In the proposed method, the maximum guaranteed bandwidth of each ONU is adapted dynamically in accordance with the ratio of the ONU traffic load to the overall system load. Importantly, the proposed dynamic bandwidth allocation approach reduces the dependence of the network performance on the granted bandwidth prediction since the maximum guaranteed bandwidth determined by the Optical Line Terminal more closely approaches the actual bandwidth demand of each ONU. To solve the idle time problem arising in the event of an excess bandwidth reallocation, ASPGB is integrated with an improved early allocation (IEA) algorithm (a kind of Just-In-Time scheduling). The simulation results show that the IEA-ASPGB scheme outperforms previously published methods in terms of bandwidth utilization and average packet delay under both balanced and unbalanced traffic load conditions.     

Inter‐ONU Bandwidth Scheduling by Using Threshold Reporting and Adaptive Polling for QoS in EPONs

I dynamic bandwidth allocation (DBA) scheme, an inter–optical network unit (ONU) bandwidth scheduling, is presented to provide quality of service (QoS) to different classes of packets in Ethernet passive optical networks (EPONs). This scheme, referred to as TADBA, is based on efficient threshold reporting from, and adaptive polling order rearranging of, ONUs. It has been shown that the network resources are efficiently allocated among the three traffic classes by guaranteeing the requested QoS, adaptively rearranging the polling orders, and avoiding nearly all fragmentation losses. Simulation results using an OPNET network simulator show that TADBA performs well in comparison to the available allocation scheme for the given parameters, such as packet delay and channel utilization.     

Soft QoS provisioning using the token bank fair queuing scheduling algorithm

Future-generation wireless packet networks will support multimedia applications with diverse QoS requirements. Much of the research on scheduling algorithms has been focused on hard QoS provisioning of integrated services. Although these algorithms give hard delay bounds, their stringent requirements sacrifice the potential statistical multiplexing performance and flexibility of the packet-switched network. Furthermore, the complexities of the algorithms often make them impractical for wireless networks. There is a need to develop a packet scheduling scheme for wireless packet-switched networks that provides soft QoS guarantees for heterogeneous traffic, and is also simple to implement and manage. This article proposes token bank fair queuing (TBFQ), a soft scheduling algorithm that possesses these qualities. This algorithm is work-conserving and has a complexity of O(1). We focus on packet scheduling on a reservation-based TDMA/TDD wireless channel to service integrated real-time traffic. The TBFQ scheduling mechanism integrates the policing and servicing functions, and keeps track of the usage of each connection. We address the impact of TBFQ on mean packet delay, violation probability, and bandwidth utilization. We also demonstrate that due to its soft provisioning capabilities, the TBFQ performs rather well even when traffic conditions deviate from the established contracts.     

基于VBR视频流量预测技术的DVB-H复用器调度算法

DVB-H采用的时间分片技术对现有的复用器算法提出了挑战.本文在VBR视频流量预测技术的基础上提出了基于VBR视频流量预测技术的DVB-H网络复用器调度算法.本算法根据VBR视频码率的预测值,预先分配下一调度周期的带宽,满足了时间分片技术对复用器调度算法的要求.与CBR调度算法相比,本算法具有较小的时延和较高的带宽利用率.     

Toward Quality of Service Protection in Ethernet Passive Optical Networks: Challenges and Solutions

This article surveys various solutions proposed to date to support quality of service in EPONs. Namely, we overview the inter-and intra-ONU scheduling solutions and argue, and later show, that although these solutions can help in supporting QoS, they fall short of protecting the requirements of the admitted traffic, especially as the network becomes saturated. Hence, we present an admission control framework that is capable of supporting and protecting the QoS of real-time traffic while guaranteeing a minimum bandwidth for best effort traffic, and present an appropriate dynamic bandwidth allocation algorithm. Finally, we present numerical results to show the effectiveness of the proposed solution and compare the performance with that of intra-ONU scheduling solutions.     

Bandwidth negotiation scheduling with dynamic zone adjustment for 802.16j mobile multihop relay networks

This paper presents a bandwidth negotiation scheduling (BNS) for IEEE 802.16j mobile multihop relay (MMR) networks. In MMR networks, two bandwidth scheduling zones, Access and Relay zones, are specified for direct access and forwarding sessions, respectively. One of the novelties in the proposed BNS is that bandwidth negotiation is conducted between the Access and Relay zones. In other words, a higher‐priority traffic class in a high‐utilization zone may receive extra bandwidth from low‐utilization zone when its delay constraint or bandwidth requirement cannot be satisfied. In addition, when the assigned bandwidth to non‐real‐time polling service (nrtPS) has exceeded its minimum requirement, the proposed BNS can avoid possible starvations for best effort (BE) traffic by receiving extra bandwidth from nrtPS. Through multidimensional Markov formulation, we evaluate the performance of the BNS and compare it with a fixed‐boundary scheme. The analytical results have shown that the proposed BNS can increase delay‐constraint satisfactions for real‐time polling service and decrease the packet loss rate for BE. Furthermore, the overall system throughput can be increased significantly because of an improvement on bandwidth utilization. Copyright © 2012 John Wiley & Sons, Ltd.     

Fair Delay Optimization-based Resource Allocation Algorithm for Video Traffic over Wireless Multimedia System

The major issue related to the realization of wireless multimedia system is the design of suitable medium access control (MAC) protocol. The design challenge is to maximize the utilization of the limited wireless resources while guaranteeing the various quality of service requirements for all traffic classes especially for the stringent real-time constraint of real time variable bit rate (rt-VBR) video service. In this paper a novel resource allocation algorithm for video traffic is proposed. The proposed allocation algorithm aims to provide fair delay for video packets by minimizing the delay difference among transmitted video packets. At the same time it adaptively controls the allocated resources (bandwidth) for video traffic around the corresponding average bit rate, and has the ability of controlling the quality of service (QoS) offered for video traffic in terms of packet loss probability and average delay. A minimized control overhead of only two bits is needed to increase the utilization efficiency. Simulation results show that the proposed algorithm achieves very high utilization and provides nearly fair delay among video packets. Its efficiency is also investigated under traffic integration condition with voice and data traffic to show that the QoS offered to video traffic does not change in the presence of the highest priority voice traffic while data traffic increases the channel utilization to 98% by using the remaining bandwidth after voice and video traffic while a good QoS is offered to voice and data traffic.

EPON中保证QoS的动态带宽分配算法

作为一种新技术，EPON系统采取在下行信道使用广播方式而在上行信道使用时分多址(TDMA)方式，为用户提供共享传输介质的接入方式，因此就需要一种接入控制机制来为用户分配带宽。为了使EPON系统更好地支持QoS并且进一步提高带宽利用率，提出了一种新的固定周期轮询动态带宽分配算法，针对不同时延特性业务采用不同的授权分配算法。算法包括两部分：OLT时ONU的调度以及ONU内部不同优先级的队列之间的调度。最后讨论了包时延、系统吞吐量等仿真结果和性能分析。     

Opportunistic delay‐margin‐based resource allocation for next‐generation wireless networks

This paper studies and develops efficient traffic management techniques for downlink transmission at the base station (BS) of multi‐service IP‐based networks by combining quality‐of‐service (QoS) provision and opportunistic wireless resource allocation. A delay‐margin‐based scheduling (DMS) for downlink traffic flows based on the delays that each packet has experienced up to the BS is proposed. The instantaneous delay margin, represented by the difference between the required and instantaneous delays, quantifies how urgent the packet is, and thus it can determine the queuing priority that should be given to the packet. The proposed DMS is further integrated with the opportunistic scheduling (OPS) to develop various queueing architectures to increase the wireless channel bandwidth efficiency. Different proposed integration approaches are investigated and compared in terms of delay outage probability and wireless channel bandwidth efficiency by simulation. Copyright © 2010 John Wiley & Sons, Ltd.     

Efficient Traffic Scheduling for Real Time VBR MPEG Video Transmission Over DOCSIS-Based HFC Networks

Data-over-cable service interface specifications (DOCSIS), the de facto standard in the cable industry, defines a scheduling service called real-time polling service (rtPS) to provision quality of service (QoS) transmission of real-time variable bit rate (VBR) videos. However, the rtPS service intrinsically has high latency, which makes it not applicable to real-time traffic transport. In this paper, we present a novel traffic scheduling algorithm for hybrid fiber coax (HFC) networks based on DOCSIS that aims to provide QoS for real-time VBR video transmissions. The novel characteristics of this algorithm, as compared to those described in published literatures, include 1) it predicts the bandwidth requirements for future traffic using a novel traffic predictor designed to provide simple yet accurate online prediction; and 2) it takes the attributes of physical (PHY) layer, media access control (MAC) layer and application layer into consideration. In addition, the proposed traffic scheduling algorithm is completely compatible with the DOCSIS specification and does not require any protocol changes. We analyze the performance of the proposed traffic predictor and traffic scheduling algorithm using real-life MPEG video traces. Simulation results indicate that 1) the proposed traffic predictor significantly outperforms previously published techniques with respect to the prediction error and 2) Compared with several existing scheduling algorithms, the proposed traffic scheduling algorithm surpasses other mechanisms in terms of channel utilization, buffer usage, packet delay, and packet loss rate.     

A packet scheduling scheme for 4G wireless access systems aiming to maximize revenue for the telecom carriers

Efficient utilization of network resources is a key goal for emerging BWAS. This is a complex goal to achieve due to the heterogeneous service nature and diverse QoS requirements of various applications that BWAS support. Packet scheduling is an important activity that affects BWAS QoS outcomes. This paper proposes a new packet scheduling mechanism that improves QoS in mobile wireless networks which exploit IP as a transport technology for data transfer between BWAS base stations and mobile users at the radio transmission layer. In order to improve BWAS QoS the new packet algorithm makes changes at both the IP and the radio layers. The new algorithm exploits handoff priority scheduling principles and takes into account buffer occupancy and channel conditions. The packet scheduling mechanism also incorporates the concept of fairness. The algorithm offers an opportunity to maximize the carriers’ revenue at various traffic situations. Simulation results were compared to well-known algorithms which demonstrated the new packet scheduling algorithm is able to provide a low handoff packet drop rate, low packet forwarding rate, low packet delay, ensure fairness amongst the users of different services and generates higher revenue. Furthermore this research proposes a new and novel measure named “Satisfaction Factor” to measure the efficacy of various scheduling schemes and finally proposes four performance metrics for NodeB’s of in Next Generation Wireless Networks.     

A Modified Dynamic Weighted Round Robin Cell Scheduling Algorithm

In this paper, we propose the modified dynamic weighted round robin (MDWRR) cell scheduling algorithm, which guarantees the delay property of real‐time traffic and also efficiently transmits non‐real‐time traffic. The proposed scheduling algorithm is a variation of the dynamic weighted round robin (DWRR) algorithm and guarantees the delay property of real‐time traffic by adding a cell transmission procedure based on delay priority. It also uses a threshold to prevent the cell loss of non‐real‐time traffic that is due to the cell transmission procedure based on delay priority. Though the MDWRR scheduling algorithm may be more complex than the conventional DWRR scheme, considering delay priority minimizes cell delay and decreases the required size of the temporary buffer. The results of our performance study show that the proposed scheduling algorithm has better performance than the conventional DWRR scheme because of the delay guarantee of real‐time traffic.     

车联网中交通安全消息动态优先调度机制

车联网中两类交通安全消息共享有限控制信道带宽,在消息突发状态下无法保证事件触发消息的传播性能,导致预警失效.基于差异化的消息传播性能需求提出了一种动态优先级区分的调度机制,按事件优先级分别进行队列管理,赋予事件触发消息优先权,通过设置优先级调度阈值实现对事件触发消息的动态调度.当优先队列长度高于阈值时,其抢占调度时隙.当队列长度低于阈值一半,退出抢占过程,恢复非抢占优先调度方法.仿真显示,所提调度机制能够减小事件触发消息的端到端时延约1.3 ms,提高周期性消息的公平性约0.22.     

Network queue scheduling algorithm based on self-similar traffic level grading prediction

Self-similarity characteristic of network traffic will lead to the continuous burstness of data in the network.In order to effectively reduce the queue delay and packet loss rate caused by network traffic burst,improve the transmission capacity of different priority services,and guarantee the service quality requirements,a queue scheduling algorithm P-DWRR based on the self-similarity of network traffic was proposed.A dynamic weight allocation method and a service quantum update method based on the self-similar traffic level grading prediction results were designed,and the service order of the queue according was determined to the service priority and queue waiting time,so as to reduce the queuing delay and packet loss rate.The simulation results show that the P-DWRR algorithm can reduce the queueing delay,delay jitter and packet loss rate on the basis of satisfying the different service priority requirements of the network,and its performance is better than that of DWRR and VDWRR.     

iRGRR/PM：一种新的高速crossbar分组调度策略

iRGRR(iterative Request-Grant-based Round-Robin)算法是一种输入排队crossbar调度算法,具有硬件易实现、可扩展性强、性能优良等优点.在此基础上,该文提出一种新的高速crossbar分组调度策略iRGRR/PM(iRGRR with Packet Mode),可以更好地支持IP分组的调度,能够被应用于高速、大容量的路由器中.与iRGRR算法相比,iRGRR/PM简化了分组输出重组模块的设计,并且提高了crossbar的带宽资源利用率.文中简单分析了两种算法间的分组时延关系,并进行了详尽的仿真研究.结果表明:在相同条件下,iRGRR/PM算法具有更高的吞吐量,尤其在非均匀业务流下能获得接近100%的吞吐量;调度长分组时,iRGRR/PM算法具有更好的时延性能.     

A joint-ONU interval-based dynamic scheduling algorithm for Ethernet passive optical networks

This paper proposes a new dynamic bandwidth allocation system for Ethernet Passive Optical Networks (EPONs), subject to requirements of fairness, efficiency, and cost. An Optical Line Terminal (OLT)-centric bandwidth allocation model is proposed which employs a credit pooling technique combined with a weighted-share policy to partition the upstream bandwidth among different classes of service, and to prevent Optical Network Units (ONUs) from monopolizing the bandwidth. The OLT-centric model allows global optimization of network resources, a characteristic which is not found in many earlier proposals. Supported by the new bandwidth allocation, the paper proposes a joint-ONU interval-based packet scheduling algorithm, referred to herein as COPS (Class-of-service Oriented Packet Scheduling), that meets the requirements set out above. We compare COPS with another well-known scheduling algorithm which employed a standard priority-based bandwidth sharing. We show that COPS is superior in terms of network utilization and maximum packet delay, with the consequence of an increase in average packet delay for the premium traffic. This drawback is overcome by combining COPS with a rate-based optimization scheme.     

一种基于时延补偿的星上分组调度算法

EDF策略具有有线调度算法中最大调度域和时延保障特性,根据分组时延要求确定服务优先级,是一种动态权重调度策略,通过将IQ-VOQ结构EDF策略引入无线调度并通过加入信道补偿机制和门限丢弃策略,得到一种新的算法IQCEDF,它避开公平排队固有的时延一带宽耦合问题,获得了比EDF更加出色的时延特性,更适于为卫星通信系统分组业务提供服务质量保证。     

流量管理中队列调度算法研究

介绍了包交换芯片流量管理中队列调度的算法,分析DWRR(Deficit Weighted Round-Robin)算法的优缺点,并提出了一种基于DWRR改进的调度算法.该算法能够根据网络中实时的数据包帧长,来调节每次轮询中向各个队列添加的信用度,能够减少各个队列的时延,同时又增强带宽分配的相对公平性,改善了DWRR算法不能很好满足业务的时延特性.使用NS-2仿真器来对改进的算法进行网络仿真,最终的仿真结果表明改进后的DWRR算法能够有效地降低时延,可以在一定程度上提高QoS.     

Cross-Layer MAC Protocol and Holistic Opportunistic Scheduling with Adaptive Power Control for QoS in WiMAX

Providing quality of service (QoS) to different service classes with integrated real-time and non-real-time traffic is an important issue in broadband wireless access networks. Opportunistic MAC (OMAC) is a novel view of communication over spatiotemporally varying wireless link whereby the multi-user diversity is exploited rather than combated to maximize bandwidth efficiency or system throughput. It combines cross-layer design features and opportunistic scheduling scheme to achieve high utilization while providing QoS support to various applications. Channel characteristics, traffic characteristics and queue characteristics are the essential factors in the design of opportunistic scheduling algorithms. In this paper, we propose a cross-layer MAC scheduling framework in WiMAX point-to-multipoint (PMP) systems and a corresponding opportunistic scheduling algorithm with an adaptive power control scheme to provide QoS support to the heterogeneous traffic. Extensive simulation experiments have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can improve the performance of the WiMAX PMP systems in terms of packet loss rate, packet delay and system throughput.     

Optimized Packet Scheduling Management: Maximizing Bandwidth Utilization for Next-Generation Mobile Multimedia Communications

Base stations in next-generation broadband mobile networks (NGBMNs) must efficiently schedule different kinds of multimedia packets providing different quality of service (QoS) classes. During the past 10?years, many researchers have experimented with various packet scheduling schemes. In this paper we will propose a batch-arrival queuing model for evaluating NGBMN multimedia packet scheduling systems, and for obtaining three performance measures: packet loss rate (PLR), queuing delay (QD), and bandwidth utilization (BU). The three measures can be used to solve utilization optimization problems with QoS constraints. Specifically, a combination of a traffic statistic plus maximum PLR and QD constraints can be used to maximize BU for a multimedia packet scheduling management architecture. According to results from mathematical tests of the proposed model, it offers an efficient approach to managing scheduling buffers. The model and optimized parameters can be applied to flexible bandwidth deployment and classified buffer size control, thus enhancing profitability.