SNMP-based acquisition system for DiffServ parameters

Modern communication networks cannot get along without quality of service (QoS) assurance. QoS-support mechanisms offer preferential treatment for specific traffic classes that is required especially by real-time network applications. Unfortunately current QoS technologies have certain disadvantages and limitations and therefore they are not always able to guarantee the required QoS level. This paper introduces a quality of service support system that improves the most often used quality of service support technology called Differentiated Services (DiffServ). The system proposed utilizes the Simple Network Management Protocol (SNMP) for the acquisition of configuration information from the edge router of the DiffServ domain. This information is subsequently used to control the allocation of network resources within the QoS assurance process. In order to evaluate this system we used the OPNET Modeler simulation environment where we built a simulation scenario able to interact with real network components. For this purpose we implemented the SNMP protocol into the OPNET Modeler and used it for acquisition of management information, stored in the Management Information Base (MIB) of the network node. The paper describes in details the improved QoS-support mechanism and the simulation model able to cosimulate the behavior of both real and virtual network elements.     

Programmable agents for flexible QoS management in IP networks

Network programmability seems to be a promising solution to network management and quality of service (QoS) control. Software mobile-agents technology is boosting the evolution toward application-level control of network functionalities. Code may be deployed in the network dynamically and on demand for the benefit of applications or application classes. Agents support a dynamic distribution of control and management functions across networks, thus increasing flexibility and efficiency. We propose to use mobile-agent technology to overcome some of the problems inherent in current Internet technology. We focus our attention to QoS monitoring, being locally significant in network subdomains, and realize a QoS management strategy in response to variations of user, customer of application requirements, and of the network state. We describe our experience and the results obtained from our testbed, where software agents are instantiated, executed, migrated, and suspended in order to implement flexible QoS management in IP networks     

QoS provisioning in GEO satellite with onboard processing using predictor algorithms

Recently, IP satellite networks have attracted considerable interest as a technology to deliver high-bandwidth IP-based multimedia services to nationwide areas. In particular, IP satellite networks seem to be one of the most promising technologies for connecting users in rural areas, where a wired high-speed network (e.g., xDSL) is not foreseen to be used. However, one of the main problems arising here is to guarantee specific quality of service constraints in order to have good performance for each traffic class. Among various QoS approaches used in the Internet, recently the DiffServ technique has become the most promising solution, mainly for its scalability with respect to the IntServ approach. Moreover, in satellite communication systems, DiffServ computational capabilities are placed at the edge points, reducing the implementation complexity of the satellite onboard equipment. This article deals with the problem of QoS provisioning for packet traffic by considering some resource allocation schemes, including bandwidth allocation techniques and priority-driven onboard switching algorithms. As to the first aim, the proposed technique takes advantage of proper statistical traffic modeling to predict future bandwidth requests. This approach takes into consideration DiffServ-based traffic management to guarantee QoS priority among different users. Moreover, the satellite onboard switching problem has been addressed by considering a suitable implementation of the DiffServ policy based on a cellular neural network.     

On the Feasibility of Dynamic Congestion-Based Pricing in Differentiated Services Networks

Differentiated services can ensure that traffic on some codepoints receives higher quality of service (QoS) than traffic on other codepoints, but without additional mechanisms it cannot target any particular QoS. Congestion-based pricing has been suggested as a method to target QoS in other network architectures. Here, we investigate whether congestion-based pricing can be used to control aggregate traffic into each codepoint by motivating users to choose the codepoints appropriate for each application. We first ask what information needs to be exchanged; we assert that both price and QoS information must be available for users to make decisions. We then ask how effective congestion-based pricing in diffServ can be; we find that it is feasible only for networks with sufficiently high bandwidth to guarantee that QoS can be quickly measured.      

Multi‐step solution for QoS management in wireless mesh networks

Wireless mesh networks (WMNs) as community‐ and city‐wide type networks are required to extend their capability to offer real‐time multimedia services. While technologies exist to support quality of service (QoS) at node level, we propose here a network‐wide multi‐step solution to manage and offer QoS across a WMN. From a provider perspective, the provisioning and fulfillment of QoS‐based services fall under the realms of service management, network and traffic engineering functions. We describe the relevant functions required to design, implement and operate a WMN for providing a qualitative QoS to end‐users. Our proposed solution considers network planning aspects, including node placement, node clustering and frequency assignments, route discovery between ingress–egress points and appropriate QoS provisioning across the network. Route‐level QoS provisioning is defined as the process of allocating resources to the nodes along the identified routes to meet a priori known aggregated traffic demands in order to satisfy the QoS requirements for different types of application. Simulation and experimental tests are conducted to validate the correct behavior of processes/algorithms and to access the solution in achieving QoS for aggregate user traffic. Copyright © 2012 John Wiley & Sons, Ltd.     

MPLS技术在全球范围内的争议

MPLS技术兼具了IP技术的灵活性和ATM技术交换速度快、有QoS保证、流量控制等诸多优点,可以解决网络中存在的拥塞、QoS、VPN支持和组播等方面的一系列问题,是一种新兴的IP骨干网技术。但经过几年的实践,人们对它的能力提出怀疑出现了争论。从MPLS这几年的发展历程看,MPLS是目前最有希望的下一代骨干网技术之一,但它并不象原来设想的那样,可以解决网络中存在的所有问题。     

Joint QoS-control and handover optimization in backhaul aware SDN-based LTE networks

Future cellular networks will be dense and require key traffic management technologies for fine-grained network control. The problem gets more complicated in the presence of different network segments with bottleneck links limiting the desired quality of service (QoS) delivery to the last mile user. In this work, we first design a framework for software-defined cellular networks and then propose new mechanisms for management of QoS and non-QoS users traffic considering both access and backhaul networks, jointly. The overall SDN-LTE system and related approaches are developed and tested using network simulator in different network environments. Especially, when the users are non-uniformly distributed, the results shows that compared to other approaches, the proposed load distribution algorithm enables at least 6% and 23% increase in the average QoS user downlink throughput and the aggregate throughput of 40% users with lowest throughput (edge users), respectively. Also, the proposed system efficiently achieves desired QoS and handles the network congestion without incurring significant overhead.

     

Application-Oriented Flow Control: Fundamentals, Algorithms and Fairness

This paper is concerned with flow control and resource allocation problems in computer networks in which real-time applications may have hard quality of service (QoS) requirements. Recent optimal flow control approaches are unable to deal with these problems since QoS utility functions generally do not satisfy the strict concavity condition in real-time applications. For elastic traffic, we show that bandwidth allocations using the existing optimal flow control strategy can be quite unfair. If we consider different QoS requirements among network users, it may be undesirable to allocate bandwidth simply according to the traditional max-min fairness or proportional fairness. Instead, a network should have the ability to allocate bandwidth resources to various users, addressing their real utility requirements. For these reasons, this paper proposes a new distributed flow control algorithm for multiservice networks, where the application's utility is only assumed to be continuously increasing over the available bandwidth. In this, we show that the algorithm converges, and that at convergence, the utility achieved by each application is well balanced in a proportionally (or max-min) fair manner     

一种提供电信级QoS的IP网络体系架构

本文将IP业务网络系统按照功能分为三个平面:承载面、信令面和业务面.承载面承载媒体与信令流,信令面完成各种控制功能,应用面是媒体资源服务器.承载面使用MPLS技术,进行带宽预规划,满足需要QoS的业务,并在接入层完成对用户接入及流量的各种控制功能.互联网业务则走普通的IP路由.从而实现基于IP网络,既能提供保证电信级QoS的业务,同时支持普通互联网业务的网络体系结构,具有良好的网络与业务扩展性.     

IP QoS技术的现状与发展趋势

文章介绍了IP服务质量的研究背景和意义，然后从用户业务流量控制和网络业务管理两个方面剖析了IP服务质量方面的主要技术，讨论了当前的服务质量研究现状和存在的问题，最后指出了该项技术的发展趋势。     

Separation principle of dynamic transmission and enqueueingpriorities for real- and nonreal-time traffic in ATM multiplexers

In order to efficiently utilize network resources while still providing satisfactory QoS to both real-time and nonreal-time applications, prioritizing these two types of traffic according to their service requirement becomes necessary. Several slot-oriented transmission priority schemes applicable to the output queue of ATM switches have been proposed. We studied the slot-oriented queueing disciplines that further involve the buffer management of the output queue of ATM switches. A fundamental principle called the separation principle is presented, which asserts that (1) the QoS (measured by the time-cumulative cell loss for each traffic class) region of the efficient disciplines (provide the best QoS tradeoff between the two types of traffic) can be divided into two mutually exclusive ones by the QoS of a special efficient discipline called R*; and (2) the efficient disciplines may involve either dynamic transmission priority or dynamic enqueueing priority but not both depending on which of the two mutually exclusive QoS regions is desired. The QoS region of less time-cumulative nonreal-time cell loss than R* is shown to be approximately linear in the space of time-cumulative cell loss vector when the real-time traffic is well regulated. The suboptimal but simple disciplines which are functions of only a small set of system parameters are also investigated to achieve less time-cumulative nonreal-time cell loss than R*     

3G动态预留呼叫接纳控制算法研究

第三代移动通信技术支持不同服务质量(QoS)的多媒体业务,而呼叫接纳控制(CAC)技术是移动通信中的关键技术之一.本文提出一种动态预留呼叫接纳控制算法,该算法根据小区中各业务的话务量预测各业务所需信道教,从而为切换业务和新业务预留一定的信道.通过比较动态预留算法与新呼叫受限算法和中断优先级算法的性能,得出动态预留算法在降低语音和数据业务的呼叫阻塞率、中断率方面有明显的改善,是一种比较理想的呼叫接纳控制算法.     

IP网络QoS问题和对策

服务质量(QoS)技术是IP网络技术能否成为未来统一承载网络技术的关键。根据拥塞持续时间,网络QoS风险可以分为微秒级、毫秒级、秒级、分钟级,和更长时间级别等5个等级。调度机制、缓存和队列、呼叫接纳控制、流量工程等技术均是解决一类QoS风险的有效手段。IP网络运营商需要在分析网络中主要风险的基础上制定整体QoS解决方案,在呼损、时延、抖动、丢包4项指标中取得均衡。     

QoS Provisioning in Wireless IP Networks

This paper deals with quality of service (QoS) provision in wireless IP networks. QoS provision is particularly challenging in wireless networks, where network resources are generally limited, variable over time and shared. In the design of possible measures to assure QoS one should consider that standardization is well established for the network layer Internet Protocol and for many underlying technologies of frequent use (e.g. IEEE 802.11, BLUETOOTH or HIPERLAN II). Therefore, as far as research on QoS is concerned, there is little room in both the IP and the link-layers for improved IP over wireless interfaces. In this paper we illustrate a solution in which an intermediate Wireless Adaptation Layer (WAL) is transparently interposed between the IP layer and specific link-layer technologies as a solution to provide QoS. The WAL addresses two main issues: (i) compensation for channel impairments in different platforms in order to enhance wireless channel reliability and (ii) implementation of traffic control and packet scheduling mechanisms to satisfy bandwidth and delay requirements, as well as to enforce a general principle of fairness among the IP associations contending for network resources and achieve optimal exploitation of transmission capacity. The WAL consists of a set of modules, each one in charge of a specific task, which can be enabled or disabled depending on the specific network environment. The novelty of the WAL approach is its capability of adapting itself to different wireless interfaces selecting performance enhancing modules for specific networks. This requires to modify the standard TCP/IP protocol stack by introducing an intermediate layer between the IP layer and the Data Link layer, with performance enhancement purposes. This paper focuses on two modules in particular, namely a traffic control module, which is in charge of performing congestion control and channel state dependent scheduling (CSD) packet scheduling, and a forward error correction (FEC) module, which compensates for channel impairments. This paper presents the proposed architecture provided with these modules and reports some measurements and simulations highlighting benefits resulting from the use of such modules.     

Broadband satellite networks-the global IT bridge

Next-generation broadband satellite networks are being developed to carry bursty Internet and multimedia traffic in addition to the traditional circuit-switched traffic (mainly voice) on a global basis. These satellites provide direct network access for personal applications as well as interconnectivity to the terrestrial remote network segments. The main requirement in success of these networks is that they should be able to transmit high data rate traffic with prescribed quality of service (QoS). Thus, the broadband satellite network has no choice other than the rise of ATM technology and to be optimized for Internet-based traffic. ATM is the promising technology for supporting high-speed data transfer potentially suitable for all varieties of private and public telecommunications networks. IP, on the other hand is the fast-growing Internet layer protocol that is applicable over any data link layer Internet-based applications are the emerging source of traffic in the future wireless networks and broadband satellite networks should consider Internet as the primary service. In this paper, we discuss the traditional ATM and wireless ATM networks and explain the characteristics of the wireless IP networks. The paper then uses those concepts in defining the criteria for the broadband satellite networks such as the QoS and traffic management. Application of the broadband satellite networks is also proposed     

An Improved Pillar K-Means Based Protocol for Privacy-Preserving Location Monitoring in Wireless Sensor Network

A number of tiny sensor nodes are strategically placed in and around the human body to obtain physiological information. The sensor nodes are connected to a coordinator or a data collector to form a wireless body area network (WBAN). WBAN consists of variety of medical and non-medical applications with aggregate data rate requirement ranging from few bytes per second to 10 Mbps. These applications are having relatively different energy saving, reliability and quality of service (QoS) requirements. For example, emergency medical data are highly erratic but should be transferred with high reliability and minimum delay, whereas electrocardiogram and electroencephalogram applications are constant bit rate traffic which need to be transferred with moderate reliability. Additionally, non-medical applications include variable bit rate traffic and their jitter and delay requirements must also be met. On the above, a sensor node should spend minimum energy and conserve power to increase its life time in the network. The existing media access control (MAC) protocols present in various short and medium range wireless technologies such as 802.11 and 802.15.4 have been designed for specific purposes, and therefore, do not fulfill the diverse performance requirements across all WBAN applications. In this paper, we propose a poll-based MAC protocol, PMAC for WBAN, which can meet such diversified functional requirements of various WBAN applications. In particular, we introduce few concepts in polling based channel access mechanism to make an energy efficient and QoS aware MAC protocol. The design has been validated by obtaining the performance of proposed PMAC protocol through simulation.     

一种新的对称CDMA系统中非对称业务下的呼叫允许控制策略

未来无线多媒体网络将以分组技术为基础,支持多种业务的传输,业务的QoS保证将受到一定的挑战.各运营商也将针对自己所服务的对象特点,定义各类业务的QoS等级,来提供具有不同QoS要求的业务.因此,呼叫允许控制(Call Admission Control,CAC)策略将要以分组业务为主要对象,即既要在充分利用系统资源的基础上保证各业务的QoS要求,又要适应各运营商之间的不同需求.因此本文提出一种新的对称CDMA系统中非对称业务下基于动态QoS保证的CAC策略.各运营商可根据自己的要求定义各业务的QoS等级.由于业务的不同特性,使得网络中上行链路和下行链路的业务呈现不对称性,为避免资源的浪费,将根据网络中的资源占有情况动态的地分配上行和下行链路中的资源.仿真结果表明,该策略可以自适应地保证各业务的QoS要求,提高了业务间的公平性和系统资源的利用率.     

Quality of Service Management in GPRS-Based Radio Access Networks

In this article, the performance and capacity gain achievable with quality of service (QoS) management in packet switched radio networks based on the General Packet Radio Service (GPRS) are examined. Both the functions defined in the GPRS specification for QoS support and implementation-specific strategies for subscriber- and application-based Connection Admission Control (CAC) and scheduling are introduced. The feasibility of QoS provisioning in mobile core networks with use of DiffServ compared to present IP technology realizing a pure Best-effort service is examined in addition. To achieve this, simulation results of GPRS performance and system measures for different load situations are produced with the simulation tool GPRSim that models the realistic traffic behavior of a GPRS network.     

A bandwidth allocation algorithm with channel quality and QoS aware for IEEE 802.16 base stations

Subscriber stations located in different places encounter various interferences in an IEEE 802.16 network, resulting in that their communication channels experience varying channel conditions. Thus, an excellent bandwidth allocation algorithm should not only satisfy various QoS required by heterogeneous traffic, but also consider the channel quality to maximize bandwidth utilization. In this paper, a bandwidth allocation algorithm with channel quality awareness and QoS guarantee, called CQQ, is proposed. CQQ not only satisfies each connection's QoS requirement, but also dynamically adjusts the downlink/uplink bandwidth to match current downlink/uplink traffic ratio. CQQ allocates more bandwidth to the connections having better channel quality by applying weighted fair queuing strategy to raise the bandwidth usage. CQQ provides lower delay violation ratio and higher goodput than the previous algorithms, as observed from the simulation results. Copyright © 2012 John Wiley & Sons, Ltd.     

Hub‐polling‐based IEEE 802.11 PCF with integrated QoS differentiation

IEEE 802.11 is one of the most influential wireless LAN (WLAN) standards. Point coordination function (PCF) is its medium access control (MAC) protocol with real‐time traffic (rt‐traffic) quality‐of‐service (QoS) guarantees. In PCF, it is very likely that non‐real‐time traffic (nrt‐traffic) will use the contention free period (CFP) that should be dedicated to traffic having higher priority such as rt‐traffic. Therefore, a modified PCF protocol called MPCF, which is based on hub polling and an integrated QoS differentiation, is presented in this paper. With the integrated QoS differentiation, MPCF can prioritize bandwidth requests according to service classes and QoS requirements. With hub polling, MPCF can reduce the bandwidth for control frames and improve the network throughput. A simple and accurate analytical model is derived and presented in this paper to calculate the system throughput of MPCF. Simulation results show that MPCF protocol is much better than PCF in terms of system capacity and rt‐traffic QoS guarantees. Copyright © 2008 John Wiley & Sons, Ltd.