Channel assignment with QoS guarantees for a multiclass multicode CDMA system

In a wireless system that supports multimedia services, each traffic requires different quality of service (QoS) at both communication on radio links and connection admission. We initially derive the uplink capacity satisfying the QoS constraint on radio links in a multiclass multicode code-division multiple-access (CDMA) system. Based on the derived capacity, the number of channel elements, which is one of the system resources, is determined. Then, we define the QoS parameters associated with connection processes. To guarantee the defined QoS at the connection level, under given channel elements, we propose a channel-assignment scheme with dynamic priority adjustment (DPA). The proposed scheme gives multipriority to different traffic classes. Real-time classes can preempt non-real-time classes with restricted preemptive priority. Such restriction is regulated by preemption-free code channels and a buffer threshold for non-real-time classes. Among real-time classes, different priorities are assigned to each traffic class by code reservation parameters. These multipriority parameters are dynamically adjusted in order to guarantee different QoS requirements. We analyze the DPA scheme by the matrix-geometric method, and evaluate the performance of each traffic class. The results show that the proposed scheme flexibly guarantees QoS depending on traffic loading condition and achieves high channel utilization.     

Integrated dynamic distributed routing and admission control in ATM networks

A node-by-node admission control and routing scheme for ATM networks is devised. The scheme is based on the subdivision of traffic into a number of classes, characterized by different performance requirements. At each network node, for all outgoing links, link capacity partitions are periodically assigned to the traffic classes, as the result of an optimization problem over a fixed time interval. Local access control rules compute the maximum number of connections of each class that a link can accept within the assigned capacity. Incoming call connection requests are forwarded in a hop-by-hop fashion. Each node traversed, first checks the presence of resources needed to accept a new connection and guarantee all quality of service (QoS) requirements. This is done by using the local access control rule. Then, it chooses the next node along the path on the basis of a distributed routing strategy. This minimizes a cost function accounting for local instantaneous information, as well as for aggregate information that is passed periodically among adjacent nodes. Two routing strategies are introduced. In the first scheme, a new call is rejected if, at a certain node along the path, there are not enough resources to guarantee QoS requirements, and no recovery mechanism is implemented. In the second scheme, an alternative path is looked for after the first failure. Simulation results are presented which show a comparison between the two proposed routing strategies. Comparison is also made between the proposed scheme and the other approaches. © 1997 John Wiley & Sons, Ltd.     

Providing deterministic quality-of-service guarantees on WDM optical networks

A major challenge in the design of future generation high-speed networks is the provision of guaranteed quality-of-service (QoS) for a wide variety of multimedia applications. In this paper we investigate the problem of providing QoS guarantees to real-time variable length messages (e.g., IP packets) in wavelength division multiplexing (WDM) optical networks. In particular, we propose a systematic mechanism comprised of admission control, traffic regulation, and message scheduling that provide guaranteed performance service for real-time application streams made up of variable-length messages. We formulate an analytical model based on the theory of max-plus algebra to evaluate the deterministic bounded message delay in a WDM network environment using our proposed QoS guarantee mechanism to determine the "schedulability conditions" of multimedia application streams, We also conduct a series of discrete-event and trace-driven simulations to verify the accuracy of the analytical model. The simulation results demonstrate that the analytic delay bound we obtained for our WDM optical network is valid and accurate.     

Bandwidth Reallocation for Bandwidth Asymmetry Wireless Networks Based on Distributed Multiservice Admission Control

This paper addresses when and how to adjust bandwidth allocation on uplink and downlink in a multi-service mobile wireless network under dynamic traffic load conditions. Our design objective is to improve system bandwidth utilization while satisfying call level QoS requirements of various call classes. We first develop a new threshold-based multi-service admission control scheme (DMS-AC) as the study base for bandwidth re-allocation. When the traffic load brought by some specific classes under dynamic traffic conditions in a system exceeds the control range of DMS-AC, the QoS of some call classes may not be guaranteed. In such a situation, bandwidth re-allocation process is activated and the admission control scheme will try to meet the QoS requirements under the adjusted bandwidth allocation. We explore the relationship between admission thresholds and bandwidth allocation by identifying certain constraints for verifying the feasibility of the adjusted bandwidth allocation. We conduct extensive simulation experiments to validate the effectiveness of the proposed bandwidth re-allocation scheme. Numerical results show that when traffic pattern with certain bandwidth asymmetry between uplink and downlink changes, the system can re-allocate the bandwidth on uplink and downlink adaptively and at the same time improve the system performance significantly.     

An FDD wideband CDMA MAC protocol with minimum-power allocation and GPS-scheduling for wireless wide area multimedia networks

A frequency division duplex (FDD) wideband code division multiple access (CDMA) medium access control (MAC) protocol is developed for wireless wide area multimedia networks. In order to reach the maximum system capacity and guarantee the heterogeneous bit error rates (BERs) of multimedia traffic, a minimum-power allocation algorithm is first derived, where both multicode (MC) and orthogonal variable spreading factor (OVSF) transmissions are assumed. Based on the minimum-power allocation algorithm, a multimedia wideband CDMA generalized processor sharing (GPS) scheduling scheme is proposed. It provides fair queueing to multimedia traffic with different QoS constraints. It also takes into account the limited number of code channels for each user and the variable system capacity due to interference experienced by users in a CDMA network. To control the admission of real-time connections, a connection admission control (CAC) scheme is proposed, in which the effective bandwidth admission region is derived based on the minimum-power allocation algorithm. With the proposed resource management algorithms, the MAC protocol significantly increases system throughput, guarantees BER, and improves QoS metrics of multimedia traffic.     

Efficient protocols for multimedia streams on WDMA networks

This paper introduces a new approach to integrate different types of medium access control (MAC) protocols into a single wavelength-division-multiplexing (WDM) network system. The WDM network is based on a passive star coupler, and the purpose of integrating different MAC protocols is to efficiently accommodate various types of multimedia traffic streams with different characteristics and quality of service demands. Our integrated MAC protocol is termed multimedia wavelength-division multiple-access (M-WDMA). Three types of multimedia traffic streams are considered in this paper: constant-bit-rate traffic and two classes of variable-bit-rate traffic. Accordingly, three tunable transmitters and one fixed home channel receiver are used in the design of each WDM node. The transmitters transmit the three types of multimedia traffic streams in a pipeline fashion so as to overcome the tuning time overhead and to support parallel transmissions of traffic streams that emerge simultaneously. We further incorporate a dynamic bandwidth allocation scheme that dynamically adjusts the portions of bandwidth occupied by the three types of traffic streams according to their demands. Consequently the M-WDMA protocol achieves high utilization and efficiently adapts to the demands of the multimedia streams so as to guarantee their QoS. The performance of the M-WDMA is evaluated through a simple analytical model and extensive discrete-event simulations. It is shown that the M-WDMA can satisfy the QoS requirements of various mixes of multimedia traffic streams even under very stringent requirements. Moreover, we show that the M-WDMA outperforms conventional MAC protocols for WDM networks. As a result, we expect M-WDMA to be a good multimedia MAC candidate protocol for future-generation WDM networks.     

Capacity design and performance of call admission control incellular CDMA systems

Since code-division multiple-access (CDMA) capacity is interference limited, call admission control (CAC) must guarantee both a grade of service (GoS), i.e., the blocking rate, and a quality of service (QoS), i.e., the loss probability of communication quality. This paper describes the development of a new capacity design method based on these two concepts. Theoretical expressions for GoS and QoS as functions of traffic intensity and CAC thresholds are first derived from the traffic theory viewpoint, and then a design method using these expressions is presented. At that time, two strategies for CAC are assumed. One is based on the number of users, and the other is based on the interference level. Computer simulation results are presented that strongly support the proposed design method. Furthermore, numerical examples and a performance comparison of the two strategies considering various propagation parameters, nonuniform traffic distributions, and various transmission rates are shown     

A traffic control system for IEEE 802.11 networks based on available bandwidth estimation

To support Quality of service (QoS)‐sensitive applications like real‐time video streaming in IEEE 802.11 networks, a MAC layer extension for QoS, IEEE 802.11e, has been recently ratified as a standard. This MAC layer solution, however, addresses only the issue of prioritized access to the wireless medium and leaves such issues as QoS guarantee and admission control to the traffic control systems at the higher layers. This paper presents an IP‐layer traffic control system for IEEE 802.11 networks based on available bandwidth estimation. We build an analytical model for estimating the available bandwidth by extending an existing throughput computation model, and implement a traffic control system that provides QoS guarantees and admission control by utilizing the estimated available bandwidth information. We have conducted extensive performance evaluation of the proposed scheme via both simulations and measurements in the real test‐bed. The experiment results show that our estimation model and traffic control system work accurately and effectively in various network load conditions without IEEE 802.11e. The presence of IEEE 802.11e will allow even more efficient QoS provision, as the proposed scheme and the MAC layer QoS support will complement each other. Copyright © 2006 John Wiley & Sons, Ltd.     

EPON和WiMAX融合架构下带宽分配和调度机制的研究

以太网无源光网络(EPON)和IEEE 802.16(WiMAX)的融合网络在固定移动混合接入网中被认为是很有前景的接入方式.文中提出了3种WiMAX无线网络与EPON网络系统融合架构,融合系统同时具有光网络的高带宽和无线网络的灵活性.为了在接入网中支持QoS,本文为融合结构提出了一种动态带宽分配算法(DBA)和调度机...     

Efficient call admission control for heterogeneous services inwireless mobile ATM networks

An efficient call admission control scheme for handling heterogeneous services in wireless ATM networks is proposed. Quality-of-service provisioning of jitter bounds for constant bit rate traffic and delay bounds for variable bit rate traffic is used in the CAC scheme to guarantee predefined QoS levels for all traffic classes. To reduce the forced handoff call dropping rate, the CAC scheme gives handoff calls a higher priority than new calls by reserving an appropriate amount of resources for potential handoff calls. Resource reservation in the CAC scheme makes use of user mobility information to ensure efficient resource utilization. Simulation results show that the proposed CAC scheme can achieve both low handoff call dropping rate and high resource utilization     

Dynamic connection provisioning with shared protection in IP/WDM networks

Internet protocol (IP) traffic connections arrive dynamically at wavelength‐division multiplexing (WDM) network edges with low data rates compared with the wavelength capacity, availability, and quality‐of‐service (QoS) constraints. This paper introduces a scheme to be integrated into the control and management plane of IP/WDM networks to satisfy the availability and QoS required for IP traffic connections bundled onto a single wavelength (lightpath) in WDM networks protected by shared‐backup path protection (SBPP). This scheme consists of two main operations: (i) routing multi‐granular connections and traffic grooming policies, and (ii) providing appropriate shared protection on the basis of subscribers’ service‐level agreements in terms of data rate, availability, and blocking probability. Using the Markov chain process, a probabilistic approach is developed to conceive connection blocking probability models, which can quantify the blocking probability and service utilization of M:N and 1:N SBPP schemes. The proposed scheme and developed mathematical models have been evaluated in terms of bandwidth blocking ratio, availability satisfaction rate, network utilization, and connection blocking probability performance metrics. The obtained research results in this paper provide network operators an operational setting parameter, which controls the allocation of working and backup resources to dynamic IP traffic connections on the basis of their priority and data rate while satisfying their requirements in terms of bandwidth and availability. Copyright © 2013 John Wiley & Sons, Ltd.     

Traffic engineering in a multipoint-to-point network

The need to guarantee quality-of-service (QoS) to multimedia applications leads to a tight integration between the routing and forwarding functions in the Internet. multiprotocol label switching tries to provide a global solution for this integration. In this context, multipoint-to-point (m2p) networks appear as a key architecture since they provide a cheaper way to connect edge nodes than point-to-point connections. M2p networks have been mainly studied for their load balancing ability. In this paper, we go a step further: we propose and evaluate a traffic management scheme that provides deterministic QoS guarantees for multimedia sources in an m2p network. We first derive an accurate upper bound on the end-to-end delay in an m2p architecture based on the concept of additivity. Broadly speaking, an m2p network is additive if the maximum end-to-end delay is equal to the sum of local maximum delays. We then introduce two admission control algorithms for additive networks: a centralized algorithm and a distributed algorithm and discuss their complexity and their scalability     

Per-Stream QoS and Admission Control in Ethernet Passive Optical Networks (EPONs)

Ethernet passive optical networks (EPONs) are designed to deliver services for numerous applications such as voice over Internet protocol, standard and high-definition video, video conferencing (interactive video), and data traffic. Various dynamic bandwidth allocation and intra-optical network unit (ONU) scheduling algorithms have been proposed to enable EPONs to deliver differentiated services for traffic with different quality of service (QoS) requirements. However, none of these protocols and schedulers can guarantee bandwidth for each class of service nor can they protect the QoS level required by admitted real-time traffic streams. In this paper, we propose the first framework for per-stream QoS protection in EPONs using a two-stage admission control (AC) system. The first stage enables the ONU to perform flow admission locally according to the bandwidth availability, and the second stage allows for global AC at the optical line terminal. Appropriate bandwidth allocation algorithms are presented as well. An event-driven simulation model is implemented to study the effectiveness of the proposed schemes in providing and protecting QoS.     

Radio resource management for cellular CDMA systems supporting heterogeneous services

A novel radio resource management (RRM) scheme for the support of packet-switched transmission in cellular CDMA systems is proposed by jointly considering the physical, link, and network layer characteristics. The proposed resource management scheme is comprised of a combination of power distribution, rate allocation, service scheduling, and connection admission control. Power distribution allows individual connections to achieve their required signal-to-interference-plus-noise ratio, while rate allocation guarantees the required delay/jitter for real-time traffic and the minimum transmission rate requirement for non-real-time traffic. Efficient rate allocation is achieved by making use of the randomness and burstiness; of the packet generation process. At the link layer, a packet scheduling scheme is developed based on information derived from power distribution and rate allocation to achieve quality of service (QoS) guarantee. Packet scheduling efficiently utilizes the system resources in every time slot and improves the packet throughput for non-real-time traffic. At the network layer, a connection admission control (CAC) scheme based on the lower layer resource allocation information is proposed. The CAC scheme makes use of user mobility information to reduce handoff connection dropping probability (HCDP). Theoretical analysis of the grade of service performance, in terms of new connection blocking probability, HCDP, and resource utilization, is given. Numerical results show that the proposed RRM scheme can achieve both effective QoS guarantee and efficient resource utilization.     

Intra-ONU bandwidth scheduling in Ethernet passive optical networks

Quality-of-service (QoS) support in Ethernet passive optical networks (EPON) is a crucial concern. However, most studies have only focused on optical line terminal (OLT) capacity allocation amongst multiple optical network units (ONU), and the further issue of intra-ONU allocation remains open. In this work a novel decentralized intra-ONU solution is presented using virtual-time schedulers. Results confirm good performance for a wide range of input traffic classes and loads.     

Admission control in time-slotted multihop mobile networks

The emergence of nomadic applications have generated a lot of interest in next-generation wireless network infrastructures which provide differentiated service classes. So it is important to study how the quality of service (QoS), such as packet loss and bandwidth, should be guaranteed. To accomplish this, we develop am admission control scheme which can guarantee bandwidth for real-time applications in multihop mobile networks. In our scheme, a host need not discover and maintain any information of the network resources status on the routes to another host until a connection request is generated for the communication between the two hosts, unless the former host is offering its services as an intermediate forwarding station to maintain connectivity between two other hosts. This bandwidth guarantee feature is important for a mobile network to interconnect wired networks with QoS support. Our connection admission control scheme can also work in a stand-alone mobile ad hoc network for real-time applications. This control scheme contains end-to-end bandwidth calculation and bandwidth allocation. Under such a scheme, the source is informed of the bandwidth and QoS available to any destination in the mobile network. This knowledge enables the establishment of QoS connections within the mobile network and the efficient support of real time applications. In the case of ATM interconnection, the bandwidth information can be used to carry out an intelligent handoff between ATM gateways and/or to extend the ATM virtual circuit service to the mobile network with possible renegotiation of QoS parameters at the gateway. We examine via simulation the system performance in various QoS traffic flows and mobility environments     

WDM光网络的多优先级业务疏导机制

IP over WDM网络中,业务疏导能有效提高波长带宽利用率.然而,单一化的业务疏导机制难以满足不同业务的QoS要求,也很难做到经济合理地使用光路.提出了一种支持多优先级业务的疏导机制,该机制根据光路传输的时延和丢包特性来选择恰当的疏导路径,同时,该机制结合了抢占和流量分割技术,能有效地实现流量分割和多路抢占,降低了业务的阻塞概率.仿真结果显示,该疏导机制在保证业务QoS的同时,降低了高优先级业务的阻塞概率;在业务负载低时,能有效减少抢占.     

优化EPON对本地P2P业务承载能力的研究

P2P流量已成为网络中的主要流量,但现有EPON系统不能很好的承载本地P2P业务.文中从MPCP协议的角度对逻辑链路标签及其过滤规则进行扩展,使本地P2P数据包不需经OLT端二层交换即可实现下行转发,从而大大改善了P2P业务的QoS.并以此方案为基础,提出改进EPON的DBA算法,设置专门的P2P时隙,实现P2P业务的全光域转发.两种方案的建模仿真结果表明,两者均能明显改善EPON对本地P2P业务的承载能力.     

一种用于提供QoS保证的准入控制方法

本文推导了ON/OFF马尔可夫数据流的资源分配与延迟分布、丢失率的关系,在此基础上进行可准入性测试,并根据流的优先权大小给出一种优化的准入控制方法,可为各类流提供服务质量(QoS)保证.最后通过算例说明该方法的有效性.     

Service based CAC with QoS guarantee in mobile wireless cellular networks

The increasing variety and complexity of traffic in today's mobile wireless networks means that there are more restrictions placed on a network in order to guarantee the individual requirements of the different traffic types and users. Call admission control (CAC) plays a vital role in achieving this. In this paper, we propose a CAC scheme for multiple service systems where the predicted call usage of each service is used to make the admission decision. Our scheme enables real‐time traffic to be transmitted using shared bandwidth without quality of service (QoS) requirements being exceeded. This ensures that the utilization of the available wireless bandwidth is maximized. Information about the channel usage of each service is used to estimate the capacity of the cell in terms of the number of users that can achieve a certain bit error rate (BER). Priorities assigned to each service are used to allocate the network capacity. An expression for the handoff dropping probability is derived, and the maximum acceptance rate for each service that results in the estimated dropping probability not exceeding its QoS requirements is calculated. Each call is then accepted with equal probability throughout the duration of a control period. Achieved QoS during the previous control period is used to update the new call acceptance rates thus ensuring the dropping probability remains below the specified threshold. Simulations conducted in a wideband CDMA environment with conversational, streaming, interactive and background sources show that the proposed CAC can successfully meet the hard restraint on the dropping probability and guarantee the required BER for multiple services. Copyright © 2005 John Wiley & Sons, Ltd.