WiMAX网络中信噪比与带宽结合的接纳控制算法

呼叫接纳控制（CAC）是宽带无线接入网络无线资源管理中一个重要的组成部分,其中策略设计的好坏直接影响着网络的性能和资源利用率。针对现有基于WiMAX的接纳控制算法仅考虑了带宽作为接纳控制的标准,提出一种结合带宽和信噪比的接纳控制算法,在考虑小区带宽因素的同时能兼顾考虑接纳后业务的信噪比情况。仿真结果表明,结合带宽和信噪比的接纳控制算法可以有效的降低系统中呼叫的掉线率,提高系统性能。     

Elastic threshold-based admission control for QoS satisfaction with reward optimization for servicing multiple priority classes in wireless networks

We analyze performance characteristics of a class of call admission control (CAC) algorithms designed for servicing multiple priority classes in wireless networks with the goal of quality of service (QoS) satisfaction and reward optimization. By reward, we mean some sort of “value” obtained by the system as a result of servicing multiple priority classes. In this paper we design and evaluate the performance of a new algorithm, elastic threshold-based CAC, in terms of the maximum reward obtainable with QoS satisfaction from servicing multiple priority classes with distinct QoS requirements, and compare it with existing partitioning, threshold, and spillover CAC algorithms. We also develop a heuristic-based search method to determine the best threshold-value sets used for multiple service classes by sequentially adjusting these thresholds based on the reward and rejection rate obtainable vs. QoS constraints of each service class. We demonstrate through test cases and simulation that elastic threshold-based CAC outperforms existing CAC algorithms for QoS satisfaction and reward optimization in solution optimality for serving multiple QoS service classes in wireless networks.     

A cross-layer elastic CAC and holistic opportunistic scheduling for QoS support in WiMAX

QoS provisioning is an important issue in the deployment of broadband wireless access networks with real-time and non-real-time traffic integration. An opportunistic MAC (OMAC) combines cross-layer design features with opportunistic scheduling scheme to achieve high system utilization while providing QoS support to various applications. A single scheduling algorithm cannot guarantee all the QoS requirements of traffics without the support of a suitable CAC and vice versa. In this paper, we propose a cross-layer MAC scheduling framework and a corresponding opportunistic scheduling algorithm in tandem with the CAC algorithm to support QoS in WiMAX point-to-multipoint (PMP) networks. Extensive experimental simulations have been carried out to evaluate the performance of our proposal. The simulation results show that our proposed solution can improve the performance of WiMAX networks in terms of packet delay, packet loss rate and throughput. The proposed CAC scheme can guarantee the admitted connections to meet their QoS requirements.     

Power-based multi-cell call admission control scheme for wideband-CDMA systems

Wideband code division multiple access (WCDMA) systems are interference-limited. When a WCDMA system operates at nearly full capacity, admitting a new user may affect the stability of the system. Therefore, the proper call admission control (CAC) is crucial and should balance between quality of service (QoS) requirements for the new user as well as for the existing users and the required high capacity. In this paper, we investigate this trade-off in the uplink direction using a power-based multi-cell admission control (MC-AC) algorithm. Multimedia services are considered with different QoS requirements in this algorithm. Different traffic scenarios are also considered. Simulation results reveal that the proposed MC-AC algorithm has many advantages over single-cell admission control (SC-AC) in terms of the overall stability of the system and the total system throughput.     

Connection admission control of ATM network using integrated MLP and fuzzy controllers

This paper presents a new approach to the problem of call admission control (CAC) of variable bit rate (VBR) traffic in an asynchronous transfer mode (ATM) network. Our approach employs an integrated neural network and fuzzy controller to implement the CAC controller. This scheme capitalizes on the learning ability of a neural network and the robustness of a fuzzy controller. Experiments show that this scheme is able to achieve high throughput and low cell loss while achieving fairness among different classes of VBR traffic. For comparison, we have also implemented four other CAC schemes: (1) peak bandwidth method, (2) equivalent bandwidth method, (3) average bandwidth method and (4) neural network quality of service (QoS) predictor. Results of these experiments are presented in this paper.     

接纳控制算法现状分析

3G业务的多样性,QoS的严格性以及无线资源的稀缺性等因素对呼叫接纳控制技术提出了更高的要求。对呼叫接纳控制算法进行概述,讨论了CDMA系统中常用的和移动通信网中具有代表性的呼叫接纳控制算法。     

适合于移动多媒体网络的呼叫接纳控制算法

移动多媒体网络应该能够同时支持传统的数据业务和实时交互式多媒体业务,并能够为用户提供QoS保证.在无线移动网中提供QoS保证,呼叫接纳控制扮演着重要的角色.通过对呼叫接纳算法中资源预留方案进行了分析总结,提出了一种适合于移动多媒体网络的自适应呼叫接纳控制算法.     

Integration of admission,congestion, and peak power control in QoS-aware clusters

Admission, congestion, and peak power control mechanisms are essential parts of a cluster network design for supporting integrated traffic. While an admission control algorithm helps in delivering the assured performance, a congestion control algorithm regulates traffic injection to avoid network saturation. Peak power control forces to meet pre-specified power constraints while maintaining the service quality by regulating the injection of packets. In this paper, we propose these control algorithms for clusters, which are increasingly being used in a diverse set of applications that require QoS guarantees. The uniqueness of our approach is that we develop these algorithms for wormhole-switched networks, which have been used in designing clusters. We use QoS-capable wormhole routers and QoS-capable network interface cards (NICs), referred to as Host Channel Adapters (HCAs) in InfiniBand™ Architecture (IBA), to evaluate the effectiveness of these algorithms. The admission control is applied at the HCAs and the routers, while the congestion control and the peak power control are deployed only at the HCAs. A mixed workload consisting of best-effort, real-time, and control traffic is used to investigate the effectiveness of the proposed schemes.     

An optimal approach to the connection admission control problem

The paper considers the connection admission control (CAC), which is a key resource management procedure, and proposes a solution to the problem based on modelling and control methodologies. The CAC problem will be formulated as an optimal control problem subject to a set of constraints. As a matter of fact, the proposed controller, modelling the CAC mechanism, computes the above-mentioned control variables so that (i) a set of proper constraints, which model the quality of service (QoS) requirements (link availability, blocking probability and dropping probability), are respected and (ii) a proper performance index, which models the exploitation degree of the available bandwidth, is maximized. The proposed CAC successfully compares with other CACs proposed in the literature, and in particular significantly extends the upper limit of the accepted traffic rate.     

Integration of pricing with call admission control to meet QoS requirements in cellular networks

Call admission control (CAC) plays a significant role in providing the desired quality of service (QoS) in cellular networks. We investigate the role of pricing as an additional dimension of the call admission control process in order to efficiently and effectively control the use of wireless network resources. First, we prove that, for a given wireless network, there exists a new call arrival rate which can maximize the total utility of users while maintaining the required QoS. Based on this result and observation, we propose an integrated pricing and call admission control scheme where the price is adjusted dynamically based on the current network conditions in order to alleviate the problem of congestion. Our proposed integrated approach implicitly implements a distributed user-based prioritization mechanism by providing negative incentives according to the current network conditions and therefore shaping the aggregate traffic in the network. We compare the performance of our approach in terms of congestion prevention, achievable total user utility, and obtained revenue, with the corresponding results of conventional systems where pricing is not taken into consideration in the call admission control process. These performance results verify the considerable improvement that can be achieved by the integration of pricing in the call admission control process in cellular networks.     

一种基于模糊逻辑的多媒体组播准入控制机制

组播呼叫准入控制(CAC)是下一代网络（NGN）QoS的关键问题,在分析已有CAC机制的基础上,提出一种基于模糊逻辑的组播准入控制机制(FMAC),以服务质量、网络拥塞状态参数、可用容量和等效带宽作为模糊输入,经过模糊推理判断是否接受新的组播呼叫。仿真结果表明,FMAC在保持高的网络利用率的同时,能满足用户的QoS要求,并能保持较低的阻塞率,具有扩展性好、实现简单的特点。     

一种面向WiMAX的呼叫接纳控制算法

提出一种在WiMAX系统资源紧张时,使接纳率和资源利用率最大化的呼叫接纳控制CAC(Call Admission Control)算法。算法基于经济学概念,利用基尼系数(Gini Coefficient)给出了接纳控制模型,并用修正的sigmoid函数计算接纳概率。根据接纳概率决定是否接纳新到业务。仿真结果表明,算法与典型的截止优先权算法相比,在系统繁忙时系统接纳率和资源利用率都有较大提高。     

Dynamic admission control in hybrid QoS networks with WiFi access

Recent developments in the IEEE 802.11 standardizations[1] have been successful to offer high-speed data services. Hence, traffic classes (e.g. VoIP or video-conference) with different QoS requirements will be provided in future wireless LANs (WLAN). Sinc…     

Call admission control in multiservice high altitude platform (HAP) W-CDMA cellular systems

Of the various radio resource management functions, in this paper we focus on call admission control (CAC). We propose a CAC scheme for multiservice High Altitude Platform (HAP) wideband code division multiple access (W-CDMA) cellular systems that caters for multimedia services. HAPs have known increasing popularity during the past few years and are expected to play a pivotal role in the telecommunications arena by virtue of their appealing features. We first study the uplink capacity of a multiservice HAP W-CDMA cellular system taking into consideration power control imperfections and evaluate the degradation that a new call induces in the quality of service of ongoing calls. Based on the obtained statistics, we then develop a CAC scheme that takes account of power control imperfections and user mobility and compare it to a CAC scheme that is based on instantaneous energy per bit to noise power spectral density ratio (E_b/N₀) measurements. Additionally, we examine these algorithms for two different criteria that apply to both new and handoff call requests. The first criterion is based on the minimum E_b/N₀ of the first tier cells, while the second bases its decision upon the mean E_b/N₀ of the cells of the first tier. Simulation studies further document and confirm the positive characteristics of the proposed CAC scheme.     

Design and performance analysis of an inductive QoS routing algorithm

Routing mechanism is key to the success of large-scale, distributed communication and heterogeneous networks. Consequently, computing constrained shortest paths is fundamental to some important network functions such as QoS routing and traffic engineering. The problem of QoS routing with multiple additive constraints is known to be NP-complete but researchers have been designing heuristics and approximation algorithms for multi-constrained paths algorithms to propose pseudo-polynomial time algorithms. This paper introduces a polynomial time approximation quality of service (QoS) routing algorithm and constructs dynamic state-dependent routing policies. The proposed algorithm uses an inductive approach based on trial/error paradigm combined with swarm adaptive approaches to optimize lexicographically various QoS criteria. The originality of our approach is based on the fact that our system is capable to take into account the dynamics of the network where no model of the network dynamics is assumed initially. Our approach samples, estimates, and builds the model of pertinent aspects of the environment which is very important in heterogeneous networks. The algorithm uses a model that combines both a stochastic planned pre-navigation for the exploration phase and a deterministic approach for the backward phase. Multiple paths are searched in parallel to find the K best qualified ones. To improve the overall network performance, a load adaptive balancing policy is defined and depends on a dynamic traffic path probability distribution function. We conducted a performance analysis of the proposed QoS routing algorithm using OPNET based on a platform simulated network. The obtained results demonstrate substantial performance improvements as well as the benefits of learning approaches over networks with dynamically changing traffic.     

基于测量的接纳控制算法研究综述

介绍了计算机网络QoS研究中基本网络模型、服务模型以及在接纳控制研究中常用的流量描述模型.重点综述了在连接接纳控制研究中占重要地位的基于测量的接纳控制算法,详尽描述和分析了各主要算法的思想、数学模型、应用环境及优缺点,并对各主要算法进行了比较,同时介绍了当前接纳控制研究的一些新进展,包括集成服务网络,区分服务网络及ATM QoS的基于测量的接纳控制研究,并对未来接纳控制研究进行了展望.     

基于马尔科夫链的联合呼叫接入控制算法

异构网络的接入策略与网络资源管理效率紧密相关;同时,网络复杂性与网络资源竞争性直接影响到用户服务质量。针对异构网络接入控制存在的切换掉话率和呼叫阻塞率高、资源利用率低等问题,提出了基于马尔科夫链的联合呼叫接入控制算法。接入控制算法为切换呼叫业务、实时业务动态地预留了一定的带宽资源,根据不同业务设置带宽降级因子来决定是否释放带宽;同时,根据用户偏好和不同业务的QoS要求,构建了呼叫接入控制效用函数,利用马尔科夫链进行了建模分析。仿真表明,算法提高了网络资源利用率,降低了系统复杂度,满足了各类业务的QoS要求。     

Efficient heuristics for energy-aware routing in networks with bundled links

Current networks are typically over-provisioned to ensure low delays, redundancy and reliability. These Quality of Service (QoS) guarantees are typically achieved using high end, high power network equipments. Their use, however, has led to concerns regarding green house gas emissions, which garnered a lot of attention recently and have resulted in a number of global initiatives aim at reducing the carbon footprint of Internet Service Providers (ISPs). These initiatives have motivated ISPs and researchers to design novel network algorithms and hardware that scale the usage or active time of a network according to traffic load. To this end, this paper considers the problem of shutting down a subset of bundled links during off-peak periods in order to minimize energy expenditure. Unfortunately, identifying the cables that minimize this objective is an NP-complete problem. Henceforth, we propose several practical heuristics based on Dijkstra’s algorithm and Yen’s k-shortest paths algorithm. We evaluated our heuristics on the Abilene network – with both real and synthetic traffic matrices and several larger random topologies with various loads. Our results show that the proposed heuristics to be effective and efficient. Moreover, our approaches could potentially reduce the energy usage of cables used in the Abilene network by up to 56.7%, assuming the traffic demands recorded on September 5, 2004.     

一种新型的异构无线网络呼叫接纳控制算法研究

在CDMA2000蜂窝网络和WLAN组成的异构无线网络中,呼叫接纳控制算法对于提高系统资源的利用率有着非常重要的作用。根据WLAN的网络负载情况和移动用户的速度来判决是否接入WLAN;提出一种基于概率机制的CAC算法,WLAN能够限制来自于蜂窝网的VHO呼叫,减少不必要的VHO处理负荷;对新呼叫阻塞率和DVHO呼叫阻塞率进行理论分析和推导。仿真结果表明,该CAC算法能够减少不必要的重复上下垂直切换,同时将DVHO呼叫阻塞率控制在可接受的范围内。算法保证了较高的系统吞吐量,提高了系统整体性能。