异构无线网络中基于马尔可夫决策过程的区分业务接纳控制的研究

对异构无线网络中区分业务类型的接纳控制机制进行研究.分析了语音和数据2种典型业务在CDMA蜂窝网络和WLAN中的容量区域.基于马尔可夫决策过程理论,提出异构无线网络中区分业务类型的接纳控制理论模型,规定了不同类型业务的接纳控制行为并推导了系统状态转移概率.而且,进一步从用户角度对不同类型业务QoS要求和网络状态之间关系进行分析,提出一种基于模糊逻辑的接纳效用评估机制,在保证各类业务接入和切换成功率的基础上,推导出接纳效用最大的最优接纳控制策略.仿真表明,基于模糊逻辑的接纳效用评估能够有效反映网络状态动态变化对接纳控制的影响,最优接纳控制策略在平均接纳效用方面明显优于不考虑业务区分和用户移动性2种接纳控制机制,并且能严格保证各类业务的接入和切换成功率.     

一种基于对策模型的ATM网络连接接纳控制策略

本文先简述了ATM网络进行连接接纳控制(Connection Admission Control:CAC)的主要方法,其中主要综述了基于动态带宽分配的CAC策略,而后从合作对策模型的角度讨论业务间共享链路资源的公平性问题,提出一种基于时延带宽积的业务收益函数形式,并通过遗传算法求解待优化的对策函数,以决定对呼叫请求的接入或拒绝。仿真结果表明此方法能够更好地保证不同带宽和服务质量要求的业务共享网络资源的公平性。     

电话机、呼叫方式及其信令系统

本文研究了用于移动/无线网络的,具有服务质量(QoS)保证和动态信道分配的分布式接纳控制的性能。首先给出了采用动态分配信道的接纳控制的 QoS测度,之后导出了分布式呼叫接纳控制准则。所得结果给出了对于具有 QoS 保证的分布式接纳控制由最佳动态信道分配方案可得到的最佳的性能。参10     

一种优化无线多媒体业务接入允许控制和资源分配算法

无线网络中的多媒体业务具有很大吸引力。本文将多媒体业务分为实时业务和非实时业务,提出了一种呼叫接入控制优化算法CAC-RA,此算法通过采用马尔科夫方法,排队论和非线性规划模型,同时解决呼叫允许控制和资源优化分配问题。提出的利益函数考虑了最大利用资源,同时满足无线网络各类用户的QoS要求,同时尽量减少用户的资源重新分配的频率和幅度变化,仿真实验数据显示CAC-RA算法能较好地适应业务变化的网络,同时实现了较为理想的利益值,满足无线网络多媒体用户的QoS要求。     

基于优先级的IEEE802.16系统接纳控制算法研究

鉴于IEEE802.16标准中未对接纳控制机制提出定义,为了提高系统带宽利用率,在分析现有无线网络接纳控制技术的基础上,结合IEEE802.16的具体机制提出了一种基于业务优先级的接纳控制算法。相比于先到先服务的接纳机制,该算法严格区分业务优先级,为不同优先级业务预留带宽,以保证实时业务的服务质量(QoS)要求。利用NS2网络模拟软件对算法进行了仿真和性能评估。结果表明,本接纳控制算法可以较好地保障高优先级业务的实时性,同时在重负载情况下系统带宽利用率有了明显提高。     

流媒体业务呼叫接纳控制算法

为满足不同业务对服务质量的不同要求,提出了一种适用于无线流媒体业务的呼叫接纳控制算法。算法的思想是通过移动站和基站的协作和反馈控制,以剩余带宽和业务类型为依据进行接纳概率设计;通过互相协作的反馈控制,移动站可以获取系统的剩余可用带宽等级,依此调整业务的呼叫请求速率;仿真结果表明,该算法的输出变化较平滑、稳定,在呼叫阻塞概率、切换呼叫丢弃概率和带宽利用率方面有良好的综合性能。     

VoIP网络接纳控制机制必要性探讨

探讨了在基于IP技术的下一代电信网络中．是否有必要对VoIP实施基于资源的接纳控制。根据VoIP呼叫的带宽需求．对照具有接纳控制和无阻塞情况的资源规划方法．结合现阶段的网络资源部署情况，本文得出以下结论：在IP话音专网中，采用接纳控制机制可以大大节约带宽需求，但在资源充足的条件下可以不必实施接纳控制：在多业务IP骨干网络中，由于资源相对充足，而且VoIP业务的带宽比例较小，在采用区分服务并对话音业务进行最高优先级转发的前提下，不必实施接纳控制机制；在多业务城域网络的接入和汇聚结点，话音业务所需带宽资源所占比例不足5％，尽管接纳控制机制可以适当节约带宽．改善用户体验．但采用静态带宽配置的方法有利于降低设备和运营成本。     

基于决策理论的CDMA网络中多类业务的准入控制策略

准入控制是码分多址(CDMA)蜂窝网络中服务质量保证的一个关键技术。该文提出了一个基于半马尔可夫决策过程理论的最优准入控制策略来支持有服务质量要求的多类业务的无线CDMA网络。用线性规划方法求解最优策略,从而在满足服务质量约束要求的同时最大化信道利用率。另外,还使用了加权公平阻塞约束来灵活地实现服务质量要求。数值结果表明此最优策略可以获得比基于阈值的准入控制方案更好的性能。     

基于半马尔可夫链的WLAN/CDMA联合呼叫接入控制

下一代网络（NGN）将融合多种异构无线接入网络。为了在满足QoS限制下,最大化网络收益,在对WLAN／CDMA等效带宽的研究基础上,提出一种基于SMDP（半马尔可夫决策规划）的最优的联合呼叫接入控制（JCAC）方案,方案考虑了WLAN和CDMA网络间的相互影响,并将网络连接的联合呼叫控制问题等效成一个半马尔可夫决策过程,仿真表明方案相对于离散时间的MDP和在MDP基础上的JCAC算法具有明显的优势。     

ATM用户接入系统中呼叫接纳控制的实现

以ＡＴＭ用户接入系统为背景，介绍呼叫接纳控制（ＣＡＣ）的方法和工作过程。呼叫接纳控制是ＡＴＭ网络流量控制的基础。呼叫接纳控制模块收到呼叫接纳请求后，根据新连接的流量和业务质量要求以及现有网络资源情况，决定是否接受这一新连接。如果接受，就通知网络为新连接分配网络把新连接的流量参数送交用法接受这一新连的妆。如果接受，就通知网络为新连接网络资源，同时把新连接的流量参数送交用法参数控制（ＵＰＣ）模块进行流     

QoS provisioning in micro-cellular networks supporting multiple classes of traffic

We introduce an adaptive call admission control mechanism for wireless/mobile networks supporting multiple classes of traffic, and discuss a number of resource sharing schemes which can be used to allocate wireless bandwidth to different classes of traffic. The adaptive call admission control reacts to changing new call arrival rates, and the resource sharing mechanism reacts to rapidly changing traffic conditions in every radio cell due to mobility of mobile users. In addition, we have provided an analytical methodology which shows that the combination of the call admission control and the resource sharing schemes guarantees a predefined quality-of-service to each class of traffic. One major advantage of our approach is that it can be performed in a distributed fashion removing any bottlenecks that might arise due to frequent invocation of network call control functions.     

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.     

Virtual path control for ATM networks with call level quality ofservice guarantees

The configuration of virtual path (VP) connection services is expected to play an important role in the operation of large-scale asynchronous transfer mode (ATM) networks. A major research challenge is to understand the fundamental tradeoff between the network call throughput and the processing load on the signaling system and to provide an algorithm for VP capacity allocation that achieves an optimal network operating point while guaranteeing quality of service (QoS) at the call level and satisfies a priori bounds on the processing load of the call processors. We present a taxonomy of previous approaches to the problem and identify their strengths and weaknesses. Based on these observations, we provide an algorithm for the VP capacity allocation problem that satisfies nodal constraints on the call processing load and blocking constraints for each source-destination (SD) pair. The algorithm maximizes the network revenue under the above set of constraints and is parameterized by the number of traffic classes in the network, the method of presentation of networking resources, the admission control policy used in every link and VP, and the network routing scheme. Finally, we apply the algorithm to three sample networks and study several of its performance characteristics. In one case, we applied the calculated VP distribution to the Xunet ATM testbed and verified experimentally the predicted performance     

Call admission control in cellular networks: A reinforcement learning solution

In this paper, we address the call admission control (CAC) problem in a cellular network that handles several classes of traffic with different resource requirements. The problem is formulated as a semi‐Markov decision process (SMDP) problem. We use a real‐time reinforcement learning (RL) [neuro‐dynamic programming (NDP)] algorithm to construct a dynamic call admission control policy. We show that the policies obtained using our TQ‐CAC and NQ‐CAC algorithms, which are two different implementations of the RL algorithm, provide a good solution and are able to earn significantly higher revenues than classical solutions such as guard channel. A large number of experiments illustrates the robustness of our policies and shows how they improve quality of service (QoS) and reduce call‐blocking probabilities of handoff calls even with variable traffic conditions. Copyright © 2004 John Wiley & Sons, Ltd.     

Adaptive Call Admission Control for QoS/Revenue Optimization in CDMA Cellular Networks

In this paper, we show how online management of both quality of service (QoS) and provider revenue can be performed in CDMA cellular networks by adaptive control of system parameters to changing traffic conditions. The key contribution is the introduction of a novel call admission control and bandwidth degradation scheme for real-time traffic as well as the development of a Markov model for the admission controller. This Markov model incorporates important features of 3G cellular networks, such as CDMA intra- and inter-cell interference, different call priorities and soft handover. From the results of the Markov model the threshold for maximal call degradation is periodically adjusted according to the currently measured traffic in the radio access network. As a consequence, QoS and revenue measures can be optimized with respect to a predefined goal. To illustrate the effectiveness of the proposed QoS/revenue management approach, we present quantitative results for the Markov model and a comprehensive simulation study considering a half-day window of a daily usage pattern.     

基于多门限预留机制的自适应带宽分配算法

针对异构无线网络融合环境提出了一种基于多门限预留机制的自适应带宽分配算法,从而为多业务提供QoS保证。该算法采用多宿主传输机制,通过预设各个网络中不同业务的带宽分配门限,并基于各个网络中不同业务和用户的带宽分配矩阵,根据业务k支持的传输速率等级需求和网络状态的变化,将自适应带宽分配问题转化为一个动态优化问题并采用迭代方法来求解,在得到各个网络中不同业务和用户优化的带宽分配矩阵的同时,在带宽预留门限和网络容量的约束条件下实现网络实时吞吐量的最大化,以提高整个异构网络带宽的利用效率。数值仿真结果显示,所提算法能够支持满足QoS需求的传输速率等级,减小了新用户接入异构网络的阻塞概率,提高了平均用户接入率并将网络吞吐量最大提高40%。     

Bandwidth borrowing‐based QoS approach for adaptive call admission control in multiclass traffic wireless cellular networks

This paper proposes a QoS approach for an adaptive call admission control (CAC) scheme for multiclass service wireless cellular networks. The QoS of the proposed CAC scheme is achieved through call bandwidth borrowing and call preemption techniques according to the priorities of the traffic classes, using complete sharing of the available bandwidth. The CAC scheme maintains QoS in each class to avoid performance deterioration through mechanisms for call bandwidth degradation, and call bandwidth upgrading based on min–max and max–min policies for fair resource deallocation and reallocation, respectively. The proposed adaptive CAC scheme utilizes a measurement‐based online monitoring approach of the system performance, and a prediction model to determine the amount of bandwidth to be borrowed from calls, or the amount of bandwidth to be returned to calls. The simulation‐based performance evaluation of the proposed adaptive CAC scheme shows the strength and effectiveness of our proposed scheme. Copyright © 2011 John Wiley & Sons, Ltd.     

Adaptive control algorithms for decentralized optimal traffic engineering in the Internet

In this paper, we address the problem of optimal decentralized traffic engineering when multiple paths are available for each call. More precisely, given a set of possible paths for each call, we aim at distributing the traffic among the available paths in order to maximize a given utility function. To solve this problem, we propose a large family of decentralized sending rate control laws having the property that each of the members of this family "steers" the traffic allocation to an optimal operation point. The approach taken relies on the control theory concept of Sliding Modes. These control laws allow each ingress node to independently adjust its traffic sending rates and/or redistribute its sending rates among multiple paths. The only nonlocal information needed is binary feedback from each congested node in the path. The control laws presented are applicable to a large class of utility functions, namely, utility functions that can be expressed as the sum of concave functions of the sending rates. We show that the technique can be applied not only to usual rate adaptive traffic with multiple paths, but also to rate adaptive traffic with minimum service requirements and/or maximum allowed sending rate and to assured service with targeted rate guarantee, all allowing for multiple paths. It is also shown that these control laws are robust with respect to failures; i.e., they automatically reroute traffic if a link failure occurs. Finally, we provide some insight on how to choose the "right" control law. In particular, we provide a way of choosing a member of the family of control laws that reduces the sending rate oscillation caused by implementation constraints like delays and quantization. An example of application of the approach delineated in this paper is also presented. This example provides some insights on the implementation aspects and illustrates the robustness of the control laws developed in this paper.