Utility‐based probabilistic call admission control for complete fairness in wireless networks

Resource reservation or the other prioritization strategies adopted by Call Admission Control (CAC) schemes in wireless networks lead to unfair resource allocation to users belonging to different service classes (SCs) due to high divergence among the respective call blocking probabilities (CBPs). In this paper, we propose dynamic optimization of probabilistic CAC (P‐CAC) schemes to assure CAC fairness among users of different SCs in wireless networks. The approach is based on users utility combined with fairness optimization, aiming at dynamically determining the probability value in the P‐CAC scheme. This optimal probability is adjusted to network ongoing traffic, CBPs of each SC, prioritization levels characterizing the SCs supported, and the users risk aversion, which reflects their behavior toward the perceived QoS. The existence and uniqueness of the optimal probability that leads to absolute fairness among the users of a wireless network are proven. Copyright © 2012 John Wiley & Sons, Ltd.     

A call admission control strategy for multiservice wireless cellular packet networks

A simple connection control system for multiservice cellular wireless networks is presented. Mobile stations are classified depending on the traffic they generate (e.g., voice, data). Within each class, two subclasses are also identified: stations which have originated inside the cell and stations which come from adjacent cells. The connection control mechanism is carried out by considering a number of priorities among the various classes and their subclasses. It works on two levels: static and dynamic. The static level looks at packet-level quality of service (QoS), such as cell loss and delay, while the dynamic level takes care of connection dynamics and allows the load of the system to be driven with respect to the various subclasses. Results that illustrate the performance of this control mechanism are presented.     

蜂窝无线通信网络呼叫允许控制分析

无线网络中由于用户的移动性、频谱资源的缺乏以及信道的衰落,使无线网络的服务质量的供给成为一个日益严峻的问题。呼叫允许控制(CAC)是无线资源管理中的重要组成部分,是一种保证服务质量和网络资源利用率的重要机制。总结了CAC领域的研究成果,对蜂窝无线通信网络的CAC方案进行了分析,指出了目前CAC研究中存在的问题,并探讨了今后的研究方向。     

无线移动网中呼叫接纳控制模型分析

新一代无线网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。在无线网中提供QoS保证，呼叫接纳控制扮演着重要的角色。对已有的呼叫接纳控制方面的研究成果进行了归纳、总结和分析，以期得出适合于无线移动多媒体网络的呼叫接纳控制模型。为适应当前的多媒体应用，侧重于对和适应性带宽分配相结合的接纳控制模型的分析。另外，介绍了与价格机制相结合的接纳控制模型，经济学概念的引入，为我们解决问题提供了一种新的视角。     

Call admission control for capacity-varying networks

Many networks, such as Non-Geostationary Orbit Satellite (NGOS) networks and networks providing multi-priority service using advance reservations, have capacities which vary over time for some or all types of calls carried on these networks. For connection-oriented networks, Call Admission Control (CAC) policies which only use current capacity information may lead to excessive and intolerable dropping of admitted calls whenever the network capacity decreases. Thus, novel CAC policies are required for these networks. Three such CAC policies are discussed, two for calls with exponentially distributed call holding times and one for calls whose holding time distributions have Increasing Failure Rate (IFR) functions. The Admission Limit Curve (ALC) is discussed and shown to be a constraint limiting the conditions under which any causal CAC policy may admit calls and still meet call dropping guarantees on an individual call basis. We demonstrate how these CAC policies and ALC represent progressive steps in developing optimal CAC policies for calls with exponentially distributed call holding times, and extend this process to the more general case of calls with IFR call holding times.     

适应自相似业务流量模型的CAC算法研究

分析了呼叫接纳控制算法研究的现状，提出一种适应自相似业务流量模型的呼叫接纳控制算法，在接纳判决过程中引入概率接纳机制。理论分析和仿真结果验证了算法的可行性和在自相似业务流量模型下相对于传统呼叫接纳控制算法的优越性。     

Adaptive call admission control in 3GPP LTE networks

In this article, we propose new methods to reduce the handoff blocking probability in the 3rd Generation Partnership Project Long Term Evolution wireless networks. This reduction is based on an adaptive call admission control scheme that provides QoS guarantees and gives the priority of handoff call over new call in admission. The performance results of the proposed schemes are compared with other competing methods using simulation analysis. Simulation results show the major impact on the performance of the 3rd Generation Partnership Project Long Term Evolution network, which is reflected in increased resource utilization ratio to (99%) and in the ability in satisfying the requirements of QoS in terms of call blocking probability (less than 0.0628 for Voice over IP service) and dropping probability rate (less than 0.0558).Copyright © 2012 John Wiley & Sons, Ltd.     

Novel congestion control approach in wireless multimedia sensor networks

Data generated in wireless multimedia sensor networks (WMSNs) may have different importance and it has been claimed that the network exert more efforts in servicing applications carrying more important information. Nevertheless, importance of packets cannot generally be accurately represented by a static priority value. This article presents a dynamic priority based congestion control (DPCC) approach that makes two major innovations in WMSNs. First, DPCC employs dynamic priority to represent packet importance. Second, it prioritizes the local traffic of motes near the base station when WMSN is highly congested. Simulation results confirm the superior performance of the proposed approach with respect to energy efficiency, loss probability and latency as well.     

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.     

Dynamic pricing for load‐balancing in user‐centric joint call admission control of next‐generation wireless networks

Next‐generation wireless networks (NGWN) will be heterogeneous, comprising of a number of radio access technologies (RATs) co‐existing in the same geographical area. In NGWN, joint call admission control (JCAC) algorithms are required to select the most appropriate RAT for each incoming call. It is envisaged that these JCAC algorithms will be user‐centric (i.e. will consider users' preferences in making RAT selection decisions) in order to enhance user satisfaction. However, user‐centric JCAC algorithms can lead to highly unbalanced traffic load among the available RATs in NGWN because users act independently, and most of them may prefer to be connected through a particular RAT. Highly unbalanced traffic load in NGWN will result in high overall call blocking/dropping probability and poor radio result utilization. To address this problem, we propose dynamic pricing for balancing traffic load among available RATs in heterogeneous wireless networks where users' preferences are considered in making RAT selection decisions. By dynamically adjusting the service price in each of the available RATs, the proposed user‐centric JCAC scheme evens out the unbalanced traffic load caused by independent users' preferences. The JCAC scheme uses fuzzy multiple attribute decision‐making (MADM) technique to select the most appropriate RAT for each incoming call. We develop a Markov model to evaluate the overall call blocking/dropping probability and percentage load in each RAT in heterogeneous wireless networks. Performance of the proposed JCAC scheme is compared with that of a scheme that does not use dynamic pricing. Simulation results are given to show the effectiveness of the proposed JCAC scheme. Copyright © 2009 John Wiley & Sons, Ltd.     

Bandwidth guaranteed call admission in TDMA/CDMA ad hoc wireless networks

This paper first studied the timeslot assignment problem in time division multiple access/code division multiple access (TDMA/CDMA) wireless ad hoc networks. Given a path P, we prove that a timeslot assignment providing one unit of bandwidth on P can be found in O(P) time if such an assignment exists. The results have been extended to the case that P can provide two units of bandwidth. Based on the timeslot assignment for the special cases, an efficient slot assignment algorithm with O(P²k) is proposed for general cases, where k is the number of slots in a TDMA frame. Then, the timeslot assignment algorithm is integrated into a quality of service (QoS) call admission scheme for QoS call requests. Extensive simulations are conducted and the results have demonstrated the superior performance of our method.     

Handoff performance in wireless DS‐CDMA networks

This paper analyses the performance of DS‐CDMA networks in the presence of call handoffs. We show that a handoff may violate the SINR requirements for other users, and thus cause an outage in the target cell. We propose to use the probability of such events as a possible metric for quality of service in networks with multiple traffic types, and derive the corresponding QoS parameters. A two‐level admission policy is defined: in tier 1 policy, the network capacity is calculated on the basis of the bound on outage probability. However, this policy does not suffice to prevent outage events upon handoffs for various traffic types, and henceforth, we propose an extension that reserves extra bandwidth for handoff calls, thus ensuring that handoff calls will not violate the outage probability bound. The overhead imposed by the extension is negligible, as the complete two‐tier admission control algorithm is executed only when a call is admitted into the network. Once admitted, calls can freely execute handoffs using the reserved bandwidth. The modified second‐tier bandwidth reservation policy is adaptive with respect to the traffic intensity and user's mobility and we show that it can provide satisfactory call (flow) quality during its lifetime. Analytical results for the QoS have been verified by the simulations. Copyright © 2002 John Wiley & Sons, Ltd.     

Call admission control in mobile cellular networks: a comprehensive survey

Call admission control (CAC) is a key element in the provision of guaranteed quality of service (QoS) in wireless networks. The design of CAC algorithms for mobile cellular networks is especially challenging given the limited and highly variable resources, and the mobility of users encountered in such networks. This article provides a survey of admission control schemes for cellular networks and the research in this area. Our goal is to provide a broad classification and thorough discussion of existing CAC schemes. We classify these schemes based on factors such as deterministic/stochastic guarantees, distributed/local control and adaptivity to traffic conditions. In addition to this, we present some modeling and analysis basics to help in better understanding the performance and efficiency of admission control schemes in cellular networks. We describe several admission control schemes and compare them in terms of performance and complexity. Handoff prioritization is the common characteristic of these schemes. We survey different approaches proposed for achieving handoff prioritization with a focus on reservation schemes. Moreover, optimal and near‐optimal reservation schemes are presented and discussed. Also, we overview other important schemes such as those designed for multi‐service networks and hierarchical systems as well as complete knowledge schemes and those using pricing for CAC. Finally, the paper concludes on the state of current research and points out some of the key issues that need to be addressed in the context of CAC for future cellular networks. Copyright © 2005 John Wiley & Sons, Ltd.     

Call admission control for non‐geostationary orbit satellite networks and other capacity‐varying networks

Many networks, such as non‐geostationary orbit satellite (NGOS) networks and networks providing multi‐priority service using advance reservations, have capacities which vary over time for some or all types of calls carried on these networks. For connection‐oriented networks, call admission control (CAC) policies which only use current capacity information may lead to excessive and intolerable dropping of admitted calls whenever the network capacity decreases. Thus novel CAC policies are required for these networks. We present the admission limit curve (ALC) and prove it is a constraint limiting the conditions under which any causal CAC policy may admit calls and still meet call dropping guarantees on an individual call basis. The ALC also leads to a lower bound on the call blocking performance achievable by any causal CAC policy which provides dropping guarantees to individual calls. Also, we introduce a new CAC policy which uses knowledge of future capacity changes to provide dropping guarantees on an individual call basis and which achieves blocking performance close to the lower bound. Copyright © 2000 John Wiley & Sons, Ltd.     

无线移动通信系统中的呼叫接入控制

呼叫接入控制是无线移动通信系统中无线资源管理的重要部分,它直接关系到系统中用户服务质量是否能够得到保证,同时呼叫接入控制算法的有效性决定了系统资源的利用效率。文中综述了各种呼叫接入控制算法及其特点,并指出在无线移动通信系统中它们的重要性。     

Call admission control scheme for real-time services in packet-switched OFDM wireless networks

A call admission control scheme is proposed for real-time services in packet-switched orthogonal frequency division multiplexing （OFDM） wireless cellular networks. The main idea of the proposed scheme is to use maximum acceptance ratio to maintain maximum channel utilization for real-time services according to the desired packet-level and call- level quality-of-service （QoS） requirements. The acceptance ratio is periodically adjusted by using a time discrete Markov chain and Wiener prediction theory according to the varying traffic load. Extensive simulation results show that this algorithm maintains high channel utilization, even as it guarantees packet-level and call-level QoS requirements for real-time services.     

Call admission control scheme with normalized quality of service metric in IEEE 802.16 networks

IEEE 802.16 network introduces a multimedia data scheduling service with different quality of service (QoS) requirements. The scheduling service manages transmission resources according to data types, satisfying the requirements of different connections or users. On the basis of the data types defined in the service, we discuss a normalized QoS metric for the multimedia connections in the paper. The QoS value of a connection can be determined just by three components: the data type of the connection, its desired resources, and its allocated resources. Then, we propose an optimum bandwidth allocation solution, which can maximize the utility of base station. Next, we propose a call admission control scheme utilizing the bandwidth allocation solution. In the scheme, the occupied resource of ongoing connections will be regulated for the entry admission of a new connection, without degrading the network performance and the QoS of ongoing connections. Finally, the simulation results confirm that the proposed scheme with the normalized QoS can achieve better trade‐off between ongoing connections and new connections.Copyright © 2012 John Wiley & Sons, Ltd.     

无线/移动网络中自适应的接纳控制算法及性能分析

无线／移动网络中重要的连接级QoS性能指标包括新连接请求阻塞率(CBP)、切换连接请求丢弃率(HDP)等。其中，更不希望因切换连接请求的丢弃而导致服务的终止。为降低HDP，通常采用资源预留方案。但这种方案导致CBP较高、资源利用率低。本文针对自适应的多媒体应用带宽可以动态调整的特点，研究无线／移动网络中多优先级服务自适应的接纳控制机制，提出一个自适应的接纳控制算法，对其QoS性能进行分析。     

Adaptive admission/congestion control policies for CDMA‐based wireless internet

Radio resource management (RRM) is vital for the next generation wireless networks. RRM comprises many functionalities and this paper focuses on the investigation of the performance of several adaptive call admission/congestion control policies based on a window‐measurement estimation of the status of the buffer at the base station under the hybrid TDMA/CDMA access scheme. In our study, we interrelate the physical limitations of the base stations (i.e. the number of transmission and reception modems), call and burst level traffic, instantaneous buffer conditions and end‐to‐end bit error performance in one queuing problem. Subsequently, a window‐measurement estimator is implemented to estimate the likelihood of buffer congestion at the base station. Accordingly, the traffic loads shall be controlled. We use event‐driven simulation to simulate the multimedia integrated CDMA networks where heterogeneous traffic users are multiplexed into a simple TDMA frames. The simulation results show outstanding performance of the proposed call admission/congestion control policies in guaranteeing QoS requirements. Copyright © 2005 John Wiley & Sons, Ltd.     

Tiered bandwidth reservation scheme for multimedia wireless networks

It is important to provide quality of service (QoS) guarantees if we want to support multimedia applications over wireless networks. In this paper, considering the features of tiering in sectored cellular networks, we propose a novel scheme for bandwidth reservation to approach QoS provisioning. By predicting the movement of each connection, the reserving of bandwidth is only required in needful neighboring cells instead of in all neighboring cells. In addition, an admission control mechanism incorporated with bandwidth borrowing assists in distributing scarce wireless bandwidth in more adaptive way. Through mathematical analysis, we proof the advantages of tier‐based approach and the bound for the selection of tiered boundary. The simulation results also verify that our scheme can achieve superior performance than traditional schemes regarding no bandwidth reserving, fixed bandwidth reserving, and bandwidth borrowing in sectored cellular networks when performance metrics are measured in terms of the connection dropping probability (CDP), connection blocking probability (CBP), and bandwidth utilization (BU). Copyright © 2008 John Wiley & Sons, Ltd.