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The concept of adaptive admission control in cellular wireless networks ensures quality of service by reserving bandwidth for handoff calls. It is equally important in current second generation wireless systems as well as in the future IMT-2000 and UMTS systems. In order to ensure bounded call level QoS we propose to track the changes of the handoff call arrival rate and integrate this information in the admission algorithm. However, the handoff call arrival rate can vary when the new call arrival rate and/or user mobility vary. In our previous work we have analysed bandwidth reservation techniques needed to maintain a stable call level QoS when new call arrival rate is changing in a group, or groups, of wireless cells. This paper analyses bandwidth reservation techniques that are adaptive to the user mobility as well as to the changing new call arrival rate, and which can ensure stable call level QoS over a range of user mobilities. We also propose the technique to derive bandwidth reservation policy when the QoS characteristics over a range of user mobilities are given. 相似文献
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In this paper a dynamic channel reservation and call admission control scheme is proposed to provide QoS guarantees in a mobile wireless network using the concept of influence curve. The basic idea behind the proposed scheme is that a moving user, in addition to its requirements in the current cell, exerts some influence on the channel allocation in neighboring cells. Such an influence is related to the moving pattern of the users and is calculated statistically. Furthermore we developed a general analytical model to calculate the corresponding blocking probabilities for wireless networks with multiple platforms, which removes the commonly used assumption that new calls and handoff calls have same channel holding time. The numerical results demonstrate that our scheme outperforms traditional channel reservation schemes and can effectively adapt to the real time network conditions. 相似文献
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In this paper, we develop call admission control algorithms for SIR-based power-controlled DS-CDMA cellular networks. We consider networks that handle both voice and data services. When a new call (or a handoff call) arrives at a base station requesting for admission, our algorithms will calculate the desired power control setpoints for the new call and all existing calls. We will provide necessary and sufficient conditions under which the power control algorithm will have a feasible solution. These conditions are obtained through deriving the inverse of the matrix used in the calculation of power control setpoints. If there is no feasible solution to power control or if the desired power levels to be received at the base station for some calls are larger than the maximum allowable power limits, the admission request will be rejected. Otherwise, the admission request will be granted. When higher priority is desired for handoff calls, we will allow different thresholds (i.e., different maximum allowable power limits) for new calls and handoff calls. We will develop an adaptive algorithm that adjusts these thresholds in real-time as environment changes. The performance of our algorithms will be shown through computer simulation and compared with existing algorithms. 相似文献
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Distributed Contention-Aware Call Admission Control for IEEE 802.11 Multi-Radio Multi-Rate Multi-Channel Wireless Mesh Networks 总被引:3,自引:1,他引:2
In this paper, we focus on call admission control (CAC) in IEEE 802.11 multi-radio multi-rate multi-channel (MR2-MC) wireless mesh networks (WMNs). CAC is the key component of QoS routing protocols. The goal of CAC is to protect existing
flows from QoS violations and fully utilize available radio resource on channels. We propose a CAC mechanism, called Contention-Aware
Multi-channel Call Admission Control (CMC), for MR2-MC WMNs based on IEEE 802.11 DCF. CMC is fully distributed, relies on local information to estimate the residual bandwidth
of a path, and can be integrated into existing routing protocols for MR2-MC WMNs to provide QoS. We evaluate the performance of CMC via ns-2 simulations. The results show that CMC can precisely
predict the end-to-end residual bandwidths of paths, successfully protects existing flows from QoS violations, and fully utilizes
the bandwidths on channels. 相似文献
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Call admission control is one of the key elements to guarantee the handoff call dropping probability in cellular networks. Among numerous proposals in the literature, the distributed call admission control policy (DCAC) seems to be promising, due to its simplicity and adaptability to changing traffic. However, one crucial assumption used in DCAC is that the actually admitted new calls has to obey a Poisson process to enter the network after the call admission control. Given the dynamic and distributed nature of the control process, this can neither be validated nor be easily implemented. In this paper, we will first discuss a generalized DCAC which eliminates the above assumption and can be used in general environments. Then, a mobility-aware DCAC is introduced, which considers the difference of handoff support between low and high mobility calls in making the CAC decision in order to improve channel utilization. The performance of the modified DCAC scheme is investigated through simulation studies. 相似文献
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In wireless multimedia communication systems, call admission control (CAC) is critical for simultaneously achieving a high resource utilization efficiency and maintaining quality-of-service (QoS) to mobile users. User mobility, heterogeneous nature of multimedia traffic, and limited radio spectrum pose significant challenges to CAC. QoS provisioning to both new calls and handoff calls comes with a cost of low resource utilization. This paper proposes a CAC policy for a wireless communication system supporting integrated voice and dataservices. In particular, soft QoS (or relaxed target QoS) is incorporated in the CAC policy to make compromises among different objectives.Numerical results are presented to demonstrate that (a) in dealing with the dilemma between QoS satisfaction and high resource utilization, how the resource utilization efficiency can be increased by introducing soft QoS; and (b) in accommodating different types of traffic, how the QoS of low priority traffic can be improved by specifying soft QoS to high priority traffic. 相似文献
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Wireless networks that utilize dynamic channel allocation (DCA) are known to perform better than those with fixed channel allocation, in terms of the call level QoS measures such as the handoff dropping probability. On account of this, the DCA networks are usually designed without the call admission control (CAC). However, given the decrease of cell sizes, together with ever increasing mobile phone and terminal population, dynamic channel allocation policies (such as channel borrowing) may not be sufficient to cope with the hot-spot area size and its traffic intensity. This paper analyses the performance of the DCA networks, both with and without the call admission control, under the hot-spot traffic regime. In such cases, the pure DCA approach fails to ensure sufficiently low level of QoS in both the hot-spot area and the surrounding cells. We propose a CAC policy that can stabilize the QoS under non-uniform traffic, whilst being easy to integrate in the distributed DCA policies. 相似文献
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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. 相似文献
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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. 相似文献
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Krishnamachari Bhaskar Gau Rung-Hung Wicker Stephen B. Haas Zygmunt J. 《Wireless Networks》2004,10(2):121-131
In a high-capacity cellular network with limited spectral resources, it is desirable to minimize the radio bandwidth costs associated with paging when locating mobile users. Sequential paging, in which cells in the coverage area are partitioned into groups and paged in a non-increasing order of user location probabilities, permits a reduction in the average radio costs of paging at the expense of greater delay in locating the users. We present a polynomial time algorithm for minimizing paging cost under the average delay constraint, a problem that has previously been considered intractable. We show the conditions under which cluster paging, a simple heuristic technique proposed for use with dynamic location update schemes, is optimal. We also present analytical results on the average delay and paging cost obtained with sequential paging, including tight bounds. 相似文献
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Fahad S. Al-Khaled 《International Journal of Communication Systems》1998,11(5):327-335
The radio channel assignment problem (CAP) is classified as an NP-complete binary optimization problem, which creates the need for faster, yet optimal optimization algorithms to reduce the time of computation when solving such a complex problem. Simulated annealing (SA), a powerful optimal combinatorial search algorithm, was found to be very suitable for CAP. This paper extends the standard capabilities of SA and proposes a new CAP-oriented, quicker binary SA, the binary dynamic SA (BDSA) algorithm, as part of a newly proposed radio channel assignment approach. Simulation results proved that the proposed BDSA has very fast convergence as a stand-alone algorithm and even faster convergence with the newly proposed radio channel assignment approach. © 1998 John Wiley & Sons, Ltd. 相似文献
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Franco Davoli Piergiulio Maryni Carlo Nobile 《International Journal of Wireless Information Networks》1996,3(4):235-242
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. 相似文献
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Yu Cheng Wei Song Weihua Zhuang Alberto Leon-Garcia Rose Qingyang Hu 《Mobile Networks and Applications》2006,11(5):661-679
This paper proposes efficient resource allocation techniques for a policy-based wireless/wireline interworking architecture,
where quality of service (QoS) provisioning and resource allocation is driven by the service level agreement (SLA). For end-to-end
IP QoS delivery, each wireless access domain can independently choose its internal resource management policies to guarantee
the customer access SLA (CASLA), while the border-crossing traffic is served by a core network following policy rules to meet
the transit domain SLA (TRSLA). Particularly, we propose an engineered priority resource sharing scheme for a voice/data integrated
wireless domain, where the policy rules allow cellular-only access or cellular/WLAN interworked access. By such a resource
sharing scheme, the CASLA for each service class is met with efficient resource utilization, and the interdomain TRSLA bandwidth
requirement can be easily determined. In the transit domain, the traffic load fluctuation from upstream access domains is
tackled by an inter-TRSLA resource sharing technique, where the spare capacity from underloaded TRSLAs can be exploited by
the overloaded TRSLAs to improve resource utilization. Advantages of the inter-SLA resource sharing technique are that the
core network service provider can freely design the policy rules that define underload and overload status, determine the
bandwidth reservation, and distribute the spare resources among bandwidth borrowers, while all the policies are supported
by a common set of resource allocation techniques. 相似文献
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This paper presents a new approach to prediction of resource demand for future handoff calls in multimedia wireless IP networks. Our approach is based on application of multi‐input‐multi‐output (MIMO) multiplicative autoregressive‐integrated‐moving average (ARIMA) (p,d,q)x(P,D,Q)S models fitted to the traffic data measured in the considered cell itself and on the new call admission control (CAC) algorithm that simultaneously maximizes the system throughput while keeping the handoff call dropping probability (CDP) below the targeted value. The main advantages of the proposed approach are the following: first, the proposed multi‐variable prediction method gives on average better predictions (i.e. narrower prediction confidence interval) for realistic traffic situations, which results in lower new call blocking probability (CBP) at the targeted handoff CDP and second, the model is simple to implement since it does not require communication among the adjacent cells. Simulation results show the superiority of the proposed MIMO prediction approach combined with the proposed call admission control algorithm for some typical nonstationary situations in comparison with univariate models. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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无线资源管理中的呼叫允许控制是TD-SCDMA的重要组成部分,性能优良的呼叫允许控制策略可以尽可能高地提高网络资源利用率。对于单纯的CDMA系统,呼叫允许控制必须依据目标信干比保证所有激活用户的服务质量.然而,TD-SCDMA系统的呼叫允许控制与其时隙分配方法有密切的关系,考虑了两种呼叫允许控制方案并给出仿真结果。 相似文献