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1.
基于预留信道和强占优先相结合的接入策略   总被引:3,自引:1,他引:2  
李波  吴成柯  李冬 《通信学报》2000,21(3):12-18
报道了一种用于话音/数据综合的蜂窝移动通信系统中的基于预留切换信道和强占优先策略相结合的业务接入方案。在本方案中为具有越区切换请求的话音呼叫提供了预留切换信道和强占数据业务的优先权相结合的接入策略。同时为了提高系统总的承载话音的业务量,也为新近产生的话音呼叫提供了一定的强占数据业务的优先权。结果表明:我们的方案可以为移动用户提供更好的服务质量。  相似文献   

2.
增强对数据业务等非话音业务的支持,是LEO(低地球轨道)卫星通信系统的一个重要发展方向。提出了LEO卫星通信系统中一种新的保护信道和强占优先相结合的信道分配策略,即为话音呼叫提供一定的强占数据业务的优先权。将该策略与单纯保护信道策略的各项主要性能指标进行比较,结果表明新策略以略微增加数据时延为代价换取了话音新呼叫阻塞概率和切换阻塞概率的极大改善。  相似文献   

3.
3G动态预留呼叫接纳控制算法研究   总被引:3,自引:2,他引:1  
第三代移动通信技术支持不同服务质量(QoS)的多媒体业务,而呼叫接纳控制(CAC)技术是移动通信中的关键技术之一.本文提出一种动态预留呼叫接纳控制算法,该算法根据小区中各业务的话务量预测各业务所需信道教,从而为切换业务和新业务预留一定的信道.通过比较动态预留算法与新呼叫受限算法和中断优先级算法的性能,得出动态预留算法在降低语音和数据业务的呼叫阻塞率、中断率方面有明显的改善,是一种比较理想的呼叫接纳控制算法.  相似文献   

4.
基于排队理论的信道分配算法研究   总被引:1,自引:0,他引:1  
针对蜂窝移动通信系统,基于排队理论提出了一种信道分配方案。该方案将信道分为2部分:语音信道和数据保护信道。预留数据保护信道用于补偿数据丢包率,同时对语音业务设置FIFO排队缓冲器,切换呼叫优先占用缓冲器以确保切换优先。当语音信道空闲时,数据业务可以占用语音信道,一旦有语音呼叫请求到来且无可用语音信道,数据业务应释放占用的语音信道,在数据缓存器中排队等待。仿真结果表明该方案不仅降低了新增呼叫阻塞率和切换掉话率,而且提升了数据业务的性能。  相似文献   

5.
在3G(第3代移动通信系统)中,为了给不同类型的业务提供不同级别的端到端QoS,网络资源必须进行合理分配。QoS和资源分配是密不可分的,而无线资源分配显得尤为重要。文中提出了UMTS的QoS结构,分3部分对空中接口部分的QoS(即无线资源分配策略问题)进行了讨论:首先提出了一种RRA算法,接着讨论了W-CDMA和TD-CDMA系统的无线资源分配问题,最后讨论了下行链路及上行链路的呼叫允许控制(CAC)。  相似文献   

6.
本文提出了一种新的数学模型(GCS模型),该模型不同于以往多业务移动通信系统中模型,它不仅给切换话音业务预留了信道,而且还给切换数据业务预留了信道。  相似文献   

7.
未来的TD/CDMA移动通信系统中存活话音及上下行业务量不等、优先级不同的数据业务,为适应新业务的特点,充分发挥TDD/CDMA移动通信系统自身的优势,本文提出了TDD/CDMA移动通信的一种新的信道分配方案。仿真结果表明,该方案可大大降低低优先级业务的掉线概率,充分利用有限的信道资源。  相似文献   

8.
金山  洪海丽  倪淑燕 《电讯技术》2016,56(4):394-400
受平台准静止状态的影响,高空平台( HAPS)通信网络内存在大量的切换呼叫,且业务量动态变化。 HAPS网络可传输多种业务,其中实时业务在切换过程中具有较高的时延要求。通过为切换呼叫预留信道可降低平台不稳定对服务质量( QoS)造成的影响。在基于服务优先级的多业务信道分配算法基础上,重点对实时业务的信道分配算法进行改进,提出了一种基于概率的预留信道借用策略。该算法可根据网络内业务量的实时统计数据控制新呼叫业务的准入。仿真结果表明:与固定预留信道算法和门限预留信道算法相比,该算法能够适应网络内业务量的动态变化,在保证切换呼叫掉线率满足期望值的条件下提升系统的整体性能,降低平台不稳定造成的性能损失。  相似文献   

9.
基于第三代(3G)移动通信系统的时分同步码分多址(TD-SCDMA)集群通信系统,可以承载不同类型的集群业务,并能够为用户提供服务质量(QoS)保证。在无线网中提供QoS保证,呼叫接纳控制(CAC)扮演着重要的角色。在学习总结常规移动通信系统CAC方面研究成果的基础上,结合集群通信的特点,给出了适用于TD-SCDMA集群通信系统的呼叫接纳控制流程。  相似文献   

10.
多业务LEO卫星网络中最优呼叫允许控制及切换管理策略   总被引:2,自引:0,他引:2  
该文针对多业务条件下的LEO(Low-Earth-Orbit)卫星网络,提出了一种新的基于最优多门限信道预留(OMTCR)的呼叫允许控制(CAC)及切换管理策略,建立了评价LEO卫星网络连接级QoS性能的理论分析模型框架。借鉴经济学“收益函数”的概念分别建立了无QoS约束和有QoS约束的系统收益目标优化模型,求解在给定系统参数和输入业务条件下OMTCR的最优门限参数矢量。仿真结果表明OMTCR能够在不同用户QoS要求和系统收益目标的多业务环境下获得比传统CS(Completely Sharing)策略及GC(Guard Channel)策略更好的性能。  相似文献   

11.
In wireless cellular communication systems, call admission control (CAC) is to ensure satisfactory services for mobile users and maximize the utilization of the limited radio spectrum. In this paper, we propose a new CAC scheme for a code division multiple access (CDMA) wireless cellular network supporting heterogeneous self-similar data traffic. In addition to ensuring transmission accuracy at the bit level, the CAC scheme guarantees service requirements at both the call level and the packet level. The grade of service (GoS) at the call level and the quality of service (QoS) at the packet level are evaluated using the handoff call dropping probability and the packet transmission delay, respectively. The effective bandwidth approach for data traffic is applied to guarantee QoS requirements. Handoff probability and cell overload probability are derived via the traffic aggregation method. The two probabilities are used to determine the handoff call dropping probability, and the GoS requirement can be guaranteed on a per call basis. Numerical analysis and computer simulation results demonstrate that the proposed CAC scheme can meet both QoS and GoS requirements and achieve efficient resource utilization.  相似文献   

12.
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  相似文献   

13.
The call admission control (CAC) belongs to the category of resource management. Since the radio spectrum is very scarce resource, CAC is one of the most important engineering issues for mobile communications. In this paper, we propose a CAC scheme for direct sequence code-division multiple-access cellular systems supporting mobile multimedia communications services. There are multiple call classes in multimedia services and the required signal-to-interference ratio (SIR) varies with call classes. Call admission decision in the proposed scheme is based on SIR measurement. We take account of the traffic asymmetry between uplink and downlink, which is the most important characteristic of multimedia traffic. In addition, the proposed scheme guarantees the priority of handoff call requests over new call requests. We evaluate the performance of the proposed scheme using Markov analysis. The performance measures which we focus on are the system throughput and the blocking probabilities of handoff calls and new calls. The outage probability of a call in progress is also calculated, which is the probability that the measured bit energy-to-noise density ratio of the call is smaller than the required value for maintaining adequate transmission quality. We present some numerical examples with practically meaningful parameter values and, as a result, show that the proposed CAC scheme can operate well in the mobile multimedia systems such as the International Mobile Telecommunications-2000 (IMT-2000) systems.  相似文献   

14.
A traffic management scheme is proposed in a multicode code-division multiple-access system supporting soft handoff that uses guard channels and a queue for real-time traffic. Preemptive queue control gives priority to queued handoff calls. Handoff traffic is derived as a function of the new call arrival rate, the size of the soft handoff region, mobile speed, the new call blocking probability, and the handoff failure probability. System performance with K types of calls is analyzed by introducing a concept of effective channel. The effects of the number of guard channels, the number of effective channels, system capacity, and other factors are numerically investigated. The effectiveness of the proposed queue control scheme is also observed in terms of handoff processing delay  相似文献   

15.
The CAC (call admission control), which can guarantee call services to meet their QoS (Quality of Service) requirements, plays a significant role in providing QoS in wireless mobile networks. In this paper, an adaptive multiguard channel scheme‐based CAC strategy is proposed to prioritize traffic types and handoff calls. The major aim of the study is to develop the analytical model of the priority traffic and handoff calls based adaptive multiguard channel scheme and examining the performance through setting the value of the adaptive ratio parameters. Our proposed scheme tries to mediate the advantages and drawbacks of the static and dynamic CAC schemes. The proposed scheme is quite different from previous studies because multithreshold values have been considered for multiclass traffic by adaption parameters, and a closed form analytical model is developed The numerical results show that this scheme can be used to keep the targeted QoS requirement by suitably setting the adaptive ratio parameters. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

16.
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   

17.
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.  相似文献   

18.
In future personal communications networks (PCNs) supporting network-wide handoffs, new and handoff requests will compete for connection resources in both the mobile and backbone networks. Forced call terminations due to handoff call blocking are generally more objectionable than new call blocking. The previously proposed guard channel scheme for radio channel allocation in cellular networks reduces handoff call blocking probability substantially at the expense of slight increases in new call blocking probability by giving resource access priority to handoff calls over new calls in call admission control. While the effectiveness of a fixed number of guard channels has been demonstrated under stationary traffic conditions, with nonstationary call arrival rates in a practical system, the achieved handoff call blocking probability may deviate significantly from the desired objective. We propose a novel dynamic guard channel scheme which adapts the number of guard channels in each cell according to the current estimate of the handoff call arrival rate derived from the current number of ongoing calls in neighboring cells and the mobility pattern, so as to keep the handoff call blocking probability close to the targeted objective while constraining the new call blocking probability to be below a given level. The proposed scheme is applicable to channel allocation over cellular mobile networks, and is extended to bandwidth allocation over the backbone network to enable a unified approach to prioritized call admission control over the ATM-based PCN  相似文献   

19.
The call admission control (CAC) for mobile communications is one of the most important engineering issues since it belongs to the category of resource management and the radio spectrum is a very scarce resource. In future mobile cellular systems, the CAC scheme should be efficient for multimedia services as well as for voice services. This paper proposes an advanced CAC scheme for mobile multimedia communications. A characteristic of the proposed scheme is that it takes account of the traffic (load) asymmetry between uplink and downlink in mobile multimedia environments, we evaluate the performance of the proposed scheme using Markov analysis. The performance measures on which we focus are the utilization of resources and the blocking probabilities of handoff calls and new calls. We present some numerical examples with practically meaningful parameter values. As a result, we show that the proposed CAC scheme can be a good choice for mobile multimedia systems such as the International Mobile Telecommunications-2000 systems  相似文献   

20.
A novel call admission control (CAC) scheme for an adaptive heterogeneous multimedia mobile network with multiple classes of calls is investigated here. Different classes of calls may have different bandwidth requirement, different request call holding time and different cell residence time. At any time, each cell of the network has the capability to provide service to at least a given number of calls for each class of calls. Upon the arrival (or completion or hand off) of a call, a bandwidth degrade (or upgrade) algorithm is applied. An arriving call to a cell, finding insufficient bandwidth available in this cell, may either be disconnected from the network or push another call out of the cell toward a neighboring cell with enough bandwidth. We first prove that the stationary distribution of the number of calls in the network has a product form and then show how to apply this result in deriving explicit expressions of handoff rates for each class of calls, in obtaining the disconnecting probabilities for each class of new and handoff calls, and in finding the grade of service of this mobile network  相似文献   

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