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。     

3G系统中的呼叫接纳控制概述

在简要介绍了无线资源管理和呼叫接纳控制概念的基础上,通过深入分析CDMA网络中的小区负荷及其测量方法,全面讨论了3G系统中的呼叫接纳控制算法设计问题。     

异构网络中联合会话接纳控制算法综述

异构网络中的联合会话接纳控制算法就是负责处理新来到的或是切换的会话呼叫请求,根据网络性能、业务类型或是用户偏好等策略,决定会话被哪个RAT（无线接入技术）所接纳。文章介绍了联合会话接纳控制的概念以及主要功能,重点总结了几种主流的联合会话接纳控制算法,并且简要分析了各种算法的优缺点。     

Ad Hoc网络中的呼叫接纳控制

首先概述了Ad hoc网络呼叫接纳控制的原理;其次详细分析和总结了目前应用在Ad hoc网络中的几种呼叫接纳控制方法,并在此基础上分析决定CAC的关键因素;最后对目前CAC算法进行总结.     

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     

CDMA系统中呼叫接纳控制算法研究

呼叫接纳控制（CAC）是CDMA蜂窝系统无线资源管理的重要功能实体，它建立在对各小区负荷的测量基础之上。有效的CAC算法能满足各类业务的不同QOS要求的同时，还能提高资源利用率。文中通过深入分析小区负荷并进行仿真，讨论了CDMA系统中的呼叫接纳控制算法的设计问题。     

神经计算技术在ATM光纤高速智能管理网中的应用(续)

4　呼叫管理级呼叫管理级的主要功能是呼叫连接接纳控制。呼叫连接接纳控制意味着 ,仅当网络节判断得知新的连接将不会降低已接入老用户要求的服务质量时 ,才能允许接纳一个新用户的连接。例如 ,当用户 USE1要求与另一个用户 USE2通话时 ,首先 USE1用户向ATM网络节呼叫级控制器发送一个建立连接请求的信号。表征此连接请求的参数将包括目的用户、请求连接的承诺信息速率 (Commited InformationRate)、要求的服务质量等级 (GOS)以及生成信元信息特征参数等。网络节控制器由传输信息量参数评价各连接的服务质量水平 ,仅当评价表明对其…     

用于无线视频传输的分级编码策略研究

研究一个运用分级编码进行点对点和点对多点无线视频传输的方案,该方案简化了呼叫接纳控制机制,采用区分处理、有条件重传等策略来提高无线视频传输的可靠性和有效性,最后给出一个采用分级编码的无线视频传输模型.     

CDMA系统小区负荷分析

目前3G标准(WCDMA、cdma2000、TD-SCDMA)都基于CDMA技术,CDMA系统是自干扰受限系统,系统容量为“软容量”,即不是固定值,取决于网络中的干扰,有较大弹性,网络覆盖范围和服务质量与同时接受的用户数量之间有平衡和折中的关系。如果空中接口负荷增加过度,小区的覆盖面积就会低于预计值,已有连接的服务质量也无法保证。因此合理有效的呼叫接纳控制(CAC,calladmissioncontrol)对3G系统的稳定运行具有重要意义。在3G系统中,呼叫接纳控制是无线资源管理(RRM)的重要功能实体,用于判断资源分配请求是否被系统接受,目的是维护网络稳定,保…     

软交换网络的路由设计

软交换(softswitch)体系结构是目前颇受推崇的面向网络融合的新一代多媒体业务整体解决方案，具有层次化、呼叫控制与承载分离、快速开发业务、集中部署业务等特点，可以向用户提供包含PSTN话音、无线话音、基础数据、多媒体数据等各种业务。通过优化网络结构，不但实现了网络的融合，更重     

QoS Provisioning in Wireless/Mobile Multimedia Networks Using an Adaptive Framework

Recently there is a growing interest in the adaptive multimedia networking where the bandwidth of an ongoing multimedia call can be dynamically adjusted. In the wireless/mobile multimedia networks using the adaptive framework, the existing QoS provisioning focused on the call blocking probability and the forced termination probability should be modified. We, therefore, redefine a QoS parameter – the cell overload probability – from the viewpoint of the adaptive multimedia networking. Then, we propose a distributed call admission control (CAC) algorithm that guarantees the upper bound of the cell overload probability. Also, a bandwidth adaptation algorithm which seeks to minimize the cell overload probability is also presented. Simulation experiments are carried out to verify the performance of the proposed CAC algorithm. Furthermore, the performance of the adaptive wireless/mobile network is compared to that of the existing non-adaptive wireless/mobile networks. As a further step in QoS provisioning, we propose another QoS parameter, the degradation period ratio, and discuss analytically how the CAC algorithm guarantees the upper bound of the degradation period ratio.     

Call admission control for mobile multimedia communications withtraffic asymmetry between uplink and downlink

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     

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。     

An FDD wideband CDMA MAC protocol with minimum-power allocation and GPS-scheduling for wireless wide area multimedia networks

A frequency division duplex (FDD) wideband code division multiple access (CDMA) medium access control (MAC) protocol is developed for wireless wide area multimedia networks. In order to reach the maximum system capacity and guarantee the heterogeneous bit error rates (BERs) of multimedia traffic, a minimum-power allocation algorithm is first derived, where both multicode (MC) and orthogonal variable spreading factor (OVSF) transmissions are assumed. Based on the minimum-power allocation algorithm, a multimedia wideband CDMA generalized processor sharing (GPS) scheduling scheme is proposed. It provides fair queueing to multimedia traffic with different QoS constraints. It also takes into account the limited number of code channels for each user and the variable system capacity due to interference experienced by users in a CDMA network. To control the admission of real-time connections, a connection admission control (CAC) scheme is proposed, in which the effective bandwidth admission region is derived based on the minimum-power allocation algorithm. With the proposed resource management algorithms, the MAC protocol significantly increases system throughput, guarantees BER, and improves QoS metrics of multimedia traffic.     

Optimal resource allocation and adaptive call admission control for voice/data integrated cellular networks

Resource allocation and call admission control (CAC) are key management functions in future cellular networks, in order to provide multimedia applications to mobiles users with quality of service (QoS) guarantees and efficient resource utilization. In this paper, we propose and analyze a priority based resource sharing scheme for voice/data integrated cellular networks. The unique features of the proposed scheme are that 1) the maximum resource utilization can be achieved, since all the leftover capacity after serving the high priority voice traffic can be utilized by the data traffic; 2) a Markovian model for the proposed scheme is established, which takes account of the complex interaction of voice and data traffic sharing the total resources; 3) optimal CAC parameters for both voice and data calls are determined, from the perspective of minimizing resource requirement and maximizing new call admission rate, respectively; 4) load adaption and bandwidth allocation adjustment policies are proposed for adaptive CAC to cope with traffic load variations in a wireless mobile environment. Numerical results demonstrate that the proposed CAC scheme is able to simultaneously provide satisfactory QoS to both voice and data users and maintain a relatively high resource utilization in a dynamic traffic load environment. The recent measurement-based modeling shows that the Internet data file size follows a lognormal distribution, instead of the exponential distribution used in our analysis. We use computer simulations to demonstrate that the impact of the lognormal distribution can be compensated for by conservatively applying the Markovian analysis results.     

The integration of ad hoc sensor and cellular networks for multi-class data transmission

This paper targets mobile telemedicine applications that can be supported using third generation (3G) cellular networks, to provide highly flexible medical services. On the other hand, large-scale Ad hoc Sensor Networks (ASN), when deployed among mobile patients who may carry different kinds of micro-sensors to measure ECG, blood pressure, basal temperature or other physiological data, can provide a dynamic data query architecture to allow the medical specialists to monitor patients at any place. So far very little research has been conducted to explore the possibility of integrating ASN with mobile telemedicine. In this paper: 1. we suggest an integrated architecture that takes advantage of the low cost mobile sensor networks and 3G cellular networks to support multimedia medical calls with differentiated Quality-of-Service (QoS) requirements. 2. We propose a low-energy, distributed, concentric-zone-based data query mechanism that has the advantages of both proactive and reactive ad hoc routing algorithms to collect medical results from large-scale mobile patients for medical specialists who use cellular network to report patient data to the medical center. 3. In order to minimize the ambulance wireless call-dropping rate, we adopt accurate resource reservation call admission control (CAC) scheme to allocate the necessary bandwidth in the destination cell. 4. In order to meet the QoS requirements of patients’ wireless calls, we use dynamic guard channel CAC scheme to keep their handoff-call dropping rate below a certain threshold. We evaluate the validity of our schemes through simulations and analyze their performance. Our results clearly indicate the efficiency of the proposed CAC and sensor network query algorithms to meet the multimedia telemedicine QoS requirements.     

Soft QoS in Call Admission Control for Wireless Personal Communications

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.     

Call admission control for CDMA mobile communications systems supporting multimedia services

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.     

3G动态预留呼叫接纳控制算法研究

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.