HSDPA系统接纳控制策略性能研究

文中指出了在支持HSDPA接入技术的网络中,研究接纳控制的目的和意义,分析了基于吞吐量的接纳控制算法,着重研究了下行链路上基于功率的接纳控制算法,针对HSDPA系统的特点,分析和阐述了三种基于不同测量值的算法.在仿真中,就多种接纳门限的设定、数据业务QoS是否分级等对系统性能的影响问题进行了分析与说明.     

一种针对HSDPA中继系统的比例公平调度算法

由于系统在资源分配上的差异,现有的3GPP长期演进项目的后续演进(Long Term Evolution Advanced,LTE-A)中继系统中的调度算法并不能直接应用于高速下行链路分组接入(High Speed Downlink Packet Access,HSDPA)中继系统。提出了一种适合HSDPA中继系统的比例公平调度算法,并给出了算法流程。通过系统级仿真,比较了该算法与没有中继时的PF调度算法和两层比例公平(THPF)调度算法的性能。仿真结果表明,所提出的调度算法能够在提高用户吞吐率的同时更好地保证用户公平性要求。     

HSDPA系统中HS-SCCH的功率控制算法

为提高高速下行链路分组接入(HSDPA)系统功率的利用率,降低干扰,提出了HS-SCCH控制信道的两种功率控制算法:基于下行DPCCH导频域的功率偏移和基于CQI的功率控制.仿真表明,当信道条件好、时延小的时候,第一种算法优于第二种算法大约1～2 dB;当信道条件差、时延大的时候,第二种算法优于第一种算法大约2～5 dB.两种算法结合使用时,能达到更好的效果.     

HSDPA中的公共信道利用分析

传统集中模式下的高速下行链路分组接入(HSDPA)公共信道协商机制与宽带码分多址(WCDMA)、传统GSM网络无本质区别,游离于无线资源分析之外,成为信道设计的盲区。由于缺乏有效监控和调节反馈策略,不仅间接影响客户感知,也直接加剧频谱资紧张。为此,以个体局部纳什(Nash)均衡和整体萨谬尔森(Samuelson)均衡的公共信道共享策略比较为前提,考虑漫游用户信令传递过多依赖各专用信道,以及系统承载信令对公共信道的挤占效应两方面的正负影响。分析了3种各自不同优先级别情况下,漫游用户群和系统在HSDPA公共信道利用对整体效用的影响,最终初步建立了整体效用最大化的公共信道利用分析模型。     

后3G移动通信系统中的HSDPA技术

对基于由IS-95和GSM向3G及后3G系统的两种过渡方案作了简单比较，在此基础上重点讨论了高速下行分组接入(HSDPA)技术，并对其中的关键技术作了说明。     

WCDMA中HSDPA和HSUPA的技术比较分析

高速下行分组接入（HSDPA）和高速上行分组接入（HSUPA）分别是3G中R5和R6的技术特征，通过采用快速链路适配、基于Node B的调度、具有软合并的混合自动重传请求（HARQ）等关键技术，可让用户设备（uE）能以尽可能高的功率传输数据，在减少时延的基础上得到更高的系统吞吐量。文中通过比较两者的异同来讨论其技术原则及关键技术。     

移动高速数据包通信的模糊快速小区选择

在高速下行数据包接入(HSDPA)系统中,软切换会给下行链路带来严重干扰,降低链路容量.3GPP相关文档提出通过快速小区选择(FCS)来解决上述问题,其中用户设备(UE)以导频信号强度作为选择通信小区的唯一依据.为平衡小区间业务量,本文结合导频信号强度、小区呼叫到达率和基站可用功率,提出了模糊快速选择小区的算法(FFCS).分析和仿真结果表明采用FFCS技术能有效提高业务量相对繁重小区的容量.     

异构无线系统中一种改进的呼叫准入方案

针对异构无线系统中上、下行业务需求不平衡引起的拥塞现象,提出了一种改进的呼叫准入方案。首先给出接入倾向度的概念,在接入时考虑用户的实际接入需求,并进一步提出了基于接入倾向度的呼叫准入改进方案,最后利用无差别曲线的方法确定接入倾向度的选择。仿真结果表明,改进后的方案在系统性能与用户公平性之间做到了较好折衷,具有较大的实用价值。     

HSDPA网络组网方案研究

随着3G网络的蓬勃发展,传统的R99系统已不能满足日益庞大的数据业务需求,HSDPA作为一种高速下行分组接入的移动通信技术,比WCDMA的技术水平更高,可以在不改变运营商已建的WCDMA网络结构的情况下将WCDMA网络升级,把下行数据业务速率提高到10Mbit/s,适应了未来数据业务的发展方向。     

HSDPA技术中HARQ的一种新组合译码算法

文中介绍了HSDPA中组合译码的组合方案,并在传统Chase组合译码算法的基础上提出了一种改进的新组合译码算法。最后通过计算机仿真,结果表明采用新算法的HARQ在有效减少重传次数方面明显优于采用无组合译码算法的HARQ。     

A New Call Admission Control Scheme Based on Mobile Position Estimation in DS-CDMA Systems

Call dropping is considered more annoying than call blocking in wireless cellular networks. The cost of the classical method of employing guard channels to decrease the call dropping rate is the increase in call blocking rate. Since subscriber mobility changes in time, the number of handoff attempts in each cell is subject to fluctuations, making static assignments (or periodical update) of a given number of guard channels inefficient. In this paper, we propose an adaptive scheme that employs reservations, instead of static assignments, to adaptively adjust the number of guard channels in each cell according to the current requirements. Thus, unnecessary allocation of guard channels is avoided resulting in a lower cost in terms of call dropping. The reservation requests are made according to the recent mobility pattern of the subscriber. A likelihood value is associated with each reservation request so that fewer channels are reserved by benefiting from the statistical accumulation of the requests. The channels are reserved by considering the interference that would be created once they are in use. The proposed scheme is evaluated against the classical guard channel scheme with a realistic mobility model.This author is currently associated with Georgia Institute of Technology-Regional Engineering Program (GTREP).Tuna Tugcu received his B.S. and Ph.D. degrees in computer engineering from Bogazici University in 1993 and 2001, respectively, M.S. degree from New Jersey Institute of Technology in 1994. He pursued post-doctorate study in Broadband and Wireless Networking Lab at Georgia Institute of Technology until July 2002. Currently, he is a visiting assistant professor at Georgia Institute of Technology-Regional Engineering Program. His research interests include real-time systems, communication networks, and wireless communications. Dr. Tugcu is a member of the IEEE.Cem Ersoy received his B.S. and M.S. degrees in electrical engineering from Bogazici University in 1984 and 1986, respectively. He worked as an R&D engineer in NETAS A.S. between 1984 and 1986. He received his PhD in electrical engineering from Polytechnic University in 1992. Currently, he is a professor in the Computer Engineering Department of Bogazici University. His research interests include performance evaluation and topological design of communication networks, wireless communications and mobile applications. Dr. Ersoy is a Senior Member of the IEEE.     

一种改进的CDMA自适应呼叫接纳控制算法

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，有效的CAC算法能满足各类业务的不同OoS要求，还能提高资源利用率。文中讨论了一种改进的基于cDMA系统门限的自适应接纳控制算法，仿真结果表明改进后的算法与传统算法相比具有比较好的性能．     

TD-SCDMA系统呼叫允许控制分析

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。     

多业务CDMA系统快速自适应呼叫准入控制算法

为了保证干扰受限多业务CDMA移动通信系统工作稳定可靠,必须有效、快速、准确地控制接入系统中的各类业务的用户数目,这一任务由呼叫准入控制(CAC)算法来完成.本文提出的基于门限比较的快速自适应CAC (FACAC)算法与传统的同类算法相比,具有判决速度快、判决精度高、门限自适应和简单易行等特点.仿真结果验证了理论推导的正确性,表明FACAC算法的中断特性优于传统CAC算法60%以上,系统服务等级(GoS)优23%左右(系统业务负荷较高时).     

A Modified Distributed Call Admission Control Scheme and Its Performance

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.     

一种新的CDMA系统多业务接入控制算法

文中提出一种新的CDMA系统中多业务接入控制算法。为了提高系统容量,在传统容量干扰受限的CDMA系统接入控制算法的基础上,考虑各种业务的激活因子,计算出系统接入呼叫用户后各个业务的中断概率,根据其中断概率是否满足QoS要求判断业务是否接入。仿真结果表明：所提算法的各种业务的阻塞概率明显低于传统算法,并且系统获得的性能改善随着桌些业务呼叫强度的增加而下降,从而证明了所提算法在系统容量上的优势。     

ATM基于神经模糊算法的呼叫接入控制

本文研究 ＡＴＭ通信网络基于在线测量的呼叫允许接入控制问题。文章提出利用神经－模糊算法在线协调模糊规则中的参数，并在此基础上，实现了一种新的ＣＡＣ机制。在确保服务质量的情况下，提高网络资源利用率，通过实例仿真表明了应用此种算法的可行性。     

A Novel Effective Bandwidth Based Call Admission Control for Multimedia CDMA Systems

A novel Call Admission Control(CAC)scheme is proposed for multimedia CDMA systems.The effectivebandwidth of real time calls is reserved in the CAC with the consideration of active factors.The admission of non-real timecalls is controlled by the system according to the residual effective bandwidth left from real time calls.Simulation resultshave shown that the novel CAC has greatly enlarged the admission region for real time calls and make the transmission de-lay of non-real time calls under an acceptable level.     

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.     

TD-SCDMA集群通信系统中的呼叫接纳控制策略研究

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。