影响无线系统间切换成功率的关键因素分析

文章分析了无线系统间切换的基本步骤和影响切换成功率的各项因素,认为影响切换成功率的关键因素是无线网络规划。为了提高无线系统间的切换成功率,网络运营者尤其应关注源侧的无线网络规划。     

WCDMA系统的容量规划

WCDMA系统的网络规划包括核心网规划和无线网络规划两大方面，而无线网络规划又可分为WCDMA无线资源规划、切换规划、或控规划、容量规划、覆盖规划等众多方面，本仅针对WCDMA系统的容量规划做一剖析。同时提出了增加WCDMA系统容量的具体方法。     

WCDMA下行链路软切换增益分析

在WCDMA无线网络中，由于新业务的非对称性，下行链路更有可能成为系统容量的瓶颈。研究了在理想功率控制下路径损耗因子、阴影标准方差等不同无线参数对下行链路软切换容量增益的影响，为无线网络规划提供了一定的依据。     

软切换对CDMA无线子系统的影响及控制

章介绍了CDMA系统无线资源的软切换的管理与控制，包括切换类型，切换策略，无线网络设计对网络的影响，切换参数的设置，搜索窗参数设置，邻小区参数设置以及无线网络优化等内容。     

GSM无线参数调整的探讨

无线网络参数对网络的服务性能有着重要的影响,合理调整无线参数是提高GSM网络整体性能的必要手段,基于上述理解,对影响SDCCH拥塞、TCH拥塞和切换成功率的相关参数的调整做了深入分析。     

CDMA 1X无线资源利用率与无线网络质量的关联分析

文章结合理论分析和实际数据,对无线资源利用率与Ec/Io覆盖率、无线掉话率、呼叫建立成功率、业务拥塞率等无线网络质量指标间的关系进行了分析,并讨论了在保障无线网络质量的前提下,如何把握无线资源利用率的变化时机进行系统扩容。     

CDMA1X无线资源利用率与无线网络质量的关联分析

文章结合理论分析和实际数据,对无线资源利用率与Ec/(I)o覆盖率、无线掉话率、呼叫建立成功率、业务拥塞率等无线网络质量指标间的关系进行了分析,并讨论了在保障无线网络质量的前提下,如何把握无线资源利用率的变化时机进行系统扩容.     

一种基于紧耦合网络结构的终端垂直切换系统

随着移动终端无线数据业务的迅速发展,在异构无线网络间提供无缝连接和高速的多媒体服务将成为下一代无线网络[1]（4G网络）的重要特性。提出了一套基于紧密耦合网络结构的终端垂直切换系统。该系统利用核心网络的PCF切换机制,有效解决了IP移动问题。被设计成客户端的一个软件接口,易于在现实世界中快速实施。     

地铁无线覆盖网络构架和关键技术研究

针对地铁无线网络覆盖中共建共享通信系统多、系统间干扰损耗大、覆盖场景多样性、小区间切换频繁等难点,提出含基站、电源、传输3个模块的地铁无线覆盖网络构架,同时对各种场景下无线网络覆盖策略、小区划分和切换策略,以及POI和泄漏电缆的应用等关键技术进行了深入的研究。将研究成果应用到某运营商地铁线路的网络建设中,达到了良好的覆盖效果。该研究为后期地铁无线网络设计提供了思路和建议。     

CDMA系统的网络优化

本文提出了衡量CDMA网络质量的主要指标，阐述了CDMA系统的网络优化流程，并对网络的覆盖与干扰、无线接通率、寻呼成功率、切换和掉话等问题的成因和定位方法进行了分析，最后提出一些常用的CDMA无线网络优化措施。     

Timely Effective Handover Mechanism in Heterogeneous Wireless Networks

Next-generation wireless networks should be able to coordinate and integrate different communication systems. It has been a challenging problem to support a seamless handover in these diverse wireless network environments. Link level triggers can provide information about events which can help handover decision and layer 3 entities better streamline their handover related activities. In most conventional layer 2 triggering approaches, a pre-defined threshold for a specific perspective such as the received signal strength is used. This may cause too late or too early handover executions. In this paper we propose a new predictive handover framework that uses the neighbor network information to generate timely the link triggers so that the required handover procedures can appropriately finish before the current link goes down. First we estimate a required handover time for the given neighbor network conditions, then using a predictive link triggering mechanism the handover start time is dynamically determined to minimize handover costs. The handover costs are analyzed in terms of the total required handover time and the service disruption time. The numerical analysis and simulation results show that the proposed method significantly enhances the handover performance in heterogeneous wireless networks.     

下一代无线通信网络中异构网络切换技术浅议

通过对无线通信网络的体系结构,运营方式,切换技术实现细节等方面的分析,研究和探讨异构网络之间的切换技术,最终提出一个面向下一代无线通信网络的新型的基于IP的综合切换(IH)框架,以实现全球无线网络覆盖范围的低时延、高带宽、宽切换域、开销低和QoS保证的不同网络间顺畅的无缝切换。     

一种基于femtocell群的缓存切换策略的研究

为了提高局部室内无线通信质量,家庭基站正逐步应用于各类室内无线通信场景。在密集部署femtocell场景中,当用户设备由宏小区层切换至femto层时,密集的femtocell信号会影响用户设备切换的准确性,增加用户设备切换开销和不必要切换概率。针对上述问题,在密集部署femtocell环境下针对切换提出一个femtocell分集理念,在提高切换准确性的同时,降低不必要切换次数,并在此基础上提出了一种缓存切换策略,以提高设备由宏小区层切换至femto层的效率,通过仿真对所提机制的性能进行了验证。     

Performance Analysis of a DS-CDMA Cellular System with Effects of Soft Handoff in Log-Normal Shadowing Channels

Next generation wireless communication is based on a global system of fixed and wireless mobile services thatare transportable across different network back-bones,network service providers and network geographical boundaries.This paper presents an approach to investigate the effects of soft handover and perfect power control on the forward link ina DS-CDMA cellular system.Especially,the relationships between the size ofhandover zone and the capacity gain are e-valuated under the log-normal shadow channel.Then the optimization of maximum forward capacity is very necessary tobe done with the maximum size of soft handover zone to the various system characteristics.     

网络切换对TCP吞吐量和公平性的影响分析

无线移动网络的发展日新月异.TCP协议是目前互联网上使用的最为广泛的端到端可靠传输协议,但其应用在无线网络上的时候,TCP性能下降明显.文中详细分析了TCP移动网络的切换对TCP造成影响的几个重要方面.最后通过在NS2上进行实验揭示了对多个TCP流公平性的影响,即切换后RTT越小的TCP流的吞吐量增长的越快,同时静态链路会夺取无线链路的链路资源.     

A Proactive Fuzzy-Guided Link Labeling Algorithm Based on MIH Framework in Heterogeneous Wireless Networks

Future wireless networks aim to provide a seamless connectivity among different communication networks, while offering a rich range of services with variable bandwidth and quality of service anytime and anywhere. Media independent handover (MIH) represents a successful deployment method towards the integration between heterogeneous wireless networks. It can provide the information about the parameters that affect on the events generation. An efficient system that generates links trigger mechanism will extensively impact the handover performance. This paper proposes a proactive fuzzy-guided algorithm with dynamic links triggering for vertical handover initiation based on the neighbor network information from the information server of MIH. The result shows that the proposed solution can avoid unnecessary handover and service interruption in the heterogeneous wireless network.     

基于区域感知贝叶斯决策的5G超密集异构网络联合垂直切换技术研究

针对无线通信异构网络切换中最优接入网的选择问题,现有研究主要集中于解决在两个网络间选择切换,而对于未来5G（5th Generation）通信系统中超密集网络的切换问题研究较少.本文就研究了5G无线通信系统中超密集异构网络的选择切换.文中提出了一种基于区域感知贝叶斯决策的联合垂直切换方式,该方案通过选择超密集异构接入网络的最优切换概率从而解决超密集网络切换问题.通过对移动用户（mobile station）从宏基站进入超密集服务小区,以及在小区内和小区间移动的不同场景进行仿真分析,研究结果表明本文决策方式能够准确地选择要切换的网络,因而该方案能够适用于超密集网络的应用场景.     

基于层次化网络编码的无线物联网协作切换机制

该文针对无线物联网中的多路径、多中继切换场景,提出了一种基于层次化网络编码(HNC)的协作切换机制。HNC机制在传统实用网络编码的基础上,利用中继节点距离网络接入点的跳数差异,引入了多层中继圈的思想,对网络进行分层。通过位于不同网络层次的中继节点的相互协作,建立移动终端与远程网络接入点之间的切换连接。HNC机制使移动终端在移动过程中可以保持可靠的切换连接。     

多网络共存下基于贝叶斯的垂直切换算法

针对目前的垂直切换技术普遍不能满足多网络下的切换问题,提出了一种改进的基于贝叶斯决策的垂直切换算法。首先根据接入终端网络的信号强度、网络负载、误码率和网络阻塞率以及用户业务对网络的实际需求偏好建立多条件相关的切换概率分布,计算出先验切换概率;然后通过贝叶斯决策算法计算出后验概率来进行判决比较,从而选取最优的接入网络。仿真结果表明,该算法不仅能有效地实现不同接入技术之间的垂直切换,从而减少不必要的切换,提高了切换成功的概率,而且还能在维持各网络平均负载达到30%~40%时减轻通信热点的阻塞情况,为用户提供更优的服务质量。     

Handover approaches for seamless mobility management in next generation wireless networks

Next generation wireless networks (NGWN) will be an integration of heterogeneous wireless access networks that will interwork over an IP‐based infrastructure. This all‐IP vision has led to the development of handover mechanisms to support seamless mobility for active network services among the different interworking wireless networks in order to ensure network access ubiquity in NGWN. These handover mechanisms need to ensure that mobile devices continue to receive ongoing communication without any noticeable disruption during handover events among the heterogeneous networks. This paper gives a qualitative and quantitative review of current handover approaches of IP mobility management protocols for NGWN with an objective to introduce a new way of further optimizing the handover performance. In particular, the paper focuses on handover approaches of mobile IPv6 (MIPv6) based mobility management protocols. Thus, the need, benefits, and limitations of these handover approaches are explored. Thereafter, dynamic handover coordination is introduced as a new viable solution that exploits the benefits and mitigates the limitations of these handover approaches hence improving handover performance in terms of handover delay, packet loss, and signaling overhead. Copyright © 2011 John Wiley & Sons, Ltd.