基于网络编码的无线物联网多中继协作切换机制

 本文针对网状结构的无线物联网中的多跳切换场景,提出了一种基于网络编码的多中继协作切换机制MRH.MRH机制中采用了基于势能场的路由探测算法,通过中继协作的方式,将移动终端同时注册到多个漫游域上.配合网络编码,MRH机制使移动终端建立了到多个无线物联网接入点之间的灵活、可靠的切换连接,实现了在多个无线物联网间的平滑切换.     

基于中继技术的LTE-A终端省电方案

利用LTE-A协议对中继技术的支持,提出将中继协议集成到移动终端内部,在充电状态下切换为中继节点,为附近其他移动终端提供信号中继服务,从而达到省电的目的。当附近多个移动终端切换为中继节点时,使用V-MIMO技术与基站连接以帮助其他移动终端提高信号质量和速率。     

利用智能天线实现多点中继功能的Ad Hoc网络MAC协议

在Ad Hoc网络中,采用多跳传输来提高数据传输的质量以及速率。传统的单中继节点已经不能适应迅速增大的数据量以及节点的移动造成的信道衰落情况,所以本文提出了基于智能天线实现多点中继的MAC协议,该协议采用了智能天线实现了菱形握手机制,使数据实现同步传输。其次采用空时编码的协作机制,通过估计源信号来防止中继节点与目的节点信道衰落的情况。最后利用Busy Tones解决了隐藏终端和暴露终端的问题。通过仿真与比较证明MRDMAC协议在数据延时和通过率等各个方面都有很大的优越性。     

WiFi终端漫游原理及实现

随着信息网络技术的高速发展,WIFI网络在日常工作和生活中的应用也越来越普及。无线接入点AP是WIFI网络接入的最基本单元,组建一个覆盖区域较大的WIFI网络时,我们完成多个AP接入点的部署。当WIFI终端在多个AP组建的WIFI网络中移动时,终端将根据WIFI信号的强弱来实现不同AP接入点之间的自动切换,我们将该自动切换的过程称为"漫游"。实现WIFI漫游,将有助于提高WIFI网络的体验效果,文章主要介绍WIFI漫游的原理及改善终端漫游行为的综合策略。     

无线Adhoc网络中一种基于网络编码的协同MAC协议

协同通信中,中继节点通常用来转发源节点的数据分组.但是从中继节点的角度出发,帮助其它节点转发数据会降低其自身的性能,导致中继低效率问题的出现.针对此问题,该文基于网络编码设计了一种适用于无线Ad hoc网络的协同MAC协议.该协议将网络编码和协同机制相结合,在需要协同传输时,利用网络编码让中继节点在发送源节点数据的同时也发送自身的数据,利用网络编码来解决协同传输中中继低效率问题,进一步提升协同传输的性能.该文还在2维Markov退避模型的基础上,加入了网络编码和协同机制,对所提协议在多跳网络中进行了吞吐量性能分析,并探讨了网络节点数、多跳和信道质量对吞吐量性能的影响.仿真结果表明,相比一般的协同MAC协议,采用网络编码的协同MAC协议可以显著的改善系统性能,是解决协同传输中的中继低效率问题的有效手段.     

多源多目的模型中网络编码的时延性能分析

研究表明基于无线信道的广播特性,网络编码技术能够显著降低多播通信中的传输时延。多源多播模型中,在任一源节点已知其他源节点信息的条件下,现有传输方案能够确保系统时延最小化。本文在其他源节点信息未知时,对现有多源多目的单中继模型应用网络编码后的时延性能进行分析,并将该模型推广到多中继模型,提出了基于网络编码和机会中继选择策略的MR-OPP-NC方案,并在译码转发机制下,利用中断概率量化了应用网络编码前后的时延性能,仿真表明本文所提MR-OPP-NC方案与未使用网络编码的机会中继方案相比较,能获得显著的时延增益。      

一种基于移动IPv6协议的软切换实现方案

移动IPv6协议解决了IPv6网络中移动节点的位置更新和路由可达问题,使移动节点能够在不同IPv6子网间进行切换而不中断当前连接。但是这种切换的时延较长,影响移动IPv6网络的性能。为了减少切换时延,文章在移动IPv6协议中引入软切换技术,提出一种采用绑定更新计时器和路由优先级变换机制的软切换工程实现方案,实验结果表明,该软切换方案可以有效提高移动IPv6网络的性能。     

基于网络编码的无线网络分布式协作通信机制

 本文提出了一种基于无线网络编码的协作通信机制NCCC.无线网络编码能够在取得合作分集的性能增益的同时,降低网络中断概率.分布式中继节点选择算法是NCCC机制的核心,该算法根据即时信道状态,选择执行网络编码操作的最优中继节点.理论和仿真结果证明, NCCC机制可以提高无线网络双向多信源多信宿传输的性能和鲁棒性.     

基于灰预测模型的蓝牙网络切换算法

蓝牙网络接入点切换问题是构建蓝牙网络必须考虑的关键问题,而蓝牙特点给接入点切换的实现带来了极大挑战。提出了一种基于灰预测模型的蓝牙网络切换算法,该算法对链路质量信息的数量和分布特征没有苛刻要求,仅用少量样本数据就可以预测出下一时间链路质量,当预测值低于阈值时,接入点搜索网络拓扑结构找出最佳接入点集合,并实时监测切换终端与集合中接入点之间链路质量,预测出下一时刻链路质量,当切换终端链路质量预测值低于另一阈值时,接入点选择最佳接入集合中预测值最佳的接入点完成切换。该算法预测过程可以动态地调整参数,实现自适应预测,提高了预测的精度。仿真结果表明,使用该算法减少了终端切换时延以及误切换概率。     

嵌套移动网络路由优化代价分析模型的创建

在现代社会中,人们通信过程中的设备与无线传感器种类也越来越丰富,对于获得信息的需求也在逐渐改变,互联网连接模式中的固定终端与单一化移动终端已经无法使实际需求得到满足,在关联设备群中进行移动。此多个无线终端设备共同移动,会使互联网接入点改变,创建稳定移动体,也就是网络移动性。为了解决嵌套移动网络中的路由优化与数据包多层封装的问题,提出嵌套移动网络路由优化分析模型。     

基于重叠网络的移动IPv6快速切换

基本的移动IPv6切换延迟太大，不能满足实时业务的要求。本文提出了一种基于重叠网络的移动IPv6快速切换算法，这种算法通过在两个不同的IPv6子网间设置重叠网络来实现IP层的无缝(零延迟)切换。文中给出了算法实现的网络结构及其切换过程，并且对其性能进行了分析。算法实现了移动IPv6快速切换，在大部分情况下都可以达到最佳性能。     

Mobility management incorporating fuzzy logic for heterogeneous aIP environment

The next generation in mobility management will enable different mobile networks to interoperate with each other to ensure terminal and personal mobility and global portability of network services. However, in order to ensure global mobility, the deployment and integration of both satellite and terrestrial components are necessary. This article is focused on issues related to mobility management in a future mobile communications system, in a scenario where a multisegment access network is integrated into an IP core network by exploiting the principles of Mobile IP. In particular, attention is given to the requirements for location, address, and handover management. In a heterogeneous environment, the need to perform handover between access networks imposes particular constraints on the type of information available to the terminal and network. In this case, consideration will need to be given to parameters other than radio characteristics, such as achievable quality of service and user preference. This article proposes a new approach to handover management by applying the fuzzy logic concept to a heterogeneous environment. The article concludes with a presentation of mobility management signaling protocols     

Evaluation of handover mechanisms in shadowed low earth orbit land mobile satellite systems

This paper presents a quantitative analysis by computer simulation of the active set update (ASU) handover algorithm for a shadowed low earth orbit (LEO) land mobile satellite (LMS) environment. As a precursor to the handover analysis, the mutual visibility statistics for a 66 satellite polar and 48 satellite rosette-type constellation are presented. These results show the statistical nature of the levels of satellite diversity and mobile-to-satellite elevation angles (to the highest satellite) within each network and also indicate the influence of the channel characteristics on the handover strategy. A two-state Markov modulated channel model is assumed in the handover analysis, and this enables the assessment of increased levels of power and time hysteresis on the quality of service and network signalling load in a shadowed land mobile satellite environment. In particular, attention is given to the different modes of ASU operation for hard handover, switch diversity and soft handover.     

An improved handover algorithm based on signal strength plus distance for interoperability in mobile cellular networks

In future generation mobile cellular systems, position location of mobile terminal is expected to be available. In this paper, we propose an initiation algorithm for intersystem handover based on the combination of position location of mobile terminal and the absolute signal strength thresholds. Global System for Mobile communication (GSM) and Universal Mobile Telecommunication Systems (UMTS) networks are considered for interworking. The proposed algorithm reduces the handover rate by around 50% and thus improves the network resource efficiency as compared to that based on signal strength thresholds only.     

Analysis and Evaluation of Mobile IPv6 Handovers over Wireless LAN

In this paper, we analyze the IPv6 handover over wireless LANs. Mobile IPv6 is designed to manage mobile nodes movements between wireless IPv6 networks. Nevertheless, a mobile node cannot receive IP packets on its new point of attachment until the handover completes. Therefore, a number of extensions to Mobile IPv6 have been proposed to reduce the handover latency and the number of lost packets. We focus on Fast Mobile IPv6 which is an extension of Mobile IPv6 that allows the use of L2 triggers to anticipate the handover. We compare the handover latency in four specific cases: basic Mobile IPv6, the forwarding method of Mobile IPv6, the Anticipated method, and the Tunnel-Based Handover. The results of the handover latency are calculated with the L2 properties of IEEE 802.11b. In particular, we take into account the L2 handover for different configurations of the wireless network.     

A Traveling Distance Prediction Based Method to Minimize Unnecessary Handovers from Cellular Networks to WLANs

We propose a handover decision method based on the prediction of traveling distance within an IEEE 802.11 wireless local area network (WLAN) cell. The method uses two thresholds which are calculated by the mobile terminal (MT) as it enters the WLAN cell. The predicted traveling distance is compared against these thresholds to make a handover decision in order to minimize the probability of handover failures or unnecessary handovers from a cellular network to a WLAN. Our analysis shows that the proposed method successfully keeps the number of failed or unnecessary handovers low.     

移动IPv6切换时延优化新方法

移动IPv6中,移动节点(MN)在不同子网间移动时,既不中断与通信对端(CN)的通信,也不用改变其本身的IP地址.但是当MN与其家乡代理(HA)之间相距较远时,移动IPv6切换时延较大,对于实时性要求较高的业务无法适用.本文分析比较了目前移动IPv6常用的切换时延优化方法,提出了一种自适应快速层次移动IPv6切换时延优化方法,减小了移动IPv6切换时延,提高了网络的性能.     

超密集分簇网络中基于预测门限滞后余量可调的切换算法

在第五代移动通信(5G)系统中,大规模MIMO天线和超密集部署网络是实现高吞吐量的两种方式。针对超密集网络的切换管理的问题,该文基于网络分簇的思想提出了根据终端设备运动情况动态调节滞后余量的切换管理算法。在该算法中,基于小基站分簇化管理的前提,用户设备在小区间切换分为预切换和正式切换两个阶段,预切换阶段完成最佳目标小区选择、小区资源预留和预鉴权等操作,正式切换阶段根据预切换阶段监测的设备速度动态调节切换门限的滞后余量。仿真结果表明了该算法可以有效降低设备的切换时延和切换失败率。     

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。