卫星传感器网络的定位算法及在应急通信中应用

针对应急通信系统的需求,提出了一种基于卫星传感器网络的应急监测与通信系统.介绍了卫星传感器网络的基本概念和网络结构,基于RSSI信息的多重覆盖策略,提出了一种适于卫星传感器网络的非测距定位算法-MOLA.仿真结果表明,该定位算法能够满足应急通信与监测系统对定位性能的需要.     

车联网环境下的4G和DSRC异构网络切换机制研究

面向车联网的实际应用需求,构建了一种高速公路环境下的基于4G和DSRC的异构网络通信场景。针对车辆在该场景下可能会在不同网络信道间频繁发生垂直切换导致较高的传输时延和丢包率的问题,在分析研究基于4G与DSRC的高速公路异构网络切换过程的基础上,引入网络跳数、连接次数和行驶轨迹作为切换判决条件,基于TREBOL路由协议设计了一种异构网络垂直切换算法。最后利用Veins仿真平台对提出的异构网络垂直切换算法的切换性能进行对比测试分析。测试结果表明,与基于RSSI的异构网络垂直切换方法相比,所提切换算法能增大车辆与DSRC网络连接的持续时间,并有效减少"乒乓效应"。     

基于用户体验的VLC/WiFi异构网络切换算法

针对可见光通信(VLC)与WiFi组成的异构网络中的网络选择问题,现有工作大多仅关注实际物理网络指标的优化,如信干噪比(SINR)和吞吐量等,而忽视了终端用户的异构需求和服务体验。基于此,该文提出了一种以用户体验质量(QoE)为优化目标的网络切换算法。该算法首先基于平均主观评分(MOS)机制建立离散化的QoE等级模型,然后根据不同网络对应的实际QoE水平给出了相应网络切换准则,当且仅当新网络使得用户QoE等级提升时才进行网络切换,从而在一定程度减小盲目追求容量优化引起的网络切换开销。仿真结果表明,该算法相比现有算法能够在保证QoE水平的前提下显著减小整体的网络切换次数,从而降低网络开销,提升网络性能。      

异构无线网络的自适应垂直切换判决算法

在未来的异构环境中,网络间的垂直切换将对QoS保证产生重要影响。针对移动终端在异构网络间切换不理想的问题,提出了一种自适应的垂直切换判决算法。采用基于用户多应用的代价函数对接入网络进行评估与选择,综合考虑移动终端当前的电池电量,判断当前业务是否需要进行网络切换,使移动终端能自适应地进行切换判决。仿真结果表明,该算法可以有效地延长移动终端的工作时间,减少乒乓效应,提高系统的切换性能,改善业务的QoS。     

无线传感器网络中一种能量有效的抗干扰路由算法

近年来,作为物联网重要支撑的无线传感器网络受WiFi等异构系统的干扰日益严重,传统路由协议在该干扰环境下的性能急剧下降。针对该问题,本文在引入动态簇的多信道策略的基础上,综合考虑信道切换代价、频谱受干扰程度、节点剩余能量、距离等因素提出了一种认知频谱干扰的能量有效的路由（CSIEE）算法。仿真结果表明,该路由与EEPA、AODV、AODV-EA路由相比,有效地节约了传感器节点能量,延长了网络生命周期。     

改进的自适应物联网技术节能优化控制仿真

研究异构传感网节能优化拓扑控制优化问题.在异构传感器网络中,每个传感器节点普遍存在初始能量异构,节点在无线通信过程中通信链路异构等异构现象.为了延长网络的生存期,提出一种自适应优化异构无线传感器网络拓扑结构控制算法.算法主要难点技术问题在于对参数E的选择控制问题.该算法基于传输数据跳数和相邻传感器之间通信距离,依据相似三角形几何原理,结合具体应用场景对传感器节点的分簇、成簇等操作进行自适应优化控制.仿真实验表明,改进的算法可以高效控制给定数据采集监测区域所有节点的网络拓扑同时极大地延长了异构传感网的生命周期.     

基于可见光通信的室内光电混合网络组网关键技术

针对可见光通信在室内的应用,分析了采用可见光与无线射频构成光电混合网络的可行性,提出了一种可行的网络架构;指出了该网络架构组网中的关键技术问题,并针对网络中的光源布局、多址接入、小区切换、异构网络融合等给出了技术路线。     

异构网络中基于终端决策的通用垂直切换算法

垂直切换是异构网络中的关键技术,目前已有的垂直切换算法大多是针对特定的网络或切换过程的某个环节,提出一种与网络类型无关的通用垂直切换算法,仿真结果表明该算法在支持多任务,有效利用能量方面比传统方法有很大的改进.     

异构无线网络资源管理与切换控制技术

随着通信技术的发展,新型业务逐渐增多,传统的通信网络无法满足各种业务之间巨大的性能需求差异,未来的通信网络逐渐向异构网络进行发展。针对异构网络中资源调配与垂直切换的问题,利用虚拟网络技术与资源虚拟化技术设计了异构网络中的无线资源管理方法,并设计了子网间垂直切换算法。该算法利用层次分析法与熵权法得到各网络参数的综合权值,加权得到各网络的效用值并依此选择最优网络。通过搭建系统平台验证了设计的异构无线网络的有效性,为后续异构无线网络的研究提供了参考。     

异构网络融合场景下车联网的移动性管理和资源管理

摘要：针对异构网络融合场景下车联网的特点,研究了车联网中的移动性管理技术和资源管理技术。在介绍物联网及车联网基本概念的基础上,分析了车联网中异构网络融合的应用场景,通过研究车联网中的通信设备、通信形式、组网方式等,提出了车联网的网络架构。与一般异构网络相比,车联网中车辆移动速度快,造成车辆接入公共网络时频繁切换的问题,为此,研究了车联网中的移动性管理技术。车联网中通信设备以及通信形式的多样化带来了多样化的业务需求,针对不同优先级业务提出了车联网中基于优先级的资源管理技术,即在异构网络的资源管理中必须保证高优先级业务在资源分配、接入控制、网络选择等方面始终处于优先状态。     

Intelligent Vertical Handoffs between Heterogeneous Communication Networks

1IntroductionWith the increasing demand for mobile access ,theInternet has to provide not only li mited mobility,suchas WLAN[1 ~3]access ,but also worldwide mobility,asexemplified by Mobile IP[4 ~7]to meet the user require-ments in terms of data rate and mobility.In particular ,it is desired that when a user stays in the hotspot cov-ered by WLAN, he can access the Internet throughWLAN,and when he goes out of the hotspot ,the on-going connection should not be dropped,but is insteadhanded …     

Vertical handoff algorithm in heterogeneous networks for reducing interference

A vertical handoff decision algorithm in heterogeneous networks composed of CDMA Cell Networks (CN) and Wireless Local Area Network (WLAN) is proposed to minimize the total interference in CDMA. The scope of WLAN is determined by minimizing interference and each communicating node shall handoff to WLAN as soon as it enters the scope. We first propose a model for heterogeneous networks, and based on it we obtain the close-form expression of interference. In order to minimize interference, we use simulation annealing method to get the WLAN radius, which is called basic algorithm. In order to reduce the interference further, we improve the basic and get the enhanced algorithm. Through numerical computing, we analyze the interference in condition of different call arrive rates, and results show that the enhanced can reduce interference more greatly than the basic.     

无线异构网络的垂直切换算法研究

以通用移动通信系统(UMTS)与无线局域网(WLAN)融合为例,研究无线异构网络的垂直切换算法。由于垂直切换算法应考虑因素的复杂性以及不同网络性能的各异性,有必要对现有算法作出归纳总结比较,并据此提出新的垂直切换算法。该算法以代价函数为基础,将稳定周期与切换目标网络和当前服务网络的效用函数联系起来,实现移动节点自适应的切换判决。提出的算法能有效减少不必要的切换,增强异构网络的适应性。     

Seamless Handoff Scheme Based on Pre-registration and Pre-authentication for UMTS–WLAN Interworking

Interworking issues between Universal Mobile Telecommunication System (UMTS) and Wireless Local Area Network (WLAN) have become a great matter of interest as an increasing number of mobile internet users require broadband wireless access to IP services in the wide area. In this paper, we present a practical UMTS–WLAN interworking architecture based on 3GPP standards and propose a seamless handoff scheme that guarantees low delay and low packet loss during UMTS–WLAN handoff. For low handoff delay, the proposed handoff scheme performs pre-registration and pre-authentication processes before layer 2 handoff. Moreover, it uses packet buffering and forwarding functions in order to reduce packet loss during the handoff period. On the above basis, detailed signaling procedures are presented, together with system requirements when a mobile terminal moves from UMTS to WLAN and vice-versa. Numerical results show that the proposed scheme performs well with respect to signaling cost, handoff delay, and packet loss compared with conventional schemes.     

融合的蜂窝网络/无线局域网中资源管理的性能分析

Wireless Local Area Network (WLAN) with high data bit rates can be used with cellular network to achieve higher level of Quality of Service (QoS) by sharing their total resources efficiently. The integration between cellular and WLAN networks should be ensured considering different channel allocation strategies of both networks and efficient resource management techniques should be developed. In this paper, we propose a new call admission scheme to use the coupled resource effectively. The proposed scheme, by taking the different resource sharing strategies for two access networks, limits the new, horizontal and vertical handoff voice and data call arrivals with respect to their call level QoS requirements. Numerical results show that the proposed integrated cellular/WLAN network model uses the resources more effectively and achieves all upper bound QoS requirements for voice and data users as compared with the non integrated network model.     

3G-WLAN融合网络中一种新的双模终端设计

设计了一种能够在3G与WLAN融合网络中智能切换的双模终端模型.为了实现两种网络之间的无缝切换,提出了网络接口选择算法.该算法通过提前注册和认证机制减少了垂直切换时延,并采用提前切换的方法减少了垂直切换时数据包丢失.仿真结果验证了设计和算法具有良好性能.     

Adaptive vertical handoff algorithm in heterogeneous networks

The integration of cellular network (CN) and wireless local area network (WLAN) is the trend of the next generation mobile communication systems, and nodes will handoff between the two kinds of networks. The received signal strength (RSS) is the dominant factor considered when handoff occurs. In order to improve the handoff efficiency, this study proposes an adaptive decision algorithm for vertical handoff on the basis of fast Fourier transform (FFT). The algorithm makes handoff decision after analyzing the signal strength fluctuation which is caused by slow fading through FFT. Simulations show that the algorithm reduces the number of handoff by 35%, shortens the areas influenced by slow fading, and enables the nodes to make full use of WLAN in communication compared with traditional algorithms.     

基于ARMA的无线传感器网络流量预测模型的研究

无线传感器网络(WSN)的流量预测研究对于WSN管理具有至关重要的意义。基于WSN的特点,结合自回归滑动平均(ARMA)模型,该文提出了一个面向WSN的流量预测算法。仿真结果表明,该算法具有较高的预测精度;利用本算法对WSN的多路径路由机制进行改进后,可进一步提高WSN的生存期。     

Using Chain of Mobile Access Gateway to Reduce Delay for PMIPv6 Protocol Applied in WLAN

Wireless LAN controller (WLC) is used to manage and control Access points (APs) in Wireless local area network (WLAN).Proxy mobile IPv6 (PMIPv6) protocol supports network-layer mobility in WLC based WLAN.However,it introduces extra delay in delivering packets from the APs to the WLC.We use Mobile access gateway (MAG) chain to reduce packet delay.The handoff delay and packet delivery delay under the proposed scheme are derived,based on which we formulate the delay minimization problem whose solution leads to the optimal MAG chain length.Numerical analysis results indicate that the proposed scheme outperforms the existing scheme in terms of delay in the case when the delay between Local mobility anchor (LMA) and WLC is relatively greater than the delay between two neighboring WLCs.The proposed scheme is able to reduce packet loss resulting from the traditional handoff procedure introduced in the PMIPv6 protocol and that due to delay limitation.     

面向WLAN的无线传感器网络网关设备及其接入机制

网关是实现无线传感器网络与其他基础网络（如移动通信网、电信网等）互联互通的重要设备。文章设计并实现了一种基于CC2420芯片的网关,实现了与传感器网络的通信,并利用无线网卡模块实现了网关设备与无线局域网的连接,克服了网关硬件设备布置的局限性,扩大了网关设备和无线传感器网络的应用范围。