基于GPRS的集装箱码头数据实时传输系统

针对集装葙码头作业过程中实时数据传输的需求,采用Java开发并实现了基于GPRS(EGPRS)网络的数据实时传输系统.阐述了系统的总体设计方案,重点对无线终端处理器资源和无线信道的特点进行了分析,在此基础上设计和优化了终端系统、终端与内网数据库的连接及通信流程.目前该系统在集装箱码头投入运用,成功地实现了无线终端与主控中心的数据实时传输.     

基于802.11协议的节能技术

无线终端的连续工作时间受电池容量的制约,产业界一直在寻求通过采用节能机制来延长终端工作时间的方法.介绍并分析了802.11基本节能协议PSM,探讨了针对其不足而提出的几种典型改进协议,阐述了节能技术所面临的困难,指出了节能研究的发展方向.     

基于GPRS的LED实时更新系统

针对传统LED显示屏存在的问题,提出了一种实时的基于GPRS的无线控制LED显示屏的方法,该方法具有易于控制、使用简单等特点.通过将计算机或者手机终端发送的信息传送给GPRS模块进行处理,可以快速、实时地在LED中显示信息.实际应用证明了提出方法可以在各种恶劣的环境下进行有效的信息传送和处理,已经被广泛地应用于居民小区用户的户外信息发布和公交车车载信息的发布,并取得较好的使用效果和经济效益.     

基于ZigBee的隧道照明智能控制系统研究与实现

针对普通隧道照明能源浪费严重、有线调光布线复杂等问题,设计了一种智能照明控制系统。该系统的主控制器中建立了模糊算法计算出当前隧道内需要的亮度值,系统通过ZigBee无线通信实现灯具0～10 V智能调光、电源开关控制和灯具故障自动检测与定位的功能。基于节能和智能化的设计目标,给出了由主控制器到协调器再到无线节点(包括路由器和终端控制器)的总体设计方案;详细阐述了基于CC2530芯片的协调器和无线节点的软硬件设计及无线组网技术,重点制定了主控制器与协调器之间的通信协议。湖南5条隧道的实际运行效果表明,该系统能够满足隧道照明要求并保证行车安全,与传统隧道照明相比,节能率达到55%。     

基于大数据的火灾智能预警系统

传统基于GSM蜂窝网的无线火灾预警系统由于成本高、感知终端电池耗电快等原因,一直很难得到大规模的应用.而LPWAN技术的快速发展,极大地降低了系统成本和感知终端的能耗,推动了火灾智能预警系统的快速发展.本文设计了一种基于大数据的无线火灾智能预警系统,通过该系统不但能够及时发现火灾,实时掌握火灾发生位置,还可以实现多个部门及个人的联动.实际使用结果表明,该系统不但通信成本低、电池寿命长,而且有效地降低了城市火灾发生率,提高了城市火灾救援效率和消防服务水平,并得到了广泛的推广和应用.     

一种基于公钥技术的3G安全体系结构及其实现

通过分析3G安全体系结构和移动通信系统的安全威胁,得出了3G体系结构存在的安全隐患。针对这些安全隐患,结合WPKI的相应特点,该文提出了一种基于SSL握手协议的用户与服务网络的AKA机制,即在3G体系结构中部署WPKI体系,使得无线终端侧实现了私密性、数据完整性等保护功能。最后模拟实现了一套完整的鉴权认证过程,实验结果表明:该机制能够很好地完成无线终端侧和服务网络之间双方的身份认证、加密传输、完整性保护等在3G安全体系中非常必要的功能。     

IEEE 802.11宽带无线局域网负载均衡优化研究*

在基于IEEE 802.11的宽带无线局域网中,随着终端STA的接入、移动和无线信道的时变性,各个接入点（AP）的负载将会产生差异,需要负载均衡优化机制平衡各个AP的差异,以达到网络资源的最大利用率。详细讨论了无线局域网中用到的几种负载均衡机制,分析了各自的优缺点,结合这些特点给出一种新的负载均衡机制。该机制能较准确地统计终端业务信息,降低切换失败风险,快速达到APs之间的负载均衡,优化提高网络整体性能。     

IEEE802.16中基于非实时业务的节能算法

IEEE802.16系统中采用节能机制（PSM）来延长移动设备的电池使用寿命。针对非实时业务,IEEE802.16e和IEEE802.16m中的节能机制,通过令睡眠窗口指数倍增长来进行休眠,牺牲了大量的数据包响应时间来换取节能效果。为此,根据数据包到达的平均时间间隔,提出了一种动态设定移动终端（MS）睡眠周期的休眠算法nPSM。由基站（BS）在数据包到达时计算数据包平均到达间隔,并在下一次与移动终端通信过程中,通过下行数据包以捎带的方式将该信息传递给移动终端,作为后续休眠周期的长度。结合数学分析和仿真实验,验证了所提休眠算法相比现有针对非实时业务的节能算法,在低通信负载下,在减少数据包响应延时的同时提高了节能效果。     

基于ZigBee和Android手机的无线监控系统设计

针对智能家居、环境监测等对实时性的要求,提出了一种将近距离无线接入技术与Android、嵌入式技术相结合的无线监控系统设计方案;在高性能嵌入式平台上实现Wifi、ZigBee的接入,根据实际应用环境的需要,选用相应传感器实现对环境变量的数据采集,通过ZigBee无线组网方式进行数据收发;另外,将Android手机终端通过Wifi与嵌入式平台建立连接并实现数据传输,ZigBee终端接收无线传感器节点发出的数据,通过协调器将数据信息发送给嵌入式平台,数据经过处理以后反馈给智能手机终端,手机端根据接收到的数据进而输出相应的指令;文中介绍了系统的软件设计流程,对系统整体实验证明节点性能良好、通讯距离较为理想,该系统具有较好的通用性,能够满足实时性的要求.     

基于混合特征指纹的无线设备身份识别方法

无线网络利用开放性的无线信道传输数据,因此容易遭受设备假冒攻击和通信数据伪造攻击,而防范此类攻击需要精准的设备识别.基于信道状态信息(channel state information,CSI)指纹的设备识别技术利用无线信道特征来识别设备.由于CSI提供细粒度的信道特征,并且可以从OFDM无线设备中轻松获取,因此该技术受到广泛的关注.但是反映无线信道特征的CSI指纹会随着终端的位置和所处环境的改变而改变,并且现有技术通常将机器学习用于指纹匹配以追求高识别准确率,随之而来的高计算复杂度使其无法在计算能力有限的嵌入式设备中实现.针对上述问题,提出了 一种基于混合特征指纹的设备身份识别方法,包含终端接入时和通信时的设备识别在接入时,引入了与终端外界因素无关的数据包到达时间间隔分布(packet arrival interval distribution,PAID)指纹进行识别,以弥补CSI指纹的缺陷;在通信时,借助CSI可以逐包获取的特点,从每个报文中提取CSI指纹并进行实时识别.同时,提出了一种计算复杂度较低的指纹匹配方案,以保证在计算能力有限的设备中也能快速且准确地识别终端在树莓派上实现了设备识别原型系统并开展了实验,实验表明:该系统在接入时和通信时的识别准确率最高可达98.17％和98.7％,通信时单个数据包的识别时间仅需0.142 ms.     

Wireless GINI: an educational platform for hosting virtual wireless networks

We describe Wireless GINI, a wireless platform for hosting virtual networks. Wireless GINI Is Not Internet (GINI) allows each virtual network to define its own topology and network configuration, while amortizing costs by sharing the physical infrastructure. The platform also creates mechanisms to readily integrate physical wireless devices into a deployed network. The platform supports a diverse combination of network elements that are all integrated into one custom Internet. The platform seamlessly integrates process‐emulated components running on the user machine, wireless mesh overlays deployed on the wireless platform, and generic wireless devices connected to the user's custom network. Wireless GINI provides a user‐friendly interface that makes the physical setup process completely transparent to the user. A centralized server is used to provide this transparency, handle user requests, and automatically provision the shared physical infrastructure. We describe the design and implementation of Wireless GINI. Moreover, we evaluate the performance of the platform and suggest several educational experiments that can be conducted on this new platform. A detailed survey of the existing toolkits and platforms and a comparison with Wireless GINI are also provided. Copyright © 2016 John Wiley & Sons, Ltd.     

超密集边缘计算网络中面向能耗优化的任务卸载方法

传统网络架构部署下的边缘服务器难以满足大规模用户设备的接入和通信质量要求。为增加网络容量,提高频谱利用率,通过密集化基站的部署,构建一种面向超密集边缘计算网络的任务卸载优化模型。面对信道状态的变化、移动设备的动态需求以及服务器和频谱资源的有限性对任务卸载带来的挑战,结合任务类型和服务器的计算能力,并考虑信道状态变化、移动设备的动态需求以及干扰约束对卸载策略的影响,提出一种基于自适应模拟退火遗传（AGASA）算法的任务卸载方法,在满足任务截止期限的同时,对任务卸载能耗进行优化。同时,为得到最优上传功率,采用黄金分割算法解决功率控制问题,从而降低传输能耗。实验结果表明,AGASA算法在信道状态变化时可保证通信质量和计算效率,相比混合遗传粒子群算法,能够在满足截止期约束的同时使卸载能耗降低15.56%。     

Cost-based cache replacement and server selection for multimedia proxy across wireless Internet

Multimedia proxy plays an important role in multimedia streaming over wireless Internet. Since wireless network exhibits different characteristics from the Internet, multimedia proxy caching over wireless Internet faces additional challenges. In this paper, we present a study of cache replacement for a single server and server selection for multiple servers across wireless Internet. By considering multiple objectives of multimedia proxy, we design a unified cost metric to measure proxy performance in wireless Internet. Based on the defined unified cost metric, we propose a novel replacement algorithm for single-server and a new server-selection policy for multiple servers to improve the end-to-end performance such as throughput, media quality, and start-up latency. To effectively handle errors occurred on wireless link, channel-adaptive unequal error protection is deployed according to distinct quality of service requirements of layered or scalable media. Simulation results demonstrate that our approaches achieve significantly better performance than the known cache-replacement algorithms and sever selection schemes, respectively.     

远程无线安全接入平台的设计与实现

该文介绍了一种基于L2TP/IPSec VPN的远程无线安全接入平台的设计与实现。服务器端使用基于Linux 2.6内核的Openswan和l2tpd,客户端选用基于Windows Mobile操作系统的智能手机。实现的平台系统能够保证用户数据传输的安全性,能够实现动态分配内网虚拟IP地址。服务器端使用的都是开源软件,远程客户端使用GPRS/CDMA等公众无线网络进行接入,因此具有较低的成本和强大的功能,同时有很强的扩展性。     

New wireless connection between user and VE using speech processing

This paper presents a novel speak-to-VR virtual-reality peripheral network (VRPN) server based on speech processing. The server uses a microphone array as a speech source and streams the results of the process through a Wi-Fi network. The proposed VRPN server provides a handy, portable and wireless human machine interface that can facilitate interaction in a variety interfaces and application domains including HMD- and CAVE-based virtual reality systems, flight and driving simulators and many others. The VRPN server is based on a speech processing software development kits and VRPN library in C++. Speak-to-VR VRPN works well even in the presence of background noise or the voices of other users in the vicinity. The speech processing algorithm is not sensitive to the user’s accent because it is trained while it is operating. Speech recognition parameters are trained by hidden Markov model in real time. The advantages and disadvantages of the speak-to-VR server are studied under different configurations. Then, the efficiency and the precision of the speak-to-VR server for a real application are validated via a formal user study with ten participants. Two experimental test setups are implemented on a CAVE system by using either Kinect Xbox or array microphone as input device. Each participant is asked to navigate in a virtual environment and manipulate an object. The experimental data analysis shows promising results and motivates additional research opportunities.     

Green software requirements and measurement: random decision forests-based software energy consumption profiling

This paper proposes an explicit definition of green software requirements and a tool to support their evaluation. The proposed evaluation tool describes the green efficiency by considering the energy consumption as the main aspect to be studied during the development stage. This approach consists of building a multiple regression model, by using a supervised learning algorithm, in order to reproduce the energy consumption pattern of devices at different workload circumstances. The energy consumption model is then deployed to estimate the impact of software applications based on their resource usage. Our work has been validated on desktop and mobile devices. The experiments show the effectiveness of the proposed energy profiling tool that provided relevant information on the energy consumption of software applications.     

基于SMTP协议的嵌入式邮件通知软件

为了实时监测运行在户外恶劣环境中的嵌入式设备的运行状态信息,本文设计并实现了基于SMTP协议的嵌入式邮件通知软件.邮件通知软件是运行在带有GPRS网络的嵌入式设备上,邮件通知软件首先检测并获得设备的相关告警信息,生成指定格式的邮件内容和邮件标题,然后在设备与邮件代理服务器之间通过GPRS网络建立TCP连接,按照SMTP协议的语法结构发送告警信息邮件给指定邮件代理服务器.最后设计了相关实验来测试邮件通知软件检测设备告警信息和发送告警邮件的可靠性.实验结果表明基于SMTP协议的嵌入式邮件通知软件能够满足实际运行环境的要求,同时软件具有较好的可靠性和稳定性.     

集群和负载均衡技术在省级数据集中的应用研究

介绍了集群和负载均衡技术的概念,在省级数据集中实施过程中利用集群技术部署了主机、数据库和中间件系统,有效克服了单点故障.重点分析了中间件系统部署 Web 集群和 App 集群中软件代理服务器和硬件负载均衡服务器的区别,对省级集中系统的软件代理服务器性能提供了全面测试方案,得出的测试结论为:软件代理服务器能承载的合适在线数为一有限值,较大在线用户应使用硬件设备进行负载均衡,并对硬件负载均衡设备 BIG IP F5 的实施进行了详细描述.     

CSNEO:协同服务器与网络能耗优化的VM映射算法

已有针对虚拟机映射问题的研究,主要以提高服务器资源及能耗效率为目标.综合考虑虚拟机映射过程中对服务器及网络设备能耗的影响,在对物理服务器、虚拟机资源及状态,虚拟机映射、网络通信矩阵等概念定义的基础上,对协同能耗优化及网络优化的虚拟机映射问题进行了建模.将问题抽象为多资源约束下的装箱问题与二次分配QAP问题,并设计了基于蚁群算法ACO与局部搜索算法2-exchange结合的虚拟机映射算法CSNEO来进行问题的求解.通过与MDBP-ACO、vector-VM等四种算法的对比实验结果表明:CSNEO算法一方面在满足多维资源约束的前提下,实现了更高的虚拟机映射效率;另一方面,相比只考虑网络优化的虚拟机放置算法,CSNEO在实现网络优化的同时具有更好的能耗效率.     

Energy-aware allocation for delay-sensitive multitask in mobile edge computing

With lower network latency and powerful hardware, mobile edge computing (MEC) is effective for computation-intensive and delay-sensitive tasks. The rising energy and low-latency demands of mobile applications for MEC pose challenges to task allocation. In this work, we consider computation offloading in MEC that is composed of a set of mobile devices, each with multiple tasks to offload to a nearby MEC server, with both single and multiple access points (APs). With multiple APs deployed, each mobile device can directly communicate with one or more APs, and their tasks can offload to different MEC servers that are within direct communication range. By considering binary computation offloading mode and limited subchannels, we formulate the multitask allocation problem as an integer programming problem, with the objective of minimizing the total energy consumption of all mobile devices while meeting deadline requirements. To solve this complicated problem, we propose efficient algorithms for single and multiple APs, and analyze related properties, including the approximation ratio and complexity. Experiments show that the algorithm can find high-quality solutions in a short time.