一种新的无线网络通信技术Zigbee

Zigbee是一种新兴的无线组网通信技术。其设想是发展一种易布建的低成本无线网络,在低速率下同时保持低耗电性。Zigbee在工业控制、家庭智能化、无线传感器网络等领域有广泛的应用前景。文章着重介绍该技术的特点,包括协议栈架构、组网方式以及在低功耗、低成本上所体现的突出优势;举例说明已推出的Zigbee芯片产品特点,并与蓝牙、WiFi、UWB等其他一些无线组网通信技术在距离、速率上进行比较。

4G无线网络通信技术在大柳塔煤矿的应用

针对矿井出现的各信息化系统复杂、多系统数据资源共享困难、井下维护工作繁重等问题,借助4G无线通信技术,将电信网、广播电视网与互联网进行"三网融合",实现了井下多系统网络互联互通、通信设备集中管理、数据资源合理共享等功能,开启了全矿井通信系统的"一网一站"式服务。4G无线网络技术在大柳塔煤矿的成功实践,不仅提高了煤矿通信联络系统的可靠性,而且也强化了矿井各系统间的高度融合,给安全生产提供了有效保障。

短距离无线网络通信技术及其应用

随着科学技术的飞速发展,计算机的电子技术应用领域渐渐扩宽,数据通信技术需求量急速增加,短距离无线网络通信设备逐渐得到各行各业的开发和利用。本文主要阐明了短距离无线网络通信技术的通信的类型,主要研究了人民生产生活中短距离无线网络通信技术的应用。

关于无线网络及发展前景探讨

近年来,随着个人数据通信的发展,功能强大的便携式数据终端以及多媒体终端得到了广泛的应用。为了实现使用户能够在任何时间、任何地点均能实现数据通信的目标,要求传统的计算机网络由有线向无线、由固定向移动、由单一业务向多媒体业务演进,由此无线网络技术得到了快速的发展。在互联网应用快速普及的今天,无线网络技术已成为通信发展的重要新兴领域。无线技术使得人们使用品种广泛的设备在世界任何位置访问数据的愿望成为可能。

基于SIP协议的异构无线传感器网络管理

近年来,无线传感器网络发展迅速,大多数无线传感器网络拥有基于独立方式的管理机制,会影响系统的互操作性和可扩展性。本文中,将提出利用基于通用平台的会话初始化协议(SIP)来管理异构的无线传感器网络。利用开源的Sofia-SIP库来开发SIP用户代理,采用OpenSER作为SIP服务器。另外可以使用PHP脚本开发一个支持sip消息发送的网络平台,发送作为控制消息的SIP即时消息,适用于手机上的web浏览器。实验结果表明,设计的系统可以适用于不同类型的的网络,例如IEEE802.11和IEEE802.15.4。

无线安全生产监察管理信息系统应用方案

本文介绍无线安全监察管理信息系统在煤矿应用方案,阐述无线安全监察管理信息系统系统总体架构、技术路线、系统功能。

基于Android的智能家居终端控制系统

为了更好地满足用户对生活居住需求,给用户提供更好的对智能家用电器的控制体验,提升家居生活质量,基于Android的手机平台和平板电脑,设计了基于Android的智能家居终端控制系统。该系统建立在Android平台上,利用Android系统支持的各种资源建立并实现。用户可以使用智能手机实现对智能家用电器的远程控制。该系统成本低,操作灵活,界面友好,经实际使用获得了很好的用户体验。

基于嵌入式互联网的远程智能喷雾控制系统设计

为提高设施农业植保作业智能管控能力,该文提出一种基于STM32F101和STM32F103嵌入式技术,结合4G互联网、局域WIFI通信技术及超声波靶标检测算法,能够便捷地对设施作业装备远程视频与控制的方案,达到人机分离与精准施药的目的。该系统在Eclipse和Keil-uvision4开发环境下采用Socket和多线程技术实现双向通信,以TCP通讯协议为媒介,Android端和客户端通过互联网或无线网卡转接移动路由实现远程智能喷雾控制。试验结果表明:1)Android端能够在LAN或Internet中实现智能喷雾装备的近远程控制,软件界面回传状态无卡顿、延时发生,能够准确发射控制指令,实现了对靶标间歇性施药管控;2)系统建立的双向心跳包能够在通信故障情况下迫使喷雾装备处于休眠状态,经测试,心跳包设定时间与喷雾装备休眠响应时间平均相对误差不超过5.50%;3)采用视频帧对冠层中线定位,借助超声检测算法确定风送距离参数且建立冠层体积模型。试验发现,冠层密度对体积测量结果有显著影响,但总体测量准确度可达94.67%。该研究对其他农机装备的智能化管控研究有参考意义。

基于MEMS的车辆预警系统及其姿态算法设计

针对车辆倾斜角度过大时产生侧翻和车辆在侧翻时能够得到及时救援这一现象,设计了基于嵌入式技术,无线网络通信技术,车辆实时定位技术以及车辆侧翻预警算法的综合系统。为验证系统算法的有效性,将MLR建模预测方法与自回归模型预测方法在未来1 s^2 s的LTR预测值并与车辆实际LTR值作对比。实验结果显示,MLR建模预测方法在两种极端情况下的平均相对误差比自回归模型预测方法的平均相对误差分别低了0.66%、1.35%。

New Optimal Power Allocation for Bidirectional Communications in Cognitive Relay Network Using Analog Network Coding

Cognitive radio and cooperative communication can greatly improve the spectrum efficiency in wireless communications.We study a cognitive radio network where two secondary source terminals exchange their information with the assistance of a relay node under interference power constraints.In order to enhance the transmit rate and maintain fairness between two source terminals,a practical 2-phase analog network coding protocol is adopted and its optimal power allocation algorithm is proposed.Numerical results verify the superiority of the proposed algorithm over the conventional direct transmission protocol and 4-phase amplify-and-forward relay protocol.

Asymptotic Analysis of Transmission Capacities for Overlaid Spread-Spectrum Wireless Networks

We study the transmission capacities of two coexisting spread-spectrum wireless networks (a primary network vs. a secondary network) that operate in the same geographic region and share the same spectrum. We defi ne transmission capacity as the product among the density of transmissions, the transmission rate, and the successful transmission probability. The primary (PR) network has a higher priority to access the spectrum without particular considerations for the secondary (SR) network, while the SR network limits its interference to the PR network by carefully controlling the density ofits transmitters. Considering two types of spread-spectrum transmission schemes (FH-CDMA and DS-CDMA) and the channel inversion power control mechanism, we quantify the transmission capacities for these two networks based on asymptotic analysis. Our results show that if the PR network permits a small increase ofits outage probability, the sum transmission capacities of the two networks (i.e., the overall spectrumefficiency per unit area) will be boosted significantly over that of a single network.

Performance of beacon safety message dissemination in Vehicular Ad hoc NETworks (VANETs)

Currently, there is a growing belief that putting an IEEE 802.11-like radio into road vehicles can help the drivers to travel more safely. Message dissemination protocols are primordial for safety vehicular applications. There are two types of safety messages which may be exchanged between vehicles: alarm and beacon. In this paper we investigate the feasibility of deploying safety applications based on beacon message dissemination through extensive simulation study and pay special attention to the safety requirements. Vehicles are supposed to issue these messages periodically to announce to other vehicles their current situation and use received messages for preventing possible unsafe situations. We evaluate the performance of a single-hop dissemination protocol while taking into account the quality of service (QoS) metrics like delivery rate and delay. We realize that reliability is the main concern in beacon message dissemination. Thus, a new metric named effective range is defined which gives us more accurate facility for evaluating QoS in safety applications specifically. Then, in order to improve the performance, the effects of three parameters including vehicle's transmission range, message transmission's interval time and message payload size are studied. Due to special characteristics of the safety applications, we model the relationship between communication-level QoS and application-level QoS and evaluate them for different classes of safety applications. As a conclusion, the current technology of IEEE 802.11 MAC layer has still some challenges for automatic safety applications but it can provide acceptable QoS to driver assistance safety applications.

Power Versus Bandwidth Efficiency in Wireless Communications:from Economic Sustainability to Green Radio

We carry out a comprehensive analysis of a range of wireless network efficiency considerations. Firstly, we explore the properties and the implications of the power-versus bandwidth-efficiency criteria. Secondly, we perform a detailed top-down analysis of a typical commercial wireless network, which emphasizes the inherent differences between the aforementioned two efficiency metrics, while demonstrating that the appropriate choice of the network optimization criterion can have a profound effect on the overall network performance. Finally, we address the issue of resource management and its impact on the definition of the overall system efficiency. Our results suggest that no substantial area spectral efficiency gains beyond those exhibited by the 2G cellular technol- ogy may be economically achieved, and hence, no significant economic gains may be realized by simply increasing the bps/Hz bandwidth efficiency. In contrast, manifold utility and throughput gains as well as substantial Quality of Service enhancements may be attained by the appropriate combination of improved power efficiency, bandwidth expansion as well as the appropriate evolution of the networking paradigm.

An overview of intelligent selection and prediction method in heterogeneous wireless networks

Heterogeneous wireless access technologies will coexist in next generation wireless networks.These technologies form integrated networks,and these networks support multiple services with high quality level.Various access technologies allow users to select the best available access network to meet the requirements of each type of communication service.Being always best connected anytime and anywhere is a major concern in a heterogeneous wireless networks environment.Always best connected enables network selection mechanisms to keep mobile users always connected to the best network.We present an overview of the network selection and prediction problems and challenges.In addition,we discuss a comprehensive classification of related theoretic approaches,and also study the integration between these methods,finding the best solution of network selection and prediction problems.The optimal solution can fulfill the requirements of the next generation wireless networks.

A New Radio Access Scheme for Co-operation Networks in B3G Wireless Communications

The paper discusses the signifi cance and development foreground of co-operation among heterogeneous networks in composite radio context for B3G wireless communications. The concept of composite reconfigurable wireless network is introduced in the paper, and the development of future wireless communication systems is also discussed. The basic confi guration framework of the network interoperation is given, and the functions of important parts are analyzed. A management platform for co-operation between WLAN and cellular network is introduced, adding several models to the original systems. Furthermore, new radio access schemes for different types of Mobile Terminals (MTs) are proposed. Particularly, Spectrum Sharing (SS) between WLAN and cellular networks is discussed. Here, a new radio access scheme and channel assignment mechanism with code-division duplex (CDD) and Frequency Hopping (FH) technologies are raised, for the purpose of avoiding interference between heterogeneous networks. Finally, the performance of the above radio access schemes is analyzed, and simulation results proved its validation.

A 5G Virtualized RAN Based on NO Stack

The virtualized radio access network(v RAN) could implement virtualized baseband functions on general-purpose platforms and expand the processing capacity of the radio access network(RAN) significantly.In this paper,a Not Only Stack(NO Stack) based vR AN is proposed to be employed in the fifth generation(5G) mobile communication system.It adopts advanced virtualization technologies to maintain flexible and sustainable.The baseband processing and storage resources should be sliced and orchestrated agilely to support multi radio access technology(multiRAT) .Also it is analyzed and demonstrated by different use cases to validate the benefits.The proposed v RAN reduces signaling overheads and service response time in the bearer establishment procedure.Concluded from the analyses and demonstrations,the NO Stack based v RAN could support multi-RAT convergence and flexible networking effectively.

Capacity Analysis and Optimization of Cognitive Ultra Wideband Networks

The integration of cognitive radio and Ultra wideband (UWB) networks has attracted lots of research interests. Cognitive UWB networks not only provide very high data rates but also guarantee the uninterrupted communication of primary system operated in the same frequency band. In this work, the problem of the capacity analyses of cognitive UWB networks is investigated. Different from the conventional cognitive spectrum sharing model which can only utilize the idle spectrum hole, the cognitive UWB system can operate adaptively based on spectrum sensing results. Taking into account several factors such as the transmission power constraint of UWB, the interference constraint of the receivers in primary systems, the secondary UWB network capacity problem is modeled as a convex optimization problem over the transmission power. The optimal power allocation strategy and algorithm are derived based on this optimization problem. Two cases (Perfect Spectrum Sensing and Imperfect Spectrum Sensing) are studied in the paper. Numerical simulation results show that the proposed adaptive power allocationscheme improves the ergodic and outage capacity under both transmission power and interference constraints compared with constant transmission power scheme.

Quality of Service Improvement for High-Speed Railway Communications

With the fast development of highspeed railways,a call for fulfilling the notion of communication at "anytime,anywhere" for high-speed train passengers in the Train Operating Control System is on the way.In order to make a realization of that,new railway wireless communication networks are needed.The most promising one is the Long Term Evolution for Railway which will provide broadband access,fast handover,and reliable communication for high mobility users.However,with the increase of speed,the system is subjected to high bit error rate,Doppler frequency shift and handover failure just like other system does.This paper is trying to solve these problems by employing MIMO technique.Specifically,the goal is to provide higher data rate,higher reliability,less delay,and other relative quality of services for passengers.MIMO performance analysis,resource allocation,and access control for handover and various services in a two-hop model are proposed in this paper.Analytical results and simulation results show that the proposed model and schemes perform well in improving the system performances.

Event-Oriented Dynamic Security Service for Demand Response in Smart Grid Employing Mobile Networks

Equipped with millions of sensors and smart meters in smart gird,a reliable and resilient wireless communication technology is badly needed.Mobile networks are among the major energy communication networks which contribute to global energy consumption increase rapidly.As one of core technologies of smart grid employing mobile networks,Demand Response(DR) helps improving efficiency,reliability and security for electric power grid infrastructure.Security of DR events is one of the most important issues in DR.However,the security requirements of different DR events are dynamic for variousactual demands.To address this,an event-oriented dynamic security service mechanism is proposed for DR.Three kinds of security services including security access service,security communication service and security analysis service for DR event are composited dynamically by the fine-grained sub services.An experiment prototype of the network of State Grid Corporation of China(SGCC) is established.Experiment and evaluations shows the feasibility and effectiveness of the proposed scheme in smart grid employing mobile network.