基于RFID的无线语音控制系统

目前越来越多的智能家居进入人们的生活,如何对智能家居进行简单有效的控制是一个难题.针对这个问题,本文设计了一个无线语音控制系统.通过LD3320语音识别模块、STC11L08XE单片机、无线发射模块和无线接收模块,实现了语音控制家居启停.实验结果表明语音模块可以准确识别口令并通过无线发射模块发送信号,实时控制电器的电源通断,可以代替人工接触电源开关,更方便地控制家中电器.     

基于TDA5210的868MHz无线接收模块设计

为解决采用315 MHz或433 MHz 频段无线接收模块的系统,干扰源多,接收灵敏度低,设计调试复杂等问题,提出了一种868 MHz无线接收模块的设计方案.方案中采用英飞凌低功耗单芯片FSKIASK超外差无线接收器TDA5210,以及少量的外围分立器件.通过改善接收模块PCB中铜箔天线走向,提高接收灵敏度;在接收模块...     

关于无线传输系统的探讨

针对传统无线模块难以实现多跳传输的问题,本文提出了一种新的无线传输方案.该方案通过定义更加合理的数据帧格式,在传输过程中利用改进后的路由算法,实现了最佳路由选择,整体上提升了无线传输模块的传输能力.     

基于DS18B20的短距无线温度检测系统

基于一种新型单线可编程数字温度传感器DS18820的测温原理,以低功耗的MSP430F1611单片机为微控制器,设计了一种的短距无线温度检测系统,并通过无线模块nRF401实现数据的无线收发。给出了微控制模块、LCD显示模块、无线收发模块和温度传感器模块的设计以及系统的软件开发。实验结果表明：系统实现了短距、多点的温度检测;利用无线收发模块和CLD显示模块,节约了现场调试时间,实现了系统的便携式设计并提高了温控系统的稳定性;利用MSP430单片机的超低功耗以及DS18820的单线接口方式,实现了整个系统的低功耗设计,并简化了系统的结构。     

基于nRF905的智能照明控制系统

本文以Atmega16单片机和无线射频模块nRF905为核心,给出了一种基于无线局域网络的智能照明控制系统的软硬件设计.该系统采用RS232总线与PC上位机通信,通过无线射频收发模块与教室照明控制单元进行命令传输,实现短距离、多节点的无线控制.     

基于STC89C52的公交智能报站系统设计

设计一种由STC89C52单片机和n RF24L01无线模块等组成的自动报站系统。该系统主要由发射模块和接收模块两部分组成,接收模块通过接收无线模块发送的信号,再通过CPU发出指令,控制语音模块,从而达到自动识别、自动报站的功能。该系统解决了一对一的单信道信息发送接收模式,实现了一对多的多信道信息发送接收模式,在设计成本上有极大的优越性,提高了站台的利用率,减少空间的占用,实现了城市公交报站的智能化。     

应用nRF24L01设计的智能灭火小车

在此的设计采用AT89S52单片机,由n RF无线通信模块,多传感器检测模块,灭火设备模块和电源驱动模块组成。通过烟雾报警系统的无线发射模块与智能灭火车本身的无线接收模块之间建立的的无线通信迅速得到房间着火的信号,然后启动相应程序,通过超声波传感器测距检测前进,红外传感器寻找火源,实现完整的灭火过程。     

集成无线模块电子电气设备的EMC测试原则

越来越多的非无线设备增加了无线模块以实现网络通信功能,但这类集成无线模块后的非无线产品没有相应的电磁兼容(EMC)标准要求。文章介绍了集成无线模块电子电气设备的应用特点、已有EMC标准中对无线模块的要求、集成模式,研究分析了具体的EMC测试原则、测试方法、豁免频段,并结合相关案例讨论了测试原则。有利于后续标准的推广及宣贯,提高产品EMC测试的准确性及复现性。     

集成无线模块电子电气设备的EMC测试原则

越来越多的非无线设备增加了无线模块以实现网络通信功能,但这类集成无线模块后的非无线产品没有相应的电磁兼容（EMC）标准要求。文章介绍了集成无线模块电子电气设备的应用特点、已有EMC标准中对无线模块的要求、集成模式,研究分析了具体的EMC测试原则、测试方法、豁免频段,并结合相关案例讨论了测试原则。有利于后续标准的推广及宣贯,提高产品EMC测试的准确性及复现性。     

基于无线传感器网络的数据采集系统研究

设计一种新的基于无线传感网络的数据采集系统,其由电源模块、无线模块和控制模块组成。电源模块为无线模块和控制模块提供电能,无线模块使用智能总线协议或低功耗射频协议从传感器中采集数据,控制模块利用MSP430F4250微处理芯片控制无线模块的采集工作,并对所采集到的传感器数据进行处理,处理后的数据将传回无线模块,用户通过控制模块设置数据交互标准,对无线模块中处理后的传感器数据进行提取。实验结果表明,所设计的系统拥有极小的采集误差和极低的无线通信误码率,较好地实现了设计目标。     

认知无线电中的频谱接入技术

认知无线电是一种基于软件无线电的智能通信系统,它能够认知周围环境,并能通过一定的方法相应地改变某些工作参数来实时地适应环境,从而达到提高频谱利用率、缓解频谱资源紧张的目的.授权频段的频谱利用问题是认知无线电实现的关键技术之一.研究了授权频段的两种频谱利用方法:动态频谱接入和基于动态频谱接入模型之一的机会频谱接入.     

Efficient Internet traffic delivery over wireless networks

The high demand for wireless Internet connectivity has driven the development of highly efficient radio link technologies. However, their performance can be compromised by inadvertent interactions with the higher-layer TCP flow control protocol. Maximizing the performance of wireless links requires that mechanisms operating at every layer of the protocol stack interact efficiently. This article provides a brief tutorial of some of these radio link enhancements. It then outlines how higher-layer flow control protocols should behave, and provides techniques for taming the behavior of TCP, to ensure that the performance of lower-layer enhancements is not compromised.     

基于认知无线电技术的802.22标准

认知无线电技术能够监测到无线电环境中已存在的用户,同时监控频谱资源的使用情况,并能动态地调整各无线用户的传输参数,从而提高频谱资源的利用率。基于认知无线电技术的802.22标准要求在不损害已有电视设备服务的前提下,使用电视频带为非授权用户提供廉价的无线接入服务。对认知无线电技术和802.22标准结构进行了深入分析,并讨论了一些重点需要解决的问题。     

认知无线电中基于干扰温度的频谱探测技术

认知无线电的提出,能够在一定程度上提高频谱利用率,解决目前通信频谱资源紧缺的问题.频谱探测是认知无线电中的关键技术之一,通过频谱探测技术来检测授权用户的频谱空洞,以使得非授权用户能够有效利用.文章介绍了常用的基于干扰温度的探测模型以及频谱估计算法,进行了分析与总结,并且提出了目前频谱探测技术的不足之处.     

OFDM for cognitive radio: merits and challenges [accepted from open call]

Cognitive radio is a novel concept that enables wireless systems to sense the environment, adapt, and learn from previous experience to improve the quality of the communication. However, CR requires a flexible and adaptive physical layer in order to perform the required tasks efficiently. In this article, CR systems and their requirement of a physical layer are discussed, and the orthogonal frequency division multiplexing technique is investigated as a candidate transmission technology for CR. The challenges that arise from employing OFDM in CR systems are identified. The cognitive properties of some OFDM-based wireless standards also are discussed to indicate the trend toward a more cognitive radio.     

Network issues for wireless communications

This article specifically focuses on wireless personal communications, i.e., wireless access, that provides either terminal or personal mobility. In particular, we discuss some important issues in networking, traffic, and performance. Although within radio and networking aspects there are significant commonalities between traditional cellular mobile communications and wireless personal communications, there exist distinct differences due to radio propagation and fading effects, interference environment, smaller cell sizes, type and pattern of mobility, and call delivery. Indeed, with respect to networking issues, a large set of system choices, characteristics of traffic to be carried, and important parameters have to be considered. These include the problems involved in selecting an appropriate multiaccess technology to efficiently handle the required subscriber service profile across a multiplicity of systems to complete a call. To present a meaningful discussion of these issues, we address in some detail radio resource assignment, mobility management, call control, and traffic aspect, which have significant impact on the network performance     

An improved mechanism for multiple MBMS sessions assignment in B3G cellular networks

In Universal Mobile Telecommunication System (UMTS), the downlink capacity is limited by the base station transmission power. Therefore, power control plays an important role to minimize the transmitted power shared among unicast and multicast users within a cell. In Multimedia Broadcast/Multicast Service (MBMS), power control targets to the efficient utilization of radio and network resources. However, the expected high demand for such services stresses the need for an efficient scheme, capable of dynamically allocating radio resources to parallel MBMS sessions. This paper proposes a power control mechanism for efficient MBMS session assignment in next generation UMTS networks. The mechanism shares efficiently the available power resources of UMTS base stations to MBMS sessions running in the network. Furthermore, the mechanism is evaluated through several realistic scenarios and the results indicate the ability of the mechanism to utilize efficiently the radio resources and to ensure the service continuity when parallel MBMS services run in the network. Our approach is compared with current 3rd Generation Partnership Project (3GPP) approaches, such as these presented in TS 25.346 and in TR 25.922, in order to highlight the enhancements that it provides.     

电离层电急流的人工调制

由基本的磁离子理论出发,构造了大功率电波调制电离层电急流的自洽理论模型.利用此模型,计算了电离层D/E区高度上电子温度随加热时间的变化,以及不同高度上的加热时间和冷却时间.基于方波脉冲的入射方式,详细地研究了加热区电离层电导率和赤道电急流的振荡过程.计算结果表明,地面入射的大功率电波能有效地调制电离层中存在的大尺度直流电流,而且该调制电流可以作为ELF/VLF电波的辐射源.最后简单地分析了在未来实际工程应用中所需要解决的问题.     

基于试验设计（DOE）方法的无线网络参数设置

在无线网络优化中,我们采用试验设计（DOE）的方法优化无线参数,在性能优化以及节能领域均取得良好效果,DOE方法比传统参数优化方法更适用于复杂的组合参数调整,不但效率高同时能够更准确,并可以广泛应用于TD／GSM提升网络性能的研究。     

A Novel Approach for the Link Layer in Impulse-based UWB Ad Hoc Networks

Ultra Wide Band (UWB) impulse radio, promises to be suitable for short-range, low-power, low cost and high data rate applications. While most UWB research is concentrating on the physical layer, little research has been published on the link layer. The fundamental operations in the link layer need to take into account the specifics of impulse radio and also the particular features of ad hoc networks. A novel self-organizing link layer protocol based on time hopping impulse radio, called SDD, was proposed by the authors. This protocol is a collision-free mechanism that enables the devices to discover neighboring nodes and arrange the access to communication resources shared among the nodes. In this paper, some issues related to the self-organizing link layer based on UWB impulse radio are investigated and addressed. The SDD protocol is further developed and specified in detail. The simulations are carried out using GloMoSim simulation environment. An SDD module has been developed and embedded in the simulator. Results show that the SDD protocol can work properly and efficiently in a single-hop ad hoc network.