共查询到20条相似文献,搜索用时 139 毫秒
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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. 相似文献
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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... 相似文献
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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. 相似文献
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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。 相似文献
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基于nRF905的智能照明控制系统 总被引:1,自引:0,他引:1
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. 相似文献
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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. 相似文献
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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. 相似文献
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认知无线电中基于干扰温度的频谱探测技术 总被引:3,自引:1,他引:2
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. 相似文献
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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. 相似文献
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Network issues for wireless communications 总被引:1,自引:0,他引:1
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 相似文献
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An improved mechanism for multiple MBMS sessions assignment in B3G cellular networks 总被引:1,自引:0,他引:1
Antonios Alexiou Christos Bouras Vasileios Kokkinos Evangelos Rekkas 《Wireless Networks》2010,16(3):671-686
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. 相似文献
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彭江龙 《电信工程技术与标准化》2012,25(1):16-21
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。 相似文献
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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. 相似文献