2.4GHz频段家庭电磁环境下蓝牙性能分析与实验

对工科医(ISM)频段的家庭电磁环境进行了分析与测量,给出了测试波型与数据.应用一个通用的同频段干扰模型,对蓝牙无线网络在此电磁环境下的性能进行了仿真.测试了蓝牙无线网络在无线局域网(WLAN)和微波炉干扰下的性能影响.实验结果表明:蓝牙无线网络在家庭电磁环境干扰下性能最高下降了42%,工作受到了严重影响.说明如今的家庭电磁环境十分恶劣,应给予足够的重视.     

浅论通信领域内的电磁兼容

0引言 随着科学技术的进步和发展,人们在日常生产生活中使用的电子、电气设备的种类越来越多,电子电气设备使用的频段越来越高,电子设备在运行的时候,往往产生一些人们不需要的电磁能量,这些能量通过辐射、传导的方式向外界传出来会影响其他设备或系统的工作.     

无线局域网与蓝牙之间干扰问题的研究

蓝牙(BT)和无线局域网(WLAN)均工作在2.4GHz的ISM频段,在相同环境下同时使用容易产生相互干扰。文章通过WLAN和BT设备间相互干扰机制的分析、数学模型的建立和实验,对两者之间的干扰进行了研究并提出了相应的解决措施。     

nRF903在ISM频段中通信协议的设计

本文在介绍无线收发芯片nEF903的基础上,对nRF903工作在ISM频段的通信协议进行了设计.本文提出的无线通信解决方案简单、可靠,可用于遥控、遥感、无线抄表、环境检测等领域.     

安全与电磁兼容领域的信息指南--<安全与电磁兼容>(光盘版)综述

随着电子产品、通信产品、计算机和电气设备的不断发展,它们在人们的工作和生活领域中日益占有重要地位,使用数量急剧增长.由于用电设备密集程度越来越高,造成了空间电磁环境的污染越来越严重.恶劣的电磁环境不仅对人类日益依赖的计算机、通信和各种电子系统具有灾难性的危害,而且对我们的健康及人身安全也会产生严重影响.     

特殊环境下无线通信系统的频率选择

在地下矿井和生产环境对通信频率影响的基础上,考虑到移动设备的体积,确定井下无线通信传输在工业、科学、医学(ISM)频段(868 MHz～915 MHz)较合理.这样也有利于与地面移动通信系统兼容以及利用现有的技术成果.另一个使用ISM频段的原因是考虑到该频段天线尺寸和设备体积远小于高、中、低频段的天线尺寸和设备体积.     

2.4 GHz频段家庭电磁环境的分析和测量

对2.4～2.5 GHz频段范围内家庭的电磁环境进行了分析,给出了单个家庭住宅和多个家庭住宅的典型应用场景图.利用频谱分析仪和喇叭天线对这一频段的电磁环境进行了测量,给出了测量数据和波形,并对测量结果进行了分析和比较.还通过用户调研和电磁环境测量,对这一环境内设备间的相互干扰,尤其是无绳电话与WLAN设备间的电磁干扰情况进行了分析,并给出了初步的解决建议.     

无线局域网在医疗场所电磁兼容性的改善

无线局域网(WLAN)随着技术的成熟和产品的降价逐步进入医疗领域。医院中最大的数据库是病人们的病历档案。为随时能够查询数据,建设一个无线局域网,医务人员只需带着一台笔记本电脑或PDA等设备,在每个病房都可以将病人的最新情况实时送回中央数据库,也可以随时从中央数据库获取信息。医务人员从一间病房到另一间病房,可以不受连线的限制,迅速、方便地交换重要数据,工作效率将大大提高。但在方便使用无线局域网时,无线局域网在医疗场所的电磁兼容性问题却不容忽视。可能产生电磁干扰的频段对于无线局域网所处的2.4GHz频段和ISM的工作频…     

复杂电磁环境下的机载电子设备安全性设计

复杂电磁环境下的机载电子设备安全性设计主要解决①电磁环境通过感应或耦合等方式可能造成机载电子设备工作混乱而导致安全性问题②在机载电子设备保持正常工作状态下,电磁环境通过感应或耦合等方式形成的感应电压或感应电流达到或超过机载电子设备相关性能指标引起"非正常动作"而导致的安全性问题。通过介绍一种典型机载电子设备在复杂电磁环境下的电磁安全性设计情况,表明机载电子设备开展电磁环境安全性设计的重要性和必要性。     

蓝牙无线通信技术与实践

无线通信技术得到了显著发展,蓝牙技术是一种可靠的无线接入方式,全球通用频段为2.5GHz ISM,在医疗、科学、生物技术以及工业领域得到了广泛应用,使用数字设备将不同频段连接起来,能构成一个完整的无线局域网。     

Interference modeling and performance of Bluetooth MAC protocol

The emergence of Bluetooth as a default radio interface has allowed handheld electronic devices to be instantly interconnected as ad hoc networks. These short-range ad hoc wireless networks, called piconets, operate in the unlicensed 2.4-GHz ISM (Industrial-Scientific-Medical) band where devices may be used to configure single or overlapping piconets, known as scatternet. As all piconets operate in the same frequency band, the presence of multiple piconets in the vicinity may create interference on signal reception. This paper employs a signal capture model to study the piconet MAC performance, taking inter-piconet interference into consideration. This model leads to several important mathematical relationships for Bluetooth networks, including successful packet transmission probability. Furthermore, our model and anticipated throughput are validated using extensive simulation. These results indicate that Bluetooth throughput is affected by multiple piconet interference. Definitely, our model can be considered to provide a solid foundation for future interference aware Bluetooth protocols.     

Networking gets personal

The Bluetooth wireless communication standard is much more than a convenient replacement for cables. With their capacity for autonomous interaction and rich functionality, Bluetooth devices will end the hassle in our gadget-laden lives. World-wide operation is supported by the use of the globally available unlicensed Industrial-Scientific-Medical (ISM) band (2-4 GHz), which Bluetooth shares with the 802.11b wireless LAN standard, or WiFi, and some tens of millions of microwave ovens. Interference risks are minimised by the use of a frequency-hopping spread-spectrum transmission scheme     

A new role-switching mechanism optimizing the coexistence of?bluetooth and Wi-Fi networks

Unlicensed ISM band is used by various wireless technologies. Therefore, issues related to ensuring the required efficiency and quality of operation of coexisting networks become essential. The paper addresses the problem of mutual interferences between IEEE 802.11b transmitters (commercially named Wi-Fi) and Bluetooth (BT) devices. An optimization approach to modeling the topology of BT scatternets is introduced, resulting in more efficient utilization of ISM environment consisting of BT and Wi-Fi networks. To achieve it, the Integer Linear Programming approach has been proposed. Example results presented in the paper illustrate significant benefits of using the proposed modeling strategy.     

基于2．4GHz／900MHz双射频蓝牙模块的研究与实现

提出了一种基于2.4GHz/900MHz双射频蓝牙模块的研究与实现方案。该方法通过双射频通信模式来解决短距离无线通信中日益严重的共扰问题,为之提出了全新的解决思路。在不改变蓝牙基带协议的基础上,增加蓝牙900MHz射频模块,使得蓝牙设备的射频部分可在2.4GHz或900MHz的ISM频段间切换。实验结果表明,对于双射频的蓝牙系统来说,其不仅改善了与其他无线通信方式的相互干扰问题,而且还从蓝牙通信距离方面得到了改进。     

Coexistence of 2.4 GHz sensor networks in home environment

The IEEE 802.15.4 is one of the low-layer communication standards for personal area networks(PANs) and wireless sensor networks(WSNs),which may be interfered by other wireless devices in the industrial,scientific and medical(ISM) frequency bands,especially in home environment,such as devices of IEEE 802.11b,Bluetooth,cordless telephone,and microwave oven radiation.This article examines the mutual interference effects of 2.4 GHz devices widely deployed at home,via both theoretical analysis and real-life expe...     

Channel Clustering and Probabilistic Channel Visiting Techniques for WLAN Interference Mitigation in Bluetooth Devices

Since Bluetooth and wireless local area network (WLAN) technologies both operate at the 2.4-GHz industrial, scientific, and medical (ISM) band, the two types of devices may suffer from mutual interference and performance degradations. In this paper, we propose two new techniques, channel clustering and probabilistic channel visiting, to effectively improve the existing coexistence and interference mitigation mechanisms. The channel clustering technique employs statistical pattern recognition to classify the status of Bluetooth channels more accurately. The probabilistic channel visiting is used to more equitably allocate the channel resources between Bluetooth and WLAN devices. The effectiveness of these techniques is quantified by simulations. Results show that both techniques are beneficial in improving the performance of the existing mechanisms.     

Mixed signals - ZigBee aims to be a standard for industrial low-power radio, but we might never see full compatibility between modules that support it

We are now - if the vendors involved are to be believed - living in the age of ZigBee. Like Bluetooth, it mainly operates in the licence-exempt industrial, scientific and medical (ISM) band around 2.4GHz. Unlike Bluetooth, which is predominantly used for wireless headsets, it is intended for short range data communications between `intelligent' devices. This puts in firmly in the industrial and commercial sector, as opposed to Bluetooth which now sits almost exclusively in the consumer space. The focus on industrial and not consumer applications means ZigBee faces a difficult challenge; it needs to offer the performance demanded by industrial and commercial applications, but with a competitively low price tag when compared to existing proprietary implementations - both wired and wireless - in a highly fragmented marketplace     

Future Applications of Bluetooth

Bluetooth is a short-range radio technology that is increasingly being provided in the various electronic devices that we carry around, such as laptops, mobile telephones and cameras. Bluetooth's supporters claim that it can deliver 'unprecedented productivity' through the seamless interconnection of these devices into a personal area network (PAN) — but does the technology really live up to this expectation? This paper investigates the claims surrounding Bluetooth, and compares its capabilities and potential applications with the existing technologies of DECT and wireless LAN. Bluetooth usage scenarios are considered in the areas of ad hoc networks, the home, the office environment, mCommerce and public access wireless hot-spots. Widespread implementation in devices does not mean widespread usage, and barriers to easy operation are examined to see if Bluetooth can move beyond its personal area network role into new areas of networking that could benefit a broad range of users.     

Interference Evaluation of Bluetooth and IEEE 802.11b Systems

The emergence of several radio technologies, such as Bluetooth and IEEE 802.11, operating in the 2.4 GHz unlicensed ISM frequency band, may lead to signal interference and result in significant performance degradation when devices are colocated in the same environment. The main goal of this paper is to evaluate the effect of mutual interference on the performance of Bluetooth and IEEE 802.11b systems. We develop a simulation framework for modeling interference based on detailed MAC and PHY models. First, we use a simple simulation scenario to highlight the effects of parameters, such as transmission power, offered load, and traffic type. We then turn to more complex scenarios involving multiple Bluetooth piconets and WLAN devices.     

Coexistence of IEEE 802.11b and Bluetooth: An Integrated Performance Analysis

IEEE 802.11b wireless networks and Bluetooth networks provide complimentary services using the same unlicensed radio frequency band. As the benefits of utilizing these services become increasingly apparent, the likelihood of mutual interference also increases. The well-known frequency hopping algorithm and adaptive frequency hopping algorithm do not fully consider the interference level of the operating environment. In this paper an algorithm called interference-aware adaptive frequency hopping (IAFH) is presented and implemented on Bluetooth devices to mitigate the interference between IEEE 802.11b and Bluetooth wireless networks. An analytical model of IAFH is developed to evaluate the performance of 802.11b stations and Bluetooth devices in a mutual interference environment. The analysis comprises the collision probability, packet error rate, and throughput performance for both IEEE 802.11b and Bluetooth wireless networks. Simulation results confirm that 802.11b station and IAFH-enabled Bluetooth devices experience lower packet error rates and better throughput as compared to the frequency hopping and adaptive frequency hopping algorithms.