基于ZigBee技术的XBee Pro模块在智能公交系统中的应用

以MaxStream公司推出Freescale MC1319x芯片组为核心。介绍了一种基于ZigBee协议的智能公交系统的XBee Pro RF模块设计方法。该模块满足IEEE802．15．4标准，可工作在2．4GHz的国际免费频段，并具有DSSS（直接序列扩频）功能。本系统的硬件采用标准UART接口，并具有接收、发送、睡眠、命令和空模式等5种操作模式。     

基于XBee模块的多接口ZigBee协议转换器

提出了一种基于XBee模块的多接口ZigBee协议转换器,给出了系统的软硬件设计方案。XBee模块作为一款内置了ZigBee协议的无线通信模块,在兼具ZigBee基本优势的情况下更是在功耗、成本方面有较明显的优势。基于这种模块的多接口协议转换器工作在2.4GHz ISM频段,遵循IEEE 802.15.4/ZigBee协议。转换器不仅成本低、体积小,实测结果也表明,它能够在250kbps的最高通信速率下完成稳定的数据传输。     

基于802.15.4/ZigBee无线传感器网络节点的物理层设计

无线传感网络和ZigBee都是目前研究的热门对象.本文简要介绍了基于IEEE 802.15.4/ZigBee的无线传感网络的主要优势,重点介绍了基于IEEE 802.15.4/ZigBee的传感器节点模型以及可供选择的几款传输模块芯片,并给出了一个实际的节点设计方案.     

基于ZigBee与XBee的智能家居系统设计及其性能测试

设计了一个以ARM与单片机为控制核心,以语音为控制信号,基于ZigBee与XBee两种无线通信技术的室内智能家居控制器的性能比较系统。并对系统在这两种通信方式下的通信距离、功耗以及抗干扰性进行了实验测试与数据对比分析。经实验分析结果表明,XBee无线通信技术通信距离更远,功耗更低,抗干扰性更强。     

IEEE802.15.4MAC协议CSMA/CA优化算法研究

IEEE802.15.4作为无线局域网的MAC层规范,它适用在低速率、低功耗和低成本的短距离通信的设备中。CSMA/CA协议是无线自组织网络中的基本协议,本文引入了一个新退避算法对CSMA/CA进行改进。改进后的结果表明,结点可以根据自身的流量动态地调整竞争窗口,从而有效地避免了访问冲突,提高了网络的吞吐量,进而也降低了设备的功耗。     

基于ZigBee协议和CDMA网络的电信机房监控系统

为实现对电信机房的实时监控,解决机房设备位置的调整带来的重新布线等问题,设计新的监控系统,利用Zigbee无线协议代替现有的有线通信模式。系统以计算机、ZigBee无线技术和CDMA（码分多址）通信模块为基础进行设计,通过引入多种传感器,实现对机房设备的远程无线连接控制,通过CDMA短信向受理人员发出监控报警信息。在实...     

IEEE802.15.4协议的性能分析与仿真

IEEE 802.15.4是一个自组织的无线网络标准,其中制定了PHY层和MAC层规范,主要应用场合为低成本、低功耗、低复杂度的无线个域网.许多参数在IEEE 802.15.4标准中仅给出取值范围而并未给出确定的值,虽然这些值对系统性能有着较为显著的影响.个域网中的设备大量采用电池供电,因此实现更低的能量消耗是该网络标...     

爱特梅尔推出ZigBee应用的800/900 MHz IEEE802.15.4兼容收发器

爱特梅尔公司(Atmel)宣布推出AT86RF212 800/900 MHz IEEE802.15.4 RF收发器,适用于包括ZigBee在内的低功耗无线应用。AT86RF212具有业界最佳的RF性能,在欧洲采用的800MHz和北美采用的900 MHz ISM频带内提供高达120dB的链路预算,获得这预算是因为该器件的灵敏度达-110dBm及最大输出功率为+10dBm。     

一种基于ZigBee协议的DSDV改进型路由算法

大量的研究人员也投入精力研究和改进无线传感网。其中,ZigBee协议在无线传感网中扮演着举足轻重的角色,其可使大量传感器高效互连的能力,是有线网络所不能及的。提出了一种基于ZigBee协议DSDV路由算法的改进型路由算法,根据仿真,改进后的算法在处理存在移动节点通信时有一定的优势。     

一种LEACH协议的改进方法

针对无线传感网络中如何有效平衡节点的能量分布,文中在LEACH协议的基础上,提出了一种改进方法,在选取簇头时,考虑簇头在监测区域的平均分布,判断簇头间的距离,大于某一阈值,则确定簇头选取成功。同时将改进后的协议与原LEACH协议进行仿真比较,结果表明,改进后的协议可更有效地进行能量平衡,且到达了延长网络寿命的目的。     

Distributed Borrowing Addressing Scheme for ZigBee/IEEE 802.15.4 Wireless Sensor Networks

This paper proposes a distributed borrowing addressing (DIBA) scheme to solve problems of failure in address assignments resulting from limited tree depth and width when the distributed address assignment mechanism is used in a ZigBee/IEEE 802.15.4 wireless sensor network. DIBA is a method of borrowing addresses from neighbor nodes for newly entering nodes and assigning the borrowed addresses. Its network or sensing coverage can increase with almost the same overhead as the existing method. DIBA is a simple and lightweight means of addressing and routing, making it suitable for wireless sensor networks. Simulations showed that DIBA is a distributed addressing scheme with consistently excellent performance.     

Hybrid Distributed Stochastic Addressing Scheme for ZigBee/IEEE 802.15.4 Wireless Sensor Networks

This paper proposes hybrid distributed stochastic addressing (HDSA), which combines the advantages of distributed addressing and stochastic addressing, to solve the problems encountered when constructing a network in a ZigBee‐based wireless sensor network. HDSA can assign all the addresses for ZigBee beyond the limit of addresses assigned by the existing distributed address assignment mechanism. Thus, it can make the network scalable and can also utilize the advantages of tree routing. The simulation results reveal that HDSA has better addressing performance than distributed addressing and better routing performance than other on‐demand routing methods.     

Optimal designs for IEEE 802.15.4 wireless sensor networks

This paper investigates the maximum achievable channel throughput in a single‐channel and single‐hop wireless sensor network using IEEE 802.15.4 Medium Access Control (MAC) protocol. We introduce a simple mean‐field approach to model the Carrier Sense Multiple Access with Collision Avoidance mechanism of the 802.15.4 MAC protocol under unsaturated conditions. We derive a set of expressions such as optimal sensing rate of a sensor node, its corresponding failure probability, and the channel throughput for both saturated and unsaturated networks. With those expressions, we propose several network designs to achieve the optimal throughput by choosing the appropriate MAC parameters. We validate the proposed optimal designs using ns‐2 simulations. Furthermore, we evaluate the network lifetime expectancy of the optimal designs and compare it with the lifetime of network settings under saturated conditions that use the default MAC parameters of IEEE 802.15.4. Copyright © 2011 John Wiley & Sons, Ltd.     

Integration of an IEEE 802.15.4 RFID network with mobile readers with a 802.11 WLAN

In this paper, we propose a coexistence scheme that allows radio‐frequency identification readers or sinks to collect data from radio‐frequency identification tags or sensors that use IEEE 802.15.4 wireless personal area network standard and send it to the access point via an IEEE 802.11 wireless local area network. The proposed scheme uses time scheduling and bridging via readers to allow for simultaneous operation of heterogeneous wireless networks that operate in the industrial, scientific, and medical frequency band at 2.4 GHz. A simple sleep management approach is developed that allows tags to reduce their power consumption as well as collision rate. To provide timely reaction to sudden changes in tag population or reader availability, we devise a scheme where the scheduling parameters are adjustable and readers are mobile. We evaluate the performance of our solution in four scenarios and confirm the flexibility of the proposed approach. Copyright © 2012 John Wiley & Sons, Ltd.     

On the Use of IEEE Std. 802.15.4 to Enable Wireless Sensor Networks in Building Automation

IEEE 802.15.4 is a new standard that addresses the need of low-rate wireless personal area networks or LR-WPAN with a focus on enabling pervasive wireless sensor networks for residential, commercial and industrial applications. The standard is characterized by maintaining a high level of simplicity, allowing for low cost and low power implementations. This paper presents a brief technical introduction of the IEEE 802.15.4 standard and analyzes its applicability for building automation applications.

移动Sink传感网中基于IEEE 802.15.4的拓扑控制与路由

针对查询驱动的移动Sink无线传感器网络,基于IEEE 802.15.4标准,提出了一个联合簇树组网和移动路由的跨层协议设计方案。以能耗、网络连通度、负载均衡和子树深度等指标为评价因子,在多目标优化模型下定义了一个拓扑综合评价函数,构建稳定的最优簇树网络结构;改进了IEEE 802.15.4 MAC中基于信标帧调度的分布式睡眠同步算法,维护较低占空比下的网络同步与拓扑修正;利用拓扑形成过程中依"最早信标帧"、"最好链路"、"最小层次"3种准则确立的父子关系,建立移动Sink与N-Hop范围内节点的双向路由路径。最终将上述MAC层的拓扑控制方案与网络层的查询路由方法完整实现于TinyOS协议栈中。实验结果表明,评价函数能够有效地反映组网质量,N-Hop后验式路由结合睡眠同步机制,在"最好链路"拓扑下表现出较高的能量效率。     

Performance evaluation of IEEE 802.15.4 sensor networks in industrial applications

Wireless sensor networks have been widely applied in industrial applications especially since the release of IEEE 802.15.4 standard. By participating in an automobile project in which an IEEE 802.15.4 based sensor and actuator network is deployed to measure and control the vibrations of an automotive system, we need to study many metrics of IEEE 802.15.4 sensor networks (e.g., packet delivery rate, latency, and energy consumption) under various sampling rates. In order to provide detailed modeling of hardware and software as well as network behaviors on each sensor node, we conduct plenty of experiments on a SystemC‐based wireless sensor networks simulator IDEA1, which supports the hardware and software co‐simulation of sensor nodes with certain flexibility of abstraction level. Compared with the existing works on performance evaluation of IEEE 802.15.4 protocols, the main contributions of this paper are the comprehensive studies of both beacon‐enabled and nonbeacon‐enabled modes under various parameter settings and the beacon tracking synchronization mechanism in the IEEE 802.15.4 standard, which is ignored in most previous works. Additionally, the in‐depth analysis of simulation results enables us to find the best parameter configurations to different traffic loads and application requirements, which can be used as general experiences for other applications.Copyright © 2014 John Wiley & Sons, Ltd.     

基于IEEE 802.15.4的无线传感器网络的设计与实现

利用基于IEEE 802.15.4的IP-Link1200模块,设计并实现了能够实时接入现有蜂窝网络的无线传感器网络的验证系统。该方案工作于900 MHz或1 800 MHz的GSM(全球移动通信系统)网络的SMS(短消息业务)平台,把从目标区域采集到的温湿度参数传送给位于远程的任务管理中心。用户只需用普通的支持短消息的手机,向任务管理中心发送固定格式的短消息,就可以实时地获得任意一指定节点的温湿度参数。另外,也可以通过Internet打印历史报表。     

Performance evaluation of an IEEE 802.15.4 sensor network with a star topology

One class of applications envisaged for the IEEE 802.15.4 LR-WPAN (low data rate—wireless personal area network) standard is wireless sensor networks for monitoring and control applications. In this paper we provide an analytical performance model for a network in which the sensors are at the tips of a star topology, and the sensors need to transmit their measurements to the hub node so that certain objectives for packet delay and packet discard are met. We first carry out a saturation throughput analysis of the system; i.e., it is assumed that each sensor has an infinite backlog of packets and the throughput of the system is sought. After a careful analysis of the CSMA/CA MAC that is employed in the standard, and after making a certain decoupling approximation, we identify an embedded Markov renewal process, whose analysis yields a fixed point equation, from whose solution the saturation throughput can be calculated. We validate our model against ns2 simulations (using an IEEE 802.15.4 module developed by Zheng [14]). We find that with the default back-off parameters the saturation throughput decreases sharply with increasing number of nodes. We use our analytical model to study the problem and we propose alternative back-off parameters that prevent the drop in throughput. We then show how the saturation analysis can be used to obtain an analytical model for the finite arrival rate case. This finite load model captures very well the qualitative behavior of the system, and also provides a good approximation to the packet discard probability, and the throughput. For the default parameters, the finite load throughput is found to first increase and then decrease with increasing load. We find that for typical performance objectives (mean delay and packet discard) the packet discard probability would constrain the system capacity. Finally, we show how to derive a node lifetime analysis using various rates and probabilities obtained from our performance analysis model.

A novel method for mitigating the effects of dynamic coexistence on the operation of IEEE 802.15.4‐based mobile WSNs

Wireless networks dynamically coexist when their transmission ranges overlap as a result of mobility. Mobile wireless sensor networks (WSNs) may suffer from significant degradation of performance due to the interference caused by dynamic coexistence, which is particularly critical for health monitoring WSNs. In this paper, we propose a novel method to detect and mitigate the harmful effects of dynamic coexistence on the operation of IEEE 802.15.4‐based mobile health monitoring WSNs. IEEE 802.15.4 uses the guaranteed time slots (GTS) mechanism to eliminate contention; however, successful transmissions cannot be guaranteed for coexisting WSNs. We show that using limited clear channel assessments at the beginning of the GTS enables the mobile WSNs to avoid collisions with minimum overhead. This method can also be used in combination with the previously proposed mechanisms for coexistence management. We analytically investigate the effects of using this method on the performance of the dynamically coexisting WSNs. We use OPNET simulation to investigate the coexistence of health monitoring WSNs and also to validate the proposed method. Our results indicate that using the proposed mechanism, 2–10 coexisting mobile WSNs with relatively high transmission rates (20–30% of maximum throughput) can achieve 20–90% higher rates of successful transmissions, with less than 10% increase in power consumption. Copyright © 2014 John Wiley & Sons, Ltd.