ZigBeeIEEE802.15.4网络应用实例毕业论文外文翻译

中文 3480 字 英文资料翻译 ZigBee/IEEE 802.15.4 Networking Examples ZigBee networking has a diverse range of applications, including but not limited to home automation, inventory tracking, and healthcare. This chapter reviews a number of the application scenarios in which ZigBee devices can increase efficiency and/or reduce cost. Full ZigBee protocol implementation has the advantage of reliable mesh networking capability. However, if the application is simple, it might be possible to implement only IEEE 802.15.4 layers. 2.1 Home Automation Home automation is one of the major application areas for ZigBee wireless networking. In this section, a number of these use cases are reviewed. The typical data rate in home automation is only 10Kbps. Figure 2.1 shows some of the possible ZigBee applications in a typical residential building. Most of the applications shown in Figure 2.1 are briefly reviewed in this chapter. 2.1.1 Security Systems A security system can consist of several sensors, including motion detectors, glass-break sensors, and security cameras. These devices need to communicate with the central security panel through either wire or a wireless network. ZigBee-based security systems simplify installing and upgrading security systems. Despite ZigBees low data rate, it is still possible to transfer images wirelessly with acceptable quality. For example, ZigBee has been used in a wireless camera system that records videos of visitors at a homes front door and transmits them to a dedicated monitor inside the house. 2.1.2 Meter-Reading Systems Utility meters need to be read on a regular basis to generate utility bills. One way to do so is to read the meters manually at homeowners premises and enter the values into a database. A ZigBee-based automatic meter-reading (AMR) system can create self-forming wireless mesh networks across residential complexes that link meters with utilities corporate offices. AMR provides the opportunity to remotely monitor a residences electric, gas, and water usage and eliminate the need for a human visiting each residential unit on a monthly basis. An AMR can do more than simply deliver the total monthly usage data; it can gather detailed usage information, automatically detect leaks and equipment problems, and help in tamper detection. ZigBee-based wireless devices not only perform monitoring tasks, they can manage the usage peak by communicating with the appliances inside the house. For example, when there is a surge in electricity usage, a ZigBee-enabled electric water heater can be turned off for a short period of time to reduce the peak power consumption. 2.1.3 Irrigation Systems A sensor-based irrigation system can result in efficient water management. Sensors across the landscaping field can communicate to the irrigation panel the soil moisture level at different depths. The controller determines the watering time based on moisture level, plant type, time of day, and the season. A distributed wireless sensor network eliminates the difficulty of wiring sensor stations across the field and reduces the maintenance cost. 2.1.4 Light Control Systems Light control is one of the classic examples of using ZigBee in a house or commercial building. In traditional light installation, to turn on or off the light it is necessary to bring the wire from the light to a switch. Installation of a new recess light, for example, requires new wiring to a switch. If the recess light and the switch are equipped with ZigBee devices, no wired connection between the light and the switch is necessary. In this way, any switch in the house can be assigned to turn on and off a specific light. Figure 2.2 is an example of wireless connections between wall switches and lights. In our example, the lights are located in a residential building entrance, living area, and hallway. The wall switch in the entrance can turn on and off any of the four lights. The living area wall switch, in contrast, communicates only with the lights in the living area. Living area lights are in close proximity to each other, and therefore a single ZigBee device can be used for both lights. The concept of using binding tables (see Section 1.12) is applicable in the example of Figure 2.2. Wall switch 1 is logically connected to all four lights. Wall switch 2 is bound only to the lights in the living area. One of the devices in the network has the task of storing and updating the binding table. A ZigBee-enabled recess light can be more expensive than a regular recess light, but the installation cost of a ZigBee-enabled light is lower because it requires no additional wiring to a wall switch. Using wireless remotes to control the lights is not a new concept. ZigBee provides the opportunity to implement this concept on a large scale by ensuring long battery life and interoperability of products from various vendors in a reliable and low-cost network. In addition to potential cost savings, ZigBee-enabled lights can have other benefits in a house. For example, the ZigBee devices embedded in the recess lights can act as routers to relay a message across the house, or the lights can be programmed to dim whenever the television set is turned on. The ZigBee light control mechanism has been used for street light controls as well. 2.1.5 Multizone HVAC Systems The multizone control system allows a single heating, ventilation, and air-conditioning (HVAC) unit to have separate temperature zones in the house. Zoning the HVAC system can help save energy by controlling the flow of air to each room and avoiding cooling or heating unnecessary areas. Figure 2.3 is a simplified diagram that shows motors controlling air dampers and regulating the flow of air to different zones. ZigBee devices control these motors based on the commands they receive from the main HVAC zone control panel and temperature sensors. An alternative way of implementing a multizone control system is to connect the zone control panel, motors, and temperature sensors via wires instead of a wireless network. A wired system has less flexibility and additional labor cost for wiring, but the cost of the parts might be slightly lower. Total system cost and flexibility for future modifications should be the decision factors in selecting between these two implementation methods. 2.2 Consumer Electronics: Remote Control In consumer electronics, ZigBee can be used in wireless remote controls, game controllers, a wireless mouse for a personal computer, and many other applications. In this section, we briefly review the application of ZigBee in wireless remotes. An infrared (IR) remote controller communicates with televisions, DVDs, and other entertainment devices via infrared signals. The limitation of IR remotes is that they provide only one-way communication from the remote to the entertainment device. Also, IR signals do not penetrate walls and other objects and therefore require line of sight to operate properly. Radio frequency (RF) signals, however, easily penetrate walls and most objects. IEEE 802.15.4 is a proper replacement for IR technology in remote controls because of the low cost and long battery life of ZigBee-based wireless communication. IEEE 802.15.4 can be used to create two-way communications between the remote control and the entertainment device. For example, song information or on-screen programming options can be downloaded in to the remote itself, even when the remote control is not in the same room as the entertainment device. 2.3 Industrial Automation At the industrial level, ZigBee mesh networking can help in areas such as energy management, light control, process control, and asset management. In this section, application of ZigBee in asset management and personnel tracking is briefly reviewed. Asset Management and Personnel Tracking Passive radio frequency identification (RFID) tags have been in use for several years. Although a passive RFID tag does not have any battery, the RFID reader unit can be a battery-powered instrument. A passive RFID tag can transmit only simple information such as an ID number, which is sufficient for many asset management applications. Active RFIDs, such as ZigBee devices, are battery powered and generally are more expensive than passive RFIDs. ZigBee-based active RFIDs have longer range than passive RFIDs and can provide additional services such as estimating the location of assets or personnel. Chapter 7 covers the details of ZigBee-based location methods. The basic concept of location estimation is shown in Figure 2.4, where location of personnel is tracked inside a typical office building with offices and cubes. There are three fixed ZigBee nodes with known locations. The mobile ZigBee node, carried by an employee, broadcasts a signal that is received by all three fixed nodes. The signal becomes weaker as it travels longer; therefore, the amplitude of the signal received by each of the fixed nodes can be different. There are several algorithms that can take the received signal strength at the three fixed nodes and calculate the approximate location of the mobile node. The signal transmitted from the mobile node is reflected from walls and other objects in the room before it reaches the fixed nodes, which results in reduced accuracy of the location estimation. Chapter 7 reviews some of the methods developed to improve the location estimation accuracy. 2.3.2 Livestock Tracking Livestock are vulnerable to disease, and it is important to track and identify a diseased animal quickly. Rapid disease response reduces the number of producers impacted by a disease outbreak or other animal health events 6 . Passive RFID tags have been used as an inexpensive solution for livestock tracking and can be sufficient for some applications. Passive RFID tags have limited range and can only provide previously stored information such as an identification number. IEEE 802.15.4-based active tags can cost more than passive ones, but the IEEE 802.15.4 tags have extended range and can provide additional information such as animal heartbeat and the animals approximate location. 2.4 Healthcare One of the applications of IEEE 802.15.4 in the healthcare industry is monitoring a patients vital information remotely. Consider a patient who is staying at his home but for whom it is important that his physician monitor his heart rate and blood pressure continuously. In this system, an IEEE 802.15.4 network can be used to collect data from various sensors connected to the patient. The 802.15.4 standard uses 128-bit Advanced Encryption Standard (AES) technology to securely transfer data between ZigBee devices and other networks. Figure 2.5 is a simplified diagram of a remote monitoring system. A patient wears a ZigBee device that interfaces with a sensor, such as a blood pressure sensor, that gathers the information on a periodic basis. Then this information is transmitted to a ZigBee gateway. A ZigBee gateway provides the interface between a ZigBee network and other networks, such as an Internet Protocol (IP) network. The patient information is then transmitted over the Internet to a personal computer that the physician or nurse uses to monitor the patient. This system could help hospitals improve patient care and relieve hospital overcrowding by enabling them to monitor patients at home. 2.5 Other Applications 2.5.1 Hotel Guest Room Access ZigBee-based systems can replace the magnetic key card systems used in hotels to access guest rooms. The traditional room access plastic cards have a magnetic strip on their back; the card reader installed on the guest door reads the information encoded into the magnetic strip to allow or deny access to the room. Installing this reader for each door requires wiring through the door. Alternatively, a ZigBee- based room access system includes a portable ZigBee device that acts as the key and a battery-powered ZigBee device inside the door that locks and unlocks it. Unlike the traditional method, the ZigBee-based room access system does not require wiring each door, which reduces the installation cost. 2.5.2 Fire Extinguishers Fire extinguishers should be checked every 30 days to make sure all the canisters are charged and pressures are correct. Instead of checking the extinguishers manually, in a ZigBee-based monitoring system a sensor is attached to each extinguisher to monitor its status and wirelessly communicate with the coordinator when maintenance is needed. A ZigBee-based monitoring system not only saves time and labor cost, it also helps improve fire safety by immediately alerting authorities if a fire extinguisher is not working properly. ZigBee/IEEE 802.15.4 网络应用实例 ZigBee 非常广泛的应用，包括智能家居、库存跟踪和医疗保健，但又不仅限于此。 本章 回顾了 许多可以 运用 ZigBee设备提高效率和降低成本 的应用实例 。完整的 ZigBee 协议 具备 可靠的 网状 网络 性能的优点 。然而 ， 如果应用 很简单 ，也 可能 仅使用 IEEE 802.15.4层。 1.1 智能家居 智能家居 是 ZigBee 无线网络 的 一个主要应用领域 。 在本节中 ， 回顾 了 大量这样的 用例 。 在 智能家居 中 典型的数据率只有 10 Kbps。 图 1.1展示 了在一个典型的住宅建筑 中的 一些 可行 的 ZigBee 应用 。 在 本 章 中对 图 1.1 中 展 示 的 大多数应用 作了简要 介绍 。 1.1.1 安全系统 一个安全系统可以由多个传感器 组成 ， 包括运动探测器、玻璃破碎传感器和安全 摄像头。这些设备需要通过 有 线或无线网络与 中央 安全 面板通讯 。 基于ZigBee的 安全系统 简化了安全系统的 安装和 更新过程 。尽管 ZigBee的数据率 很低 ，但 它 仍然 可以 无线传输 质量 可接受的 图像。例如 ， ZigBee 已被应用于 一个录制门外访客 视频传送到 住宅 里 一个专用 监控 器的 无线摄像系统 。 图 1.1 可能 启用 ZigBee 设备 的 典型居住建筑 1.1.2 抄表系统 电表需要定期 读取数据 生成水电费 账单 。 一种 方法是手动 读 取 房主 房屋前 的电表数值，然后 输入到一个数据库。 一个基于 ZigBee的 自动抄表 系统 （ AMR）可以 自发 创建 一个连接 住宅区 电表 与 电表 公司办公室的无线网状网络。 AMR 通过 远程监控住宅的电力、煤气和水的使用 的机会，并且淘汰了人力每月挨家挨户去查电表的方式。 AMR 的 作用 不仅仅是 传输每月水电 使用量数据 ； 它 还 可以收集 详细的使用信息 ， 自动检测泄漏和设备问题 ，协助入侵检测 。基于 ZigBee 的 无线设备不仅执行监控 任务 ， 他们 还 可以 通过和室内的装置通信来管理使用高峰期 。例如 ， 当用电量激增 时， 可以关闭 ZigBee电 热水器一段时间来 降低 高峰期用电量 。 1.1.3 灌溉系统 一个 基于 传感器 的 灌溉系统能 使 水资源管理 更有效率 。 田野里的传感器能够把不同深度土壤的湿润程度传给灌溉面板。控制器根据土壤的湿度，植物种类，一天中的时间和季节等情况来确定灌溉时间。 分布式无线传感器网络消除了 在田野中建立有线传感器基站的困难， 降低 了 维修成本。 1.1.4 灯控系统 灯 光控制是 在室内或商业建筑中使用 ZigBee 的一个典型例子。 在传统的照明装置 中，必须从电灯到开关扯一根电线 来开启或关闭 电 灯。 例如，安装一个新壁灯的时候，需要一条新的到开关的电线。如果壁灯和开关都配备了 ZigBee 设备的话，那么电灯和开关之间将不再需要电线连接。这样，室内的任何开关都可以被指派来打开和关闭一盏特定的电灯。 图 1.2 是一个墙上开关和电灯间无线连接的例子 。在我们的示例中 , 电灯位于居民建筑的入口处，居住区和走廊。 在入口处的墙壁开关可以打开或关闭任何四个灯。相反 , 居住区墙上的开关仅与位于居住区的电灯进行通信 。 居住区的电灯彼此挨得很近，因此一个 ZigBee设备就能够控制这两个灯。 使用绑定表的概念也适应于图 1.2的例子。墙上开关 1逻辑上与所有的 4盏灯相连，开关 2只与居住区的电灯绑定，网络的其中一个设备负 责存储和更新绑定表。 一个 支持 ZigBee 的壁灯要比常规的壁灯更贵，但是它的安装费用却较低，因为它不需要额外的电线连接到墙上的开关。使用无线来遥控电灯已经不是一个新的概念，通过确保较长的电池寿命和来自不同经销商的产品的互操作性，ZigBee提供了在可靠的，低成本的网络中大范围实现这个概念的机会。 除了潜在的成本节省外，在室内， ZigBee 电灯还有其他的好处。例如，嵌入到壁灯内的 ZigBee 设备可以充当路由器，在房间内转发信息，或者，壁灯可以被编程设计为当电视打开时变暗。 ZigBee 灯控机制同样也已经被用于路 灯控制。 图 1.2 住宅建筑 中的 ZigBee 无线网络光控 系统 1.1.5 多层 供暖 系统 在多层的控制系统允许 单个的供暖，通风和空调单元在室内有各自的温度区域 。 HVAC分区系统通过控制每个房间的空气流动可以帮助节省能源，避免对不必要的区域进行冷却或加热。图 1.3是一个简化的图表，它显示了发动机控制空气湿度和管理不同房间的空气流动。 ZigBee 设备根据它们从主 HVAC 区域控制面板和温度传感器接收到的命令来控制这些发动机。另一种使用多区域控制系统的方法是通过有线而非无线网络的方式来连接区域控制面板，发动机和温度传感器。无线系统有较低的复杂度和额外的布线成本，但是这部分的成本可能会稍微低一些。总共的系统花费和将来的更新复杂度是在这两种应用方法间进行选择的决定因素。 . 图 1.3 采用 ZigBee 空气阻尼器 的 多层空调 1.2 消费电子 ： 远程控制 在消费电子中， ZigBee 可以被用在远程无线控制，游戏控制器，个人电脑的无线鼠标和许多其他应用中 。在这部分中，我们简单的介绍了 ZigBee 在远程无线控制中的应用。 红外（ IR）远程控制器通过红外信号与电视， DVD 和其他娱乐设备进行通信，红外遥控的限制就是它们只提供从遥控端到娱乐设备的单方向通信。此外，红外信号不能穿透墙壁和其他物体，因此需要对红外线进行适当操作。然而，射频信号可以很轻易的穿透大部分物体。 在远程控制方面， IEEE 802.15.4是对 IR 技术的一个合适的替代，因为基于ZigBee的无线通信具有低成本和较长的电池寿命的优点。 IEEE 802.15.4能够在远程控制和娱乐设备间建立双向的通 信。例如，歌曲信息和在屏幕编程选项能够被下载到遥控器本身，即使被远程控制的娱乐设备与遥控器不是在同一个房间。 1.3 工业自动化 在工业级水平上， ZigBee 网状网络可以用于能源管理，照明控制，过程