zigbeeieee802154網(wǎng)絡(luò)應(yīng)用實(shí)例畢業(yè)論文外文翻譯(文件)
【正文】 (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 batterypowered 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. ZigBeebased 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 ZigBeebased location methods. The basic concept of location estimation is shown in Figure , 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 bees 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. 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 active tags can cost more than passive ones, but the IEEE tags have extended range and can provide additional information such as animal heartbeat and the animal’s approximate location. Healthcare One of the applications of IEEE in the healthcare industry is monitoring a patient’s 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 work can be used to collect data from various sensors connected to the patient. The standard uses 128bit Advanced Encryption Standard (AES) technology to securely transfer data between ZigBee devices and other works. Figure 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 work and other works, such as an Inter Protocol (IP) work. The patient information is then transmitted over the Inter to a personal puter that the physician or nurse uses to monitor the patient. This system could help hospitals improve patient care and relieve hospital overcrowding by enabling th
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