基于无线传感器网络的智能交通信号控制外文翻译(编辑修改稿)

基于无线传感器网络的智能交通信号控制外文翻译(编辑修改稿)内容摘要：

in bination with this type of mote. Tmote Sky features the Chipcon CC2420 radio for wireless munications. The CC2420 is an IEEE pliant radio providing the PHY and some MAC functions [5]. With sensitivity exceeding the IEEE specification and low power operation, the CC2420 provides reliable wireless munication. The CC2420 is highly configurable for many applications with the default radio settings providing IEEE pliance. ZigBee specifications can be implemented using the builtin wireless transmitter in the Tmote Sky. Fig. 3 Tmote Sky H. Tmote Key Features • 250kbps IEEE Chipcon Wireless Transceiver • Interoperability with other IEEE devices. • 8MHz Texas Instruments MSP430 microcontroller (10k RAM, 48k Flash Memory) • Integrated ADC, DAC, Supply Voltage Supervisor, and DMA Controller • Integrated onboard antenna with 50m range indoors / 125m range outdoors • Integrated Humidity, Temperature, and Light sensors • Ultra low current consumption • Fast wakeup from sleep (6μs) • Hardware linklayer encryption and authentication • Programming and data collection via USB • 16pin expansion support and optional SMA antenna connector • TinyOS support : mesh working and munication implementation • Complies with FCC Part 15 and Industry Canada regulations • Environmentally friendly – plies with RoHS regulations [4]. I. ZigBee Wireless Technology ZigBee is a specification for a suite of high level munication protocols using small, lowpower digital radios based on an IEEE standard for personal area works [6] [7]. ZigBee devices are often used in mesh work form to transmit data over longer distances, passing data through intermediate devices to reach more distant allows ZigBee works to be formed adhoc, with no centralized control or highpower transmitter/receiver able to reach all of the devices. Any ZigBee device can be tasked with running the work. ZigBee is targeted at applications that require a low data rate, long battery life, and secure working. ZigBee has a defined rate of 250kbps, best suited for periodic or intermittent data or a single signal transmission from a sensor or input device. Applications include wireless light switches, electrical meters with inhomedisplays, traffic management systems, and other consumer and industrial equipment that requires shortrange wireless transfer of data at relatively low rates. The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth. J. Types of ZigBee Devices ZigBee devices are of three types:  ZigBee Coordinator (ZC): The most capable device, the Coordinator forms the root of the work tree and might bridge to other works. There is exactly one ZigBee Coordinator in each work since it is the device that started the work originally. It stores information about the work, including acting as the Trust Center amp。 repository for security keys. The ZigBee Coordinator the central controller is in this system.  ZigBee Router (ZR): In addition to running an application function, a device can act as an intermediate router, passing on data from other devices.  ZigBee End Device (ZED): It contains just enough functionality to talk to the parent node. It cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC. K. ZigBee Protocols The protocols build on recent algorithmic research to automatically construct a lowspeed adhoc work of nodes. In most large work instances, the work will be a cluster of clusters. It can also form a mesh or a single cluster. The current ZigBee protocols support beacon and nonbeacon enabled works. In nonbeaconenabled works, an unslotted CSMA/CA channel access mechanism is used. In this type of work, ZigBee Routers typically have their receivers continuously active, requiring a more robust power supply. However, this allows for heterogeneous works in which some devices receive continuously, while others only transmit when an external stimulus is detected. In beaconenabled works, the special work nodes called ZigBee Routers transmit periodic beacons to confirm their presence to other work nodes. Nodes may sleep between beacons, thus lowering their duty cycle and extending their battery life. Beacon intervals depend on data rate。 they may range from to at 250 kbps. In general, the ZigBee protocols minimize the time the radio is on, so as to reduce power use. In beaconing works, nodes only need to be active while a beacon is being transmitted. In nonbeaconenabled works, power consumption is decidedly asymmetrical: some devices are always active, while others spend most of their time sleeping. V. PROPOSED ALGORITHM A. Basic Algorithm Consider a left side driving system (followed in UK, Australia, India, Malaysia and 72 other countries). This system can be modified for right side driving system (USA, Canada, UAE, Russia etc.) quite easily. Also consider a junction of four roads numbered as node 1, 2, 3 and 4 respectively. Traffic flows from each node to three other nodes with varied densities. Consider road 1 now given green signal in all directions. Fig. 4 Intersection Under Consideration 1) Free left turn for all roads (free right for right side driving system). 2) Check densities at all other nodes and retrieve data from strip sensors.。