Wireless sensor network

　　The wireless sensor network has sensor, the data processing unit and the connection module small pitch point by the random distribution integration through from organization's way constitution, with the aid of the various formats sensor survey which in sets in the pitch point in the peripheral environment is hot, infrared, the sound navigation and ranging, the radar and the earthquake wave signal, thus surveys including the temperature, the humidity, the noise, the light intensity, the pressure, the soil ingredient, the motion object size, the speed and the direction and so on is multitudinous we to be interested the material phenomenon. In mailing address, although may use wired, wireless, infrared and the light and so on the many kinds of forms, but thought generally the short distance the wireless low power communication most suits the sensor network use like active electron label (ACTIVE RFID) the technology, for is clear about in order to, is called as the wireless sensor network generally. But not absolutely, Berkeley Smart Dust because may like the dust equally aerosol in airborne, effectively has avoided obstacle covering, therefore uses the light to take the correspondence medium.

　　The wireless sensor network and the traditional wireless network (for example WLAN and honeycomb mobile phone network) has the different design goal, latter is moving highly in the environment through optimizes the route and the resource management strategy maximization band width use factor, at the same time provides the certain grade of service guarantee for the user. In the wireless sensor network, needs to move besides the minority pitch point, the majority of pitch points all are static. Because they usually move is unable in the close bad even dangerous long-distance environment in the human, the energy is unable to substitute, designs the effective strategy to lengthen network the life cycle to become the wireless sensor network the core question.

　　The active electronic label (RFID) the technology gives without doubt constructs the omnipresent wireless sensor network to bring a time of revolutionary opportunity. The wireless sensor network equipment, or is called "the dust particle sensor (Mote)", may constitutes by the active electronic label and feel unit: Has the networking function and the application software electric circuit board; May examine the temperature, the pressure, the humidity, the light, the sound or the magnetic variation sensor contact surface; As well as may report the survey situation the radio transmitter-receiver set. All these equipment, only need a pair of AA battery power supply. The low cost miniature chip, the low power radio transmitter-receiver set, the wireless networking technology, all these caused the dust particle sensor to complete a huge leap in addition, has gone far beyond for many years to use in surveying each kind of thing (from construction Vibrates the thing temperature to the industrial plant equipment) the traditional sensor. The before sensor needed to connect to the electronic installation on, each sensor cost approximately 200 ~ 400 US dollars, and the service expense very was also high. But each dust particle sensor, the value only then 100 US dollars, install the cost also to have approximately to lower a lot. Along with the low cost active electronic label technology mature development, this price has the possibility in several years to fall to ten US dollars below.

　　Uses the active electronic label a wireless sensor network big breakthrough to lie in one kind specially "the netted network (Mesh Networking)" the software. Majority of all is in this network sensor "Sleep" Condition. If which kind of equipment has had the valuable information, then this kind of component can be short "awakens", then this information transmission to very close remote recent equipment. Here has used one kind the chain type (Bucket Brigade)" the electronic structure, transmits mutually through the active electronic label between moves the data gradually, until transmits to may carry on the memory analysis to these data the central computer, but is not uses each sensor to transmit its information separately to the read-write base depot way. If some sensors are unable to transmit the data, in inlays the type logic to be able to use its neighbor sensor the information to replace the breakdown sensor by to carry on the accurate data transmission. "Awakens" the transmission function to be extremely important. Because all equipment all can preserve the energy, this kind of network defends in nobody value in the situation, may the situation use very long time which needs to transmit unceasingly in the operational site or the data