| 单词 | ZigBee |
| 释义 | ZigBee resiliency. ZigBee runs in the ISM band using direct sequence spread spectrum (DSSS) transmission. A ZigBee Coordinator (ZC) initializes the network, coordinates its operation, and is responsible for security. ZigBee End Devices (ZEDs) are terminal devices that are very limited in function, and can communicate only with ZigBee Routers (ZRs), which function to pass messages to other ZRs or to the ZC. In beacon enabled networks, ZigBee Routers (ZRs) periodically beacon their presence and, therefore, need power up only during the beaconing cycle, which conserves battery life. In non–beacon enabled networks, all devices remain active all the time and employ the carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) mechanism. Although most devices run in the 2.4 GHz range, some run at 915 MHz (Americas) and 868 MHz (Europe) ranges, as those bands offer better signal propagation through physical obstructions such as walls, floors, ceilings, and windows. Depending on the frequency band selected, raw data rates are 20 kbps (1 channel at 868 MHz), 40 kbps (10 channels at 915 MHz), and 250 kbps (16 channels at 2.4 GHz). Specified modulation techniques are binary phase-shift keying (BPSK) in the 868 and 915 MHz bands, and quaternary phase-shift keying (QPSK) in the 2.4 GHz band. Distances range from 10 meters to 100+ meters, depending on frequency, power output, and environmental characteristics. Devices generally transmit at a maximum power level of approximately 1 mW. Security features include access control and encryption based on the advanced encryption standard (AES). ZigBee is theoretically scalable up to 65,536 devices.The term ZigBee refers to the technique, known as the ZigBee principle, that a domestic honeybee uses to communicate the location of a new food source to other members of the colony. See also ad hoc, AES, BPSK, CSMA/CA, DSSS, frequency band, ISM, MAC, mesh topology, peer-to-peer, propagation, QPSK, star topology, WPAN, ZC, ZED, ZigBee principle, and ZR. |
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