how does zigbee system works


ZigBee is a wireless connection, can work in three frequency band of 2.4GHz (global epidemic), 868mhz (Europe) and 915 MHz (American pop), respectively, with the transmission rate of the highest 250kbit/s, 20kbit/s and 40kbit/s. Its transmission distance in the range of 10-75m, but can continue to increase. As a wireless communication technology, ZigBee has the following characteristics:
(1) low power consumption: due to the low transmission rate of ZigBee, the transmit power is only 1mW, and the sleep mode is adopted, the power consumption is low, so the ZigBee equipment is very efficient. According to estimates, ZigBee devices only two No. 5 batteries can be maintained for up to 6 months to 2 years of time, which is unmatched by other wireless devices.
(2) low cost: the initial cost of the ZigBee module is around $6, and it is estimated to be 2.5 to 1.5 U.S. dollars very quickly, and the ZigBee agreement is royalty free. Low cost for ZigBee is also a key factor.
(3) the delay is short: the delay of the communication delay and the time delay are very short, the typical search equipment delay 30ms, the time delay of sleep activation is 15ms, the time delay of the active device channel is 15ms. Therefore, ZigBee technology is applicable to wireless control (such as industrial control applications, etc.) with time delay.
(4) network capacity: a star structure of the Zigbee network can accommodate up to 254
A maximum of 100 ZigBee networks can exist simultaneously in a region, and the network is composed of a device and a main device.
(5) reliability: a collision avoidance strategy is adopted, and a dedicated time slot is reserved for communication services that need to be fixed bandwidth to avoid the competition and conflict of the sending data. The MAC layer uses a fully recognized data transmission mode, each of the packets sent must wait for the recipient's confirmation message. If there are problems in transmission can be retransmitted.
(6) security: ZigBee provides a data packet integrity check function based on the cyclic redundancy check (CRC), which supports authentication and authentication, and uses the AES-128 encryption algorithm, each application can flexibly determine its security attributes.