It is well known that Xiaomi's smart set includes 4 cases, human body sensors, doors and windows sensors, wireless switches and multi-function gateways, based on NXP-based ZigBee RF chips - JN5168 for networking communication. The multi-function gateway is access to Xiaomi Cloud and other smart devices via Wi-Fi technology.
In the above figure, we can see that the Multi-function gateway of Xiaomi integrate the ZigBee chip JN5168 and Wi-Fi modules to a small board. This Zigbee program and Guangzhou Zhiyuan Electronics launched ZM5168 Zigbee module is the same program, we know the ZM5168 product introduction, the ZigBee channel used by this chip is 2.4GHz. ZigBee Protocol 802.15.4 Standards 2.4 GHz ISM bands into 16 channels, each channel bandwidth is 2 MHz, and the ZigBee spectrum list is as follows
Wi-Fi's standard operating frequency band of 802.11b / g is 2.4GHz (2.4GHz-2.4888GHz), divided into 14 channels, each channel bandwidth is 22MHz, Wi-Fi spectrum list as follows:
We can see from ZigBee and Wi-Fi we can see that the frequency they work is conflicting with each other. In the predecessors, we know that the presence of Wi-Fi interference results in a ZigBee network packet loss rate, from the transmission power, the CSMA mechanism rollback time, data frame interval, all of which can be seen from Wi-Fi. The node has an overwhelming advantage in obtaining the channel, thus generating a serious impact on the communication performance of the ZigBee network.
So, how is the smart gateway to work with WiFi and ZigBee together like a Xiaomi Smart Home Set Gateway, how is ZigBee to coexist with Wi-Fi? This is an urgent problem to be solved and directly affects whether the ZigBee network can be intelligently homing. In response to this problem, Xiaobian made a few personal opinions for your reference.
Solution 1: The ZigBee network and Wi-Fi in the intelligent gateway use a disciplined communication mechanism to avoid conflicts. When communicating, the intelligent gateway is kept away from the Wi-Fi router, and the attenuation of the electromagnetic wave is transmitted in air to reduce the interference of the ZigBee signal to the ZigBee signal.
Solution 2: Method One is physically resolved interference from the Wi-Fi signal on the ZigBee network, but in practical applications, the distance between the intelligent gateway and the router is uncontrollable, or by the user's usage habits and home layout decisions So we only achieve interference from the ZigBee network with the anti-interference algorithm through ZigBee.
Here is a small article that is called Muzi-Mulit Channel Zigbee (multi-channel Zigbee) communication mechanism algorithm, and automatically avoids the interference of the Wi-Fi signal on the ZigBee network.
First, through ZigBee's CCA (Channel Idle Assessment) mechanism, the interference detection is initiated, the interference level within the surrounding range is evaluated. If the Wi-Fi interference around it is considered to have a certain degree, it will increase the link performance. Start the channel switching process. The ZigBee module of ZM5168 built-in FastzigBee protocol has a unique interference detection algorithm.
Second, the channel switching, when the signal is switched, in order to avoid excessive signal switching, we need the number of signals of the entire network as possible. Therefore, a neighbor channel table is maintained at each node, each table entry is
, where NGH is the current working channel of the NGH, CH is the current work channel of NGH. Whenever the channel switching, it informs the target channels its selected target channel.
It is necessary to maintain connectivity of the entire network, and rebuild the approach node channel table after ensuring that the adjacent node is switched.
More about ZigBee and Wi-Fi, you can consult Guangzhou Zhiyuan Electronics Zigbee Product ZM5168 Series.
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Source: Wiku Electronic Market Network
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