Beacon/non-beacon

There are two modes of operation with the MAC layer:

Non-beacon mode: use CSMA/CA


The device that wants to transmit looks to see if the channel is free. If this is the case, then it passes otherwise it expects a random period.   It’s used for sensors (switch type) that sleep most of the time.

This mode optimize the battery life of the sensors and use the channel only if it is necessary to transmit useful data.

 

Beacon mode: send a beacon at regular intervals to synchronize all devices








Devices (including the coordinator) operate independently but to communicate on the network they need to know when to wake up to transmit. For this it is necessary that they synchronize with the awakening of the coordinator with a beacon.



When a beacon is received, all devices are informed of the duration of the period of activity of the coordinator and when the devices can transmit useful data. They will also receive an indication as to know when the coordinator goes into hibernation and for how long. As devices know when they can hibernate or transmit.



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Source
<p class="MsoNormal" style="text-align:justify">https://fr.wikipedia.org/wiki/IEEE_802.15.4

http://www.tutorial-reports.com/wireless/zigbee/zigbee-traffic-types.php