{"id":10380,"date":"2026-09-10T07:20:00","date_gmt":"2026-09-10T05:20:00","guid":{"rendered":"https:\/\/www.lukaswojcik.com\/blog\/?p=10380"},"modified":"2026-10-24T04:16:23","modified_gmt":"2026-10-24T02:16:23","slug":"sharing-2-4-ghz-what-a-zigbee-channel-change-costs","status":"publish","type":"post","link":"https:\/\/www.lukaswojcik.com\/blog\/en\/smart-home\/sharing-2-4-ghz-what-a-zigbee-channel-change-costs\/","title":{"rendered":"Sharing 2.4 GHz: What a Zigbee Channel Change Costs"},"content":{"rendered":"

A Zigbee channel change can improve an unreliable mesh, but may also interrupt communication and leave individual devices needing attention. Before changing the network, the useful checks are the occupied Wi-Fi channels, channel width, coordinator placement and actual message reliability. No Zigbee channel is permanently free of interference.<\/p>\n

\"Centre
Centre frequencies are planning aids, not promises of interference-free operation. Migration support and post-change device checks matter as much as channel separation.<\/figcaption><\/figure>\n

Channel numbers describe frequency, not guaranteed separation<\/h2>\n

For the 2.4 GHz Zigbee channels 11\u201326, the centre frequency is 2405 MHz plus 5 MHz for each step above channel 11. The signal occupies roughly 2 MHz. Modern 2.4 GHz Wi-Fi commonly uses 20 MHz channels; the familiar 22 MHz drawing describes legacy DSSS operation. Neither drawing is a hard wall beyond which a strong transmitter has no effect.<\/p>\n

Zigbee centre (MHz) = 2405 + 5 \u00d7 (channel \u2212 11)\nZigbee 11: 2405    15: 2425    20: 2450    25: 2475    26: 2480\nWi-Fi   1: 2412     6: 2437    11: 2462    13: 2472\nNumbers are centre frequencies, not interference-free boundaries.<\/code><\/pre>\n
Wi-Fi 1, 6 and 11 form a common three-channel plan. Other channels exist where permitted and supported; the plan is not a statement that only these three numbers can work. Zigbee 15, 20 and 25 are useful candidates around that particular Wi-Fi arrangement, not universally clear channels. Wi-Fi 13 changes the situation near Zigbee 25 and 26. Actual nearby access points, widths and signal strengths determine the choice.<\/p>\n
Interference depends on received energy and airtime<\/h2>\n
Neither Wi-Fi nor Zigbee has one universal transmit power. The important conditions include received signal strength, distance, antenna placement, receiver filtering and how much time each radio transmits. A nearby busy access point can overwhelm a weak Zigbee link even when a simplified channel diagram suggests a gap.<\/p>\n
Both systems use mechanisms to avoid collisions. Wi-Fi does not decode a Zigbee packet as a Wi-Fi packet, but sufficiently strong non-Wi-Fi energy can still affect channel assessment. The claim that Wi-Fi never hears Zigbee is therefore too absolute. Carrier sensing also cannot eliminate every collision, particularly when transmitters cannot hear each other. Delayed or lost messages are possible in both directions.<\/p>\n
Reduce local interference before moving the mesh<\/h2>\n