Zigbee Wifi Coexistence

Zigbee and Wi-Fi both use the 2.4GHz ISM band and have some overlapping channels.

Zigbee uses very small, narrowband channels compared to Wi-Fi's comparatively large spread-spectrum channels. As a result, Zigbee can "slip inbetween" Wi-Fi networks, like a motorcycle can pass by semi trucks stuck in traffic. Even with a fully deployed Wi-Fi network (using all three non-overlapping channels, 1, 6, and 11) there are still four channels that are totally free. These are Zigbee channels 15, 16, 25, 26, as shown below.

When discussing coexistence, there are two main types of coexistence:
 * Facility-level, ensuring that both Zigbee and Wi-Fi can work in a building
 * Device-level, ensuring that Zigbee and Wi-Fi can both work inside the same device

=Facility Level Coexistence= Zigbee has been used in dense Wi-Fi networks for years, with no ill effects on either the Zigbee network or Wi-Fi network. When deploying Zigbee in areas where there may be many sources of interference:
 * Be flexible - don't just restrict the Zigbee network to one or two channels. Use many channels; e.g. 11,14, 17, etc. This will allow the coordinator in the area to select the channel with the least amount of interference.
 * Be loud - Zigbee radios have varying levels of RF output power, from 0dB to +20dB. Wi-Fi is fairly loud, at +20dB.
 * Be smart - try not to put Zigbee radios right next to a Wi-Fi access point unless you know which channel the access point is on.

One company, Awarepoint has deployed large, multi-million square foot, Zigbee networks in hospitals which are dense with Wi-Fi and other potential interferers.

=Device Level Coexistence= Using both Zigbee and Wi-Fi in the same device is possible. Important to remember:
 * Inside the device keep the two radios as far away as possible
 * Use modules for both, with shields over the radio IC to minimize interference
 * Don't overlap channels - don't use Zigbee channels that overlap with the Wi-Fi channel selected.
 * It is important to have very good decoupling on the power supply lines to avoid coupling.
 * We recommend either a very solid common ground plane, or, having rather wide splits between two separate ground planes, connected only at one point (similar to analog versus digital ground planes).
 * Try to use the lowest RF output power on both that will work in the application.
 * If however one can build some smarts into the software such that the two radios are never operated at the same time -- or at least such that there is never one radio listening and one transmitting at the same time -- then they can be immediately next to each other with no problems.

Additional Information
ZigBee WiFi Coexistence

ZigBee and Wireless Radio Frequency Coexistence