Interferencia do zigbee

MICAz-Based ZigBee and WiFi Coexistence

Avoiding RF Interference Between WiFi and Zigbee
This application note discusses how to avoid RF interference when deploying WiFi and IEEE
802.15.4 / Zigbee radios simultaneously or in close proximity. The testing and deployments conducted for this application note used Crossbow’s MICAz Zigbee-ready wireless Smart-Dust sensors and a Crossbow Stargate Gateway running both high-power and low-power WiFi cards.
When properly configured, the issue of RF interference and lost data can be avoided. However, without proper care and software configuration serious interference issues can occur.
Disclaimer: Crossbow does not represent this as a complete study, but it is merely practical tips for deployment based on our experience in the field. We also can’t confirm whether these test would be relevant for other manufacturers hardware.
WiFi and IEEE802.15.4 / ZigBee Sprectrum
To understand the potential for problems, a review of the RF spectrums and available channels for WiFi (802.11b/g) and Zigbee (802.15.4) is shown below. Since the RF channels in ZigBee and WiFi overlap there is a cause for concern. This concern has also been shown to be an issue in field testing, as discussed later in this application note.

Table 1: WiFi RF Channels

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MICAz-Based ZigBee and WiFi Coexistence
Figure 1 shows the RF channel spectrum of IEEE801.15.4 / ZigBee against IEEE802.11b / WiFi.

Figure 1: IEEE802.15.4 and IEEE802.11 Channels
What is an RF Spectrum ?
To users who are new to RF and Wireless technologies, an RF spectrum plot as shown in Figure 1 is a graphical way of showing how much energy and at what frequencies a radio operates. The Y-axis is the RF energy or power, and the X-axis is the frequency. Think of the frequency as the “radio station”, that the device transmits on. Because both ZigBee and WiFi are “spread spectrum”, they do not operate on a single radio channel, they actually occupy bands of