ZigBee and WiFi

It has been a while since I have posted here – must be the summer doldrums. It is time to get more regular in the updates and generate more comments around these postings. All of our customers are now moved onto this portal instead of using e-mail so the portal is getting plenty of traffic.

At the start of the Summer I had some questions within ZigBee and from customers on the selection of channels within ZigBee. In digging in to answer this it seemed like more actual field data was needed. Doing WiFi scans in a given location does a nice job showing access points within range and their signal strength. However, I let the scanning programming running on my morning train ride into Boston. It showed 1500 access points in my 45 minute train ride! This ends up being a great way to gather statistical data on what channels are in use. So during my Summer travels I did these scans at various locations (in the US and Europe so far).

These scans showed typical US WiFi access points are on the recommended channels of 1, 6 and 11 about 85% of the time. In Europe this dropped to closer to 75%. The remainder of the access points are spread relatively evenly as 1-2% across all the other channels. These results indicate the suggested ZigBee channels in the Home Automation and Smart Energy specifications should be the right ones to attempt to stay away from the largest use WiFi channels. If interested, the results are posted on the ZigBee website here — http://www.zigbee.org/imwp/download.asp?ContentID=13781. If you are not a ZigBee member, send me a note and I will send you the results.