When you think of Sensor Networks, 2.4GHz transceivers likely come to mind. The CC2420 is one of the most popular transceivers for sensor networks and other applications and it uses 2.4GHz as per Zigbee. Of course, Zigbee does allow Sub-1GHz frequencies, but I’ve yet to see many of those made. Undoubtedly this is due (among other reasons) to the smaller antenna which results in a smaller PCB. However, there are several issues with these transceivers, among them:

• Operating sensor networks and other devices at 2.4GHz can be a coexistance nightmare. Consider that most deployments will be done in urban environments where the 2.4GHz band is saturated with Microwave Ovens, Baby Monitors, Bluetooth, WiFi, etc. A node needing to survive in this environment will experience frequent collisions. There have been several papers analyzing the performance of devices in these conditions and needless to say the results were far from acceptable.
• Decreased range is to be expected from higher frequencies as per the Friis transmission equation.

2.4GHz devices do have some advantages such as popularity, small size, and ease of interoperability. However, next time you consider a transceiver, don’t disregard the sub-1GHz options which might be better.

Some useful transceivers:
TI CC1101 – sub-1GHz transceiver with multiple bands, 10dBm output power, flexible modulation formats and 500kbps
TI CC2520 – 2.4GHz Zigbee compliant transceiver

There are many other manufacturers of RF Transceivers (especially Zigbee/ 802.15.4) such as Microchip, but I listed TI transceivers because they seem to be quite predominant in the market and I’ve personally used them in several projects. The CC2520 is an update to the CC2420.