Unlicensed Frequency

In the United States, the FCC defines regulations for unlicensed bands as 902 to 928 MHz and 2400 to 2483.5 MHz.

Licensed Vs. Unlicensed

Licensed	Unlicensed
License required to be purchased	License is free
Medium can be accessed\used only by the owner of the license	Unlicensed spectrum and its medium can be accessed\used by anyone
Permission is required for transmission or reception and scheduling	Anyone can access the medium if channel is empty
Interference management is carried out by careful frequency planning	Interference management can be done using various techniques such as distributed management
Advantages- The benefits of licensed spectrum is known and predictive interference	Advantages- Free or low cost to use, available nearly everywhere, scalable
Disadvantages- high costs for network operators, requires central management, low scalability	Disadvantages- Unpredictable interference (due to lack of QoS), Higher load, Lack of protection from interference due to other systems

For FCC Basics of Unlicensed FCC Basics of Unlicensed
Transmitters click here.

For the National Association of Broadcasters Engineering Handbook, click here.