White space

In wireless telecommunications, white space refers to geographic regions where wireless frequencies assigned to a particular licensed user are not in use and may be opportunistically used by a third party.

TV white spaces refers to a geographic spectrum sharing strategy of the television broadcast bands authorized by a national telecommunications regulator. The specific band, channel plan and detailed spectrum sharing rules may differ by jurisdiction, but generally follow the following strategy:

• A geographic contour is calculated around a licensed service provider to establish the geographic extent of that station's service area and exclusive right to use a frequency channel. Examples of licensed service providers include broadcast television stations, professional audio and news gathering organizations, and public safety agencies like your local police and fire departments.

• A separation distance is calculated and buffers a licensed geographic contour to ensure no service degradation or signal interference will occur within the licensed service area. Separation distance is calculated using the desired or maximum transmit power of the secondary (i.e. unlicensed) user.

• For positions within the geographic contour the licensed user retains exclusive rights to use their assigned frequency channel. For all positions outside the geographic contour (plus separation distance) the frequency channel may be exploited by other services and users.

In summary: TV white space is wireless spectrum available for use, typically by non-licensed operators, anywhere outside of a licensed user's exclusive geographic service area (plus separation distance).

Spectrum access system

The primary method of preventing interference to licensed users is a geo-location database, also called a spectrum access system (SAS).

In TV white space, the SAS provides two basic functions. These are

1. Serve as a registrar for licensed users to register and establish geographic protections.
2. Serve as a frequency coordinator for secondary users to discover and access available channels.

Registrar

This SAS provides several convenient registration forms for licensed users to register and establish geographic protections.

Additionally, this SAS provides a convenient registration form unlicensed users to receive authentication and authorization credentials to access the SAS frequency coordination capabiliites.

Frequency coordination

Wireless operating rules generally require a secondary (unlicensed) white space device to contact an authorized SAS to obtain a list of channels available for their operation at their individual locations. Such devices may only operate on those available channels and are required to provide their immediate geographic location. The database then returns a list of the channels available for operation by the device for its reported location.

This SAS provides automated, machine readable resources for TV white space radio access devices to discover and and access available channels at their desired operating position.