Spectrum underlay

Spectrum underlay technique is a spectrum management principle by which signals with a very low spectral power density can coexist, as a secondary user, with the primary users of the frequency band(s).

The primary users deploy systems with a much higher power density level. The underlay leads to a modest increase of the noise floor for these primary users.

Ultra Wide Band (UWB) and other spread spectrum technologies can use a spectrum underlay.