Increasing spectrum utilization in wireless infrastructure-based systems

Resent measurements and reports show that in most cases licensed spectrum is used sporadically resulting in large unutilized spectrum portions. Opportunistic spectrum access (OSA) is a promising solution providing methods to identify and exploit these portions. Most existing OSA proposals provide ways for unlicensed users to access the licensed spectrum. This paper describes a novel approach where licensed users of an infrastructure-based system exploit features of their system to detect spatial spectrum opportunities. Focusing on an interference-free solution, an alternative opportunistic operation mode is provided, allowing licensed users to increase utilization of their own spectrum.