ABSTRACT
In order to overcome the fixed and inflexible spectrum allocation new approaches in the spectrum regulation and in the development of enhanced wireless devices become mandatory. At present, regulation authorities assign fixed frequency bands to different subscribers or service providers who have to operate in the licensed band only. This procedure was already formulated in 1920 and may not be able to meet tomorrow’s needs [1]. Due to the fixed allocation of the frequency bands to specific users or operators the utilization of the spectrum is not always very efficient. Recent studies have shown that only about 10% of the allocated spectrum in the United States and Europe are utilized [2-4]. In contrast to a fixed assignment of services and frequency bands the demand on several services varies over time and place that results in a highly temporal and geographical variation of the spectral utilization. Therefore, the interest regarding new ways of using, allowing access to, or allocating spectrum by increasing the spectrum efficiency has been grown in many regulatory bodies and standardization groups.
