Opportunities for a more Efficient Use of the Spectrum based in Cognitive Radio

Different studies about the use of radio spectrum have shown the existence of underutilized bands, like the ones destined to television broadcasting. This provides an interesting opportunity considering the exponential growth in wireless communications and applications, which results in an important demand for higher bandwidth to achieve an adequate performance. To operate in bands that are already licensed, it is necessary to ensure that this operation does not cause any interference to the primary user, and always gives priority to it. In this context the IEEE has been defining a standard with functionalities of Cognitive Radio that allows operation in licensed bands opportunistically, and without causing interference. From there comes the IEEE 802.22 standard, which has a set of features and procedures to measure, monitor and manage the radio spectrum, essential to ensure the protection of primary user's transmissions. Some pilot projects have demonstrated the potential of this standard to provide broadband services comparable to classical ADSL services, especially in remote or rural areas inaccessible to deploy fixed networks. One of the great challenges to install such systems commercially, is to achieve the permissions for the operation and to have a defined regulation for these systems, decisions that are in the hands of the telecommunications services regulators in each country. This paper presents an overview of these issues with the intention of promoting a more efficient use of the spectrum.