Potentials and limits of secondary spectrum usage by CDMA base stations

With the progress of transmission technology and fast growing demand for ubiquitous high speed wireless services, it is clear that the pressure towards more flexibility in usage of limited spectrum will increase. With concept of spectrum sharing, in this paper, we study potentials and limits of secondary spectrum usage of a television broadcasting band by CDMA base stations. To ensure the performance of primary receivers, we examine transmit power, coverage, and user admissibility of secondary transmit as limits of secondary spectrum usage. By analytical and numerical results, we also describe potentials of secondary spectrum usage concerning with primary exclusive region where the primary users should be protected.