BER Performance Maintenance in TURBO Coded OFDM in Cognitive Radio

Spectrum measurements show that wide ranges of the spectrum are rarely used most of the time while other bands are heavily used. However, those unused portions of the spectrum are licensed and thus cannot be utilized by users other than the license owners. Hence, there is a need for a novel technology that can benefit from these opportunities. Cognitive radio is a promising concept that offers solution to spectral crowding problem by introducing the opportunistic usage of frequency bands that are not heavily occupied by licensed users. As the spectrum is underutilized by the primary license holders, there exists spectrum holes that can be used by secondary users, yielding efficient utilization of the spectrum and eliminating the apparent spectrum scarcity