Performance and analysis of hybrid overlay underlay Cognitive Radio waveform in fading Channel

Spectrum Overcrowding continues to present a fundamental challenge for both military and commercial communications as earlier concerns over spectrum congestion and inefficient usage are manifest with 4G system emergence. Interest in Cognitive radio (CR) remains strong as the communication community strives to solve the spectrum congestion problem. In conventional CR Implementation, interference to primary users is minimized using either overlay or underlay waveforms.The overlay waveform that exploit unused spectrum holes and the underlay waveforms that spread their power spectrum density over an ultra-wide bandwidth. The proposed hybrid overlay underlay waveform that exploits both unused and underused waveform which effectively utilize the spectrum and improve spectrum efficiency.