上浒充通大￥ Cognitive Radio Networks (CRN) SHANGHAI JIAO TONG UNIVERSITY ▣Cognitive Radio A promising solution to spectrum shortage Dynamic Spectrum Access Fixed Channel Access Dynamic Channel Access ISM Bands Licensed Bands ISM Bands Licensed Bands idle Unlicensed Users Licensed Users Unlicensed Users Licensed Users Secondary User(SU)Primary User(PU) 44 Cognitive Radio Networks (CRN) ❑ Cognitive Radio ➢ A promising solution to spectrum shortage ❑ Dynamic Spectrum Access ISM Bands Licensed Bands Unlicensed Users Licensed Users Fixed Channel Access 1 2 3 ISM Bands Licensed Bands Unlicensed Users Licensed Users idle Dynamic Channel Access 1 2 3 Secondary User (SU) Primary User (PU)