A cognitive radio(CR) is a radio that can change its transmitter parameters based on interaction with the environment where it operates.It can be used to improve the spectrum access and efficiency of spectrum use;especially it enables unlicensed users to use licensed spectrums.It also makes networks and terminals more flexible.This paper describes the definition and concept models of cognitive radio,analyzes its characteristics and performance assessing parameters,and discusses such key issues as interference temperature,spectrum pooling sharing,and dynamic spectrum management,introduces the current progress of the study.Finally,it provides a few research ideas according to application requirements.