Abstract：Spectrum Sensing is one of the key

technologies in cognitive radio．This article summarize$

the latest development in the field．ana—

lyzes the performance of detection algorithm for

physical layer and its detection policies，examining

the solution for improving the efficiency of

MAC layer detection using the tragic feature of

allthorized USel葛，and discusses about the data

fusion and decision in multi—user collaboration

detection．Based on the above aspects，this article

proposes the topics for further research．