Novel approach for blind spectrum sensing in time and frequency domain

Cognitive radio is a new concept of reusing licensed spectrum in an unlicensed manner. The spectrum must be sensed to detect primary user signals, in order to allow cognitive radios in a primary system. Spectrum sensing is to be done over a wide range of the electro-magnetic spectrum. While many of the signals of interest are similar in terms of the modulation techniques used, the characteristics of the transmission channel experienced by these signals can vary considerably depending upon the frequency range of operation. In the recent scenario 802.16 (commercially known as WIMAX) uses scalable OFDMA as physical layer transmission technique. This paper explores the issues in coexistence between cognitive systems and WiMax. Performance evaluation is done for time domain and frequency domain spectrum sensing techniques using time varying channel conditions.