Abstract
Cognitive Radio (CR) is considered as a promising approach for efficient utilization of precious radio spectrum resources. In this thesis, we present a new approach that combine active interference cancellation (AIC), Blind Channel Estimation and vertical Bell Laboratories Layered Space-Time (V-BLAST) techniques to transmit data through a multiple-input and multiple-output (MIMO) system within protected band which has been assigned for primary subscribers. This method allows the transmitter to transmit data in the protected band in a stealth fashion (as low as -120dB to -300dB) so that the primary subscribers will be unaware of the transmission. The simulation shows that BER performance in the protected band is as good as in the unprotected band. We have also construct a blueprint by simulating the scheme with the co-existence of 3.5G WiMAX and MB-OFDM UWB devices.