MIMO active interference cancellation for stealth cognitive radio in MB-OFDM UWB

Cognitive Radio (CR) is considered as a promising approach for efficient utilization of precious radio spectrum resources. In this paper, we present a new approach that combine active interference cancellation (AIC) 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 -120 dB to -300 dB) so that the primary subscribers will be unaware of the transmission. We show the opportunity of the secondary user to utilize the valuable spectrum of the protected band as well. The simulation shows that BER performance in the protected band is as good as in the unprotected band. We have also simulated the proposed scheme with the co-existence of WiMAX and MB-OFDM UWB devices as the primary user and the secondary user respectively.