STEALTH COGNITIVE RADIO WITH MIMO ACTIVE INTERFERENCE CANCELLATION ON OFDM SYSTEMS

摘要

In this paper, we present a novel scheme that advances the conventional cognitive radio technology using Detect-And-Avoidance (DAA) approach. In the conventional DAA solution, the utilization of the protected band exclusively belongs to the primary user, which is a waste of bandwidth to the secondary user. We propose a multiple-input multiple- output (MIMO) active interference cancellation (AIC) scheme and show that it creates a deep notch on power spectrum of the protected band to the primary user without the channel state information between the primary user and the secondary user. In the meanwhile, with soft decision MMSE VBLAST (Vertical-Bell Laboratories-Layered-Space-Time) technique, we show the opportunity of the secondary user to utilize the valuable bandwidth of the protected band as well. We have also simulated the proposed scheme with the co-existence of WiMAX (Worldwide Interoperability for Microwave Access) and MB-OFDM UWB (Multi-Band-OFDM Ultra-wideband) devices as the primary user and the secondary user respectively.