Multi-Antenna Interference Cancellation for Black Space Cognitive Radio Communications

This paper focuses on multi-antenna interference rejection based black-space cognitive radio (BS- CR) schemes. The idea of BS-CR is to transmit secondary user (SU) signal in the same frequency band with the primary user (PU) such that SU´s power spectral density is clearly below that of the PU, and no significant interference is inflicted on the PU receivers. Advanced interference cancellation techniques allow such operation mode, which enables effective reuse of the PU spectrum for short-distance communication. This study aims at investigating the performance of multi antenna based co-channel interference suppression at the secondary receiver. The interference suppression capability of minimum mean square error (MMSE) based multi-antenna Interference Rejection Combining (IRC) is analyzed under the BC-CR framework. The performance of the IRC scheme is examined under different modulation and diversity orders and interference levels. In our case study, the proposed secondary communication system uses OFDM based 802.11af technology operating in the terrestrial TV frequency band, within an active DVB-T transmission channel.