Blind adaptive arrays with subcarrier transmission power assignment for spectrum superposing

This paper proposes an extension scheme of blind adaptive arrays for spectrum superposing in cognitive radio networks. Though Maximal Ratio Combining (MRC) and Power Inversion (PI) are known as one of the blind adaptive array algorithms, MRC strongly receives a desired signal when SIR (at the antenna input)>0dB while PI appropriately suppresses interference signal when SIR<0dB. With the proposed method, the secondary transmitter intentionally provides a level difference between subcarriers. At the receiver side, MRC is applied to the received signals of subcarrier assigned higher power and PI is applied to ones assigned lower power. Computer simulation results show that the proposed scheme can suppress interference around SIR=0dB while improving operational SIR for the primary system over 5dB. Our initial study revealed the validity of the proposed scheme for spectrum superposing.