A pre-whitening scheme in a MIMO-based spectrum-sharing environment

In this letter, we propose a pre-whitening scheme for a spectrum-sharing environment where multiple antennas are used for both primary and secondary users. The proposed pre-whitening scheme is different from the conventional postwhitening scheme for mitigating multiple-input and multipleoutput (MIMO) interference because a primary receiver does not require any pre-knowledge about the interference channel which is a more proper assumption in a spectrum-sharing environment. Moreover, the proposed scheme outperforms the conventional post-whitening scheme in terms of the secondary user capacity due to its interference-reduction capability.