Interference cancellation in multiuser hybrid overlay cognitive radio

In this paper, we consider an overlay cognitive radio (CR) consisting of a primary macro-cell and cognitive small cells of cooperative secondary base stations (SBS).We suggest studying a hybrid CR where a filter bank multicarrier (FBMC) is used for the secondary users (SU) whereas the primary users (PU) are based on orthogonal frequency division multiplexing (OFDM). Compared to OFDM, FBMC has the advantage of reducing the SU interference level that is induced by the differences between the SBS and PU carrier frequency offsets (CFO). Our contribution is threefold: 1/ we derive the interference expression due to SU at the PU receiver, 2/ we propose to use zero forcing beamforming (ZFBF) to cancel the interference, 3/ a comparative study with CR based on OFDM for both the PU and the SU confirms the efficiency of the proposed scheme.