Modelling and Simulation of Interference Cancellation Receiver for MIMO Multicarrier CDMA based Cognitive Radio

Abstract

In this paper, modeling and simulation of a receiver with interference cancellation technique for the downlink transmission of multiple input multiple output (MIMO) multicarrier code-division multiple access (MC-CDMA) based cognitive radio is investigated. Synchronous transmission of multiple users’ signals over frequency selective Rayleigh channel is considered. Linear MMSE frequency domain equalization is utilized to overcome channel effect. Orthogonal Variable Spreading Factor (OVSF) codes are used to support users of different data bit rates. An adaptive subcarrier deactivation method is proposed for deactivating a set of subcarriers used for downlink transmission by the cognitive radio base station that overlap with primary user’s transmission in order to avoid causing interference to the primary user. Orthogonality between the spreading codes is lost due to subcarrier deactivation which causes interference among secondary cognitive radio users. In this paper a modified Group-wise Successive Interference Cancellation (m-GSIC) technique is proposed to suppress the interference caused due to subcarrier deactivation. The simulation results show that the proposed interference cancellation technique results in better BER performance over conventional interference cancellation techniques