Interference cancellation in cognitive radio-based MC-CDMA system using pre-coding technique

In this article, the authors investigate error rate (ER) analysis of multi-carrier code-division multiple access (MC-CDMA) for cognitive radio network (CRN) using the pre-coding technique. CRN is a type of frequency-sensitive device in wireless communication which can intellect the idle spectrum availability and assign the spectrum dynamically for mobile communication. The spectrum is subdivided and its sub-band frequency of CRN is used for implementing multi-carrier (MC) communication and generating the spread of code frequency generation. In this work, pre-processing technique using singular value decomposition is considered for alleviation of the effects of interferences arising from secondary users to ensure a reliable link between the base station and the active users. The null space of channel matrix of active interference primary users has been exploited for the formulation of pre-processing matrix. A time-frequency domain signature sequence has been constructed to suppress the adverse effects of adjacent cell interference (ACI) and secondary multi-user interferences (S-MUI). Further, iterative decoder has been implemented for the achievement of better coding gain when the primary users' signals are contaminated by noise. Simulation ER results of CR MC-CDMA with pre-coding technique for Stanford University Interim and Long-term Evolution channels specification has been presented. It is discerned from ER results that coded CR MC-CDMA system established with pre-processing matrix offers robust performance through vindication of ACI and S-MUI effects while retaining a low complexity of primary mobile station for downlink transmission. Additionally, CRN-based MC-CDMA system has been analysed and found to provide an efficient and flexible solution to fulfil the demands of spectrum utilization.