Title: Modified hybrid interference cancellation algorithm for uplink cognitive radio transmission based on overloaded DS-CDMA
Authors: S. Mohandass; G. Umamaheswari
Addresses: Department of Electronics and Communication Engineering, PSG College of Technology, Peelamedu, Coimbatore – 641004, India ' Department of Electronics and Communication Engineering, PSG College of Technology, Peelamedu, Coimbatore – 641004, India
Abstract: In this paper, cognitive radio network architecture based on overloaded direct sequence code division multiple access (O-DS-CDMA) is proposed. In this method, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. Orthogonality between the spreading codes is lost due to non-zero cross correlation between the codes and timing synchronisation error in the uplink transmission, which causes interference among primary and secondary users. In this paper, a modified hybrid parallel/successive interference cancellation algorithm is proposed for the primary and secondary user base station receivers with multiple antennas, to suppress the interference among the users. Interferences among same group users are cancelled using parallel interference cancellation and the interferences between groups are cancelled using successive interference cancellation. The simulation results show that, the proposed modified interference cancellation algorithm improves the BER performance of the system significantly.
Keywords: cognitive radio; overloaded DS-CDMA; orthogonal gold codes; hybrid interference cancellation; HIC.
International Journal of Information and Communication Technology, 2017 Vol.10 No.4, pp.454 - 467
Received: 30 Jun 2014
Accepted: 13 Oct 2014
Published online: 27 Apr 2017 *