A low complexity receiver phase rotated conjugate cancellation for ICI reduction using iterative ML algorithm in MC-CDMA system

The convergence of high data rate multimedia services such as speech, audio, video, image and data will be the main features of future wireless systems. Multi-carrier code division multiple access (MC-CDMA) is one of the powerful techniques to meet the requirements of next generation broadband and wireless mobile communication systems. MC-CDMA system allows many users to get the benefit of both orthogonal frequency division multiplexing (OFDM) technique and code division multiple access scheme (CDMA). It offers high spectral efficiency, high data rate, low transmit power, lower implementation complexity, large system capacity and narrowband interference rejection capability. Multicarrier systems are very sensitive to carrier frequency offset (CFO) caused by Doppler shifts and imperfections of transmitter and receiver oscillators, which leads to loss of orthogonality among the subcarriers resulting in intercarrier interference (ICI). In this paper, a low complexity receiver phase rotated conjugate cancellation (RPRCC) algorithm using an iterative maximum likelihood (ML) based CFO estimation is proposed. The proposed method reduces the ICI which in turn reduces the multiple access interference (MAI) and subsequently increases the system capacity. Simulation results show that the RPRCC method provides better carrier to interference ratio (CIR) and bit error rate (BER) performance compared to transmitter phase rotated conjugate cancellation (PRCC) technique and conventional conjugate cancellation (CC) scheme.