CAPACITY ENHANCEMENT OF MC-CDMA SYSTEM THROUGH RECEIVER PHASE ROTATED CONJUGATE ICI CANCELLATION WITH ITERATIVE CFO AND IQ IMBALANCE ESTIMATION AND COMPENSATION

The ever increasing demand for very high data rate multimedia services such as audio, video, image and data requires the technologies which make use of the available electromagnetic resources in the most intellectual manner. Multi-carrier code division multiple access (MC-CDMA) is one of the best techniques to meet the requirements of next generation wireless mobile communication systems. MC-CDMA system combines 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. Direct conversion receivers in multi-carrier systems are very sensitive to carrier frequency offset (CFO), gain and phase offsets called IQ imbalances. CFO leads to loss of orthogonality among the subcarriers resulting in intercarrier interference (ICI). IQ imbalance will cause severe degradation in the detection accuracy. To reduce the ICI and to improve the demodulation accuracy, a receiver phase rotated conjugate cancellation (RPRCC) using joint iterative CFO & IQ imbalance estimation and compensation algorithm is proposed in this work. Simulation results show that the proposed method provides better carrier to interference ratio (CIR) and bit error rate (BER) performance compared to phase rotate