Blind space-time equalization/decoding with carrier frequency synchronization in multicarrier CDMA systems

Diversity technology is an effective technique to combat channel fading. The multicarrier modulation code division multiple access (MCM-CDMA) technique, or the orthogonal frequency division multiplexing code division multiple access (OFDM-CDMA) scheme, can sufficiently utilize subcarrier diversity; therefore it is broadly considered as an effective approach for future wireless multimedia communications. It is very sensitive to a carrier frequency offset, while the orthogonal property between the subcarriers is lost with carrier drift. A space-time constant modulus algorithm (ST-CMA) is implemented for equalization and decoding of MC-CDMA signals in the frequency domain, with carrier frequency synchronization at the same time. The proposed method has faster convergence rate and less computational complexity, without requiring the periodic transmission of training blocks. Numerical simulations illustrate the effectiveness of this algorithm.