Joint UKF and MMSE Channel Estimation for Uplink 2-Dimensional Block Spread MC-CDMA with Cyclic Delay Transmit Diversity

Multi-access interference (MAI) free uplink transmission can be achieved by 2-dimensional (2D) block spread code division multi access (CDMA), and low-complexity single-user frequency-domain equalization (FDE) is performed at base station to obtain the frequency diversity gain. Cyclic delay transmit diversity (CDTD) can further improve the transmission performance by obtaining a larger frequency diversity gain in the frequency selective fading channel. However, accurate estimation of the channel transfer function is the premise for the use of 2D block spread CDMA with CDTD. Unscented Kalman filter (UKF) is an attractive technology and suitable for the Rayleigh channel estimation in time domain, which can be used to assist the minimum mean square error (MMSE) criterion based channel estimation (CE) to improve the BER performance. This paper proposes a joint UKF and MMSE criterion CE method. The achievable uplink BER performance is evaluated by computer simulation for 2D block spread multi-carrier (MC) CDMA, which shows that the joint CE can improve the BER performance about 0.8dB compared with MMSE-CE when BER=10^-4.