Iterative detection and channel estimation for MC-CDMA

Multi-carrier code division multiple access (MC-CDMA) systems are under intense investigation for high bit rate wireless communications systems. Their equalization is based on the fast Fourier transform, allowing for an efficient implementation. Iterative receivers with joint detection and decoding have been shown to achieve very good performance for direct-sequence (DS)-CDMA systems. We apply this concept to MC-CDMA, the multiuser detector is implemented as parallel interference canceller with post-minimum mean squared error filtering. In this contribution a new pilot based channel estimation scheme based on random time sequences is developed. The presented simulation results for a multi path scenario show, that in a fully loaded system with 64 users the single user bound can be approached up to 1 dB. A bit error rate (BER) of 10^-3 is reached already at an E_b/N₀ of 12 dB with a 4 state, rate 1/2 convolutional code.