SINR-based channel pre-equalization for uplink multi-carrier CDMA systems

This paper investigates channel pre-equalization for the up-link of multi-carrier code division multiple access (MC-CDMA) mobile cellular systems. This technique solves the crucial problem of up-link channel estimation by keeping the high spectral efficiency of MC-CDMA with no need of pilot symbols. We study an optimisation criterion based on the maximization of the signal over interference plus noise ratio (SINR) at the base station while constraining the transmitted power by the mobile stations. The optimum algorithm is derived and a sub-optimum version is proposed to reduce the computational complexity in the mobile station. Simulation results on Rayleigh fading channels show that SINR-based pre-equalization systems achieve performance that are much better than systems using either conventional pre-equalization techniques at the transmitter or multi-user detection techniques at the receiver.