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

The paper investigates channel pre-equalization for the uplink of multi-carrier code division multiple access (MC-CDMA) mobile cellular systems. This technique solves the crucial problem of uplink 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-to-interference-plus-noise ratio (SINR) at the base station while constraining the power transmitted 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 multiuser detection techniques at the receiver.