Multi-carrier DS-CDMA with adaptive sub-carrier hopping for fading channels

A modified multi-carrier (MC) DS-CDMA system has been proposed for use over slow multi-path fading channels with frequency selectivity in the reverse link transmission of the cellular network. Instead of transmitting data sub-streams uniformly through sub-channels, data sub-streams hop over sub-channels with the hopping patterns adaptively adjusted to the channel fading characteristics. The problem of determining the optimal hopping pattern is formulated as a multi-objective optimization problem, for which an efficient algorithm is designed to solve the problem practically. Simulation results show that the performance in terms of the average system bit error probability (BER) is better than that of a single carrier RAKE system, conventional MC CDMA systems applying moderate error protection and diversity systems with different combining techniques.