Recently

multicarrier(MC) transmission schemes have been introduced into CDMA (Code division multiple access) systems to get such advantages as bandwidth efficiency

resistance to multipath fading and high data-rate transmission etc.In this paper

a new model of MC/CDMA system is proposed for forward links transmission.In the proposed systems

the user estimates all subchannels' fading amplitudes and feeds back all indices of its interested subchannels (whose fading amplitude can be accepted) to the basestation

Based on the indices information

we propose a new subchannel allocated method similar to the water-filling (WF) principle.Theoretical and simulation results show that the average performance in the proposed system can be improved compared with that only using the favorite subchannel for each user

given the condition that the random signature sequences are used.