Subchannel power allocation and rate adaptation for a MC-CDMA system satisfying mixed QoS requirements

In this paper a power and rate adaptation algorithm for a MC-CDMA system with different quality of service (QoS) requirements is proposed. We consider the forward transmission case where different classes of data are simultaneously transmitted for different active users. The system allocates different data streams over different subchannels or blocks according to the each user's CSI, and assigns to each stream a priority grade according to the QoS experienced and needed by each user. The classical water-filling algorithm is here adapted to cope with the spreading codes and the bit allocation. Results show that the total data rate gets closer to the channel capacity while the QoS requirements are met.