Subchannel Power-Loading Schemes in Multiuser OFDM Systems

Achievable bit rates for a number of continuous and discrete bit-loading schemes for multiuser orthogonal frequency-division multiplexing (OFDM) systems are studied. A computationally efficient simple-to-implement discrete bit-loading scheme based on equal-power allocation is proposed and shown to provide close-to-optimal performance. The proposed scheme provides a significant improvement over the traditional discrete equal-power allocation scheme used by medium-access control layer resource-allocation algorithms, particularly when the average user subchannel gains are quite different.