In this paper we propose a new loading algorithm that maximizes the total data rate of multiuser orthogonal frequency division multiplexing (OFDM) systems in a downlink transmission. The data rate maximization problem is formulated by allowing that a subcarrier could be shared by multiple users. The transmit power adaptation scheme (loading algorithm) is derived by solving the maximization problem via two steps: subcarrier assignment for users and power allocation for subcarriers. In order to reduce the computational complexity level in the proposed transmit power adaptation problem we propose a simple method, in form of theorem, which assignes subchannels to users and distributes power among subchannels. Also, we consider a case which includes constraints on transmit power and bits.

Elektrotehnika