  OFDMA systems are considered as the promising multiple access scheme of next
generation multi-cellular wireless systems. In order to ensure the optimum
usage of radio resources, OFDMA radio resource management algorithms have to
maximize the allocated power and rate of the different subchannels to the users
taking also into account the generated co-channel interference between
neighboring cells, which affects the received Quality of Service. This paper
discusses various schemes for power distribution schemes in multiple co-channel
cells. These schemes include centralized and distributed solutions, which may
involve various degrees of complexity and related overhead and may employ
procedures such as linear programming. Finally, the paper introduces a new
solution that uses a network flow model to solve the maximization of the
multi-cell system sum rate. The application of spatial beamforming at each cell
is suggested in order to better cope with interference.
