In this paper, a practical eigenmode based scheduling algorithm with double loops (ESDL) is proposed for multi-user MIMO/OFDM systems. The wireless channels are decomposed into several eigenmodes, and the eigenmode based power allocation is formulated into an optimization problem, whose object is to maximize the system capacity while guaranteeing users' QoS requirements. By replacing the QoS constraints with penalty functions, the problem is reformulated to a penalty problem with a given penalty factor, which is solved by a greedy power allocation (GPA) scheme as the inner loop. The penalty factor is then updated in the outer loop according to QoS constraints. Numerical results show that compared with other algorithms proposed in the literature, ESDL can result in significant improvement in channel efficiency, while at the same time guaranteeing minimum data rates of users.
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