On power allocation in adaptive cyclic prefix OFDM

We consider the problem of the joint allocation of power and cyclic prefix (CP) duration to maximize the system capacity in orthogonal frequency division multiplexing (OFDM). A closed form solution to the problem does not exist and the exhaustive search of the optimal values is practically unfeasible. Therefore, we propose a sub-optimal iterative power allocation algorithm jointly with the CP adaptation to see whether capacity improvements can be obtained w.r.t. the conventional choice of a uniform power distribution over the sub-channels and a predetermined long CP value. Numerical results show that via power and CP adaptation significant improvements can be obtained.