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Abslmcf-We present adaptive power and bit loading schemes for a bitinterleaved coded OFDM system with perfect cbannel state information and square quadrature amplitude modulation constellations. In order to minimize ths bit error rates at the output of the Viterbi decoder subject to bit rate and power constraints, an analytical expression for the bit error rate of a hard-decision device has to be minimized with respect to the number of bits and the power assigned to the subcarrier channels. The prohibitive complexity of the optimum solution can be circumvented by a simple soboptininm two-step procedure where the bit and power loading parts are dewupled. It is shown by Monte Carlo simulations that for broadband systems with Rayleigh fading the loading procedures provide a SNR gain of up to 6 dB for an average bit eirror rate Level of IO-'.

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