Abstract:

An efficient power and bit allocation algorithm based on IWFP（Iterative WaterFilling Power） algorithm is proposed for the adaptive OFDM (Orthogonal Frequency Division Multiplexing) systems. The traditional iterative water-filling power allocation algorithm needs high scale of constellation quantitative and does not fit for the practical applications. The proposed algorithm has a bit and power allocation of secondary adjustment, which conforms to the size of modulation constellation and the actual emission requirements. The simulation results show that with the same BER（Bit Error Rate）of 10^-4 the required SNR （Signal-to
-Noise Ratio) in proposed algorithm is higher than IWFP algorithm nearly 3 dB. The proposed algorithm is lower than that in the traditional distribution algorithm by nearly 8 dB. The proposed algorithm is close to the optimal performance of the system with the low complexity of computing.

Key words: adaptive orthogonal frequency division multiplexing (OFDM), iterative water-filling power(IWFP)algorithm, bit and power allocation