An efficient bit loading algorithm for OFDM system.

We propose an efficient bit-loading algorithm to minimize the total power to transmit a target rate of a single user in OFDM communication systems. Considering the digital modulations exploited by 802. 11a, which are BPSK, QPSK, 16QAM and 64QAM (constellation using Gray code and each sub-carrier carrying a maximum of 6 bits) , ⌊ R_T/6 ⌋ subcarriers which have litter power addition are allocated with 2 bits each time. The proposed bit loading algorithm is optimal and has the same performance as Hughes-Hartogs algorithm, but greatly reduces the computational complexity. Simulation results show that the proposed bit loading algorithm has the same bit allocation results as Hughes-Hartogs algorithm, but the computational complexity is less than 50% compared with that of Hughes-Hartogs algorithm. The computational complexity will be further reduced when the transmission rate or subcarriers number increases. [ABSTRACT FROM AUTHOR]