The optimal subchannel and bit allocation problem for OFDM

Abstract

The advantages of the orthogonal frequency division multiplexing (OFDM) are high spectral efficiency, resiliency to RF interference, and lower multi-path distortion. To further utilize vast channel capacity of the multiuser OFDM, one has to find the efficient adaptive subchannel and bit allocation among users. In this paper, we propose an 0-1 integer programming model formulating the optimal subchannel and bit allocation problem of the multiuser OFDM. We provide an efficient Lagrangian dual formulation with fast solution approach. Simulation results are provided to show the effectiveness of the 0-1 integer programming model. MATLAB simulation on a system employing Mary quardarature amplitude modulation (MQAM) assuming a frequency-selective channel consisting of five independent Rayleigh multipaths are carried with the optimal subchannel and bit allocation solution generated by 0-1 integer programming model.