The OFDM (orthogonal frequency division multiplexing) transmission technique has a flexibility to adapt the modulation scheme on sub-carriers according to the channel performance, i.e. signal-to-noise ratio (SNR). In an outdoor high mobility environment most of the adaptive OFDM systems provide channel information, transmitted from the receiver. The allocation of bits to sub-carriers is performed by so-called loading algorithms based on information provided by the receiver. Presently, modification of loading algorithm is reported with observed decrease in computational complexity without any loss of performance as compared to the known algorithm. The study was carried out for mobile communication systems considering the channel to be frequency selective and fast fading.