Orthogonal Frequency Division Multiplexing is a multicarrier modulation technique which segregates the accessible spectrum into subcarrier, among every subcarrier attaining a low rate data stream. A large number of research work has been developed till now to enhance the performance of the system. Specifically the downstream transmission is considered as the prominent topic among the researchers. For this, in traditional work, an OFDM-PON communication system using m-QAM mapped mechanism was developed but found to be less efficient with the perspective of data rate, subcarriers and channel capacity. Thus, in this study a novel approach has been proposed to overcome the issues of traditional work. For achieving the best results, the concept of dispersion compensation is introduced by the author. Along with this, the analysis of the proposed work over highest data rate is also done.