V. Tejovathi and S.Swarnalatha 2025. A Novel Power-Optimized Optical Modem for Reliable, Long-Distance Communication Using MIMO-GFDM in Underwater Communication and Beyond 5G Wireless Systems. International Journal of Computational and Experimental Science and Engineering. 11, 2 (May 2025). DOI:https://doi.org/10.22399/ijcesen.1820.