DR. K. RAVI KUMAR, V. S. K. Optimum Hierarchical Modulations for OFDM Systems and Uplink Virtual MIMO Systems. International Journal of Emerging Trends in Science and Technology, [S. l.], v. 2, n. 02, 2015. Disponível em: http://igmpublication.com/ijetst.in/index.php/ijetst/article/view/515. Acesso em: 2 mar. 2025.