4月12日下午，国立雷恩应用科学学院Jean-François Hélard教授在信息学院四楼报告厅作了题为“多载波技术的原理与其在广播和蜂窝系统的应用”的学术报告。信息学院杨明强副教授主持报告，通信与信息系统专业的部分老师和学生在现场聆听了报告。

    报告中，Jean-François Hélard教授首先指出当前通信领域的4G技术（LTE长期演进计划)、大部分的广播数字电视和无线标准的空中接口都是建立在多载波调制的基础上，其中正交频分复用（OFDM）就是一种多载波调制。他给大家解释了多载波技术的主要工作原理和它在频率与时间选择性无线移动信道中性能优异的原因，通过对传输信号的底层技术、频带保护间隔、融合信道编码和差分信号相干解调的研究，他找到了频率和时间选择性衰落信道系统参数的选择方法，同时也解决了峰值功率和实际实施的问题。最后，他为大家简单介绍了多载波调制技术在DVB-T/DVB-T2/DVB-NGH、DMB-T以及蜂窝网络LTE/LTE-A中的应用。

    Jean-François Hélard教授的精彩报告赢得了现场观众热烈的掌声，也使在场师生们对国际上多载波调制技术的发展和应用有了进一步的认识和了解。

报告人简介：Professor Jean-François Hélard received his Dipl.-Ing. and his Ph.D in electronics and signal processing from the National Institute of Applied Sciences (INSA) in Rennes, France, in 1981 and 1992, respectively. From 1982 to 1997, he was research engineer and then head of channel coding for the digital broadcasting research group at France Telecom Research Center in Rennes. In 1997, he joined INSA, where he is currently Professor and Director of Research INSA Rennes. He is also Deputy Director of the Joint Research Unit UMR IETR (Institute of Electronics and Telecommunications in Rennes), created in 2002 in association with the CNRS and University of Rennes 1. His research interests lie in signal processing techniques for digital communications, such as space-time and channel coding, multi-carrier modulation, multi-user communications, resource allocation, spectrum and energy efficient techniques... He is involved in several European and national research projects in the fields of digital video terrestrial broadcasting, mobile radio communications and cellular networks, power-line and ultra-wide-band communications, cooperative communications and relaying techniques. Prof. J-F. Hélard is a senior member of IEEE, author and co-author of more than 200 technical papers in international scientific journals and conferences, and holds 14 European patents.