On May 30th, 2020, Le Quy Don Technical University (LQDTU) has organized the Academy-level doctoral thesis defense in English for PhD student Le Thi Thanh Huyen, Electronic Engineering major, titled: “Repeated Index Modulation for OFDM Systems”. After more than 40 years of the postgraduate training, LQDTU has possessed 450 PhD students who have successfully defended their PhD thesis, and Le Thi Thanh Huyen is the 450th PhD student.
Her supervisor is Prof. Dr. Tran Xuan Nam (LQDTU). The Doctoral Committee includes: Assoc. Prof. Dr. Nguyen Quoc Binh (LQDTU) – Chair of the Committee; Assoc. Prof. Dr. Le Nhat Thang (Posts and Telecommunications Institute of Technology) – Reviewer 1; Assoc. Prof. Tran Duc Tan (Phenikaa University) – Reviewer 2; Assoc. Prof. Dr. Nguyen Xuan Quyen (Hanoi University of Science and Technology) – Reviewer 3; Assoc. Prof. Pham Thanh Hiep (LQDTU) – Secretary; Dr. Nguyen The Quang (LQDTU) – Member; and Dr. Nguyen Dang Thanh (Vietnam Television) – Member.
After three hours of working hard and dealing with a variety of comments, questions, responses and discussions, the Committee agreed to make an assessment that Mrs. Le Thi Thanh Huyen has successfully defended her PhD thesis and the major contributions of the thesis are summarized as follows: The thesis is an in-depth study of index modulation for OFDM systems. There is a close correspondence between the thesis content and thesis title. The thesis has successfully completed the objectives and tasks, reflected in the contents of published works as well as the thesis content. Two main research results are:
– Proposing an enhanced IM-OFDM system with spatial diversity using the maximal ratio combination and selection combination (abv. as RIM-OFDM-MRC and RIM-OFDM-SC, respectively). The closed-form expressions for the index error probability (IEP) and symbol error probability (SEP) of RIM-OFDM-MRC and RIM-OFDM-SC under both perfect and imperfect channel state information (CSI) conditions are derived to analyze the error performance. Simulation results are also provided to validate the theoretical analysis. This contribution can be applied to wireless single input multiple output systems such as the uplink in the LTE system, where the mobile handset has only a single antenna.
– Proposing and analyzing the performance of an enhanced scheme of IM-OFDM, referred to as repeated IM-OFDM with coordinate interleaving (RIM-OFDM-CI). Three low-complexity detectors for RIM-OFDM-CI, which can significantly reduce the computational complexity while still achieving nearly similar system error performance of the optimal detector, are proposed. This contribution is scientifically significant, which can be applied to the communication systems requiring the low-complexity, the reliability but not high data rate such as IoT, D2D, Machine Type communications and others.
PhD student Le Thi Thanh Huyen has already published 05 publications in high quality journal, in which her first paper has been published in the prestigious international journal (ISI-Q2). Also two papers of hers have been published in the journal list approved by the State Council for Professor Title of Vietnam (01 in Military Technical Academy Journal of Science and Technique and 01 in the Journal of Research and Development on Information and Communication Technology (RD-ICT) of Journal of Information and Communication Technology) and 02 conference papers indexed by Scopus (ATC 2017 and NICS 2018). Otherwise, she also possesses 01 paper which is under review of another prestigious international journal (ISI-Q1). All the publications are directly related to thesis contents and PhD student Le Thi Thanh Huyen is the first author. With the above publications, the thesis of PhD student Le This Thanh Huyen meets the requirements of the international postgraduate training standards of many high-rank universities in the world.