November 27, 2023

Fraunhofer HHI researcher Sreelal Maravanchery Mana completes dissertation with “magna cum laude”

November 27, 2023

Sreelal Maravanchery Mana, research associate in the Photonic Networks and Systems department (PN) at Fraunhofer Heinrich-Hertz-Institut (HHI), completed his dissertation entitled “MIMO Channel Modelling, Measurements, and Performance Evaluation for Optical Wireless Communication in Indoor Scenarios” at the Technical University of Berlin  with the final mark “magna cum laude”.

In his doctoral thesis, Sreelal characterized optical wireless communication (OWC) channels in various indoor scenarios. He developed a new methodology for modelling OWC channels, combining an accurate 3D environment model with a computationally more efficient approach to simulating the propagation of light in the environment, including diffuse reflections.

He divided his thesis into three parts: The first part introduces the reader to OWC channels through measurements in realistic indoor scenarios. In the second part, he describes the new channel modelling method in detail. The LIDAR technology scans the indoor 3D environment and determines the reflectance values of objects and walls in the scenario. This allows him to replace the classical raytracing method by modelling the line-of-sight and first reflections in the frequency domain, and all residual reflections by means of an integrating sphere model. In the third part of the dissertation, Sreelal validates the new modelling approach by experiments in realistic scenarios. This comparison shows that simulations agree very well with experimental results. The new model allows faster simulation of the channel between multiple transmitters and multiple receivers in mobile scenarios, which had been major shortcomings of the previously applied approach.

Hailing from the Malappuram district in the southern state of Kerala in India, Sreelal Maravanchery Mana holds a Bachelor of Technology degree in Electronics and Communication Engineering from CUSAT, Kerala, India (2014), and a Master of Technology degree in Optical Engineering from IIST, Thiruvananthapuram, India (2017). After completing his Master's degree, his goal was to pursue a research career in an international environment, which motivated him to join Fraunhofer HHI in Berlin. Passionate about his research, he served as a Marie Curie Research Fellow in the VisIoN project in the PN department from August 2018 to February 2022, focusing on OWC channel modeling and measurements. Since March 2022, Sreelal has taken on the roles of research assistant at TU Berlin as well as research associate at Fraunhofer HHI in the 6G-RIC project. There he contributes to the software solution for network deployment planning of indoor wireless systems. Apart from his academic pursuits, Sreelal is a gifted singer, performing in various Indian music concerts. Additionally, he is interested in cooking and loves to travel.

The examination board chaired by Prof. Dr.-Ing. Friedel Gerfers (TU Berlin) consisted of Prof. Dr.-Ing. Ronald Freund (TU Berlin, Fraunhofer HHI), Prof. Dr. rer. nat. habil. Volker Jungnickel (TU Berlin, Fraunhofer HHI), and Prof. Dr. Rafael Perez Jimenez (University of Las Palmas de Gran Canaria, Spain).