Public defence in Communications Engineering and Networking Technology, M.Sc. Xiyu Wang

The title of the thesis: Multi-Antenna Ambient Backscatter Communications: Performance Optimization and Analysis

Doctoral student: Xiyu Wang
Opponent: Prof. Aggelos Bletsas, Technical University of Crete, Greece
Custos: Prof. Riku Jäntti, Aalto University School of Electrical Engineering, Department of Information and Communications Engineering

IoT networks foresee an ever-increasing number of connecting devices. The large-scale connectivity is restricted by the available energy and spectrum. The emerging ambient backscatter communications (AmBC) is a sustainable solution that allows data transmission with ultra-low power consumption and improved spectrum efficiency. However, a wide deployment of AmBC is limited by the system performance, the achievable communication range and the data rate, which are caused by poor receiver performance. Therefore, to popularize AmBC, the thesis studies the question of how to improve the demodulation performance of AmBC receivers. 

In this thesis, we explore the utilization of multiple antennas on the system components, allowing the solutions to operate without assuming specific signal types or requiring more information on the ambient system. The thesis investigates the designs of multi-antenna receiver and multi-antenna backscatter device, and contains both theoretical derivation and practical demonstration of the resultant designs. 

The proposed designs are optimal as they are derived by minimizing the demodulation error probability. The resultant receivers generalize to different AmBC deployments regardless of the signal types. The analyses suggest the placement of a backscatter device for achieving a better demodulation performance, and a multi-antenna backscatter device should be used when there are multiple ambient sources. Moreover, receiver implementation details are discussed in terms of analog-to-digital converter’s dynamic range and wideband system deployment. Thus, the proposed designs enhance AmBC system performance, which opens many more IoT use case possibilities.

Thesis available for public display 10 days prior to the defence at: https://aaltodoc.aalto.fi/doc_public/eonly/riiputus/

Contact information:

Doctoral theses in the School of Electrical Engineering: https://aaltodoc.aalto.fi/handle/123456789/53