Dissertation Defense

Electromagnetic Concepts to Enhance Communication in Harsh RF Environments

Mohammad Amjadi


Planning the future wireless networks such as the fifth generation and beyond to be deployed in congested and complex electromagnetic environments requires efficient techniques for co-channel external and internal (self-) interference cancelation. Benefited from electromagnetic concepts, signal processing techniques, or combination of both, the first part of this work reports on electromagnetic solutions for 1) the mitigation of self-interference issue in wireless transceivers for enabling full-duplex communication and 2) the cancelation of external interference caused by the other users, multipath effects, or jammers. Compact ultra-wideband antenna systems are devised that feature an unprecedented level of self-interference cancellation yet provide consistent radiation characteristics. To manage external interference, first, a concept which will be referred to as Array Signal Segregation using an Iterative Approach (ASSIA) is presented to spatially segregate signals in Rayleigh fading environments. In conjunction with ASSIA, a super-resolution signal detection algorithm based on a novel Closely spaced Nulls Synthesis Method (CNSM) is then developed which, for the first time, demonstrates capability of an antenna array in resolving direction of arrival of closely spaced correlated signals in the absence of a priori knowledge of the number of the incident signals.

The second part of this work reports on a robust, cost-effective, high data-rate subsurface communication technique for enabling long-distance communication in drilling process. The concept of using the drilling tools as a Single Conductor Transmission Line (SCTL) is introduced and a compact SCTL transducer is designed at low HF band to support the required data-rate for real time monitoring and controlling.

Sponsored by

Professor Kamal Sarabandi